Low-pressure and low-speed operation mode control method for electric drive pipeline centrifugal compressor

Abstract

The invention belongs to the field of compressor operation control, and particularly relates to a low-pressure and low-speed operation mode control method for an electric drive pipeline centrifugal compressor. According to the method, a control system controls a unit to execute a start-up process, so that a centrifugal compressor starts to work, the unit is warmed up until a motor reaches the minimum working rotating speed, and the working duration of the motor reaches the preset warming-up duration; and then, the unit sequentially executes a shutdown process and an emptying process, and control is ended. Based on the low-pressure low-speed quick start condition, the control method capable of realizing low-pressure low-speed quick start is provided, the process valve start time sequence is completed, the non-purging quick start function is achieved, and the purposes of safe and quick response, energy conservation and consumption reduction of a compressor unit are achieved.

Description

Technical Field

[0001] The present invention relates to a compressor operation control method, and in particular to a low-pressure and low-speed operation mode control method for an electric-driven pipeline centrifugal compressor. Background Art

[0002] As the most critical boosting equipment in the long-distance natural gas pipeline network, the electric-driven pipeline centrifugal compressor plays a core role in transporting natural gas through the pipeline network.

[0003] The main way to transport natural gas is to build a compressor station every 200 kilometers or so during pipeline transportation, and transport the natural gas to the downstream by pressurizing it. Each natural gas compressor station will have at least two sets of compressor units arranged in parallel. The electric-driven pipeline centrifugal compressor of the compressor station needs to be warmed up according to maintenance and operation requirements. However, the warm-up operation of the unit will cause a large amount of natural gas to be vented; at the same time, from the perspective of the unit's rapid response to the pipeline network, there are certain defects.

[0004] Typical systems of existing electric drive pipeline centrifugal compressors are as follows: Figure 1 As shown, the main equipment includes a centrifugal compressor 1, a gear box, a motor 3 (on which a pneumatic valve of a motor positive pressure ventilation system is arranged), a frequency converter 4, a lubricating oil station 5, a dry gas sealing system 6 (on which a dry gas sealing inlet valve is arranged), a compressor control system UCP7, a control system (including a control center MCC9 and a compressor control system UCP7), a UPS power supply 9, two cooling fans 301 and 304, two lifting oil pumps 306 and 307, a main oil pump 501, a standby oil pump 502, an electric heater 503, valves (including external Sealing gas shut-off valve 12, inlet shut-off valve 13, loading valve 14, anti-surge valve 15, emergency vent valve 16, outlet shut-off valve 17, etc.), pipelines, lubricating oil station air cooler 11, motor external water cooling system 20, couplings, etc., its working principle is: the control system controls the speed of motor 3 through inverter 4, motor 3 is connected to centrifugal compressor 1 through coupling, so that the speed of centrifugal compressor 1 is controlled by motor 3, and finally the pressure of natural gas input into the process air inlet is pressurized to the required pressure through centrifugal compressor 1 and discharged through the process exhaust port.

[0005] The existing electric-driven pipeline centrifugal compressor unit starts up by speeding up the centrifugal compressor to the rated speed, which takes a long time and is not conducive to rapid response. Especially when the unit needs to be started up and pressurized urgently after an unexpected shutdown, it cannot meet the rapid response startup requirements of the pipeline network. Summary of the invention

[0006] The purpose of the present invention is to solve the technical problem that the existing electric-driven pipeline centrifugal compressor unit accelerates the centrifugal compressor to the rated speed, which takes a long time to start, is not conducive to rapid response, especially when the unit needs to be started and pressurized urgently after an unexpected shutdown, and cannot meet the technical problem of rapid response startup requirements of the pipeline network. A method for controlling the low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor is provided.

[0007] The startup of electric-driven pipeline centrifugal compressors has always followed a process that requires purging.

[0008] 1. From the perspective of the unit's rapid response to the pipeline network:

[0009] Taking a certain compressor station as an example, it takes 35 minutes to start the machine from the issuance of the start command to reaching the minimum speed, of which 10 minutes are spent on purge, accounting for 28.5% of the time. This is not conducive to rapid response, especially when the machine needs to be started urgently for pressurization after an unexpected shutdown of the unit.

[0010] 2. From the perspective of compressor protection:

[0011] In the initial stage of production, purging is necessary due to the dirtiness of the newly built pipelines and the retention of nitrogen. After normal production and operation, purging is no longer necessary (purging is still required after cleaning and transformation).

[0012] 3. From the perspective of explosion mechanism:

[0013] Direct air intake without displacement, the gas air content in the auxiliary pipelines inside the compressor inlet and outlet ball valves is controlled below 10% (natural gas is calculated at 1Mpa), that is, the natural gas content is always above 90%, far less than the explosion limit range of natural gas of 5%-15%, so there is no safety problem.

[0014] 4. From the perspective of energy saving and consumption reduction:

[0015] On the one hand, each 10-minute purge will waste about 500 cubic meters of natural gas, and the compressor station will have multiple sets of electric-driven pipeline centrifugal compressors.

[0016] At present, the low-pressure and low-speed operation of electric-driven pipeline centrifugal compressors has the promotion significance of energy saving and consumption reduction in domestic pipeline compression stations. Based on an average saving of 500 cubic meters per unit, the country can reduce the discharge of tens of thousands of cubic meters of natural gas throughout the year, with obvious economic benefits.

[0017] To achieve the above purpose, the technical solution adopted by the present invention is:

[0018] A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor is characterized in that it comprises the following steps:

[0019] Step 1: Detect whether the low-pressure warm-up start button is pressed by the control system. If yes, execute step 2; if not, continue to wait until it is detected that the low-pressure warm-up start button is pressed;

[0020] Step 2: Open the pneumatic valve of the motor positive pressure ventilation system and the external sealing gas cut-off valve through the control system, and start the electric heater of the lubricating oil station;

[0021] Step 3: Determine whether the start-up conditions are met through the control system. If yes, execute step 4; if not, perform manual adjustment until the start-up conditions are met;

[0022] Step 4: Control the unit to execute the startup process through the control system, so that the centrifugal compressor starts to work, warms up the unit, and determines whether the motor of the unit reaches the minimum operating speed. If so, execute step 5; if not, continue to wait until the motor reaches the minimum operating speed;

[0023] Step 5: Determine through the control system whether the working time of the motor at the minimum working speed reaches the preset warm-up time. If so, execute step 6; if not, continue to wait until the preset warm-up time is reached;

[0024] Step 6: Control the unit to execute the shutdown process through the control system, and determine whether the unit is shut down. If so, execute step 7; if not, continue to wait until the unit is shut down;

[0025] Step 7: Control the unit to execute the venting process through the control system, and after the venting process is completed, close the pneumatic valve of the motor positive pressure ventilation system, the external sealing gas shut-off valve and the lubricating oil station electric heater to end the control.

[0026] Further, in step 3, the starting conditions specifically include:

[0027] The temperature of the lubricating oil station is normal;

[0028] The unit is stopped without interlocking;

[0029] Parking memory reset;

[0030] UPS power supply has no fault alarm;

[0031] The electric turning gear is engaged.

[0032] Furthermore, in step 4, the startup process is specifically as follows:

[0033] Q1. Start the motor external water cooling system;

[0034] Q2. Stop the lubricating oil pump; the lubricating oil pump includes a main oil pump and a standby oil pump;

[0035] Q3. Open the shutters of the air cooler of the lubricating oil station;

[0036] Q4. Close the shutdown drain valve of the lubricating oil station air cooler;

[0037] Q5. Test the main oil pump;

[0038] Q6. Test the standby oil pump;

[0039] Q7. Start the main oil pump;

[0040] Q8. Start the jacking oil pump and the jacking oil pump;

[0041] Q9. Start the motor cooling fan and the motor cooling fan;

[0042] Q10. Open the dry gas seal inlet valve;

[0043] Q11, open the inlet valve; the inlet valve includes an inlet cut-off valve and a loading valve;

[0044] Q12. Open the anti-surge valve and keep it fully open;

[0045] Q13. Open the emergency vent valve;

[0046] Q14. Close the emergency vent valve;

[0047] Q15, centrifugal compressor is charged to the designed low pressure value;

[0048] Q16. Close the inlet cut-off valve and loading valve;

[0049] Q17. Keep the inlet shut-off valve and loading valve closed, the outlet shut-off valve closed, and the anti-surge valve fully open;

[0050] Q18, inverter closing;

[0051] Q19, inverter start;

[0052] Q20, the inverter controls the motor to start working;

[0053] The minimum operating speed is 1000rpm-1100rpm.

[0054] Furthermore, in step 4, the minimum operating speed is 1044 rpm.

[0055] Furthermore, in step 5, the preset warm-up time is 10 minutes to 20 minutes.

[0056] Furthermore, the preset warm-up time is 15 minutes.

[0057] Furthermore, in step 6, the shutdown process is specifically as follows:

[0058] T1. The control system controls the motor to slow down through the frequency converter. When the motor speed drops to the preset speed, the frequency converter is opened.

[0059] T2, the control system controls the motor external water cooling system to stop working;

[0060] T3. The control system controls the motor to stop working through the frequency converter, completing the unit shutdown.

[0061] Furthermore, in step T1, the preset rotation speed is 448 rpm.

[0062] Further, in step 7, the venting process is specifically as follows:

[0063] F1. The control system detects the fully closed state of the inlet valve, the fully closed state of the outlet cut-off valve, and the fully open state of the anti-surge valve;

[0064] F2. The control system opens the emergency drain valve;

[0065] F3. After the control system detects that the inlet pressure and outlet pressure have reached the design pressure, the venting process is completed.

[0066] Furthermore, in step F3, the design pressure is 2.0 MPa.

[0067] The beneficial effects of the present invention are:

[0068] The present invention is based on the low-pressure, low-speed and rapid start-up situation, proposes a control method for low-pressure, low-speed and rapid start-up, completes the process valve start-up sequence, realizes the non-purge rapid start-up function, and achieves the purpose of safe and rapid response of the compressor unit and energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a structural schematic diagram of an existing electric-driven pipeline centrifugal compressor.

[0070] The reference numerals in the figures are described as follows:

[0071] 1- centrifugal compressor, 3- motor, 4- inverter, 5- lubricating oil station, 6- dry gas sealing system, 7- compressor control system UCP, 8- motor control center MCC, 9- UPS power supply, 301- cooling fan, 304- cooling fan, 306- lifting oil pump, 307- lifting oil pump, 501- main oil pump, 502- standby oil pump, 503- electric heater, 12- external sealing gas shut-off valve, 13- inlet shut-off valve, 14- loading valve, 15- anti-surge valve, 16- emergency vent valve, 17- outlet shut-off valve, 11- lubricating oil station air cooler, 20- motor external water cooling system. DETAILED DESCRIPTION

[0072] In order to make the purpose, advantages and features of the present invention more clear, the following is a further detailed description of a low-pressure and low-speed operation mode control method of an electric-driven pipeline centrifugal compressor proposed by the present invention in combination with the accompanying drawings and specific embodiments. According to the following specific implementation methods, the advantages and features of the present invention will be more clear.

[0073] The present embodiment provides a method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor, specifically comprising the following steps:

[0074] Step 1. According to the warm-up operation requirements of the electric-driven pipeline centrifugal compressor unit (hereinafter referred to as the unit), the operator presses the start button on the HMI (human-machine interaction panel) to activate the unit. The control system detects the state of the start button in real time and determines whether the start button is pressed. If so, execute step 2; if not, continue to wait until it is determined that the start button is pressed.

[0075] Step 2: Open the pneumatic valve of the motor positive pressure ventilation system through the control system, open the external sealing gas cut-off valve 12, and start the lubricating oil station electric heater 503 to start the circulation of the lubricating oil system.

[0076] Step 3: Determine whether the start-up conditions are met through the control system. If so, execute step 3; if not, manual adjustment is required until the control system determines that the start-up conditions are met.

[0077] Specifically, the starting conditions in this embodiment include: 1] the temperature of the lubricating oil station 5 is normal; 2] the unit is parked without interlocking; 3] the parking memory is reset; 4] the UPS power supply 9 has no fault alarm; 5] the electric crank is engaged.

[0078] Step 4, start the startup process through the control system, so that the centrifugal compressor 1 starts to work to warm up the unit, and determine whether the speed of the motor 3 in the unit reaches the preset minimum operating speed. If so, execute step 5; if not, continue to wait until the preset minimum operating speed is reached; according to the working requirements of the centrifugal compressor 1, its minimum operating speed is generally in the range of 1000rpm-1100rpm. In this embodiment, the preferred minimum operating speed is 1044rpm.

[0079] Specifically, the startup process in this embodiment includes the following contents:

[0080] Q1, start the motor external water cooling system 20;

[0081] Q2. Stop the lubricating oil pump; the lubricating oil pump here refers to the main oil pump 501 and the standby oil pump 502;

[0082] Q3. Open the shutters of the lubricating oil station air cooler 11;

[0083] Q4. Close the shutdown drain valve of the lubricating oil station air cooler 11;

[0084] Q5. Test the main oil pump 501;

[0085] Q6. Test the standby oil pump 502;

[0086] Q7, start the main oil pump 501;

[0087] Q8, start the jacking oil pump 306 and the jacking oil pump 307;

[0088] Q9, start the motor cooling fan 301 and the motor cooling fan 304;

[0089] Q10, open the dry gas seal inlet valve ( Figure 1 not shown);

[0090] Q11, open the inlet valve; the inlet valve here refers to the inlet cut-off valve 13 and the loading valve 14;

[0091] Q12, open the anti-surge valve 15 and keep it fully open;

[0092] Q13. Open the emergency drain valve 16;

[0093] Q14. Close the emergency vent valve 16;

[0094] Q15, centrifugal compressor 1 is pressurized to the designed low pressure value;

[0095] Q16, close the inlet loading valve 13;

[0096] Q17, keep the inlet valve closed, the outlet cut-off valve 17 closed, and the anti-surge valve 15 fully open;

[0097] Q18, inverter 4 is closed;

[0098] Q19, inverter 4 starts;

[0099] Q20, inverter 4 controls motor 3 to start.

[0100] Step 5, the control system determines whether the working time of the motor 3 at the minimum working speed reaches the preset warm-up time. The general warm-up time is 10min-20min. In this embodiment, the preferred warm-up time is 15min; if so, execute step 6; if not, continue to wait until the control system determines that the working time of the motor 3 reaches the preset warm-up time.

[0101] Step 6: The control system controls the unit to execute the shutdown process and determines whether the unit is shut down. If so, execute step 7; if not, continue to wait until the unit is shut down;

[0102] Specifically, the shutdown process in this embodiment includes the following contents:

[0103] T1, the control system controls the motor 3 to decelerate. When the speed of the motor 3 drops to a preset speed, the control system controls the inverter 4 to open. In this embodiment, the speed is preset to 448 rpm.

[0104] T2, the control system controls the motor external water cooling system 20 to stop working;

[0105] T3, the control system controls the motor 3 to stop working, thereby completing the shutdown.

[0106] Step 7, the control system controls the unit to execute the venting process, and after the venting process is completed, closes the pneumatic valve of the motor positive pressure ventilation system, closes the external sealing gas shut-off valve 12, and closes the lubricating oil station electric heater 503 to stop the circulation of the lubricating oil system.

[0107] Specifically, the venting process in this embodiment includes the following contents:

[0108] F1, the control system detects the fully closed state of the loading valve 14, the fully closed state of the inlet cut-off valve 13, the fully closed state of the outlet cut-off valve 17, and the fully open state of the anti-surge valve 15;

[0109] F2. Open the emergency drain valve 16;

[0110] F3. After the control system detects that the inlet pressure and the outlet pressure (i.e., the pressure at the inlet valve and the outlet shut-off valve 17) reach the design pressure, specifically, the design pressure in this embodiment is 2.0 MPa, the venting process is completed and the control ends.

Claims

1. A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor, characterized in that: The following steps are involved: Step 1: Detect whether the low-pressure warm-up start button is pressed by the control system. If yes, execute step 2; if not, continue to wait until it is detected that the low-pressure warm-up start button is pressed; Step 2: Open the pneumatic valve of the motor positive pressure ventilation system and the external sealing gas cut-off valve (12) through the control system, and start the lubricating oil station electric heater (503); Step 3: Determine whether the start-up conditions are met through the control system. If yes, execute step 4; if not, perform manual adjustment until the start-up conditions are met; Step 4: Control the electric drive pipeline centrifugal compressor unit through the control system to execute the startup process, so that the centrifugal compressor (1) starts to work, warms up the unit, and determines whether the motor (3) of the unit has reached the minimum operating speed. If so, execute step 5; if not, continue to wait until the motor reaches the minimum operating speed; Step 5: determining, by the control system, whether the working time of the motor (3) at the minimum working speed reaches a preset warm-up time; if so, executing step 6; if not, continuing to wait until the preset warm-up time is reached; Step 6: Control the unit to execute the shutdown process through the control system, and determine whether the unit is shut down. If so, execute step 7; if not, continue to wait until the unit is shut down; Step 7, control the unit to execute the venting process through the control system, and after the venting process is completed, close the pneumatic valve of the motor positive pressure ventilation system, the external sealing gas shut-off valve (12) and the lubricating oil station electric heater (503), and end the control.

2. A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor according to claim 1, characterized in that: In step 3, the starting conditions specifically include: The temperature of the lubricating oil station (5) is normal; The unit is stopped without interlocking; Parking memory reset; UPS power supply (9) has no fault alarm; The electric turning gear is engaged.

3. A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor according to claim 2, characterized in that: In step 4, the startup process is specifically as follows: Q1, start the motor external water cooling system (20); Q2. Stop the lubricating oil pump; the lubricating oil pump includes a main oil pump (501) and a standby oil pump (502); Q3. Open the shutter of the lubricating oil station air cooler (11); Q4. Close the shutdown drain valve of the lubricating oil station air cooler (11); Q5. Test the main oil pump (501); Q6. Test the standby oil pump (502); Q7. Start the main oil pump (501); Q8, start the jacking oil pump (306) and the jacking oil pump (307); Q9, start the motor cooling fan (301) and the motor cooling fan (304); Q10. Open the dry gas seal inlet valve; Q11, opening the inlet valve; the inlet valve comprises an inlet cut-off valve (13) and a loading valve (14); Q12. Open the anti-surge valve (15) and keep it fully open; Q13. Open the emergency drain valve (16); Q14. Close the emergency drain valve (16); Q15, the centrifugal compressor (1) is charged to the designed low pressure value; Q16, close the inlet shut-off valve (13) and the loading valve (14); Q17, keep the inlet shut-off valve (13) and the loading valve (14) closed, the outlet shut-off valve (17) closed, and the anti-surge valve (15) fully open; Q18, inverter (4) closes; Q19, inverter (4) starts; Q20, the frequency converter (4) controls the motor (3) to start working; The minimum operating speed is 1000rpm-1100rpm.

4. A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor according to claim 3, characterized in that: In step 4, the minimum operating speed is 1044 rpm.

5. The method for controlling the low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor according to claim 1, characterized in that: In step 5, the preset warm-up time is 10 minutes to 20 minutes.

6. A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor according to claim 5, characterized in that: The preset warm-up time is 15 minutes.

7. A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor according to claim 3, characterized in that: In step 6, the shutdown process is specifically as follows: T1, the control system controls the motor (3) to reduce its speed through the frequency converter (4), and when the speed of the motor (3) drops to a preset speed, the frequency converter (4) is opened; T2, the control system controls the motor external water cooling system (20) to stop working; T3. The control system controls the motor (3) to stop working through the frequency converter (4), thus completing the shutdown of the unit.

8. A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor according to claim 7, characterized in that: In step T1, the preset rotation speed is 448 rpm.

9. A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor according to claim 8, characterized in that: In step 7, the venting process is specifically as follows: F1, the control system detects the fully closed state of the inlet valve, the fully closed state of the outlet cut-off valve (17), and the fully open state of the anti-surge valve (15); F2, the control system opens the emergency drain valve (16); F3. After the control system detects that the inlet pressure and outlet pressure have reached the design pressure, the venting process is completed.

10. A method for controlling a low-pressure and low-speed operation mode of an electric-driven pipeline centrifugal compressor according to claim 9, characterized in that: In step F3, the design pressure is 2.0 MPa.

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