CN113982928B - Series-parallel connection combined system of screw vacuum pump and liquid ring vacuum pump - Google Patents
Series-parallel connection combined system of screw vacuum pump and liquid ring vacuum pump Download PDFInfo
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- CN113982928B CN113982928B CN202111274959.0A CN202111274959A CN113982928B CN 113982928 B CN113982928 B CN 113982928B CN 202111274959 A CN202111274959 A CN 202111274959A CN 113982928 B CN113982928 B CN 113982928B
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- 239000007788 liquid Substances 0.000 title claims abstract description 148
- 238000002156 mixing Methods 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 claims description 18
- 239000000498 cooling water Substances 0.000 claims description 15
- 239000000110 cooling liquid Substances 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 238000005086 pumping Methods 0.000 description 12
- 239000000203 mixture Substances 0.000 description 10
- 230000007797 corrosion Effects 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 5
- 238000000605 extraction Methods 0.000 description 5
- 230000000903 blocking effect Effects 0.000 description 3
- 239000011247 coating layer Substances 0.000 description 3
- 230000006835 compression Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 3
- 239000000428 dust Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000000750 progressive effect Effects 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 238000013021 overheating Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011345 viscous material Substances 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
- F04C23/005—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of dissimilar working principle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C19/00—Rotary-piston pumps with fluid ring or the like, specially adapted for elastic fluids
- F04C19/004—Details concerning the operating liquid, e.g. nature, separation, cooling, cleaning, control of the supply
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C25/00—Adaptations of pumps for special use of pumps for elastic fluids
- F04C25/02—Adaptations of pumps for special use of pumps for elastic fluids for producing high vacuum
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
- F04C28/02—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids specially adapted for several pumps connected in series or in parallel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
- F04C28/28—Safety arrangements; Monitoring
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
- F04C29/12—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Applications Or Details Of Rotary Compressors (AREA)
Abstract
The invention discloses a serial-parallel connection combined system of a screw vacuum pump and a liquid ring vacuum pump, which comprises a screw vacuum pump, a liquid ring pump air inlet check valve, a screw pump air inlet check valve, an air inlet two-position three-way pneumatic valve, a screw pump air inlet shutoff valve, a screw pump air outlet check valve, a tail gas mixing ejector, a gas-liquid separator, a circulating pump and a pressure transmitter; when the real-time pressure of the pressure transmitter is larger than a preset value, the air inlet two-position three-way pneumatic valve is switched to be communicated with the first air inlet and the air outlet of the air inlet two-position three-way pneumatic valve, the second air inlet and the air outlet of the air inlet two-way pneumatic valve are closed, and the liquid ring vacuum pump is connected with the screw vacuum pump in parallel at the moment; when the real-time pressure value of the pressure transmitter is smaller than or equal to a preset value, the air inlet two-position three-way pneumatic valve is switched to the second air inlet of the air inlet two-position three-way pneumatic valve to be communicated with the air outlet of the air inlet two-way pneumatic valve, the first air inlet of the air inlet two-way pneumatic valve is closed with the air outlet of the air inlet two-way pneumatic valve, at the moment, the liquid ring vacuum pump is connected with the screw vacuum pump in series, and the series-parallel connection combined system of the screw vacuum pump and the liquid ring vacuum pump can improve the running stability of a vacuum unit system.
Description
Technical Field
The invention relates to the technical field of vacuum pumps, in particular to a serial-parallel connection combined system of a screw vacuum pump and a liquid ring vacuum pump.
Background
Vacuum pumps refer to devices or apparatus that draw air from a container being evacuated using mechanical, physical, chemical, or physicochemical means to obtain a vacuum. The performances of the vacuum pumps with different structures are different, in industrial application, the requirements of different air extraction capacities and the requirements of working vacuum degrees are required to be met, and generally, a single vacuum pump is difficult to meet the requirements of users, so that a plurality of vacuum pumps are required to form a vacuum unit system to realize.
The traditional vacuum unit system adopts a plurality of Roots vacuum pumps to be provided with a backing pump, and the backing pump can be a liquid ring vacuum pump, an oil type rotary vane pump, a screw vacuum pump or a slide valve vacuum pump. But basically, a single type of backing pump is selected to form a vacuum unit system with the Roots vacuum pump. However, for different backing pumps, the medium pumped by the liquid ring pump can be a process medium containing dust, viscous substances, corrosive gas, inflammable and explosive substances and the like, and the pumping capacity is very wide and ranges from 20m 3/h-20000m3/h, but the vacuum degree and pumping capacity of the liquid ring pump are completely influenced by the temperature of circulating liquid, even at normal temperature, the vacuum degree of the liquid ring pump can only reach 3500Pa, and one or more Roots vacuum pumps are required to be arranged at the air inlet of the liquid ring pump in order to obtain higher vacuum degree. However, the Roots vacuum pump has a disadvantage that, for example, when the pumping capacity of the liquid ring pump is affected by the temperature of the circulating liquid, the vacuum degree at the inlet is lowered, and the operation pressure difference of the Roots vacuum pump is increased, so that the exhaust temperature of the Roots vacuum pump is increased and the current is increased. In the application environment with poor cooling water working condition, particularly at high temperature in summer, the circulation liquid temperature of the liquid ring pump is often too high, so that the Roots vacuum pump is overloaded and overheated, and the frequent tripping or overheating and blocking of the Roots vacuum pump of the vacuum unit are caused.
If the front stage adopts a screw vacuum pump, the screw pump can achieve higher vacuum degree, and the air extraction capacity and the ambient temperature and the cooling water temperature are not directly related. However, due to the structural characteristics, the air extraction capacity of the screw vacuum pump is generally between 100 and 2000m 3/h, so that for some vacuum systems needing larger air extraction capacity, a plurality of Roots vacuum pumps are also required to be equipped to realize gradual increase of the air extraction capacity, and the purpose of the screw vacuum pump is slightly different from that of a liquid ring pump provided with a plurality of Roots pumps to gradually increase the vacuum degree of the system. However, due to the smaller pumping capacity of the screw vacuum pump, the screw vacuum pump is suitable for the pumping capacity of the application, and the compression ratio between the Roots pumps is often too high, so that overheating is caused in the running process of the Roots vacuum pump. Meanwhile, the screw vacuum pump can directly exhaust the atmosphere, has larger compression density for gas, and can not reduce the compression heat of the gas through circulating liquid like a liquid ring pump. The temperature of the exhaust port of the screw vacuum pump is very high, so that carbonization and polymerization of hydrocarbon gas occur during the suction of part of the organic compounds, causing adhesion thereof to the screw rotor, and screw pump failure occurs.
The upper surface of the screw vacuum pump flow-through element is made of corrosion-resistant materials, but the corrosion problem still cannot be thoroughly solved, because the coating layer falls off from the raw materials under the high-temperature environment due to different expansion coefficients, if the coating layer is directly made of expensive corrosion-resistant materials, the coating layer is difficult to process, and the equipment cost is too high. At the same time, even if expensive corrosion-resistant materials are adopted, the corrosion of the bearing caused by the penetration of corrosive gas through the gear box of the screw vacuum pump to the gear can not be solved.
Therefore, a brand new combination is needed to solve the defects and hidden troubles existing in the existing single Roots vacuum pump-liquid ring vacuum pump or Roots vacuum pump-screw vacuum pump combination in the traditional vacuum unit system, so as to realize more reliable operation.
Disclosure of Invention
The invention aims to provide a serial-parallel combined system of a screw vacuum pump and a liquid ring vacuum pump so as to improve the running stability of a vacuum unit system.
The invention provides a series-parallel connection combined system of a screw vacuum pump and a liquid ring vacuum pump, which comprises a screw vacuum pump, a liquid ring pump air inlet one-way valve, a screw pump air inlet one-way valve, an air inlet two-position three-way pneumatic valve, a screw pump air inlet shutoff valve, a screw pump air outlet one-way valve, a tail gas mixing injector, a gas-liquid separator, a circulating pump and a pressure transmitter;
The air inlet end of the air inlet shutoff valve of the screw pump is communicated with the process air inlet through a first pipeline, the air outlet end of the air inlet shutoff valve of the screw pump is communicated with the air inlet of the screw vacuum pump through a second pipeline, the air outlet end of the screw vacuum pump is communicated with the inlet end of the tail gas mixing injector through a third pipeline, the second pipeline is provided with an air inlet check valve of the screw pump, and the third pipeline is provided with an air outlet check valve of the screw pump;
The inlet end of the liquid ring vacuum pump is communicated with the process gas inlet through a fourth pipeline, an inlet end to an outlet end of the fourth pipeline are sequentially provided with an inlet two-position three-way pneumatic valve and a liquid ring pump inlet check valve, the outlet end of the liquid ring vacuum pump is communicated with the inlet end of the tail gas mixing ejector through a fifth pipeline, the first inlet end of the inlet two-position three-way pneumatic valve is connected with the process gas inlet, the second inlet end of the inlet two-position three-way pneumatic valve is communicated with a third pipeline, and the connection point of the inlet two-position three-way pneumatic valve and the third pipeline is positioned between the outlet end of the screw vacuum pump and the screw pump exhaust check valve;
the gas-liquid inlet end of the gas-liquid separator is communicated with the gas-liquid outlet end of the tail gas mixing ejector, the cooling liquid outlet end of the gas-liquid separator, the cooling liquid inlet end of the screw vacuum pump, the cooling liquid outlet end of the screw vacuum pump and the liquid inlet end of the liquid ring vacuum pump are communicated through a cooling pipeline, and a circulating pump is arranged on the cooling pipeline;
the first pipeline is communicated with the fourth pipeline, and the pressure transmitter is arranged on the fourth pipeline;
When the real-time pressure of the pressure transmitter is larger than a preset value, the air inlet two-position three-way pneumatic valve is switched to be communicated with the first air inlet and the air outlet of the air inlet two-position three-way pneumatic valve, the second air inlet and the air outlet of the air inlet two-way pneumatic valve are closed, and at the moment, the liquid ring vacuum pump is connected with the screw vacuum pump in parallel; when the real-time pressure value of the pressure transmitter is smaller than or equal to a preset value, the air inlet two-position three-way pneumatic valve is switched to be communicated with the second air inlet and the air outlet of the air inlet two-position three-way pneumatic valve, the first air inlet and the air outlet of the air inlet two-way pneumatic valve are closed, and the liquid ring vacuum pump and the screw vacuum pump are connected in series at the moment.
Based on the above, when the real-time pressure of the pressure transmitter is greater than the preset value, the liquid ring vacuum pump and the screw vacuum pump simultaneously perform parallel suction on the process main pipe, so as to achieve the maximum suction capacity, the second air inlet of the air inlet two-position three-way pneumatic valve is closed, the back pressure in the third pipeline is higher than the spring reverse force of the screw pump exhaust check valve, so that the screw pump exhaust check valve is jacked up, and the exhaust of the screw vacuum pump passes through the screw pump exhaust check valve. Meanwhile, the gas-liquid mixture of the liquid ring vacuum pump directly enters the tail gas mixing ejector, the pressure of the gas-liquid mixture discharged from the outlet end of the liquid ring vacuum pump is higher, the gas-liquid mixture enters the tail gas mixing ejector and finally is discharged into the gas-liquid separator, and the working principle of the tail gas mixing ejector is that the power is converted into the pressure through the Venturi effect, so that the power of the gas-liquid mixture discharged from the liquid ring vacuum pump is weakened after passing through the tail gas mixing ejector, and the gas-liquid mixture enters the gas-liquid separator and can be more effectively subjected to steam-water separation.
And the inlet end of the tail gas mixing ejector is directly connected to the exhaust port of the screw vacuum pump, so that the exhaust pressure of the screw vacuum pump can be reduced, the pressure difference between the air inlet end and the exhaust end of the screw vacuum pump is reduced, and the temperature of the exhaust end of the screw vacuum pump is further reduced.
Because the suction inlet of the tail gas mixing ejector has negative pressure, the liquid of the screw vacuum pump can be effectively brought out, namely, the airflow vortex formed at the exhaust port of the screw vacuum pump is completely solved, meanwhile, the amount of dust particles which are not easy to exhaust in the screw vacuum pump can be greatly reduced, more importantly, the exhaust pressure of the screw vacuum pump is slightly negative, the possibility of process gas entering can be thoroughly eliminated by adopting the positive pressure gear box of the nitrogen-protected screw vacuum pump, the screw vacuum pump is further effectively protected, and the screw vacuum pump is prevented from being corroded.
Along with the continuation of vacuumizing, when the real-time pressure value of the pressure transmitter is smaller than or equal to a set value, the air extracting capability of the liquid ring vacuum pump is greatly reduced along with the system approaching the limit vacuum which can be achieved, cavitation phenomenon can occur, and obvious vibration and noise phenomena can be caused. Meanwhile, as the vacuum degree is continuously improved, the liquid ring vacuum pump is most likely to have no pumping capacity, but plays a role in blocking, and part of gas and circulating liquid steam in the liquid ring vacuum pump are pumped into the screw vacuum pump, so that serious accident potential is caused.
At the moment, the gear of the air inlet two-position three-way pneumatic valve is changed, the first air inlet end of the air inlet two-position three-way pneumatic valve is closed, the second air inlet end is opened, namely, the air discharged by the screw vacuum pump directly enters the liquid ring vacuum pump, and at the moment, the liquid ring vacuum pump and the screw vacuum pump form a series mode.
In a higher vacuum environment, the front Roots pump starts to exert the supercharging function, and the advantage of parallel operation of the front pumps (the liquid ring vacuum pump and the screw vacuum pump) is not the same, but the screw vacuum pump independently realizes higher vacuum degree at the moment, so that the pressure of the exhaust port of the front Roots vacuum pump is ensured to be reduced, and the pressure difference of the Roots vacuum pump is reduced.
After the two-position three-way pneumatic valve of admitting air is switched, the gas exhausted by the screw vacuum pump mainly flows to the inlet end of the liquid ring vacuum pump, because the pressure of the exhaust end of the screw vacuum pump is greatly reduced, a large negative pressure is formed, at the moment, the exhaust check valve of the screw pump is automatically closed, and the gas is not led to enter the subsequent tail gas mixing injector, so that the original gas flow channel is automatically closed.
The exhaust air flow of the screw vacuum pump enters the liquid ring vacuum pump and is also discharged after being washed. Therefore, whenever the discharge pressure of the screw vacuum pump is not required to be higher than one atmosphere, the gear box at the discharge end of the screw vacuum pump is more favorably protected, so that the screw vacuum pump is more favorably used for sucking corrosive and viscous process media.
In the above technical solution, the present invention may be further improved as follows.
Preferably, the vapor-liquid separator is internally provided with a heat exchanger.
Preferably, the vapor-liquid separator is provided with a cooling water inlet and a cooling water outlet, wherein the cooling water inlet is communicated with the liquid inlet end of the heat exchanger, and the cooling water outlet is communicated with the liquid discharge end of the heat exchanger.
Preferably, the vapor-liquid separator is provided with a temperature transmitter.
Preferably, the vapor-liquid separator is provided with a liquid level transmitter.
Preferably, the exhaust gas mixing injector is a water injector.
Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.
FIG. 1 is a schematic diagram of a serial-parallel combination system of a screw vacuum pump and a liquid ring vacuum pump according to an embodiment of the present invention;
In the drawings of which there are shown,
The device comprises a screw vacuum pump 10, a liquid ring vacuum pump 11, a liquid ring pump air inlet check valve 12, a screw pump air inlet check valve 13, an air inlet two-position three-way pneumatic valve 14, a screw pump air inlet shutoff valve 15, a screw pump air outlet check valve 16, a tail gas mixing injector 17, a gas-liquid separator 18, a circulating pump 19, a pressure transmitter 20, a temperature transmitter 21 and a liquid level transmitter 22;
A first line 31, a second line 32, a third line 33, a fourth line 34, a fifth line 35, a cooling line 36.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
Referring to fig. 1, the present embodiment provides a serial-parallel combination system of a screw and a liquid ring vacuum pump 11, which includes a screw vacuum pump 10, a liquid ring vacuum pump 11, a liquid ring pump air intake check valve 12, a screw pump air intake check valve 13, an air intake two-position three-way pneumatic valve 14, a screw pump air intake shutoff valve 15, a screw pump air exhaust check valve 16, a tail gas mixing injector 17, a vapor-liquid separator 18, a circulating pump 19 and a pressure transmitter 20.
The air inlet end of the screw pump air inlet shutoff valve 15 is communicated with the process gas inlet through a first pipeline 31, the air outlet end of the screw pump air inlet shutoff valve 15 is communicated with the air inlet of the screw vacuum pump 10 through a second pipeline 32, the air outlet end of the screw vacuum pump 10 is communicated with the inlet end of the tail gas mixing injector 17 through a third pipeline 33, the second pipeline 32 is provided with a screw pump air inlet check valve 13, and the third pipeline 33 is provided with a screw pump air outlet check valve 16;
The inlet end of the liquid ring vacuum pump 11 is communicated with a process gas inlet through a fourth pipeline 34, an inlet end to an outlet end of the fourth pipeline 34 are sequentially provided with an inlet two-position three-way pneumatic valve 14 and a liquid ring pump inlet check valve 12, the outlet end of the liquid ring vacuum pump 11 is communicated with the inlet end of the tail gas mixing ejector 17 through a fifth pipeline 35, a first inlet end of the inlet two-position three-way pneumatic valve 14 is connected with the process gas inlet, a second inlet end of the inlet two-position three-way pneumatic valve 14 is communicated with a third pipeline 33, and a connection point of the inlet two-position three-way pneumatic valve 14 and the third pipeline 33 is positioned between the outlet end of the screw vacuum pump 10 and the screw pump exhaust check valve;
The gas-liquid inlet end of the gas-liquid separator 18 is communicated with the gas-liquid outlet end of the tail gas mixing injector, the cooling liquid outlet end of the gas-liquid separator 18, the cooling liquid inlet end of the screw vacuum pump 10, the cooling liquid outlet end of the screw vacuum pump 10 and the liquid inlet end of the liquid ring vacuum pump 11 are communicated through a cooling pipeline 36, and a circulating pump 19 is arranged on the cooling pipeline 36;
The first pipeline is communicated with the fourth pipeline 34, and the pressure transmitter 20 is arranged on the fourth pipeline 34;
When the real-time pressure of the pressure transmitter 20 is greater than a preset value, the air inlet two-position three-way pneumatic valve 14 is switched to be communicated with the first air inlet and the air outlet thereof, and the second air inlet and the air outlet thereof are closed, at the moment, the liquid ring vacuum pump 11 is connected with the screw vacuum pump 10 in parallel; when the real-time pressure value of the pressure transmitter 20 is smaller than or equal to the preset value, the air inlet two-position three-way pneumatic valve 14 is switched to be communicated with the second air inlet and the air outlet, the first air inlet and the air outlet are closed, and the liquid ring vacuum pump 11 and the screw vacuum pump 10 are connected in series.
Based on the above, when the real-time pressure of the pressure transmitter 20 is greater than the preset value, it is indicated that the pumping capability of the liquid ring vacuum pump 11 is still within the optimal efficiency range, the liquid ring vacuum pump 11 and the screw vacuum pump 10 simultaneously perform parallel suction on the process main pipe, so as to achieve the maximum pumping capability, the second air inlet of the air inlet two-position three-way pneumatic valve 17 is closed, and therefore, the back pressure in the third pipeline 33 is higher than the spring reverse force of the screw pump air discharge check valve 16, so that the screw pump air discharge check valve 16 is propped open, and the air discharge of the screw vacuum pump 10 passes through the screw pump air discharge check valve 16. The gas-liquid mixture of the liquid ring vacuum pump 11 which runs simultaneously directly enters the tail gas mixing ejector 17, the pressure of the gas-liquid mixture discharged from the outlet end of the liquid ring vacuum pump 11 is higher, the gas-liquid mixture enters the tail gas mixing ejector 17 and finally is discharged into the gas-liquid separator 18, and the working principle of the tail gas mixing ejector 17 is that the power is converted into the pressure through the Venturi effect, so that the power of the gas-liquid mixture discharged from the liquid ring vacuum pump 11 is weakened after passing through the tail gas mixing ejector 17, and the gas-liquid mixture enters the gas-liquid separator 18 and can be more effectively subjected to gas-water separation.
The inlet end of the tail gas mixing injector 17 is directly connected to the exhaust port of the screw vacuum pump 10, so as to reduce the exhaust pressure of the screw vacuum pump 10, thereby reducing the pressure difference between the air inlet end and the exhaust end of the screw vacuum pump 10, and further reducing the temperature of the exhaust end of the screw vacuum pump 10.
Because the suction inlet of the tail gas mixing ejector 17 has negative pressure (the negative pressure is generated by liquid discharge and ejection of the liquid ring vacuum pump 11), the liquid of the screw vacuum pump 10 can be effectively brought out, namely, the airflow vortex formed at the exhaust port of the screw vacuum pump 10 is completely solved, meanwhile, the amount of dust particles which are not easy to discharge in the screw vacuum pump 10 can be greatly reduced, more importantly, the exhaust pressure of the screw vacuum pump 10 is slightly negative, and the possibility of process gas entering can be thoroughly eliminated by adopting the positive pressure gearbox of the nitrogen-protected screw vacuum pump 10 at the moment, so that the screw vacuum pump 10 is effectively protected, and the screw vacuum pump 10 is prevented from being corroded.
Along with the vacuum pumping, when the real-time pressure value of the pressure transmitter 20 is smaller than or equal to the set value, the pumping capacity of the liquid ring vacuum pump 11 is greatly reduced along with the system approaching the limit vacuum which can be achieved, cavitation can occur, and obvious vibration and noise phenomena can be caused. Meanwhile, as the vacuum degree is continuously improved, the liquid ring vacuum pump 10 is most likely to have no pumping capacity, but plays a role in blocking, and part of gas and circulating liquid steam in the liquid ring vacuum pump 10 are pumped into the screw vacuum pump 10, so that serious accident potential is caused.
At this time, the gear of the air-intake two-position three-way pneumatic valve 14 is changed, the first air-intake end of the air-intake two-position three-way pneumatic valve 14 is closed, and the second air-intake end is opened, that is, the air discharged from the screw vacuum pump 10 directly enters the liquid ring vacuum pump 11, and at this time, the liquid ring vacuum pump 11 and the screw vacuum pump 10 form a series mode.
In a higher vacuum environment, the front Roots pump starts to exert the pressurizing function, and the advantage of parallel operation of the front pump (the liquid ring vacuum pump 11+the screw vacuum pump 10) is not the same, but the screw vacuum pump 10 alone realizes higher vacuum degree at the moment, so that the pressure of the exhaust port of the front Roots vacuum pump is ensured to be reduced, and the pressure difference of the Roots vacuum pump is reduced.
After the air inlet two-position three-way pneumatic valve 14 is switched, the air exhausted by the screw vacuum pump 10 mainly flows to the inlet end of the liquid ring vacuum pump 11, and the pressure of the exhaust end of the screw vacuum pump 11 is greatly reduced to form a large negative pressure, at the moment, the screw pump exhaust check valve 16 is automatically closed, and the air is not fed into the subsequent tail gas mixing injector 17, so that the original air flow channel is automatically closed.
The exhaust air flow from the screw vacuum pump 10 enters the liquid ring vacuum pump 11, and is likewise washed and then discharged. It is therefore advantageous to protect the gearbox at the discharge end of the progressive cavity vacuum pump 10 whenever the discharge pressure of the progressive cavity vacuum pump 10 is not required to be higher than one atmosphere, thereby making the progressive cavity vacuum pump 10 more advantageous for pumping corrosive, viscous process media.
At the same time, the total pressure difference of the screw vacuum pump 10 is reduced, the inlet pressure of the screw vacuum pump 10 is further reduced, and the screw vacuum pump is more effective for the use of a front-mounted Roots vacuum pump.
In the present application, it is to be explained that: the real-time pressure value of the pressure transmitter 20 is obtained by interlocking the temperatures of the circulating cooling water.
In the application, the heat exchanger is arranged in the vapor-liquid separator 18, the vapor-liquid separator 18 is provided with a cooling water inlet and a cooling water outlet, the cooling water inlet is communicated with the liquid inlet end of the heat exchanger, the cooling water outlet is communicated with the liquid outlet end of the heat exchanger, and the heat exchanger is arranged to provide the separation effect of the vapor-liquid separator 18.
In the present application, the vapor-liquid separator 18 is provided with the temperature transmitter 21 and the liquid level transmitter 22, and the temperature of the vapor-liquid separator 18 can be observed in real time by the temperature transmitter 21, and the liquid level in the vapor-liquid separator 18 can be observed in real time by the liquid level transmitter 22.
In the present embodiment, the exhaust gas mixing injector 17 is a water injector.
In summary, in the screw vacuum pump and liquid ring vacuum pump series-parallel connection combined system provided in this embodiment, the series-parallel connection state of the screw vacuum pump and the liquid ring vacuum pump can be adjusted according to the real-time pressure of the pressure transmitter, so that the best operation state is finally achieved, and the stability and the service life of the operation of the vacuum unit system are improved.
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered by the scope of the claims of the present invention. The technology, shape, and construction parts of the present invention, which are not described in detail, are known in the art.
Claims (4)
1. The serial-parallel connection combined system of the screw vacuum pump and the liquid ring vacuum pump is characterized by comprising a screw vacuum pump (10), a liquid ring vacuum pump (11), a liquid ring pump air inlet one-way valve (12), a screw pump air inlet one-way valve (13), an air inlet two-position three-way pneumatic valve (14), a screw pump air inlet shutoff valve (15), a screw pump air outlet one-way valve (16), a tail gas mixing injector (17), a vapor-liquid separator (18), a circulating pump (19) and a pressure transmitter (20);
the air inlet end of the screw pump air inlet shutoff valve (15) is communicated with the process air inlet through a first pipeline (31), the air outlet end of the screw pump air inlet shutoff valve (15) is communicated with the air inlet of the screw vacuum pump (10) through a second pipeline (32), the air outlet end of the screw vacuum pump (10) is communicated with the inlet end of the tail gas mixing injector (17) through a third pipeline (33), a screw pump air inlet check valve (13) is arranged on the second pipeline (32), and a screw pump air outlet check valve (16) is arranged on the third pipeline (33);
The inlet end of the liquid ring vacuum pump (11) is communicated with a process gas inlet through a fourth pipeline (34), an inlet end to an outlet end of the fourth pipeline (34) are sequentially provided with an inlet two-position three-way pneumatic valve (14) and a liquid ring pump inlet one-way valve (12), the outlet end of the liquid ring vacuum pump (11) is communicated with the inlet end of the tail gas mixing ejector (17) through a fifth pipeline (35), a first inlet end of the inlet two-position three-way pneumatic valve (14) is connected with the process gas inlet, a second inlet end of the inlet two-position three-way pneumatic valve (14) is communicated with a third pipeline (33), and a connecting point of the inlet two-position three-way pneumatic valve (14) and the third pipeline (33) is positioned between the outlet end of the screw vacuum pump (10) and the screw pump exhaust one-way valve (16);
The gas-liquid inlet end of the gas-liquid separator (18) is communicated with the gas-liquid outlet end of the tail gas mixing ejector (17), the cooling liquid outlet end of the gas-liquid separator (18), the cooling liquid inlet end of the screw vacuum pump (10), the cooling liquid outlet end of the screw vacuum pump (10) and the liquid inlet end of the liquid ring vacuum pump (11) are communicated through a cooling pipeline (36), a circulating pump (19) is arranged on the cooling pipeline (36), a heat exchanger is arranged in the gas-liquid separator (18), the gas-liquid separator (18) is provided with a cooling water inlet and a cooling water outlet, the cooling water inlet is communicated with the liquid inlet end of the heat exchanger, and the cooling water outlet is communicated with the liquid discharge end of the heat exchanger;
The first pipeline (31) is communicated with the fourth pipeline (34), and the pressure transmitter (20) is arranged on the fourth pipeline (34);
When the real-time pressure of the pressure transmitter (20) is larger than a preset value, the air inlet two-position three-way pneumatic valve (14) is switched to be communicated with the air inlet and the air outlet of the air inlet two-position three-way pneumatic valve, the second air inlet and the air outlet of the air inlet two-way pneumatic valve are closed, and at the moment, the liquid ring vacuum pump (11) is connected with the screw vacuum pump (10) in parallel; when the real-time pressure value of the pressure transmitter (20) is smaller than or equal to a preset value, the air inlet two-position three-way pneumatic valve (14) is switched to be communicated with the air outlet of the air inlet two-position three-way pneumatic valve, the first air inlet of the air inlet two-way pneumatic valve is closed with the air outlet of the air inlet two-way pneumatic valve, and the liquid ring vacuum pump (11) is connected with the screw vacuum pump (10) in series.
2. The screw vacuum pump and liquid ring vacuum pump series-parallel connection combined system according to claim 1, wherein the vapor-liquid separator (18) is provided with a temperature transmitter (21).
3. The screw vacuum pump and liquid ring vacuum pump series-parallel combination system according to claim 1, wherein the vapor-liquid separator (18) is provided with a liquid level transmitter (22).
4. A combined series-parallel system of a screw vacuum pump and a liquid ring vacuum pump according to claim 1, characterized in that the tail gas mixing ejector (17) is a water ejector.
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| CN202111274959.0A CN113982928B (en) | 2021-10-29 | 2021-10-29 | Series-parallel connection combined system of screw vacuum pump and liquid ring vacuum pump |
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| CN113982928A (en) | 2022-01-28 |
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