Vacuum pump unit and control method thereof

Abstract

The invention provides a vacuum pump unit. The vacuum pump unit comprises a control device, a nitrogen purging device, a vacuum main pipeline, a vacuum switching device, a roots vacuum pump device and a liquid ring vacuum pump device, a three-way valve and a roots pump vacuum bypass are further arranged at the ends, close to the roots vacuum pump device, of the vacuum main pipeline and the vacuum switching device, the roots pump vacuum bypass is communicated with the liquid ring vacuum pump device, and the vacuum main pipeline is alternatively communicated with the roots pump vacuum bypass or the roots vacuum pump device. And the control device is respectively connected with the nitrogen purging device, the vacuum main pipeline and vacuum switching device, the roots vacuum pump, the liquid ring vacuum pump device and the three-way valve. The problems that in the starting and stopping process of an existing vacuum pump unit, the operation process is tedious, errors are prone to occurring in operation, and the automation level is low are solved, automatic operation of the vacuum pump unit is achieved, and production efficiency is improved. In addition, operation safety can be guaranteed, and the method is particularly suitable for the situation involving dangerous chemicals.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum environment, and specifically relates to a vacuum pump unit. In addition, the present invention also relates to a control method of the vacuum pump unit. Background Art

[0002] The production of APIs often involves vacuum environments, such as vacuum concentration, vacuum distillation, vacuum crystallization, vacuum drying and other production processes. The establishment of a vacuum environment requires a vacuum device. For a high vacuum environment, such as a vacuum degree of 300Pa, a multi-stage vacuum pump combination is often required, such as a liquid ring Roots vacuum pump unit.

[0003] There are generally many instruments and valves in a vacuum pump unit. If the operational limitations of the process are considered at the same time, the start and stop of the vacuum pump unit generally requires a more complicated operation process. At present, vacuum pump units generally use manual or semi-automatic operation methods, that is, manually operate the instruments, valves and vacuum pumps in sequence to start and stop the unit. There are problems such as cumbersome operation process, easy operation errors, and low automation level. In particular, for highly dangerous chemicals such as ethylene oxide, it is necessary to strictly prevent them from entering the Roots pump or accumulating in pipelines and equipment. In addition, multiple valve operations need to be controlled during the start and stop process. Once the operator makes an error in operation, it will cause very serious consequences. Therefore, it is also very important to ensure operational safety.

[0004] In view of this, developing a vacuum pump unit that is easy to operate and can ensure safe operation has become an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art and to propose a vacuum pump unit to realize the automated operation of the vacuum pump unit. On the one hand, it can improve production efficiency and liberate manpower, and on the other hand, it can ensure operational safety, and is particularly suitable for working conditions involving hazardous chemicals.

[0006] The present invention is achieved through the following technical solutions:

[0007] One of the inventive objectives of the present invention is to provide a vacuum pump unit, comprising a control device and a nitrogen purge device, a vacuum main line and a vacuum switching device, a Roots vacuum pump device, and a liquid ring vacuum pump device connected in sequence; the vacuum main line and the vacuum switching device are also provided with a three-way valve and a Roots pump vacuum bypass at one end close to the Roots vacuum pump device, the Roots pump vacuum bypass is connected to the liquid ring vacuum pump device, and the vacuum main line is selectively connected to the Roots pump vacuum bypass or the Roots vacuum pump device; the control device is respectively connected to the nitrogen purge device, the vacuum main line and the vacuum switching device, the Roots vacuum pump, the liquid ring vacuum pump device, and the three-way valve.

[0008] In a preferred embodiment of the present invention, the control device comprises

[0009] The key module is configured to receive start, stop, high vacuum start, high vacuum stop, emergency stop, and liquid level operation control instructions and send them to the controller; on the other hand, it is configured to receive a stop instruction and send it to the judgment module;

[0010] A judgment module, which is configured to receive a shutdown command sent by the key module, judge a high vacuum state, and send the high vacuum state to a controller;

[0011] The controller is configured to receive the high vacuum state sent by the judgment module on the one hand, and to control the nitrogen purge device, the vacuum main line and the vacuum switching device, the Roots vacuum pump, the liquid ring vacuum pump device, and the three-way valve in response to the instructions sent by the key module on the other hand.

[0012] In a preferred embodiment of the present invention,

[0013] The liquid ring vacuum pump device is provided with a buffer tank, and a buffer tank liquid level transmitter is provided on the side wall of the buffer tank;

[0014] The buffer tank is provided with a fresh working fluid inlet pipeline, and one end of the fresh working fluid inlet pipeline arranged in the buffer tank is provided with a working fluid inlet float valve;

[0015] The control device is connected to the buffer tank liquid level transmitter and the working fluid inlet float valve.

[0016] In a preferred embodiment of the present invention, a buffer tank overflow pipeline is provided on the side wall of the buffer tank.

[0017] In a preferred embodiment of the present invention, the buffer tank overflow pipeline is provided with a U-shaped bend.

[0018] In a preferred embodiment of the present invention, the vacuum pump unit further comprises a post-pump condensation device connected to the liquid ring vacuum pump device.

[0019] In a preferred embodiment of the present invention, the post-pump condensation device is provided with a condenser outlet pipeline, on which a condenser outlet temperature transmitter is provided.

[0020] In a preferred embodiment of the present invention, the vacuum pump unit further comprises a vacuum return line and a vacuum exhaust device, which are connected to the post-pump condensing device.

[0021] The second object of the present invention is to provide a control method for a vacuum pump unit, comprising:

[0022] If a start command is received, the following operations are performed: the liquid ring vacuum pump is controlled to start; after the liquid ring vacuum pump runs for 10 seconds, the vacuum cut-off valve is controlled to open;

[0023] If a high vacuum start command is received, the following operations are performed: the three-way valve is controlled to switch from the Roots pump vacuum bypass to the Roots pump inlet pipeline; the Roots vacuum pump is controlled to start after 5 seconds;

[0024] If a high vacuum stop command is received, the following operations are performed: the vacuum shut-off valve is controlled to close; after 5 seconds, the Roots vacuum pump is controlled to close and the nitrogen shut-off valve is controlled to open to purge the Roots vacuum pump; after the purge time reaches the purge time threshold, the nitrogen shut-off valve is controlled to close and the three-way valve is controlled to switch from the Roots pump inlet pipeline to the Roots pump vacuum bypass; after 5 seconds, the vacuum shut-off valve is controlled to open;

[0025] If a shutdown command and a high vacuum opening state sent by the judgment module are received, the following operations are performed: the vacuum shut-off valve is controlled to be closed; after 5 seconds, the Roots vacuum pump is controlled to be closed and the nitrogen shut-off valve is controlled to be opened at the same time; after the purge time reaches the purge time threshold, the three-way valve is controlled to switch from the Roots pump inlet pipeline to the Roots pump vacuum bypass; after the liquid ring vacuum pump reaches the operating time threshold, the nitrogen shut-off valve is controlled to be closed and the liquid ring vacuum pump is controlled to be closed at the same time;

[0026] If a shutdown command and a high vacuum shutdown state sent by the judgment module are received, the following operations are performed: the vacuum shut-off valve is controlled to be closed; the nitrogen shut-off valve is controlled to be opened after 5 seconds; after the liquid ring vacuum pump reaches the operating time threshold, the nitrogen shut-off valve is controlled to be closed, and the liquid ring vacuum pump is controlled to be closed at the same time;

[0027] If an emergency stop command is received, the following operations are performed: control the vacuum cut-off valve to close, control the three-way valve to switch from the Roots pump inlet pipeline to the Roots pump vacuum bypass, and control the Roots vacuum pump and liquid ring vacuum pump to close.

[0028] In a preferred embodiment of the present invention, the control method of the vacuum pump unit further includes:

[0029] If a liquid level operation control instruction is received, the following operations are performed: if the real-time liquid level is lower than the low liquid level setting value in the preset liquid level range, the working fluid inlet float valve is controlled to open, and after the liquid level reaches the preset liquid level range, the working fluid inlet float valve is controlled to close.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The vacuum pump unit and control method of the present invention solve the problems of complicated operation process, easy operation error, low automation level, etc. in the start and stop of the existing vacuum pump unit, realize the automatic operation of the vacuum pump unit, and improve production efficiency. In addition, the present invention can also ensure the safety of operation, and is particularly suitable for situations involving dangerous chemicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a vacuum pump unit of the present invention;

[0033] In the figure, 1-nitrogen purge device; 101-nitrogen pipeline, 102-nitrogen pressure reducing valve, 103-nitrogen pressure gauge, 104-nitrogen shut-off valve, 105-nitrogen check valve;

[0034] 2- vacuum main line and vacuum switching device; 202- vacuum main line, 203- vacuum cut-off valve, 204- vacuum pressure transmitter, 205- vacuum differential pressure transmitter, 206- vacuum filter, 207- three-way valve, 208- roots pump vacuum bypass;

[0035] 3- Roots vacuum pump device; 301- Roots pump inlet pipeline, 302- Roots vacuum pump, 303- first expansion joint, 304- Roots pump outlet pipeline, 305- circulating water outlet pipeline, 306- circulating water inlet pipeline;

[0036] 4-liquid ring vacuum pump device; 401-liquid ring pump inlet pipeline, 402-liquid ring vacuum pump, 403-expansion joint, 404-liquid ring vacuum pump outlet pipeline, 405-buffer tank, 406-buffer tank liquid level transmitter, 407-working fluid inlet float valve, 408-fresh working fluid inlet pipeline, 409-buffer tank outlet pipeline, 410-buffer tank overflow pipeline, 411-buffer tank drain pipeline, 412-buffer tank main drain pipe, 413-buffer tank working fluid outlet pipeline, 414-working fluid cooler, 415-working fluid flow transmitter, 416-working fluid cooler outlet pipeline, 417-working fluid pressure transmitter, 418-working fluid temperature transmitter, 419-refrigerant inlet pipeline, 420-refrigerant outlet pipeline;

[0037] 5- post-pump condensing device; 501- post-pump condenser, 502- condenser outlet pipeline, 503- condenser outlet temperature transmitter, 504- refrigerant inlet pipeline, 505- refrigerant outlet pipeline;

[0038] 6-vacuum return line and vacuum exhaust device; 601-vacuum outlet cut-off valve, 602-exhaust gas exhaust pipeline, 603-check valve, 604-vacuum return pipeline. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0040] like Figure 1 As shown, the present invention provides a vacuum pump unit, including: a nitrogen purge device 1, a vacuum main line and a vacuum switching device 2, a Roots vacuum pump device 3, and a liquid ring vacuum pump device 4. The control device is respectively connected to the nitrogen purge device 1, the vacuum main line and the vacuum switching device 2, the Roots vacuum pump 3, and the liquid ring vacuum pump device 4.

[0041] The control device includes a controller, a key module and a judgment module. Among them, the key module is equipped with six buttons, namely: start, stop, high vacuum start, high vacuum stop, emergency stop, and liquid level operation control, for operation by section personnel. On the one hand, the key module is configured to receive start, stop, high vacuum start, high vacuum stop, emergency stop, and liquid level operation control instructions and send them to the controller; on the other hand, it is configured to receive a stop instruction and send it to the judgment module. The judgment module is configured to determine whether the high vacuum is in an on or off state when "stop" in the key module is triggered, and send the high vacuum state to the controller. On the one hand, the controller receives the high vacuum state sent by the judgment module, and on the other hand, it is configured to respond to the instructions generated when the section personnel trigger the button of the key module.

[0042] The nitrogen purge device 1, the vacuum main line and the vacuum switching device 2, the Roots vacuum pump device 3, and the liquid ring vacuum pump device 4 are described in detail below. The nitrogen purge device 1 includes a nitrogen pipeline 101, on which a nitrogen pressure reducing valve 102, a nitrogen pressure gauge 103, a nitrogen shut-off valve 104, and a nitrogen check valve 105 are sequentially arranged; the nitrogen purge device 1 is connected to the vacuum main line and the vacuum switching device 2 through the nitrogen pipeline 101. The control device mentioned above is connected to the nitrogen purge device 1, specifically, the controller is connected to the nitrogen shut-off valve 104 to control the nitrogen to purge the Roots vacuum pump device 3 or the liquid ring vacuum pump device 4.

[0043] The vacuum main line and vacuum switching device 2 include a vacuum main line 202, on which a vacuum cut-off valve 203, a vacuum pressure transmitter 204, a vacuum filter 206, and a three-way valve 207 are sequentially arranged; a vacuum differential pressure transmitter 205 is arranged in parallel at the vacuum filter 206; the three-way valve 207 is provided with three interfaces, one of which is connected to the vacuum main line 202, and the other two interfaces are respectively connected to the roots pump vacuum bypass 208 and the roots vacuum pump device 3. The control device is connected to the three-way valve 207, and specifically, the controller is connected to the three-way valve 207 to control the three-way valve 207 to switch between the roots pump vacuum bypass 208 and the roots vacuum pump device 3, and finally realize that the vacuum main line 202 is selectively connected to the roots pump vacuum bypass 208 or the roots vacuum pump device 3. The aforementioned control device is connected to the vacuum main line and the vacuum switching device 2 . Specifically, the controller is connected to the vacuum cut-off valve 203 to control the vacuum gas to enter the Roots vacuum pump device 3 or the liquid ring vacuum pump device 4 .

[0044] The Roots vacuum pump device 3 includes a Roots vacuum pump 302, and the four interfaces of the Roots vacuum pump 302 are respectively connected to the Roots pump inlet pipeline 301, the first expansion joint 303, the circulating water outlet pipeline 305, and the circulating water inlet pipeline 306; the other end of the first expansion joint 303 is connected to the Roots pump outlet pipeline 304. The other two interfaces of the three-way valve 207 mentioned above are respectively connected to the Roots pump vacuum bypass 208 and the Roots vacuum pump device 3, which are specifically connected to the Roots pump inlet pipeline 301 in the Roots vacuum pump device 3, so that the vacuum main pipeline 202 can be connected to either the Roots pump vacuum bypass 208 or the Roots pump inlet pipeline 301. It should be particularly noted that one end of the Roots pump vacuum bypass 208 can be connected to the three-way valve 207, and the other end thereof is connected to the Roots pump outlet pipeline 304.

[0045] It is mentioned above that the control device is connected to the Roots vacuum pump 3, specifically, the controller is connected to the Roots vacuum pump 302 to control the start or shut down of the Roots vacuum pump 302. It is mentioned above that the controller is connected to the three-way valve 207 to control the three-way valve 207 to switch between the Roots pump vacuum bypass 208 and the Roots vacuum pump device 3, specifically, the controller is connected to the three-way valve 207 to control the three-way valve 207 to switch between the Roots pump vacuum bypass 208 and the Roots pump inlet pipeline 301.

[0046] The liquid ring vacuum pump device 4 includes a liquid ring pump inlet pipeline 401, on which a liquid ring vacuum pump 402, a second expansion joint 403, a liquid ring vacuum pump outlet pipeline 404, and a buffer tank 405 are sequentially arranged. A buffer tank outlet pipeline 409 is arranged on the top surface of the buffer tank 405. A buffer tank working fluid outlet pipeline 413 is arranged on the lower side of the buffer tank 405. The other end of the working fluid outlet pipeline 413 is connected to one end of a working fluid cooler 414. The other end of the working fluid cooler 414 is connected to the liquid ring vacuum pump 402 through a working fluid cooler outlet pipeline 416 to achieve cooling of the liquid ring vacuum pump 402. A refrigerant inlet pipeline 419 and a refrigerant outlet pipeline 420 are arranged on the side of the working fluid cooler 414 to achieve cooling of the working fluid. A working fluid flow transmitter 415, a working fluid pressure transmitter 417, and a working fluid temperature transmitter 418 are provided on the working fluid cooler outlet pipeline 416 to monitor the working fluid flow, pressure, and temperature. The aforementioned control device is connected to the liquid ring vacuum pump device 4, specifically, the controller is connected to the liquid ring vacuum pump 402 to control the start or shut down of the liquid ring vacuum pump 402.

[0047] The liquid ring pump inlet pipeline 401 is connected to the Roots pump outlet pipeline 304, so when the three-way valve 207 is switched to the Roots pump vacuum bypass 208, the vacuum air of the vacuum main pipeline 202 passes through the vacuum filter 206, the Roots pump outlet pipeline 304, and the liquid ring pump inlet pipeline 401 in sequence, and enters the liquid ring vacuum pump 402, and the nitrogen of the nitrogen purge device also enters the liquid ring vacuum pump 402 along the above path; when the three-way valve 207 is switched to the Roots pump inlet pipeline 301, the vacuum air of the vacuum main pipeline 202 passes through the vacuum filter 206 and the Roots pump inlet pipeline 301 in sequence, and enters the Roots vacuum pump 302.

[0048] In a preferred embodiment of the present invention, a buffer tank level transmitter 406 is provided on the side wall of the buffer tank 405 to collect the liquid level in the buffer tank 405 and send it to the control device. More preferably, a fresh working liquid inlet pipeline 408 is provided on the top surface of the buffer tank 405 to replenish fresh working liquid through the fresh working liquid inlet pipeline 408. A working liquid inlet float valve 407 is provided at one end of the fresh working liquid inlet pipeline 408 in the buffer tank 405. The control device is connected to the buffer tank level transmitter 406 and the working liquid inlet float valve 407. Specifically, the judgment modulus is connected to the buffer tank level transmitter 406, and the controller is connected to the working liquid inlet float valve 407 to control the flow rate of the fresh working liquid.

[0049] The buffer tank level transmitter 406 collects the liquid level in the buffer tank 405 and sends it to the judgment module. The judgment module determines whether the real-time liquid level is within the preset liquid level range and sends the judgment result to the controller. It should be noted that the buffer tank level transmitter 406 collects the liquid level and sends it to the judgment module uninterruptedly. When the real-time liquid level is lower than the low liquid level setting value in the preset liquid level range, the controller controls the working liquid inlet float valve 407 to open, replenishes the working liquid into the buffer tank 405, and the liquid level rises; when the preset liquid level range is reached, the controller controls the working liquid inlet float valve 407 to close. When the real-time liquid level is higher than the high liquid level setting value in the preset liquid level range, the working liquid is discharged from the system through the buffer tank overflow pipeline 410 and the buffer tank main drain pipe 412. Preferably, the buffer tank overflow pipeline 410 is provided with a U-shaped bend to prevent the gas in the buffer tank main drain pipe 412 from flowing back into the tank. More preferably, the bottom surface of the buffer tank 405 is provided with a buffer tank drain pipeline 411. The buffer tank overflow pipeline 410 and the buffer tank drain pipeline 411 are both connected to the buffer tank main drain pipe 412 .

[0050] It should be noted that the buffer tank overflow pipeline 410 is set at the high liquid level setting value in the preset liquid level range. If the liquid level in the buffer tank 405 is higher than the high liquid level setting value in the preset liquid level range, the working fluid will automatically enter the buffer tank overflow pipeline 410 and then be discharged from the system through the buffer tank main drain pipe 412.

[0051] In a preferred embodiment of the present invention, the vacuum pump unit further includes a post-pump condensation device 5, specifically a post-pump condenser 501. One end of the post-pump condenser 501 is connected to the buffer tank outlet pipeline 409, and the other end is connected to the condenser outlet pipeline 502. A refrigerant inlet pipeline 504 and a refrigerant outlet pipeline 505 are provided on the side of the post-pump condenser 501 to enable the post-pump condenser 501 to condense the material. Preferably, a condenser outlet temperature transmitter 503 is provided on the condenser outlet pipeline 502 to adjust the flow of the refrigerant inlet pipeline 504 according to the condenser outlet temperature.

[0052] In a more preferred embodiment of the present invention, the vacuum pump unit further includes a vacuum return line and a vacuum exhaust device 6, specifically including an exhaust gas discharge pipeline 602 and a vacuum return pipeline 604. The condenser outlet pipeline 502 is connected to the vacuum return pipeline 604 and the exhaust gas discharge pipeline 602 respectively. A vacuum outlet shut-off valve 601 is provided on the condenser outlet pipeline 502. A check valve 603 is provided on the exhaust gas discharge pipeline 602.

[0053] In addition, the present invention also provides a control method for a vacuum pump unit. It should be noted that before operating the vacuum pump unit, a preparation process must be completed first. The preparation process includes: ensuring that the circulating water outlet pipeline 305, the circulating water inlet pipeline 306, the fresh working fluid inlet pipeline 408, the refrigerant inlet pipeline 419, the refrigerant outlet pipeline 420, the buffer tank overflow pipeline 410, the buffer tank drain pipeline 411, the buffer tank main drain pipe 412, the refrigerant inlet pipeline 504, and the refrigerant outlet pipeline 505 are unobstructed.

[0054] Operation 1: One-key start

[0055] The section personnel triggers the "start" button of the key module in the control device, and the controller responds to the "start" instruction.

[0056] (1) Control the liquid ring vacuum pump 402 to start.

[0057] (2) After the liquid ring vacuum pump 402 has been running for 10 seconds, the vacuum shut-off valve 203 is controlled to open.

[0058] At this time, the vacuum gas in the vacuum main line 202 does not pass through the Roots vacuum pump 302, and enters the liquid ring vacuum pump 402 through the Roots pump vacuum bypass 208. Only the liquid ring vacuum pump 402 in the vacuum pump unit is in operation, which is a low vacuum condition. In addition, if the process involves highly dangerous chemicals such as ethylene oxide, only the liquid ring vacuum pump 402 is running in the low vacuum mode of this embodiment, and ethylene oxide can be vacuum operated without passing through the Roots vacuum pump 302, which essentially ensures safe operation. The vacuum operation range of this mode is 15kPaA~1kPaA.

[0059] It should be noted that when the vacuum pump unit stops running, the three-way valve 207 is connected to the vacuum bypass 208 of the Roots pump.

[0060] Operation 2: One-button high vacuum start

[0061] The section personnel triggers the "high vacuum start" button of the key module in the control device, and the controller responds to the "high vacuum start" instruction.

[0062] (1) Control the three-way valve 207 to switch from the Roots pump vacuum bypass 208 to the Roots pump inlet pipeline 301.

[0063] (2) After 5 seconds, the Roots vacuum pump 302 is controlled to start.

[0064] At this time, the vacuum gas in the vacuum main line 202 enters and passes through the Roots vacuum pump 302. The Roots vacuum pump 302 and the liquid ring vacuum pump 402 in the vacuum pump unit are both in operation, which is a high vacuum condition. The vacuum operation range of this mode is 1 kPaA to 0.5 kPaA.

[0065] Operation three: One-button high vacuum stop

[0066] The section personnel triggers the "high vacuum stop" button of the key module in the control device, and the controller responds to the "high vacuum stop" instruction.

[0067] (1) Control the vacuum cut-off valve 203 to close.

[0068] (2) After 5 seconds, the Roots vacuum pump 302 is controlled to be closed and the nitrogen shut-off valve 104 is controlled to be opened to purge the Roots vacuum pump 302 .

[0069] (3) After the purge time reaches the purge time threshold (which can be set to 3-5 minutes), the nitrogen shut-off valve 104 is controlled to close, and at the same time, the three-way valve 207 is controlled to switch from the Roots pump inlet pipeline 301 to the Roots pump vacuum bypass 208.

[0070] (4) Control the vacuum shut-off valve 203 to open after 5 seconds. It should be noted that the 5 seconds here start from the completion of "controlling the nitrogen shut-off valve 104 to close and controlling the three-way valve 207 to switch from the Roots pump inlet pipeline 301 to the Roots pump vacuum bypass 208", not when the "high vacuum stop" command is received.

[0071] The working conditions at this time are the same as those in operation 1 and will not be described in detail here.

[0072] Operation 4: One-key shutdown

[0073] The section personnel trigger the "stop" button of the key module in the control device, and the judgment module first judges whether the high vacuum state is on or off, and then sends it to the controller in response to the "stop" command.

[0074] If the high vacuum is on at this time,

[0075] (1) Control the vacuum cut-off valve 203 to close.

[0076] (2) After 5 seconds, the Roots vacuum pump 302 is controlled to be closed and the nitrogen shut-off valve 104 is controlled to be opened to purge the Roots vacuum pump 302 .

[0077] (3) After the purge time reaches the purge time threshold (which can be set to 3-5 minutes), the three-way valve 207 is controlled to switch from the Roots pump inlet pipeline 301 to the Roots pump vacuum bypass 208.

[0078] (4) The three-way valve 207 starts timing after switching from the Roots pump inlet pipeline 301 to the Roots pump vacuum bypass 208. After the liquid ring vacuum pump 402 reaches the operating time threshold (which can be set to 3-5 minutes), the nitrogen shut-off valve 104 is controlled to close, and the liquid ring vacuum pump 402 is controlled to close at the same time.

[0079] At this time, both the Roots vacuum pump 302 and the liquid ring vacuum pump 402 are in a shutdown state and only receive the "start" command control.

[0080] If the high vacuum is off at this time,

[0081] (1) Control the vacuum cut-off valve 203 to close.

[0082] (2) After 5 seconds, the nitrogen shut-off valve 104 is controlled to open (at this time, the liquid ring vacuum pump 402 continues to run).

[0083] (3) After the liquid ring vacuum pump 402 reaches the operating time threshold (which can be set to 3-5 minutes), the nitrogen shut-off valve 104 is controlled to close, and the liquid ring vacuum pump 402 is controlled to close at the same time.

[0084] At this time, both the Roots vacuum pump 302 and the liquid ring vacuum pump 402 are in a shutdown state and only receive the "start" command control.

[0085] Operation 5: Emergency shutdown

[0086] The section personnel triggers the "emergency stop" button of the key module in the control device, and the controller responds to the "emergency stop" instruction.

[0087] The vacuum cut-off valve 203 is controlled to be closed, the three-way valve 207 is controlled to switch from the Roots pump inlet pipeline 301 to the Roots pump vacuum bypass 208, and the Roots vacuum pump 302 and the liquid ring vacuum pump 402 are controlled to be closed. It should be noted that the above operations are performed simultaneously.

[0088] At this time, both the Roots vacuum pump 302 and the liquid ring vacuum pump 402 are in a shutdown state and only receive the "start" command control.

[0089] Operation 6: Liquid level operation control

[0090] The section personnel triggers the "liquid level operation control" button of the key module in the control device, and the buffer tank level transmitter 406 collects the liquid level in the buffer tank 405 in real time and sends it to the judgment module; the judgment module first judges whether the liquid level in the buffer tank 405 is lower than the preset liquid level range, and then sends it to the controller in response to the "liquid level operation control" instruction.

[0091] If the real-time liquid level is lower than the low liquid level setting value in the preset liquid level range,

[0092] (1) Control the working fluid inlet float valve 407 to open, replenish working fluid into the buffer tank 405, and raise the liquid level;

[0093] (2) When the liquid level reaches the preset liquid level range, the working liquid inlet float valve 407 is controlled to close.

[0094] Example 1

[0095] In the production of a certain raw material medicine, a vacuum degree of 300Pa is required, and the vacuum pump unit of the present invention is used for vacuum operation. The following data are obtained by using the vacuum pump unit control method of the present invention:

[0096] Operation time: intermittent

[0097] Work section personnel setting: 1 operator.

[0098] During the operation, the start and stop operations are simple, the automation level is high, and the production efficiency is high even if only one person is deployed. It solves the problems of cumbersome operation process, easy operation errors, and low automation level in the prior art, realizes the automatic operation of the vacuum pump unit, and improves production efficiency.

[0099] Example 2

[0100] In the production of a certain raw material medicine, a vacuum degree of 100Pa is required, and the vacuum pump unit of the present invention is used for vacuum operation. The following data are obtained by using the vacuum pump unit control method of the present invention:

[0101] Operation time: intermittent

[0102] Work section personnel setting: 1 operator.

[0103] During operation, the start and stop operations are simple, the automation level is high, and it is not easy to make mistakes.

[0104] Comparative Example 1

[0105] In the production of a certain raw material medicine, a vacuum degree of 300Pa is required, and the vacuum pump unit of the present invention is used for vacuum operation. However, the six buttons configured in the key module are not used, and all operations are performed manually, and the following data are obtained:

[0106] Operation time: intermittent

[0107] Work section personnel setup: 2 operators.

[0108] During the operation, it is necessary to manually start and stop the high vacuum mode of the Roots vacuum pump 302 and the liquid ring vacuum pump in sequence, which is cumbersome and prone to errors.

[0109] Comparative Example 2

[0110] In the production of a certain raw material medicine, a vacuum degree of 100Pa is required, and the vacuum pump unit of the present invention is used for vacuum operation. However, the six buttons configured in the key module are not used, and all operations are performed manually, and the following data are obtained:

[0111] Operation time: intermittent

[0112] Work section personnel setup: 2 operators.

[0113] During the operation, it is necessary to manually open or close the valves in sequence and stop the liquid ring vacuum pump 402 to complete the shutdown of the entire unit, which is a cumbersome operation.

[0114] In addition, if the process involves highly dangerous chemicals such as ethylene oxide, it is necessary to strictly prevent ethylene oxide from entering the Roots vacuum pump 302 and strictly prevent ethylene oxide from accumulating in the pipeline and equipment. Since multiple valves need to be operated during the start and stop process, once a person makes an operational error, very serious consequences will result. The one-button start and stop operation of the present invention can reduce operational errors. Therefore, the operational safety of Example 1 and Example 2 is higher than that of Comparative Example 1 and Comparative Example 2.

[0115] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0116] In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0117] The above technical solution is only one implementation mode of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. A vacuum pump unit, Features: The invention comprises a control device and a nitrogen purge device, a vacuum main line and a vacuum switching device, a Roots vacuum pump device and a liquid ring vacuum pump device which are connected in sequence; one end of the vacuum main line and the vacuum switching device close to the Roots vacuum pump device is also provided with a three-way valve and a Roots pump vacuum bypass, the Roots pump vacuum bypass is connected to the liquid ring vacuum pump device, and the vacuum main line is selectively connected to the Roots pump vacuum bypass or the Roots vacuum pump device; the control device is respectively connected to the nitrogen purge device, the vacuum main line and the vacuum switching device, the Roots vacuum pump, the liquid ring vacuum pump device and the three-way valve.

2. The vacuum pump unit according to claim 1, Features: The control device comprises The key module is configured to receive start, stop, high vacuum start, high vacuum stop, emergency stop, and liquid level operation control instructions and send them to the controller; on the other hand, it is configured to receive a stop instruction and send it to the judgment module; A judgment module, which is configured to receive a shutdown command sent by the key module, judge a high vacuum state, and send the high vacuum state to a controller; The controller is configured to receive the high vacuum state sent by the judgment module on the one hand, and to control the nitrogen purge device, the vacuum main line and the vacuum switching device, the Roots vacuum pump, the liquid ring vacuum pump device, and the three-way valve in response to the instructions sent by the key module on the other hand.

3. The vacuum pump unit according to claim 1, Features: The liquid ring vacuum pump device is provided with a buffer tank, and a buffer tank liquid level transmitter is provided on the side wall of the buffer tank; The buffer tank is provided with a fresh working fluid inlet pipeline, and one end of the fresh working fluid inlet pipeline arranged in the buffer tank is provided with a working fluid inlet float valve; The control device is connected to the buffer tank liquid level transmitter and the working fluid inlet float valve.

4. The vacuum pump unit according to claim 3, Features: A buffer tank overflow pipeline is provided on the side wall of the buffer tank.

5. The vacuum pump unit according to claim 4, Features: The overflow pipeline of the buffer tank is provided with a U-shaped bend.

6. The vacuum pump unit according to claim 1, Features: The vacuum pump unit also includes a post-pump condensation device connected to the liquid ring vacuum pump device.

7. The vacuum pump unit according to claim 6, Features: The post-pump condensation device is provided with a condenser outlet pipeline, on which a condenser outlet temperature transmitter is provided.

8. The vacuum pump unit according to claim 6, Features: The vacuum pump unit also includes a vacuum return line and a vacuum exhaust device, which are connected to the post-pump condensing device.

9. A control method for a vacuum pump unit, Features: include If a start command is received, the following operations are performed: the liquid ring vacuum pump is controlled to start; after the liquid ring vacuum pump runs for 10 seconds, the vacuum cut-off valve is controlled to open; If a high vacuum start command is received, the following operations are performed: the three-way valve is controlled to switch from the Roots pump vacuum bypass to the Roots pump inlet pipeline; the Roots vacuum pump is controlled to start after 5 seconds; If a high vacuum stop command is received, the following operations are performed: the vacuum shut-off valve is controlled to close; after 5 seconds, the Roots vacuum pump is controlled to close and the nitrogen shut-off valve is controlled to open to purge the Roots vacuum pump; after the purge time reaches the purge time threshold, the nitrogen shut-off valve is controlled to close and the three-way valve is controlled to switch from the Roots pump inlet pipeline to the Roots pump vacuum bypass; after 5 seconds, the vacuum shut-off valve is controlled to open; If a shutdown command is received and the high vacuum open state sent by the judgment module is detected, the following operations are performed: the vacuum shut-off valve is controlled to be closed; after 5 seconds, the Roots vacuum pump is controlled to be closed and the nitrogen shut-off valve is controlled to be opened at the same time; after the purge time reaches the purge time threshold, the three-way valve is controlled to switch from the Roots pump inlet pipeline to the Roots pump vacuum bypass; after the liquid ring vacuum pump reaches the operating time threshold, the nitrogen shut-off valve is controlled to be closed and the liquid ring vacuum pump is controlled to be closed at the same time; If a shutdown command and a high vacuum shutdown state sent by the judgment module are received, the following operations are performed: the vacuum shut-off valve is controlled to be closed; the nitrogen shut-off valve is controlled to be opened after 5 seconds; after the liquid ring vacuum pump reaches the operating time threshold, the nitrogen shut-off valve is controlled to be closed, and the liquid ring vacuum pump is controlled to be closed at the same time; If an emergency stop command is received, the following operations are performed: control the vacuum cut-off valve to close, control the three-way valve to switch from the Roots pump inlet pipeline to the Roots pump vacuum bypass, and control the Roots vacuum pump and liquid ring vacuum pump to close.

10. The method according to claim 9, Features: The control method of the vacuum pump unit also includes If a liquid level operation control instruction is received, the following operations are performed: if the real-time liquid level is lower than the low liquid level setting value in the preset liquid level range, the working fluid inlet float valve is controlled to open, and after the liquid level reaches the preset liquid level range, the working fluid inlet float valve is controlled to close.

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