Compressor unit turning control method and compressor unit

Abstract

The invention discloses a compressor unit turning control method and a compressor unit. The compressor unit turning method comprises the steps that the isolation gas system, the dry gas sealing system and the lubricating system are sequentially opened; when the pressure of the isolation gas system is kept at the first preset pressure and the dry gas sealing system and the lubricating system are both opened, the compressor is started, and an inlet and outlet valve and a pressurizing loading valve of the compressor are kept closed; the compressor is controlled to run at the preset rotating speed for preset turning time; and after the compressor stops rotating, the lubricating system is closed, and the dry gas sealing system and the isolation gas system are closed. According to the invention, shaft bending caused by long-time standby of the compressor and the main motor rotor of the compressor can be eliminated, the completeness of a compressor unit system is effectively detected, natural gas pressurization is avoided in the barring process, waste of pressurized natural gas is prevented, and the safety of the barring process is improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of natural gas transportation, and in particular to a compressor unit cranking control method and a compressor unit. Background Art

[0002] The oil and gas pipeline centrifugal compressor unit is an important equipment for long-distance transportation of natural gas. The oil and gas pipeline centrifugal compressor unit can increase the pressure of natural gas and improve the transportation flow.

[0003] To eliminate the effects of shaft bending caused by long periods of static operation, centrifugal compressor units need to be cranked at regular intervals. The traditional cranking process involves starting the compressor unit's auxiliary systems, pre-lubricating the bearings, opening the compressor charging valve, purging the compressor process pipeline, and pressurizing it to the inlet manifold pressure (4-7 MPa). The compressor's inlet and outlet valves are then fully opened, the driver is started, and the compressor is driven by the motor to the cranking speed. After cranking is completed (usually 30 minutes), the compressor unit is depressurized and shut down, resulting in a significant waste of natural gas (approximately 8,000 cubic meters per time) in the compressor process pipeline.

[0004] In addition, publication number "CN118188560A," titled "An Automatic Cranking Device and Method for a Natural Gas Transmission Centrifugal Compressor Unit," discloses a method for cranking the compressor unit using a cranking device. By modifying the compressor unit coupling structure and adding a cranking motor and other cranking devices, the coupling is driven by motor gear engagement, achieving non-pressurized cranking of the compressor unit. The cranking device with the aforementioned structure has the following problems: 1. It requires modifying the original compressor coupling component structure and adding a cranking motor and other devices, resulting in high modification costs; 2. The design parameters of the cranking device vary from unit to unit, making it difficult to generalize; 3. The addition of a cranking device to the station increases the operation and maintenance workload; 4. The safety and reliability of the device affects the overall stability of the unit. Summary of the Invention

[0005] The present invention provides a compressor unit cranking control method and a compressor unit to solve the problems of high cost, large operation and maintenance workload, poor promotion and low reliability caused by adding a cranking device for cranking, and to reduce the waste of natural gas during the cranking process and improve the safety of the cranking process.

[0006] In a first aspect, an embodiment of the present invention provides a method for controlling a cranking gear of a compressor unit.

[0007] The compressor unit includes a compressor, a main motor, a frequency converter, an isolation gas system, a dry gas sealing system, and a lubrication system. The frequency converter is connected to the main motor, and the main motor, the isolation gas system, the dry gas sealing system, and the lubrication system are all connected to the compressor. The cranking method of the compressor unit includes:

[0008] Opening the isolation gas system, the dry gas sealing system and the lubrication system in sequence;

[0009] When the pressure of the isolation gas system is maintained at a first preset pressure and the dry gas sealing system and the lubrication system are both opened, starting the compressor and keeping the inlet and outlet valves and the pressure loading valve of the compressor closed;

[0010] Controlling the compressor to operate at a preset speed for a preset cranking time;

[0011] After the compressor stops rotating, the lubrication system is closed, and the dry gas sealing system and the isolation gas system are closed.

[0012] Optionally, the sequentially opening of the isolation gas system, the dry gas sealing system, and the lubrication system includes:

[0013] Opening the isolation gas system and adjusting the pressure of the isolation gas system to maintain the first preset pressure, so that the isolation gas system delivers isolation gas to the compressor;

[0014] opening the dry gas sealing system and adjusting the pressure of the dry gas sealing system to maintain within a first preset pressure range, so that the dry gas sealing system delivers sealing gas to the compressor;

[0015] Start the lubrication system and adjust the pressure of the lubrication system to maintain a second preset pressure, so that the lubrication system delivers lubricating oil to the compressor and the main motor; wherein, the first preset pressure range is (A, B), A and B are greater than 0, and B>A; the first preset pressure is greater than the second preset pressure, and the second preset pressure is greater than B.

[0016] Optionally, before starting the lubrication system, the method further includes:

[0017] Check whether the parameters of the lubrication system are consistent with the parameters of the lubrication system shown in the process and instrument flow chart of the compressor unit;

[0018] If so, when the pressure of the isolation gas system remains at the first preset pressure and the pressure of the dry gas sealing system remains at the first preset pressure range, starting the lubrication system;

[0019] Before opening the dry gas sealing system, the method further comprises:

[0020] Determining whether the pressure of the isolation gas system maintains the first preset pressure;

[0021] If so, the dry gas sealing system is opened.

[0022] Optionally, when the pressure of the isolation gas system is maintained at a first preset pressure and the dry gas sealing system and the lubrication system are both opened, starting the compressor includes:

[0023] When the pressure of the isolation gas system is maintained at the first preset pressure, the dry gas sealing system is opened, and the pressure of the lubrication system is maintained at the second preset pressure, the compressor is started.

[0024] Optionally, a plurality of valves are provided between the isolation gas system, the dry gas sealing system, the lubrication system, and the compressor, and the valves include the inlet and outlet valves, the pressure loading valve, the automatic vent valve, and the anti-surge valve. Before sequentially opening the isolation gas system, the dry gas sealing system, and the lubrication system, the following steps may also be included:

[0025] After receiving the cranking command, check whether the isolation gas system, the dry gas sealing system, the lubrication system, the compressor, the main motor, and the inverter are in normal condition;

[0026] When it is determined that the isolation gas system, the dry gas sealing system, the lubrication system, and the compressor are in normal condition, the inlet and outlet valves, the pressure loading valve, and the automatic vent valve are checked to see if they are closed, and the anti-surge valve is checked to see if it is open.

[0027] If so, the steps of sequentially opening the isolation gas system, the dry gas sealing system, and the lubrication system are executed; if not, the steps of sequentially opening the isolation gas system, the dry gas sealing system, and the lubrication system are stopped.

[0028] Optionally, controlling the compressor to operate at a preset speed for a preset cranking time includes:

[0029] Controlling the main motor by the frequency converter so that the compressor maintains the preset speed;

[0030] After the compressor maintains the preset speed and runs for the preset cranking time, the compressor is turned off.

[0031] Optionally, after closing the dry gas sealing system and the isolation gas system, the method further includes:

[0032] Obtaining the cavity pressure of the compressor;

[0033] The compressor is depressurized according to the cavity pressure of the compressor.

[0034] Optionally, relieving the compressor according to the cavity pressure of the compressor includes:

[0035] When the cavity pressure of the compressor is greater than a first preset cavity pressure, opening the automatic vent valve on the compressor to relieve the pressure of the compressor;

[0036] During the process of depressurizing the compressor, when the cavity pressure of the compressor reaches a second preset cavity pressure, the automatic vent valve on the compressor is closed to stop depressurizing the compressor.

[0037] Optionally, the compressor unit cranking method further includes:

[0038] During the cranking process, the compressor's charging and loading valve switch instructions, inlet and outlet valve switch instructions, automatic vent valve switch instructions, and anti-surge valve switch instructions are not triggered.

[0039] In the second aspect, an embodiment of the present invention also provides a compressor unit, which includes a control module, a main motor, a frequency converter, a compressor, an isolation gas system, a dry gas sealing system and a lubrication system. The frequency converter is connected to the main motor, and the main motor, the isolation gas system, the dry gas sealing system and the lubrication system are all connected to the compressor. The control module is used to execute the compressor unit cranking control method described in any embodiment of the present invention.

[0040] The present invention provides a cranking control method for a compressor unit and a compressor unit. The cranking control method for the compressor unit opens the isolation gas system, the dry gas sealing system and the lubrication system in sequence, and first seals the pipeline labyrinth around the compressor and provides isolation gas before the compressor is cranked and started, and then provides main sealing gas, and then the lubrication system and the compressor can be started. When the pressure of the isolation gas system maintains a first preset pressure and the dry gas sealing system and the lubrication system are both opened, the compressor is started, and the inlet and outlet valves and the pressure loading valve of the compressor are kept closed to provide a suitable cranking environment for the compressor. After starting the compressor, by controlling the compressor to run at a preset speed for a preset cranking time, the shaft bending caused by the long-term standby of the compressor and its main motor rotor can be eliminated, and the integrity of the compressor unit system can be effectively tested. In the process of cranking the compressor, there is no need to use natural gas to crank the compressor, so that the natural gas in the pipeline where the compressor is located will not be wasted, and the cranking cost is reduced. After the compressor stops rotating, the lubrication system is closed, and the dry gas sealing system and the isolation gas system are closed. The present invention can solve the problems of high cost, heavy operation and maintenance workload, poor promotion and low reliability caused by adding a cranking device for cranking, and can avoid the pressurization of natural gas during the cranking process, prevent the waste of pressurized natural gas, and improve the safety of the cranking process. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A flowchart of a compressor unit cranking control method provided by an embodiment of the present invention;

[0042] Figure 2 A flowchart of another compressor unit cranking control method provided by an embodiment of the present invention;

[0043] Figure 3 A flowchart of a self-test method for a compressor unit provided by an embodiment of the present invention;

[0044] Figure 4 A flowchart of another compressor unit cranking control method provided by an embodiment of the present invention;

[0045] Figure 5 Schematic diagram of the structure of a compressor unit in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0047] An embodiment of the present invention provides a method for controlling the cranking of a compressor unit. This embodiment is suitable for application scenarios in which the compressor unit is cranked. The embodiment of the present invention adopts a non-pressurized cranking process and does not use natural gas to purge or pressurize the compressor process pipeline. This will not waste the natural gas in the compressor process pipeline, thereby directly saving costs. Figure 1 A flowchart of a method for controlling a cranking gear of a compressor unit provided in an embodiment of the present invention. The compressor unit in the embodiment of the present invention includes a compressor, a main motor, a frequency converter, an isolation gas system, a dry gas sealing system, and a lubrication system. The frequency converter is connected to the main motor, and the main motor, the isolation gas system, the dry gas sealing system, and the lubrication system are all connected to the compressor. Figure 1 As shown, the compressor unit cranking control method includes:

[0048] S110. Open the isolation gas system, dry gas sealing system and lubrication system in sequence.

[0049] The compressor unit may be a centrifugal compressor unit for oil and gas pipelines, specifically an electrically driven centrifugal compressor unit, which includes a compressor and auxiliary equipment, including an isolation gas system, a dry gas sealing system, and a lubrication system. The isolation gas system may be connected to the compressor via a pipeline, and the isolation gas system may provide isolation gas to the compressor and the surrounding pipelines, thereby sealing the compressor and the surrounding pipelines. The dry gas sealing system may be connected to the compressor via a pipeline to provide sealing gas to the compressor. The lubrication system may be connected to the compressor to provide lubricating oil to the compressor.

[0050] Specifically, before cranking the compressor, the isolation gas system, dry gas sealing system, and lubrication system must be started in sequence, allowing the compressor to be in a depressurized state. The isolation gas system first seals the pipe maze surrounding the compressor and provides isolation gas. The dry gas sealing system then provides sealing gas to the compressor, and finally, the lubrication system provides lubricating oil to the compressor. This ensures that the compressor can be cranked in a depressurized state, eliminating the need to purge or pressurize the compressor pipeline with natural gas, and thus preventing waste of natural gas in the compressor's process pipeline.

[0051] S120. When the pressure of the isolation gas system is maintained at a first preset pressure and the dry gas sealing system and the lubrication system are both opened, start the compressor and keep the inlet and outlet valves and the pressure loading valve of the compressor closed.

[0052] Specifically, by adjusting the pressure of the isolation gas provided by the isolation gas system to maintain a first preset pressure, and providing sealing gas to the compressor through the dry gas sealing system, the shaft end of the compressor can be sealed at two levels to prevent gas leakage in the compressor. The lubrication system provides lubricating oil to the compressor, thereby providing lubrication for the compressor. When the pressure of the isolation gas system is maintained at the first preset pressure, illustratively, the first preset pressure is 0.3MPa, and the dry gas sealing system and the lubrication system are both opened, the compressor can be started to ensure that the compressor is in a suitable cranking environment, and the inlet and outlet valves and the pressure loading valve of the compressor are kept closed, thereby avoiding the pressurization of natural gas during the cranking process and preventing the waste of pressurized natural gas.

[0053] S130: Control the compressor to run at a preset speed for a preset cranking time.

[0054] Specifically, to ensure the cranking effect of the compressor, the compressor needs to be controlled to run at a preset speed for a preset cranking time. During the cranking process of the compressor, there is no need to use natural gas to crank the compressor, thereby avoiding waste of natural gas in the pipeline where the compressor is located and reducing the cranking cost.

[0055] S140. After the compressor stops rotating, shut down the lubrication system, the dry gas sealing system and the isolation gas system.

[0056] Specifically, after the compressor stops rotating, the lubrication system, the dry gas sealing system and the isolation gas system can be closed in sequence in the reverse order of opening the isolation gas system, the dry gas sealing system and the lubrication system, so as to prevent the waste of lubricating oil, sealing gas and isolation gas. In addition, since there is no need to add a cranking device to crank the compressor unit, the cranking cost and operation and maintenance workload of the compressor can be reduced, and the problem of natural gas being wasted in the compressor process pipeline when the compressor is shut down for pressure relief after cranking is avoided. It also avoids safety issues caused by the discharge of natural gas, and improves the safety of the cranking process. In addition, the embodiment of the present invention only optimizes the method logic without changing the structure and protection measures of the compressor unit, thereby reducing the waste of natural gas and achieving emission reduction benefits.

[0057] An embodiment of the present invention provides a method for controlling the cranking of a compressor unit. The method for controlling the cranking of a compressor unit opens the isolation gas system, the dry gas sealing system and the lubrication system in sequence, and first seals the pipe labyrinth around the compressor and provides isolation gas before the compressor is cranked and started, and then provides main sealing gas. Only then can the lubrication system and the compressor be started. When the pressure of the isolation gas system maintains a first preset pressure and the dry gas sealing system and the lubrication system are both opened, the compressor is started, and the inlet and outlet valves and the pressure loading valve of the compressor are kept closed to provide a suitable cranking environment for the compressor. After starting the compressor, by controlling the compressor to run at a preset speed for a preset cranking time, the shaft bending caused by the long-term standby of the compressor and its main motor rotor can be eliminated, and the integrity of the compressor unit system can be effectively tested. In the process of cranking the compressor, there is no need to use natural gas to crank the compressor, so that the natural gas in the pipeline where the compressor is located will not be wasted, and the cranking cost is reduced. After the compressor stops rotating, the lubrication system is closed, and the dry gas sealing system and the isolation gas system are closed. The present invention can solve the problems of high cost, heavy operation and maintenance workload, poor promotion and low reliability caused by adding a cranking device for cranking, and can avoid the pressurization of natural gas during the cranking process, prevent the waste of pressurized natural gas, and improve the safety of the cranking process.

[0058] In order to further improve the control of the cranking process of the compressor unit, the embodiment of the present invention also provides another compressor unit cranking control method. Figure 2 A flowchart of another compressor unit cranking control method provided by an embodiment of the present invention is shown in FIG. Figure 2 As shown, the compressor unit cranking control method includes:

[0059] S210. Open the isolation gas system and adjust the pressure of the isolation gas system to maintain a first preset pressure, so that the isolation gas system delivers isolation gas to the compressor.

[0060] Specifically, before starting the compressor, the isolation gas system must be started first. The isolation gas system is used to seal the pipe maze around the compressor and provide isolation gas, and the pressure of the isolation gas system is adjusted to maintain a first preset pressure. The pressure of the isolation gas in the isolation gas system can be checked through a differential pressure transmitter, and the difference between the actual pressure of the isolation gas system and the first preset pressure is controlled to be less than or equal to the preset difference, thereby ensuring that the pressure of the isolation gas system maintains the first preset pressure. For example, the first preset pressure is 0.3Mpa, and the preset difference is 0.05MPa. By adjusting the pressure of the isolation gas system to maintain the first preset pressure, the shaft end of the compressor is sealed to prevent lubricating oil from leaking into the compressor cavity.

[0061] Optionally, the isolation gas is instrument air.

[0062] S220 , opening the dry gas sealing system and adjusting the pressure of the dry gas sealing system to maintain within a first preset pressure range, so that the dry gas sealing system delivers sealing gas to the compressor.

[0063] Specifically, after the isolation gas system is opened and its pressure is adjusted to maintain a first preset pressure, the dry gas sealing system is opened. After the dry gas sealing system is opened, since the cavity of the dry gas sealing system is at atmospheric pressure, the pressure of the dry gas sealing system is maintained within the first preset pressure range, allowing the dry gas sealing system to deliver sealing gas to the compressor, thereby providing a two-stage seal for the compressor shaft end using the isolation gas and sealing gas.

[0064] Optionally, before opening the dry gas sealing system, the method further includes: determining whether the pressure of the isolation gas system maintains a first preset pressure; if so, opening the dry gas sealing system.

[0065] Specifically, before opening the dry gas sealing system, it is necessary to ensure that the pressure of the isolation gas system maintains a first preset pressure, otherwise the dry gas sealing system will not be opened.

[0066] S230. Start the lubrication system and adjust the pressure of the lubrication system to maintain a second preset pressure, so that the lubrication system delivers lubricating oil to the compressor and the main motor; wherein, the first preset pressure range is (A, B), A and B are greater than 0, and B>A; the first preset pressure is greater than the second preset pressure, and the second preset pressure is greater than B.

[0067] Specifically, after opening the isolation gas system and the dry gas sealing system, the lubricating oil pump in the lubrication system is turned on to deliver lubricating oil to the compressor. The lubrication system pressure is adjusted to maintain a second preset pressure, thereby providing lubrication for the compressor and ensuring lubrication during the compressor cranking process. Optionally, the first preset pressure range is (0.04, 0.2) MPa, and the second preset pressure is 0.26 MPa.

[0068] Optionally, before starting the lubrication system, the following steps may also be performed:

[0069] Check whether the parameters of the lubrication system are consistent with the parameters of the lubrication system shown in the process and instrument flow chart of the compressor unit; if so, start the lubrication system when the pressure of the isolation gas system remains at the first preset pressure and the pressure of the dry gas sealing system remains within the first preset pressure range.

[0070] Specifically, to avoid incorrect startup sequences, the signal of the isolation gas differential pressure transmitter can be interlocked with the startup signal of the lubrication system. The lubrication system is not allowed to start when the isolation gas pressure is insufficient. Before starting the lubrication system, it is necessary to check whether the parameters of the lubrication system are consistent with the parameters of the lubrication system shown in the process and instrument flow chart of the compressor unit. When there is no alarm signal for the lubrication system, the pressure of the isolation gas system remains within the first preset pressure, and the pressure of the dry gas sealing system remains within the first preset pressure range, the lubrication system can be started to prevent the dry gas sealing system from failing due to premature opening of the lubrication system.

[0071] S240. When the pressure of the isolation gas system is maintained at a first preset pressure and the dry gas sealing system and the lubrication system are both opened, start the compressor and keep the inlet and outlet valves and the pressure loading valve of the compressor closed.

[0072] Optionally, when the pressure of the isolation gas system is maintained at a first preset pressure, the dry gas sealing system is opened, and the pressure of the lubrication system is maintained at a second preset pressure, the compressor is started.

[0073] Specifically, before starting the compressor, it is necessary to ensure that the isolation gas system, dry gas sealing system and lubrication system are open so that the compressor is in a suitable cranking environment. The pressure of the isolation gas system needs to be maintained at a first preset pressure, and the pressure of the lubrication system needs to be maintained at a second preset pressure, thereby ensuring the cranking effect of the compressor.

[0074] S250, controlling the main motor through the frequency converter to keep the compressor at a preset speed; after the compressor runs at the preset speed for a preset cranking time, turning off the compressor.

[0075] Specifically, the compressor unit includes a frequency converter and a main motor. These two components control the compressor's cranking mode. By adjusting the frequency converter parameters to control the main motor's operation, the compressor maintains a preset speed. For example, by adjusting the frequency converter parameters to approximately 5%, the compressor output speed is approximately 250 rpm, meaning the preset speed can be 250 rpm and the preset cranking time can be 1 minute. After the compressor maintains the preset speed, a timer starts counting down the preset cranking time, and then the compressor shuts down. Using a frequency converter to control the compressor's cranking process can save cranking time, improve compressor cranking efficiency, and reduce operational difficulty during the cranking process.

[0076] S260. After the compressor stops rotating, turn off the lubrication system, dry gas sealing system and isolation gas system.

[0077] Optionally, multiple valves are installed between the isolation gas system, dry gas sealing system, lubrication system, and compressor. The valves include inlet and outlet valves, pressure loading valves, automatic vent valves, and anti-surge valves. Before opening the isolation gas system, dry gas sealing system, and lubrication system in sequence, the compressor needs to be self-checked. Figure 3 A flowchart of a self-test method for a compressor unit according to an embodiment of the present invention is shown in FIG. Figure 3 As shown, before opening the isolation gas system, dry gas sealing system and lubrication system in sequence, the following steps are also required:

[0078] S310. After receiving the cranking command, check whether the isolation gas system, dry gas sealing system, lubrication system, compressor, main motor, and inverter are in normal condition.

[0079] Specifically, after receiving the cranking command, it is necessary to check whether the status of all electrical equipment in the compressor unit is normal, including checking whether the status of the isolation gas system, dry gas sealing system, lubrication system, compressor, main motor, and inverter are normal.

[0080] S320. When it is determined that the isolation gas system, dry gas sealing system, lubrication system, compressor, main motor, and inverter are in normal condition, continue to check whether the inlet and outlet valves, pressure loading valve, and automatic vent valve are closed, and whether the anti-surge valve is open.

[0081] Specifically, when it is determined that the status of the isolation gas system, dry gas sealing system, lubrication system, compressor, main motor, and inverter are normal, it is necessary to continue to check whether the positions of multiple valves in the isolation gas system, dry gas sealing system, lubrication system, and compressor are consistent with the valve positions shown in the process and instrument flow chart of the compressor unit, that is, whether the inlet and outlet valves, charging loading valve, and automatic vent valve are closed, and whether the position of the anti-surge valve is open, to ensure that the switching status of each valve is in the preset state to prevent gas or lubricating oil leakage after opening the isolation gas system, dry gas sealing system, and lubrication system, which may cause the compressor to be unable to complete the cranking.

[0082] S330: If yes, then open the isolation gas system, dry gas sealing system and lubrication system in sequence; if no, then stop opening the isolation gas system, dry gas sealing system and lubrication system in sequence.

[0083] Specifically, only after ensuring that the isolation gas system, dry gas sealing system, lubrication system, and compressor are in normal condition, and the positions of multiple valves are consistent with the valve positions shown in the process and instrument flow chart of the compressor unit, can the isolation gas system, dry gas sealing system, and lubrication system be opened to ensure that the compressor can complete the cranking process.

[0084] In some embodiments of the present invention, during the cranking process, the compressor's charging and loading valve switch instructions, inlet and outlet valve switch instructions, automatic vent valve switch instructions, and anti-surge valve switch instructions are not triggered.

[0085] Specifically, during the cranking process of the compressor, the compressor's charging and loading valve switching instructions, inlet and outlet valve switching instructions, automatic vent valve switching instructions, and anti-surge valve switching instructions are not triggered. This prevents the compressor from performing operations such as charging and depressurizing during the cranking process, which could result in the compressor being unable to complete cranking. Exemplarily, the cranking process of the compressor may include shutting down the lubrication system, dry gas sealing system, and isolation gas system, as well as the previous steps. The compressor unit cranking control method according to an embodiment of the present invention reduces natural gas waste by cranking the compressor unit in a depressurized state.

[0086] In some embodiments of the present invention, after closing the dry gas sealing system and the isolation gas system, the method further includes: obtaining the cavity pressure of the compressor; and relieving the compressor according to the cavity pressure of the compressor.

[0087] Specifically, after the compressor cranking is completed, the cavity pressure of the compressor needs to be monitored, and the compressor needs to be vented and depressurized according to the cavity pressure of the compressor.

[0088] Optionally, the compressor is depressurized according to the cavity pressure of the compressor, including:

[0089] When the cavity pressure of the compressor is greater than the first preset cavity pressure, the automatic vent valve on the compressor is opened to relieve the pressure of the compressor; during the process of relieving the pressure of the compressor, when the cavity pressure of the compressor is the second preset cavity pressure, the automatic vent valve on the compressor is closed to stop relieving the pressure of the compressor.

[0090] Specifically, the first preset cavity pressure can be 0.1Mpa, and the second preset cavity pressure can be 0-0.05Mpa. When the cavity pressure of the compressor is greater than 0.1Mpa, the automatic vent valve on the compressor is opened to automatically relieve the pressure of the compressor; during the process of relieving the pressure of the compressor, when the cavity pressure of the compressor is less than or equal to 0.05Mpa, the automatic vent valve on the compressor is closed to stop relieving the pressure of the compressor.

[0091] Figure 4 A flowchart of another compressor unit cranking control method provided by an embodiment of the present invention is shown in FIG. Figure 4As shown, after the cranking logic of the compressor unit is started, the system self-check is first performed, and then the isolation gas system is opened to ensure that the isolation gas system pressure is normal. Then the dry gas sealing system is opened to ensure that the dry gas sealing system pressure is normal. Then the lubrication system is opened to ensure that the lubricating oil pressure is normal. Then the compressor is controlled to start and run at a preset speed. After the timer counts down the preset cranking time, the compressor is shut down. After detecting that the compressor speed is zero, the lubrication system, dry gas sealing system and isolation gas system are shut down. When the cranking shutdown is completed, the instrument air supply to the isolation gas system must be cut off after the oil pumps of the compressor and lubrication system are turned off. In addition, the instrument air shutdown can be delayed until 30 minutes after the lubricating oil pump of the lubrication system is turned off. The cranking process is completed. After the cranking is completed, the cavity pressure of the compressor needs to be monitored. If the pressure exceeds 0.1MPa, it is automatically discharged. The embodiment of the present invention adopts a non-pressurized cranking process. Natural gas is not used to purge or pressurize the compressor process pipeline. There is no waste of natural gas in the compressor process pipeline, which directly saves costs and ensures stable and reliable equipment operation.

[0092] The traditional cranking process involves starting the compressor unit's auxiliary systems, pre-lubricating bearings, opening the compressor charging valve, purging the compressor process pipeline, and pressurizing it to the inlet manifold pressure (4-7 MPa). The compressor's inlet and outlet valves are then fully opened, the driver is started, and the motor drives the compressor to the cranking speed. After cranking is complete (typically 30 minutes), the compressor unit is depressurized and shut down, resulting in significant waste of natural gas (approximately 8,000 cubic meters per cycle) in the compressor process pipeline. The embodiments of the present invention can reduce natural gas waste during the cranking process and improve the safety of the cranking process.

[0093] On the one hand, the compressor unit cranking control method in the embodiment of the present invention can avoid a large amount of natural gas waste during the cranking process, thereby saving costs. The annual natural gas saving per unit is: 8,000 cubic meters / time × 12 months = 96,000 cubic meters / year. For example, about 410 sets of centrifugal compressor units are put into use (50% of which are standby units on average throughout the year), and the annual natural gas saving is: 410 × 50% × 96,000 cubic meters = 19.68 million cubic meters / year, and the cost saving (at 4 yuan / cubic meter) is: 19.68 million cubic meters × 4 yuan = 78.72 million yuan / year; on the other hand, from the perspective of clean energy substitution and the environmental protection effect generated by gas, 24.6 million cubic meters of natural gas per year is equivalent to replacing 26,200 tons of standard coal, reducing 28,700 tons of carbon dioxide, 941 tons of sulfur dioxide, 14,300 tons of dust and 235 tons of nitrogen oxides emissions. Its environmental protection benefit is equivalent to planting 89,300 hectares of broad-leaved forest, making an outstanding contribution to improving environmental quality. Therefore, the compressor unit cranking control method in the embodiment of the present invention can avoid a large amount of natural gas waste during the cranking process, save costs, and reduce carbon emissions. It has a high return on investment, simple logical transformation, and no new fixed investment.

[0094] An embodiment of the present invention provides a method for controlling the cranking of a compressor unit. The method opens an isolation gas system, a dry gas sealing system, and a lubrication system in sequence. When the pressure of the isolation gas system is maintained at a first preset pressure and the dry gas sealing system and the lubrication system are both opened, the compressor is started and the compressor is controlled to run at a preset speed for a preset cranking time. Therefore, during the cranking process of the compressor, there is no need to use natural gas to crank the compressor, thereby avoiding waste of natural gas in the pipeline where the compressor is located, reducing the cranking cost, and eliminating the need to add a cranking device to crank the compressor unit. This reduces the cost and operation and maintenance workload, and can avoid pressurizing natural gas during the cranking process, thereby preventing waste of pressurized natural gas and improving the safety of the cranking process.

[0095] The embodiment of the present invention further provides a compressor unit, Figure 5 FIG. 1 is a structural diagram of a compressor unit according to an embodiment of the present invention. Figure 5 As shown, the compressor unit includes a control module 110, a compressor 120, an isolation gas system 130, a dry gas sealing system 140, a lubrication system 150, a frequency converter 160 and a main motor 170. The frequency converter 160 is connected to the main motor 170. The main motor 170, the isolation gas system 130, the dry gas sealing system 140 and the lubrication system 150 are all connected to the compressor 120, and the main motor 170 and the compressor 120 are connected through a coupling. The control module 110 is respectively connected to the frequency converter 160, the compressor 120, the isolation gas system 130, the dry gas sealing system 140 and the lubrication system 150. 110 is also connected to multiple valves of the compressor 120, which include inlet and outlet valves, pressure loading valves, automatic vent valves and anti-surge valves. The control module 110 can control the opening and closing of the multiple valves. The control module 110 can be implemented in the form of hardware and / or software. The control module 110 is used to execute the compressor unit cranking control method in any embodiment of the present invention, and control the inverter 160, the compressor 120, the isolation gas system 130, the dry gas sealing system 140 and the lubrication system 150 to achieve the function and technical effect of the compressor unit cranking control method in any embodiment of the present invention.

[0096] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments, and substitutions are possible for those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for controlling a cranking gear of a compressor unit, characterized in that: The compressor unit includes a compressor, a main motor, a frequency converter, an isolation gas system, a dry gas sealing system, and a lubrication system. The frequency converter is connected to the main motor, and the main motor, the isolation gas system, the dry gas sealing system, and the lubrication system are all connected to the compressor. The cranking method of the compressor unit includes: Opening the isolation gas system, the dry gas sealing system and the lubrication system in sequence; When the pressure of the isolation gas system is maintained at a first preset pressure and the dry gas sealing system and the lubrication system are both opened, starting the compressor and keeping the inlet and outlet valves and the pressure loading valve of the compressor closed; Controlling the compressor to operate at a preset speed for a preset cranking time; After the compressor stops rotating, the lubrication system is closed, and the dry gas sealing system and the isolation gas system are closed.

2. The method for controlling the cranking of a compressor unit according to claim 1, characterized in that: The sequentially opening of the isolation gas system, the dry gas sealing system, and the lubrication system includes: Opening the isolation gas system and adjusting the pressure of the isolation gas system to maintain the first preset pressure, so that the isolation gas system delivers isolation gas to the compressor; opening the dry gas sealing system and adjusting the pressure of the dry gas sealing system to maintain within a first preset pressure range, so that the dry gas sealing system delivers sealing gas to the compressor; Start the lubrication system and adjust the pressure of the lubrication system to maintain a second preset pressure, so that the lubrication system delivers lubricating oil to the compressor and the main motor; wherein, the first preset pressure range is (A, B), A and B are greater than 0, and B>A; the first preset pressure is greater than the second preset pressure, and the second preset pressure is greater than B.

3. The method for controlling the cranking of a compressor unit according to claim 2, characterized in that: Before starting the lubrication system, the method further comprises: Check whether the parameters of the lubrication system are consistent with the parameters of the lubrication system shown in the process and instrument flow chart of the compressor unit; If so, when the pressure of the isolation gas system remains at the first preset pressure and the pressure of the dry gas sealing system remains at the first preset pressure range, starting the lubrication system; Before opening the dry gas sealing system, the method further comprises: Determining whether the pressure of the isolation gas system maintains the first preset pressure; If so, the dry gas sealing system is opened.

4. The method for controlling the cranking of a compressor unit according to claim 2, characterized in that: When the pressure of the isolation gas system is maintained at a first preset pressure and the dry gas sealing system and the lubrication system are both opened, starting the compressor comprises: When the pressure of the isolation gas system is maintained at the first preset pressure, the dry gas sealing system is opened, and the pressure of the lubrication system is maintained at the second preset pressure, the compressor is started.

5. The method for controlling the cranking of a compressor unit according to claim 1, characterized in that: A plurality of valves are provided between the isolation gas system, the dry gas sealing system, the lubrication system, and the compressor. The valves include the inlet and outlet valves, the pressure loading valve, the automatic vent valve, and the anti-surge valve. Before sequentially opening the isolation gas system, the dry gas sealing system, and the lubrication system, the following steps are further included: After receiving the cranking command, check whether the isolation gas system, the dry gas sealing system, the lubrication system, the compressor, the main motor, and the inverter are in normal condition; When it is determined that the isolation gas system, the dry gas sealing system, the lubrication system, the compressor, the main motor, and the frequency converter are in normal condition, the inlet and outlet valves, the pressure loading valve, and the automatic vent valve are checked to see if they are closed, and the anti-surge valve is checked to see if it is open. If so, the steps of sequentially opening the isolation gas system, the dry gas sealing system, and the lubrication system are executed; if not, the steps of sequentially opening the isolation gas system, the dry gas sealing system, and the lubrication system are stopped.

6. The method for controlling the cranking gear of a compressor unit according to claim 1, characterized in that: The step of controlling the compressor to operate at a preset speed for a preset cranking time includes: Controlling the main motor by the frequency converter so that the compressor maintains the preset speed; After the compressor maintains the preset speed and runs for the preset cranking time, the compressor is turned off.

7. The method for controlling the cranking of a compressor unit according to claim 1, characterized in that: After closing the dry gas sealing system and the isolation gas system, the method further comprises: Obtaining the cavity pressure of the compressor; The compressor is depressurized according to the cavity pressure of the compressor.

8. The method for controlling the cranking gear of a compressor unit according to claim 7, characterized in that: Relieving pressure from the compressor according to the cavity pressure of the compressor, comprising: When the cavity pressure of the compressor is greater than a first preset cavity pressure, opening the automatic vent valve on the compressor to relieve the pressure of the compressor; During the process of depressurizing the compressor, when the cavity pressure of the compressor reaches a second preset cavity pressure, the automatic vent valve on the compressor is closed to stop depressurizing the compressor.

9. The method for controlling the cranking gear of a compressor unit according to any one of claims 1 to 8, characterized in that: The compressor unit cranking method further includes: During the cranking process, the compressor's charging and loading valve switch instructions, inlet and outlet valve switch instructions, automatic vent valve switch instructions, and anti-surge valve switch instructions are not triggered.

10. A compressor unit, characterized in that: The compressor unit includes a control module, a main motor, a frequency converter, a compressor, an isolation gas system, a dry gas sealing system and a lubrication system. The frequency converter is connected to the main motor, and the main motor, the isolation gas system, the dry gas sealing system and the lubrication system are all connected to the compressor. The control module is used to execute the compressor unit cranking control method described in any one of claims 1-9.

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