Automatic control system for vacuum pump unit

Abstract

The present invention belongs to the technical field of liquid variable volume machinery, and particularly relates to an automatic control system for a vacuum pump unit, which includes a liquid ring vacuum pump. The liquid ring vacuum pump is respectively connected to an air ejector pump and a gas-liquid separation tank. The gas-liquid separation tank, a cooler and the liquid ring vacuum pump are connected in sequence. An automatic switching control unit for the air ejector pump is arranged on the pipeline between the liquid ring vacuum pump and the outside. A PID voltage stabilizing control unit for a pneumatic return regulating valve is arranged on the gas return pipeline between the gas-liquid separation tank and the liquid ring vacuum pump. A warning and shutdown interlock control unit for the working liquid of the vacuum pump is arranged on the pipeline between the cooler and the liquid ring vacuum pump. A liquid supplement and discharge pipeline is arranged on the gas-liquid separation tank, and an automatic liquid supplement and discharge control unit for the gas-liquid separation tank is arranged on the liquid supplement and discharge pipeline. The present invention can quickly adjust various operating parameters of the vacuum pump unit under different working conditions to ensure the stable operation of the vacuum pump unit.

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:

[0007] The automatic control system of the vacuum pump unit described in the present invention includes a liquid ring vacuum pump, which is respectively connected to an air ejector pump and a gas-liquid separation tank. The gas-liquid separation tank, the cooler and the liquid ring vacuum pump are connected in sequence. The liquid ring vacuum pump and the air ejector pump extract process gas from the outside through pipelines. The process gas is mixed with the working liquid 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 liquid returns to the liquid ring vacuum pump after being cooled by the cooler. An automatic switching control unit for the air ejector pump is provided on the pipeline between the liquid ring vacuum pump and the outside. The automatic switching control unit for the air ejector pump adjusts the suction degree of the air ejector pump and the liquid ring vacuum pump according to the pressure of the outside process gas. A pneumatic return regulating valve PID voltage stabilizing control unit is provided on the gas return pipeline between the gas-liquid separation tank and the liquid ring vacuum pump. The pneumatic return regulating valve PID voltage stabilizing control unit adjusts the flow rate of the return gas according to the pressure of the gas entering the liquid ring vacuum pump. A vacuum pump working liquid alarm and shutdown interlock control unit is provided on the pipeline between the cooler and the liquid ring vacuum pump. The vacuum pump working liquid alarm and shutdown interlock control unit monitors the flow rate of the working liquid in the pipeline and triggers an alarm and / or shuts down the liquid ring vacuum pump when the flow rate is insufficient. A liquid supply and discharge pipeline is provided on the gas-liquid separation tank, and an automatic liquid supply and discharge control unit for the gas-liquid separation tank is provided on the liquid supply and discharge pipeline. The automatic liquid supply and discharge control unit for the gas-liquid separation tank performs liquid supply or liquid discharge operations on the gas-liquid separation tank according to the liquid level of the working liquid in the gas-liquid separation tank.

[0008] Further, the automatic liquid supply and discharge control unit for the gas-liquid separation tank includes a liquid level transmitter, a liquid supply valve, a liquid discharge 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 supply pipe are arranged at the top of the gas-liquid separation tank. An automatic liquid outlet pipe and a liquid inlet pipe are arranged at the bottom of the gas-liquid separation tank. The liquid supply valve is cooperatively arranged on the liquid supply pipe, and the liquid discharge valve is cooperatively arranged on the automatic liquid outlet pipe. The liquid level transmitter, the liquid supply valve and the liquid discharge valve are all electrically connected to the liquid level indication control alarm.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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;

[0017] 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;

[0018] 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;

[0019] 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.

[0020] The beneficial effects of the present invention are:

[0021] The air 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 the efficient operation of the vacuum pump unit under different pressure conditions; the automatic switching control unit of the air jet pump can monitor the load changes borne by the vacuum pump unit in real time, automatically control the switching state of the air jet pump, and improve the working stability of the vacuum pump unit; the automatic liquid supply and drainage control unit of the gas-liquid separation tank 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 operation reliability of the vacuum pump unit; the PID voltage stabilization control unit of the pneumatic return regulating valve can adjust the opening of the pneumatic regulating valve, help maintain the pressure stability of the vacuum pump unit, and reduce the impact of pressure fluctuations on the vacuum pump unit; the alarm and shutdown interlock control unit of the vacuum pump working fluid can monitor the flow rate of the liquid supply main pipe, avoid damage to the liquid ring vacuum pump due to insufficient working fluid flow rate, extend the service life of the liquid ring vacuum pump, and reduce the maintenance cost. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of the present invention;

[0023] Figure 2 is a partial structural diagram of the gas-liquid separation tank, the air outlet pipe, the liquid supply 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 supply and drainage control unit of the gas-liquid separation tank of the present invention;

[0024] Figure 3 is a partial structural diagram of the air jet pump, the air inlet pipe, the mixed air inlet pipe, the main air inlet pipe, the first return air pipe, the bypass pipe, the return air branch pipe, the connecting pipe, the second return air pipe and the automatic switching control unit of the air jet pump of the present invention;

[0025] Figure 4 is a partial structural diagram of the air inlet pipe, the mixed air inlet pipe, the main air inlet pipe, the first return air pipe and the PID voltage stabilization control unit of the pneumatic return regulating valve of the present invention;

[0026] Figure 5 is a partial structural diagram of the liquid ring vacuum pump, the cooler, the motor, the liquid supply main pipe, the liquid supply branch pipe, the liquid discharge branch pipe and the alarm and shutdown interlock control unit of the vacuum pump working fluid of the present invention;

[0027] Figure 6 is the interlock logic diagram of the automatic liquid supply and drainage control unit of the gas-liquid separation tank of the present invention;

[0028] Figure 7 is the interlock logic diagram of the automatic switching control unit of the air jet pump of the present invention;

[0029] Figure 8 is the interlock logic diagram of the alarm and shutdown interlock control unit of the vacuum pump working fluid of the present invention;

[0030] In the figure:

[0031] 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

[0032] The present invention is specifically described and illustrated below in conjunction with embodiments.

[0033] Example 1

[0034] 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.

[0035] 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 drainage valve 23, and a liquid level indicating control alarm 24. The liquid level transmitter 21 is arranged in cooperation on the gas-liquid separation tank 4. An air outlet pipe 6 and a liquid replenishment pipe 7 are arranged at the top of the gas-liquid separation tank 4. An automatic liquid outlet pipe 25 and a liquid inlet pipe 12 are arranged at the bottom of the gas-liquid separation tank 4. The liquid replenishment valve 22 is arranged in cooperation on the liquid replenishment pipe 7. The liquid drainage valve 23 is arranged in cooperation 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 indicating control alarm 24.

[0036] 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 indicating control alarm 24. When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≤ 175 mm, the liquid level indicating control alarm 24 sends an opening instruction to the liquid replenishment valve 22. After a delay of 3 seconds, the liquid replenishment valve 22 opens to start replenishing the working liquid. When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≥ 250 mm, the liquid level indicating control alarm 24 sends a closing instruction to the liquid replenishment valve 22, and the liquid replenishment valve 22 closes to stop replenishing the working liquid; when the liquid level value of the working liquid in the gas-liquid separation tank 4 ≥ 325 mm, the liquid level indicating control alarm 24 sends an opening instruction to the liquid drainage valve 23. After a delay of 3 seconds, the liquid drainage valve 23 opens, and the working liquid in the gas-liquid separation tank 4 starts to be discharged. When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≤ 250 mm, the liquid level indicating control alarm 24 sends a closing instruction to the liquid drainage valve 23, and the liquid drainage valve 23 closes to stop discharging the working liquid; when the liquid level value of the working liquid in the gas-liquid separation tank 4 ≤ 100 mm, the liquid level indicating control alarm 24 triggers a low liquid level alarm. When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≥ 400 mm, the liquid level indicating control alarm 24 triggers a high liquid level alarm.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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;

[0044] 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;

[0045] 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;

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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;

[0050] AN means alarm;

[0051] K1 represents relay K1, and K2 represents relay K2.

[0052] Control of the liquid replenishing valve 22:

[0053] Opening condition: When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≤ 175 mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indicating control alarm 24. The liquid level indicating control alarm 24 outputs a high-level signal, which is converted into a physical action through relay K1. The normally open timed closing contact of relay K1 closes after a 3-second delay after being powered on, controlling the opening of the liquid replenishing valve 22. The 3-second delay can prevent the liquid replenishing valve 22 from opening and closing frequently due to small fluctuations in the liquid level, ensuring that the liquid replenishing valve 22 only executes actions after the liquid level is stable and improving the system stability.

[0054] The delay characteristic of the normally open timed closing contact is as follows: Only when the input high-level signal continuously reaches the set delay value of 3 seconds, the contact will close to trigger the subsequent logic; if the high-level signal turns into a low-level signal before 3 seconds, the delay timing will automatically return to zero, and it needs to wait until the signal returns to the high-level signal again to start timing. At the same time, once the signal turns into a low-level signal during the closing process of the contact, the contact will immediately disconnect without additional waiting for the delay.

[0055] When the liquid level indicating control alarm 24 triggers the opening of the liquid replenishing valve 22, the liquid level indicating control alarm 24 forms a feedback mechanism to maintain the high level until the liquid level of the working liquid in the gas-liquid separation tank 4 rises to the liquid level value set for closing the liquid replenishing valve 22.

[0056] Closing condition: When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≥ 250 mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indicating control alarm 24. The liquid level indicating control alarm 24 inverts the signal through a NOT gate and outputs a low-level signal. After the low-level signal output by the liquid level indicating control alarm 24 under the closing condition and the high-level signal output by the liquid level indicating control alarm 24 under the opening condition undergo an AND gate logic operation, a low-level signal is still output. Relay K1 converts the low-level signal into a physical action, and the normally open timed closing contact of relay K1 disconnects, controlling the closing of the liquid replenishing valve 22.

[0057] The supply voltage of the liquid replenishing valve 22 is 24 VDC, and I1 is the valve position feedback signal of the liquid replenishing valve 22, which is used to feedback the self-state of the liquid replenishing valve 22.

[0058] Control of the liquid discharge valve 23:

[0059] Opening condition: When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≥ 325 mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indicating control alarm 24. The liquid level indicating 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 power-on delay of the relay K2 closes after a 3-second delay after power-on, controlling the opening of the drain valve 23. The 3-second delay can prevent the drain valve 23 from opening and closing frequently due to small fluctuations in the liquid level, ensuring that the drain valve 23 only executes the action after the liquid level is stable, and improving the system stability.

[0060] When the liquid level indicating control alarm 24 triggers the opening of the drain valve 23, the liquid level indicating control alarm 24 forms a return mechanism to maintain the high level until the liquid level of the working liquid in the gas-liquid separation tank 4 drops to the liquid level value set for closing the drain valve 23.

[0061] Closing condition: When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≤ 250 mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indicating control alarm 24. The liquid level indicating 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 indicating control alarm 24 under the closing condition and the high-level signal output by the liquid level indicating control alarm 24 under the opening condition are subjected to AND gate logic operation, and then continue to output a low-level signal. The relay K2 converts the low-level signal into a physical action, and the normally open contact of the power-on delay of the relay K2 disconnects, controlling the closing of the drain valve 23.

[0062] The supply voltage of the drain valve 23 is 24 VDC, and I2 is the valve position feedback signal of the drain valve 23, which is used to feedback the self-state of the drain valve 23.

[0063] Liquid level alarm:

[0064] When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≤ 100 mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indicating control alarm 24, and the liquid level indicating control alarm 24 issues an alarm signal.

[0065] When the liquid level value of the working liquid in the gas-liquid separation tank 4 ≥ 400 mm, the liquid level transmitter 21 transmits the liquid level signal to the liquid level indicating control alarm 24, and the liquid level indicating control alarm 24 issues an alarm signal.

[0066] As Figure 7 shown in the figure, represents an AND gate. The logic rule of the AND gate is: only when all input signals are high level, the output signal is high level; as long as one input signal is low level, the output signal is low level;

[0067] 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.

[0068] 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;

[0069] AN means alarm;

[0070] K1 represents relay K1, and K2 represents relay K2.

[0071] Bypass pneumatic ball valve 27 and loop pneumatic ball valve 29 control:

[0072] When the liquid ring vacuum pump 1 is turned on, a high level signal is output;

[0073] 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.

[0074] 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.

[0075] Main pneumatic ball valve 28 control:

[0076] When the liquid ring vacuum pump 1 is turned on, a high level signal is output;

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] Working principle and process:

[0083] Gas suction:

[0084] 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 main intake pipe 5. The atmospheric jet pump 2 works in coordination with the liquid ring vacuum pump 1, and their cooperation mode will be adjusted accordingly based on the pressure change in the main intake pipe 5. When the pressure transmitter 1 - 26 detects that the process gas pressure value in the main intake pipe 5 > 10 kPa, the main pneumatic ball valve 28 opens, and the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 close. At this time, only the liquid ring vacuum pump 1 is used for gas suction operation. When the pressure transmitter 1 - 26 detects that the process gas pressure value in the main intake pipe 5 is between 8 kPa and 10 kPa, the main pneumatic ball valve 28, the bypass pneumatic ball valve 27, and the loop pneumatic ball valve 29 all open. The atmospheric jet pump 2 extracts process gas through the bypass pipe 9, and the liquid ring vacuum pump 1 extracts process gas through the intake pipe 3. The two simultaneously extract process gas from the outside. This parallel working method increases the overall pumping flow rate and improves the pumping efficiency. When the pressure transmitter 1 - 26 detects that the process gas pressure value in the main intake pipe 5 < 8 kPa, the main pneumatic ball valve 28 closes, and the bypass pneumatic ball valve 27 and the loop pneumatic ball valve 29 open. The atmospheric jet pump 2 and the liquid ring vacuum pump 1 extract process gas from the outside in series. The gas is first sucked by the atmospheric jet pump 2 and then secondarily sucked by the liquid ring vacuum pump 1 to ensure that the vacuum pump unit can stably perform the pumping work in a low - pressure environment.

[0085] Gas - liquid separation and liquid level control:

[0086] After the extracted process gas enters the liquid ring vacuum pump 1, it mixes with the working liquid to form a mixed fluid, which is then discharged into the gas - liquid separation tank 4 together. After the mixed fluid enters the gas - liquid separation tank 4, it separates. The working liquid settles to the bottom of the gas - liquid separation tank 4, and the extracted process gas moves upward and discharges from the gas - liquid separation tank 4. The liquid level transmitter 21 monitors the liquid level value of the working liquid in the gas - liquid separation tank 4 in real - time. When the liquid level value ≤ 175 mm, the liquid level indicating control alarm 24 controls the liquid filling valve 22 to open, and fills the gas - liquid separation tank 4 with liquid from the liquid filling pipe 7. When the liquid level value ≥ 250 mm, the liquid filling valve 22 closes. When the liquid level value ≥ 325 mm, the drain valve 23 opens, and the working liquid in the gas - liquid separation tank 4 is discharged through the automatic liquid discharge pipe 25. When the liquid level value ≤ 250 mm, the drain valve 23 closes. When the liquid level value ≤ 100 mm or the liquid level value ≥ 400 mm, the liquid level indicating control alarm 24 triggers low - level and high - level alarms respectively, so as to maintain the liquid level within a reasonable range and ensure the normal operation of the gas - liquid separation tank 4.

[0087] Working liquid circulation and cooling:

[0088] The working fluid at the bottom of the gas-liquid separation tank 4 flows into the cooler 13 through the liquid inlet pipe 12, and the cooled working fluid returns to the liquid ring vacuum pump 1 through the main liquid supply pipe 15 and the liquid supply branch pipe 16. The drain branch pipe 17 collects the working fluid in the liquid ring vacuum pump 1 and discharges it through the drain pipe 18.

[0089] Pressure regulation:

[0090] The pressure transmitter II 32 monitors the pressure value of the process gas in the mixed intake pipe 19 in real time. When the detected pressure value > 5 kPa, the pressure indicating controller II 34 will send an instruction to the pneumatic control valve 33 to reduce its opening. Since the pneumatic control valve 33 is installed on the first return pipe 8, one end of the first return pipe 8 is connected to the mixed intake pipe 19, and the other end of the first return pipe 8 is connected to the gas outlet pipe 6 at the top of the gas-liquid separation tank 4. The reduction of the opening of the pneumatic control valve 33 will cause the process gas flowing back from the gas outlet pipe 6 through the first return pipe 8 to the mixed intake pipe 19 to decrease, thereby reducing the pressure of the process gas entering the mixed intake pipe 19 and avoiding adverse effects on subsequent equipment caused by excessive pressure. When the pressure value < 5 kPa, the pressure indicating controller II 34 controls the pneumatic control valve 33 to increase its opening. At this time, the process gas flowing back from the gas outlet pipe 6 through the first return pipe 8 to the mixed intake pipe 19 increases, and more process gas returns to the mixed intake pipe 19, thereby increasing the pressure of the process gas entering the mixed intake pipe 19 and ensuring that the pressure is within a suitable range. When the pressure value = 5 kPa, the pressure indicating controller II 34 will control the pneumatic control valve 33 to maintain the current opening unchanged, ensuring that the entire vacuum pump unit operates under stable pressure conditions.

[0091] Flow monitoring and protection:

[0092] The flow transmitter 35 monitors the flow value of the working fluid in the main liquid supply pipe 15. When the flow value ≤ 5 m³ / h, the flow indicating alarm controller 36 triggers a low-flow alarm; when the flow value ≤ 2 m³ / h, the flow indicating alarm controller 36 sends a shutdown instruction to the motor 37 to stop the operation of the liquid ring vacuum pump 1, avoiding damage to the liquid ring vacuum pump 1 due to insufficient working fluid flow, extending its service life, and reducing maintenance costs.

Claims

1. An automatic control system for a vacuum pump unit, including a liquid ring vacuum pump (1), the liquid ring vacuum pump (1) is respectively connected to an air jet pump (2) and a gas-liquid separation tank (4), the gas-liquid separation tank (4) and a cooler (13) are sequentially connected to the liquid ring vacuum pump (1), and it is 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); 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).

2. The automatic control system for 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 includes 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). An air outlet pipe (6) and a liquid replenishment pipe (7) are arranged at the top of the gas-liquid separation tank (4). An automatic liquid outlet pipe (25) and a liquid inlet pipe (12) are arranged at the bottom of the gas-liquid separation tank (4). The liquid replenishment valve (22) is arranged on the liquid replenishment pipe (7), and 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) ≤ 175 mm, the liquid level indication control alarm (24) sends an opening instruction to the liquid replenishment valve (22). After a delay of 3 seconds, the liquid replenishment valve (22) opens to start replenishing the working liquid. When the liquid level value of the working liquid in the gas-liquid separation tank (4) ≥ 250 mm, the liquid level indication control alarm (24) sends a closing instruction to the liquid replenishment valve (22), and the liquid replenishment valve (22) closes to stop replenishing the working liquid. When the liquid level value of the working liquid in the gas-liquid separation tank (4) ≥ 325 mm, the liquid level indication control alarm (24) sends an opening instruction to the liquid drainage valve (23). After a delay of 3 seconds, the liquid drainage valve (23) opens, and the working liquid in the gas-liquid separation tank (4) starts to be discharged. When the liquid level value of the working liquid in the gas-liquid separation tank (4) ≤ 250 mm, the liquid level indication control alarm (24) sends a closing instruction to the liquid drainage valve (23), and the liquid drainage valve (23) closes to stop discharging the working liquid. When the liquid level value of the working liquid in the gas-liquid separation tank (4) ≤ 100 mm, the liquid level indication control alarm (24) triggers a low liquid level alarm. When the liquid level value of the working liquid in the gas-liquid separation tank (4) ≥ 400 mm, the liquid level indication control alarm (24) triggers a high liquid level alarm.

4. The automatic control system for a vacuum pump unit according to claim 1, 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.

5. The automatic control system of the vacuum pump unit according to claim 2, wherein 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).

6. The automatic control system of the vacuum pump unit according to claim 5, 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.

7. 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).

8. The automatic control system for a vacuum pump unit according to claim 7, characterized in that, The flow transmitter (35) transmits the flow signal of the working fluid in the main liquid supply pipe (15) to the flow alarm controller (36). When the flow of the working fluid in the main liquid supply pipe (15) ≤ 5 m³ / h, the flow alarm controller (36) triggers a low-flow alarm; when the flow of the working fluid in the main liquid supply pipe (15) ≤ 2 m³ / h, the flow alarm controller (36) issues a shutdown instruction to the motor (37), and the liquid ring vacuum pump (1) stops working.

9. The automatic control system for a vacuum pump unit according to claim 1, wherein It includes two liquid ring vacuum pumps (1), and motors (37) are arranged in cooperation with both of the two liquid ring vacuum pumps (1). One ends of the two liquid ring vacuum pumps (1) are respectively connected to the mixing inlet pipe (19) through two inlet pipes (3). A second pressure transmitter (32) is arranged on the mixing inlet pipe (19). One end of the mixing inlet pipe (19) is respectively connected to the main inlet pipe (5) and the first return pipe (8). A first pressure transmitter (26) is arranged on the main inlet pipe (5). A pneumatic control valve (33) is arranged on the first return pipe (8). The other ends of the two liquid ring vacuum pumps (1) are jointly connected to the gas-liquid separation tank (4). A liquid level transmitter (21) is arranged in cooperation with the gas-liquid separation tank (4). An outlet pipe (6) and a liquid supply pipe (7) are arranged at the top of the gas-liquid separation tank (4). A liquid supply valve (22) is arranged on the liquid supply pipe (7). The end of the first return pipe (8) far from the mixing inlet pipe (19) is connected to the outlet pipe (6); At one side of both of the two liquid ring vacuum pumps (1), an ejector pump (2) is arranged in cooperation. A bypass pipe (9), a return air branch pipe (10) and a connecting pipe (11) are arranged in cooperation with the ejector pump (2). A bypass pneumatic ball valve (27) is arranged on the bypass pipe (9). The return air branch pipe (10) is connected to the outlet pipe (6) through a second return pipe (31). One end of the bypass pipe (9) far from the ejector pump (2) and one end of the connecting pipe (11) far from the ejector pump (2) are both connected to the inlet pipe (3). A main path pneumatic ball valve (28) is arranged on the inlet pipe (3); An inlet pipe (12) is arranged at the bottom of the gas-liquid separation tank (4). The end of the inlet pipe (12) far from the gas-liquid separation tank (4) is connected to the cooler (13). A liquid supply bypass pipe (14) is arranged in cooperation with one side of the inlet pipe (12). A main liquid supply pipe (15) is arranged on the side of the cooler (13) far from the inlet pipe (12). A flow transmitter (35) is arranged on the main liquid supply pipe (15). The main liquid supply pipe (15) is respectively connected to the two liquid ring vacuum pumps (1) through two liquid supply branch pipes (16). Two drain branch pipes (17) are respectively arranged at the bottoms of the two liquid ring vacuum pumps (1). The ends of the two drain branch pipes (17) far from the liquid ring vacuum pumps (1) are jointly connected to a drain pipe (18). A liquid outlet pipe (20) is arranged in cooperation between the drain pipe (18) and the gas-liquid separation tank (4). An automatic liquid outlet pipe (25) is arranged at the bottom of the gas-liquid separation tank (4). The automatic liquid outlet pipe (25) is connected to the drain pipe (18). A drain valve (23) is arranged 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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