Patent Grant
12320347
The present disclosure relates to air compressors, like reciprocating air compressors. More specifically, the present disclosure is directed toward an intelligent controller for a reciprocating air compressor, and methods of use thereof.
Generally speaking, an air compressor is a pneumatic device that converts power, using an electric motor, diesel or gasoline engine, etc., into potential energy stored in pressurized air. By one of several methods, an air compressor forces more and more air into a storage tank, increasing the pressure to create the compressed air. When the tank's pressure reaches its engineered upper limit, the air compressor shuts off. The compressed air, then, is held in the tank until called into use. The energy contained in the compressed air can be used for a variety of applications, utilizing the kinetic energy of the air as it is released and the tank depressurizes. When tank pressure reaches its lower limit, the air compressor turns on again by use of a pressure switch, or some pressure-sensing control system, and re-pressurizes the tank. An air compressor must be differentiated from a liquid pump because it works for any gas/air.
Centrifugal compressors represent the smallest segment of the industrial compressor market. These are large capacity complex machines with motor power greater than 400-hp. These compressors cost over $200 k US and are typically found in very large factories, processing facilities and chemical plants. Electronic controls are standard on centrifugal compressors. Hardware is typically an industrial PLC or similar type unit with display, multiple inputs and outputs. This category of compressor is complex and requires specialized logic and software for the compressor to operate and protect the unit from catastrophic failure. Centrifugal air compressors operate using a target pressure control method that requires the operator to set a desired target pressure. The compressor controller will utilize different methods of modulating output of the compressor in an effort to match demand for compressed air and maintain pressure close to the target pressure. These compressors rarely turn off the motor since large motors over 400 hp require hours of off time before starting so they will unload the compressor instead or operate at a reduced load and discharge excess air to the atmosphere. These are very complex with multiple compressor stages, cooling systems, electrically modulated valves and safety control parameters to monitor. These compressors have sophisticated logic to operate several subsystems in an effort to maintain pressure close to the desired value or within a user defined range and to prevent the compressor from failing.
Rotary screw compressors are a larger segment of the industrial compressor market with medium capacity covering a range from 20-500-hp. These units range in price from $8 k-$150 k. This type of compressor is in most factories worldwide. Rotary style air compressors have used an electronic controller or a combination of electronic and pneumatic controls for the past 30 years. The electronic controller and display panel are mounted within an electrical enclosure. The primary purpose of the controller is to protect the compressor and operate the unit within a user-defined pressure range. The controller hardware sophistication varies based on the size and cost of the air compressor. Rotary screw compressors will typically operate without turning off the motor. The compressor controller will have a user defined upper and lower pressure setting. At the upper pressure value the compressor unloads by closing an inlet valve, reducing the inlet air flow almost 100% and opening an exhaust blowdown valve to relieve pressure in a sump. The pressure settings of the compressor are fixed until an operator manually changes them. When this compressor unloads, a timer is started that counts down towards a command to turn off the motor. This timer duration is set by the operator and is rarely adjusted from factory conservative settings. There is a more sophisticated control method that allows the operator to select the number of motor starts per hour the compressor can use. At the start of every hour the counter resets to zero starts used. If the operator sets the compressor to 6 starts per hour, the first time the compressor reaches the upper pressure setpoint the compressor will unload and turn off the motor. When pressure reaches the start value, the compressor will start the motor and load the compressor. The next time the compressor reaches the upper pressure setpoint it unloads. The controller divides the remaining time in the hour by the number of remaining motor starts allowed to define the minimum cycle time. This time is used to determine how long the compressor needs to run unloaded before stopping the motor. It does not evaluate demand in real time and will not adjust off time based on a cycle duration prediction. With larger motors they do not evaluate operation to predict heat load and evaluate that against motor design to calculate off duration, it is a simple fixed number of starts per hour that requires an operator to adjust it, which rarely occurs. It is common to find variable speed drive controls for rotary screw compressors and there is one currently known manufacturer that uses it on a smaller 10 hp reciprocating air compressor. The electronic controller is sophisticated in how it controls the speed of the motor but this logic is limited to only controlling motor speed. From an air compressor perspective, the controller operates based on a target pressure with an upper pressure limit and a motor speed range. The user sets a target pressure and the controller will speed up or slow down the motor in an attempt to maintain pressure close to the target value. When the motor is reduced to minimum speed, the pressure will continue to rise if demand is less than the compressor output until pressure reaches the stop pressure value and the motor will stop. Pressure will decay until reaching target pressure triggering the compressor to start the motor and control to target pressure again. All operating settings are set by the operator.
The largest segment of the air compressor market by population, or number of units sold annually, is the small reciprocating air compressor. Reciprocating air compressors are often referred to as piston-style air compressors. In the industrial market, these units range from 5-30 hp and are priced from $1 k-$10 k. There is also a lower tier commercial or hobby segment for this product which are lower-cost units designed for light-duty, ranging in size from ¼ hp-5 hp and price range from $100-$1500. All these piston style reciprocating air compressors have very low value per unit for parts and service. Consequently, there has been very little done to apply new technology since it would add cost.
There is also a specialty reciprocating air compressor market for high-pressure air and gasses. These units are in the $50 k-$900 k range and may utilize a PLC-type controller to monitor and operate these larger, more costly units. Operation is still very basic, limiting the compressor to start and stop or load and unload at user-defined pressure values. This is a very small segment of the compressor market.
The common industrial reciprocating air compressor has been controlled the same way for the past century. It is a low-cost, high-volume product that is very price sensitive. The compressor is commonly operated using a simple start/stop control logic using a mechanical spring and diaphragm pressure switch. Air pressure from the tank presses against the diaphragm surface. Working against the force of the diaphragm is a spring and lever assembly. As the force compresses the spring it will eventually trip the leverage device that opens an electronic contactor or switch, isolating power to the motor and stopping the compressor. The opposing force of the spring is adjusted by turning a screw to adjust load on the spring, influencing the pressure required to trip the switch. The electronic contact surface on the switch is typically limited to electrical loads of 5 hp or less. Above that load a secondary contactor is used to support opening and closing the circuit for primary power to the motor. This contactor is opened and closed using a magnetic coil that is energized using a small electrical signal that passes through the pressure switch. The pressure switch still operates the same way for larger horsepower units; it just does not support the total electrical load. As pressure decays in the system the force acting on the diaphragm is reduced. To provide some difference between the stop and start pressures on the pressure switch there is a secondary spring that holds the contactor open. The contactor will not open until the force acting on the primary spring and lever is sufficient to pull the contactor closed. For most pressure switches used today, this differential pressure spring is not adjustable. For some industrial compressors the pressure switch is factory set and is not adjustable at all. These units will typically cycle the compressor on at 125 psig and off at 175 psig. These pressure switches are cheap and operation is not very repeatable so the actual start and stop pressures can vary throughout the day and over the life of the switch. This simple pressure switch control is used by all manufacturers.
With regards to reduced pressure starting, the small reciprocating air compressor should not start under pressure. This can either cause the unit to overload the electrical circuit and trip an electrical safety, or for some units, the compressor will start but the high load taxes the motor and mechanical components. Repeated loaded starts will eventually cause the electric motor to fail or can cause catastrophic mechanical failure of the compressor. To minimize the potential of this from occurring, the reciprocating air compressor uses a check valve that allows air to exit the compressor pump into the tank while it is loaded but does not allow air to travel from the tank back to the compressor when the pump is unloaded or off. When the compressor turns off, a small valve is opened to exhaust air trapped between the pump and the check valve. For many reciprocating air compressors this valve is mounted on the pressure switch and the same lever that opens the electrical contacts is used to depress a small pin that opens the valve. This holds that valve in an open position until the pressure switch closes the electrical contact moving the lever and closing the valve. Some compressors use another style of mechanical switch that opens the blowdown valve when the pump stops rotating. Functionally they are the same, open the valve when the pump stops and close the valve when the pump starts. When the check valve fails it leaks air past the check valve. This air will vent to the atmosphere causing the compressor to run more frequently, increasing energy consumption and thereby reducing life of the compressor. As the leak rate across the check valve increases, back pressure increases ahead of the blowdown valve, thereby, consequently increasing pressure acting on the pump when it starts. This back pressure at every start over time causes the motor to fail or catastrophic failure to the pump due to excess fatigue from every start.
With regards to high demand control options, more costly industrial reciprocating air compressors have a secondary control option used when demand for compressed air is very high. When demand is high, the motor will turn the pump at full load for extended periods of time. This generates a large heat load in the motor and pump. When the compressor reaches the upper pressure limit the motor turns off, but because the demand for air is high, the pressure drops quickly consequently turning the motor and pump back on before they can dissipate heat. This shortens life expectancy on the motor and pump. To assist with heat dissipation some compressors are equipped with head unloaders that force the intake valves to stay open so the compressor pump cannot build pressure. This allows the pump and motor to turn without generating the heat from compression, allowing the pump and motor to cool before reloading. The head unloaders are pneumatic and require air pressure to engage the head unloaders. This is accommodated using a pneumatic device similar to a pressure switch that opens a circuit to pressurize and open the head unloaders at an upper pressure and close the circuit at a lower pressure. This is adjusted by a mechanism that changes tension on a spring within the device. The compressor cannot select one control mechanism over the other so the pressure switch that turns the motor on/off is always active. To allow this to work the upper pressure setting that activates the head unloader is less than the value that causes the pressure switch to turn off the motor. If there was no way of isolating the pneumatic circuit to the head unloaders, the motor would never turn off. To accommodate using one control method over the other, an operator needs to open an isolation valve on the compressor to activate the pneumatic circuit for the head unloaders and then must close the valve to isolate the circuit. There is no alert telling anyone when to activate this circuit, and unless there is a very obvious application that demands the higher volumes of air, it is not activated, so typically is not fully utilized to protect the mechanical integrity of the air compressor pump and motor as intended.
Compressor protection is done using threshold based alarms or switches. These are limited to over/under pressure alarms, temperature alarms and in some cases rapid cycling alarms. Recently some OEMs are claiming predictive capabilities but this is based on alerting the user of reaching run hour milestones to promote scheduled maintenance. Marketing materials are starting to use terms like AI (artificial intelligence) and machine learning but to date this has been limited to predicting when a compressor will reach a run hour service milestone. Marketing materials promote increased compressor reliability and efficiency using data but this is an assumption based on following preventative maintenance recommendations using time based milestones.
Preventative maintenance schedules for an air compressor will define parts and consumables that should be replaced based on run hour milestone periods or calendar time. Diagnostics to identify an operating issue and parts that require service requires an experienced individual. Some diagnostic capabilities leverage historic data that is reviewed by subject matter experts to predict a component failure. There is no evidence of any autonomous diagnostic capabilities at the component level supported by logic only.
Current control offerings and methods include system controls. There are PC (personal computer) and PLC (programmable logic controller) based offerings, also known as sequencers, that sequence the operation of multiple compressors. This is predominantly an offering for centrifugal and rotary screw type compressors where the energy savings can easily justify the cost of hardware, installation and integration (setup). Some of these controls have logic to alert the user of compressor running hours and when milestone preventative maintenance hours are pending. For efficiency enhancement the sequencers can operate multiple compressors within the same pressure range but this is based on user defined values. Advanced logic will look at changes in pressure with respect to time to delay starting an additional compressor to a sequence if the demand for additional capacity is a short event that could be avoided.
For the small reciprocating air compressor market the control logic is very simple due to cost and will be limited to what is referred to as lead-lag-alternate. This could also be referenced as a lead/lag alternator, as the name implies, it alternates two compressors between the lead and lag position in a sequence. This is used for systems with two reciprocating compressors and is designed to balance run hours and start a second compressor when demand for compressed air exceeds one compressor. The controller is typically mechanical consisting of two pressure switches, two magnetic starters and an alternator. Pressure switch settings are staggered so the lead switch will start a compressor first and then if pressure continues to fall it will trip the lagging pressure switch to start the second compressor. As pressure rises in the system with both compressors running, the lagging compressor switch will be the first to turn off it's associated compressor. The next time the lagging pressure switch starts the compressor the alternator switches the compressor associated with the switch so the next time the pressure rises the switch turns off the other compressor. Similarly, the lead switch will toggle the alternator every time it turns its associated compressor off.
There is only one known electronic controller on the market specifically designed for small reciprocating air compressors. It is marketed by a company called Compressor Controller, a division of SAM Controllers, of Pittsboro, NC. Although their advertisements use a collection of current digital buzz words, like artificial intelligence and edge processing, there is no evidence of this in their product or the operation. It operates like a traditional pressure switch using a digital device and a single pressure transducer mounted on the tank to turn the compressor on and off based on two manually entered pressure values. These values only change if they are manually changed by an operator by turning a screw in the back of the controller. They claim efficiency because the digital controller starts and stops more precisely within the defined pressure band than a pressure switch. The controller incorporates a signal to open and close a solenoid valve to drain condensate from the tank, but this is an established offering that has been around for decades. They market a rupture protection that will turn off the air compressor if there is a catastrophic rupture in a pipe or hose. This consists of a simple timer that will turn the compressor off if it is running beyond a threshold period of time at a pressure less than the start pressure. They also offer what is called sensitivity adjustment but this is just an increased time period before shutting the compressor off and indicating a rupture fault. It does not have a rate of change to calculate demand or incorporate any intelligence to determine on its own if the excessive load is due to an excessive demand for air or an actual rupture. The controller does not have any diagnostic capabilities and is limited to a simple threshold based high temperature alarm using a temperature probe mounted on the surface of the compressor pump. This has been a standard offering on all rotary screw and centrifugal compressors for decades.
There are an assortment of third party compressor controllers on the market for rotary screw and centrifugal compressors. Most manufacturers private label a third-party controller or have one made to their own specifications. To date there are no digital controllers offered on small industrial or commercial reciprocating air compressors from the manufacturer.
Currently there are no known controllers on the market that have any function comparable to the methods disclosed herein. This includes third party analytics tools and cloud-based platforms. Current offerings are limited to marketing collateral using terms like artificial intelligence, machine learning and data analytics. Even the limited manufacturers that have connected compressors with data aggregated on the cloud from thousands of compressors are focusing on rotary screw compressors and nothing with small reciprocating compressors, like the methods disclosed herein.
The instant disclosure recognizes that reciprocating air compressors generally utilize basic control logic that simply toggles the compressor to pump air or stop pumping air between two pressure settings using a mechanical pressure switch.
The instant disclosure also recognizes that the efficiency of a reciprocating air compressor decreases as the pressure at the discharge of the compressor increases.
The instant disclosure also recognizes that the discharge temperature of the air from an air compressor increases as the delivered pressure from the compressor increases. This increased temperature decreases the functional life of many air compressor components and subassemblies
The instant disclosure also recognizes that an electric motor requires a minimum amount of off time based on a percentage of load, time running at load, and motor design. Failing to have sufficient off time will rapidly degrade the motor causing premature motor failure.
The instant disclosure also recognizes that the vast majority of reciprocating air compressors in use and sold are single-stage or two-stage compressors that are air-cooled, and less than 40 hp. The majority of these compressors are not intended to run fully loaded continuously for multiple hours due to limited cooling, wherein compressor life will degrade rapidly as the sustained number of running hours increases the temperature of the compressor pump.
The instant disclosure also recognizes that a large majority of reciprocating air compressors sold and in use have instrumentation limited to a mechanical air pressure gauge and a limited number of units may have an hour counter indicating the accumulated number of hours the motor has been on.
The instant disclosure also recognizes that a large majority of reciprocating air compressors sold and in use operate using a simple stop/start logic controlled by a mechanical pressure switch. This same style of switch has been in use for decades. Some of these compressors may incorporate a secondary control method that utilizes a pneumatic type of pressure switch to load and unload the compressor by applying air to an unloader mechanism that prevents the compressor from pumping air without turning off the motor. This pneumatic control operates at a pressure range within the upper and lower set points of the stop/start switch and requires an operator to open a pneumatic valve to activate this secondary control. The secondary control stays active with the motor running continuously until an operator closes the pneumatic valve to isolate the secondary control circuit.
The instant disclosure also recognizes that the difference between the start and stop pressure is directly proportional to the time the compressor is on while the system is pressurizing and off while pressure decays to the start value. It is common to set the pressure switch stop value to the maximum pressure rating of the compressor and the lower value above an assumed market requirement to maximize the on/off duration. For cost savings, many of the lower-cost compressors have a pressure switch that is not adjustable.
In sum, the instant disclosure recognizes that current controls and/or control logic for reciprocating air compressors lacks the ability to alter operating parameters to improve efficiency, reliability, or to diagnose components of the air compressor that are not operating correctly and require service.
The instant disclosure may be designed to address at least certain aspects of the problems or needs discussed above by providing an intelligent controller for a reciprocating air compressor, and methods of use thereof.
The present disclosure may solve the aforementioned limitations of the currently available air compressors and controls therefor, like reciprocating air compressors and controls for such reciprocating air compressors, by providing an intelligent controller for a reciprocating air compressor, and methods of use thereof. The intelligent controller for the reciprocating air compressor may generally include a processor, a plurality of sensors, and a plurality of peripheral devices. The plurality of sensors may be in communication with the processor. The plurality of sensors may be configured to read operating data of the reciprocating air compressor and send that operating data to the processor. The plurality of peripheral devices may be in communication with the processor. Each of the plurality of peripheral devices may be configured to be controlled by the processor. The plurality of peripheral devices may be configured to operatively control the reciprocating air compressor. Wherein, the processor may be configured to read data from the plurality of sensors and control the plurality of peripheral devices to intelligently extend life of the reciprocating air compressor and reduce energy consumption of the reciprocating air compressor.
One feature of the disclosed intelligent controller may be that it can be configured to calculate an optimum start and stop pressure value to maximize compressor efficiency, and minimize heat buildup without stressing the motor or the air compressor pump based on an entered minimum required pressure.
Another feature of the disclosed intelligent controller may be that it can detect a failure of the check valve and communicate the failure of the check valve and alter operation to protect the reciprocating air compressor from damage.
Another feature of the disclosed intelligent controller may be that it can detect a failure of an exhaust valve and communicate the failure of the exhaust valve.
Another feature of the disclosed intelligent controller may be that it can utilize the operating data of the reciprocating air compressor to diagnose subassembly or component degradation or failure and communicate the component failure to a user, and if required, limiting air compressor operation to prevent a catastrophic failure.
Another feature of the disclosed intelligent controller may be that it can control the reciprocating air compressor to extend the life of the reciprocating air compressor by identifying hazardous operating conditions and warning the user, and if required, limiting compressor function to protect the reciprocating air compressor from the catastrophic failure.
Another feature of the disclosed intelligent controller may be that it can improve efficiency and reliability of the reciprocating air compressor by adjusting control methods via the processor based on contextual decisions to deliver a desired pressure without over pressurizing the reciprocating air compressor or cycling the motor and the air compressor pump excessively.
In select embodiments of the disclosed intelligent controller, the processor may be configured to use a number of networking protocols to obtain a network connection. This network connection may be made via wired or wireless communication. The network connection may be used to communicate the operating data of the reciprocating air compressor from any of the plurality of sensors. In select embodiments, the processor may be configured to make decisions to control the reciprocating air compressor with or without the network connection.
Another feature of the disclosed intelligent controller may be that the operating data from the plurality of sensors can be displayed by the processor to the user through a graphical interface.
In select embodiments of the disclosed intelligent controller, the processor can be configured to communicate with the plurality of sensors and the plurality of peripheral devices via wired communication lines or wireless communication lines.
In select embodiments of the disclosed intelligent controller, the plurality of sensors may include: at least one interstage pressure sensor, each of the at least one interstage pressure sensor is configured to monitor pressure between stages of compression; a first tank pressure sensor configured to monitor pressure of air in a tank; a final discharge pressure sensor configured to monitor pressure after an exhaust valve of a final stage, but before the check valve; the like; and/or combinations thereof. In select optional embodiments, the plurality of sensors may further include: an oil pressure sensor configured to monitor oil pressure; an air intake pressure sensor configured to monitor pressure at an inlet of a first stage; an air intake differential pressure sensor configured to monitor pressure loss across an intake filter; a valve temperature sensor, the valve temperature sensor is configured to measure the surface temperature of the exhaust valve or the intake valve; a regulated pressure sensor positioned after a tank pressure regulator, the regulated pressure sensor is configured to monitor the pressure of air exiting the tank pressure regulator; an oil level sensor being a float type device sensor to monitor the level of oil in the air compressor pump to protect from low oil levels; the like; and/or combinations thereof.
In select embodiments of the disclosed intelligent controller, the plurality of peripheral devices may include: a head unloader valve configured to energize or de-energize head unloaders for unloaded operation; a blowdown valve configured to discharge air between the exhaust valve of the final stage and the check valve going into the tank; the like; and/or combinations thereof. In select optional embodiments, the plurality of peripheral devices may further include: the tank pressure regulator configured to control pressure exiting the tank, the tank pressure regulator is configured to be manually controlled or digitally controlled; a tank drain valve configured to drain condensate from the tank; a tank discharge isolation valve being an electronically controlled valve at a discharge of the tank, the tank discharge isolation valve is configured to isolate a distribution network of piping and hose exiting the tank; a relay being an electronic on-off switch configured to control power to a starter; the like; and/or combinations thereof.
In select embodiments, the disclosed intelligent controller may include a housing. The housing may be configured to house the processor. In select embodiments, the housing may be configured to further house the plurality of sensors and/or the plurality of peripheral devices. In select embodiments, the housing may be sized similar to a conventional pressure switch size. In select embodiments, the housing may include a manifold assembly. The manifold assembly may include an internal passage configured to support multiple ports all connected to the tank. In select embodiments, the multiple ports may connect the processor to a head unloader valve, a gauge, a pressure relief valve, a discharge port, the like, and/or combinations thereof. A threaded connection point may be on a bottom or a side of the housing. The threaded connection point may be a standard pipe thread configured to mount to a pipe nipple on the tank. Wherein, the manifold assembly may be configured to supply air from the tank and to the head unloader valve through a head unloader solenoid valve. In select embodiments, the manifold assembly may include a second passage. The second passage may be connected to a compressor side of the check valve. The second passage may be configured to connect the processor with a pressure transducer and a blowdown valve.
In select embodiments, the disclosed intelligent controller may be powered by a dedicated power supply or from a compressor supply power. Wherein, a switch may incorporate a relay with main power being supplied to the motor through the intelligent controller or may have an electronic signal or a power supply to turn the motor on and off using a magnetic starter.
Another feature of the disclosed intelligent controller may be that it can be configured to detect a faulty check valve on the reciprocating air compressor.
Another feature of the disclosed intelligent controller may be that it can be configured to detect a leaking exhaust valve or a plethora of exhaust valves on the reciprocating air compressor.
Another feature of the disclosed intelligent controller may be that it can be configured to protect the reciprocating air compressor motor from failing prematurely.
Another feature of the disclosed intelligent controller may be that it can be configured to autonomously adjust start and stop pressures on the reciprocating air compressor to reduce energy and heat.
Another feature of the disclosed intelligent controller may be that it can be configured to record a new capacity baseline for a new compressor when it is started for the first time at the factory after being assembled.
Another feature of the disclosed intelligent controller may be that it can be configured to record a current capacity baseline and calculate a current system capacitance for an installation during field commissioning or any time after the reciprocating air compressor is installed in a system.
Another feature of the disclosed intelligent controller may be that it can be configured to identify a catastrophic leak or an excessive demand on the reciprocating air compressor.
Another feature of the disclosed intelligent controller may be that it can be configured to detect a leaking intake valve or a plethora of intake valves between stages on a multi-stage reciprocating air compressor.
Another feature of the disclosed intelligent controller may be that it can be configured to detect a leaking exhaust valve or a plethora of exhaust valves between stages on the multi-stage reciprocating air compressor.
In another aspect, the instant disclosure embraces the disclosed intelligent controller for a reciprocating air compressor in any embodiment and/or combination of embodiments shown and/or described herein.
In another aspect, the instant disclosure embraces a method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor utilizing the disclosed intelligent controller for a reciprocating air compressor in any embodiment and/or combination of embodiments shown and/or described herein. As such, in general, the disclosed method of intelligently extending life of a reciprocating air compressor and reducing energy consumption of the reciprocating air compressor may include the steps of: providing the disclosed intelligent controller for a reciprocating air compressor in any embodiment and/or combination of embodiments shown and/or described herein; installing the intelligent controller on the reciprocating air compressor; reading data from the plurality of sensors; and controlling the plurality of peripheral devices to intelligently extend life of the reciprocating air compressor and reduce energy consumption of the reciprocating air compressor.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of controlling the plurality of peripheral devices to intelligently extend life of the reciprocating air compressor and reduce energy consumption of the reciprocating air compressor may include the steps of: calculating an optimum start and stop pressure value to maximize compressor efficiency, and minimize heat buildup without stressing the motor or the air compressor pump based on an entered minimum required pressure; detecting a failure of the check valve and communicating the failure of the check valve and alter operation to protect the reciprocating air compressor from damage; detecting a failure of an exhaust valve and communicating the failure of the exhaust valve; utilizing the operating data of the reciprocating air compressor to diagnose subassembly or component degradation or failure and communicating the component failure to a user, and if required, limiting air compressor operation to prevent a catastrophic failure; controlling the reciprocating air compressor to extend the life of the reciprocating air compressor by identifying hazardous operating conditions and warning the user, and if required, limiting compressor function to protect the reciprocating air compressor from the catastrophic failure; improving efficiency and reliability of the reciprocating air compressor by adjusting control methods via the processor based on contextual decisions to deliver a desired pressure without over pressurizing the reciprocating air compressor or cycling the motor and the air compressor pump excessively; the like; and/or combinations thereof.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of controlling the plurality of peripheral devices to intelligently extend life of the reciprocating air compressor and reduce energy consumption of the reciprocating air compressor may include the steps of: detecting a faulty check valve on the reciprocating air compressor; detecting a leaking exhaust valve or a plethora of exhaust valves on the reciprocating air compressor; protecting the reciprocating air compressor motor from failing prematurely; autonomously adjust start and stop pressures on the reciprocating air compressor to reduce energy and heat; record a new capacity baseline for a new compressor when it is started for the first time at the factory after being assembled; record a current capacity baseline and calculate a current system capacitance for an installation during field commissioning or any time after the reciprocating air compressor is installed in a system; identify a catastrophic leak or an excessive demand on the reciprocating air compressor; detecting a leaking intake valve or a plethora of intake valves between stages on a multi-stage reciprocating air compressor; detecting a leaking exhaust valve or a plethora of exhaust valves between stages on the multi-stage reciprocating air compressor; testing the head unloader valve and head unloaders; testing the blowdown valve; the like; and/or combinations thereof.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of detecting the faulty check valve on the reciprocating air compressor may include the steps of: stopping or unloading the reciprocating air compressor; opening an electronically controlled valve to exhaust air from the discharge of the air compressor ahead of a check valve; analyzing data from a pressure sensor installed on the line between the air compressor discharge and the check valve, calculate and save time required to reduce pressure in the line to a safe start pressure for the air compressor wherein this data may be used to determine when to initiate the compressor start sequence; closing the electronically controlled valve after a predetermined or calculated period of time; analyzing data from a pressure sensor installed on the line between the air compressor discharge and the check valve to identify air leaking past the check valve; communicating a check valve failure if the analysis determines the check valve is leaking; keeping the electronically controlled valve closed to prevent the compressed air leaking past the check valve from exhausting to the atmosphere saving energy by not wasting stored compressed air; and analyzing data from a pressure sensor installed on the tank circuit to calculate when to initiate a compressor start sequence so the compressor can safely start before pressure decays to a value less than a defined minimum pressure setting. The compressor start sequence may include, but is not limited to, open blowdown valve to exhaust any air that may have leaked past the check valve; signal motor to start after compressor pump discharge pressure is below a defined value; the like, etc. If pressure between the pump and the check valve does not drop below a critical pressure value the motor will not be signaled to start until pressure falls to the required value. This may be done to protect the pump and motor. For a compressor with head unloaders: if the motor was stopped the start sequence is same as above but adds energize head unloaders to reduce start load. After motor start command, head unloaders are de-energized and the blow down valve closed after predetermined time; and if motor was not stopped and the head unloaders were energized with motor running, start sequence opens blowdown valve. After a predetermined time even if pump discharge pressure is above critical pressure the head unloaders are de-energized because momentum of the flywheel will allow the pump to load against full pressure without causing damage, then close the blowdown valve.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of detecting the leaking exhaust valve or the plethora of exhaust valves on the reciprocating air compressor may include the steps of: stopping or unloading the reciprocating air compressor; keeping the blowdown valve (used to evacuate air between the check valve and pump discharge) in a closed state to not evacuate air from a discharge line of the air compressor; analyzing data from a pressure sensor installed on the line between the air compressor discharge and the check valve to identify a leaking exhaust valve; communicating an air compressor exhaust valve failure if the analysis determines one or more exhaust valves are leaking; if pressure decays to a value close to zero or less than the tank pressure this indicates the check valve is holding but the air has leaked past the exhaust valves and out through the crank case vent or intake valves if they are also leaking; evaluating exhaust valve leakage including trending compressor capacity by rate of pressure change with respect to time and also by monitoring discharge temperature, thereby increasing confidence in the failure diagnosis or evaluating severity; and if pressure tracks with the tank pressure, communicating the exhaust valves are holding and working fine.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of protecting the reciprocating air compressor motor from failing prematurely may include the steps of: analyzing data from a pressure sensor while the reciprocating air compressor is loaded to estimate the time the motor will be off after reaching the stop pressure target; analyzing the reciprocating air compressor motor design data, loaded time, possibly pressure, possibly temperature, and possibly motor age to estimate a minimum safe motor off duration; deciding to unload the reciprocating air compressor or stop the motor by comparing the estimated time the motor will be off after reaching the stop pressure target with the calculated minimum safe motor off duration; and deciding to temporarily raise the motor stop pressure setting to extend the calculated off time to protect the motor if the air compressor is not capable of unloading the compressor pump while keeping the motor on.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of autonomously adjusting the start and stop pressures on the reciprocating air compressor to reduce energy and heat may include the steps of: analyzing data from a single or plethora of pressure sensors while the compressor is loaded and off to estimate loaded and off duration as a function of the loaded rate of change; analyzing the change in pressure with respect to time while the reciprocating air compressor is loaded, calculate the stop-unload pressure required to satisfy the minimum threshold loaded time and off time to reliably cycle the reciprocating air compressor; and stopping or unloading the reciprocating air compressor using the calculated pressure value.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of recording the new capacity baseline for the new compressor when it is started for the first time at the factory after being assembled may include the steps of: upon the first startup of the new compressor at the factory, measuring and recording pressure rate of change as part of the initial controller registration and commissioning, wherein this value of pressure rate of change is used for quality verification by the supplier and future performance verification; and as part of the controller commissioning during the initial factory registration, the compressor model information associating the compressor factory capacity rating, tank volume and other factory settings allocated to the model for future control and calculator purposes.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of recording the current capacity baseline and calculate the current system capacitance for the installation during field commissioning or any time after the reciprocating air compressor is installed in the system may include the steps of: in the field, isolating the tank and conducting a performance verification test to compare and quantify compressor performance against the factory new baseline value; and upon field installation startup, measuring and recording running pressure rate of change and off pressure rate of change, wherein the intelligent controller using this information and the factory commissioning data to calculate capacitance of the installation system, wherein this data is used to calculate volume flow rate, leak rate and as a baseline to detect degradation in compressor performance.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of identifying a catastrophic leak or an excessive demand on the reciprocating air compressor may include the steps of: while the reciprocating air compressor is running fully loaded and encounters a negative pressure rate of change, reducing pressure to a defined value below the start pressure and for a calculated period of time the compressor is stopped; if pressure stops dropping or the negative rate of change is less than or equal to the normal leak value or continues to decay to a value close to zero, automatically restarting the reciprocating air compressor; if pressure builds in the system to some defined value above the start pressure, documenting the excessive demand event with start time, duration, and estimated volume flow rate and communicating as an exceeded capacity event warning; if pressure will not recover when the compressor is turned back on, turning off the reciprocating air compressor and communicating a catastrophic leak message, wherein it is determined to be a catastrophic leak because the excessive demand event did not stop after pressure decreased to an unproductive level implying the event was not monitored or intentional; and communicating events along with an estimated volume, time of day and duration thereby helping the compressor owner determine if they can modify their compressed air usage or consider upgrading their compressed air system. This customer message may be related to the excessive demand diagnosis. For the catastrophic leak diagnosis the time and volume estimate may help the customer identify the leak source so they can repair it. Stopping the compressor protects it from potentially running fully loaded at an excessively low pressure and extended time that would cause catastrophic failure of the compressor pump.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of detecting a leaking intake valve or a plethora of intake valves between stages on a multi-stage reciprocating air compressor may include the steps of: analyzing data from a plethora of pressure sensors installed between stages of the multi-stage reciprocating air compressor, wherein a faulty or failing intake valve will cause interstage pressure to increase above an operating baseline value or pressure will increase after the reciprocating air compressor stops or operates in an unloaded state; communicating an air compressor intake valve failure if the analysis determines one or more intake valves are leaking; and communicating the specific stage of the multi-stage reciprocating air compressor intake valve failure if the analysis determines one or more intake valves are leaking.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of detecting a leaking exhaust valve or a plethora of exhaust valves between stages on the multi-stage reciprocating air compressor may include the steps of: analyzing data from a plethora of pressure sensors installed between stages of the multi-stage reciprocating air compressor, wherein a faulty or failing exhaust valve will cause interstage pressure to decrease below an operating baseline value or pressure will decrease after the compressor stops or operates in an unloaded state; communicating an air compressor exhaust valve failure if the analysis determines one or more exhaust valves are leaking; and communicating the specific stage of the multi-stage reciprocating air compressor exhaust valve failure if the analysis determines one or more exhaust valves are leaking.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of testing the head unloader valve and head unloaders may include the steps of: when the controller logic sends a command to energize the head unloader valve, the valve opens and air at pressure is applied to the head unloaders, wherein one of the head unloaders is mounted on each first stage intake valve, and the compressor pump has one or a plethora of intake valves; after the unload command has been sent, pressurizing the head unloaders will hold the first stage intake valves open and the compressor will not be able to compress air and the mass flow of air from the compressor will become zero, wherein: if all of the head unloaders do not function, the compressor output may only be partially reduced, whereby the controller can analyze the change in tank pressure over time and if activating the head unloader circuit does not reduce the calculated output of the compressor, a head unloader fault will be identified and communicated; if the change in capacity output is only reduced but indicates the compressor is still pumping a percentage of air, the compressor motor is turned off using the motor stop control sequence; if the change in pressure is zero or drops over time this indicates a head unloader failure; if energizing the head unloaders does not change the rate of pressure increase over time in the tank, the issue is a head unloader valve failure, wherein if this occurs the compressor will operate using the motor stop/start control method until the head unloader fault has been corrected; and wherein the testing of the head unloader valve and the head unloaders is configured to be manually initiated or executed at some calculated interval or when it is a utilized control mode.
In select embodiments of the disclosed method of intelligently extending life of a reciprocating air compressor and/or reducing energy consumption of the reciprocating air compressor, the step of testing the blowdown valve may include the steps of: manually initiating or autonomously executing the testing of the blowdown valve every time the blowdown valve is commanded to open or close; wherein: if the compressor is running and the motor is turned off where the blowdown valve is signaled/commanded to open and pressure in the line between the check valve and the pump does not drop at all this is an indication that the blowdown valve will not open and a blowdown valve closed valve fault shall be communicated; if the compressor pressure in this line cannot be exhausted the compressor is started using the head unloaders; if the head unloaders are not available the compressor is configured to not initiate a motor start command until the pressure drops to a predetermined acceptable value which is configured to include pressure dropping to that value in the tank; when the compressor is off and the compressor is commanded to start and load, the command is given to close the blowdown valve, wherein: if the pressure ahead of the check valve does not increase to a value greater than or equal to the tank pressure in a predetermined or calculated amount of time, this indicates the blowdown valve is open and all air from the compressor pump is exhausted through the blowdown valve, and a blowdown valve open failure is communicated and the compressor turned off since it cannot charge the tank and will run for no purpose; if the pressure increases ahead of the check valve to a value greater than or equal to the tank pressure but pressure rate of change indicates the compressor is operating under capacity, the next time compressor turns off, the blowdown valve open command will be postponed and a decreasing or no pressure in the line ahead of the check valve will indicate a blowdown valve open valve fault.
The foregoing illustrative summary, as well as other exemplary objectives and/or advantages of the disclosure, and the manner in which the same are accomplished, are further explained within the following detailed description and its accompanying drawings.
The present disclosure will be better understood by reading the Detailed Description with reference to the accompanying drawings, which are not necessarily drawn to scale, and in which like reference numerals denote similar structure and refer to like elements throughout, and in which:
It is to be noted that the drawings presented are intended solely for the purpose of illustration and that they are, therefore, neither desired nor intended to limit the disclosure to any or all of the exact details of construction shown, except insofar as they may be deemed essential to the claimed disclosure.
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One feature of intelligent controller 10 may be that it can be configured to calculate an optimum start and stop pressure value to maximize compressor efficiency and minimize heat buildup without stressing motor 18 or air compressor pump 16 based on an entered minimum required pressure.
Another feature of intelligent controller 10 may be that it can detect a failure of check valve 22 and communicate the failure of check valve 22 and alter operation to protect reciprocating air compressor 12 from damage.
Another feature of intelligent controller 10 may be that it can detect a failure of an exhaust valve (not shown in the Figures) and communicate the failure of the exhaust valve.
Another feature of intelligent controller 10 may be that it can utilize operating data 28 of reciprocating air compressor 12 from sensors 26 to diagnose subassembly or component degradation or failure and communicate the component failure to a user, and if required, limiting air compressor operation to prevent a catastrophic failure.
Another feature of intelligent controller 10 may be that it can control reciprocating air compressor 12 to extend the life of the reciprocating air compressor by identifying hazardous operating conditions and warning the user, and if required, limiting compressor function to protect reciprocating air compressor 12 from the catastrophic failure.
Another feature of intelligent controller 10 may be that it can improve efficiency and reliability of reciprocating air compressor 12 by adjusting control methods via processor 24 based on contextual decisions to deliver a desired pressure without over pressurizing reciprocating air compressor 12 or cycling motor 18 and air compressor pump 16 excessively.
Processor 24 may be included with intelligent controller 10. See
Another feature of intelligent controller 10 may be that operating data 28 from the plurality of sensors 26 can be displayed by processor 24 to the user or operator through graphical interface 38. Graphical interface 38 may be any gauge(s), lights, screen(s), or web or mobile application(s) used to communicate to the user or operator the operating data 28 of reciprocating air compressor 12. As such, data from processor 24 can be displayed to the users through a number of graphical interfaces, including screens, status lights, or by representing data presented via a web or mobile application.
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In select embodiments, intelligent controller 10 may be powered by a dedicated power supply 105 or from a compressor supply power 106. Wherein, switch 107 may incorporate relay 108 with main power being supplied to motor 18 through intelligent controller 10 or may have an electronic signal or a power supply to turn the motor on and off using magnetic starter 109.
Another feature of intelligent controller 10 may be that it can be configured to detect a faulty check valve 22 on reciprocating air compressor 12.
Another feature of intelligent controller 10 may be that it can be configured to detect a leaking exhaust valve or a plethora of exhaust valves on reciprocating air compressor 12.
Another feature of intelligent controller 10 may be that it can be configured to protect reciprocating air compressor motor 18 from failing prematurely.
Another feature of intelligent controller 10 may be that it can be configured to autonomously adjust start and stop pressures on reciprocating air compressor 12 to reduce energy and heat.
Another feature of intelligent controller 10 may be that it can be configured to record a new capacity baseline for a new compressor when it is started for the first time at the factory after being assembled.
Another feature of intelligent controller 10 may be that it can be configured to record a current capacity baseline and calculate a current system capacitance for an installation during field commissioning or any time after reciprocating air compressor 12 is installed in a system.
Another feature of intelligent controller 10 may be that it can be configured to identify a catastrophic leak or an excessive demand on reciprocating air compressor 12.
Another feature of intelligent controller 10 may be that it can be configured to detect a leaking intake valve or a plethora of intake valves between stages on a multi-stage reciprocating air compressor 12.
Another feature of intelligent controller 10 may be that it can be configured to detect a leaking exhaust valve or a plethora of exhaust valves between stages on the multi-stage reciprocating air compressor 12.
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In sum, the disclosed intelligent controller 10 and disclosed method 200 of use thereof are designed and configured to provide a new electronic controller and method for reciprocating air compressors that will extend the life and reduce the energy consumption of such reciprocating air compressors. The disclosed intelligent controller 10 may include unique logic and an electronic control device that has the ability to process input data from connected sensors and external sources. Intelligent controller 10 may have processing capabilities and may be capable of communicating to external sources using wired or wireless methods. Intelligent controller 10 may have output capabilities to control valves, switches, and other devices with an electronic signal. To simplify the installation of intelligent controller 10 on an existing or new reciprocating air compressor 12, intelligent controller 10 and pneumatic inputs (sensors 26) may be incorporated into a single component that is dimensionally similar to a conventional pressure switch (see
In use, as examples, and clearly not limited thereto: by entering a minimum required pressure, intelligent controller 10 can calculate an optimum start and stop pressure value to maximize compressor efficiency, minimize heat build-up without stressing the motor or compressor; when a check valve fails, intelligent controller will detect the failure, communicate the failure and alter operation to protect the compressor from damage; when an exhaust valve fails, intelligent controller 10 can detect the failure, and communicate the failure; the like; and/or combinations thereof.
In the specification and/or figures, typical embodiments of the disclosure have been disclosed. The present disclosure is not limited to such exemplary embodiments. The use of the term “and/or” includes any and all combinations of one or more of the associated listed items. The figures are schematic representations and so are not necessarily drawn to scale. Unless otherwise noted, specific terms have been used in a generic and descriptive sense and not for purposes of limitation.
The foregoing description and drawings comprise illustrative embodiments. Having thus described exemplary embodiments, it should be noted by those skilled in the art that the within disclosures are exemplary only, and that various other alternatives, adaptations, and modifications may be made within the scope of the present disclosure. Merely listing or numbering the steps of a method in a certain order does not constitute any limitation on the order of the steps of that method. Many modifications and other embodiments will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Accordingly, the present disclosure is not limited to the specific embodiments illustrated herein but is limited only by the following claims.
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| 10876487 | Park et al. | Dec 2020 | B2 |
| Number | Date | Country | |
|---|---|---|---|
| 20230417235 A1 | Dec 2023 | US |
