Automatic control system of vacuum pump unit

Abstract

The invention belongs to the technical field of liquid variable-volume machinery, and particularly relates to an automatic control system of a vacuum pump unit, which comprises a liquid ring vacuum pump, the liquid ring vacuum pump is respectively connected with an atmospheric jet pump and a gas-liquid separation tank, and the gas-liquid separation tank, a cooler and the liquid ring vacuum pump are sequentially connected. An atmosphere jet pump automatic switching control unit is arranged on a pipeline between the liquid ring vacuum pump and the outside, and a pneumatic backflow adjusting valve PID voltage stabilization control unit is arranged on a gas loop between the gas-liquid separation tank and the liquid ring vacuum pump. A vacuum pump working fluid alarm and shutdown interlocking control unit is arranged on a pipeline between the cooler and the liquid ring vacuum pump, a fluid supplementing and discharging pipeline is arranged on the gas-liquid separation tank, and a gas-liquid separation tank automatic fluid supplementing and discharging control unit is arranged on the fluid supplementing and discharging pipeline. Various operation parameters of the vacuum pump unit can be rapidly adjusted under different working conditions, and stable operation of the vacuum pump unit is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid variable capacity machinery, and in particular relates to an automatic control system for a vacuum pump unit. Background Art

[0002] Vacuum obtaining equipment is a device used to create and maintain a vacuum environment in a specific space, and it plays an important role in industrial production. The application scope of vacuum obtaining equipment is very wide, covering many important fields such as semiconductor manufacturing, food packaging, and chemical analysis. Among them, the market demand for non-standard customized and intelligent skid-mounted integrated vacuum pump units according to different needs is showing an increasing trend, and it has become a new development direction for vacuum obtaining equipment.

[0003] For skid-mounted integrated vacuum pump units, their automated operation and precise adjustment are mainly achieved through the automatic control logic system. The automatic control logic system is a highly integrated automated control system that integrates key components such as sensors, actuators, and controllers. However, in actual operation, the automatic control logic system often encounters various operating fluctuations, such as changes in the load on the vacuum pump unit, unstable power supply, and interference from the external environment. When these situations occur, a series of adverse effects will occur, resulting in unstable vacuum, which in turn affects product quality and production efficiency.

[0004] Chinese patent CN105484969A discloses a vacuum pump system having a main vacuum pump for evacuating a chamber. An auxiliary pump is connected to the outlet of the main vacuum pump. In addition, a control device is provided for enabling the auxiliary pump within a limited range of pressure present at the outlet. The control device only includes mechanical components. The patent realizes automatic switching of the auxiliary pump through a mechanical structure, effectively reducing energy consumption in standby mode, but the control parameters of the patent are single, and the control logic only relies on the pressure at the outlet of the main vacuum pump, which is difficult to cope with complex control requirements under multiple operating conditions. When the vacuum pump unit faces load changes, abnormal working fluid level, etc., simple mechanical pressure control cannot achieve the adjustment of operating parameters such as liquid level, flow, and multi-pump collaborative work, resulting in unstable vacuum or equipment operation risks. Summary of the invention

[0005] The object of the present invention is to provide an automatic control system for a vacuum pump unit, which can monitor and adjust the operating status of the vacuum pump unit in real time when the load borne by the vacuum pump unit changes. At the same time, it can quickly adjust the various operating parameters of the vacuum pump unit under different working conditions to avoid the vacuum pump unit being in a bad operating state due to fluctuations in working conditions, thereby ensuring the stability of the vacuum degree.

[0006] To achieve the above object, the technical solution of the present invention is: The automatic control system of the vacuum pump unit described in the present invention comprises a liquid ring vacuum pump, which is respectively connected to an atmospheric jet pump and a gas-liquid separation tank, and the gas-liquid separation tank and a cooler are connected to the liquid ring vacuum pump in sequence. The liquid ring vacuum pump and the atmospheric jet pump extract process gas from the outside through a pipeline, and the process gas is mixed with the working fluid in the liquid ring vacuum pump and enters the gas-liquid separation tank for gas-liquid separation. The separated process gas returns to the liquid ring vacuum pump, and the separated working fluid is cooled by the cooler and returns to the liquid ring vacuum pump. An automatic switching control unit for the atmospheric jet pump is arranged on the pipeline between the liquid ring vacuum pump and the outside, and the automatic switching control unit for the atmospheric jet pump adjusts the suction degree of the atmospheric jet pump and the liquid ring vacuum pump according to the pressure of the external process gas. The gas-liquid separation tank and A pneumatic reflux regulating valve PID voltage stabilization control unit is provided on the gas circuit between the liquid ring vacuum pumps, and the pneumatic reflux regulating valve PID voltage stabilization control unit adjusts the flow rate of the reflux gas according to the pressure of the gas entering the liquid ring vacuum pump; a vacuum pump working fluid alarm and shutdown interlock control unit is provided on the pipeline between the cooler and the liquid ring vacuum pump, and the vacuum pump working fluid alarm and shutdown interlock control unit monitors the flow rate of the working fluid in the pipeline, and triggers an alarm and / or shuts down the liquid ring vacuum pump when the flow rate is insufficient; a liquid replenishment and drainage pipeline is provided on the gas-liquid separation tank, and a gas-liquid separation tank automatic liquid replenishment and drainage control unit is provided on the liquid replenishment and drainage pipeline, and the gas-liquid separation tank automatic liquid replenishment and drainage control unit performs liquid replenishment or drainage operations on the gas-liquid separation tank according to the liquid level of the working fluid in the gas-liquid separation tank.

[0007] Furthermore, the automatic liquid replenishment and drainage control unit of the gas-liquid separation tank includes a liquid level transmitter, a liquid replenishment valve, a liquid drain valve and a liquid level indication control alarm. The liquid level transmitter is cooperatively arranged on the gas-liquid separation tank. An air outlet pipe and a liquid replenishment pipe are arranged on the top of the gas-liquid separation tank. An automatic liquid outlet pipe and a liquid inlet pipe are arranged on the bottom of the gas-liquid separation tank. The liquid replenishment valve is cooperatively arranged on the liquid replenishment pipe, and the liquid drain valve is cooperatively arranged on the automatic liquid outlet pipe. The liquid level transmitter, the liquid replenishment valve and the liquid drain valve are all electrically connected to the liquid level indication control alarm.

[0008] Furthermore, the liquid level transmitter transmits the liquid level signal of the working liquid in the gas-liquid separation tank to the liquid level indication control alarm. When the liquid level value of the working liquid in the gas-liquid separation tank is ≤175mm, the liquid level indication control alarm sends an opening command to the liquid replenishing valve. After a delay of 3 seconds, the liquid replenishing valve opens and starts to replenish the working liquid. When the liquid level value of the working liquid in the gas-liquid separation tank is ≥250mm, the liquid level indication control alarm sends a closing command to the liquid replenishing valve, the liquid replenishing valve closes, and the replenishing of the working liquid stops. When the liquid level value of the working liquid in the gas-liquid separation tank is ≥325mm, the liquid The level indication control alarm sends an open command to the drain valve. After a delay of 3 seconds, the drain valve opens and the working fluid in the gas-liquid separation tank begins to be discharged. When the liquid level value of the working fluid in the gas-liquid separation tank is ≤250mm, the level indication control alarm sends a closing command to the drain valve, the drain valve closes, and the discharge of the working fluid stops. When the liquid level value of the working fluid in the gas-liquid separation tank is ≤100mm, the level indication control alarm triggers a low level alarm. When the liquid level value of the working fluid in the gas-liquid separation tank is ≥400mm, the level indication control alarm triggers a high level alarm.

[0009] Furthermore, the atmospheric jet pump automatic switching control unit includes a pressure transmitter, a bypass pneumatic ball valve, a main pneumatic ball valve, a loop pneumatic ball valve and a pressure transmitter controller. The pressure transmitter is arranged on the pipeline between the liquid ring vacuum pump and the outside world. The pipeline between the liquid ring vacuum pump and the outside world includes an intake pipe, a mixed intake pipe and an intake main pipe. The liquid ring vacuum pump, the intake pipe, the mixed intake pipe and the intake main pipe are connected in sequence. The atmospheric jet pump is respectively connected with a bypass pipe, a return air branch pipe and a connecting pipe. One end of the air jet pump is connected to the intake pipe through a bypass pipe, and the other end of the atmospheric jet pump is connected to the intake pipe through a connecting pipe. A pressure transmitter is arranged on the intake main pipe, a bypass pneumatic ball valve is arranged on the bypass pipe, a main pneumatic ball valve is arranged on the intake pipe and the main pneumatic ball valve is located between the bypass pipe and the connecting pipe, and a loop pneumatic ball valve is arranged on the return air branch pipe. The pressure transmitter, the bypass pneumatic ball valve, the main pneumatic ball valve and the loop pneumatic ball valve are all electrically connected to a pressure transmitter controller.

[0010] Furthermore, the pressure transmitter transmits the pressure signal of the process gas in the air intake main pipe to the pressure transmitter controller. When the pressure value of the process gas in the air intake main pipe is greater than 10 kPa, the pressure transmitter controller sends an opening command to the main pneumatic ball valve, the main pneumatic ball valve is in an open state, and the bypass pneumatic ball valve and the loop pneumatic ball valve are in a closed state; when the pressure value of the process gas in the air intake main pipe is between 8 and 10 kPa, the pressure transmitter controller sends an opening command to the bypass pneumatic ball valve and the loop pneumatic ball valve, the main pneumatic ball valve, the bypass pneumatic ball valve and the loop pneumatic ball valve are all in an open state; when the pressure value of the process gas in the air intake main pipe is less than 8 kPa, the pressure transmitter controller sends a closing command to the main pneumatic ball valve, the main pneumatic ball valve is in a closed state, and the bypass pneumatic ball valve and the loop pneumatic ball valve are in an open state.

[0011] Furthermore, the pneumatic reflux regulating valve PID pressure stabilization control unit includes a second pressure transmitter, a pneumatic regulating valve and a second pressure transmitter controller. The second pressure transmitter is cooperatively arranged on the mixed air intake pipe. A return air pipe is arranged between the air outlet pipe and the mixed air intake pipe. The pneumatic regulating valve is cooperatively arranged on the return air pipe. The second pressure transmitter and the pneumatic regulating valve are both electrically connected to the second pressure transmitter controller.

[0012] Furthermore, pressure transmitter 2 transmits the pressure signal of the process gas in the mixed air intake pipe to pressure transmitter controller 2. When the pressure value of the process gas in the mixed air intake pipe is greater than 5kPa, pressure transmitter controller 2 sends an adjustment instruction to the pneumatic control valve, and the pneumatic control valve reduces the opening; when the pressure value of the process gas in the mixed air intake pipe is less than 5kPa, pressure transmitter controller 2 sends an adjustment instruction to the pneumatic control valve, and the pneumatic control valve increases the opening; when the pressure value of the process gas in the mixed air intake pipe is equal to 5kPa, the pneumatic control valve maintains the opening unchanged.

[0013] Furthermore, the vacuum pump working fluid alarm and shutdown interlock control unit includes a flow transmitter and a flow alarm controller. The flow transmitter is arranged on the pipeline between the cooler and the liquid ring vacuum pump. The pipeline between the cooler and the liquid ring vacuum pump includes a liquid supply main pipe and a liquid supply branch pipe. The cooler, the liquid supply main pipe, the liquid supply branch pipe and the liquid ring vacuum pump are connected in sequence. The liquid ring vacuum pump is provided with a motor. The flow transmitter is arranged on the liquid supply main pipe. The flow transmitter and the motor are both electrically connected to the flow alarm controller.

[0014] Furthermore, the flow transmitter transmits the flow signal of the working fluid in the liquid supply main pipe to the flow alarm controller. When the flow rate of the working fluid in the liquid supply main pipe is ≤5m³ / h, the flow alarm controller triggers a low flow alarm; when the flow rate of the working fluid in the liquid supply main pipe is ≤2m³ / h, the flow alarm controller sends a shutdown command to the motor, and the liquid ring vacuum pump stops working.

[0015] Furthermore, the automatic control system of the vacuum pump unit includes two liquid ring vacuum pumps, both of which are equipped with motors, one end of the two liquid ring vacuum pumps are connected to a mixed air intake pipe through two air intake pipes, a pressure transmitter 2 is provided on the mixed air intake pipe, one end of the mixed air intake pipe is connected to an air intake main pipe and a return air pipe 1 respectively, a pressure transmitter 1 is provided on the air intake main pipe, a pneumatic regulating valve is provided on the return air pipe 1, the other ends of the two liquid ring vacuum pumps are connected to a gas-liquid separation tank, a liquid level transmitter is provided on the gas-liquid separation tank, an air outlet pipe and a liquid replenishment pipe are provided on the top of the gas-liquid separation tank, a liquid replenishment valve is provided on the liquid replenishment pipe, and an end of the return air pipe 1 away from the mixed air intake pipe is connected to the air outlet pipe; One side of the two liquid ring vacuum pumps is equipped with an atmospheric jet pump, and the atmospheric jet pump is equipped with a bypass pipe, a return air branch pipe and a connecting pipe. The bypass pipe is provided with a bypass pneumatic ball valve. The return air branch pipe is connected to the outlet pipe through the return air pipe 2. One end of the bypass pipe away from the atmospheric jet pump and one end of the connecting pipe away from the atmospheric jet pump are connected to the intake pipe, and the intake pipe is provided with a main pneumatic ball valve; A liquid inlet pipe is arranged at the bottom of the gas-liquid separation tank, and one end of the liquid inlet pipe away from the gas-liquid separation tank is connected to the cooler, and a liquid inlet bypass pipe is arranged on one side of the liquid inlet pipe, and a liquid supply main pipe is arranged on the side of the cooler away from the liquid inlet pipe, and a flow transmitter is arranged on the liquid supply main pipe, and the liquid supply main pipe is connected to two liquid ring vacuum pumps through two liquid supply branch pipes, and two liquid discharge branch pipes are arranged at the bottom of the two liquid ring vacuum pumps, and one end of the two liquid discharge branch pipes away from the liquid ring vacuum pump is connected to the liquid discharge pipe, and a liquid outlet pipe is arranged between the liquid discharge pipe and the gas-liquid separation tank, and an automatic liquid outlet pipe is arranged at the bottom of the gas-liquid separation tank, and the automatic liquid outlet pipe is connected to the liquid discharge pipe, and a liquid discharge valve is arranged on the automatic liquid outlet pipe; The liquid level transmitter, the liquid replenishing valve and the liquid drain valve are all electrically connected to the liquid level indicating control alarm; the pressure transmitter 1, the bypass pneumatic ball valve, the main pneumatic ball valve and the loop pneumatic ball valve are all electrically connected to the pressure transmitter controller 1; the pressure transmitter 2 and the pneumatic regulating valve are all electrically connected to the pressure transmitter controller 2; the flow transmitter and the motor are all electrically connected to the flow alarm controller.

[0016] The beneficial effects of the present invention are: The atmospheric jet pump works together with the liquid ring vacuum pump to expand the working range of the vacuum pump unit, increase the suction capacity of the vacuum pump unit, and ensure that the vacuum pump unit can operate efficiently under different pressure conditions; the atmospheric jet pump automatic switching control unit can monitor the load changes of the vacuum pump unit in real time, automatically control the switching state of the atmospheric jet pump, and improve the working stability of the vacuum pump unit; the gas-liquid separation tank automatic replenishment and drainage control unit can maintain the liquid level in the gas-liquid separation tank within a reasonable range, ensure the normal operation of the gas-liquid separation tank, and improve the operating reliability of the vacuum pump unit; the pneumatic reflux control valve PID voltage stabilization control unit can adjust the opening of the pneumatic control valve, which helps to maintain the pressure stability of the vacuum pump unit and reduce the impact of pressure fluctuations on the vacuum pump unit; the vacuum pump working fluid alarm and shutdown interlock control unit can monitor the flow of the liquid supply main to avoid damage to the liquid ring vacuum pump due to insufficient working fluid flow, extend the service life of the liquid ring vacuum pump, and reduce maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a partial structural schematic diagram of the gas-liquid separation tank, the gas outlet pipe, the liquid replenishment pipe, the liquid inlet pipe, the liquid inlet bypass pipe, the liquid discharge pipe, the liquid outlet pipe, the automatic liquid outlet pipe and the automatic liquid replenishment and discharge control unit of the gas-liquid separation tank in the present invention; Figure 3 It is a partial structural diagram of the atmospheric jet pump, the air intake pipe, the mixed air intake pipe, the air intake main pipe, the first air return pipe, the bypass pipe, the air return branch pipe, the connecting pipe, the second air return pipe and the automatic switching control unit of the atmospheric jet pump in the present invention; Figure 4 It is a partial structural schematic diagram of the air intake pipe, the mixed air intake pipe, the air intake main pipe, the air return pipe and the pneumatic reflux regulating valve PID pressure stabilizing control unit in the present invention; Figure 5 It is a partial structural diagram of the liquid ring vacuum pump, cooler, motor, liquid supply main pipe, liquid supply branch pipe, liquid discharge branch pipe and vacuum pump working liquid alarm and shutdown interlock control unit in the present invention; Figure 6 It is an interlocking logic diagram of the automatic liquid replenishment and drainage control unit of the gas-liquid separation tank in the present invention; Figure 7 It is an interlocking logic diagram of the automatic switching control unit of the atmospheric jet pump in the present invention; Figure 8 It is an interlocking logic diagram of the vacuum pump working fluid alarm and shutdown interlocking control unit in the present invention; In the figure: 1. Liquid ring vacuum pump; 2. Atmospheric jet pump; 3. Inlet pipe; 4. Gas-liquid separation tank; 5. Inlet main pipe; 6. Outlet pipe; 7. Liquid replenishment pipe; 8. Return pipe 1; 9. Bypass pipe; 10. Return branch pipe; 11. Connecting pipe; 12. Liquid inlet pipe; 13. Cooler; 14. Liquid inlet bypass pipe; 15. Liquid supply main pipe; 16. Liquid supply branch pipe; 17. Liquid discharge branch pipe; 18. Liquid discharge pipe; 19. Mixing inlet pipe; 20. Liquid discharge pipe; 21. Liquid level transmitter 1. Liquid supply valve; 2. Liquid discharge valve; 2. Liquid level indication control alarm; 2. Automatic liquid outlet pipe; 2. Pressure transmitter 1; 2. Bypass pneumatic ball valve; 2. Main pneumatic ball valve; 2. Loop pneumatic ball valve; 3. Pressure transmitter controller 1; 3. Return air pipe 2; 3. Pressure transmitter 2; 3. Pneumatic regulating valve; 3. Pressure transmitter controller 2; 3. Flow transmitter; 3. Flow alarm controller; 3. Motor. DETAILED DESCRIPTION

[0018] The present invention is specifically described and illustrated below in conjunction with embodiments.

[0019] Example 1 like Figure 1-5 As shown, the automatic control system of the vacuum pump unit comprises a liquid ring vacuum pump 1, which is respectively connected to an atmospheric jet pump 2 and a gas-liquid separation tank 4, and the gas-liquid separation tank 4 and a cooler 13 are connected to the liquid ring vacuum pump 1 in sequence, and the liquid ring vacuum pump 1 and the atmospheric jet pump 2 extract process gas from the outside through a pipeline, and the process gas is mixed with the working fluid in the liquid ring vacuum pump 1 and enters the gas-liquid separation tank 4 for gas-liquid separation, and the separated process gas returns to the liquid ring vacuum pump 1, and the separated working fluid is cooled by the cooler 13 and returns to the liquid ring vacuum pump 1; an atmospheric jet pump automatic switching control unit is arranged on the pipeline between the liquid ring vacuum pump 1 and the outside, and the atmospheric jet pump automatic switching control unit adjusts the suction degree of the atmospheric jet pump 2 and the liquid ring vacuum pump 1 according to the pressure of the external process gas; the gas-liquid separation A pneumatic reflux regulating valve PID voltage stabilization control unit is provided on the gas circuit between the separation tank 4 and the liquid ring vacuum pump 1, and the pneumatic reflux regulating valve PID voltage stabilization control unit adjusts the flow rate of the reflux gas according to the pressure of the gas entering the liquid ring vacuum pump 1; a vacuum pump working fluid alarm and shutdown interlock control unit is provided on the pipeline between the cooler 13 and the liquid ring vacuum pump 1, and the vacuum pump working fluid alarm and shutdown interlock control unit monitors the flow rate of the working fluid in the pipeline, and triggers an alarm and / or shuts down the liquid ring vacuum pump 1 when the flow rate is insufficient; a liquid replenishment and drainage pipeline is provided on the gas-liquid separation tank 4, and a gas-liquid separation tank automatic liquid replenishment and drainage control unit is provided on the liquid replenishment and drainage pipeline, and the gas-liquid separation tank automatic liquid replenishment and drainage control unit performs liquid replenishment or drainage operations on the gas-liquid separation tank 4 according to the liquid level of the working fluid in the gas-liquid separation tank 4.

[0020] The automatic liquid replenishment and drainage control unit of the gas-liquid separation tank includes a liquid level transmitter 21, a liquid replenishment valve 22, a liquid discharge valve 23 and a liquid level indication control alarm 24. The liquid level transmitter 21 is arranged on the gas-liquid separation tank 4. The top of the gas-liquid separation tank 4 is provided with an air outlet pipe 6 and a liquid replenishment pipe 7. The bottom of the gas-liquid separation tank 4 is provided with an automatic liquid outlet pipe 25 and a liquid inlet pipe 12. The liquid replenishment valve 22 is arranged on the liquid replenishment pipe 7. The liquid discharge valve 23 is arranged on the automatic liquid outlet pipe 25. The liquid level transmitter 21, the liquid replenishment valve 22 and the liquid discharge valve 23 are all electrically connected to the liquid level indication control alarm 24.

[0021] The liquid level transmitter 21 transmits the liquid level signal of the working liquid in the gas-liquid separation tank 4 to the liquid level indication control alarm 24. When the liquid level value of the working liquid in the gas-liquid separation tank 4 is ≤175mm, the liquid level indication control alarm 24 sends an opening command to the liquid replenishing valve 22. After a delay of 3 seconds, the liquid replenishing valve 22 opens and starts to replenish the working liquid. When the liquid level value of the working liquid in the gas-liquid separation tank 4 is ≥250mm, the liquid level indication control alarm 24 sends a closing command to the liquid replenishing valve 22, and the liquid replenishing valve 22 closes and stops replenishing the working liquid. When the liquid level value of the working liquid in the gas-liquid separation tank 4 is ≥325mm, the liquid level indication control alarm 24 sends a closing command to the liquid replenishing valve 22, and the liquid replenishing valve 22 closes and stops replenishing the working liquid. The control alarm 24 sends an opening command to the drain valve 23. After a delay of 3 seconds, the drain valve 23 opens, and the working fluid in the gas-liquid separation tank 4 begins to be discharged. When the liquid level value of the working fluid in the gas-liquid separation tank 4 is ≤250mm, the liquid level indication control alarm 24 sends a closing command to the drain valve 23, and the drain valve 23 is closed to stop discharging the working fluid; when the liquid level value of the working fluid in the gas-liquid separation tank 4 is ≤100mm, the liquid level indication control alarm 24 triggers a low liquid level alarm. When the liquid level value of the working fluid in the gas-liquid separation tank 4 is ≥400mm, the liquid level indication control alarm 24 triggers a high liquid level alarm.

[0022] The automatic switching control unit of the atmospheric jet pump includes a pressure transmitter 26, a bypass pneumatic ball valve 27, a main pneumatic ball valve 28, a loop pneumatic ball valve 29 and a pressure transmitter controller 30. The pressure transmitter 26 is arranged on the pipeline between the liquid ring vacuum pump 1 and the outside world. The pipeline between the liquid ring vacuum pump 1 and the outside world includes an intake pipe 3, a mixed intake pipe 19 and an intake main pipe 5. The liquid ring vacuum pump 1, the intake pipe 3, the mixed intake pipe 19 and the intake main pipe 5 are connected in sequence. The atmospheric jet pump 2 is respectively connected with a bypass pipe 9, a return air branch pipe 10 and a connecting pipe 11. The atmospheric jet pump 2 One end is connected to the intake pipe 3 through the bypass pipe 9, and the other end of the atmospheric jet pump 2 is connected to the intake pipe 3 through the connecting pipe 11. The pressure transmitter 26 is arranged on the intake main pipe 5, the bypass pneumatic ball valve 27 is arranged on the bypass pipe 9, the main pneumatic ball valve 28 is arranged on the intake pipe 3 and the main pneumatic ball valve 28 is located between the bypass pipe 9 and the connecting pipe 11, and the loop pneumatic ball valve 29 is arranged on the return air branch pipe 10. The pressure transmitter 26, the bypass pneumatic ball valve 27, the main pneumatic ball valve 28 and the loop pneumatic ball valve 29 are all electrically connected to the pressure transmitter controller 30.

[0023] The pressure transmitter 26 transmits the pressure signal of the process gas in the air intake pipe 5 to the pressure transmitter controller 30. When the pressure value of the process gas in the air intake pipe 5 is greater than 10 kPa, the pressure transmitter controller 30 sends an opening command to the main pneumatic ball valve 28, the main pneumatic ball valve 28 is in an open state, and the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 are in a closed state; when the pressure value of the process gas in the air intake pipe 5 is between 8 and 10 kPa, the pressure transmitter controller 30 sends an opening command to the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29, the main pneumatic ball valve 28, the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 are all in an open state; when the pressure value of the process gas in the air intake pipe 5 is less than 8 kPa, the pressure transmitter controller 30 sends a closing command to the main pneumatic ball valve 28, the main pneumatic ball valve 28 is in a closed state, and the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 are in an open state.

[0024] The pneumatic reflux regulating valve PID pressure stabilizing control unit includes a pressure transmitter 32, a pneumatic regulating valve 33 and a pressure transmitter controller 34. The pressure transmitter 32 is arranged on the mixed air intake pipe 19. A return air pipe 8 is arranged between the air outlet pipe 6 and the mixed air intake pipe 19. The pneumatic regulating valve 33 is arranged on the return air pipe 8. The pressure transmitter 32 and the pneumatic regulating valve 33 are both electrically connected to the pressure transmitter controller 34.

[0025] The pressure transmitter 2 32 transmits the pressure signal of the process gas in the mixed air intake pipe 19 to the pressure transmitter controller 2 34. When the pressure value of the process gas in the mixed air intake pipe 19 is greater than 5 kPa, the pressure transmitter controller 2 34 sends an adjustment instruction to the pneumatic control valve 33, and the pneumatic control valve 33 reduces the opening; when the pressure value of the process gas in the mixed air intake pipe 19 is less than 5 kPa, the pressure transmitter controller 2 34 sends an adjustment instruction to the pneumatic control valve 33, and the pneumatic control valve 33 increases the opening; when the pressure value of the process gas in the mixed air intake pipe 19 is 5 kPa, the pneumatic control valve 33 maintains the opening unchanged.

[0026] The vacuum pump working fluid alarm and shutdown interlock control unit includes a flow transmitter 35 and a flow alarm controller 36. The flow transmitter 35 is arranged on the pipeline between the cooler 13 and the liquid ring vacuum pump 1. The pipeline between the cooler 13 and the liquid ring vacuum pump 1 includes a liquid supply main pipe 15 and a liquid supply branch pipe 16. The cooler 13, the liquid supply main pipe 15, the liquid supply branch pipe 16 are connected to the liquid ring vacuum pump 1 in sequence. The liquid ring vacuum pump 1 is provided with a motor 37. The flow transmitter 35 is arranged on the liquid supply main pipe 15. The flow transmitter 35 and the motor 37 are both electrically connected to the flow alarm controller 36.

[0027] The flow transmitter 35 transmits the flow signal of the working fluid in the liquid supply main pipe 15 to the flow alarm controller 36. When the flow rate of the working fluid in the liquid supply main pipe 15 is ≤5m³ / h, the flow alarm controller 36 triggers a low flow alarm; when the flow rate of the working fluid in the liquid supply main pipe 15 is ≤2m³ / h, the flow alarm controller 36 sends a shutdown command to the motor 37, and the liquid ring vacuum pump 1 stops working.

[0028] The automatic control system of the vacuum pump unit includes two liquid ring vacuum pumps 1, and the two liquid ring vacuum pumps 1 are both provided with motors 37. One ends of the two liquid ring vacuum pumps 1 are connected to the mixed air intake pipe 19 through two air intake pipes 3, and the mixed air intake pipe 19 is provided with a pressure transmitter 232. One end of the mixed air intake pipe 19 is respectively connected to the air intake main pipe 5 and the return air pipe 8, and the air intake main pipe 5 is provided with a pressure transmitter 26. The return air pipe 8 is provided with a pneumatic regulating valve 33. The other ends of the two liquid ring vacuum pumps 1 are commonly connected to the gas-liquid separation tank 4, and the gas-liquid separation tank 4 is provided with a liquid level transmitter 21. The top of the gas-liquid separation tank 4 is provided with an air outlet pipe 6 and a liquid replenishing pipe 7, and the liquid replenishing pipe 7 is provided with a liquid replenishing valve 22. The end of the return air pipe 8 away from the mixed air intake pipe 19 is connected to the air outlet pipe 6; One side of the two liquid ring vacuum pumps 1 is equipped with an atmospheric jet pump 2, and the atmospheric jet pump 2 is equipped with a bypass pipe 9, a return air branch pipe 10 and a connecting pipe 11. The bypass pipe 9 is provided with a bypass pneumatic ball valve 27. The return air branch pipe 10 is connected to the outlet pipe 6 through the return air pipe 2 31. The end of the bypass pipe 9 away from the atmospheric jet pump 2 and the end of the connecting pipe 11 away from the atmospheric jet pump 2 are connected to the intake pipe 3, and the intake pipe 3 is provided with a main pneumatic ball valve 28; A liquid inlet pipe 12 is provided at the bottom of the gas-liquid separation tank 4, and one end of the liquid inlet pipe 12 away from the gas-liquid separation tank 4 is connected to a cooler 13, and a liquid inlet bypass pipe 14 is provided on one side of the liquid inlet pipe 12. A liquid supply main pipe 15 is provided on the side of the cooler 13 away from the liquid inlet pipe 12, and a flow transmitter 35 is provided on the liquid supply main pipe 15. The liquid supply main pipe 15 is connected to two liquid ring vacuum pumps 1 through two liquid supply branch pipes 16, and two liquid discharge branch pipes 17 are also provided at the bottom of the two liquid ring vacuum pumps 1, respectively. One end of the two liquid discharge branch pipes 17 away from the liquid ring vacuum pump 1 is commonly connected to a liquid discharge pipe 18, and a liquid outlet pipe 20 is provided between the liquid discharge pipe 18 and the gas-liquid separation tank 4. An automatic liquid outlet pipe 25 is provided at the bottom of the gas-liquid separation tank 4, and the automatic liquid outlet pipe 25 is connected to the liquid discharge pipe 18, and a liquid discharge valve 23 is provided on the automatic liquid outlet pipe 25; The liquid level transmitter 21, the liquid replenishing valve 22 and the liquid drain valve 23 are all electrically connected to the liquid level indicating control alarm 24; the pressure transmitter 1 26, the bypass pneumatic ball valve 27, the main pneumatic ball valve 28 and the loop pneumatic ball valve 29 are all electrically connected to the pressure transmitter controller 1 30; the pressure transmitter 2 32 and the pneumatic regulating valve 33 are all electrically connected to the pressure transmitter controller 2 34; the flow transmitter 35 and the motor 37 are all electrically connected to the flow alarm controller 36.

[0029] like Figure 6 As shown in the figure, It represents the AND gate. The logic rule of the AND gate is: the output signal is high only when all input signals are high; the output signal is low as long as one input signal is low. It represents NOT gate. The logic rule of NOT gate is: the output signal is the opposite state of the input signal, that is, when the input signal is high, the output signal is low; when the input signal is low, the output signal is high. Represents an OR gate. The logic rule of the OR gate is: as long as one of the input signals is high, the output signal is high; only when all the input signals are low, the output signal is low; AN means alarm; K1 represents relay K1, and K2 represents relay K2.

[0030] Liquid replenishment valve 22 controls: Opening condition: When the liquid level value of the working liquid in the gas-liquid separation tank 4 is ≤175mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indication control alarm 24, and the liquid level indication control alarm 24 outputs a high-level signal, which is converted into a physical action through the relay K1. The normally open contact of the relay K1 closes after a delay of 3 seconds after power-on, and controls the liquid replenishment valve 22 to open. The 3-second delay can prevent the liquid replenishment valve 22 from opening and closing frequently due to slight fluctuations in the liquid level, ensuring that the liquid replenishment valve 22 is activated only after the liquid level is stable, thereby improving system stability.

[0031] The delay characteristics of the normally open contact with power-on delay are as follows: the contact will close to trigger the subsequent logic only when the input high-level signal continues to reach the set delay value of 3 seconds; if the high-level signal turns to a low-level signal before 3 seconds, the delay timing will automatically return to zero, and the timing will restart when the signal returns to a high-level signal again. At the same time, once the signal turns to a low-level signal during the contact closure process, the contact will be disconnected immediately without additional waiting delay.

[0032] When the liquid level indication control alarm 24 triggers the refill valve 22 to open, the liquid level indication control alarm 24 forms a return mechanism for maintaining a high level until the liquid level of the working fluid in the gas-liquid separation tank 4 rises to the liquid level value set for closing the refill valve 22.

[0033] Closing condition: When the liquid level value of the working fluid in the gas-liquid separation tank 4 is ≥250mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indication control alarm 24, and the liquid level indication control alarm 24 inverts the signal through the NOT gate and outputs a low-level signal. The low-level signal output by the liquid level indication control alarm 24 under the closed condition and the high-level signal output by the liquid level indication control alarm 24 under the open condition are subjected to AND gate logic operation and continue to output a low-level signal. Relay K1 converts the low-level signal into a physical action, and the power-on delay normally open contact of relay K1 is disconnected, controlling the liquid replenishment valve 22 to close.

[0034] The supply voltage of the liquid replenishing valve 22 is 24 VDC. I1 is the valve position feedback signal of the liquid replenishing valve 22 , which is used to feedback the state of the liquid replenishing valve 22 itself.

[0035] Drain valve 23 control: Opening condition: When the liquid level of the working liquid in the gas-liquid separation tank 4 is ≥325mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indication control alarm 24, and the liquid level indication control alarm 24 outputs a high-level signal, which is converted into a physical action through the relay K2. The normally open contact of the relay K2 is closed after a delay of 3 seconds after power-on, and the drain valve 23 is controlled to open. The 3-second delay can prevent the drain valve 23 from opening and closing frequently due to slight fluctuations in the liquid level, ensuring that the drain valve 23 is activated only after the liquid level is stable, thereby improving system stability.

[0036] When the liquid level indicating control alarm 24 triggers the drain valve 23 to open, the liquid level indicating control alarm 24 forms a return mechanism for maintaining a high level until the liquid level of the working fluid in the gas-liquid separation tank 4 drops to the liquid level value set for closing the drain valve 23.

[0037] Closing condition: When the liquid level value of the working liquid in the gas-liquid separation tank 4 is ≤250mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indication control alarm 24, and the liquid level indication control alarm 24 inverts the signal through the NOT gate and outputs a low-level signal. The low-level signal output by the liquid level indication control alarm 24 under the closed condition and the high-level signal output by the liquid level indication control alarm 24 under the open condition are subjected to AND gate logic operation and continue to output a low-level signal. Relay K2 converts the low-level signal into a physical action, and the power-on delay normally open contact of relay K2 is disconnected, controlling the drain valve 23 to close.

[0038] The power supply voltage of the drain valve 23 is 24 VDC. I2 is the valve position feedback signal of the drain valve 23 , which is used to feedback the state of the drain valve 23 itself.

[0039] Liquid level alarm: When the liquid level value of the working liquid in the gas-liquid separation tank 4 is ≤100 mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indication control alarm 24, and the liquid level indication control alarm 24 sends an alarm signal.

[0040] When the liquid level of the working liquid in the gas-liquid separation tank 4 is ≥400 mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indication control alarm 24, and the liquid level indication control alarm 24 sends an alarm signal.

[0041] like Figure 7 As shown in the figure, It represents the AND gate. The logic rule of the AND gate is: the output signal is high only when all input signals are high; the output signal is low as long as one input signal is low. It represents the NOT gate. The logic rule of the NOT gate is that the output signal is the opposite state of the input signal. That is, when the input signal is high, the output signal is low; when the input signal is low, the output signal is high. Represents an OR gate. The logic rule of the OR gate is: as long as one of the input signals is high, the output signal is high; only when all the input signals are low, the output signal is low; AN means alarm; K1 represents relay K1, and K2 represents relay K2.

[0042] Bypass pneumatic ball valve 27 and loop pneumatic ball valve 29 control: When the liquid ring vacuum pump 1 is turned on, a high level signal is output; When the pressure transmitter 26 detects that the pressure value of the process gas in the intake main pipe 5 is greater than 10 kPa, the pressure transmitter 26 transmits the pressure signal to the pressure transmitter controller 30, and the pressure transmitter controller 30 inverts the signal through the NOT gate and outputs a low-level signal; the low-level signal output by the pressure transmitter controller 30 under the condition of pressure value greater than 10 kPa and the high-level signal output by the liquid ring vacuum pump 1 under the ON condition are subjected to AND gate logic operation, and continue to output a low-level signal, and the relay K1 receives the low-level signal to control the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 to close.

[0043] When the pressure transmitter 26 detects that the pressure value of the process gas in the intake main pipe 5 is ≤10kPa, the pressure transmitter 26 transmits the pressure signal to the pressure transmitter controller 30, and the pressure transmitter controller 30 inverts the signal through the NOT gate and outputs a high-level signal; after the high-level signal output by the pressure transmitter controller 30 under the condition of pressure value ≤10kPa and the high-level signal output by the liquid ring vacuum pump 1 under the ON condition undergoes AND gate logic operation, the high-level signal continues to be output, and the relay K1 receives the high-level signal to control the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 to open. When the pressure transmitter controller 30 triggers the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 to open, the pressure transmitter controller 30 forms a return mechanism to maintain the high-level signal and keep the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 open.

[0044] Main pneumatic ball valve 28 control: When the liquid ring vacuum pump 1 is turned on, a high level signal is output; When the pressure transmitter 26 detects that the pressure value of the process gas in the intake main pipe 5 is ≥8kPa, the pressure transmitter 26 transmits the pressure signal to the pressure transmitter controller 30, and the pressure transmitter controller 30 inverts the signal through the NOT gate and outputs a high-level signal; after the high-level signal output by the pressure transmitter controller 30 under the condition of pressure value ≥8kPa and the high-level signal output by the liquid ring vacuum pump 1 under the opening condition undergoes AND gate logic operation, the high-level signal continues to be output, and the relay K2 receives the high-level signal to control the main pneumatic ball valve 28 to open. When the pressure transmitter controller 30 triggers the main pneumatic ball valve 28 to open, the pressure transmitter controller 30 forms a return mechanism to maintain the high-level signal and keep the main pneumatic ball valve 28 open.

[0045] When the pressure transmitter 26 detects that the pressure value of the process gas in the intake main pipe 5 is less than 8 kPa, the pressure transmitter 26 transmits the pressure signal to the pressure transmitter controller 30, and the pressure transmitter controller 30 inverts the signal through the NOT gate and outputs a low-level signal; the low-level signal output by the pressure transmitter controller 30 under the condition of pressure value less than 8 kPa and the high-level signal output by the liquid ring vacuum pump 1 under the ON condition are subjected to AND gate logic operation, and continue to output a low-level signal, and the relay K2 receives the low-level signal to control the main pneumatic ball valve 28 to close.

[0046] The power supply voltage of the main pneumatic ball valve 28, the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 are all 24VDC. I1 is the valve position feedback signal of the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29, which is used to feedback the valve's own state. I2 is the valve position feedback signal of the main pneumatic ball valve 28, which is used to feedback the valve's own state.

[0047] like Figure 8 As shown, when the flow rate of the working fluid in the liquid supply main pipe 15 is ≤5m³ / h, the flow transmitter 35 transmits the flow signal to the flow alarm controller 36, and the flow alarm controller 36 sends an alarm signal.

[0048] When the flow rate of the working fluid in the liquid supply main pipe 15 is ≤2m³ / h, the flow transmitter 35 transmits the flow signal to the flow alarm controller 36, and the flow alarm controller 36 sends a stop command to the motor 37, and the liquid ring vacuum pump 1 stops working.

[0049] Working principle and process: Gas suction: Driven by the motor 37, the liquid ring vacuum pump 1 starts to operate, and extracts process gas from the outside through the intake pipe 3, the mixed intake pipe 19 and the intake main pipe 5. The atmospheric jet pump 2 works in coordination with the liquid ring vacuum pump 1, and the coordination mode of the two will be adjusted accordingly according to the pressure change in the intake main pipe 5. When the pressure transmitter 26 detects that the process gas pressure value in the intake main pipe 5 is greater than 10kPa, the main pneumatic ball valve 28 is opened, and the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 are closed. At this time, the gas suction operation is only carried out by the liquid ring vacuum pump 1. When the pressure transmitter 26 detects that the process gas pressure value in the intake pipe 5 is between 8kPa and 10kPa, the main pneumatic ball valve 28, the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 are all opened, the atmospheric jet pump 2 extracts the process gas through the bypass pipe 9, and the liquid ring vacuum pump 1 extracts the process gas through the intake pipe 3. The two extract the process gas from the outside at the same time. This parallel working mode increases the overall air extraction flow and improves the air extraction efficiency. When the pressure transmitter 26 detects that the process gas pressure value in the intake pipe 5 is less than 8kPa, the main pneumatic ball valve 28 is closed, the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 are opened, and the atmospheric jet pump 2 and the liquid ring vacuum pump 1 are connected in series to extract the process gas from the outside. The gas is first sucked by the atmospheric jet pump 2, and then sucked by the liquid ring vacuum pump 1 for the second time, ensuring that the vacuum pump unit can stably perform air extraction work even in a low-pressure environment.

[0050] Gas-liquid separation and liquid level control: After the extracted process gas enters the liquid ring vacuum pump 1, it mixes with the working fluid to form a mixed fluid, and is discharged into the gas-liquid separation tank 4 together. After the mixed fluid enters the gas-liquid separation tank 4, it is separated, the working fluid settles to the bottom of the gas-liquid separation tank 4, and the extracted process gas moves upward and is discharged from the gas-liquid separation tank 4. The liquid level transmitter 21 monitors the liquid level value of the working fluid in the gas-liquid separation tank 4 in real time. When the liquid level value is ≤175mm, the liquid level indication control alarm 24 controls the liquid replenishment valve 22 to open, and replenishes liquid from the liquid replenishment pipe 7 to the gas-liquid separation tank 4. When the liquid level value is ≥250mm, the liquid replenishment valve 22 is closed. When the liquid level value is ≥325mm, the drain valve 23 is opened, and the working fluid in the gas-liquid separation tank 4 is discharged through the automatic liquid outlet pipe 25. When the liquid level value is ≤250mm, the drain valve 23 is closed. When the liquid level value is ≤100mm or the liquid level value is ≥400mm, the liquid level indication control alarm 24 triggers the low liquid level alarm and the high liquid level alarm respectively, thereby maintaining the liquid level within a reasonable range and ensuring the normal operation of the gas-liquid separation tank 4.

[0051] Working fluid circulation and cooling: The working liquid at the bottom of the gas-liquid separation tank 4 flows into the cooler 13 through the liquid inlet pipe 12 for cooling, and the cooled working liquid returns to the liquid ring vacuum pump 1 through the liquid supply main pipe 15 and the liquid supply branch pipe 16. The drain branch pipe 17 collects the working liquid in the liquid ring vacuum pump 1 and discharges it through the drain pipe 18.

[0052] Pressure Regulation: The pressure transmitter 2 32 monitors the pressure value of the process gas in the mixed air inlet pipe 19 in real time. When the pressure value is detected to be greater than 5kPa, the pressure indication control 2 34 will issue a command to the pneumatic control valve 33 to reduce its opening. Since the pneumatic control valve 33 is installed on the return air pipe 18, one end of the return air pipe 8 is connected to the mixed air inlet pipe 19, and the other end of the return air pipe 8 is connected to the outlet pipe 6 at the top of the gas-liquid separation tank 4, the reduction in the opening of the pneumatic control valve 33 will lead to a reduction in the process gas flowing back from the outlet pipe 6 through the return air pipe 18 to the mixed air inlet pipe 19, thereby reducing the pressure of the process gas entering the mixed air inlet pipe 19, and avoiding excessive pressure from having an adverse effect on subsequent equipment. When the pressure value is less than 5kPa, the pressure indicating control 2 34 controls the pneumatic regulating valve 33 to increase the opening. At this time, the process gas flowing back from the outlet pipe 6 to the mixed air intake pipe 19 through the return pipe 1 8 increases, and more process gas returns to the mixed air intake pipe 19, thereby increasing the pressure of the process gas entering the mixed air intake pipe 19 to ensure that the pressure is within a suitable range. When the pressure value = 5kPa, the pressure indicating control 2 34 controls the pneumatic regulating valve 33 to keep the current opening unchanged, ensuring that the entire vacuum pump unit operates under stable pressure conditions.

[0053] Flow monitoring and protection: The flow transmitter 35 monitors the flow value of the working fluid in the liquid supply main pipe 15. When the flow value is ≤5m³ / h, the flow indication alarm controller 36 triggers a low flow alarm; when the flow value is ≤2m³ / h, the flow indication alarm controller 36 sends a shutdown command to the motor 37 to stop the liquid ring vacuum pump 1, thereby avoiding damage to the liquid ring vacuum pump 1 due to insufficient working fluid flow, extending the service life and reducing maintenance costs.

Claims

1. An automatic control system for a vacuum pump unit, comprising a liquid ring vacuum pump (1), wherein the liquid ring vacuum pump (1) is connected to an atmospheric jet pump (2) and a gas-liquid separation tank (4), respectively, and the gas-liquid separation tank (4) and a cooler (13) are connected to the liquid ring vacuum pump (1) in sequence, characterized in that: The liquid ring vacuum pump (1) and the atmospheric jet pump (2) extract process gas from the outside through pipelines. The process gas is mixed with the working fluid in the liquid ring vacuum pump (1) and enters the gas-liquid separation tank (4) for gas-liquid separation. The separated process gas returns to the liquid ring vacuum pump (1). The separated working fluid is cooled by a cooler (13) and then returns to the liquid ring vacuum pump (1). An atmospheric jet pump automatic switching control unit is arranged on the pipeline between the liquid ring vacuum pump (1) and the outside. The atmospheric jet pump automatic switching control unit adjusts the suction degree of the atmospheric jet pump (2) and the liquid ring vacuum pump (1) according to the pressure of the external process gas. A pneumatic reflux regulating valve PID is arranged on the gas circuit between the gas-liquid separation tank (4) and the liquid ring vacuum pump (1). A pressure regulating control unit, a pneumatic reflux regulating valve PID pressure regulating control unit regulates the flow of reflux gas according to the pressure of the gas entering the liquid ring vacuum pump (1); a vacuum pump working fluid alarm and shutdown interlock control unit is arranged on the pipeline between the cooler (13) and the liquid ring vacuum pump (1), the vacuum pump working fluid alarm and shutdown interlock control unit monitors the flow of working fluid in the pipeline, and triggers an alarm and / or shuts down the liquid ring vacuum pump (1) when the flow is insufficient; a gas-liquid separation tank (4) is provided with a liquid replenishment and drainage pipeline, and a gas-liquid separation tank automatic liquid replenishment and drainage control unit is arranged on the liquid replenishment and drainage pipeline, and the gas-liquid separation tank automatic liquid replenishment and drainage control unit performs liquid replenishment or drainage operations on the gas-liquid separation tank (4) according to the liquid level of the working fluid in the gas-liquid separation tank (4).

2. The automatic control system of the vacuum pump unit according to claim 1, characterized in that: The automatic liquid replenishment and drainage control unit of the gas-liquid separation tank comprises a liquid level transmitter (21), a liquid replenishment valve (22), a liquid drainage valve (23) and a liquid level indication control alarm (24). The liquid level transmitter (21) is arranged on the gas-liquid separation tank (4). The top of the gas-liquid separation tank (4) is provided with a gas outlet pipe (6) and a liquid replenishment pipe (7). The bottom of the gas-liquid separation tank (4) is provided with an automatic liquid outlet pipe (25) and a liquid inlet pipe (12). The liquid replenishment valve (22) is arranged on the liquid replenishment pipe (7). The liquid drainage valve (23) is arranged on the automatic liquid outlet pipe (25). The liquid level transmitter (21), the liquid replenishment valve (22) and the liquid drainage valve (23) are all electrically connected to the liquid level indication control alarm (24).

3. The automatic control system of the vacuum pump unit according to claim 2, characterized in that: The liquid level transmitter (21) transmits the liquid level signal of the working liquid in the gas-liquid separation tank (4) to the liquid level indication control alarm (24). When the liquid level value of the working liquid in the gas-liquid separation tank (4) is ≤175 mm, the liquid level indication control alarm (24) sends an opening command to the liquid replenishing valve (22). After a delay of 3 seconds, the liquid replenishing valve (22) opens and starts replenishing the working liquid. When the liquid level value of the working liquid in the gas-liquid separation tank (4) is ≥250 mm, the liquid level indication control alarm (24) sends a closing command to the liquid replenishing valve (22). The liquid replenishing valve (22) closes and stops replenishing the working liquid. When the liquid level value of the working liquid in the gas-liquid separation tank (4) is ≥325 mm, the liquid level indication control alarm (24) sends a closing command to the liquid replenishing valve (22). The liquid replenishing valve (22) closes and stops replenishing the working liquid. The control alarm (24) sends an opening command to the drain valve (23). After a delay of 3 seconds, the drain valve (23) opens and the working fluid in the gas-liquid separation tank (4) begins to be discharged. When the liquid level value of the working fluid in the gas-liquid separation tank (4) is ≤250 mm, the liquid level indication control alarm (24) sends a closing command to the drain valve (23). The drain valve (23) closes and the discharge of the working fluid stops. When the liquid level value of the working fluid in the gas-liquid separation tank (4) is ≤100 mm, the liquid level indication control alarm (24) triggers a low liquid level alarm. When the liquid level value of the working fluid in the gas-liquid separation tank (4) is ≥400 mm, the liquid level indication control alarm (24) triggers a high liquid level alarm.

4. The automatic control system of the vacuum pump unit according to claim 2, characterized in that: The automatic switching control unit of the atmospheric jet pump comprises a pressure transmitter (26), a bypass pneumatic ball valve (27), a main pneumatic ball valve (28), a loop pneumatic ball valve (29) and a pressure transmitter controller (30). The pressure transmitter (26) is arranged on a pipeline between the liquid ring vacuum pump (1) and the outside world. The pipeline between the liquid ring vacuum pump (1) and the outside world comprises an intake pipe (3), a mixed intake pipe (19) and an intake main pipe (5). The liquid ring vacuum pump (1), the intake pipe (3), the mixed intake pipe (19) and the intake main pipe (5) are connected in sequence. The atmospheric jet pump (2) is respectively connected with a bypass pipe (9), a return air branch pipe (10) and a connecting pipe (11). The atmospheric jet pump (2) The first end of the air pump (2) is connected to the air intake pipe (3) through a bypass pipe (9), and the other end of the atmospheric jet pump (2) is connected to the air intake pipe (3) through a connecting pipe (11). A pressure transmitter (26) is arranged on the air intake main pipe (5), a bypass pneumatic ball valve (27) is arranged on the bypass pipe (9), a main pneumatic ball valve (28) is arranged on the air intake pipe (3) and the main pneumatic ball valve (28) is located between the bypass pipe (9) and the connecting pipe (11), and a loop pneumatic ball valve (29) is arranged on the return air branch pipe (10). The pressure transmitter (26), the bypass pneumatic ball valve (27), the main pneumatic ball valve (28) and the loop pneumatic ball valve (29) are all electrically connected to a pressure transmitter controller (30).

5. The automatic control system of the vacuum pump unit according to claim 4, characterized in that: The pressure transmitter 1 (26) transmits the pressure signal of the process gas in the air inlet pipe (5) to the pressure transmitter controller 1 (30). When the pressure value of the process gas in the air inlet pipe (5) is greater than 10 kPa, the pressure transmitter controller 1 (30) sends an opening command to the main pneumatic ball valve (28). The main pneumatic ball valve (28) is in an open state, and the bypass pneumatic ball valve (27) and the loop pneumatic ball valve (29) are in a closed state. When the pressure value of the process gas in the air inlet pipe (5) is between 8 and 10 kPa, the pressure transmitter controller 1 (30) sends an opening command to the main pneumatic ball valve (28). The pressure transmitter controller 1 (30) sends an opening command to the bypass pneumatic ball valve (27) and the loop pneumatic ball valve (29), and the main pneumatic ball valve (28), the bypass pneumatic ball valve (27) and the loop pneumatic ball valve (29) are all in an open state; when the pressure value of the process gas in the air inlet main pipe (5) is less than 8 kPa, the pressure transmitter controller 1 (30) sends a closing command to the main pneumatic ball valve (28), and the main pneumatic ball valve (28) is in a closed state, and the bypass pneumatic ball valve (27) and the loop pneumatic ball valve (29) are in an open state.

6. The automatic control system of the vacuum pump unit according to claim 4, characterized in that: The pneumatic reflux regulating valve PID pressure stabilization control unit comprises a second pressure transmitter (32), a pneumatic regulating valve (33) and a second pressure transmitter controller (34). The second pressure transmitter (32) is arranged on the mixed air intake pipe (19). A first air return pipe (8) is arranged between the air outlet pipe (6) and the mixed air intake pipe (19). The pneumatic regulating valve (33) is arranged on the first air return pipe (8). The second pressure transmitter (32) and the pneumatic regulating valve (33) are both electrically connected to the second pressure transmitter controller (34).

7. The automatic control system of the vacuum pump unit according to claim 6, characterized in that: The second pressure transmitter (32) transmits a pressure signal of the process gas in the mixed air intake pipe (19) to the second pressure transmitter controller (34). When the pressure value of the process gas in the mixed air intake pipe (19) is greater than 5 kPa, the second pressure transmitter controller (34) sends a regulation instruction to the pneumatic control valve (33), and the pneumatic control valve (33) reduces its opening; when the pressure value of the process gas in the mixed air intake pipe (19) is less than 5 kPa, the second pressure transmitter controller (34) sends a regulation instruction to the pneumatic control valve (33), and the pneumatic control valve (33) increases its opening; when the pressure value of the process gas in the mixed air intake pipe (19) is equal to 5 kPa, the pneumatic control valve (33) maintains its opening unchanged.

8. The automatic control system of the vacuum pump unit according to claim 1, characterized in that: The vacuum pump working fluid alarm and shutdown interlock control unit comprises a flow transmitter (35) and a flow alarm controller (36). The flow transmitter (35) is arranged on a pipeline between a cooler (13) and a liquid ring vacuum pump (1). The pipeline between the cooler (13) and the liquid ring vacuum pump (1) comprises a liquid supply main pipe (15) and a liquid supply branch pipe (16). The cooler (13), the liquid supply main pipe (15), the liquid supply branch pipe (16) and the liquid ring vacuum pump (1) are connected in sequence. A motor (37) is arranged on the liquid ring vacuum pump (1). The flow transmitter (35) is arranged on the liquid supply main pipe (15). Both the flow transmitter (35) and the motor (37) are electrically connected to the flow alarm controller (36).

9. The automatic control system of the vacuum pump unit according to claim 8, characterized in that: The flow transmitter (35) transmits a flow signal of the working fluid in the liquid supply main pipe (15) to the flow alarm controller (36). When the flow rate of the working fluid in the liquid supply main pipe (15) is ≤5 m³ / h, the flow alarm controller (36) triggers a low flow alarm. When the flow rate of the working fluid in the liquid supply main pipe (15) is ≤2 m³ / h, the flow alarm controller (36) sends a stop command to the motor (37), and the liquid ring vacuum pump (1) stops working.

10. The automatic control system of the vacuum pump unit according to claim 1, characterized in that: The invention comprises two liquid ring vacuum pumps (1), each of which is provided with a motor (37), one end of each of the two liquid ring vacuum pumps (1) is connected to a mixed air intake pipe (19) through two air intake pipes (3), a second pressure transmitter (32) is provided on the mixed air intake pipe (19), one end of each of the mixed air intake pipes (19) is connected to an air intake main pipe (5) and an air return pipe (8), a pressure transmitter (26) is provided on the air intake main pipe (5), a pneumatic regulating valve (33) is provided on the air return pipe (8), the other ends of the two liquid ring vacuum pumps (1) are connected to a gas-liquid separation tank (4), a liquid level transmitter (21) is provided on the gas-liquid separation tank (4), an air outlet pipe (6) and a liquid replenishing pipe (7) are provided on the top of the gas-liquid separation tank (4), a liquid replenishing valve (22) is provided on the liquid replenishing pipe (7), and an end of the air return pipe (8) away from the mixed air intake pipe (19) is connected to the air outlet pipe (6); One side of each of the two liquid ring vacuum pumps (1) is provided with an atmospheric jet pump (2). The atmospheric jet pump (2) is provided with a bypass pipe (9), a return air branch pipe (10) and a connecting pipe (11). A bypass pneumatic ball valve (27) is provided on the bypass pipe (9). The return air branch pipe (10) is connected to the outlet pipe (6) through a second return air pipe (31). One end of the bypass pipe (9) away from the atmospheric jet pump (2) and one end of the connecting pipe (11) away from the atmospheric jet pump (2) are both connected to an intake pipe (3). A main pneumatic ball valve (28) is provided on the intake pipe (3). A liquid inlet pipe (12) is provided at the bottom of the gas-liquid separation tank (4); one end of the liquid inlet pipe (12) away from the gas-liquid separation tank (4) is connected to a cooler (13); a liquid inlet bypass pipe (14) is provided on one side of the liquid inlet pipe (12); a liquid supply main pipe (15) is provided on the side of the cooler (13) away from the liquid inlet pipe (12); a flow transmitter (35) is provided on the liquid supply main pipe (15); and the liquid supply main pipe (15) is connected to two liquid ring vacuum pumps (16) through two liquid supply branch pipes (16). 1), two liquid discharge branch pipes (17) are respectively provided at the bottom of the two liquid ring vacuum pumps (1), one end of the two liquid discharge branch pipes (17) away from the liquid ring vacuum pump (1) is connected to a liquid discharge pipe (18), a liquid outlet pipe (20) is provided between the liquid discharge pipe (18) and the gas-liquid separation tank (4), an automatic liquid outlet pipe (25) is provided at the bottom of the gas-liquid separation tank (4), the automatic liquid outlet pipe (25) is connected to the liquid discharge pipe (18), and a liquid discharge valve (23) is provided on the automatic liquid outlet pipe (25); The liquid level transmitter (21), the liquid replenishing valve (22) and the liquid drain valve (23) are all electrically connected to the liquid level indicating control alarm (24); the pressure transmitter 1 (26), the bypass pneumatic ball valve (27), the main pneumatic ball valve (28) and the loop pneumatic ball valve (29) are all electrically connected to the pressure transmitter controller 1 (30); the pressure transmitter 2 (32) and the pneumatic regulating valve (33) are all electrically connected to the pressure transmitter controller 2 (34); and the flow transmitter (35) and the motor (37) are all electrically connected to the flow alarm controller (36).

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