CN111578566A - Control system for gas bearing type centrifugal compressor - Google Patents
Control system for gas bearing type centrifugal compressor Download PDFInfo
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- CN111578566A CN111578566A CN202010429757.8A CN202010429757A CN111578566A CN 111578566 A CN111578566 A CN 111578566A CN 202010429757 A CN202010429757 A CN 202010429757A CN 111578566 A CN111578566 A CN 111578566A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/022—Compressor control arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B37/00—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00
- F04B37/10—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use
- F04B37/12—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use to obtain high pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
- F04B39/02—Lubrication
- F04B39/0207—Lubrication with lubrication control systems
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B51/00—Testing machines, pumps, or pumping installations
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B31/00—Compressor arrangements
- F25B31/002—Lubrication
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2600/00—Control issues
- F25B2600/02—Compressor control
Abstract
The invention discloses a control system of a gas bearing type centrifugal compressor, and relates to the technical field of compressors. The compressor adopts an auxiliary gas pressurization injection flow regulating valve or a gas bearing type centrifugal compressor adopting an auxiliary liquid pump to supply liquid, and is applied to a refrigeration system, each mode is used for controlling the stable gas supply pressure difference of a gas bearing, the pressure of an oil groove is balanced to the low-pressure evaporation pressure side through a balance pipe, the oil supply of an oil film bearing is realized after low-pressure lubricating oil is lifted to higher pressure through the action of an oil pump, the oil supply pressure difference is the difference value of the oil supply pressure and the evaporation pressure, so the control target of the refrigeration system is to keep the outlet water temperature of chilled water stable, namely the evaporation pressure is stable, and the pressure of the oil groove is always stable.
Description
Technical Field
The invention relates to the technical field of compressors, in particular to a control system of a gas bearing type centrifugal compressor.
Background
The principle of the gas bearing is the same as that of the oil film bearing, and the gas bearing and the oil film bearing are designed by high-pressure dynamic pressure oil films or high-pressure dynamic pressure gas films. The high-pressure oil supply enters the bearing or the high-pressure air supply enters the bearing to form a stable dynamic pressure oil film or air film, the thickness of the dynamic pressure oil film, the wedge angle of an oil film surface of the thrust bearing, the wedge angle of an oil film ring of the radial bearing, the eccentric angle and the eccentricity of the shaft/bearing, and the rigidity and the damping of the oil film have self-adaptive stability characteristics, so that the stable bearing and the operation of a shafting are ensured. The dynamic pressure bearing is applied to a centrifugal compressor and a refrigerating system, and due to the fluctuation of exhaust pressure and suction pressure caused by the change of operating conditions, the variable operating conditions deviate from the designed operating conditions to operate; meanwhile, due to the change of the air conditioner load, the compressor needs to unload and reduce the rotating speed, and the variable load deviates from the designed working condition to operate; the variable working condition and the variable load are operated, the generated axial radial load (aiming at a radial bearing) and the axial load (aiming at a thrust bearing) are in the process of changing at any time, at the moment, the thickness of an air film/oil film, the wedge angle of the oil film/air film surface, the wedge angle of the oil film/air film ring, the eccentric angle and the eccentricity ratio of the axis relative to the center of the bearing are changed, and the rigidity and the damping of the air film and the oil film are also changed so as to automatically adapt to the change of the load and keep the stable operation of a shafting.
In order to realize the design of a high-pressure dynamic pressure oil film bearing or a high-pressure dynamic pressure air film bearing and ensure the axial bearing capacity and the radial bearing capacity of a stable and reliable bearing, an oil film or an air film with stable rigidity and damping is formed between the bearing and a shaft; the supply pressure difference or the supply pressure difference must be constantly controlled, and the supply air temperature must be constantly controlled.
Disclosure of Invention
The present invention is directed to the above technical problems, and provides a control system for a gas bearing type centrifugal compressor, which overcomes the disadvantages of the prior art.
In order to solve the above technical problems, the present invention provides a control system for a gas bearing type centrifugal compressor.
Gas bearings are used in semi-hermetic or open-type centrifugal compressor systems. Fig. 3 and 4 illustrate the use of an auxiliary gas pressurization pilot flow control valve, fig. 5, 6 and 9 illustrate the use of auxiliary liquid pump pressurization, and fig. 7, 8 and 10 illustrate the use of both an auxiliary gas pressurization pilot flow control valve and an auxiliary liquid pump liquid pressurization.
The auxiliary gas pressurization injection flow regulating valve and the auxiliary liquid pump are pressurized, each mode is used for controlling the stable gas supply pressure difference of the gas bearing, and the use significance of the auxiliary gas pressurization injection flow regulating valve and the auxiliary liquid pump is that when the gas supply pressure difference of a refrigeration system meets the requirement of the minimum gas supply pressure difference of the gas bearing, the auxiliary gas pressurization injection flow regulating valve is kept closed, and the auxiliary liquid pump is kept closed; when the minimum supply differential pressure for the gas bearing is not met, the auxiliary liquid pump is activated, or the auxiliary gas pressurization pilot flow regulator valve is opened, to provide additional pressurization supply differential pressure. The booster injection flow regulating valve is a non-power consumption element which leads out a part of gas from the high-pressure exhaust of the compressor, and the opening of the regulating valve with different percentages can change the gas flow and the gas pressure entering the injector 16 and finally change the gas supply pressure difference of the gas bearing; the liquid pump is a power consuming element.
In fig. 1 and 2, the gas in the return manifold 110 of the gas bearing returns to the evaporator of the refrigeration system by means of pressure difference, and the evaporator itself is provided with a pressure sensor 301 for controlling the liquid supply of the two-stage throttle expansion valve 5 and controlling the small temperature difference of the evaporator; the flash evaporator shell is provided with a pressure sensor 302 for controlling the liquid supply of the first-stage throttle expansion valve 4 and the supercooling degree of the condenser. 301 and 302 are pressure sensors that a typical refrigeration system would be equipped with for flow regulation control of the refrigeration system itself. Therefore, in addition to the pressure sensor configured by the existing refrigeration system, a pressure sensor 303 of the liquid discharge end of the liquid pump 7 on the liquid supply circuit 106 and a pressure sensor 304 on the gas supply circuit 107 of the gas bearing are additionally arranged. The gas bearing has a gas supply pressure difference of
The lift of the liquid pump is
Speed of pump
。
First, a minimum supply gas pressure difference of the gas bearing is set
If the pressure difference of the supplied air is insufficient, that is
Then, the liquid pump is started to pressurize liquid or the gas pressurizing injection flow regulating valve is opened to pressurize gas, and under the operation working condition of most of refrigerating systems, when the actual gas supply pressure difference is
When the pressure difference is larger than the set value of the pressure supply pressure difference by 300kPa, the liquid pump or the gas pressurizing injection flow regulating valve does not need to be opened; when the actual air supply pressure difference
Less than 300kPa with the set value of the pressure difference of the air supplyThe liquid pump or the gas pressurization injection flow regulating valve only needs to operate, and the gas or the liquid pressurization finally improves the gas supply pressure of the gas bearing. The liquid pump is started from shutdown to minimum rotating speed operation, so that sudden change of air supply pressure is necessarily generated, air supply flow is also inevitably increased suddenly, bearing characteristics such as load, rigidity and damping of a bearing are changed greatly, normal operation of the centrifugal compressor is influenced, and therefore the variable-frequency liquid pump or the constant-frequency liquid pump is adopted to increase the air supply pressure slowly by adding an internal pressure difference adjusting valve. The principle of the variable frequency liquid pump is simple, the flow rate of the pump is in direct proportion to the square of the rotating speed, the flow rate of the pump and the lift of the pump are in a quadratic curve relation, therefore, the flow rate of the pump and the outlet pressure of the pump are gradually increased along with the gradual increase of the rotating speed from 0, the process is gentle, and the final rotating speed of the pump and the air supply pressure difference of the air bearing are in the quadratic curve relation. Equation (3) is the pump speed
And the gas supply pressure difference of the gas bearing
When different rotating speeds are required to be actually measured to operate, the gas supply pressure difference of the gas bearing can be obtained through nonlinear fitting, and each coefficient of the formula (3) can be obtained
，
，
Different liquid pump types, gas bearing designs, this relationship is different, but the principle and method are the same.
However, the process that the gas pressurization jet flow regulating valve is opened gradually from the closed state by 0% opening degree is relatively gentle, and sudden changes of the gas supply pressure of the gas bearing can be basically and completely avoided. However, the gas supercharging injection flow regulating valve is a small part of high-pressure refrigerant gas led out from the high-pressure exhaust of a compressor of the refrigerating system, does not work, belongs to a passive regulating mechanism, and is relatively stable in regulation; the liquid pump is a working element, belongs to an active adjusting mechanism, has a sudden change in the adjusting process, and can realize a better stable adjusting effect by adopting the variable-frequency liquid pump. The effect is even better if the two are combined, as shown in fig. 7, fig. 8 and fig. 10.
Formula (4) opening degree of gas pressurization jet flow regulating valve
And the gas supply pressure difference of the gas bearing
When the percentage opening (%) of the regulating valve is actually measured, the gas supply pressure difference of the gas bearing is subjected to nonlinear fitting to obtain each coefficient of the formula (4)
，
，
This relationship is different depending on the linear and flow characteristics of the regulator valve, and the design of the gas bearing, but the principle and method are the same.
Further, the opening and closing of the liquid pump: after the liquid pump is started, the air supply pressure is increased, when the air supply pressure difference is also increased, if the air supply pressure difference is greater than the minimum air supply pressure difference set value, the air supply pressure difference is increased until the minimum air supply pressure difference set value is reached
The liquid pump can be shut down again after the satisfaction; similarly, if the liquid pump is turned off, the minimum supply pressure differential will decrease until the liquid pump is turned off
The liquid pump can only be turned on again after this is met. By adopting the setting of the upward return difference and the downward return difference, the liquid pump can be ensured not to be frequently opened and closed according to test measurement, the air supply pressure difference is also ensured to be stabilized in a set small interval, and the bearing works stably.
Further, the opening and closing of the liquid pump is associated with variable frequency control.
The invention has the beneficial effects that:
(1) in the invention, the pressure of the oil groove is balanced to the low-pressure evaporation pressure side through the balance pipe, the low-pressure lubricating oil is lifted to the higher pressure through the action of the oil pump, the oil supply of the oil film bearing is realized, the oil supply pressure difference is the difference value of the oil supply pressure and the evaporation pressure, thus, the control target of the refrigeration system is to keep the outlet water temperature of the chilled water stable, namely the evaporation pressure is stable, the pressure of the oil groove is always stable, the larger stability cannot occur, the pressure in front of the oil pump is lower, and the whole pipeline can also be designed according to the low-pressure.
Drawings
FIG. 1 is a structural layout of a centrifugal compressor with gas bearings;
FIG. 2 is a structural layout of a centrifugal compressor with gas bearings;
FIG. 3 is a flow diagram of a refrigeration system-high pressure liquid phase line draws liquid and pressurizes with gas;
FIG. 4 is a flow diagram of a refrigeration system-medium pressure liquid phase line draws liquid and pressurizes the gas;
FIG. 5 is a flow diagram of a refrigeration system-high pressure liquid phase line draws liquid with a liquid pump;
FIG. 6 is a flow diagram of a refrigeration system-medium pressure liquid phase line draws liquid with a liquid pump;
FIG. 7 is a flow diagram of a refrigeration system-high pressure liquid phase line draws liquid and liquid pump and gas pressurization;
FIG. 8 is a flow diagram of a refrigeration system-medium pressure liquid phase line draws liquid and liquid pump and gas pressurization;
FIG. 9 is a flow diagram of a refrigeration system-low pressure liquid phase line draws liquid and liquid pump;
FIG. 10 is a flow diagram of a refrigeration system-low pressure liquid phase line draws liquid and liquid pump and gas pressurization;
fig. 11 shows the start-stop control of the liquid pump.
Wherein: 1-a centrifugal compressor; 2-a condenser; 3-a flash economizer; 4-first stage throttle expansion valve; 5-a two-stage throttle expansion valve; 6-an evaporator; 7-a liquid pump; 8-impeller end gas radial bearing; 9-non-impeller end gas radial bearing; 10-a thrust bearing; 11-a reverse thrust bearing; 12-a thrust collar; 13-motor/rotor shaft assembly; 14-a motor stator; 15-an impeller; 16-a venturi restrictor; 17-a one-way valve; 18-gas pressurization injection flow regulating valve; 19-impeller tip landing bearing; 20-impeller-end landing bearing 100-exhaust line; 101-an aspiration line; 102-condenser outlet liquid phase line; 103-economizer gas phase line 104-economizer liquid phase line; 105-gas bearing supply manifold 106-liquid pump discharge manifold; 107-gas bearing gas supply manifold; 108-bearing supply distribution line; 109-air supply holes for high-pressure nozzles of each air bearing; 110-gas bearing return manifold; 111-gas pressure boost injection pipeline; (ii) a 112-evaporator draft tube 301-evaporation pressure sensor; 302-an intermediate pressure sensor; 303-a liquid supply pressure sensor; 304-supply air pressure sensor.
Detailed Description
In fig. 1-2, a semi-hermetic centrifugal compressor using a gas bearing is provided, and gas radial bearings 8 and 9 are distributed on two sides of a span of a motor rotor/shaft. Landing bearings 19 and 20 are distributed inside the span of the motor rotor/shaft with a slightly smaller clearance than the gas bearings. Dimension D is the landing bearing clearance, dimension D1 is the gas bearing clearance, D1> D. The impeller end radial bearing 8 and the non-impeller end gas radial bearing 9 provide radial load bearing. The gas thrust bearing 10 provides a positive thrust force towards the impeller end, and when the centrifugal compressor stably operates under various high-low pressure difference working conditions, the direction of the force applied to the shafting caused by gas is towards the non-impeller end, so that the thrust bearing 10 provides the thrust force to overcome the gas force of the shafting. The reverse gas thrust bearing 11 provides a reverse thrust bearing force towards a non-impeller end, when the compressor is under a low-flow and high-pressure-difference working condition, if the compressor is in stall or surge, the exhaust pressure of the compressor will periodically oscillate, the exhaust pressure at the outlet of the impeller will flow backwards to the suction side, and the transient gas force of a compressor shaft system at the moment is a plurality of times of the reverse gas force towards the impeller end, so that the reverse thrust bearing 11 provides a thrust force to overcome the transient gas force of the shaft system. The end surfaces at both sides of the thrust collar 12 rotating with the impeller shaft at high speed respectively face the thrust bearing 10 and the reverse thrust bearing 11 at both sides. The balance between the two bearings ensures axial centering of the shafting.
In fig. 3 and 4, the gas radial bearings 8 and 9, the gas thrust bearings 10 and 11, and their high-pressure gas supply circuits are as follows: from the high-pressure condenser outlet liquid phase pipeline 102 (fig. 3) or the intermediate-pressure economizer liquid phase pipeline 104 (fig. 4), high-pressure refrigerant saturated liquid or supercooled liquid (fig. 3) or intermediate-pressure refrigerant saturated liquid or supercooled liquid (fig. 4) is led out, a small part of liquid enters a liquid supply main 105 of the gas bearing through the liquid supply pipeline 102 (fig. 3) or 104 (fig. 4) due to the driving force of the pressure difference between high pressure and low pressure, a large amount of flash gas of the refrigerant liquid is generated after the refrigerant liquid passes through the venturi restrictor 16, the flow rate of the mixture of the non-flash refrigerant liquid and the flash refrigerant gas is increased, the pressure of the mixture is reduced, the mixture of the non-flash refrigerant liquid and the flash refrigerant gas flows through a gas supply main 107 of the gas bearing at high speed, and then the gas-liquid mixture is respectively distributed to each bearing. A plurality of tiny high-pressure nozzle gas supply holes 109 are arranged on the gas bearings 8-11 in the circumferential direction and the axial direction, the purpose of the high-pressure nozzle gas holes is to completely flash the residual refrigerant liquid in the gas-liquid mixture into gas, finally, the high-pressure gas is supplied into the circumferential wedge-shaped gap of the radial bearing and the surface wedge-shaped gap of the thrust bearing and thrust lantern ring 12, a high-pressure gas film with enough rigidity and damping is formed, and stable gas bearing capacity is formed.
Optionally, in fig. 5 and 6, a gas pressurizing injection gas loop 111 is used. The high-pressure gas is led out from the exhaust pressure side of the compressor through a gas pressurization injection pipeline 111, the high-pressure gas enters the ejector 16 after the flow and the pressure are adjusted through a gas pressurization injection flow adjusting valve 18, when the control system detects that the gas supply pressure difference is insufficient, the flow of the high-pressure gas for injecting pump liquid can be adjusted through the adjusting valve 18, the ejector 16 also has the function of pumping the high-pressure gas, the liquid in the liquid supply pipeline 105 is sucked into the ejector 16 in a pressurization mode and is communicated with the high-pressure gas to enter the gas supply loop 107 of the gas bearing, the flow and the pressure of the gas and the liquid in the gas supply loop 107 are improved, the gas supply pressure difference of the gas bearing is ensured to be stabilized in a range, and the accurate gas supply pressure difference control can be achieved through the linear adjusting function of the.
Alternatively, in fig. 7 and 8, a liquid pump 7 may be disposed on the gas bearing liquid supply manifold 105 to increase the liquid supply pressure, and when the liquid pump is started, the liquid flows through a 106 pipeline and enters a 107 gas supply manifold; when the liquid pump is not activated, it flows through the bypass line 110 into the supply manifold 107. The purpose of the check valve 17 is to ensure that when the liquid pump is not operating, the refrigerant passes through the differential pressure flow line 110 into line 107; and when the liquid pump is operated, the backflow of the fluid is avoided. Finally, the purpose of the liquid pump is to increase the gas supply pressure of the gas bearing when necessary, when the centrifugal compressor has surge operation, or is caused by sudden load change, or is operated under a low pressure difference working condition, the gas supply pressure of the gas bearing is lower and the bearing capacity is smaller only by the driving force of high and low pressure difference of the refrigeration system, the liquid pump can be started, and after the liquid is pressurized, the higher gas supply pressure of the gas bearing is provided, and the bearing capacity of the bearing is increased.
Alternatively, in fig. 9 and 10, the refrigeration system includes a liquid pump 7 and a gas booster circuit 111. More stable and reliable gas supply pressure difference control and stable operation of the gas bearing can be realized. In fig. 11, when the design with the liquid pump is adopted, low-pressure refrigerant liquid can be directly drawn out from the bottom liquid phase region of the evaporator, and the low-pressure refrigerant is raised to a higher refrigerant pressure through the liquid pressurization and gas pressurization injection loop 111 of the liquid pump 7, so that gas supply of the gas bearing is realized. The design is similar to the design of a high-pressure dynamic pressure oil film bearing, the pressure of an oil groove is balanced to the evaporation pressure side of low pressure through a balance pipe, the oil supply of the oil film bearing is realized after low-pressure lubricating oil is lifted to higher pressure through the action of an oil pump, the oil supply pressure difference is the difference value of the oil supply pressure and the evaporation pressure, and thus, the control target of a refrigeration system is to keep the outlet water temperature of the chilled water stable, namely the evaporation pressure is stable, the pressure of the oil groove is always stable, larger stability cannot occur, the pressure in front of the oil pump is lower, and the whole pipeline can also be designed according to the low-pressure. The design of low-pressure liquid injection or liquid pumping is adopted, so that the control angle is stable.
In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.
Claims (4)
1. A control system for a gas bearing centrifugal compressor, characterized by: the compressor adopts an auxiliary gas pressurization injection flow regulating valve or a gas bearing type centrifugal compressor adopting an auxiliary liquid pump to supply liquid, and is applied to a refrigerating system, each mode is used for controlling the stable gas supply pressure difference of a gas bearing, and the use significance of the gas bearing type centrifugal compressor and the gas bearing type centrifugal compressor is that when the gas supply pressure difference of the refrigerating system meets the requirement of the minimum gas supply pressure difference of the gas bearing, the auxiliary gas pressurization injection flow regulating valve is kept closed, and the auxiliary liquid pump is kept closed; when the minimum supply differential pressure for the gas bearing is not met, the auxiliary liquid pump is activated, or the auxiliary gas pressurization pilot flow regulator valve is opened, to provide additional pressurization supply differential pressure.
2. The control system of a gas bearing centrifugal compressor of claim 1, wherein: the compressor adopts a mode of boosting the injection flow regulating valve by auxiliary gas, the opening percentage (%) of the regulating valve can change and regulate the flow of high-pressure gas for injecting liquid, and the ejector 16 also has the function of boosting and sucking the liquid in the liquid supply pipeline 105 into the ejector 16 through the liquid pumping function of the high-pressure gasHigh-pressure gas is communicated with the gas supply loop 107 of the gas bearing, the flow and the pressure of the gas and the liquid in the gas supply loop 107 are improved, and the gas supply pressure difference of the gas bearing is finally improved; formula (4) opening degree of gas pressurization jet flow regulating valve
And the gas supply pressure difference of the gas bearing
When the percentage opening (%) of the regulating valve is actually measured, the gas supply pressure difference of the gas bearing is subjected to nonlinear fitting to obtain each coefficient of the formula (4)
，
，
。
3. The control system of a gas bearing centrifugal compressor of claim 1, wherein: the auxiliary liquid pump adopts a liquid pump with a flow/pressure regulation mode of a variable-frequency liquid pump or a built-in differential pressure flow/pressure regulation mode of a fixed-frequency liquid pump or other variable flow/variable pressure head regulation modes; the change of the rotating speed and the pressure difference adjustment can change the pressure head of the output liquid of the auxiliary liquid pump, output the flow of the liquid and finally adjust the total gas supply pressure and the gas supply pressure difference of the gas bearing, thereby ensuring the stable operation of the gas bearing; the flow rate of the liquid pump is in direct proportion to the square of the rotating speed, and the flow rate of the liquid pump and the pressure head of the liquid pump are in a quadratic curve relationship, so that the flow rate of the liquid pump and the pressure of the pump outlet are gradually increased along with the gradual increase of the rotating speed from 0, which is a relatively gentle process, and the final rotating speed of the liquid pump and the air supply pressure difference of the air bearing are also twoThe relationship of the secondary curves; rotation speed of liquid pump in equation (3)
And the gas supply pressure difference of the gas bearing
When different rotating speeds are required to be actually measured to operate, the gas supply pressure difference of the gas bearing can be obtained through nonlinear fitting, and each coefficient of the formula (3) can be obtained
，
，
。
4. The control system of a gas bearing centrifugal compressor of claim 1, wherein: opening and closing of the auxiliary liquid pump: after the liquid pump is started, the air supply pressure is increased, when the air supply pressure difference is also increased, if the air supply pressure difference is greater than the minimum air supply pressure difference set value, the air supply pressure difference is increased until the minimum air supply pressure difference set value is reached
The liquid pump can be shut down again after the satisfaction; similarly, if the liquid pump is turned off, the minimum supply pressure differential will decrease until the liquid pump is turned off
The liquid pump can be started again after the requirements are met; by adopting the setting of the upward return difference and the downward return difference, the liquid pump can be ensured not to be frequently opened and closed according to test measurement, the air supply pressure difference is also ensured to be stabilized in a set small interval, and the bearing works stably.
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| CN114198922A (en) * | 2021-11-22 | 2022-03-18 | 青岛海尔空调电子有限公司 | Liquid supply system of compressor |
| CN114198920A (en) * | 2021-11-22 | 2022-03-18 | 青岛海尔空调电子有限公司 | Method and device for controlling refrigerant circulation system and refrigerant circulation system |
| CN114198828A (en) * | 2021-11-22 | 2022-03-18 | 青岛海尔空调电子有限公司 | Air suspension unit system and control method |
| CN114198919A (en) * | 2021-11-22 | 2022-03-18 | 青岛海尔空调电子有限公司 | Gas suspension unit system |
| CN114198921A (en) * | 2021-11-22 | 2022-03-18 | 青岛海尔空调电子有限公司 | Method and device for controlling refrigerant circulation system and refrigerant circulation system |
| CN114198923A (en) * | 2021-11-22 | 2022-03-18 | 青岛海尔空调电子有限公司 | Air supply system of compressor |
| CN114198949A (en) * | 2021-11-22 | 2022-03-18 | 青岛海尔空调电子有限公司 | Liquid supply system of compressor |
| CN115751661A (en) * | 2022-11-02 | 2023-03-07 | 青岛海信日立空调系统有限公司 | Oilless bearing liquid supply air conditioning system and control method thereof |
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Effective date of registration: 20221212 Address after: 266555, No. 218, Bay Road, Qingdao economic and Technological Development Zone, Shandong Patentee after: QINGDAO HISENSE HITACHI AIR-CONDITIONING SYSTEMS Co.,Ltd. Address before: 214000 No. 1600, Gao Lang Xi Road, Binhu District, Wuxi, Jiangsu Patentee before: WUXI INSTITUTE OF TECHNOLOGY |