CN108894834B - Automatic monitoring expander oil supply and return system - Google Patents
Automatic monitoring expander oil supply and return system Download PDFInfo
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- CN108894834B CN108894834B CN201810717670.3A CN201810717670A CN108894834B CN 108894834 B CN108894834 B CN 108894834B CN 201810717670 A CN201810717670 A CN 201810717670A CN 108894834 B CN108894834 B CN 108894834B
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 15
- 230000001105 regulatory effect Effects 0.000 claims abstract description 45
- 239000003921 oil Substances 0.000 claims description 250
- 239000010687 lubricating oil Substances 0.000 claims description 94
- 239000007788 liquid Substances 0.000 claims description 35
- 238000010586 diagram Methods 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 8
- 238000005461 lubrication Methods 0.000 claims description 3
- 238000013461 design Methods 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 23
- 238000011084 recovery Methods 0.000 description 17
- 239000012530 fluid Substances 0.000 description 8
- 238000001816 cooling Methods 0.000 description 6
- 239000007791 liquid phase Substances 0.000 description 5
- 230000001050 lubricating effect Effects 0.000 description 5
- 239000002918 waste heat Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000010724 circulating oil Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 235000003642 hunger Nutrition 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000037351 starvation Effects 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000010729 system oil Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/18—Lubricating arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D17/00—Regulating or controlling by varying flow
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
The invention discloses an automatic monitoring expander oil supply and return system, which comprises a work circulation subsystem and an oil supply and return subsystem, wherein the work circulation subsystem comprises an expander, a condenser, a working medium pump and an evaporator which are sequentially and circularly connected, the oil supply and return subsystem comprises an oil-gas separator, an oil storage tank, an oil filter, an oil return pump, a heat regenerator, a first flow regulating valve and a second flow regulating valve which are sequentially connected, an inlet of the oil-gas separator is connected with an outlet of the expander, an outlet of the heat regenerator is connected with an inlet of the expander, one end of the first flow regulating valve is connected between an outlet of the heat regenerator and an inlet of the expander, the other end of the first flow regulating valve is connected with an inlet of the oil storage tank, and the second flow regulating valve is arranged at two ends of the heat regenerator in parallel. The invention has the advantages of simple structure, high degree of automation, simple and efficient design, small occupied space, low economic cost and great application prospect.
Description
Technical Field
The invention relates to the technical field of waste heat recovery, in particular to an expander oil supply and return system capable of being automatically monitored.
Background
Along with the continuous rising of energy demand and energy price and the continuous deterioration of environment, energy conservation and energy recovery have become national development strategies. Organic Rankine Cycle (ORC) has become a research hotspot for a vast number of scholars as a key technology for medium-low temperature waste heat recovery. The operation performance of the expander is greatly influenced on the circulation thermal efficiency of the system, the expander is in a high-speed running state in the working process, enough lubricating oil is needed to lubricate and cool friction pairs of the expander and take away scraps generated in the friction process, and the oil supply and return system of the expander determines the working efficiency and the service life of the expander to a great extent and influences the operation performance and the circulation thermal efficiency of the whole ORC system. The operation efficiency of the expander is directly determined by the quality of the lubricating system of the expander, so that the circulation efficiency of the system is affected. The oil supply and return system of the existing expander cannot accurately control the oil supply pressure, the oil supply temperature and the oil supply quantity of the expander, and a special oil running recovery system is not provided, so that the lubricating effect of the expander is poor, and the heat exchange efficiency of heat exchange equipment in the system is also influenced.
However, research on an oil supply and return system of an expander is lacking at present, and a traditional oil supply and return system of the expander is often simpler, so that accurate monitoring and control on oil supply temperature, oil supply pressure and oil supply flow cannot be realized. Moreover, due to the influence of the separation efficiency of the oil-gas separator, after the oil supply and return system of the traditional expander reaches a certain operation time, a large amount of lubricating oil enters and remains in other parts (mainly heat exchange parts such as a condenser and an evaporator) of the ORC system, so that the heat exchange efficiency of each heat exchange part is reduced, the oil supply of the expander is insufficient, and the operation efficiency of the whole ORC system is further reduced. When the system has serious oil leakage, the traditional expander oil supply and return system cannot recycle the lubricating oil in the system loop, and can only replace working medium and supplement the lubricating oil again, so that the running cost of the ORC system is increased, and the circulation efficiency of the system is gradually reduced along with the accumulation of the running time.
In the prior art, the literature associated with expander lubrication oil systems is relatively lacking. The Chinese patent application with publication number of CN105888731A and application name of lubricating system of organic Rankine cycle single screw expander discloses a lubricating system of organic Rankine cycle single screw expander, which utilizes the mixture of organic Rankine working medium and lubricating oil to be separated into gaseous working medium and liquid lubricating oil in evaporator to complete the lubricating system of organic Rankine cycle single screw expander. Chinese patent application publication No. CN101194084a, entitled "expander lubrication in a steam power system", discloses a steam power generation system for generating power by using heat from a heat source. The system comprises a closed circuit for a working fluid and comprises: a heat exchanger assembly for heating a fluid under pressure using heat from the source; a separator for separating a vapor phase of the heated fluid from a liquid phase thereof; an expander for expanding the steam to generate power; a condenser for condensing the discharge fluid from the expander; a feed pump for returning the condensed fluid from the condenser to the heater; and a return path for returning the liquid phase from the separator to the heater. The liquid phase of the working fluid comprises a lubricant which is soluble or miscible in the liquid phase and a bearing supply passage is arranged for delivering the liquid phase pressurized by the feed pump to at least one bearing for a rotating element of the expander. The above-mentioned prior art has the common disadvantages of: 1. the lubricating oil is directly dissolved in the working medium, and the lubricating oil runs in the whole ORC system along with the working medium, so that part of the lubricating oil stays in each heat exchanger, the heat exchange coefficient of each heat exchange part is reduced, and the oil consumption of the lubricating oil is greatly increased; 2. the oil-gas separator is arranged between the outlet of the evaporator and the inlet of the expander, so that lubricating oil absorbs heat in the evaporator and heats up, then the oil cooler is used for cooling the lubricating oil, and the heat and the cold are mutually offset, so that energy waste is caused; 3. the system lacks a lubricating oil monitoring system and can not accurately detect whether the expander lacks oil; 4. the oil supply pressure of the circulating oil pump cannot be adjusted according to the inlet pressure of the expander, so that the oil pressure is possibly too low or too high, and the oil supply is failed; 5. failure to control the oil supply to the expander can result in the expander being rich or lean.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides an automatic monitoring expander oil supply and return system which can be mainly applied to organic Rankine cycle, accurately supplies oil to an expander, monitors the lubricating oil quantity of the system, and switches to an oil running recovery mode when necessary, so that the safe and efficient operation of the expander is ensured, and meanwhile, the circulating heat efficiency of the system is improved.
The technical scheme adopted for solving the technical problems is as follows: the automatic monitoring expander oil supply and return system comprises a work circulation subsystem and an oil supply and return subsystem, wherein the work circulation subsystem comprises an expander, an oil-gas separator, a condenser, a working medium pump and an evaporator, the expander is connected with the oil-gas separator, the oil-gas separator is connected with the condenser, the condenser is connected with the working medium pump, the working medium pump is connected with the evaporator, the evaporator is connected with the expander, and a heat regenerator is arranged between the working medium pump and the evaporator; the oil supply and return subsystem comprises an oil-gas separator, an oil storage tank, an oil filter, an oil return pump, a heat regenerator, a first flow regulating valve and a second flow regulating valve, wherein the oil-gas separator is connected with the oil storage tank, the oil storage tank is connected with the oil filter, the oil filter is connected with the oil return pump, the oil return pump is connected with the heat regenerator and the expansion machine, the first flow regulating valve is arranged on a pipeline branch connected with one end of the heat regenerator and the expansion machine, the other end of the first flow regulating valve is connected with a pipeline between the oil-gas separator and the oil storage tank, and the second flow regulating valve is arranged on a pipeline branch connected with two ends of the heat regenerator.
The control unit comprises a controller, a photoelectric liquid level sensor, a first temperature sensor, a second temperature sensor, a first pressure sensor, a second pressure sensor, a first thermocouple and a second thermocouple; the photoelectric liquid level sensor is arranged in the oil storage tank, the first temperature sensor and the first pressure sensor are arranged at the inlet of the expander, the second temperature sensor and the second pressure sensor are arranged at the outlet of the expander, the first thermocouple is arranged at the bottom of an oil pool of the expander, and the second thermocouple is arranged at the joint of the first flow regulating valve and the heat regenerator; the photoelectric liquid level sensor, the first temperature sensor, the second temperature sensor, the first pressure sensor, the second pressure sensor, the first thermocouple and the second thermocouple are in data connection with the controller for control, and the controller is in control connection with the oil return pump, the first flow regulating valve and the second flow regulating valve.
The oil recovery control unit comprises a first stop valve, a second stop valve and a third stop valve, wherein the second stop valve is arranged between the evaporator and the expander, the third stop valve is arranged between the expander and the oil-gas separator, the first stop valve is arranged in parallel at the inlet end of the second stop valve and the outlet end of the third stop valve, and the controller is in control connection with the first stop valve, the second stop valve and the third stop valve.
The invention adopts the oil temperature superheat degree as the judging basis of the oil supply condition of the expander, wherein the oil temperature superheat degree is defined as the degree that the lubricating oil temperature in the expander subtracts the saturation temperature of working medium under the working pressure (the high-pressure cavity expander takes the suction pressure and the low-pressure cavity expander takes the exhaust pressure), and the oil temperature superheat degree is a relative value and represents the degree that the lubricating oil exceeds the initial state. The preset oil temperature superheat degree under different working conditions is also different, and the oil temperature superheat degree under different working conditions can be determined by the following circulation experiment method:
s1, arranging an air extractor of an expander, extracting a working medium/lubricating oil mixture in the expander, separating the working medium from the lubricating oil, and calculating the actual solubility of the lubricating oil under the working condition;
s2, according to the running temperature and pressure of the expander, searching a solubility-pressure/temperature diagram to obtain the theoretical solubility of the lubricating oil during normal oil supply;
s3, comparing the theoretical solubility with the actual solubility, and judging whether the theoretical solubility and the actual solubility are close (the approaching range can be determined according to the actual working medium condition);
s4, if the two are close, calculating the oil temperature superheat degree, and taking the oil temperature superheat degree as the preset oil temperature superheat degree of the expander under the working condition, and performing S5; if the deviation of the two values exceeds the preset value, the oil supply quantity is adjusted to be close to the theoretical solubility, and then S1 is returned;
s5, changing the operation pressure and the operation temperature of the expander, returning to S1, performing a circulation experiment, and finally drawing a preset oil temperature superheat degree-pressure/temperature diagram under each working condition.
The working process of the invention comprises the following steps:
1. normal oil supply mode of expander: when the photoelectric liquid level sensor detects that the liquid level in the oil storage tank exceeds a preset minimum liquid level, the working circulation subsystem and the oil supply and return subsystem work normally; the lubricating oil flows out of the oil storage tank, enters the oil pump after passing through the oil filter, and provides circulating flow power for the lubricating oil, and the controller controls the oil supply pressure by changing the operating frequency of the oil pump according to the first pressure sensor (the inlet pressure of the expander); then, the lubricating oil reaching the preset oil supply pressure is divided into two paths, one path enters the heat regenerator to cool, the other path passes through the first flow regulating valve and is mixed with the cooled lubricating oil at the outlet of the heat regenerator, and the controller regulates the opening of the second flow control valve according to the temperature value fed back by the second thermocouple, so that the flow of the lubricating oil participating in heat exchange is controlled, and the oil supply temperature is controlled; the controller determines oil supply quantity according to a preset oil temperature superheat degree-pressure/temperature diagram, so that part of redundant lubricating oil returns to the oil storage tank through the first flow control valve, and the other part of lubricating oil is conveyed to the inlet of the expander and enters the main bearing and each friction pair of the expander after being mixed with working medium; finally, the lubricated lubricating oil/working medium mixture enters an oil-gas separator for separation, the separated gaseous working medium enters a condenser, and the liquid lubricating oil returns to an oil storage tank to start a new cycle;
2. running oil recovery mode: when the photoelectric liquid level sensor detects that the liquid level in the oil storage tank is lower than the preset minimum liquid level, the system is switched to an oil running recovery mode: at this time, the controller controls the oil pump to stop, and simultaneously controls the first stop valve to be opened, controls the second stop valve and the third stop valve to be closed, and increases the working medium pump stroke, so that the flow of the working cycle subsystem is increased. The working medium carrying lubricating oil sequentially passes through the condenser, the working medium pump, the heat regenerator and the evaporator at a higher flow rate, then enters the oil-gas separator after passing through the first stop valve, and the separated lubricating oil returns to the oil storage tank again, and the gaseous working medium enters the condenser and enters the next cycle. Since the expander is in an open circuit state, the lubricating oil remaining in the oil supply and return subsystem is slowly recovered into the oil storage tank.
Compared with the prior art, the invention has the beneficial effects that: the oil supply temperature, the oil supply pressure and the oil supply quantity of the lubricating oil are accurately regulated and controlled, the expansion machine is ensured to stably and efficiently run under the proper oil supply quantity, and meanwhile, the oil running quantity is maintained at a lower level; in addition, the lubricating oil remained in other parts outside the expander can be effectively recovered, namely, the running cost is reduced, and the circulating heat efficiency is also improved; the equipment has the advantages of simple structure, high automation degree, electric power saving, simple and efficient whole design, good manufacturability, small occupied space, low economic cost and great engineering application prospect.
Drawings
FIG. 1 is a block diagram of the overall structure of an automatically monitorable expander oil supply and return system of the present invention;
FIG. 2 is a block diagram showing the connection of a control unit of an automatic monitoring expander oil supply and return system according to the present invention;
FIG. 3 is a flow chart of a method for determining the superheat of the oil temperature in an oil supply and return system of an expander capable of being automatically monitored;
FIG. 4 is a schematic diagram illustrating the operation of the automatic monitoring expander oil supply and return system in the normal oil supply mode according to the present invention;
FIG. 5 is a schematic diagram of the operation of the present invention in an automatic monitoring mode for the oil recovery of the oil supply and return system of the expander.
Detailed Description
The invention will be further described with reference to the accompanying drawings, in which arrows indicate the media processing direction.
The automatic monitoring expander oil supply and return system is mainly applied to the organic Rankine cycle, accurately supplies oil to the expander, monitors the lubricating oil quantity of the system, and switches to an oil running recovery mode if necessary, so that the safe and efficient operation of the expander is ensured, and meanwhile, the circulating heat efficiency of the system is improved. The working cycle system comprises a working cycle subsystem and an oil supply and return subsystem, wherein the working cycle subsystem comprises an expansion machine 13, an oil-gas separator 2, a condenser 5, a working medium pump 8 and an evaporator 11, the expansion machine 13 is connected with the oil-gas separator 2, the oil-gas separator 2 is connected with the condenser 5, the condenser 5 is connected with the working medium pump 8, the working medium pump 8 is connected with the evaporator 11, the evaporator 11 is connected with the expansion machine 13, and the components are sequentially connected in series to form a basic ORC system. A regenerator 9 is arranged between the working fluid pump 8 and the evaporator 11. The oil supply and return subsystem comprises an oil-gas separator 2, an oil storage tank 3, an oil filter 6, an oil return pump 7, a heat regenerator 9, a first flow regulating valve FV1 and a second flow regulating valve FV2, wherein the oil-gas separator 2 is connected with the oil storage tank 3, the oil storage tank 3 is connected with the oil filter 6, the oil filter 6 is connected with the oil return pump 7, the oil return pump 7 is connected with the heat regenerator 9 and the expansion machine 13, and the first flow regulating valve FV1 is arranged on a pipeline branch with one end connected with a pipeline between the heat regenerator 9 and the expansion machine 13 and the other end connected with a pipeline between the oil-gas separator 2 and the oil storage tank 3. The second flow regulating valve FV2 is mounted on a pipe branch connected to both ends of the regenerator 9. The regenerator 9 is provided with a heat exchanger. A working medium channel and a lubricating oil channel are arranged in the heat regenerator 9, two ends of the lubricating oil channel are respectively connected with the oil return pump 7 and the expander 13, and two ends of the working medium channel are respectively connected with the working medium pump 8 and the evaporator 11. The oil return pump 7 is a variable frequency oil pump and is provided with a frequency converter V/F, and the regulation and control of the oil supply pressure can be realized by changing the frequency of the frequency converter. The oil-gas separator 2 is arranged at the outlet of the expander 13 and is used for separating gaseous working medium from liquid lubricating oil. An oil storage tank 3 is located after the oil separator 2 for storing lubricating oil of the system. The outlet of the heat regenerator 9 is connected with the inlet of the expansion machine 13, one end of the first flow regulating valve FV1 is connected between the outlet of the heat regenerator 9 and the inlet of the expansion machine 13, and the other end of the first flow regulating valve FV1 is connected with the inlet of the oil storage tank 3. The second flow regulating valve FV2 is installed at two ends of the heat regenerator 9 in parallel to control the oil quantity entering the heat regenerator 9.
The oil-gas separator 2 is provided with a working medium outlet and a lubricating oil outlet, the working medium outlet is connected with the condenser 5 through a working medium pipeline, and the lubricating oil outlet is connected with the oil storage tank 3; the heat regenerator 9 is internally provided with a working medium channel and a lubricating oil channel, two ends of the lubricating oil channel are respectively connected with the oil return pump 7 and the expander 13, two ends of the working medium channel are respectively connected with the working medium pump 8 and the evaporator 11, and high-temperature lubricating oil enters the lubricating oil channel of the heat regenerator 9 to exchange heat with low-temperature working medium in the working medium channel, so that the oil temperature is reduced.
As shown in fig. 2, a control unit is further included, and the control unit includes a controller 1, a photoelectric liquid level sensor 4, a first temperature sensor 18, a second temperature sensor 16, a first pressure sensor 15, a second pressure sensor 17, a first thermocouple 12, and a second thermocouple 10. The photoelectric liquid level sensor 4 is installed in the oil storage tank 3, and whether the oil level in the oil storage tank 3 reaches the preset minimum oil level is judged by utilizing the photoelectric conversion principle of the photoelectric liquid level sensor 4. The first temperature sensor 18 and the first pressure sensor 15 are arranged at the inlet of the expander 13, the second temperature sensor 16 and the second pressure sensor 17 are arranged on a working medium pipeline at the outlet of the expander 13, the first thermocouple 12 is arranged at the bottom wall surface of an oil pool of the expander 13, and the second thermocouple 10 is arranged at the connection intersection of the first flow regulating valve FV1 and the regenerator 9 (the oil supply position of the expander 13); the photoelectric liquid level sensor 4, the first temperature sensor 18, the second temperature sensor 16, the first pressure sensor 15, the second pressure sensor 17, the first thermocouple 12 and the second thermocouple 10 are in data connection with the controller 1 through an encoder (data acquisition device) 14, and the controller 1 is in control connection with the oil return pump 7, the first flow regulating valve FV1 and the second flow regulating valve FV2.
The photoelectric oil level sensor 4 is arranged at the preset lowest liquid level of the oil storage tank 3 and consists of an infrared emitter and a receiving plate, when the oil level is lower than the preset lowest oil level (namely, the installation position of the photoelectric oil level sensor), the emitted light of the infrared emitter directly penetrates through air instead of lubricating oil, and the change generates an electric signal to indicate that the liquid level of the oil storage tank 3 is too low and transmits the electric signal to the encoder (data collector) 14 to serve as a starting basis of a system oil running mode; the oil return pump 7 is arranged in front of the heat regenerator 9, the pressure at the inlet of the expander 13 is used as a control basis, and the change of the pressure at the outlet of the oil return pump 7 can be realized by changing the operating frequency of the oil return pump 7 so as to adapt to different working conditions; the regenerator 9 serves as a cooling heat exchanger for lubricating oil by utilizing the cooling capacity of the working medium at the outlet of the working medium pump, and the heat of the lubricating oil can be recovered as a part of the waste heat.
The oil leakage recovery control unit comprises a first stop valve SV1, a second stop valve SV2 and a third stop valve SV3, wherein the second stop valve SV2 is arranged on a working medium pipeline between the evaporator 11 and the expander 13, the third stop valve SV3 is arranged on a working medium pipeline between the expander 13 and the oil-gas separator 2, and the first stop valve SV1 is arranged between an inlet end of the second stop valve SV2 and an outlet end of the third stop valve SV3 and is arranged in parallel with the second stop valve SV2 and the third stop valve SV 3. The controller 1 is connected with the first stop valve SV1, the second stop valve SV2 and the third stop valve SV3, and the first stop valve (the electric stop valve) SV1, the second stop valve SV2 and the third stop valve (the working medium loop bypass valve) SV3, the oil-gas separator 2, the oil storage tank 3 with the photoelectric oil level sensor 4, the working medium pump 8, the evaporator 11 and the condenser 5 form an oil leakage recovery subsystem of the whole system.
As shown in fig. 3, the invention adopts the oil temperature superheat degree as the judging basis of the oil supply condition of the expander, wherein the oil temperature superheat degree is defined as the temperature of the lubricating oil in the expander minus the saturation temperature of working medium under the working pressure (the suction pressure is taken by the high-pressure cavity expander, the exhaust pressure is taken by the low-pressure cavity expander), and the oil temperature superheat degree is a relative value and represents the degree of the lubricating oil exceeding the initial state. The preset oil temperature superheat degree under different working conditions is also different, and the oil temperature superheat degree under different working conditions can be determined by the following circulation method:
s1, arranging an air extractor of an expander, extracting a working medium/lubricating oil mixture in the expander, separating the working medium from the lubricating oil, and calculating the actual solubility of the lubricating oil under the working condition;
s2, according to the running temperature and pressure of the expander, searching a solubility-pressure/temperature diagram to obtain the theoretical solubility of the lubricating oil during normal oil supply;
s3, comparing the theoretical solubility with the actual solubility, and judging whether the theoretical solubility and the actual solubility are close to ();
s4, if the two are close, calculating the oil temperature superheat degree, and taking the oil temperature superheat degree as the preset oil temperature superheat degree of the expander under the working condition, and performing S5; if the deviation of the two values exceeds the preset value, the oil supply quantity is adjusted to be close to the theoretical solubility, and then S1 is returned;
s5, changing the operation pressure and the operation temperature of the expander, returning to S1, performing a circulation test, and finally drawing a preset oil temperature superheat degree-pressure/temperature diagram under each working condition.
The working process of the invention is as follows:
1. normal oil supply mode of expander: as shown in fig. 4, when the photoelectric liquid level sensor 4 detects that the liquid level in the oil storage tank 3 exceeds the preset minimum liquid level, the oil supply subsystem and the oil return subsystem work normally; the lubricating oil flows out of the oil storage tank 3, passes through the oil filter 6 and then enters the oil return pump 7, the oil return pump 7 provides circulating flow power for the lubricating oil, and the controller 1 controls the oil supply pressure by changing the operating frequency of the oil return pump 7 according to the first pressure sensor 18 (measuring the inlet pressure of the expander); then, the lubricating oil reaching the preset oil supply pressure is divided into two paths, one path enters the heat regenerator 9 for cooling, the other path passes through the first flow regulating valve FV1 and is mixed with the cooled lubricating oil at the outlet of the heat regenerator 9, and the controller 1 regulates the opening degree of the second flow regulating valve FV2 according to the temperature value fed back by the second thermocouple 10, so that the flow of the lubricating oil participating in heat exchange is controlled, and the oil supply temperature is controlled; the controller 1 determines oil supply quantity according to a preset oil temperature superheat degree-pressure/temperature diagram, so that part of redundant lubricating oil returns to the oil storage tank 3 through the first flow control valve FV1, and the other part of lubricating oil is conveyed to the inlet of the expander 13, mixed with working medium and then enters the main bearing and each friction pair of the expander 13; finally, the lubricated lubricating oil/working medium mixture enters the oil-gas separator 2 for separation, the separated gaseous working medium enters the condenser 5, and the liquid lubricating oil returns to the oil storage tank 3 to start a new cycle.
In the operation process of the oil supply and return mode of the expander 13, the data collector 14 collects the thermocouple temperature value at the bottom oil pool of the expander 13 and the pressure value at the outlet/inlet of the expander (depending on the type of the expander 13, the high-pressure cavity expander 13 takes the suction pressure, the low-pressure cavity expander 13 is like the inlet pressure) and transmits the signals to the controller 1, and the controller 1 obtains the superheat degree of the oil temperature after operation treatment, so that the superheat degree of the oil temperature is used as the control basis of the oil supply quantity, and the opening degree of the first flow regulating valve FV1 is regulated and controlled; the oil return pump 7 takes the inlet pressure of the expander 13 as a control basis, and adjusts the operating frequency of the oil return pump 7 to enable the oil supply pressure to be slightly higher than the inlet pressure of the expander 13; the oil supply temperature of the lubricating oil is controlled between 30 ℃ and 50 ℃, so that the control system controls the opening degree of the second flow regulating valve FV2 by analyzing the temperature values of thermocouples (the first thermocouple 12 and the second thermocouple 10) at the oil supply position, and the lubricating oil quantity entering the heat regenerator 9 is controlled, so that the oil supply temperature is controlled.
2. Running oil recovery mode: as shown in fig. 5, when the photoelectric liquid level sensor 4 detects that the liquid level in the oil storage tank 3 is lower than the preset minimum liquid level, the system switches to the oil running recovery mode, and the oil return subsystem stops working. At this time, the controller 1 controls the return pump 7 to stop, simultaneously controls the first stop valve SV1 to open, controls the second stop valve SV2 and the third stop valve SV3 to close, and increases the stroke of the working fluid pump 8 to increase the flow rate of the oil supply subsystem. The working medium carrying lubricating oil sequentially passes through the condenser 5, the working medium pump 8, the heat regenerator 9 and the evaporator 11 at a higher flow rate, then passes through the first stop valve SV1 and then enters the oil-gas separator 2, the separated lubricating oil returns to the oil storage tank 3 again, and the gaseous working medium enters the condenser 5 and enters the next cycle. Since the expander 13 is in the open state, the lubricating oil remaining in the work circulation subsystem is slowly recovered into the oil tank 1.
Compared with the prior art, the invention has the advantages that:
1. the heat regenerator is arranged at the outlet of the oil return pump 5, and the cooling capacity of the working medium at the outlet of the working medium pump is utilized to cool lubricating oil, so that an oil cooler is omitted, heat released in the cooling process of the lubricating oil can be recovered as a part of waste heat, the preheating of the working medium before entering the evaporator is realized, the heat exchange area of the evaporator is further reduced, and the heat exchange efficiency is improved;
2. the variable-frequency oil pump is adopted by the oil return pump, so that the oil supply pressure can be automatically regulated and controlled, the adaptability to various variable working conditions of the ORC is strong, and the oil supply pressure is effectively prevented from being too low or too high due to the change of the inlet pressure of the expander;
3. a bypass loop provided with a second flow regulating valve FV2 is arranged on the heat regenerator, and the quantity of lubricating oil entering the heat regenerator is controlled through an electric regulating valve on the loop, so that the oil supply temperature of the lubricating oil is controlled (generally 30-50 ℃);
4. a bypass loop provided with a first flow regulating valve FV1 is arranged at the oil supply position of the expander, and the controller judges the oil supply condition (oil enrichment/oil shortage) of the expander according to data fed back by the data acquisition system, so that an electric stop valve on the expander is regulated to realize the control of oil supply;
5. the oil storage tank is provided with a photoelectric oil level sensor, and when the oil level in the oil storage tank is lower than the set minimum oil level, the photoelectric oil level sensor transmits the generated electric signal to the data acquisition device and triggers an alarm;
6. the oil temperature superheat degree is used as the basis for judging the oil enrichment/starvation of the expander, and is defined as the oil temperature minus the saturation temperature of working medium working under the pressure, and is used for representing the temperature value of the lubricating oil exceeding the initial state. The oil temperature superheat degree can reasonably reflect the oil supply condition of the expander;
7. the expander is provided with a bypass circuit provided with a first stop valve SV1, and recovery work of oil running is realized through 3 electric stop valves in the system. When the controller receives the electric signal from the photoelectric oil level sensor, the controller is switched to an oil running recovery mode, so that the mixture of the working medium and the lubricating oil avoids the expander and directly passes through the bypass valve, and the recovery efficiency of the lubricating oil is improved.
The foregoing description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, i.e., the invention is not limited to the specific embodiments described herein, but is to be accorded the full scope of the claims.
Claims (5)
1. The automatic monitoring expander oil supply and return system is characterized by comprising a work circulation subsystem, an oil supply and return subsystem and a control unit, wherein the work circulation subsystem comprises an expander, an oil-gas separator, a condenser, a working medium pump and an evaporator, the expander is connected with the oil-gas separator, the oil-gas separator is connected with the condenser, the condenser is connected with the working medium pump, the working medium pump is connected with the evaporator, the evaporator is connected with the expander, and a heat regenerator is arranged between the working medium pump and the evaporator; the oil supply and return subsystem comprises an oil-gas separator, an oil storage tank, an oil filter, an oil return pump, a heat regenerator, a first flow regulating valve and a second flow regulating valve, wherein the oil-gas separator is connected with the oil storage tank, the oil storage tank is connected with the oil filter, the oil filter is connected with the oil return pump, the oil return pump is connected with the heat regenerator and the expansion machine, the first flow regulating valve is arranged on a pipeline branch connected with a pipeline between the heat regenerator and the expansion machine at one end and a pipeline between the oil-gas separator and the oil storage tank at the other end, and the second flow regulating valve is arranged on a pipeline branch connected with two ends of the heat regenerator; the control unit comprises a controller, a photoelectric liquid level sensor, a first temperature sensor, a first pressure sensor, a first thermocouple, a second thermocouple, a first stop valve, a second stop valve and a third stop valve, wherein the photoelectric liquid level sensor is arranged in the oil storage tank, the first temperature sensor and the first pressure sensor are arranged at an inlet of the expander, the first thermocouple is arranged at the bottom of an oil pool of the expander, and the second thermocouple is arranged at the joint of the first flow regulating valve and the heat regenerator; the photoelectric liquid level sensor, the first temperature sensor, the first pressure sensor, the first thermocouple and the second thermocouple are in data connection with the controller for control, the controller is in control connection with the oil return pump, the first flow regulating valve and the second flow regulating valve, the second stop valve is arranged between the evaporator and the expander, the third stop valve is arranged between the expander and the oil-gas separator, the first stop valve is arranged at the inlet end of the second stop valve and the outlet end of the third stop valve in parallel, and the controller is in control connection with the first stop valve, the second stop valve and the third stop valve;
when the photoelectric liquid level sensor detects that the liquid level in the oil storage tank exceeds a preset minimum liquid level, the working circulation subsystem and the oil supply and return subsystem work normally; the lubricating oil flows out of the oil storage tank, enters the oil pump after passing through the oil filter, and provides circulating flow power for the lubricating oil, and the controller controls the oil supply pressure by changing the operating frequency of the oil return pump according to the pressure value fed back by the first pressure sensor; then, the lubricating oil reaching the preset oil supply pressure is divided into two paths, one path enters the heat regenerator to cool, the other path passes through the first flow regulating valve and is mixed with the cooled lubricating oil at the outlet of the heat regenerator, the controller regulates the opening degree of the second flow regulating valve according to the temperature value fed back by the second thermocouple so as to control the flow rate of the lubricating oil participating in heat exchange, the redundant lubricating oil returns to the oil storage tank through the first flow regulating valve, the other part of lubricating oil is conveyed to the inlet of the expander, the lubricating oil/working medium mixture after lubrication in the expander enters the oil-gas separator to be separated, the separated gaseous working medium enters the condenser, the liquid lubricating oil returns to the oil storage tank and starts a new cycle.
2. The automatic monitoring expander oil supply and return system according to claim 1, wherein the oil-gas separator is provided with a working medium outlet and a lubricating oil outlet, the working medium outlet is connected with the condenser, and the lubricating oil outlet is connected with the oil storage tank.
3. The automatic monitoring expander oil supply and return system according to claim 1, wherein a working medium channel and a lubricating oil channel are arranged in the heat regenerator, two ends of the lubricating oil channel are respectively connected with the oil return pump and the expander, and two ends of the working medium channel are respectively connected with the working medium pump and the evaporator.
4. The automatic monitoring expander oil supply and return system according to claim 1, wherein when the photoelectric liquid level sensor detects that the liquid level in the oil storage tank is lower than a preset minimum liquid level, the controller controls the oil pump to stop, simultaneously controls the first stop valve to be opened, controls the second stop valve and the third stop valve to be closed, working medium carrying lubricating oil in the working cycle subsystem sequentially passes through the condenser, the working medium pump, the regenerator and the evaporator, then enters the oil-gas separator after passing through the first stop valve, the separated lubricating oil returns to the oil storage tank again, and the gaseous working medium enters the condenser to enter the next cycle.
5. The automatically monitorable expander oil supply and return system of claim 4 wherein the superheat of the oil temperature under different conditions is determined by the method steps of:
s1, arranging an air extractor of an expander, extracting a working medium/lubricating oil mixture in the expander, separating the working medium from the lubricating oil, and calculating the actual solubility of the lubricating oil under the working condition;
s2, according to the running temperature and pressure of the expander, searching a solubility-pressure/temperature diagram to obtain the theoretical solubility of the lubricating oil during normal oil supply;
s3, comparing the theoretical solubility with the actual solubility, and judging whether the theoretical solubility and the actual solubility are close or not;
s4, if the two are close, calculating the oil temperature superheat degree, and taking the oil temperature superheat degree as the preset oil temperature superheat degree of the expander under the working condition; if the deviation exceeds the preset value, the oil supply amount is adjusted to be close to the theoretical solubility, and the process returns to S1.
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| CN110230768A (en) * | 2019-07-04 | 2019-09-13 | 电子科技大学中山学院 | New forms of energy electric automobile's driving motor lubricating system |
| CN112392556B (en) * | 2019-08-13 | 2024-05-03 | 江苏国富氢能技术装备股份有限公司 | Annular turbine expansion system for low-temperature gas liquefaction |
| CN111894692B (en) * | 2020-08-03 | 2022-11-25 | 河北亚迎科技有限公司 | A monitoring system for secondary utilization of industrial waste heat |
| CN113473822B (en) * | 2021-09-01 | 2021-11-23 | 中兴通讯股份有限公司 | Two-phase liquid cooling test system and method |
| CN114211934B (en) * | 2021-12-28 | 2024-04-09 | 上海马勒热系统有限公司 | Heat pump air conditioning system of electric automobile |
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