Automatic electric drive full flow clearance stepless adjustment system and method for reciprocating compressor

Abstract

A reciprocating compressor automatic electric drive full flow clearance stepless adjustment system and method, relates to the field of reciprocating compressors. The adjustment system is equipped with electric actuators on the shaft side and cover side of each cylinder of the compressor, and the flow adjustment range is 0% to 100% full flow adjustment, which is much larger than the adjustment range of the current electro-hydraulic servo control; the electric drive replaces the hydraulic drive, cancels the hydraulic oil station and the corresponding hydraulic pipeline, and there is no hydraulic oil leakage and the fire, equipment damage and pollution of the gas in the compressor cylinder that may be caused by it, which minimizes the installation and maintenance costs, and will be one of the best ways to save energy for reciprocating compressors.

Description

Technical Field

[0001] The present invention relates to the field of reciprocating compressors, and in particular to an automatic electric drive full-flow clearance stepless adjustment system and method for reciprocating compressors. Background Art

[0002] Because reciprocating piston compressors are typically designed for maximum operating flow, while the actual operating flow required is often less than the designed flow, many compressors waste energy. Clearance adjustment is an energy-saving method for regulating the flow of reciprocating piston compressors. The operating principle is that the clearance volume within the compressor cylinder is inversely proportional to the flow rate. By changing the clearance volume, the compressor flow rate can be varied. The compressor's main motor shaft power changes almost in direct proportion to the flow rate. This can be simply understood as the clearance volume being inversely proportional to the main motor shaft power.

[0003] Currently, the technology of automatic stepless clearance adjustment system using electro-hydraulic servo control has been applied to reciprocating compressors in the petroleum, chemical and gas industries.

[0004] Electro-hydraulic servo-controlled stepless clearance adjustment devices generally only adjust the air volume on the compressor cylinder head side, with an adjustment range of 60% to 100% of the rated flow rate. They cannot fully regulate the compressor's flow rate. They require a large, sophisticated hydraulic oil station, imposing high requirements for operation and maintenance. Complex hydraulic piping must be configured on-site, making hydraulic oil leakage difficult to avoid. A pipeline rupture can cause fire, equipment damage, and affect compressor operation. Oil leakage from the hydraulic cylinder piston rod of the clearance adjustment actuator can contaminate the air in the compressor cylinder. This system cannot fully meet the requirements of the petroleum, chemical, and gas industries for oil-free lubrication, fire and explosion protection, and long-term safe operation. The high cost also limits its application in small compressors. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention aims to provide a system and method for automatically electrically driving a full-flow clearance stepless adjustment of a reciprocating compressor.

[0006] The technical solution adopted by the present invention is: an automatic electric-driven full-flow clearance stepless adjustment system for a reciprocating compressor, including an adjustable clearance cylinder, an electric actuator and a control system, wherein the adjustable clearance cylinder is mainly composed of a clearance cylinder, a clearance piston, a piston rod and a flange. The technical points are that the electric actuator includes an electric motor, a torque controller, a reduction gear and a transmission locking mechanism, and the transmission locking mechanism is mainly composed of a first thrust bearing installed in a thrust bearing seat, a second thrust bearing installed in a cooling water jacket, a lead screw and a nut. The electric motor is connected to the torque controller, the torque controller is connected to the reduction gear, the reduction gear is connected to the thrust bearing seat, and the thrust bearing seat is connected to the cooling water jacket. The cooling water jacket is connected, and the cooling water jacket is respectively connected to the clearance cylinder and the compressor cylinder through flanges. The reduction gear box is connected to the screw with a thrust plate through a key. The thrust plate is located between the first thrust bearing and the second thrust bearing. The screw is threaded with the nut fixed on the piston rod. One end of the piston rod is connected to the clearance piston installed in the clearance cylinder. The clearance cylinder is also provided with a limit stop to prevent the clearance piston from colliding with the compressor piston. The clearance piston is provided with a guide rod to prevent the clearance piston from rotating. The screw drives the nut to move left and right as the motor rotates, and the clearance piston moves left and right in the clearance cylinder together with the nut, which is used to change the clearance volume of the compressor.

[0007] In the above solution, a heat dissipation fin for reducing the temperature of the clearance cylinder is further provided on the clearance cylinder housing.

[0008] In the above solution, a guide sleeve is further provided outside the clearance piston to prevent the clearance piston from rotating.

[0009] In the above scheme, a sensor sleeve is also connected to the flange, the guide rod is located in the sensor sleeve, and a position sensor is installed on the sensor sleeve. The magnetic ring of the position sensor is installed on the guide rod. The magnetic ring moves with the clearance piston and is used to provide real-time feedback of the position of the clearance piston to the control system.

[0010] In the above solution, a balancing hole is provided on the flange, and the balancing hole is connected to the balancing cavity of the clearance piston. By adjusting the pressure of the balancing cavity, the pressure on both sides of the clearance piston is balanced, so that the power of the clearance adjustment motor is reduced.

[0011] In the above solution, a sealing ring is provided between the clearance piston and the clearance cylinder for isolating the gas on the left and right sides of the clearance piston.

[0012] In the above solution, a first sealing ring for preventing gas in the balance chamber from leaking toward the cooling water jacket and a second sealing ring for preventing gas passing through the first sealing ring from leaking toward the cooling water jacket are provided between the piston rod and the flange.

[0013] In the above solution, a leakage detection port is provided between the first sealing ring and the second sealing ring;

[0014] In the above solution, a leak detection sensor is installed at the leak detection port, and a control system connected to the leak detection sensor determines whether to issue an alarm or an interlock control shutdown signal based on the received detection signal.

[0015] A method for automatically adjusting the full-flow clearance of a reciprocating compressor by electric drive, comprising the following adjustment steps:

[0016] The compressor data collection step is used to collect the compressor control variables and the inlet and exhaust pressures at each level, the inlet and exhaust temperatures at each level, and the compressor flow rate during actual operation of the compressor, and transmit them to the control system;

[0017] The step of collecting clearance piston data is used to detect the actual clearance piston position signal in the electric actuator in real time and transmit it to the control system;

[0018] The step of controlling the electric actuator is used to select a signal from the received signals as a control variable. If the control system determines that the load needs to be increased, the control system issues a forward rotation command for the motor, connects the power supply, the motor rotates forward, the clearance piston moves to one side, the clearance is reduced, and the air volume of the compressor increases;

[0019] If the control system determines that the load needs to be reduced, the control system issues a motor reversal command, reverses the power supply, the motor reverses, the clearance piston moves to the other side, the clearance increases, and the compressor gas volume decreases;

[0020] When the control system determines that the load remains unchanged, the control system issues a motor stop command, disconnects the power supply, the motor stops, the transmission locking mechanism locks, the clearance piston stops, the clearance remains unchanged, and the compressor gas volume remains unchanged.

[0021] The beneficial effects of the present invention are as follows: the automatic electric-driven full-flow clearance stepless adjustment system and adjustment method for a reciprocating compressor has electric actuators installed on the shaft side and cover side of each cylinder of the compressor, and the flow adjustment range is 0% to 100% full-flow adjustment, which is much larger than the adjustment range of the current electro-hydraulic servo control; the electric drive replaces the hydraulic drive, eliminates the hydraulic oil station and the corresponding hydraulic pipelines, and there is no hydraulic oil leakage and the fire, equipment damage and pollution to the gas in the compressor cylinder that may be caused thereby, thereby minimizing installation and maintenance costs, which will be one of the best ways to save energy for reciprocating compressors. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 Schematic diagram of the structure of an electric mechanism with a guide rod in an embodiment of the present invention;

[0024] Figure 2 This is an electric actuator with an eccentric structure in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the installation position of the electric actuator on the compressor in an embodiment of the present invention;

[0026] Figure 4 This is a control principle diagram of the flow clearance stepless adjustment control system in an embodiment of the present invention;

[0027] The serial numbers in the figure are explained as follows: 1 electric motor, 2 torque controller, 3 reduction gearbox, 4 thrust bearing seat, 5 thrust bearing, 6 cooling water jacket, 7 lead screw, 8 leakage detection port, 9 flange, 10 balancing hole, 11 nut, 12 sealing ring, 13 piston rod, 14 limit stop, 15 clearance piston, 16 sealing ring, 17 clearance cylinder, 18 cooling fin, 19 guide rod, 20 magnetic ring, 21 cooling water port, 22 sensor sleeve, 23 thrust plate, 24 key, 25 position sensor, 26 cover-side electric actuator, 27 compressor cylinder, 28 shaft-side electric actuator. DETAILED DESCRIPTION

[0028] To make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the following Figures 1 to 4 The present invention is further described in detail with reference to the accompanying drawings and specific embodiments.

[0029] Example 1:

[0030] The reciprocating compressor automatic electric drive full flow clearance stepless adjustment system used in this embodiment is as follows: Figure 1As shown, the system comprises an adjustable clearance cylinder, an electric actuator, and a control system. The adjustable clearance cylinder primarily consists of a clearance cylinder barrel 17, a clearance piston 15, a piston rod 13, and a flange 9. The electric actuator comprises a motor 1, a torque controller 2, a reduction gearbox 3, and a transmission locking mechanism. The motor 1 can be any of a conventional asynchronous motor, a DC motor, or a stepper motor. Unlike conventional systems that use high-cost stepper motors or complex and leak-prone hydraulic systems, the electric actuator can be operated manually on-site. The torque controller and reduction gearbox form a torque control and amplification mechanism, controlling the low torque output by the motor 1 and protecting it from overload. The reduction gearbox also amplifies the torque. The transmission locking mechanism primarily consists of a thrust bearing 5 mounted in a thrust bearing housing 4, a lead screw 6 mounted in a cooling water jacket, and a nut 10. The control system utilizes a conventional industrial control system and can be any of a programmable logic controller (PLC), a distributed control system (DCS), and a safety instrumented system (SIS). The connection structure of the components that make up the stepless clearance adjustment system in this embodiment is as follows:

[0031] The motor 1 is connected to the torque controller 2, the torque controller 2 is connected to the reduction gearbox 3, the reduction gearbox 3 is connected to the thrust bearing seat 4, the thrust bearing seat 4 is connected to the cooling water jacket 6 with a cooling water port 21, the cooling water jacket 6 is connected to the clearance cylinder 17 and the compressor cylinder 27 respectively through the flange 9, the reduction gearbox 3 is connected to the screw 7 with the thrust plate 23 through the key 24, wherein the thrust plate 23 is located between the two thrust bearings 5, the screw 7 is threadedly connected to the nut 11 fixed on the piston rod 13, and one end of the piston rod 13 is connected to the clearance piston 15 installed in the clearance cylinder 17. The clearance piston 15 and the piston rod 13 in this embodiment adopt a concentric matching structure. A limit stop 14 is also provided on the clearance cylinder 17 to prevent the clearance piston 15 from colliding with the compressor piston. A guide rod 19 is installed on the clearance piston 15 to prevent the clearance piston 15 from rotating. The screw 7 rotates with the motor 1 to drive the nut 11 to move left and right, and the clearance piston 15 moves left and right in the clearance cylinder 17 together with the nut 11 to change the clearance volume of the compressor.

[0032] The flange 9 is fixedly connected to the sensor sleeve 22 by bolts, and a position sensor 25 is installed on the sensor sleeve 22. The guide rod 19 is located in the sensor sleeve 22. The magnetic ring 20 of the position sensor 25 is installed on the guide rod 19. The magnetic ring 20 moves with the clearance piston 15 and is used to provide real-time feedback of the position of the clearance piston 15 to the control system (not shown in the figure).

[0033] A balancing hole 10 is provided on the flange 9 and communicates with the balancing chamber of the clearance piston 15. Changing the connection between the balancing hole and the inlet, outlet, or venting system of a compressor stage can change the pressure in the balancing chamber, effectively balancing the pressure on both sides of the clearance piston 15 and reducing the power of the clearance adjustment motor 1. A sealing ring 16 is provided between the clearance piston 15 and the clearance cylinder 17 to isolate the gas on either side of the clearance piston 15. A sealing ring 12 is provided between the piston rod 13 and the flange 9 to prevent gas in the balancing chamber from leaking toward the cooling water jacket 6, and a second sealing ring is provided to prevent gas from leaking through the sealing ring 12 into the cooling water jacket 6. A leak detection port 8 is provided between the first and second sealing rings of the sealing ring 12. A leak detection sensor is installed in the leak detection port 8. A control system connected to the leak detection sensor determines whether to issue an alarm or interlock control shutdown signal based on the detection signal received. Heat dissipation fins 18 are also provided on the housing of the clearance cylinder 17 to reduce the temperature of the clearance cylinder 17.

[0034] The stepless clearance adjustment system in this embodiment can use explosion-proof components according to the application scenario, can meet the requirements of explosion-proof Ⅱ C zone at the application site, and can cover all reciprocating piston compressor equipment with power supply at the application site.

[0035] In this embodiment, electric actuators are installed on the shaft side and cover side of each cylinder of the compressor. The flow adjustment range is 0% to 100% full flow adjustment, and the adjustment range is much larger than the adjustment range of the current electro-hydraulic servo control. The electric drive replaces the hydraulic drive, eliminates the hydraulic oil station and the corresponding hydraulic pipelines, and there is no hydraulic oil leakage and the fire, equipment damage and gas pollution in the compressor cylinder that may be caused by it. The installation and maintenance costs are minimized, and it will be the safest and most reliable stepless clearance adjustment system. Among them, the cover-side electric actuator 26 is usually installed at the compressor cylinder head, on the axis of the compressor cylinder 27, and the shaft-side electric actuator 28 is usually installed at the compressor valve hole and airway, in the radial direction of the compressor cylinder 27. The clearance cylinder barrel 17 of the electric actuator is directly connected to the compressor cylinder 27, such as Figure 2 shown.

[0036] Example 2:

[0037] The difference between this embodiment and embodiment 1 is that a cooling water jacket is used instead of the heat dissipation fins 18 to be sleeved on the outer surface of the clearance cylinder 17 .

[0038] Example 3:

[0039] The difference between this embodiment and embodiment 1 is that a cooling system is provided outside the flange, and the cooling system may adopt air-cooled fins or a liquid cooling cavity, such as a cooling water jacket as the liquid cooling cavity.

[0040] Example 4:

[0041] The difference between this embodiment and embodiment 1 is that an eccentric electric actuator is used instead of the concentric matching structure of the clearance piston and piston rod. This method can prevent the clearance piston 15 from rotating. The specific structure is: the guide rod 19 is eliminated, and the position sensor 25 is directly installed on the reduction box 3 in the torque control and amplification mechanism. The other structures are similar to those of embodiment 1 and will not be repeated here. Figure 2 shown.

[0042] Example 5:

[0043] In this embodiment, the full-flow clearance stepless adjustment method is adopted. The compressor control variables and the data such as the intake and exhaust pressures at each level, the intake and exhaust temperatures at each level, the compressor flow and the actuator leakage during actual operation of the compressor are all collected by conventional transmitters and transmitted to the control system.

[0044] The position of the clearance piston is usually collected by a position sensor. The position sensor can be a magnetostrictive or encoder position sensor. The electric actuator with a guide rod is suitable for a magnetostrictive position sensor, and the electric actuator with an eccentric structure is suitable for an encoder. The position sensor can detect the actual position of the clearance piston in the electric actuator in real time and transmit it to the control system.

[0045] The control system calculates based on the compressor control variables, the actual operating parameters of the compressor collected, and the actual position parameters returned by the position sensor, and issues correction instructions to control the operation or stop of the electric actuator.

[0046] The control system sends out an alarm or interlock control signal according to the leakage amount detected by the leakage sensor.

[0047] For example, when the compressor's required flow rate is used as the control variable data, the compressor's required flow rate is converted to a load value between 0 and 100%. At this time, the real-time position signal shows that the compressor load is a certain value G, and the compressor's required flow rate is another value H. When H>G, that is, the demanded flow rate is greater than the actual flow rate, the system controls the motor to rotate forward; when H=G, that is, the demanded flow rate is equal to the actual flow rate, the system controls the motor to maintain the locked position; when H<G, that is, the demanded flow rate is less than the actual flow rate, the system controls the motor to rotate reversely.

[0048] For example, when the compressor inlet pressure is used as the control variable data, the actual compressor inlet pressure data is compared with the required inlet pressure data. In this case, the actual inlet pressure is G and the process demand is H. When H>G, that is, the demand value is greater than the actual value, the compressor is required to appropriately reduce the flow rate to increase the inlet pressure, and the system controls the motor to reverse. When H=G, that is, the demand value is equal to the actual value, the system controls the motor to maintain the locked position. When H<G, that is, the demand value is less than the actual value, the compressor is required to appropriately increase the flow rate to reduce the inlet pressure, and the system controls the motor to rotate forward.

[0049] The required flow rate of the compressor is used as the control variable data, and the required flow rate of the compressor is converted into a load value of 0-100%. At this time, the real-time position signal shows that the compressor load is a certain value G, and the required flow rate of the compressor is another value H. When H>G, that is, the demand is greater than the actual amount, the system controls the motor to rotate forward; when H=G, that is, the demand is equal to the actual amount, the system controls the motor to keep the lock position; when H<G, that is, the demand is less than the actual amount, the system controls the motor to reverse.

[0050] For example, when the compressor inlet pressure is used as the control variable data, the actual compressor inlet pressure data is compared with the required inlet pressure data. In this case, the actual inlet pressure is G and the process demand is H. When H>G, that is, the demand value is greater than the actual value, the compressor is required to appropriately reduce the flow rate to increase the inlet pressure, and the system controls the motor to reverse. When H=G, that is, the demand value is equal to the actual value, the system controls the motor to maintain the locked position. When H<G, that is, the demand value is less than the actual value, the compressor is required to appropriately increase the flow rate to reduce the inlet pressure, and the system controls the motor to rotate forward.

[0051] Since the volumetric efficiency of the compressor clearance adjustment control method is very low when running at low load, it may cause excessive temperature rise of the cylinder temperature and exhaust temperature, vibration or breakage of the valve plate, and even damage to the compressor cylinder. Moreover, there are more safety hazards when the compressor is overloaded. Therefore, in order to achieve full flow 0-100% load adjustment operation of the compressor within the safe operating range, it is necessary to monitor the operating data in real time and control the compressor unit in real time.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An automatic electric drive full-flow clearance stepless adjustment system for a reciprocating compressor, comprising an adjustable clearance cylinder, an electric actuator and a control system, wherein the adjustable clearance cylinder is mainly composed of a clearance cylinder barrel, a clearance piston, a piston rod and a flange, and is characterized in that: The electric actuator comprises a motor, a torque controller, a reduction gearbox and a transmission locking mechanism, wherein the transmission locking mechanism is mainly composed of a first thrust bearing installed in a thrust bearing seat, a second thrust bearing installed in a cooling water jacket, a lead screw and a nut, wherein the motor is connected to the torque controller, the torque controller is connected to the reduction gearbox, the reduction gearbox is connected to the thrust bearing seat, the thrust bearing seat is connected to the cooling water jacket, the cooling water jacket is respectively connected to the clearance cylinder and the compressor cylinder through flanges, the output shaft of the reduction gearbox is connected to the lead screw with a thrust plate through a key, the thrust plate is located between the first thrust bearing and the second thrust bearing, the lead screw is screwed to the nut fixed on the piston rod, one end of the piston rod is connected to the clearance piston installed in the clearance cylinder, a limit stop is also provided on the clearance cylinder to prevent the clearance piston from colliding with the compressor piston, a guide rod is installed on the clearance piston to prevent the clearance piston from rotating, the lead screw drives the nut to move left and right as the motor rotates, and the clearance piston moves left and right in the clearance cylinder together with the nut, so as to change the clearance volume of the compressor; The clearance cylinder housing is also provided with a heat dissipation fin for reducing the clearance cylinder temperature; A guide sleeve is also provided outside the clearance piston to prevent the clearance piston from rotating. A sensor sleeve is also connected to the flange, a guide rod is located in the sensor sleeve, a position sensor is installed on the sensor sleeve, a magnetic ring of the position sensor is installed on the guide rod, the magnetic ring moves with the clearance piston, and is used to provide real-time feedback of the position of the clearance piston to the control system; A balancing hole is provided on the flange, and the balancing hole is connected with the balancing cavity of the clearance piston. The pressure on both sides of the clearance piston is balanced by adjusting the pressure of the balancing cavity, so that the power of the clearance adjustment motor is reduced; A sealing ring is provided between the clearance piston and the clearance cylinder for isolating the gas on the left and right sides of the clearance piston; A first sealing ring for preventing the gas in the balance chamber from leaking toward the cooling water jacket and a second sealing ring for preventing the gas from leaking toward the cooling water jacket through the first sealing ring are provided between the piston rod and the flange; A leak detection port is provided between the first sealing ring and the first sealing ring; Install a leak detection sensor in the leak detection port, and the control system connected to the leak detection sensor determines whether to issue an alarm or interlock control shutdown signal based on the received detection signal; Electric actuators are installed on the shaft side and cover side of each cylinder of the compressor. The cover-side electric actuator is usually installed on the compressor cylinder head, on the axis of the compressor cylinder. The shaft-side electric actuator is usually installed on the compressor valve hole and airway, in the radial direction of the compressor cylinder. The clearance cylinder barrel of the electric actuator is directly connected to the compressor cylinder.

2. A method for automatic electric drive full flow clearance stepless adjustment of a reciprocating compressor, implemented by the adjustment system according to claim 1, characterized in that: The adjustment steps include: The step of collecting compressor data is used to collect compressor control variables and various levels of inlet and exhaust pressures, various levels of inlet and exhaust temperatures, and compressor flow rate during actual operation of the compressor, and transmit them to the control system; The step of collecting clearance piston data is used to detect the position signal of the actual clearance piston in the electric actuator in real time and transmit it to the control system; The step of controlling the electric actuator is used to select a certain signal from the received signals as a control variable. If the control system determines that the load needs to be increased, the control system issues a motor forward rotation instruction, connects the power supply, the motor rotates forward, the clearance piston moves to one side, the clearance decreases, and the compressor gas volume increases; If the control system determines that the load needs to be reduced, the control system issues a motor reversal command, connects the power supply in the reverse direction, the motor reverses, the clearance piston moves to the other side, the clearance increases, and the compressor gas volume decreases; When the control system determines that the load remains unchanged, the control system issues a motor stop command, disconnects the power supply, the motor stops, the transmission locking mechanism locks, the clearance piston stops moving, the clearance remains unchanged, and the compressor gas volume remains unchanged.

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