Patent Application
20220299033
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
In the pumping world dominated by horizontal pumps of all different styles, mechanical seals or shaft packing glands are the most troublesome and highest maintenance cost items over all other pump components.
Vertical pumps that have high temperature applications are known. However, such pumps typically apply standard pump components that do not permit elongation or shortening through a telescoping feature.
The answer to eliminating these problems and their associated expenses is to remove both components and reposition the pump components vertically with a gas seal column encasing a drive shaft between a drive motor and a pump. The drive motor may be sealed or unsealed, and the gas seal column and the pump may form a sealed unit that is pressurized for product containment. However, elevated temperature applications may require a corrosion resistant lined metallic outer column or for special applications a metallic outer column supporting a telescoping high temperature corrosion resistant liner described herein.
These numerous benefits, and other numerous benefits listed herein, may be realized by utilizing the invention:
Considering all of the above it can easily be expected that the total life cycle cost of a gas seal column pump, especially a structural metal column with a telescoping corrosion resistant liner optimized for use in elevated temperature situations, will be significantly lower than for a similar performing mechanical seal or packing pump.
Certain illustrative embodiments illustrating organization and method of operation, together with objects and advantages may be best understood by reference to the detailed description that follows taken in conjunction with the accompanying drawings in which:
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure of such embodiments is to be considered as an example of the principles and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings.
The terms “a” or “an”, as used herein, are defined as one or more than one. The term “plurality”, as used herein, is defined as two or more than two. The term “another”, as used herein, is defined as at least a second or more. The terms “including” and/or “having”, as used herein, are defined as comprising (i.e., open language). The term “coupled”, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically.
Reference throughout this document to “one embodiment”, “certain embodiments”, “an embodiment” or similar terms means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments without limitation.
The gas seal column pump (hereinafter “invention”) may comprise a pump drive motor having a sealed housing or an unsealed housing, a gas seal column, a seal gas control box, and a pump. The pump drive may comprise a pump drive motor and a cooling fan. The pump drive motor may comprise a drive shaft that is extended to reach the pump through the gas seal column. The pump drive motor may further comprise a pressurized housing or an unpressurized housing. The cooling fan may be mounted to the pump drive motor externally to cool the pump drive motor instead of driving a fan from an extension of the drive shaft of the pump drive motor through the top of the pump drive motor. Alternatively, ducted cooling from a remote source may be used to cool the pump drive motor.
The seal gas may be clean and pressurized and may be sourced locally or remotely. The first choice for the seal gas would be clean air that is free of corrosive fumes. Alternatively, a specialized gas may be used if air is incompatible with a product being pumped. If the seal gas that is selected to be used cannot be released to the environment after use because of cost, toxicity, contamination, or other reasons then the seal gas may be directed to a local gas treatment system or collected in a tank for later treatment. After treatment, the seal gas may be reused or disposed of.
The gas seal column may be operable to encase the drive shaft component of the pumping system and may function as a replacement for mechanical seals and packing by using pressure of the seal gas to control a product level within the gas seal column, during startup, when pumping, during shutdown, or in standby when gas seal column controls are activated.
The gas seal column may comprise a top mounting panel at the top end of the gas seal column. A circular groove in the top mounting panel may capture a first O-ring which is operable to pressure seal the interface between the pump drive motor and the gas seal column.
An inlet pipe connection and an outlet pipe connection located in the upper quarter of the gas seal column may allow the seal gas to flow in and out of the gas seal column. A purge gas inlet valve and a purge gas discharge valve may control the flow of the seal gas.
The gas seal column may or may not comprise as assembly of Splash Quieting Discs (SQDs) and Anti-Rotation Panels (ARPs). Each SQD is a structural element that may be formed as a disc with an outside diameter that is an easy slip fit into the seal column and with an inside diameter slightly larger than the shaft that will pass through it to ensure no contact with the shaft. The SQDs may be perforated as needed to allow for passage of the product. While described as a disc, each SQD may function as a porous horizontal barrier to the product and consequently may be made in a large variety of different structural configurations, including, but not limited to, discs, coils, cylinders, mesh, or other structures, that still fall within the spirit of the invention.
ARPs are vertical structural elements that may have a width the same as the outside radius minus the inside radius of the SQDs.
SQDs may be attached to and separated by ARPs and positioned and fastened at a right angle to the flat plane of the SQD, as shown in
In an application where the product supply source and the product discharge outlet are located above the pump drive motor, when the pump drive motor switches from ‘on’ to ‘off, the product being pumped may surge into the column in a turbulent manner.
With an SQD and ARP assembly in place, the product being pumped may rapidly fill the cavity below the bottom SQD. The product will gradually fill up the cavity below the second SQD, below the third SQD, and so on because of the small clearances between the SQD, the column and the shaft, and depending upon the type and number of perforations in the SQD. In this way the SQDs prevent splashing damage to the pump drive motor and allow time for the product control system to react as needed to minimize or eliminate damage to the pump drive motor.
The gas seal column may comprise a plurality of level sensors. The plurality of level sensors may detect the product level within the gas seal column and may report the product level to the seal gas control box. Based upon input from the plurality of level sensors, the seal gas control box may be adapted to monitor the product level, may report the product level, may alert an operator, and may control the product level of the product that may come into the gas seal column during operating and standby conditions, when the seal gas control box is energized by a purge gas control switch. As a non-limiting example, the seal gas control box may be adapted to alert the operator by activating flashing indicators, sending text messages, pages, or emails, sounding audible transducers, or combinations thereof if the product level exceeds a predetermined alert threshold. As a further non-limiting example, the seal gas control box may shut down the pump and possibly other components if the product level exceeds a predetermined shutdown threshold.
In an embodiment there may be four level sensors. The four level sensors may be equally spaced along the gas seal column. A first level sensor may be located at the lowest level of the gas seal column. A second level sensor, a third level sensor, and a fourth level sensor may be located above the first level sensor in that order, with the fourth level sensor being at the highest level within the gas seal column.
At pump start up, the purge gas control switch may be activated manually or automatically. Responsive to activating of the purge gas control switch, the seal gas control box may begin a low volume purge gas flow throughout the system by opening a purge gas valve and leaving a first gas valve and a second gas valve closed. In some embodiments, the opening and closing of the purge gas valve, the first gas valve, a second gas valve, and the gas discharge valve may be controlled by relays or other controls located within the seal gas control box.
In some embodiments, the purge gas valve, the first gas valve, and the second gas valve may provide differing flow rates of the seal gas when in the open state. The differing flow rates may result in differing pressures applied to the product within the gas seal column. The smallest flow rate, and therefore the lowest pressure on the product within the gas seal column, may result from having only the purge gas valve open. The highest flow rate, and therefore the highest pressure on the product within the gas seal column, may result from having the purge gas valve, the first gas valve, and the second gas valve all open. Because the seal gas may be introduced into the top of the gas seal column, the pressure applied to the product from the seal gas may work to force the product level down.
The seal gas control box may become aware that the product has entered the gas seal column when the first level sensor detects the product and opens the purge gas valve. If the product is detected by the second level sensor, the seal gas control box may attempt to stop the product from rising further in the gas seal column by increasing the pressure of the seal gas within the gas seal column. The seal gas control box may open the first gas valve, thus releasing a higher flow of the seal gas into the gas seal column. If this works and the product level drops, then the second level sensor may reflect that the product is no longer contacting the second level sensor. However, the seal gas control box may retain the first gas valve in the open state. When the first level sensor indicates that the product level has dropped below the first level sensor, the seal gas control box may close the first gas valve, the purge gas valve, and the gas discharge valve.
Alternatively, if the product level continues to rise above the second level sensor and is detected by the third level sensor, the seal gas control box may activate and latch a relay that opens the second gas valve, thus releasing an even higher flow of gas into the gas seal column to further increase gas pressure to push the product down in the gas seal column. The seal gas control box may additionally be adapted to send an alert to the operator reporting that the product is appearing at a higher level in the gas seal column than is normally expected. The higher level of gas flow will continue until the product is driven down to the first level sensor which will open and deactivate the two latched relays that will then close the first gas valve, the second gas valve, the purge gas valve, and the gas discharge valve.
Alternatively, if the product level continues to rise and is detected by the fourth level sensor, the seal gas control box may be adapted to initiate a controlled, complete shutdown of the system and close all valves to maintain the sealed integrity of the total pump housing and to prevent equipment damage or other collateral damage from occurring. This shutdown sequence allows the operator to investigate what is causing the condition and to correct the problem.
The first level sensor may be located slightly above the minimum priming level for the pump. When the pump is stopped, inlet or outlet conditions may cause the product to rise or drop in the gas seal column. A rise in the product level may be controlled as previously described. Responsive to a drop in the product level below the first level sensor, the seal gas control box may deactivate the relay that holds the purge gas valve open. Closing the purge gas valve may stop purge gas flow until the product rises to reach the first level sensor. The seal gas control box may function in this manner whether the pump is operating or in standby mode as long as the seal gas control box is activated.
The description of sensing and control presented herein is by way of illustration only. There are many other sensing and control techniques that may be applied which a person having ordinary skill in the art will recognize as falling within the spirit and scope of the invention.
The pump illustrated is a centrifugal pump comprising a pump casing with an inlet and an outlet and an O-ring to seal a cover plate to the pump casing. The pump casing may be sealed to the gas seal column with second O-ring, completing the seal for the entire assemblage. The drive motor, the gas seal column, and the pump may or may not comprise a single, sealed unit. In an embodiment, the drive motor may form a portion of the single, sealed unit, may be separately sealed from the sealed unit, or may remain unsealed.
The pump may comprise a dual impellor to move the product. An auxiliary impellor may be mounted on the back of a main impellor. The auxiliary impellor may be a larger diameter than the main impellor. The auxiliary impellor may constitute a hydrodynamic shaft seal and may prevent the flow of the product into the gas seal column during pumping operations.
The drive shaft may be a sleeved shaft to protect the drive shaft from corrosion.
In some applications, the pump may require operation at an elevated temperature. In those cases where growth in the length of a monolithic corrosion resistant column might interfere with pump operation, a lined version of the gas seal column can be used. In
Alternatively, if available, and suitable for the application a bellows liner could be used in place of the telescoping liner.
The pumping system shown in
Referring to
The bearing shaft adapter interfaces may be sealed by additional O-rings to maintain the hermetic seal integrity of the pump drive motor envelope for those embodiments in which the drive motor is sealed or forms a portion of the single sealed unit. However, in an embodiment in which the drive motor is not sealed, additional O-rings are not utilized in the implementation.
Since a sealed unit encloses a fixed volume of empty space, the sealed unit passively assists in controlling the level of the product trying to rise in the gas seal column. Passive assistance may result from Boyles Law which states that “the pressure of an ideal gas is inversely proportional to the volume of the ideal gas at a constant temperature”.
P1×V1=P2×V2
where P1 is a first pressure,
V1 is a first volume,
P2 is a second pressure, and
V2 is a second volume.
Simply put—if you halve the available volume of a fixed amount of gas you will double the pressure.—In accordance with Boyle's Law, as the volume available for the seal gas is reduced, the pressure of the seal gas increases and the seal gas may become more effective in countering the rise of the product.
As experience is gained through the introduction and application of this invention consideration should be given to the operational benefits that might be optimized by decreasing empty space in the pump drive motor housing and also the internal shape and size of the gas seal column around the drive shaft, all of which may affect system response time.
In an embodiment, the pump device herein described may use a wider variety of readily available unsealed motors as the driving mechanism, which may be use in conjunction with a gas shaft seal for the gas seal column in space 560. A pump having an unsealed motor provides all of the product handling features of a fully sealed motor embodiment.
The gas seal column and the pump casing may still be sealed together at their interface and, in conjunction with a gas shaft seal mounted in the top mounting panel of the gas seal column. This constitutes a sealed enclosure when the pump drive motor shaft is slid through the gas shaft seal and the pump drive motor is secured to the top mounting panel. The embodiment is illustrated in
Turning now to
The gas seal column controls 310, comprising the seal gas control box 250, the purge gas valve 254, the first gas valve 256, and the second gas valve 258, may control the flow of the seal gas 208 into the invention 100 when activated by the purge gas control switch 252. The seal gas 208 may be introduced into the gas seal column 220 via the gas inlet pipe connection 230 and may exit the gas seal column 220 via the gas discharge outlet pipe connection 232. The seal gas 208 may pressurize the gas seal column 220 to force the product downwards. The gas pressure may be regulated by the seal gas control box 250 by opening and closing the purge gas inlet valve 254, the first gas valve 256, and the second gas valve 258. The gas discharge valve 234 may prevent or permit the seal gas 208 from exiting the gas seal column 220 and may also be under control of the seal gas control box 250. The seal gas control box 250 may also control power to the pump drive motor 202 such that the seal gas control box 250 may shut down the system if necessary.
The first level sensor 240, the second level sensor 242, the third level sensor 244, and the fourth level sensor 246 may detect the product level within the gas seal column 220 and may report the product level to the seal gas control box 250.
The drive shaft 214 may turn the main impellor 290 in the pump 270 to move the product from the inlet 274 to the outlet 276. The auxiliary impellor 292 may be coupled to the main impellor 290 and may constitute a hydrodynamic seal to resist the flow of the product into the gas seal column 220. The gas seal column 220 may comprise the plurality of anti-rotation panels 238 and the plurality of splash quieting discs 236.
Turning now to
Turning now to
Turning now to
While certain illustrative embodiments have been described, it is evident that many alternatives, modifications, permutations and variations will become apparent to those skilled in the art in light of the foregoing description.
