Compressor with liquid injection cooling

Information

  • Patent Grant
  • 9856878
  • Patent Number
    9,856,878
  • Date Filed
    Wednesday, January 13, 2016
    8 years ago
  • Date Issued
    Tuesday, January 2, 2018
    6 years ago
Abstract
A positive displacement rotary compressor is designed for near isothermal compression, high pressure ratios, high revolutions per minute, high efficiency, mixed gas/liquid compression, a low temperature increase, a low outlet temperature, and/or a high outlet pressure. Liquid injectors provide cooling liquid that cools the working fluid and improves the efficiency of the compressor. A gate moves within the compression chamber to either make contact with or be proximate to the rotor as it turns.
Description
BACKGROUND

1. Technical Field


The invention generally relates to fluid pumps, such as compressors and expanders. More specifically, preferred embodiments utilize a novel rotary compressor design for compressing air, vapor, or gas for high pressure conditions over 200 psi and power ratings above 10 HP.


2. Related Art


Compressors have typically been used for a variety of applications, such as air compression, vapor compression for refrigeration, and compression of industrial gases. Compressors can be split into two main groups, positive displacement and dynamic. Positive displacement compressors reduce the compression volume in the compression chamber to increase the pressure of the fluid in the chamber. This is done by applying force to a drive shaft that is driving the compression process. Dynamic compressors work by transferring energy from a moving set of blades to the working fluid.


Positive displacement compressors can take a variety of forms. They are typically classified as reciprocating or rotary compressors. Reciprocating compressors are commonly used in industrial applications where higher pressure ratios are necessary. They can easily be combined into multistage machines, although single stage reciprocating compressors are not typically used at pressures above 80 psig. Reciprocating compressors use a piston to compress the vapor, air, or gas, and have a large number of components to help translate the rotation of the drive shaft into the reciprocating motion used for compression. This can lead to increased cost and reduced reliability. Reciprocating compressors also suffer from high levels of vibration and noise. This technology has been used for many industrial applications such as natural gas compression.


Rotary compressors use a rotating component to perform compression. As noted in the art, rotary compressors typically have the following features in common: (1) they impart energy to the gas being compressed by way of an input shaft moving a single or multiple rotating elements; (2) they perform the compression in an intermittent mode; and (3) they do not use inlet or discharge valves. (Brown, Compressors: Selection and Sizing, 3rd Ed., at 6). As further noted in Brown, rotary compressor designs are generally suitable for designs in which less than 20:1 pressure ratios and 1000 CFM flow rates are desired. For pressure ratios above 20:1, Royce suggests that multistage reciprocating compressors should be used instead.


Typical rotary compressor designs include the rolling piston, screw compressor, scroll compressor, lobe, liquid ring, and rotary vane compressors. Each of these traditional compressors has deficiencies for producing high pressure, near isothermal conditions.


The design of a rotating element/rotor/lobe against a radially moving element/piston to progressively reduce the volume of a fluid has been utilized as early as the mid-19th century with the introduction of the “Yule Rotary Steam Engine.” Developments have been made to small-sized compressors utilizing this methodology into refrigeration compression applications. However, current Yule-type designs are limited due to problems with mechanical spring durability (returning the piston element) as well as chatter (insufficient acceleration of the piston in order to maintain contact with the rotor).


For commercial applications, such as compressors for refrigerators, small rolling piston or rotary vane designs are typically used. (P N Ananthanarayanan, Basic Refrigeration and Air Conditioning, 3rd Ed., at 171-72.) In these designs, a closed oil-lubricating system is typically used.


Rolling piston designs typically allow for a significant amount of leakage between an eccentrically mounted circular rotor, the interior wall of the casing, and/or the vane that contacts the rotor. By spinning the rolling piston faster, the leakages are deemed acceptable because the desired pressure and flow rate for the application can be easily reached even with these losses. The benefit of a small self-contained compressor is more important than seeking higher pressure ratios.


Rotary vane designs typically use a single circular rotor mounted eccentrically in a cylinder slightly larger than the rotor. Multiple vanes are positioned in slots in the rotor and are kept in contact with the cylinder as the rotor turns typically by spring or centrifugal force inside the rotor. The design and operation of these type of compressors may be found in Mark's Standard Handbook for Mechanical Engineers, Eleventh Edition, at 14:33-34.


In a sliding-vane compressor design, vanes are mounted inside the rotor to slide against the casing wall. Alternatively, rolling piston designs utilize a vane mounted within the cylinder that slides against the rotor. These designs are limited by the amount of restoring force that can be provided and thus the pressure that can be yielded.


Each of these types of prior art compressors has limits on the maximum pressure differential that it can provide. Typical factors include mechanical stresses and temperature rise. One proposed solution is to use multistaging. In multistaging, multiple compression stages are applied sequentially. Intercooling, or cooling between stages, is used to cool the working fluid down to an acceptable level to be input into the next stage of compression. This is typically done by passing the working fluid through a heat exchanger in thermal communication with a cooler fluid. However, intercooling can result in some condensation of liquid and typically requires filtering out of the liquid elements. Multistaging greatly increases the complexity of the overall compression system and adds costs due to the increased number of components required. Additionally, the increased number of components leads to decreased reliability and the overall size and weight of the system are markedly increased.


For industrial applications, single- and double-acting reciprocating compressors and helical-screw type rotary compressors are most commonly used. Single-acting reciprocating compressors are similar to an automotive type piston with compression occurring on the top side of the piston during each revolution of the crankshaft. These machines can operate with a single-stage discharging between 25 and 125 psig or in two stages, with outputs ranging from 125 to 175 psig or higher. Single-acting reciprocating compressors are rarely seen in sizes above 25 HP. These types of compressors are typically affected by vibration and mechanical stress and require frequent maintenance. They also suffer from low efficiency due to insufficient cooling.


Double-acting reciprocating compressors use both sides of the piston for compression, effectively doubling the machine's capacity for a given cylinder size. They can operate as a single-stage or with multiple stages and are typically sized greater than 10 HP with discharge pressures above 50 psig. Machines of this type with only one or two cylinders require large foundations due to the unbalanced reciprocating forces. Double-acting reciprocating compressors tend to be quite robust and reliable, but are not sufficiently efficient, require frequent valve maintenance, and have extremely high capital costs.


Lubricant-flooded rotary screw compressors operate by forcing fluid between two intermeshing rotors within a housing which has an inlet port at one end and a discharge port at the other. Lubricant is injected into the chamber to lubricate the rotors and bearings, take away the heat of compression, and help to seal the clearances between the two rotors and between the rotors and housing. This style of compressor is reliable with few moving parts. However, it becomes quite inefficient at higher discharge pressures (above approximately 200 psig) due to the intermeshing rotor geometry being forced apart and leakage occurring. In addition, lack of valves and a built-in pressure ratio leads to frequent over or under compression, which translates into significant energy efficiency losses.


Rotary screw compressors are also available without lubricant in the compression chamber, although these types of machines are quite inefficient due to the lack of lubricant helping to seal between the rotors. They are a requirement in some process industries such as food and beverage, semiconductor, and pharmaceuticals, which cannot tolerate any oil in the compressed air used in their processes. Efficiency of dry rotary screw compressors are 15-20% below comparable injected lubricated rotary screw compressors and are typically used for discharge pressures below 150 psig.


Using cooling in a compressor is understood to improve upon the efficiency of the compression process by extracting heat, allowing most of the energy to be transmitted to the gas and compressing with minimal temperature increase. Liquid injection has previously been utilized in other compression applications for cooling purposes. Further, it has been suggested that smaller droplet sizes of the injected liquid may provide additional benefits.


In U.S. Pat. No. 4,497,185, lubricating oil was intercooled and injected through an atomizing nozzle into the inlet of a rotary screw compressor. In a similar fashion, U.S. Pat. No. 3,795,117 uses refrigerant, though not in an atomized fashion, that is injected early in the compression stages of a rotary screw compressor. Rotary vane compressors have also attempted finely atomized liquid injection, as seen in U.S. Pat. No. 3,820,923.


In each example, cooling of the fluid being compressed was desired. Liquid injection in rotary screw compressors is typically done at the inlet and not within the compression chamber. This provides some cooling benefits, but the liquid is given the entire compression cycle to coalesce and reduce its effective heat transfer coefficient. Additionally, these examples use liquids that have lubrication and sealing as a primary benefit. This affects the choice of liquid used and may adversely affect its heat transfer and absorption characteristics. Further, these styles of compressors have limited pressure capabilities and thus are limited in their potential market applications.


Rotary designs for engines are also known, but suffer from deficiencies that would make them unsuitable for an efficient compressor design. The most well-known example of a rotary engine is the Wankel engine. While this engine has been shown to have benefits over conventional engines and has been commercialized with some success, it still suffers from multiple problems, including low reliability and high levels of hydrocarbon emissions.


Published International Pat. App. No. WO 2010/017199 and U.S. Pat. Pub. No. 2011/0023814 relate to a rotary engine design using a rotor, multiple gates to create the chambers necessary for a combustion cycle, and an external cam-drive for the gates. The force from the combustion cycle drives the rotor, which imparts force to an external element. Engines are designed for a temperature increase in the chamber and high temperatures associated with the combustion that occurs within an engine. Increased sealing requirements necessary for an effective compressor design are unnecessary and difficult to achieve. Combustion forces the use of positively contacting seals to achieve near perfect sealing, while leaving wide tolerances for metal expansion, taken up by the seals, in an engine. Further, injection of liquids for cooling would be counterproductive and coalescence is not addressed.


Liquid mist injection has been used in compressors, but with limited effectiveness. In U.S. Pat. No. 5,024,588, a liquid injection mist is described, but improved heat transfer is not addressed. In U.S. Pat. Publication. No. U.S. 2011/0023977, liquid is pumped through atomizing nozzles into a reciprocating piston compressor's compression chamber prior to the start of compression. It is specified that liquid will only be injected through atomizing nozzles in low pressure applications. Liquid present in a reciprocating piston compressor's cylinder causes a high risk for catastrophic failure due to hydrolock, a consequence of the incompressibility of liquids when they build up in clearance volumes in a reciprocating piston, or other positive displacement, compressor. To prevent hydrolock situations, reciprocating piston compressors using liquid injection will typically have to operate at very slow speeds, adversely affecting the performance of the compressor.


The prior art lacks compressor designs in which the application of liquid injection for cooling provides desired results for a near-isothermal application. This is in large part due to the lack of a suitable positive displacement compressor design that can both accommodate a significant amount of liquid in the compression chamber and pass that liquid through the compressor outlet without damage.


BRIEF SUMMARY

The presently preferred embodiments are directed to rotary compressor designs. These designs are particularly suited for high pressure applications, typically above 200 psig with pressure ratios typically above that for existing high-pressure positive displacement compressors.


One or more embodiments provide a method of operating a compressor having a casing defining a compression chamber, and a rotatable drive shaft configured to drive the compressor. The method includes compressing a working fluid using the compressor such that a speed of the drive shaft relative to the casing is at least 450 rpm, and a pressure ratio of the compressor is at least 15:1. The method also includes injecting liquid coolant into the compression chamber during the compressing.


According to one or more of these embodiments, the compressor is a positive displacement rotary compressor that includes a rotor connected to the drive shaft for rotation with the drive shaft relative to the casing.


According to one or more of these embodiments, the compressing includes moving the working fluid into the compression chamber through an inlet port in the compression chamber. The compressing also includes expelling compressed working fluid out of the compression chamber through an outlet port in the compression chamber. The pressure ratio is a ratio of (a) an absolute inlet pressure of the working fluid at the inlet port, to (b) an absolute outlet pressure of the working fluid expelled from the compression chamber through the outlet port.


According to one or more of these embodiments, the speed is between 450 and 1800 rpm and/or greater than 500, 600, 700, and/or 800 rpm.


According to one or more of these embodiments, the pressure ratio is between 15:1 and 100:1, at least 20:1, at least 30:1, and/or at least 40:1.


According to one or more of these embodiments, the working fluid is a multi-phase fluid that has a liquid volume fraction at an inlet into the compression chamber of at least 1, 2, 3, 4, 5, 10, 20, 30 and/or 40%.


According to one or more of these embodiments, the compressed fluid is expelled from the compressor at an outlet pressure of between 200 and 6000 psig and/or at least 200, 225, 250, 275, 300, 325, 350, 400, 450, 500, 750, 1000, 1250, 1500, 2000, 3000, 4000, and/or 5000 psig.


According to one or more of these embodiments, an outlet temperature of the compressed working fluid being expelled through the outlet port is less than 100, 150, 200, 250, and/or 300 degrees C. The outlet temperature may be greater than 0 degrees C.


According to one or more of these embodiments, an outlet temperature of the compressed working fluid being expelled through the outlet port exceeds an inlet temperature of the working fluid entering the compression chamber through the inlet port by less than 100, 150, 200, 250, and/or 300 degrees C.


According to one or more of these embodiments, a rotational axis of the rotor is oriented in a horizontal direction during the compressing.


According to one or more of these embodiments, the injecting includes injecting atomized liquid coolant with an average droplet size of 300 microns or less into a compression volume defined between the rotor and an inner wall of the compression chamber.


According to one or more of these embodiments, the injecting includes injecting liquid coolant into the compression chamber in a direction that is perpendicular to or at least partially counter to a flow direction of the working fluid adjacent to the location of liquid coolant injection.


According to one or more of these embodiments, the injecting includes discontinuously injecting liquid coolant into the compression chamber over the course of each compression cycle. During each compression cycle, coolant injection begins at or after the first 20% of the compression cycle.


According to one or more of these embodiments, the injecting includes injecting the liquid coolant into the compression chamber at an average rate of at least 3, 4, 5, 6, and/or 7 gallons per minute (gpm), and/or between 3 and 20 gpm.


According to one or more of these embodiments, the injecting includes injecting liquid coolant into a compression volume defined between the rotor and an inner wall of the compression chamber during the compressor's highest rate of compression over the course of a compression cycle of the compressor.


According to one or more of these embodiments, the compression chamber is defined by a cylindrical inner wall of the casing; the compression chamber includes an inlet port and an outlet port; the rotor has a sealing portion that corresponds to a curvature of the inner wall of the casing and has a constant radius, and a non-sealing portion having a variable radius; the rotor rotates concentrically relative to the cylindrical inner wall during the compressing; the compressor includes at least one liquid injector connected with the casing; the at least one liquid injector carries out the injecting; the compressor includes a gate having a first end and a second end, and operable to move within the casing to locate the first end proximate to the rotor as the rotor rotates during the compressing; the gate separates an inlet volume and a compression volume in the compression chamber; the inlet port is configured to enable suction in of the working fluid; and the outlet port is configured to enable expulsion of both liquid and gas.


One or more embodiments of the invention provide a compressor that is configured to carry out one or more of these methods.


One or more embodiments provide a compressor comprising: a casing with an inner wall defining a compression chamber; a positive displacement compressing structure movable relative to the casing to compress a working fluid in the compression chamber; a rotatable drive shaft configured to drive the compressing structure; and at least one liquid injector connected to the casing and configured to inject liquid coolant into the compression chamber during compression of the working fluid.


According to one or more of these embodiments, the compressor is configured and shaped to compress the working fluid at a drive shaft speed of at least 450 rpm with a pressure ratio of at least 15:1.


According to one or more of these embodiments, the compressor is a positive displacement rotary compressor, and the compressing structure is a rotor connected to the drive shaft for rotation with the drive shaft relative to the casing.


According to one or more of these embodiments, the compression chamber includes an inlet port and an outlet port; the compressor is shaped and configured to receive the working fluid into the compression chamber via the inlet port and expel the working fluid out of the compression chamber via the outlet port; and the pressure ratio is a ratio of (a) an absolute inlet pressure of the working fluid at the inlet port, to (b) an absolute outlet pressure of the working fluid expelled from the compression chamber through the outlet port.


According to one or more of these embodiments, the compression chamber includes an inlet port and an outlet port; the inner wall is cylindrical; the rotor has a sealing portion that corresponds to a curvature of the inner wall and has a constant radius, and a non-sealing portion having a variable radius; the rotor is connected to the casing for concentric rotation within the compression chamber; the compressor includes a gate having a first end and a second end, and operable to move within the casing to locate the first end proximate to the rotor as the rotor rotates; the gate separates an inlet volume and a compression volume in the compression chamber; the inlet port is configured to enable suction in of the working fluid; and the outlet is configured to enable expulsion of both liquid and gas.


One or more embodiments provides a positive displacement compressor, comprising: a cylindrical rotor casing, the rotor casing having an inlet port, an outlet port, and an inner wall defining a rotor casing volume; a rotor, the rotor having a sealing portion that corresponds to a curvature of the inner wall of the rotor casing; at least one liquid injector connected with the rotor casing to inject liquids into the rotor casing volume; and a gate having a first end and a second end, and operable to move within the rotor casing to locate the first end proximate to the rotor as it turns. The gate may separate an inlet volume and a compression volume in the rotor casing volume. The inlet port may be configured to enable suction in of gas. The outlet port may be configured to enable expulsion of both liquid and gas.


According to one or more of these embodiments, the at least one liquid injector is positioned to inject liquid into an area within the rotor casing volume where compression occurs during operation of the compressor.


One or more embodiments provides a method for compressing a fluid, the method comprising: providing a rotary compressor, the rotary compressor having a rotor, rotor casing, intake volume, a compression volume, and outlet valve; receiving air into the intake volume; rotating the rotor to increase the intake volume and decrease the compression volume; injecting cooling liquid into the chamber; rotating the rotor to further increase and decrease the compression volume; opening the outlet valve to release compressed gas and liquid; and separating the liquid from the compressed gas.


According to one or more of these embodiments, injected cooling liquid is atomized when injected, absorbs heat, and is directed toward the outlet valve.


One or more embodiments provides a positive displacement compressor, comprising: a compression chamber, including a cylindrical-shaped casing having a first end and a second end, the first and second end aligned horizontally; a shaft located axially in the compression chamber; a rotor concentrically mounted to the shaft; liquid injectors located to inject liquid into the compression chamber; and a dual purpose outlet operable to release gas and liquid.


According to one or more of these embodiments, the rotor includes a curved portion that forms a seal with the cylindrical-shaped casing, and balancing holes.


One illustrative embodiment of the design includes a non-circular-shaped rotor rotating within a cylindrical casing and mounted concentrically on a drive shaft inserted axially through the cylinder. The rotor is symmetrical along the axis traveling from the drive shaft to the casing with cycloid and constant radius portions. The constant radius portion corresponds to the curvature of the cylindrical casing, thus providing a sealing portion. The changing rate of curvature on the other portions provides for a non-sealing portion. In this illustrative embodiment, the rotor is balanced by way of holes and counterweights.


A gate structured similar to a reciprocating rectangular piston is inserted into and withdrawn from the bottom of the cylinder in a timed manner such that the tip of the piston remains in contact with or sufficiently proximate to the surface of the rotor as it turns. The coordinated movement of the gate and the rotor separates the compression chamber into a low pressure and high pressure region.


As the rotor rotates inside the cylinder, the compression volume is progressively reduced and compression of the fluid occurs. At the same time, the intake side is filled with gas through the inlet. An inlet and exhaust are located to allow fluid to enter and exit the chamber at appropriate times. During the compression process, atomized liquid is injected into the compression chamber in such a way that a high and rapid rate of heat transfer is achieved between the gas being compressed and the injected cooling liquid. This results in near isothermal compression, which enables a much higher efficiency compression process.


The rotary compressor embodiments sufficient to achieve near isothermal compression are capable of achieving high pressure compression at higher efficiencies. It is capable of compressing gas only, a mixture of gas and liquids, or for pumping liquids. As one of ordinary skill in the art would appreciate, the design can also be used as an expander.


The particular rotor and gate designs may also be modified depending on application parameters. For example, different cycloidal and constant radii may be employed. Alternatively, double harmonic, polynomial, or other functions may be used for the variable radius. The gate may be of one or multiple pieces. It may implement a contacting tip-seal, liquid channel, or provide a non-contacting seal by which the gate is proximate to the rotor as it turns.


Several embodiments provide mechanisms for driving the gate external to the main casing. In one embodiment, a spring-backed cam drive system is used. In others, a belt-based system with or without springs may be used. In yet another, a dual cam follower gate positioning system is used. Further, an offset gate guide system may be used. Further still, linear actuator, magnetic drive, and scotch yoke systems may be used.


The presently preferred embodiments provide advantages not found in the prior art. The design is tolerant of liquid in the system, both coming through the inlet and injected for cooling purposes. High pressure ratios are achievable due to effective cooling techniques. Lower vibration levels and noise are generated. Valves are used to minimize inefficiencies resulting from over- and under-compression common in existing rotary compressors. Seals are used to allow higher pressures and slower speeds than typical with other rotary compressors. The rotor design allows for balanced, concentric motion, reduced acceleration of the gate, and effective sealing between high pressure and low pressure regions of the compression chamber.


These and other aspects of various embodiments of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. In one embodiment of the invention, the structural components illustrated herein are drawn to scale. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. In addition, it should be appreciated that structural features shown or described in any one embodiment herein can be used in other embodiments as well. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.


All closed-ended (e.g., between A and B) and open-ended (greater than C) ranges of values disclosed herein explicitly include all ranges that fall within or nest within such ranges. For example, a disclosed range of 1-10 is understood as also disclosing, among other ranged, 2-10, 1-9, 3-9, etc.





BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.



FIG. 1 is a perspective view of a rotary compressor with a spring-backed cam drive in accordance with an embodiment of the present invention.



FIG. 2 is a right-side view of a rotary compressor with a spring-backed cam drive in accordance with an embodiment of the present invention.



FIG. 3 is a left-side view of a rotary compressor with a spring-backed cam drive in accordance with an embodiment of the present invention.



FIG. 4 is a front view of a rotary compressor with a spring-backed cam drive in accordance with an embodiment of the present invention.



FIG. 5 is a back view of a rotary compressor with a spring-backed cam drive in accordance with an embodiment of the present invention.



FIG. 6 is a top view of a rotary compressor with a spring-backed cam drive in accordance with an embodiment of the present invention.



FIG. 7 is a bottom view of a rotary compressor with a spring-backed cam drive in accordance with an embodiment of the present invention.



FIG. 8 is a cross-sectional view of a rotary compressor with a spring-backed cam drive in accordance with an embodiment of the present invention.



FIG. 9 is a perspective view of rotary compressor with a belt-driven, spring-biased gate positioning system in accordance with an embodiment of the present invention.



FIG. 10 is a perspective view of a rotary compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.



FIG. 11 is a right-side view of a rotary compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.



FIG. 12 is a left-side view of a rotary compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.



FIG. 13 is a front view of a rotary compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.



FIG. 14 is a back view of a rotary compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.



FIG. 15 is a top view of a rotary compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.



FIG. 16 is a bottom view of a rotary compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.



FIG. 17 is a cross-sectional view of a rotary compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.



FIG. 18 is perspective view of a rotary compressor with a belt-driven gate positioning system in accordance with an embodiment of the present invention.



FIG. 19 is perspective view of a rotary compressor with an offset gate guide positioning system in accordance with an embodiment of the present invention.



FIG. 20 is a right-side view of a rotary compressor with an offset gate guide positioning system in accordance with an embodiment of the present invention.



FIG. 21 is a front view of a rotary compressor with an offset gate guide positioning system in accordance with an embodiment of the present invention.



FIG. 22 is a cross-sectional view of a rotary compressor with an offset gate guide positioning system in accordance with an embodiment of the present invention.



FIG. 23 is perspective view of a rotary compressor with a linear actuator gate positioning system in accordance with an embodiment of the present invention.



FIGS. 24A and B are right side and cross-section views, respectively, of a rotary compressor with a magnetic drive gate positioning system in accordance with an embodiment of the present invention



FIG. 25 is perspective view of a rotary compressor with a scotch yoke gate positioning system in accordance with an embodiment of the present invention.



FIGS. 26A-F are cross-sectional views of the inside of an embodiment of a rotary compressor with a contacting tip seal in a compression cycle in accordance with an embodiment of the present invention.



FIGS. 27A-F are cross-sectional views of the inside of an embodiment of a rotary compressor without a contacting tip seal in a compression cycle in accordance with another embodiment of the present invention.



FIG. 28 is perspective, cross-sectional view of a rotary compressor in accordance with an embodiment of the present invention.



FIG. 29 is a left-side view of an additional liquid injectors embodiment of the present invention.



FIG. 30 is a cross-section view of a rotor design in accordance with an embodiment of the present invention.



FIGS. 31A-D are cross-sectional views of rotor designs in accordance with various embodiments of the present invention.



FIGS. 32A and B are perspective and right-side views of a drive shaft, rotor, and gate in accordance with an embodiment of the present invention.



FIG. 33 is a perspective view of a gate with exhaust ports in accordance with an embodiment of the present invention.



FIGS. 34A and B are a perspective view and magnified view of a gate with notches, respectively, in accordance with an embodiment of the present invention.



FIG. 35 is a cross-sectional, perspective view a gate with a rolling tip in accordance with an embodiment of the present invention.



FIG. 36 is a cross-sectional front view of a gate with a liquid injection channel in accordance with an embodiment of the present invention.



FIG. 37 is a graph of the pressure-volume curve achieved by a compressor according to one or more embodiments of the present invention relative to adiabatic and isothermal compression.



FIGS. 38(a)-(d) show the sequential compression cycle and liquid coolant injection locations, directions, and timing according to one or more embodiments of the invention.





DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To the extent that the following terms are utilized herein, the following definitions are applicable:


Balanced rotation: the center of mass of the rotating mass is located on the axis of rotation.


Chamber volume: any volume that can contain fluids for compression.


Compressor: a device used to increase the pressure of a compressible fluid. The fluid can be either gas or vapor, and can have a wide molecular weight range.


Concentric: the center or axis of one object coincides with the center or axis of a second object


Concentric rotation: rotation in which one object's center of rotation is located on the same axis as the second object's center of rotation.


Positive displacement compressor: a compressor that collects a fixed volume of gas within a chamber and compresses it by reducing the chamber volume.


Proximate: sufficiently close to restrict fluid flow between high pressure and low pressure regions. Restriction does not need to be absolute; some leakage is acceptable.


Rotor: A rotating element driven by a mechanical force to rotate about an axis. As used in a compressor design, the rotor imparts energy to a fluid.


Rotary compressor: A positive-displacement compressor that imparts energy to the gas being compressed by way of an input shaft moving a single or multiple rotating elements



FIGS. 1 through 7 show external views of an embodiment of the present invention in which a rotary compressor includes spring backed cam drive gate positioning system. Main housing 100 includes a main casing 110 and end plates 120, each of which includes a hole through which drive shaft 140 passes axially. Liquid injector assemblies 130 are located on holes in the main casing 110. The main casing includes a hole for the inlet flange 160, and a hole for the gate casing 150.


Gate casing 150 is connected to and positioned below main casing 110 at a hole in main casing 110. The gate casing 150 is comprised of two portions: an inlet side 152 and an outlet side 154. Other embodiments of gate casing 150 may only consist of a single portion. As shown in FIG. 28, the outlet side 154 includes outlet ports 435, which are holes which lead to outlet valves 440. Alternatively, an outlet valve assembly may be used.


Referring back to FIGS. 1-7, the spring-backed cam drive gate positioning system 200 is attached to the gate casing 150 and drive shaft 140. The gate positioning system 200 moves gate 600 in conjunction with the rotation of rotor 500. A movable assembly includes gate struts 210 and cam struts 230 connected to gate support arm 220 and bearing support plate 156. The bearing support plate 156 seals the gate casing 150 by interfacing with the inlet and outlet sides through a bolted gasket connection. Bearing support plate 156 is shaped to seal gate casing 150, mount bearing housings 270 in a sufficiently parallel manner, and constrain compressive springs 280. In one embodiment, the interior of the gate casing 150 is hermetically sealed by the bearing support plate 156 with o-rings, gaskets, or other sealing materials. Other embodiments may support the bearings at other locations, in which case an alternate plate may be used to seal the interior of the gate casing. Shaft seals, mechanical seals, or other sealing mechanisms may be used to seal around the gate struts 210 which penetrate the bearing support plate 156 or other sealing plate. Bearing housings 270, also known as pillow blocks, are concentric to the gate struts 210 and the cam struts 230.


In the illustrated embodiment, the compressing structure comprises a rotor 500. However, according to alternative embodiments, alternative types of compressing structures (e.g., gears, screws, pistons, etc.) may be used in connection with the compression chamber to provide alternative compressors according to alternative embodiments of the invention.


Two cam followers 250 are located tangentially to each cam 240, providing a downward force on the gate. Drive shaft 140 turns cams 240, which transmits force to the cam followers 250. The cam followers 250 may be mounted on a through shaft, which is supported on both ends, or cantilevered and only supported on one end. The cam followers 250 are attached to cam follower supports 260, which transfer the force into the cam struts 230. As cams 240 turn, the cam followers 250 are pushed down, thus moving the cam struts 230 down. This moves the gate support arm 220 and the gate strut 210 down. This, in turn, moves the gate 600 down.


Springs 280 provide a restorative upward force to keep the gate 600 timed appropriately to seal against the rotor 500. As the cams 240 continue to turn and no longer effectuate a downward force on the cam followers 250, springs 280 provide an upward force. As shown in this embodiment, compression springs are utilized. As one of ordinary skill in the art would appreciate, tension springs and the shape of the bearing support plate 156 may be altered to provide for the desired upward or downward force. The upward force of the springs 280 pushes the cam follower support 260 and thus the gate support arm 220 up which in turn moves the gate 600 up.


Due to the varying pressure angle between the cam followers 250 and cams 240, the preferred embodiment may utilize an exterior cam profile that differs from the rotor 500 profile. This variation in profile allows for compensation for the changing pressure angle to ensure that the tip of the gate 600 remains proximate to the rotor 500 throughout the entire compression cycle.


Line A in FIGS. 3, 6, and 7 shows the location for the cross-sectional view of the compressor in FIG. 8. As shown in FIG. 8, the main casing 110 has a cylindrical shape. Liquid injector housings 132 are attached to, or may be cast as a part of, the main casing 110 to provide for openings in the rotor casing 400. Because it is cylindrically shaped in this embodiment, the rotor casing 400 may also be referenced as the cylinder. The interior wall defines a rotor casing volume 410 (also referred to as the compression chamber). The rotor 500 concentrically rotates with drive shaft 140 and is affixed to the drive shaft 140 by way of key 540 and press fit. Alternate methods for affixing the rotor 500 to the drive shaft 140, such as polygons, splines, or a tapered shaft may also be used.



FIG. 9 shows an embodiment of the present invention in which a timing belt with spring gate positioning system is utilized. This embodiment 290 incorporates two timing belts 292 each of which is attached to the drive shaft 140 by way of sheaves 294. The timing belts 292 are attached to secondary shafts 142 by way of sheaves 295. Gate strut springs 296 are mounted around gate struts. Rocker arms 297 are mounted to rocker arm supports 299. The sheaves 295 are connected to rocker arm cams 293 to push the rocker arms 297 down. As the inner rings push down on one side of the rocker arms 297, the other side pushes up against the gate support bar 298. The gate support bar 298 pushes up against the gate struts and gate strut springs 296. This moves the gate up. The springs 296 provide a downward force pushing the gate down.



FIGS. 10 through 17 show external views of a rotary compressor embodiment utilizing a dual cam follower gate positioning system. The main housing 100 includes a main casing 110 and end plates 120, each of which includes a hole through which a drive shaft 140 passes axially. Liquid injector assemblies 130 are located on holes in the main casing 110. The main casing 110 also includes a hole for the inlet flange 160 and a hole for the gate casing 150. The gate casing 150 is mounted to and positioned below the main casing 110 as discussed above.


A dual cam follower gate positioning system 300 is attached to the gate casing 150 and drive shaft 140. The dual cam follower gate positioning system 300 moves the gate 600 in conjunction with the rotation of the rotor 500. In a preferred embodiment, the size and shape of the cams is nearly identical to the rotor in cross-sectional size and shape. In other embodiments, the rotor, cam shape, curvature, cam thickness, and variations in the thickness of the lip of the cam may be adjusted to account for variations in the attack angle of the cam follower. Further, large or smaller cam sizes may be used. For example, a similar shape but smaller size cam may be used to reduce roller speeds.


A movable assembly includes gate struts 210 and cam struts 230 connected to gate support arm 220 and bearing support plate 156. In this embodiment, the bearing support plate 157 is straight. As one of ordinary skill in the art would appreciate, the bearing support plate can utilize different geometries, including structures designed to or not to perform sealing of the gate casing 150. In this embodiment, the bearing support plate 157 serves to seal the bottom of the gate casing 150 through a bolted gasket connection. Bearing housings 270, also known as pillow blocks, are mounted to bearing support plate 157 and are concentric to the gate struts 210 and the cam struts 230. In certain embodiments, the components comprising this movable assembly may be optimized to reduce weight, thereby reducing the force necessary to achieve the necessary acceleration to keep the tip of gate 600 proximate to the rotor 500. Weight reduction could additionally and/or alternatively be achieved by removing material from the exterior of any of the moving components, as well as by hollowing out moving components, such as the gate struts 210 or the gate 600.


Drive shaft 140 turns cams 240, which transmit force to the cam followers 250, including upper cam followers 252 and lower cam followers 254. The cam followers 250 may be mounted on a through shaft, which is supported on both ends, or cantilevered and only supported on one end. In this embodiment, four cam followers 250 are used for each cam 240. Two lower cam followers 252 are located below and follow the outside edge of the cam 240. They are mounted using a through shaft. Two upper cam followers 254 are located above the previous two and follow the inside edge of the cams 240. They are mounted using a cantilevered connection.


The cam followers 250 are attached to cam follower supports 260, which transfer the force into the cam struts 230. As the cams 240 turn, the cam struts 230 move up and down. This moves the gate support arm 220 and gate struts 210 up and down, which in turn, moves the gate 600 up and down.


Line A in FIGS. 11, 12, 15, and 16 show the location for the cross-sectional view of the compressor in FIG. 17. As shown in FIG. 17, the main casing 110 has a cylindrical shape. Liquid injector housings 132 are attached to or may be cast as a part of the main casing 110 to provide for openings in the rotor casing 400. The rotor 500 concentrically rotates around drive shaft 140.


An embodiment using a belt driven system 310 is shown in FIG. 18. Timing belts 292 are connected to the drive shaft 140 by way of sheaves 294. The timing belts 292 are each also connected to secondary shafts 142 by way of another set of sheaves 295. The secondary shafts 142 drive the external cams 240, which are placed below the gate casing 150 in this embodiment. Sets of upper and lower cam followers 254 and 252 are applied to the cams 240, which provide force to the movable assembly including gate struts 210 and gate support arm 220. As one of ordinary skill in the art would appreciate, belts may be replaced by chains or other materials.


An embodiment of the present invention using an offset gate guide system is shown in FIGS. 19 through 22 and 33. Outlet of the compressed gas and injected fluid is achieved through a ported gate system 602 comprised of two parts bolted together to allow for internal lightening features. Fluid passes through channels 630 in the upper portion of the gate 602 and travels to the lengthwise sides to outlet through an exhaust port 344 in a timed manner with relation to the angle of rotation of the rotor 500 during the cycle. Discrete point spring-backed scraper seals 326 provide sealing of the gate 602 in the single piece gate casing 336. Liquid injection is achieved through a variety of flat spray nozzles 322 and injector nozzles 130 across a variety of liquid injector port 324 locations and angles.


Reciprocating motion of the two-piece gate 602 is controlled through the use of an offset spring-backed cam follower control system 320 to achieve gate motion in concert with rotor rotation. Single cams 342 drive the gate system downwards through the transmission of force on the cam followers 250 through the cam struts 338. This results in controlled motion of the crossarm 334, which is connected by bolts (some of which are labeled as 328) with the two-piece gate 602. The crossarm 334 mounted linear bushings 330, which reciprocate along the length of cam shafts 332, control the motion of the gate 602 and the crossarm 334. The cam shafts 332 are fixed in a precise manner to the main casing through the use of cam shaft support blocks 340. Compression springs 346 are utilized to provide a returning force on the crossarm 334, allowing the cam followers 250 to maintain constant rolling contact with the cams, thereby achieving controlled reciprocating motion of the two-piece gate 602.



FIG. 23 shows an embodiment using a linear actuator system 350 for gate positioning. A pair of linear actuators 352 is used to drive the gate. In this embodiment, it is not necessary to mechanically link the drive shaft to the gate as with other embodiments. The linear actuators 352 are controlled so as to raise and lower the gate in accordance with the rotation of the rotor. The actuators may be electronic, hydraulic, belt-driven, electromagnetic, gas-driven, variable-friction, or other means. The actuators may be computer controlled or controlled by other means.



FIGS. 24A and B show a magnetic drive system 360. The gate system may be driven, or controlled, in a reciprocating motion through the placement of magnetic field generators, whether they are permanent magnets or electromagnets, on any combination of the rotor 500, gate 600, and/or gate casing 150. The purpose of this system is to maintain a constant distance from the tip of the gate 600 to the surface of the rotor 500 at all angles throughout the cycle. In a preferred magnetic system embodiment, permanent magnets 366 are mounted into the ends of the rotor 500 and retained. In addition, permanent magnets 364 are installed and retained in the gate 600. Poles of the magnets are aligned so that the magnetic force generated between the rotor's magnets 366 and the gate's magnets 364 is a repulsive force, forcing the gate 600 down throughout the cycle to control its motion and maintain constant distance. To provide an upward, returning force on the gate 600, additional magnets (not shown) are installed into the bottom of the gate 600 and the bottom of the gate casing 150 to provide an additional repulsive force. The magnetic drive systems are balanced to precisely control the gate's reciprocating motion.


Alternative embodiments may use an alternate pole orientation to provide attractive forces between the gate and rotor on the top portion of the gate and attractive forces between the gate and gate casing on the bottom portion of the gate. In place of the lower magnet system, springs may be used to provide a repulsive force. In each embodiment, electromagnets may be used in place of permanent magnets. In addition, switched reluctance electromagnets may also be utilized. In another embodiment, electromagnets may be used only in the rotor and gate. Their poles may switch at each inflection point of the gate's travel during its reciprocating cycle, allowing them to be used in an attractive and repulsive method.


Alternatively, direct hydraulic or indirect hydraulic (hydropneumatic) can be used to apply motive force/energy to the gate to drive it and position it adequately. Solenoid or other flow control valves can be used to feed and regulate the position and movement of the hydraulic or hydropneumatic elements. Hydraulic force may be converted to mechanical force acting on the gate through the use of a cylinder based or direct hydraulic actuators using membranes/diaphragms.



FIG. 25 shows an embodiment using a scotch yoke gate positioning system 370. Here, a pair of scotch yokes 372 is connected to the drive shaft and the bearing support plate. A roller rotates at a fixed radius with respect to the shaft. The roller follows a slot within the yoke 372, which is constrained to a reciprocating motion. The yoke geometry can be manipulated to a specific shape that will result in desired gate dynamics.


As one of skill in the art would appreciate, these alternative drive mechanisms do not require any particular number of linkages between the drive shaft and the gate. For example, a single spring, belt, linkage bar, or yoke could be used. Depending on the design implementation, more than two such elements could be used.



FIGS. 26A-26F show a compression cycle of an embodiment utilizing a tip seal 620. As the drive shaft 140 turns, the rotor 500 and gate strut 210 push up gate 600 so that it is timed with the rotor 500. As the rotor 500 turns clockwise, the gate 600 rises up until the rotor 500 is in the 12 o'clock position shown in FIG. 26C. As the rotor 500 continues to turn, the gate 600 moves downward until it is back at the 6 o'clock position in FIG. 26F. The gate 600 separates the portion of the cylinder that is not taken up by rotor 500 into two components: an intake component 412 and a compression component 414. In one embodiment, tip seal 620 may not be centered within the gate 600, but may instead be shifted towards one side so as to minimize the area on the top of the gate on which pressure may exert a downwards force on the gate. This may also have the effect of minimizing the clearance volume of the system. In another embodiment, the end of the tip seal 620 proximate to the rotor 500 may be rounded, so as to accommodate the varying contact angle that will be encountered as the tip seal 620 contacts the rotor 500 at different points in its rotation.



FIGS. 26A-F depict steady state operation. Accordingly, in FIG. 26A, where the rotor 500 is in the 6 o'clock position, the compression volume 414, which constitutes a subset of the rotor casing volume 410, already has received fluid. In FIG. 26B, the rotor 500 has turned clockwise and gate 600 has risen so that the tip seal 620 makes contact with the rotor 500 to separate the intake volume 412, which also constitutes a subset of the rotor casing volume 410, from the compression volume 414. Embodiments using the roller tip 650 discussed below instead of tip seal 620 would operate similarly. As the rotor 500 turns, as shown further in FIGS. 26C-E, the intake volume 412 increases, thereby drawing in more fluid from inlet 420, while the compression volume 414 decreases. As the volume of the compression volume 414 decreases, the pressure increases. The pressurized fluid is then expelled by way of an outlet 430. At a point in the compression cycle when a desired high pressure is reached, the outlet valve opens and the high pressure fluid can leave the compression volume 414. In this embodiment, the valve outputs both the compressed gas and the liquid injected into the compression chamber.



FIGS. 27A-27F show an embodiment in which the gate 600 does not use a tip seal. Instead, the gate 600 is timed to be proximate to the rotor 500 as it turns. The close proximity of the gate 600 to the rotor 500 leaves only a very small path for high pressure fluid to escape. Close proximity in conjunction with the presence of liquid (due to the liquid injectors 136 or an injector placed in the gate itself) allow the gate 600 to effectively create an intake fluid component 412 and a compression component 414. Embodiments incorporating notches 640 would operate similarly.



FIG. 28 shows a cross-sectional perspective view of the rotor casing 400, the rotor 500, and the gate 600. The inlet port 420 shows the path that gas can enter. The outlet 430 is comprised of several holes that serve as outlet ports 435 that lead to outlet valves 440. The gate casing 150 consists of an inlet side 152 and an outlet side 154. A return pressure path (not shown) may be connected to the inlet side 152 of the gate casing 150 and the inlet port 420 to ensure that there is no back pressure build up against gate 600 due to leakage through the gate seals. As one of ordinary skill in the art would appreciate, it is desirable to achieve a hermetic seal, although perfect hermetic sealing is not necessary.


In alternate embodiments, the outlet ports 435 may be located in the rotor casing 400 instead of the gate casing 150. They may be located at a variety of different locations within the rotor casing. The outlet valves 440 may be located closer to the compression chamber, effectively minimizing the volume of the outlet ports 430, to minimize the clearance volume related to these outlet ports. A valve cartridge may be used which houses one or more outlet valves 440 and connects directly to the rotor casing 400 or gate casing 150 to align the outlet valves 440 with outlet ports 435. This may allow for ease of installing and removing the outlet valves 440.



FIG. 29 shows an alternative embodiment in which flat spray liquid injector housings 170 are located on the main casing 110 at approximately the 3 o'clock position. These injectors can be used to inject liquid directly onto the inlet side of the gate 600, ensuring that it does not reach high temperatures. These injectors also help to provide a coating of liquid on the rotor 500, helping to seal the compressor.


As discussed above, the preferred embodiments utilize a rotor that concentrically rotates within a rotor casing. In the preferred embodiment, the rotor 500 is a right cylinder with a non-circular cross-section that runs the length of the main casing 110. FIG. 30 shows a cross-sectional view of the sealing and non-sealing portions of the rotor 500. The profile of the rotor 500 is comprised of three sections. The radii in sections I and III are defined by a cycloidal curve. This curve also represents the rise and fall of the gate and defines an optimum acceleration profile for the gate. Other embodiments may use different curve functions to define the radius such as a double harmonic function. Section II employs a constant radius 570, which corresponds to the maximum radius of the rotor. The minimum radius 580 is located at the intersection of sections I and III, at the bottom of rotor 500. In a preferred embodiment, Φ is 23.8 degrees. In alternative embodiments, other angles may be utilized depending on the desired size of the compressor, the desired acceleration of the gate, and desired sealing area.


The radii of the rotor 500 in the preferred embodiment can be calculated using the following functions:







r


(
t
)


=

{





r
I

=


r
min

+

h


[



t
I

T

+

sin


(


2

π






t
I


T

)



]










r
II

=

r
max








r
III

=


r
min

+

h


[



t
III

T

+

sin


(


2

π






t
III


T

)



]












In a preferred embodiment, the rotor 500 is symmetrical along one axis. It may generally resemble a cross-sectional egg shape. The rotor 500 includes a hole 530 in which the drive shaft 140 and a key 540 may be mounted. The rotor 500 has a sealing section 510, which is the outer surface of the rotor 500 corresponding to section II, and a non-sealing section 520, which is the outer surface of the rotor 500 corresponding to sections I and III. The sections I and III have a smaller radius than sections II creating a compression volume. The sealing portion 510 is shaped to correspond to the curvature of the rotor casing 400, thereby creating a dwell seal that effectively minimizes communication between the outlet 430 and inlet 420. Physical contact is not required for the dwell seal. Instead, it is sufficient to create a tortuous path that minimizes the amount of fluid that can pass through. In a preferred embodiment, the gap between the rotor and the casing in this embodiment is less than 0.008 inches. As one of ordinary skill in the art would appreciate, this gap may be altered depending on tolerances, both in machining the rotor 500 and rotor housing 400, temperature, material properties, and other specific application requirements.


Additionally, as discussed below, liquid is injected into the compression chamber. By becoming entrained in the gap between the sealing portion 510 and the rotor casing 400, the liquid can increase the effectiveness of the dwell seal.


As shown in FIG. 31A, the rotor 500 is balanced with cut out shapes and counterweights. Holes, some of which are marked as 550, lighten the rotor 500. These lightening holes may be filled with a low density material to ensure that liquid cannot encroach into the rotor interior. Alternatively, caps may be placed on the ends of rotor 500 to seal the lightening holes. Counterweights, one of which is labeled as 560, are made of a denser material than the remainder of the rotor 500. The shapes of the counterweights can vary and do not need to be cylindrical.


The rotor design provides several advantages. As shown in the embodiment of FIG. 31A, the rotor 500 includes 7 cutout holes 550 on one side and two counterweights 560 on the other side to allow the center of mass to match the center of rotation. An opening 530 includes space for the drive shaft and a key. This weight distribution is designed to achieve balanced, concentric motion. The number and location of cutouts and counterweights may be changed depending on structural integrity, weight distribution, and balanced rotation parameters. In various embodiments, cutouts and/or counterweights or neither may be used required to achieve balanced rotor rotation.


The cross-sectional shape of the rotor 500 allows for concentric rotation about the drive shaft's axis of rotation, a dwell seal 510 portion, and open space on the non-sealing side for increased gas volume for compression. Concentric rotation provides for rotation about the drive shaft's principal axis of rotation and thus smoother motion and reduced noise.


An alternative rotor design 502 is shown in FIG. 31B. In this embodiment, a different arc of curvature is implemented utilizing three holes 550 and a circular opening 530. Another alternative design 504 is shown in FIG. 31C. Here, a solid rotor shape is used and a larger hole 530 (for a larger drive shaft) is implemented. Yet another alternative rotor design 506 is shown in FIG. 31D incorporating an asymmetrical shape, which would smooth the volume reduction curve, allowing for increased time for heat transfer to occur at higher pressures. Alternative rotor shapes may be implemented for different curvatures or needs for increased volume in the compression chamber.


The rotor surface may be smooth in embodiments with contacting tip seals to minimize wear on the tip seal. In alternative embodiments, it may be advantageous to put surface texture on the rotor to create turbulence that may improve the performance of non-contacting seals. In other embodiments, the rotor casing's interior cylindrical wall may further be textured to produce additional turbulence, both for sealing and heat transfer benefits. This texturing could be achieved through machining of the parts or by utilizing a surface coating. Another method of achieving the texture would be through blasting with a waterjet, sandblast, or similar device to create an irregular surface.


The main casing 110 may further utilize a removable cylinder liner. This liner may feature microsurfacing to induce turbulence for the benefits noted above. The liner may also act as a wear surface to increase the reliability of the rotor and casing. The removable liner could be replaced at regular intervals as part of a recommended maintenance schedule. The rotor may also include a liner. Sacrifical or wear-in coatings may be used on the rotor 500 or rotor casing 400 to correct for manufacturing defects in ensuring the preferred gap is maintained along the sealing portion 510 of the rotor 500.


The exterior of the main casing 110 may also be modified to meet application specific parameters. For example, in subsea applications, the casing may require to be significantly thickened to withstand exterior pressure, or placed within a secondary pressure vessel. Other applications may benefit from the exterior of the casing having a rectangular or square profile to facilitate mounting exterior objects or stacking multiple compressors. Liquid may be circulated in the casing interior to achieve additional heat transfer or to equalize pressure in the case of subsea applications for example.


As shown in FIGS. 32A and B, the combination of the rotor 500 (here depicted with rotor end caps 590), the gate 600, and drive shaft 140, provide for a more efficient manner of compressing fluids in a cylinder. The gate is aligned along the length of the rotor to separate and define the inlet portion and compression portion as the rotor turns.


The drive shaft 140 is mounted to endplates 120 in the preferred embodiment using one spherical roller bearing in each endplate 120. More than one bearing may be used in each endplate 120, in order to increase total load capacity. A grease pump (not shown) is used to provide lubrication to the bearings. Various types of other bearings may be utilized depending on application specific parameters, including roller bearings, ball bearings, needle bearings, conical bearings, cylindrical bearings, journal bearings, etc. Different lubrication systems using grease, oil, or other lubricants may also be used. Further, dry lubrication systems or materials may be used. Additionally, applications in which dynamic imbalance may occur may benefit from multi-bearing arrangements to support stray axial loads.


Operation of gates in accordance with embodiments of the present invention are shown in FIGS. 8, 17, 22, 24B, 26A-F, 27A-F, 28, 32A-B, and 33-36. As shown in FIGS. 26A-F and 27A-F, gate 600 creates a pressure boundary between an intake volume 412 and a compression volume 414. The intake volume 412 is in communication with the inlet 420. The compression volume 414 is in communication with the outlet 430. Resembling a reciprocating, rectangular piston, the gate 600 rises and falls in time with the turning of the rotor 500.


The gate 600 may include an optional tip seal 620 that makes contact with the rotor 500, providing an interface between the rotor 500 and the gate 600. Tip seal 620 consists of a strip of material at the tip of the gate 600 that rides against rotor 500. The tip seal 620 could be made of different materials, including polymers, graphite, and metal, and could take a variety of geometries, such as a curved, flat, or angled surface. The tip seal 620 may be backed by pressurized fluid or a spring force provided by springs or elastomers. This provides a return force to keep the tip seal 620 in sealing contact with the rotor 500.


Different types of contacting tips may be used with the gate 600. As shown in FIG. 35, a roller tip 650 may be used. The roller tip 650 rotates as it makes contact with the turning rotor 500. Also, tips of differing strengths may be used. For example, a tip seal 620 or roller tip 650 may be made of softer metal that would gradually wear down before the rotor 500 surfaces would wear.


Alternatively, a non-contacting seal may be used. Accordingly, the tip seal may be omitted. In these embodiments, the topmost portion of the gate 600 is placed proximate, but not necessarily in contact with, the rotor 500 as it turns. The amount of allowable gap may be adjusted depending on application parameters.


As shown in FIGS. 34A and 34B, in an embodiment in which the tip of the gate 600 does not contact the rotor 500, the tip may include notches 640 that serve to keep gas pocketed against the tip of the gate 600. The entrained fluid, in either gas or liquid form, assists in providing a non-contacting seal. As one of ordinary skill in the art would appreciate, the number and size of the notches is a matter of design choice dependent on the compressor specifications.


Alternatively, liquid may be injected from the gate itself. As shown in FIG. 36, a cross-sectional view of a portion of a gate, one or more channels 660 from which a fluid may pass may be built into the gate. In one such embodiment, a liquid can pass through a plurality of channels 660 to form a liquid seal between the topmost portion of the gate 600 and the rotor 500 as it turns. In another embodiment, residual compressed fluid may be inserted through one or more channels 660. Further still, the gate 600 may be shaped to match the curvature of portions of the rotor 500 to minimize the gap between the gate 600 and the rotor 500.


Preferred embodiments enclose the gate in a gate casing. As shown in FIGS. 8 and 17, the gate 600 is encompassed by the gate casing 150, including notches, one of which is shown as item 158. The notches hold the gate seals, which ensure that the compressed fluid will not release from the compression volume 414 through the interface between gate 600 and gate casing 150 as gate 600 moves up and down. The gate seals may be made of various materials, including polymers, graphite or metal. A variety of different geometries may be used for these seals. Various embodiments could utilize different notch geometries, including ones in which the notches may pass through the gate casing, in part or in full.


In alternate embodiments, the seals could be placed on the gate 600 instead of within the gate casing 150. The seals would form a ring around the gate 600 and move with the gate relative to the casing 150, maintaining a seal against the interior of the gate casing 150. The location of the seals may be chosen such that the center of pressure on the gate 600 is located on the portion of the gate 600 inside of the gate casing 150, thus reducing or eliminating the effect of a cantilevered force on the portion of the gate 600 extending into the rotor casing 400. This may help eliminate a line contact between the gate 600 and gate casing 150 and instead provide a surface contact, allowing for reduced friction and wear. One or more wear plates may be used on the gate 600 to contact the gate casing 150. The location of the seals and wear plates may be optimized to ensure proper distribution of forces across the wear plates.


The seals may use energizing forces provided by springs or elastomers with the assembly of the gate casing 150 inducing compression on the seals. Pressurized fluid may also be used to energize the seals.


The gate 600 is shown with gate struts 210 connected to the end of the gate. In various embodiments, the gate 600 may be hollowed out such that the gate struts 210 can connect to the gate 600 closer to its tip. This may reduce the amount of thermal expansion encountered in the gate 600. A hollow gate also reduces the weight of the moving assembly and allows oil or other lubricants and coolants to be splashed into the interior of the gate to maintain a cooler temperature. The relative location of where the gate struts 210 connect to the gate 600 and where the gate seals are located may be optimized such that the deflection modes of the gate 600 and gate struts 210 are equal, allowing the gate 600 to remain parallel to the interior wall of the gate casing 150 when it deflects due to pressure, as opposed to rotating from the pressure force. Remaining parallel may help to distribute the load between the gate 600 and gate casing 150 to reduce friction and wear.


A rotor face seal may also be placed on the rotor 500 to provide for an interface between the rotor 500 and the endplates 120. An outer rotor face seal is placed along the exterior edge of the rotor 500, preventing fluid from escaping past the end of the rotor 500. A secondary inner rotor face seal is placed on the rotor face at a smaller radius to prevent any fluid that escapes past the outer rotor face seal from escaping the compressor entirely. This seal may use the same or other materials as the gate seal. Various geometries may be used to optimize the effectiveness of the seals. These seals may use energizing forces provided by springs, elastomers or pressurized fluid. Lubrication may be provided to these rotor face seals by injecting oil or other lubricant through ports in the endplates 120.


Along with the seals discussed herein, the surfaces those seals contact, known as counter-surfaces, may also be considered. In various embodiments, the surface finish of the counter-surface may be sufficiently smooth to minimize friction and wear between the surfaces. In other embodiments, the surface finish may be roughened or given a pattern such as cross-hatching to promote retention of lubricant or turbulence of leaking fluids. The counter-surface may be composed of a harder material than the seal to ensure the seal wears faster than the counter-surface, or the seal may be composed of a harder material than the counter-surface to ensure the counter-surface wears faster than the seal. The desired physical properties of the counter-surface (surface roughness, hardness, etc.) may be achieved through material selection, material finishing techniques such as quenching, tempering, or work hardening, or selection and application of coatings that achieve the desired characteristics. Final manufacturing processes, such as surface grinding, may be performed before or after coatings are applied. In various embodiments, the counter-surface material may be steel or stainless steel. The material may be hardened via quenching or tempering. A coating may be applied, which could be chrome, titanium nitride, silicon carbide, or other materials.


Minimizing the possibility of fluids leaking to the exterior of the main housing 100 is desirable. Various seals, such as gaskets and o-rings, are used to seal external connections between parts. For example, in a preferred embodiment, a double o-ring seal is used between the main casing 110 and endplates 120. Further seals are utilized around the drive shaft 140 to prevent leakage of any fluids making it past the rotor face seals. A lip seal is used to seal the drive shaft 140 where it passes through the endplates 120. In various embodiments, multiple seals may be used along the drive shaft 140 with small gaps between them to locate vent lines and hydraulic packings to reduce or eliminate gas leakage exterior to the compression chamber. Other forms of seals could also be used, such as mechanical or labyrinth seals.


It is desirable to achieve near isothermal compression. To provide cooling during the compression process, liquid injection is used. In preferred embodiments, the liquid is atomized to provide increased surface area for heat absorption. In other embodiments, different spray applications or other means of injecting liquids may be used.


Liquid injection is used to cool the fluid as it is compressed, increasing the efficiency of the compression process. Cooling allows most of the input energy to be used for compression rather than heat generation in the gas. The liquid has dramatically superior heat absorption characteristics compared to gas, allowing the liquid to absorb heat and minimize temperature increase of the working fluid, achieving near isothermal compression. As shown in FIGS. 8 and 17, liquid injector assemblies 130 are attached to the main casing 110. Liquid injector housings 132 include an adapter for the liquid source 134 (if it is not included with the nozzle) and a nozzle 136. Liquid is injected by way of a nozzle 136 directly into the rotor casing volume 410.


The amount and timing of liquid injection may be controlled by a variety of implements including a computer-based controller capable of measuring the liquid drainage rate, liquid levels in the chamber, and/or any rotational resistance due to liquid accumulation through a variety of sensors. Valves or solenoids may be used in conjunction with the nozzles to selectively control injection timing. Variable orifice control may also be used to regulate the amount of liquid injection and other characteristics.


Analytical and experimental results are used to optimize the number, location, and spray direction of the injectors 136. These injectors 136 may be located in the periphery of the cylinder. Liquid injection may also occur through the rotor or gate. The current embodiment of the design has two nozzles located at 12 o'clock and 10 o'clock. Different application parameters will also influence preferred nozzle arrays.


Because the heat capacity of liquids is typically much higher than gases, the heat is primarily absorbed by the liquid, keeping gas temperatures lower than they would be in the absence of such liquid injection.


When a fluid is compressed, the pressure times the volume raised to a polytropic exponent remains constant throughout the cycle, as seen in the following equation:

P*Vn=Constant


In polytropic compression, two special cases represent the opposing sides of the compression spectrum. On the high end, adiabatic compression is defined by a polytropic constant of n=1.4 for air, or n=1.28 for methane. Adiabatic compression is characterized by the complete absence of cooling of the working fluid (isentropic compression is a subset of adiabatic compression in which the process is reversible). This means that as the volume of the fluid is reduced, the pressure and temperature each rise accordingly. It is an inefficient process due to the exorbitant amount of energy wasted in the generation of heat in the fluid, which often needs to be cooled down again later. Despite being an inefficient process, most conventional compression technology, including reciprocating piston and centrifugal type compressors are essentially adiabatic. The other special case is isothermal compression, where n=1. It is an ideal compression cycle in which all heat generated in the fluid is transmitted to the environment, maintaining a constant temperature in the working fluid. Although it represents an unachievable perfect case, isothermal compression is useful in that it provides a lower limit to the amount of energy required to compress a fluid.



FIG. 37 shows a sample pressure-volume (P-V) curve comparing several different compression processes. The isothermal curve shows the theoretically ideal process. The adiabatic curve represents an adiabatic compression cycle, which is what most conventional compressor technologies follow. Since the area under the P-V curve represents the amount of work required for compression, approaching the isothermal curve means that less work is needed for compression. A model of one or more compressors according to various embodiments of the present invention is also shown, nearly achieving as good of results as the isothermal process. According to various embodiments, the above-discussed coolant injection facilitates the near isothermal compression through absorption of heat by the coolant. Not only does this near-isothermal compression process require less energy, at the end of the cycle gas temperatures are much lower than those encountered with traditional compressors. According to various embodiments, such a reduction in compressed working fluid temperature eliminates the use of or reduces the size of expensive and efficiency-robbing after-coolers.


Embodiments of the present invention achieve these near-isothermal results through the above-discussed injection of liquid coolant. Compression efficiency is improved according to one or more embodiments because the working fluid is cooled by injecting liquid directly into the chamber during the compression cycle. According to various embodiments, the liquid is injected directly into the area of the compression chamber where the gas is undergoing compression.


Rapid heat transfer between the working fluid and the coolant directly at the point of compression may facilitate high pressure ratios. That leads to several aspects of various embodiments of the present invention that may be modified to improve the heat transfer and raise the pressure ratio.


One consideration is the heat capacity of the liquid coolant. The basic heat transfer equation is as follows:

Q=mcpΔT


where Q is the heat,

    • m is mass,
    • ΔT is change in temperature, and
    • cp is the specific heat.


      The higher the specific heat of the coolant, the more heat transfer that will occur.


Choosing a coolant is sometimes more complicated than simply choosing a liquid with the highest heat capacity possible. Other factors, such as cost, availability, toxicity, compatibility with working fluid, and others can also be considered. In addition, other characteristics of the fluid, such as viscosity, density, and surface tension affect things like droplet formation which, as will be discussed below, also affect cooling performance.


According to various embodiments, water is used as the cooling liquid for air compression. For methane compression, various liquid hydrocarbons may be effective coolants, as well as triethylene glycol.


Another consideration is the relative velocity of coolant to the working fluid. Movement of the coolant relative to the working fluid at the location of compression of the working fluid (which is the point of heat generation) enhances heat transfer from the working fluid to the coolant. For example, injecting coolant at the inlet of a compressor such that the coolant is moving with the working fluid by the time compression occurs and heat is generated will cool less effectively than if the coolant is injected in a direction perpendicular to or counter to the flow of the working fluid adjacent the location of liquid coolant injection. FIGS. 38(a)-(d) show a schematic of the sequential compression cycle in a compressor according to an embodiment of the invention. The dotted arrows in FIG. 38(c) show the injection locations, directions, and timing used according to various embodiments of the present invention to enhance the cooling performance of the system.


As shown in FIG. 38(a), the compression stroke begins with a maximum working fluid volume (shown in gray) within the compression chamber. In the illustrated embodiment, the beginning of the compression stroke occurs when the rotor is at the 6 o'clock position (in an embodiment in which the gate is disposed at 6 o'clock with the inlet on the left of the gate and the outlet on the right of the gate as shown in FIGS. 38(a)-(d)). In FIG. 38(b), compression has started, the rotor is at the 9 o'clock position, and cooling liquid is injected into the compression chamber. In FIG. 38(c), about 50% of the compression stroke has occurred, and the rotor is disposed at the 12 o'clock position. FIG. 38(d) illustrates a position (3 o'clock) in which the compression stroke is nearly completed (e.g., about 95% complete). Compression is ultimately completed when the rotor returns to the position shown in FIG. 38(a).


As shown in FIGS. 38(b) and (c), dotted arrows illustrate the timing, location, and direction of the coolant injection.


According to various embodiments, coolant injection occurs during only part of the compression cycle. For example, in each compression cycle/stroke, the coolant injection may begin at or after the first 10, 20, 30, 40, 50, 60 and/or 70% of the compression stroke/cycle (the stroke/cycle being measured in terms of volumetric compression). According to various embodiments, the coolant injection may end at each nozzle shortly before the rotor sweeps past the nozzle (e.g., resulting in sequential ending of the injection at each nozzle (clockwise as illustrated in FIG. 38)). According to various alternative embodiments, coolant injection occurs continuously throughout the compression cycle, regardless of the rotor position.


As shown in FIGS. 38(b) and (c), the nozzles inject the liquid coolant into the chamber perpendicular to the sweeping direction of the rotor (i.e., toward the rotor's axis of rotation, in the inward radial direction relative to the rotor's axis of rotation). However, according to alternative embodiments, the direction of injection may be oriented so as to aim more upstream (e.g., at an acute angle relative to the radial direction such that the coolant is injected in a partially counter-flow direction relative to the sweeping direction of the rotor). According to various embodiments, the acute angle may be anywhere between 0 and 90 degrees toward the upstream direction relative to the radial line extending from the rotor's axis of rotation to the injector nozzle. Such an acute angle may further increase the velocity of the coolant relative to the surrounding working fluid, thereby further enhancing the heat transfer.


A further consideration is the location of the coolant injection, which is defined by the location at which the nozzles inject coolant into the compression chamber. As shown in FIGS. 38(b) and (c), coolant injection nozzles are disposed at about 1, 2, 3, and 4 o'clock. However, additional and/or alternative locations may be chosen without deviating from the scope of the present invention. According to various embodiments, the location of injection is positioned within the compression volume (shown in gray in FIG. 38) that exists during the compressor's highest rate of compression (in terms of Δvolume/time or Δvolume/degree-of-rotor-rotation, which may or may not coincide). In the embodiment illustrated in FIG. 38, the highest rate of compression occurs around where the rotor is rotating from the 12 o'clock position shown in FIG. 38(c) to the 3 o'clock position shown in FIG. 38(d). This location is dependent on the compression mechanism being employed and in various embodiments of the invention may vary.


As one skilled in the art could appreciate, the number and location of the nozzles may be selected based on a variety of factors. The number of nozzles may be as few as 1 or as many as 256 or more. According to various embodiments, the compressor includes (a) at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50, 75, 100, 125, 150, 175, 200, 225, and/or 250 nozzles, (b) less than 400, 300, 275, 250, 225, 200, 175, 150, 125, 100, 75, 50, 40, 30, 20, 15, and/or 10 nozzles, (c) between 1 and 400 nozzles, and/or (d) any range of nozzles bounded by such numbers of any ranges therebetween. According to various embodiments, liquid coolant injection may be avoided altogether such that no nozzles are used. Along with varying the location along the angle of the rotor casing, a different number of nozzles may be installed at various locations along the length of the rotor casing. In certain embodiments, the same number of nozzles will be placed along the length of the casing at various angles. In other embodiments, nozzles may be scattered/staggered at different locations along the casing's length such that a nozzle at one angle may not have another nozzle at exactly the same location along the length at other angles. In various embodiments, a manifold may be used in which one or more nozzle is installed that connects directly to the rotor casing, simplifying the installation of multiple nozzles and the connection of liquid lines to those nozzles.


Coolant droplet size is a further consideration. Because the rate of heat transfer is linearly proportional to the surface area of liquid across which heat transfer can occur, the creation of smaller droplets via the above-discussed atomizing nozzles improves cooling by increasing the liquid surface area and allowing heat transfer to occur more quickly. Reducing the diameter of droplets of coolant in half (for a given mass) increases the surface area by a factor of two and thus improves the rate of heat transfer by a factor of 2. In addition, for small droplets the rate of convection typically far exceeds the rate of conduction, effectively creating a constant temperature across the droplet and removing any temperature gradients. This may result in the full mass of liquid being used to cool the gas, as opposed to larger droplets where some mass at the center of the droplet may not contribute to the cooling effect. Based on that evidence, it appears advantageous to inject as small of droplets as possible. However, droplets that are too small, when injected into the high density, high turbulence region as shown in FIGS. 38(b) and (c), run the risk of being swept up by the working fluid and not continuing to move through the working fluid and maintain high relative velocity. Small droplets may also evaporate and lead to deposition of solids on the compressor's interior surfaces. Other extraneous factors also affect droplet size decisions, such as power losses of the coolant being forced through the nozzle and amount of liquid that the compressor can handle internally.


According to various embodiments, average droplet sizes of between 50 and 500 microns, between 50 and 300 microns, between 100 and 150 microns, and/or any ranges within those ranges, may be fairly effective.


The mass of the coolant liquid is a further consideration. As evidenced by the heat equation shown above, more mass (which is proportional to volume) of coolant will result in more heat transfer. However, the mass of coolant injected may be balanced against the amount of liquid that the compressor can accommodate, as well as extraneous power losses required to handle the higher mass of coolant. According to various embodiments, between 1 and 100 gallons per minute (gpm), between 3 and 40 gpm, between 5 and 25 gpm, between 7 and 10 gpm, and/or any ranges therebetween may provide an effective mass flow rate (averaged throughout the compression stroke despite the non-continuous injection according to various embodiments). According to various embodiments, the volumetric flow rate of liquid coolant into the compression chamber may be at least 1, 2, 3, 4, 5, 6, 7, 8, 9, and/or 10 gpm. According to various embodiments, flow rate of liquid coolant into the compression chamber may be less than 100, 80, 60, 50, 40, 30, 25, 20, 15, and/or 10 gpm.


The nozzle array may be designed for a high flow rate of greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and/or 15 gallons per minute and be capable of extremely small droplet sizes of less than 500 and/or 150 microns or less at a low differential pressure of less than 400, 300, 200, and/or 100 psi. Two exemplary nozzles are Spraying Systems Co. Part Number: 1/4HHSJ-SS12007 and Bex Spray Nozzles Part Number: 1/4YS12007. Other non-limiting nozzles that may be suitable for use in various embodiments include Spraying Systems Co. Part Number 1/4LN-SS14 and 1/4LN-SS8. The preferred flow rate and droplet size ranges will vary with application parameters. Alternative nozzle styles may also be used. For example, one embodiment may use micro-perforations in the cylinder through which to inject liquid, counting on the small size of the holes to create sufficiently small droplets. Other embodiments may include various off the shelf or custom designed nozzles which, when combined into an array, meet the injection requirements necessary for a given application.


According to various embodiments, one, several, and/or all of the above-discussed considerations, and/or additional/alternative external considerations may be balanced to optimize the compressor's performance. Although particular examples are provided, different compressor designs and applications may result in different values being selected.


According to various embodiments, the coolant injection timing, location, and/or direction, and/or other factors, and/or the higher efficiency of the compressor facilitates higher pressure ratios. As used herein, the pressure ratio is defined by a ratio of (1) the absolute inlet pressure of the source working fluid coming into the compression chamber (upstream pressure) to (2) the absolute outlet pressure of the compressed working fluid being expelled from the compression chamber (downstream pressure downstream from the outlet valve). As a result, the pressure ratio of the compressor is a function of the downstream vessel (pipeline, tank, etc.) into which the working fluid is being expelled. Compressors according to various embodiments of the present invention would have a 1:1 pressure ratio if the working fluid is being taken from and expelled into the ambient environment (e.g., 14.7 psia/14.7 psia). Similarly, the pressure ratio would be about 26:1 (385 psia/14.7 psia) according to various embodiments of the invention if the working fluid is taken from ambient (14.7 psia upstream pressure) and expelled into a vessel at 385 psia (downstream pressure).


According to various embodiments, the compressor has a pressure ratio of (1) at least 3:1, 4:1, 5:1, 6:1, 8:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, and/or 40:1 or higher, (2) less than or equal to 200:1, 150:1, 125:1, 100:1, 90:1, 80:1, 70:1, 60:1, 50:1, 45:1, 40:1, 35:1, and/or 30:1, and (3) any and all combinations of such upper and lower ratios (e.g., between 10:1 and 200:1, between 15:1 and 100:1, between 15:1 and 80:1, between 15:1 and 50:1, etc.).


According to various embodiments, lower pressure ratios (e.g., between 3:1 and 15:1) may be used for working fluids with higher liquid content (e.g., with a liquid volume fraction at the compressor's inlet port of at least 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, and/or 99%). Conversely, according to various embodiments, higher pressure ratios (e.g., above 15:1) may be used for working fluids with lower liquid content relative to gas content. However, wetter gases may nonetheless be compressed at higher pressure ratios and drier gases may be compressed at lower pressure ratios without deviating from the scope of the present invention.


Various embodiments of the invention are suitable for alternative operation using a variety of different operational parameters. For example, a single compressor according to one or more embodiments may be suitable to efficiently compress working fluids having drastically different liquid volume fractions and at different pressure ratios. For example, a compressor according to one or more embodiments is suitable for alternatively (1) compressing a working fluid with a liquid volume fraction of between 10 and 50 percent at a pressure ratio of between 3:1 and 15:1, and (2) compressing a working fluid with a liquid volume fraction of less than 10 percent at a pressure ratio of at least 15:1, 20:1, 30:1, and/or 40:1.


According to various embodiments, the compressor efficiently and cost-effectively compresses both wet and dry gas using a high pressure ratio.


According to various embodiments, the compressor is capable of and runs at commercially viable speeds (e.g., between 450 and 1800 rpm). According to various embodiments, the compressor runs at a speed of (a) at least 350, 400, 450, 500, 550, 600, and/or 650 rpm, (b) less than or equal to 3000, 2500, 2000, 1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, 1050, 1000, 950, 900, 850, and/or 800 rpm, and/or (c) between 350 and 300 rpm, 450-1800 rpm, and/or any ranges within these non-limiting upper and lower limits. According to various embodiments, the compressor is continuously operated at one or more of these speeds for at least 0.5, 1, 5, 10, 15, 20, 30, 60, 90, 100, 150, 200, 250 300, 350, 400, 450, and/or 500 minutes and/or at least 10, 20, 24, 48, 72, 100, 200, 300, 400, and/or 500 hours.


According to various embodiments, the outlet pressure of the compressed fluid is (1) at least 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 600, 700, 800, 900, 1000, 1250, 1500, 2000, 3000, 4000, and/or 5000 psig, (2) less than 6000, 5500, 5000, 4000, 3000, 2500, 2250, 2000, 1750, 1500, 1250, 1100, 1000, 900, 800, 700, 600 and/or 500 psig, (3) between 200 and 6000 psig, between 200 and 5000 psig, and/or (4) within any range between the upper and lower pressures described above.


According to various embodiments, the inlet pressure is ambient pressure in the environment surrounding the compressor (e.g., 1 atm, 14.7 psia). Alternatively, the inlet pressure could be close to a vacuum (near 0 psia), or anywhere therebetween. According to alternative embodiments, the inlet pressure may be (1) at least −14.5, −10, −5, 0, 5, 10, 25, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, and/or 1500 psig, (2) less than or equal to 3000, 2000, 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, 1000, 900, 800, 700, 600, 500, 400, and/or 350, and/or (3) between −14.5 and 3000 psig, between 0 and 1500 psig, and/or within any range bounded by any combination of the upper and lower numbers and/or any nested range within such ranges.


According to various embodiments, the outlet temperature of the working fluid when the working fluid is expelled from the compression chamber exceeds the inlet temperature of the working fluid when the working fluid enters the compression chamber by (a) less than 700, 650, 600, 550, 500, 450, 400, 375 350, 325, 300, 275, 250, 225, 200, 175, 150, 140, 130, 120, 110, 100, 90, 80, 70, 60, 50, 40, 30, and/or 20 degrees C., (b) at least −10, 0, 10, and/or 20 degrees C., and/or (c) any combination of ranges between any two of these upper and lower numbers, including any range within such ranges.


According to various embodiments, the outlet temperature of the working fluid is (a) less than 700, 650, 600, 550, 500, 450, 400, 375, 350, 325, 300, 275, 250, 225, 200, 175, 150, 140, 130, 120, 110, 100, 90, 80, 70, 60, 50, 40, 30, and/or 20 degrees C., (b) at least −10, 0, 10, 20, 30, 40, and/or 50 degrees C., and/or (c) any combination of ranges between any two of these upper and lower numbers, including any range within such ranges.


The outlet temperature and/or temperature increase may be a function of the working fluid. For example, the outlet temperature and temperature increase may be lower for some working fluids (e.g., methane) than for other working fluids (e.g., air).


According to various embodiments, the temperature increase is correlated to the pressure ratio. According to various embodiments, the temperature increase is less than 200 degrees C. for a pressure ratio of 20:1 or less (or between 15:1 and 20:1), and the temperature increase is less than 300 degrees C. for a pressure ratio of between 20:1 and 30:1.


According to various embodiments, the pressure ratio is between 3:1 and 15:1 for a working fluid with an inlet liquid volume fraction of over 5%, and the pressure ratio is between 15:1 and 40:1 for a working fluid with an inlet liquid volume fraction of between 1 and 20%. According to various embodiments, the pressure ratio is above 15:1 while the outlet pressure is above 250 psig, while the temperature increase is less than 200 degrees C. According to various embodiments, the pressure ratio is above 25:1 while the outlet pressure is above 250 psig and the temperature increase is less than 300 degrees C. According to various embodiments, the pressure ratio is above 15:1 while the outlet pressure is above 250 psig and the compressor speed is over 450 rpm.


According to various embodiments, any combination of the different ranges of different parameters discussed herein (e.g., pressure ratio, inlet temperature, outlet temperature, temperature change, inlet pressure, outlet pressure, pressure change, compressor speed, coolant injection rate, etc.) may be combined according to various embodiments of the invention. According to one or more embodiments, the pressure ratio is anywhere between 3:1 and 200:1 while the operating compressor speed is anywhere between 350 and 3000 rpm while the outlet pressure is between 200 and 6000 psig while the inlet pressure is between 0 and 3000 psig while the outlet temperature is between −10 and 650 degrees C. while the outlet temperature exceeds the inlet temperature by between 0 and 650 degrees C. while the liquid volume fraction of the working fluid at the compressor inlet is between 1% and 50%.


According to one or more embodiments, air is compressed from ambient pressure (14.7 psia) to 385 psia, a pressure ratio of 26:1, at speeds of 700 rpm with outlet temperatures remaining below 100 degrees C. Similar compression in an adiabatic environment would reach temperatures of nearly 480 degrees C.


The operating speed of the illustrated compressor is stated in terms of rpm because the illustrated compressor is a rotary compressor. However, other types of compressors may be used in alternative embodiments of the invention. As those familiar in the art appreciate, the RPM term also applies to other types of compressors, including piston compressors whose strokes are linked to RPM via their crankshaft.


Numerous cooling liquids may be used. For example, water, triethylene glycol, and various types of oils and other hydrocarbons may be used. Ethylene glycol, propylene glycol, methanol or other alcohols in case phase change characteristics are desired may be used. Refrigerants such as ammonia and others may also be used. Further, various additives may be combined with the cooling liquid to achieve desired characteristics. Along with the heat transfer and heat absorption properties of the liquid helping to cool the compression process, vaporization of the liquid may also be utilized in some embodiments of the design to take advantage of the large cooling effect due to phase change.


The effect of liquid coalescence is also addressed in the preferred embodiments. Liquid accumulation can provide resistance against the compressing mechanism, eventually resulting in hydrolock in which all motion of the compressor is stopped, causing potentially irreparable harm. As is shown in the embodiments of FIGS. 8 and 17, the inlet 420 and outlet 430 are located at the bottom of the rotor casing 400 on opposite sides of the gate 600, thus providing an efficient location for both intake of fluid to be compressed and exhausting of compressed fluid and the injected liquid. A valve is not necessary at the inlet 420. The inclusion of a dwell seal allows the inlet 420 to be an open port, simplifying the system and reducing inefficiencies associated with inlet valves. However, if desirable, an inlet valve could also be incorporated. Additional features may be added at the inlet to induce turbulence to provide enhanced thermal transfer and other benefits. Hardened materials may be used at the inlet and other locations of the compressor to protect against cavitation when liquid/gas mixtures enter into choke and other cavitation-inducing conditions.


Alternative embodiments may include an inlet located at positions other than shown in the figures. Additionally, multiple inlets may be located along the periphery of the cylinder. These could be utilized in isolation or combination to accommodate inlet streams of varying pressures and flow rates. The inlet ports can also be enlarged or moved, either automatically or manually, to vary the displacement of the compressor.


In these embodiments, multi-phase compression is utilized, thus the outlet system allows for the passage of both gas and liquid. Placement of outlet 430 near the bottom of the rotor casing 400 provides for a drain for the liquid. This minimizes the risk of hydrolock found in other liquid injection compressors. A small clearance volume allows any liquids that remain within the chamber to be accommodated. Gravity assists in collecting and eliminating the excess liquid, preventing liquid accumulation over subsequent cycles. Additionally, the sweeping motion of the rotor helps to ensure that most liquid is removed from the compressor during each compression cycle by guiding the liquid toward the outlet(s) and out of the compression chamber.


Compressed gas and liquid can be separated downstream from the compressor. As discussed below, liquid coolant can then be cooled and recirculated through the compressor.


Various of these features enable compressors according to various embodiments to effectively compress multi-phase fluids (e.g., a fluid that includes gas and liquid components (sometimes referred to as “wet gas”)) without pre-compression separation of the gas and liquid phase components of the working fluid. As used herein, multi-phase fluids have liquid volume fractions at the compressor inlet port of (a) at least 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, and/or 99.5%, (b) less than or equal to 99.5, 99, 98, 97, 96, 95, 94, 93, 92, 91, 90, 85, 80, 75, 70, 60, 50, 40, 35, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, and/or 0.5%, (c) between 0.5 and 99.5%, and/or (d) within any range bounded by these upper and lower values.


Outlet valves allow gas and liquid (i.e., from the wet gas and/or liquid coolant) to flow out of the compressor once the desired pressure within the compression chamber is reached. The outlet valves may increase or maximize the effective orifice area. Due to the presence of liquid in the working fluid, valves that minimize or eliminate changes in direction for the outflowing working fluid are desirable, but not required. This prevents the hammering effect of liquids as they change direction. Additionally, it is desirable to minimize clearance volume. Unused valve openings may be plugged in some applications to further minimize clearance volume. According to various embodiments, these features improve the wet gas capabilities of the compressor as well as the compressor's ability to utilize in-chamber liquid coolant.


Reed valves may be desirable as outlet valves. As one of ordinary skill in the art would appreciate, other types of valves known or as yet unknown may be utilized. Hoerbiger type R, CO, and Reed valves may be acceptable. Additionally, CT, HDS, CE, CM or Poppet valves may be considered. Other embodiments may use valves in other locations in the casing that allow gas to exit once the gas has reached a given pressure. In such embodiments, various styles of valves may be used. Passive or directly-actuated valves may be used and valve controllers may also be implemented.


In the presently preferred embodiments, the outlet valves are located near the bottom of the casing and serve to allow exhausting of liquid and compressed gas from the high pressure portion. In other embodiments, it may be useful to provide additional outlet valves located along periphery of main casing in locations other than near the bottom. Some embodiments may also benefit from outlets placed on the endplates. In still other embodiments, it may be desirable to separate the outlet valves into two types of valves—one predominately for high pressured gas, the other for liquid drainage. In these embodiments, the two or more types of valves may be located near each other, or in different locations.


The coolant liquid can be removed from the gas stream, cooled, and recirculated back into the compressor in a closed loop system. By placing the injector nozzles at locations in the compression chamber that do not see the full pressure of the system, the recirculation system may omit an additional pump (and subsequent efficiency loss) to deliver the atomized droplets. However, according to alternative embodiments, a pump is utilized to recirculate the liquid back into the compression chamber via the injector nozzles. Moreover, the injector nozzles may be disposed at locations in the compression chamber that see the full pressure of the system without deviating from the scope of the present invention.


One or more embodiments simplify heat recovery because most or all of the heat load is in the cooling liquid. According to various embodiments, heat is not removed from the compressed gas downstream of the compressor. The cooling liquid may cooled via an active cooling process (e.g., refrigeration and heat exchangers) downstream from the compressor. However, according to various embodiments, heat may additionally be recovered from the compressed gas (e.g., via heat exchangers) without deviating from the scope of the present invention.


As shown in FIGS. 8 and 17, the sealing portion 510 of the rotor effectively precludes fluid communication between the outlet and inlet ports by way of the creation of a dwell seal. The interface between the rotor 500 and gate 600 further precludes fluid communication between the outlet and inlet ports through use of a non-contacting seal or tip seal 620. In this way, the compressor is able to prevent any return and venting of fluid even when running at low speeds. Existing rotary compressors, when running at low speeds, have a leakage path from the outlet to the inlet and thus depend on the speed of rotation to minimize venting/leakage losses through this flowpath.


The high pressure working fluid exerts a large horizontal force on the gate 600. Despite the rigidity of the gate struts 210, this force will cause the gate 600 to bend and press against the inlet side of the gate casing 152. Specialized coatings that are very hard and have low coefficients of friction can coat both surfaces to minimize friction and wear from the sliding of the gate 600 against the gate casing 152. A fluid bearing can also be utilized. Alternatively, pegs (not shown) can extend from the side of the gate 600 into gate casing 150 to help support the gate 600 against this horizontal force. Material may also be removed from the non-pressure side of gate 600 in a non-symmetrical manner to allow more space for the gate 600 to bend before interfering with the gate casing 150.


The large horizontal forces encountered by the gate may also require additional considerations to reduce sliding friction of the gate's reciprocating motion. Various types of lubricants, such as greases or oils may be used. These lubricants may further be pressurized to help resist the force pressing the gate against the gate casing. Components may also provide a passive source of lubrication for sliding parts via lubricant-impregnated or self-lubricating materials. In the absence of, or in conjunction with, lubrication, replaceable wear elements may be used on sliding parts to ensure reliable operation contingent on adherence to maintenance schedules. These wear elements may also be used to precisely position the gate within the gate casing. As one of ordinary skill in the art would appreciate, replaceable wear elements may also be utilized on various other wear surfaces within the compressor.


The compressor structure may be comprised of materials such as aluminum, carbon steel, stainless steel, titanium, tungsten, or brass. Materials may be chosen based on corrosion resistance, strength, density, and cost. Seals may be comprised of polymers, such as PTFE, HDPE, PEEK™, acetal copolymer, etc., graphite, cast iron, carbon steel, stainless steel, or ceramics. Other materials known or unknown may be utilized. Coatings may also be used to enhance material properties.


As one of ordinary skill in the art can appreciate, various techniques may be utilized to manufacture and assemble the invention that may affect specific features of the design. For example, the main casing 110 may be manufactured using a casting process. In this scenario, the nozzle housings 132, gate casing 150, or other components may be formed in singularity with the main casing 110. Similarly, the rotor 500 and drive shaft 140 may be built as a single piece, either due to strength requirements or chosen manufacturing technique.


Further benefits may be achieved by utilizing elements exterior to the compressor envelope. A flywheel may be added to the drive shaft 140 to smooth the torque curve encountered during the rotation. A flywheel or other exterior shaft attachment may also be used to help achieve balanced rotation. Applications requiring multiple compressors may combine multiple compressors on a single drive shaft with rotors mounted out of phase to also achieve a smoothened torque curve. A bell housing or other shaft coupling may be used to attach the drive shaft to a driving force such as engine or electric motor to minimize effects of misalignment and increase torque transfer efficiency. Accessory components such as pumps or generators may be driven by the drive shaft using belts, direct couplings, gears, or other transmission mechanisms. Timing gears or belts may further be utilized to synchronize accessory components where appropriate.


After exiting the valves the mix of liquid and gases may be separated through any of the following methods or a combination thereof: 1. Interception through the use of a mesh, vanes, intertwined fibers; 2. Inertial impaction against a surface; 3. Coalescence against other larger injected droplets; 4. Passing through a liquid curtain; 5. Bubbling through a liquid reservoir; 6. Brownian motion to aid in coalescence; 7. Change in direction; 8. Centrifugal motion for coalescence into walls and other structures; 9. Inertia change by rapid deceleration; and 10. Dehydration through the use of adsorbents or absorbents.


At the outlet of the compressor, a pulsation chamber may consist of cylindrical bottles or other cavities and elements, may be combined with any of the aforementioned separation methods to achieve pulsation dampening and attenuation as well as primary or final liquid coalescence. Other methods of separating the liquid and gases may be used as well.


The presently preferred embodiments could be modified to operate as an expander. Further, although descriptions have been used to describe the top and bottom and other directions, the orientation of the elements (e.g. the gate 600 at the bottom of the rotor casing 400) should not be interpreted as limitations on the present invention.


While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention.


It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention. To the extent that “at least one” is used to highlight the possibility of a plurality of elements that may satisfy a claim element, this should not be interpreted as requiring “a” to mean singular only. “A” or “an” element may still be satisfied by a plurality of elements unless otherwise stated.

Claims
  • 1. A method of operating a compressor having a casing defining a compression chamber, an inlet port into the compression chamber, and a rotatable drive shaft configured to drive the compressor, the method comprising: moving a working fluid into the compression chamber through the inlet port, wherein the working fluid is a multi-phase fluid that includes gas and liquid components and has a liquid volume fraction at the inlet port of at least 0.5%; andcompressing the working fluid using the compressor such that a single stage pressure ratio of the compressor is at least 3:1.
  • 2. The method of claim 1, wherein the compressor comprises a positive displacement rotary compressor that includes a rotor connected to the drive shaft for rotation with the drive shaft relative to the casing.
  • 3. The method of claim 2, wherein: the method further comprises, after said compressing, expelling compressed working fluid out of the compression chamber through an outlet port in the compression chamber; andthe pressure ratio comprises a ratio of (a) an absolute inlet pressure of the working fluid at the inlet port, to (b) an absolute outlet pressure of the working fluid expelled from the compression chamber through the outlet port.
  • 4. The method of claim 3, wherein an outlet temperature of the compressed working fluid being expelled through the outlet port is less than 250 degrees C.
  • 5. The method of claim 3, wherein an outlet temperature of the compressed working fluid being expelled through the outlet port exceeds an inlet temperature of the working fluid entering the compression chamber through the inlet port by less than 250 degrees C.
  • 6. The method of claim 2, wherein said pressure ratio is between 5:1 and 100:1.
  • 7. The method of claim 6, wherein said pressure ratio is at least 10:1.
  • 8. The method of claim 6, wherein said pressure ratio is at least 15:1.
  • 9. The method of claim 2, wherein the compressed fluid is expelled from the compressor at an outlet pressure of between 275 and 6000 psig.
  • 10. The method of claim 9, wherein the outlet pressure is at least 325 psig.
  • 11. The method of claim 2, wherein a rotational axis of the rotor is oriented in a horizontal direction during said compressing.
  • 12. The method of claim 2, further comprising injecting liquid coolant into the compression chamber during said compressing, wherein said injecting comprises injecting atomized liquid coolant with an average droplet size of 300 microns or less into a compression volume defined between the rotor and an inner wall of the compression chamber.
  • 13. The method of claim 2, wherein: the compression chamber is defined by a cylindrical inner wall of the casing;the compression chamber includes an outlet port;the rotor has a sealing portion that corresponds to a curvature of the inner wall of the casing and has a constant radius, anda non-sealing portion having a variable radius;the rotor rotates concentrically relative to the cylindrical inner wall during the compressing;the compressor comprises at least one liquid injector connected with the casing, the at least one liquid injector carrying out said injecting;the compressor comprises a gate having a first end and a second end, and operable to move within the casing to locate the first end proximate to the rotor as the rotor rotates during the compressing;the gate separates an inlet volume and a compression volume in the compression chamber;the inlet port is configured to enable suction in of the working fluid; andthe outlet port is configured to enable expulsion of both liquid and gas.
  • 14. The method of claim 2, wherein: the compression chamber has a cylindrical inner wall; andthe rotor has a sealing portion that corresponds to a curvature of the inner wall and has a constant radius, anda non-sealing portion having a variable radius.
  • 15. The method of claim 1, wherein the liquid volume fraction at the inlet port is at least 1%.
  • 16. The method of claim 1, wherein the liquid volume fraction at the inlet port is at least 5%.
  • 17. A compressor comprising: a casing with an inner wall defining a compression chamber and an inlet port into the compression chamber;a positive displacement compressing structure movable relative to the casing to compress a working fluid that moves into the compression chamber via the inlet port; anda rotatable drive shaft configured to drive the compressing structure,wherein a single stage pressure ratio of the compressor is at least 3:1, andthe compressor is shaped and configured for the working fluid to be a multi-phase fluid that includes gas and liquid components and has a liquid volume fraction at the inlet port of at least 0.5%.
  • 18. The compressor of claim 17, wherein: the compressor comprises a positive displacement rotary compressor; andthe compressing structure comprises a rotor connected to the drive shaft for rotation with the drive shaft relative to the casing.
  • 19. The compressor of claim 18, wherein said pressure ratio is between 5:1 and 100:1.
  • 20. The compressor of claim 19, wherein said pressure ratio is at least 10:1.
  • 21. The compressor of claim 19, wherein said pressure ratio is at least 15:1.
  • 22. The compressor of claim 18, wherein the compressor is shaped and configured for the working fluid to be the multi-phase fluid that has the liquid volume fraction at the inlet port of at least 1%.
  • 23. The compressor of claim 18, wherein the compressor is shaped and configured such that during operation, the compressed working fluid is expelled from the compressor at an outlet pressure of between 275 and 6000 psig.
  • 24. The compressor of claim 23, wherein the outlet pressure is at least 325 psig.
  • 25. The compressor of claim 18, wherein: the compression chamber includes an outlet port;the inner wall is cylindrical;the rotor has a sealing portion that corresponds to a curvature of the inner wall and has a constant radius, anda non-sealing portion having a variable radius;the rotor is connected to the casing for concentric rotation within the compression chamber;the compressor comprises a gate having a first end and a second end, and operable to move within the casing to locate the first end proximate to the rotor as the rotor rotates;the gate separates an inlet volume and a compression volume in the compression chamber;the inlet port is configured to enable suction in of the working fluid; andthe outlet is configured to enable expulsion of both liquid and gas.
  • 26. The compressor of claim 18, wherein: the compression chamber has a cylindrical inner wall; andthe rotor has a sealing portion that corresponds to a curvature of the inner wall and has a constant radius, anda non-sealing portion having a variable radius.
  • 27. The compressor of claim 17, further comprising at least one liquid injector connected to the casing and configured to inject liquid coolant into the compression chamber during compression of the working fluid.
CROSS REFERENCE

This application is a divisional of U.S. Ser. No. 13,782,845, titled “Compressor With Liquid Injection Cooling,” filed Mar. 1, 2013, which is a continuation-in-part of U.S. Ser. No. 13/220,528, titled “Compressor With Liquid Injection Cooling,” filed Aug. 29, 2011, which claims priority to U.S. provisional application Ser. No. 61/378,297, which was filed on Aug. 30, 2010, and U.S. provisional application Ser. No. 61/485,006, which was filed on May 11, 2011, all of which are incorporated by reference herein in their entirety. U.S. Ser. No. 13,782,845 is also a continuation in part of PCT Application No. PCT/US2011/49599, titled “Compressor With Liquid Injection Cooling,” filed Aug. 29, 2011, the entire contents of which are incorporated herein by reference in its entirety. U.S. Ser. No. 13,782,845, also claims priority to U.S. Provisional Application No. 61/770,989, titled “Compressor With Liquid Injection Cooling,” filed Feb. 28, 2013, the entire contents of which are incorporated herein by reference in its entirety. This application claims priority to all of these applications.

US Referenced Citations (886)
Number Name Date Kind
2324434 Shore Jul 1943 A
2800274 Makaroff et al. Jul 1957 A
3795117 Moody, Jr. et al. Mar 1974 A
3820350 Brandin et al. Jun 1974 A
3820923 Zweifel Jun 1974 A
3850554 Zimmern Nov 1974 A
3934967 Gannaway Jan 1976 A
3936239 Shaw Feb 1976 A
3936249 Sato Feb 1976 A
3939907 Skvarenina Feb 1976 A
3941521 Weatherston Mar 1976 A
3941522 Acord Mar 1976 A
3945220 Kosfeld Mar 1976 A
3945464 Sato Mar 1976 A
3947551 Parrish Mar 1976 A
3954088 Scott May 1976 A
3976404 Dennison Aug 1976 A
3981627 Kantor Sep 1976 A
3981703 Glanvall et al. Sep 1976 A
3988080 Takada Oct 1976 A
3988081 Goloff et al. Oct 1976 A
3994638 Garland et al. Nov 1976 A
3995431 Schwartzman Dec 1976 A
3998243 Osterkorn et al. Dec 1976 A
4005949 Grant Feb 1977 A
4012180 Berkowitz et al. Mar 1977 A
4012183 Calabretta Mar 1977 A
4018548 Berkowitz Apr 1977 A
4021166 Glanvall et al. May 1977 A
4022553 Poole et al. May 1977 A
4025244 Sato May 1977 A
4028016 Keijer Jun 1977 A
4028021 Berkowitz Jun 1977 A
4032269 Sheth Jun 1977 A
4032270 Sheth et al. Jun 1977 A
4033708 Weatherston Jul 1977 A
4035114 Sato Jul 1977 A
RE29378 Bloom Aug 1977 E
4048867 Saari Sep 1977 A
4050855 Sakamaki et al. Sep 1977 A
4057367 Moe et al. Nov 1977 A
4058361 Giurlando et al. Nov 1977 A
4058988 Shaw Nov 1977 A
4060342 Riffe et al. Nov 1977 A
4060343 Newton Nov 1977 A
4061446 Sakamaki et al. Dec 1977 A
4068981 Mandy Jan 1978 A
4071306 Calabretta Jan 1978 A
4072452 Sheth Feb 1978 A
4076259 Raimondi Feb 1978 A
4076469 Weatherston Feb 1978 A
4086040 Shibuya et al. Apr 1978 A
4086041 Takada Apr 1978 A
4086042 Young Apr 1978 A
RE29627 Weatherston May 1978 E
4086880 Bates May 1978 A
4099405 Hauk et al. Jul 1978 A
4099896 Glanvall Jul 1978 A
4104010 Shibuya Aug 1978 A
4105375 Schindelhauer Aug 1978 A
4112881 Townsend Sep 1978 A
4118157 Mayer Oct 1978 A
4118158 Osaki Oct 1978 A
4127369 Eiermann et al. Nov 1978 A
4132512 Roberts Jan 1979 A
4135864 Lassota Jan 1979 A
4135865 Takata Jan 1979 A
4137018 Brucken Jan 1979 A
4137021 Lassota Jan 1979 A
4137022 Lassota Jan 1979 A
4144002 Shibuya et al. Mar 1979 A
4144005 Bracken Mar 1979 A
4150926 Eiermann Apr 1979 A
4152100 Poole et al. May 1979 A
4174195 Lassota Nov 1979 A
4174931 Ishizuka Nov 1979 A
4179250 Patel Dec 1979 A
4181474 Shaw Jan 1980 A
4182441 Strong et al. Jan 1980 A
4196594 Abom Apr 1980 A
4198195 Sakamaki et al. Apr 1980 A
4206930 Thrane et al. Jun 1980 A
4209287 Takada Jun 1980 A
4218199 Eiermann Aug 1980 A
4219314 Haggerty Aug 1980 A
4222715 Ruf Sep 1980 A
4224014 Glanvall Sep 1980 A
4227755 Lundberg Oct 1980 A
4235217 Cox Nov 1980 A
4236875 Widdowson Dec 1980 A
4239467 Glanvall Dec 1980 A
4242878 Brinkerhoff Jan 1981 A
4244680 Ishizuka et al. Jan 1981 A
4248575 Watanabe et al. Feb 1981 A
4249384 Harris Feb 1981 A
4251190 Brown et al. Feb 1981 A
4252511 Bowdish Feb 1981 A
4253805 Steinwart et al. Mar 1981 A
4255100 Linder Mar 1981 A
4274816 Kobayashi et al. Jun 1981 A
4275310 Summers et al. Jun 1981 A
4279578 Kim et al. Jul 1981 A
4295806 Tanaka et al. Oct 1981 A
4299547 Simon Nov 1981 A
4302343 Carswell et al. Nov 1981 A
4306845 Gunderson Dec 1981 A
4311025 Rice Jan 1982 A
4312181 Clark Jan 1982 A
4330240 Eslinger May 1982 A
4331002 Ladusaw May 1982 A
4332534 Becker Jun 1982 A
4336686 Porter Jun 1982 A
RE30994 Shaw Jul 1982 E
4340578 Erickson Jul 1982 A
4342547 Yamada et al. Aug 1982 A
4345886 Nakayama et al. Aug 1982 A
4355963 Tanaka et al. Oct 1982 A
4362472 Axelsson Dec 1982 A
4362473 Zeilon Dec 1982 A
4367625 Vitale Jan 1983 A
4371311 Walsh Feb 1983 A
4373356 Connor Feb 1983 A
4373880 Tanaka et al. Feb 1983 A
4373881 Matsushita Feb 1983 A
4383804 Budzich May 1983 A
4385498 Fawcett et al. May 1983 A
4385875 Kanazawa May 1983 A
4388048 Shaw et al. Jun 1983 A
4389172 Griffith Jun 1983 A
4390322 Budzich Jun 1983 A
4391573 Tanaka et al. Jul 1983 A
4395208 Maruyama et al. Jul 1983 A
4396361 Fraser, Jr. Aug 1983 A
4396365 Hayashi Aug 1983 A
4397618 Stenzel Aug 1983 A
4397620 Inagaki et al. Aug 1983 A
4402653 Maruyama et al. Sep 1983 A
4403929 Nagasaku et al. Sep 1983 A
4408968 Inagaki et al. Oct 1983 A
4415320 Maruyama et al. Nov 1983 A
4419059 Anderson Dec 1983 A
4419865 Szymaszek Dec 1983 A
4423710 Williams Jan 1984 A
4427351 Sano Jan 1984 A
4431356 Lassota Feb 1984 A
4431387 Lassota Feb 1984 A
4437818 Weatherston Mar 1984 A
4439121 Shaw Mar 1984 A
4441863 Hotta et al. Apr 1984 A
4445344 Ladusaw May 1984 A
4447196 Nagasaku et al. May 1984 A
4451220 Ito et al. May 1984 A
4452570 Fujisaki et al. Jun 1984 A
4452571 Koda et al. Jun 1984 A
4455825 Pinto Jun 1984 A
4457671 Watanabe Jul 1984 A
4457680 Paget Jul 1984 A
4459090 Maruyama et al. Jul 1984 A
4459817 Inagaki et al. Jul 1984 A
4460309 Walsh Jul 1984 A
4460319 Ashikian Jul 1984 A
4464102 Eiermann Aug 1984 A
4470375 Showalter Sep 1984 A
4472119 Roberts Sep 1984 A
4472121 Tanaka et al. Sep 1984 A
4472122 Yoshida et al. Sep 1984 A
4477233 Schaefer Oct 1984 A
4478054 Shaw et al. Oct 1984 A
4478553 Leibowitz et al. Oct 1984 A
4479763 Sakamaki et al. Oct 1984 A
4484873 Inagaki et al. Nov 1984 A
4486158 Maruyama et al. Dec 1984 A
4487029 Hidaka et al. Dec 1984 A
4487561 Eiermann Dec 1984 A
4487562 Inagaki et al. Dec 1984 A
4487563 Mori et al. Dec 1984 A
4490100 Okazaki Dec 1984 A
4494386 Edwards et al. Jan 1985 A
4497185 Shaw Feb 1985 A
4502284 Chrisoghilos Mar 1985 A
4502850 Inagaki et al. Mar 1985 A
4505653 Roberts Mar 1985 A
4507064 Kocher et al. Mar 1985 A
4508491 Schaefer Apr 1985 A
4508495 Monden et al. Apr 1985 A
4509906 Hattori et al. Apr 1985 A
4512728 Nakano et al. Apr 1985 A
4514156 Sakamaki et al. Apr 1985 A
4514157 Nakamura et al. Apr 1985 A
4515513 Hayase et al. May 1985 A
4516914 Murphy et al. May 1985 A
4518330 Asami et al. May 1985 A
4519748 Murphy et al. May 1985 A
4521167 Cavalleri et al. Jun 1985 A
4524599 Bailey Jun 1985 A
4531899 Sudbeck et al. Jul 1985 A
4536130 Orlando et al. Aug 1985 A
4536141 Maruyama Aug 1985 A
4537567 Kawaguchi et al. Aug 1985 A
4543046 Hasegawa Sep 1985 A
4543047 Hasegawa Sep 1985 A
4544337 Maruyama Oct 1985 A
4544338 Takebayashi et al. Oct 1985 A
4545742 Schaefer Oct 1985 A
4548549 Murphy et al. Oct 1985 A
4548558 Sakamaki et al. Oct 1985 A
4553903 Ashikian Nov 1985 A
4553912 Lassota Nov 1985 A
4557677 Hasegawa Dec 1985 A
4558993 Hori et al. Dec 1985 A
4560329 Hirahara et al. Dec 1985 A
4560332 Yokoyama et al. Dec 1985 A
4561829 Iwata et al. Dec 1985 A
4561835 Sakamaki et al. Dec 1985 A
4564344 Sakamaki et al. Jan 1986 A
4565181 August Jan 1986 A
4565498 Schmid et al. Jan 1986 A
4566863 Goto et al. Jan 1986 A
4566869 Pandeya et al. Jan 1986 A
4569645 Asami et al. Feb 1986 A
4573879 Uetuji et al. Mar 1986 A
4573891 Sakunaki et al. Mar 1986 A
4577472 Pandeya et al. Mar 1986 A
4580949 Maruyama et al. Apr 1986 A
4580950 Sumikawa et al. Apr 1986 A
4592705 Ueda et al. Jun 1986 A
4594061 Terauchi Jun 1986 A
4594062 Sakamaki et al. Jun 1986 A
4595347 Sakamaki et al. Jun 1986 A
4595348 Sakamaki et al. Jun 1986 A
4598559 Tomayko et al. Jul 1986 A
4599059 Hsu Jul 1986 A
4601643 Seidel Jul 1986 A
4601644 Gannaway Jul 1986 A
4605362 Sturgeon et al. Aug 1986 A
4608002 Hayase et al. Aug 1986 A
4609329 Pillis et al. Sep 1986 A
4610602 Schmid et al. Sep 1986 A
4610612 Kocher Sep 1986 A
4610613 Szymaszek Sep 1986 A
4614484 Riegler Sep 1986 A
4616984 Inagaki et al. Oct 1986 A
4618317 Matsuzaki Oct 1986 A
4619112 Colgate Oct 1986 A
4620837 Sakamaki et al. Nov 1986 A
4621986 Sudo Nov 1986 A
4623304 Chikada et al. Nov 1986 A
4624630 Hirahara et al. Nov 1986 A
4626180 Tagawa et al. Dec 1986 A
4627802 Draaisma et al. Dec 1986 A
4629403 Wood Dec 1986 A
4631011 Whitfield Dec 1986 A
4636152 Kawaguchi et al. Jan 1987 A
4636153 Ishizuka et al. Jan 1987 A
4636154 Sugiyama et al. Jan 1987 A
4639198 Gannaway Jan 1987 A
4640669 Gannaway Feb 1987 A
4645429 Asami et al. Feb 1987 A
4646533 Morita et al. Mar 1987 A
4648815 Williams Mar 1987 A
4648818 Sakamaki et al. Mar 1987 A
4648819 Sakamaki et al. Mar 1987 A
4657493 Sakamaki et al. Apr 1987 A
4664608 Adams et al. May 1987 A
4674960 Rando et al. Jun 1987 A
4676067 Pinto Jun 1987 A
4676726 Kawaguchi et al. Jun 1987 A
4684330 Andersson et al. Aug 1987 A
4701110 Iijima Oct 1987 A
4704069 Kocher et al. Nov 1987 A
4704073 Nomura et al. Nov 1987 A
4704076 Kawaguchi et al. Nov 1987 A
4706353 Zgliczynski et al. Nov 1987 A
4708598 Sugita et al. Nov 1987 A
4708599 Suzuki Nov 1987 A
4710111 Kubo Dec 1987 A
4711617 Asami et al. Dec 1987 A
4712986 Nissen Dec 1987 A
4715435 Foret Dec 1987 A
4715800 Nishizawa et al. Dec 1987 A
4716347 Fujimoto Dec 1987 A
4717316 Muramatsu et al. Jan 1988 A
4720899 Ando et al. Jan 1988 A
D294361 Williams Feb 1988 S
4725210 Suzuki et al. Feb 1988 A
4726739 Saitou et al. Feb 1988 A
4726740 Suzuki et al. Feb 1988 A
4728273 Linder et al. Mar 1988 A
4730996 Akatsuchi et al. Mar 1988 A
4737088 Taniguchi et al. Apr 1988 A
4739632 Fry Apr 1988 A
4743183 Irie et al. May 1988 A
4743184 Sumikawa et al. May 1988 A
4746277 Glanvall May 1988 A
4747276 Kakinuma May 1988 A
4758138 Timuska Jul 1988 A
4759698 Nissen Jul 1988 A
4762471 Asanuma et al. Aug 1988 A
4764095 Fickelscher Aug 1988 A
4764097 Hirahara et al. Aug 1988 A
4776074 Suzuki et al. Oct 1988 A
4780067 Suzuki et al. Oct 1988 A
4781542 Ozu et al. Nov 1988 A
4781545 Yokomizo et al. Nov 1988 A
4781551 Tanaka Nov 1988 A
4782569 Wood Nov 1988 A
4785640 Naruse Nov 1988 A
4793779 Schabert et al. Dec 1988 A
4793791 Kokuryo Dec 1988 A
4794752 Redderson Jan 1989 A
4795325 Kishi et al. Jan 1989 A
4801251 Nakajima et al. Jan 1989 A
4815953 Iio Mar 1989 A
4819440 Nakajima et al. Apr 1989 A
4822263 Nakajima et al. Apr 1989 A
4826408 Inoue et al. May 1989 A
4826409 Kohayakawa et al. May 1989 A
4828463 Nishizawa et al. May 1989 A
4828466 Kim May 1989 A
4830590 Sumikawa et al. May 1989 A
4834627 Gannaway May 1989 A
4834634 Ono May 1989 A
4850830 Okoma et al. Jul 1989 A
4859154 Aihara et al. Aug 1989 A
4859162 Cox Aug 1989 A
4859164 Shimomura Aug 1989 A
4860704 Slaughter Aug 1989 A
4861372 Shimomura Aug 1989 A
4867658 Sugita et al. Sep 1989 A
4877380 Glanvall Oct 1989 A
4877384 Chu Oct 1989 A
4881879 Ortiz Nov 1989 A
4884956 Fujitani et al. Dec 1989 A
4889475 Gannaway et al. Dec 1989 A
4895501 Bagepalli Jan 1990 A
4902205 DaCosta et al. Feb 1990 A
4904302 Shimomura Feb 1990 A
4909716 Orosz et al. Mar 1990 A
4911624 Bagepalli Mar 1990 A
4915554 Serizawa et al. Apr 1990 A
4916914 Short Apr 1990 A
4925378 Ushiku et al. May 1990 A
4929159 Hayase et al. May 1990 A
4929161 Aoki et al. May 1990 A
4932844 Glanvall Jun 1990 A
4932851 Kim Jun 1990 A
4934454 Vandyke et al. Jun 1990 A
4934656 Groves et al. Jun 1990 A
4934912 Iio et al. Jun 1990 A
4941810 Iio et al. Jul 1990 A
4943216 Iio Jul 1990 A
4943217 Nuber Jul 1990 A
4944663 Iizuka et al. Jul 1990 A
4946362 Soderlund et al. Aug 1990 A
4955414 Fujii Sep 1990 A
4960371 Bassett Oct 1990 A
4968228 Da Costa et al. Nov 1990 A
4968231 Zimmern et al. Nov 1990 A
4969832 Fry Nov 1990 A
4971529 Gannaway et al. Nov 1990 A
4975031 Bagepalli et al. Dec 1990 A
4978279 Rodgers Dec 1990 A
4978287 Da Costa Dec 1990 A
4979879 Da Costa Dec 1990 A
4983108 Kawaguchi et al. Jan 1991 A
4990073 Kudo et al. Feb 1991 A
4993923 Daeyaert Feb 1991 A
4997352 Fujiwara et al. Mar 1991 A
5001924 Walter et al. Mar 1991 A
5004408 Da Costa Apr 1991 A
5004410 Da Costa Apr 1991 A
5006051 Hattori Apr 1991 A
5007331 Greiner et al. Apr 1991 A
5007813 Da Costa Apr 1991 A
5009577 Hayase et al. Apr 1991 A
5009583 Carlsson et al. Apr 1991 A
5012896 Da Costa May 1991 A
5015161 Amin et al. May 1991 A
5015164 Kudou et al. May 1991 A
5018948 Sjteöholm et al. May 1991 A
D317313 Yoshida et al. Jun 1991 S
5020975 Aihara Jun 1991 A
5022146 Gannaway et al. Jun 1991 A
5024588 Lassota Jun 1991 A
5026257 Aihara et al. Jun 1991 A
5027602 Glen et al. Jul 1991 A
5027606 Short Jul 1991 A
5030066 Aihara et al. Jul 1991 A
5030073 Serizawa et al. Jul 1991 A
5035584 Akaike et al. Jul 1991 A
5037282 Englund Aug 1991 A
5039287 Da Costa Aug 1991 A
5039289 Eiermann et al. Aug 1991 A
5039900 Nashiki et al. Aug 1991 A
5044908 Kawade Sep 1991 A
5044909 Lindstrom Sep 1991 A
5046932 Hoffmann Sep 1991 A
5049052 Aihara Sep 1991 A
5050233 Hitosugi et al. Sep 1991 A
5051076 Okoma et al. Sep 1991 A
5055015 Furukawa Oct 1991 A
5055016 Kawade Oct 1991 A
5062779 Da Costa Nov 1991 A
5063750 Englund Nov 1991 A
5067557 Nuber et al. Nov 1991 A
5067878 Da Costa Nov 1991 A
5067884 Lee Nov 1991 A
5069607 Da Costa Dec 1991 A
5074761 Hirooka et al. Dec 1991 A
5076768 Ruf et al. Dec 1991 A
5080562 Barrows et al. Jan 1992 A
5087170 Kousokabe et al. Feb 1992 A
5087172 Ferri et al. Feb 1992 A
5088892 Weingold et al. Feb 1992 A
5090879 Weinbrecht Feb 1992 A
5090882 Serizawa et al. Feb 1992 A
5092130 Nagao et al. Mar 1992 A
5098266 Takimoto et al. Mar 1992 A
5102317 Okoma et al. Apr 1992 A
5104297 Sekiguchi et al. Apr 1992 A
5108269 Glanvall Apr 1992 A
5109764 Kappel et al. May 1992 A
5116208 Parme May 1992 A
5120207 Soderlund Jun 1992 A
5125804 Akaike et al. Jun 1992 A
5131826 Boussicault Jul 1992 A
5133652 Abe et al. Jul 1992 A
5135368 Amin et al. Aug 1992 A
5135370 Iio Aug 1992 A
5139391 Carrouset Aug 1992 A
5144805 Nagao et al. Sep 1992 A
5144810 Nagao et al. Sep 1992 A
5151015 Bauer et al. Sep 1992 A
5151021 Fujiwara et al. Sep 1992 A
5152156 Tokairin Oct 1992 A
5154063 Nagao et al. Oct 1992 A
5169299 Gannaway Dec 1992 A
5178514 Damiral Jan 1993 A
5179839 Bland Jan 1993 A
5184944 Scarfone Feb 1993 A
5186956 Tanino et al. Feb 1993 A
5188524 Bassine Feb 1993 A
5203679 Yun et al. Apr 1993 A
5203686 Scheldorf et al. Apr 1993 A
5207568 Szymaszek May 1993 A
5217681 Wedellsborg et al. Jun 1993 A
5218762 Netto Da Costa Jun 1993 A
5221191 Leyderman et al. Jun 1993 A
5222879 Kapadia Jun 1993 A
5222884 Kapadia Jun 1993 A
5222885 Cooksey Jun 1993 A
5226797 Da Costa Jul 1993 A
5230616 Serizawa et al. Jul 1993 A
5232349 Kimura et al. Aug 1993 A
5233954 Chomyszak Aug 1993 A
5236318 Richardson, Jr. Aug 1993 A
5239833 Fineblum Aug 1993 A
5240386 Amin et al. Aug 1993 A
5242280 Fujio Sep 1993 A
5244366 Delmotte Sep 1993 A
5251456 Nagao et al. Oct 1993 A
5256042 McCullough et al. Oct 1993 A
5259740 Youn Nov 1993 A
5264820 Kovacich et al. Nov 1993 A
5267839 Kimura et al. Dec 1993 A
5273412 Zwaans Dec 1993 A
5284426 Strikis et al. Feb 1994 A
5293749 Nagao et al. Mar 1994 A
5293752 Nagao et al. Mar 1994 A
5302095 Richardson, Jr. Apr 1994 A
5302096 Cavalleri Apr 1994 A
5304033 Tang Apr 1994 A
5304043 Shilling Apr 1994 A
5306128 Lee Apr 1994 A
5308125 Anderson, Jr. May 1994 A
5310326 Gui et al. May 1994 A
5311739 Clark May 1994 A
5314318 Hata et al. May 1994 A
5316455 Yoshimura et al. May 1994 A
5322420 Yannascoli Jun 1994 A
5322424 Fujio Jun 1994 A
5322427 Hsin-Tau Jun 1994 A
5328344 Sato et al. Jul 1994 A
5334004 Lefevre et al. Aug 1994 A
5336059 Rowley Aug 1994 A
5337572 Longsworth Aug 1994 A
5346376 Bookbinder et al. Sep 1994 A
5348455 Herrick et al. Sep 1994 A
5352098 Hood Oct 1994 A
5365743 Nagao et al. Nov 1994 A
5366703 Liechti et al. Nov 1994 A
5368456 Hirayama et al. Nov 1994 A
5370506 Fujii et al. Dec 1994 A
5370511 Strikis et al. Dec 1994 A
5372483 Kimura et al. Dec 1994 A
5374171 Cooksey Dec 1994 A
5374172 Edwards Dec 1994 A
5380165 Kimura et al. Jan 1995 A
5380168 Kimura et al. Jan 1995 A
5383773 Richardson, Jr. Jan 1995 A
5383774 Toyama et al. Jan 1995 A
5385450 Kimura et al. Jan 1995 A
5385451 Fujii et al. Jan 1995 A
5385458 Chu Jan 1995 A
5393205 Fujii et al. Feb 1995 A
5394709 Lorentzen Mar 1995 A
5395326 Haber et al. Mar 1995 A
5397215 Spear et al. Mar 1995 A
5397218 Fujii et al. Mar 1995 A
5399076 Matsuda et al. Mar 1995 A
5411385 Eto et al. May 1995 A
5411387 Lundin et al. May 1995 A
5419685 Fujii et al. May 1995 A
5427068 Palmer Jun 1995 A
5427506 Fry et al. Jun 1995 A
5433179 Wittry Jul 1995 A
5437251 Anglim et al. Aug 1995 A
5439358 Weinbrecht Aug 1995 A
5442923 Bareiss Aug 1995 A
5443376 Choi Aug 1995 A
5447033 Nagao et al. Sep 1995 A
5447422 Aoki et al. Sep 1995 A
5472327 Strikis et al. Dec 1995 A
5477688 Ban et al. Dec 1995 A
5479887 Chen Jan 1996 A
5489199 Palmer Feb 1996 A
5490771 Wehber et al. Feb 1996 A
5494412 Shin Feb 1996 A
5494423 Ishiyama et al. Feb 1996 A
5499515 Kawamura et al. Mar 1996 A
5501579 Kimura et al. Mar 1996 A
5503539 Nakajima et al. Apr 1996 A
5503540 Kim Apr 1996 A
5511389 Bush et al. Apr 1996 A
5518381 Matsunaga et al. May 1996 A
5522235 Matsuoka et al. Jun 1996 A
5522356 Palmer Jun 1996 A
5529469 Bushnell et al. Jun 1996 A
5536149 Fujii et al. Jul 1996 A
5542831 Scarfone Aug 1996 A
5542832 Sone et al. Aug 1996 A
5544400 Wells Aug 1996 A
5545021 Fukuoka et al. Aug 1996 A
5556270 Komine et al. Sep 1996 A
5564280 Schilling et al. Oct 1996 A
5564910 Huh Oct 1996 A
5564916 Yamamoto et al. Oct 1996 A
5564917 Leyderman et al. Oct 1996 A
5568796 Palmer Oct 1996 A
5577903 Yamamoto Nov 1996 A
5580231 Yasui Dec 1996 A
5582020 Scaringe et al. Dec 1996 A
5586443 Lewis Dec 1996 A
5586876 Yasnnascoli et al. Dec 1996 A
5591018 Takeuchi et al. Jan 1997 A
5591023 Nakamura et al. Jan 1997 A
5597287 Helmick Jan 1997 A
5605447 Kim et al. Feb 1997 A
5616017 Iizuka et al. Apr 1997 A
5616018 Ma Apr 1997 A
5616019 Hattori et al. Apr 1997 A
5622149 Wittry Apr 1997 A
5626463 Kimura et al. May 1997 A
5639208 Theis Jun 1997 A
5640938 Craze Jun 1997 A
5641273 Moseley Jun 1997 A
5641280 Timuska Jun 1997 A
5653585 Fresco Aug 1997 A
5660540 Kang Aug 1997 A
5662463 Mirzoev et al. Sep 1997 A
5664941 Bearint Sep 1997 A
5667372 Hwang et al. Sep 1997 A
5672054 Cooper et al. Sep 1997 A
5674053 Paul et al. Oct 1997 A
5674061 Motegi et al. Oct 1997 A
5676535 Bushnell Oct 1997 A
5678164 Berthelemy et al. Oct 1997 A
5678987 Timuska Oct 1997 A
5685703 Fukuoka et al. Nov 1997 A
5690475 Yamada et al. Nov 1997 A
5692887 Krueger et al. Dec 1997 A
5697763 Kitchener Dec 1997 A
5699672 Foerster et al. Dec 1997 A
5707223 Englund et al. Jan 1998 A
5713732 Riney Feb 1998 A
5727936 Eriksson et al. Mar 1998 A
5733112 Kang Mar 1998 A
5738497 Hensley Apr 1998 A
5758613 Edelmayer et al. Jun 1998 A
5769610 Paul et al. Jun 1998 A
5775882 Kiyokawa et al. Jul 1998 A
5775883 Hattori et al. Jul 1998 A
5782618 Nishikawa et al. Jul 1998 A
5788472 Lee Aug 1998 A
5795136 Olsaker et al. Aug 1998 A
5800142 Motegi et al. Sep 1998 A
5820349 Caillat Oct 1998 A
5820357 Itoh Oct 1998 A
5823755 Wilson et al. Oct 1998 A
5829960 Dreiman Nov 1998 A
5839270 Jirnov et al. Nov 1998 A
5853288 Motegi et al. Dec 1998 A
5860801 Timuska Jan 1999 A
5863191 Motegi et al. Jan 1999 A
5873261 Bac Feb 1999 A
5875744 Vallejos Mar 1999 A
5921106 Girault et al. Jul 1999 A
5947710 Cooper et al. Sep 1999 A
5947711 Myers et al. Sep 1999 A
5950452 Sakitani et al. Sep 1999 A
5951269 Sasa et al. Sep 1999 A
5951273 Matsunaga et al. Sep 1999 A
5957676 Peeters Sep 1999 A
5961297 Haga et al. Oct 1999 A
5980222 Fry Nov 1999 A
6017186 Hoeger et al. Jan 2000 A
6017203 Sugawa et al. Jan 2000 A
6027322 Ferentinos et al. Feb 2000 A
6032720 Riegger et al. Mar 2000 A
6039552 Mimura Mar 2000 A
6045343 Liou Apr 2000 A
6053716 Riegger et al. Apr 2000 A
6071103 Hirano et al. Jun 2000 A
6077058 Saitou et al. Jun 2000 A
6079965 Delmotte Jun 2000 A
6086341 Fukuhara et al. Jul 2000 A
6102682 Kim Aug 2000 A
6102683 Kirsten Aug 2000 A
6106242 Sung Aug 2000 A
6109901 Nakamura et al. Aug 2000 A
6117916 Allam et al. Sep 2000 A
6132195 Ikoma et al. Oct 2000 A
6139296 Okajima et al. Oct 2000 A
6142756 Hashimoto et al. Nov 2000 A
6146774 Okamoto et al. Nov 2000 A
6149408 Holt Nov 2000 A
6164263 Saint-Hilaire et al. Dec 2000 A
6164934 Niihara et al. Dec 2000 A
6176687 Kim et al. Jan 2001 B1
6195889 Gannaway Mar 2001 B1
6205788 Warren Mar 2001 B1
6205960 Vallejos Mar 2001 B1
6210130 Kakuda et al. Apr 2001 B1
6213732 Fujio Apr 2001 B1
6220825 Myers et al. Apr 2001 B1
6225706 Keller May 2001 B1
6230503 Spletzer May 2001 B1
6233955 Egera May 2001 B1
6241496 Kim et al. Jun 2001 B1
6250899 Lee et al. Jun 2001 B1
6261073 Kumazawa Jul 2001 B1
6270329 Oshima et al. Aug 2001 B1
6273694 Vading Aug 2001 B1
6280168 Matsumoto et al. Aug 2001 B1
6283728 Tomoiu Sep 2001 B1
6283737 Kazakis et al. Sep 2001 B1
6287098 Ahn et al. Sep 2001 B1
6287100 Achtelik et al. Sep 2001 B1
6290472 Gannaway Sep 2001 B2
6290882 Maus et al. Sep 2001 B1
6299425 Hirano et al. Oct 2001 B1
6302664 Kazakis et al. Oct 2001 B1
6309196 Jones et al. Oct 2001 B1
6312233 Ahn et al. Nov 2001 B1
6312240 Weinbrecht Nov 2001 B1
6318981 Ebara et al. Nov 2001 B1
6328540 Kosters et al. Dec 2001 B1
6328545 Kazakis et al. Dec 2001 B1
6336336 Kawaminami et al. Jan 2002 B1
6336794 Kim Jan 2002 B1
6336797 Kazakis et al. Jan 2002 B1
6336799 Matsumoto et al. Jan 2002 B1
6336800 Kim et al. Jan 2002 B1
6354262 Wade Mar 2002 B2
6361306 Hinzpeter et al. Mar 2002 B1
6371745 Bassine Apr 2002 B1
6379480 Girault et al. Apr 2002 B1
6398520 Han Jun 2002 B2
6409488 Ikoma et al. Jun 2002 B1
6409490 Nemit, Jr. et al. Jun 2002 B1
6413061 Esumi et al. Jul 2002 B1
6416302 Achtelik et al. Jul 2002 B1
6418927 Kullik Jul 2002 B1
6425732 Rouse et al. Jul 2002 B1
6428284 Vaisman Aug 2002 B1
6435850 Sunaga et al. Aug 2002 B2
6440105 Menne Aug 2002 B1
6447268 Abramopaulos Sep 2002 B1
6447274 Horihata et al. Sep 2002 B1
6461119 Timuska Oct 2002 B1
6478560 Bowman Nov 2002 B1
6488488 Achtelik et al. Dec 2002 B2
6524086 Matsumoto et al. Feb 2003 B2
6526751 Moeckel Mar 2003 B1
6533558 Matsumoto et al. Mar 2003 B1
6547545 Jonsson et al. Apr 2003 B1
6550442 Garcia Apr 2003 B2
6557345 Moeckel May 2003 B1
6582183 Eveker et al. Jun 2003 B2
6589034 Vorwerk et al. Jul 2003 B2
6592347 Matsumoto et al. Jul 2003 B2
6595767 Hinzpeter et al. Jul 2003 B1
6599113 Lee Jul 2003 B1
6616428 Ebara et al. Sep 2003 B2
6651458 Ebara et al. Nov 2003 B1
6658885 Zhou et al. Dec 2003 B1
6669450 Jeong Dec 2003 B2
6672063 Proeschel Jan 2004 B1
6672263 Vallejos Jan 2004 B2
6676393 Matsumoto et al. Jan 2004 B2
6685441 Nam Feb 2004 B2
6692242 Matsumoto et al. Feb 2004 B2
6716007 Kim et al. Apr 2004 B2
6722867 Murata Apr 2004 B2
6732542 Yamasaki et al. May 2004 B2
6733723 Choi et al. May 2004 B2
6745767 Kullik et al. Jun 2004 B2
6746223 Manole Jun 2004 B2
6748754 Matsumoto et al. Jun 2004 B2
6749405 Bassine Jun 2004 B2
6749416 Arndt et al. Jun 2004 B2
6751941 Edelman et al. Jun 2004 B2
6752605 Dreiman et al. Jun 2004 B2
6764279 Meshenky Jul 2004 B2
6769880 Hogan et al. Aug 2004 B1
6769890 Vigano′ et al. Aug 2004 B2
6796773 Choi et al. Sep 2004 B1
6799956 Yap et al. Oct 2004 B1
6813989 Santiyanont Nov 2004 B2
6817185 Coney et al. Nov 2004 B2
6824367 Matsumoto et al. Nov 2004 B2
6824370 Takatsu Nov 2004 B2
6827564 Becker Dec 2004 B2
6854442 Satapathy et al. Feb 2005 B2
6858067 Burns et al. Feb 2005 B2
6860724 Cho et al. Mar 2005 B2
6877951 Awdalla Apr 2005 B1
6881044 Thomas, Jr. et al. Apr 2005 B1
6884054 Shimada Apr 2005 B2
6892454 Matsumoto et al. May 2005 B2
6892548 Choi et al. May 2005 B2
6896497 Kuo May 2005 B2
6907746 Sato et al. Jun 2005 B2
6910872 Cho et al. Jun 2005 B2
6915651 Hille et al. Jul 2005 B2
6929455 Dreiman et al. Aug 2005 B2
6931866 Sato et al. Aug 2005 B2
6932588 Choi et al. Aug 2005 B2
6935853 Lee et al. Aug 2005 B2
6962486 Lee et al. Nov 2005 B2
6974314 Matsumoto et al. Dec 2005 B2
6983606 Brown Jan 2006 B2
7008199 Matsumoto et al. Mar 2006 B2
7011183 Picouet Mar 2006 B2
7028476 Proeschel Apr 2006 B2
7029252 Masuda et al. Apr 2006 B2
7040880 Hasegawa et al. May 2006 B2
7059842 Lee et al. Jun 2006 B2
7070395 Lee et al. Jul 2006 B2
7083689 Park Aug 2006 B2
7101161 Matsumoto et al. Sep 2006 B2
7104764 Lee et al. Sep 2006 B2
7128540 Tadano et al. Oct 2006 B2
7131821 Matumoto et al. Nov 2006 B2
7134845 Lee et al. Nov 2006 B2
7140844 Lee et al. Nov 2006 B2
7144224 Kim et al. Dec 2006 B2
7150602 Choi et al. Dec 2006 B2
7150608 Cho et al. Dec 2006 B2
7153109 Cho et al. Dec 2006 B2
7168257 Matsumoto et al. Jan 2007 B2
7172016 Meshenky et al. Feb 2007 B2
7174725 Tadano et al. Feb 2007 B2
7175401 Cho et al. Feb 2007 B2
7186100 Cho et al. Mar 2007 B2
7189068 Thomas, Jr. et al. Mar 2007 B2
7191738 Shkolnik Mar 2007 B2
7192259 Lee Mar 2007 B2
7195451 Awdalla Mar 2007 B1
7217110 Dreiman May 2007 B2
7220108 Cho et al. May 2007 B2
7223081 Lee et al. May 2007 B2
7223082 Sato et al. May 2007 B2
7226275 Lee et al. Jun 2007 B2
7232291 Choi et al. Jun 2007 B2
7241239 Tanaka Jul 2007 B2
7252487 Sato Aug 2007 B2
7270521 Sung et al. Sep 2007 B2
7281914 Lee Oct 2007 B2
7284372 Crow Oct 2007 B2
7290994 Kitaichi et al. Nov 2007 B2
7293966 Cho et al. Nov 2007 B2
7293970 Sato Nov 2007 B2
7300259 Cho et al. Nov 2007 B2
7302803 Tadano et al. Dec 2007 B2
7309217 Cho et al. Dec 2007 B2
7322809 Kitaura et al. Jan 2008 B2
7334428 Holdsworth Feb 2008 B2
7344367 Manole Mar 2008 B2
7347676 Kopelowicz Mar 2008 B2
7354250 Sung et al. Apr 2008 B2
7354251 Cho et al. Apr 2008 B2
7361005 Sato Apr 2008 B2
7363696 Kimura et al. Apr 2008 B2
7377755 Cho May 2008 B2
7377956 Cheney, Jr. et al. May 2008 B2
7380446 Baeuerle et al. Jun 2008 B2
7381039 Sato Jun 2008 B2
7381040 Ogasawara et al. Jun 2008 B2
7381356 Shimada et al. Jun 2008 B2
7390162 Awdalla Jun 2008 B2
7399170 Aya et al. Jul 2008 B2
7401475 Hugenroth et al. Jul 2008 B2
7431571 Kim et al. Oct 2008 B2
7435062 Tadano et al. Oct 2008 B2
7435063 Tadano et al. Oct 2008 B2
7438540 Sato Oct 2008 B2
7438541 Aya et al. Oct 2008 B2
7458791 Radziwill Dec 2008 B2
7462021 Ebara et al. Dec 2008 B2
7481631 Park et al. Jan 2009 B2
7481635 Nishikawa et al. Jan 2009 B2
7488165 Ogasawara et al. Feb 2009 B2
7491042 Matsumoto et al. Feb 2009 B2
7507079 Fujisaki Mar 2009 B2
7510381 Beckmann et al. Mar 2009 B2
7520733 Matumoto et al. Apr 2009 B2
7524174 Nishikawa et al. Apr 2009 B2
7540727 Byun et al. Jun 2009 B2
7556485 Kanayama et al. Jul 2009 B2
7563080 Masuda Jul 2009 B2
7563085 Sakaniwa et al. Jul 2009 B2
7566204 Ogasawara et al. Jul 2009 B2
7572116 Nishikawa et al. Aug 2009 B2
7581937 Nishikawa et al. Sep 2009 B2
7581941 Harada et al. Sep 2009 B2
7584613 Crow Sep 2009 B1
7585162 Nishikawa et al. Sep 2009 B2
7585163 Nishikawa et al. Sep 2009 B2
7588427 Bae et al. Sep 2009 B2
7588428 Masuda Sep 2009 B2
7597547 Ha et al. Oct 2009 B2
7600986 Matumoto et al. Oct 2009 B2
7604466 Dreiman et al. Oct 2009 B2
7607904 Masuda Oct 2009 B2
7611341 Byun et al. Nov 2009 B2
7611342 Matsumoto et al. Nov 2009 B2
7611343 Matsumoto et al. Nov 2009 B2
7618242 Higuchi et al. Nov 2009 B2
7621729 Matsumoto et al. Nov 2009 B2
7641454 Ueda et al. Jan 2010 B2
7650871 See Jan 2010 B2
7658599 Lee et al. Feb 2010 B2
7661940 Maeng Feb 2010 B2
7665973 Hwang Feb 2010 B2
7681889 Tsuboi et al. Mar 2010 B2
7690906 Tado et al. Apr 2010 B2
7703433 Webster Apr 2010 B2
7713040 Kimura et al. May 2010 B2
7717686 Kondo et al. May 2010 B2
7722343 Hirayama May 2010 B2
7726960 Oui et al. Jun 2010 B2
7748968 Morozumi Jul 2010 B2
7753663 Shimizu et al. Jul 2010 B2
7762792 Tadano et al. Jul 2010 B2
7768172 Takahata et al. Aug 2010 B2
7775044 Julien et al. Aug 2010 B2
7775782 Choi et al. Aug 2010 B2
7780426 Cho et al. Aug 2010 B2
7780427 Ueda et al. Aug 2010 B2
7789641 Masuda Sep 2010 B2
7793516 Farrow et al. Sep 2010 B2
7798787 Matumoto et al. Sep 2010 B2
7798791 Byun et al. Sep 2010 B2
7802426 Bollinger Sep 2010 B2
7802972 Shimizu et al. Sep 2010 B2
7806672 Furusho et al. Oct 2010 B2
7837449 Tadano et al. Nov 2010 B2
7841838 Kawabe et al. Nov 2010 B2
7854602 Bae et al. Dec 2010 B2
7871252 Bae et al. Jan 2011 B2
7874155 McBride et al. Jan 2011 B2
8240142 Fong et al. Aug 2012 B2
20110023814 Shkolnik et al. Feb 2011 A1
20110023977 Fong et al. Feb 2011 A1
20120051958 Santos et al. Mar 2012 A1
Foreign Referenced Citations (13)
Number Date Country
223597 Sep 1942 CH
74152 Feb 1893 DE
3611395 Oct 1987 DE
61-277889 Dec 1986 JP
02-140489 May 1990 JP
2009-185680 Aug 2009 JP
2009-185680 Aug 2009 JP
1150401 Apr 1985 SU
WO 9518945 Jul 1995 WO
WO9943926 Sep 1999 WO
WO 0120167 Mar 2001 WO
WO201017199 Feb 2010 WO
WO 2012030741 Mar 2012 WO
Non-Patent Literature Citations (19)
Entry
Non-Final Office Action dated Jan. 6, 2017 in corresponding U.S. Appl. No. 15/264,559 (14 pages).
Brown, Royce N., RNB Engineering, Houston, Texas, “Compressors: Selection and Sizing”, Gulf Professional Publishing, 3rd Edition, 2005 Elsevier Inc.
Kreith, Frank, “The CRC Handbook of Thermal Engineering”, Library of Congress Cataloging-in-Publication Data, 2000 by CRC Press LLC.
Avallone, Eugene A., et al., “Marks' Standard Handbook for Mechanical Engineering”, Eleventh Edition, 2007, 1996, 1987, 1978 by the McGraw-Hill Companies, Inc.
“Basic Refrigeration and Air Conditioning”, Third Edition, 2005, 1996, 1982, by Tata McGraw-Hill Publishing Company Limited.
Budynas, Richard G. and Nisbett, J, Keith, “Shigley's Mechanical Engineering Design”, 8th edition, 2008 by McGraw Hill Higher Education.
Oberg, Erik et al, “Machinery's Handbook”, 27th edition, 2004, by Industrial Press Inc, New York, NY.
International Search Report and Written Opinion as issued for International Application No. PCT/US2011/049599, dated Feb. 28, 2013.
International Preliminary Report on Patentability as issued for International Application No. PCT/US2011/049599, dated Mar. 14, 2013.
Coney, et al., “Development of a Reciprocating Compressor Using Water Injection to Achieve Quasi-Isothermal Compression”, International Compressor Engineering Conference, Purdue University, School of Mechanical Engineering, Purdue e-Pubs, 2002, 10 pgs.
Office Action issued for U.S. Appl. No. 13/220,528, dated Mar. 24, 2014.
Search and Examination Report issued in Gulf Coast Patent Application No. GC 2011-19481, dated Nov. 26, 2014.
First Office Action as issued in Chinese Patent Application No. 201180052573.3, dated May 6, 2015.
Engineering Data Book, SI Version, vol. I, Sections 1-15, 2004, 68 pages.
Ohama, T. et al., “High Pressure Oil-Injected Screw Gas Compressors (API 619 Design) for Heavy Duty Process Gas Applications,” Proceedings of the Thirty-Third Turbomachinery Symposium, 2004, pp. 49-56.
Ohama, T. et al., “Process Gas Applications Where API619 Screw Compressors Replaced Reciprocating and Centrifrugal Compressors,” Proceedings of the Thirty-Fifth Turbomachinery Symposium, Sep. 25-28, 2006, pp. 89-96.
Wrigley, B., “Heat Exchanger”, retrieved online URL:<http:// www.real-world-physics-problems. com/heat-exchanger.html>, 2009, pp. 1-28.
Panao, Miguel R.O. et al., Intermittent Spray Cooling: A New Technology for Controlling Surface Temperature, International Journal of Heat and Fluid Flow, vol. 30, No. 1, Feb. 2009, pp. 117-130.
Office Action Canadian Patent Application No. 2,809,945 dated Jun. 28, 2017.
Related Publications (1)
Number Date Country
20160131138 A1 May 2016 US
Provisional Applications (3)
Number Date Country
61485006 May 2011 US
61378297 Aug 2010 US
61770989 Feb 2013 US
Divisions (1)
Number Date Country
Parent 13782845 Mar 2013 US
Child 14994964 US
Continuation in Parts (2)
Number Date Country
Parent 13220528 Aug 2011 US
Child 13782845 US
Parent PCT/US2011/049599 Aug 2011 US
Child 13782845 US