CN114718680A - Supercritical CO integrated with multistage compression heat pump2Cogeneration system and method - Google Patents
Supercritical CO integrated with multistage compression heat pump2Cogeneration system and method Download PDFInfo
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- 230000006835 compression Effects 0.000 title claims abstract description 67
- 238000007906 compression Methods 0.000 title claims abstract description 67
- 238000000034 method Methods 0.000 title claims description 12
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 110
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 55
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 55
- 238000010248 power generation Methods 0.000 claims abstract description 32
- 239000002918 waste heat Substances 0.000 claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 230000001105 regulatory effect Effects 0.000 claims description 8
- 230000003247 decreasing effect Effects 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 4
- 230000002427 irreversible effect Effects 0.000 abstract description 4
- 230000000712 assembly Effects 0.000 abstract 1
- 238000000429 assembly Methods 0.000 abstract 1
- 238000001704 evaporation Methods 0.000 description 11
- 230000008020 evaporation Effects 0.000 description 11
- 230000005494 condensation Effects 0.000 description 4
- 238000009833 condensation Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
- F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
- F01K25/10—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours the vapours being cold, e.g. ammonia, carbon dioxide, ether
- F01K25/103—Carbon dioxide
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K11/00—Plants characterised by the engines being structurally combined with boilers or condensers
- F01K11/02—Plants characterised by the engines being structurally combined with boilers or condensers the engines being turbines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K17/00—Using steam or condensate extracted or exhausted from steam engine plant
- F01K17/02—Using steam or condensate extracted or exhausted from steam engine plant for heating purposes, e.g. industrial, domestic
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K3/00—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein
- F01K3/18—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein having heaters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
- F01K7/32—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines using steam of critical or overcritical pressure
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P80/00—Climate change mitigation technologies for sector-wide applications
- Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
- Y02P80/15—On-site combined power, heat or cool generation or distribution, e.g. combined heat and power [CHP] supply
Abstract
The invention provides supercritical CO integrated with a multi-stage compression heat pump2The combined heat and power generation system comprises a supercritical carbon dioxide cycle power generation system, wherein the outlet of a main compressor is sequentially communicated with a low-temperature heat regenerator, a high-temperature heat regenerator, a boiler and a turbine, and the outlet of a precooler is communicated with the inlet of the main compressor; the outlet of the auxiliary compressor is communicated with the outlet of the cold side of the low-temperature regenerator; the multistage compression heat pump assemblies in the heating system are connected in series step by stepThe hot end is communicated with the supercritical carbon dioxide cycle power generation system, and the cold end of the multi-stage compression heat pump assembly is communicated with the condenser. According to the invention, the multi-stage compression heat pump is adopted to recover the waste heat at the cold end, so that the irreversible heat transfer loss is greatly reduced, the energy is utilized in a graded manner according to the quality, and the energy utilization efficiency of the system is greatly improved. In addition, the invention can realize thermoelectric decoupling, thereby greatly improving the operation flexibility of the system.
Description
Technical Field
The invention belongs to the technical field of power generation, and relates to supercritical CO integrated with a multistage compression heat pump2Cogeneration systems and methods.
Background
The supercritical carbon dioxide power cycle system is expected to replace the traditional steam Rankine cycle by virtue of the advantages of high heat efficiency, compact structure, low investment, low operation and maintenance cost and the like, and greatly improves the power generation efficiency of the coal-fired unit, thereby reducing the emission of pollutants and carbon dioxide. However, the cold end heat release temperature of the supercritical carbon dioxide power cycle power generation system is high, the temperature of the working medium at the inlet of the cooler is above 90 ℃, and the part of heat is taken away by the cooling medium and released to the environment, so that a large amount of energy loss is caused. In order to reduce the loss of the cooling source, it has been proposed by the scholars to couple a compression heat pump at the cold end for heating. Although the inlet working medium temperature of the precooler is higher, the outlet temperature is lower and is about 32 ℃. In order to fully recover the cold-end waste heat, the single-stage heat pump evaporation temperature needs to be lower than the temperature of the working medium at the inlet of the precooler, so that the evaporation temperature is lower, the COP (coefficient of performance) of the heat pump is lower, the power consumption of the heat pump is increased, and the utilization level of the cold-end waste heat is lower.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides supercritical CO integrated with a multi-stage compression heat pump2The cogeneration system and the cogeneration method can effectively reduce the heat exchange temperature difference between the cold-end working medium and the heat pump evaporation working medium, reduce the irreversible heat transfer loss, and effectively improve the COP of the heat pump, thereby greatly improving the utilization level of the waste heat at the cold end of the system。
The invention is realized by the following technical scheme:
supercritical CO integrated with multistage compression heat pump2The cogeneration system comprises a supercritical carbon dioxide circulation power generation system and a heat supply system;
the supercritical carbon dioxide cycle power generation system comprises a main compressor, a low-temperature heat regenerator, a high-temperature heat regenerator, a boiler, a turbine, a precooler and an auxiliary compressor, wherein the outlet of the main compressor is sequentially communicated with the low-temperature heat regenerator, the high-temperature heat regenerator, the boiler and the turbine, and the outlet of the precooler is communicated with the inlet of the main compressor; the inlet of the auxiliary compressor is communicated with the hot side outlet of the low-temperature heat regenerator, and the outlet of the auxiliary compressor is communicated with the cold side outlet of the low-temperature heat regenerator;
the heat supply system comprises a multi-stage compression heat pump assembly and a condenser, the multi-stage compression heat pump assembly is connected in series step by step, and a hot end inlet of the multi-stage compression heat pump assembly is communicated with a hot side outlet of a low-temperature heat regenerator of the supercritical carbon dioxide cycle power generation system; and the hot end outlet of the multi-stage compression heat pump assembly is communicated with a main compressor of the supercritical carbon dioxide circulating power generation system, and the cold end of the multi-stage compression heat pump assembly is communicated with a condenser.
Preferably, the multi-stage compression heat pump assembly comprises N stages of evaporators and N stages of compressors, wherein N is a positive integer and is more than or equal to 2, the adjacent evaporators and the adjacent compressors are connected in series, a cold side outlet of a first stage evaporator (9) is communicated with an inlet of a first stage compressor (16), an outlet of the first stage compressor (16) is communicated with an inlet of a condenser (17), a hot side outlet of the first stage evaporator (9) is communicated with a hot side inlet of a second stage evaporator (10), a hot side inlet of the first stage evaporator (9) is communicated with a hot side outlet of a low-temperature regenerator (2) of the supercritical carbon dioxide cycle power generation system, a cold side outlet of an Nth stage evaporator is communicated with an inlet of the Nth stage compressor, a cold side inlet of the Nth evaporator is communicated with a cold side outlet of an N-1 stage evaporator, and a hot side outlet of the Nth stage evaporator is connected with a main compressor (1) of the supercritical carbon dioxide cycle power generation system The method is simple.
Preferably, a flow regulating valve is arranged between the low-temperature heat regenerator and the first-stage evaporator.
Preferably, a pressure throttle valve is arranged at the cold side inlet of each stage of evaporator.
Preferably, the multi-stage compression heat pump assembly comprises at least two evaporators and two compressors.
Preferably, the working medium at the hot side in the multistage evaporator is carbon dioxide, and the working medium at the cold side in the multistage evaporator is an organic working medium.
Preferably, the organic working fluid comprises at least one of R410A, R407C and R134 a.
Preferably, the working pressure in the multistage evaporator is gradually decreased; and the temperature of the recovered cold-end waste heat in the multistage evaporator is gradually decreased.
Preferably, the condenser supplies heat to a heat consumer.
Supercritical CO integrated with multistage compression heat pump2A cogeneration method, comprising, in combination,
in a non-heating period, after a supercritical carbon dioxide working medium is boosted by a main compressor, the supercritical carbon dioxide working medium absorbs heat in a low-temperature heat regenerator, a high-temperature heat regenerator and a boiler in sequence and then enters a turbine to do work, the carbon dioxide working medium after doing work is released heat in the high-temperature heat regenerator and the low-temperature heat regenerator and then is divided into two strands, one strand is cooled by a cooler and then enters the main compressor to form a closed power generation circulating system, and the other strand is compressed by an auxiliary compressor and then converges to an outlet at the cold side of the low-temperature heat regenerator;
in the heating period, part of carbon dioxide working medium shunted by the outlet at the hot side of the low-temperature heat regenerator sequentially flows through a multi-stage compression heat pump assembly of a heat supply system to release heat, is mixed with the carbon dioxide working medium at the outlet of the precooler after being cooled and enters a compressor; liquid organic working medium flowing out of an outlet of the condenser is throttled, the temperature and the pressure are reduced and converted into organic working medium of wet steam, the organic working medium enters the multistage compression heat pump assembly, the temperature and the pressure are gradually reduced, the multistage evaporator arranged in the multistage compression heat pump assembly is used for gradually recovering cold end waste heat of the supercritical carbon dioxide power generation system, the organic working medium of the wet steam is converted into gaseous organic working medium, the gaseous organic working medium is gradually compressed and boosted and heated through the multistage compressor arranged in the multistage compression heat pump assembly, and then the gaseous organic working medium enters the condenser for condensation and heat release, so that heat is provided for a heat user.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention provides supercritical CO integrated with a multi-stage compression heat pump2The system can reduce the heat exchange temperature difference between a cold end working medium and a heat pump evaporation working medium, reduce the irreversible loss of heat transfer, and effectively improve the COP of the heat pump, thereby greatly improving the utilization level of the waste heat of the cold end of the system. Meanwhile, the multi-stage compression heat pump is adopted to recover the waste heat of the cold end, so that the irreversible heat transfer loss is greatly reduced, the energy is utilized in a graded and graded manner, and the energy utilization efficiency of the system is greatly improved. In addition, the invention can realize thermoelectric decoupling, thereby greatly improving the operation flexibility of the system.
Drawings
FIG. 1 shows supercritical CO of an integrated multi-stage compression heat pump according to the present invention2A cogeneration system schematic;
FIG. 2 shows the supercritical CO of the two-stage compression heat pump in the embodiment2A cogeneration system schematic;
FIG. 3 is a temperature entropy diagram of a single-stage compression heat pump cycle in an embodiment;
FIG. 4 is a temperature entropy diagram of a two-stage compression heat pump cycle in an embodiment;
in the figure: the system comprises a main compressor 1, a low-temperature regenerator 2, a high-temperature regenerator 3, a boiler 4, a turbine 5, a precooler 6, an auxiliary compressor 7, a flow regulating valve 8, a first-stage evaporator 9, a second-stage evaporator 10, a third-stage evaporator 11, a fourth-stage evaporator 12, a fourth-stage compressor 13, a third-stage compressor 14, a second-stage compressor 15, a first-stage compressor 16, a condenser 17, a first-stage throttle valve 18, a second-stage throttle valve 19, a third-stage throttle valve 20 and a fourth-stage throttle valve 21.
Detailed Description
The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
Supercritical CO integrated with multistage compression heat pump2A cogeneration system, as shown in fig. 1, including a supercritical carbon dioxide cycle power generation system and a heat supply system; comprises a main compressor 1, a low-temperature heat regenerator 2, a high-temperature heat regenerator 3, a boiler 4, a turbine 5, a precooler 6, an auxiliary compressor 7, a flow regulating valve 8, a first-stage evaporator 9, a second-stage evaporator 10, a third-stage evaporator 11, a fourth-stage evaporator 12, a fourth-stage compressor 13, a third-stage compressor 14, a second-stage compressor 15, a first-stage compressor 16, a condenser 17, a first-stage throttle valve 18, a second-stage throttle valve 19, a third-stage throttle valve 20 and a fourth-stage throttle valve 21,
the supercritical carbon dioxide cycle power generation system comprises a main compressor 1, a low-temperature heat regenerator 2, a high-temperature heat regenerator 3, a boiler 4, a turbine 5, a precooler 6 and an auxiliary compressor 7, wherein the outlet of the main compressor 1 is sequentially communicated with the low-temperature heat regenerator 2, the high-temperature heat regenerator 3, the boiler 4 and the turbine 5, and the outlet of the precooler 6 is communicated with the inlet of the main compressor 1; the inlet of the auxiliary compressor 7 is communicated with the hot side outlet of the low-temperature regenerator 2, and the outlet of the auxiliary compressor 7 is communicated with the cold side outlet of the low-temperature regenerator 2;
the heat supply system comprises a multi-stage compression heat pump assembly and a condenser 17, the multi-stage compression heat pump assembly is connected in series step by step, and the hot end of the multi-stage compression heat pump assembly is communicated with the supercritical carbon dioxide cycle power generation system; the cold end of the multi-stage compression heat pump assembly is in communication with a condenser 17.
The multi-stage compression heat pump assembly comprises a multi-stage evaporator and a multi-stage compressor, and the multi-stage compression heat pump assembly at least comprises two evaporators and two compressors. The multistage evaporator comprises N stages of evaporators, including a first stage evaporator 9, a second stage evaporator 10, a third stage evaporator 11, a fourth stage evaporator 12, … …, a Nth stage evaporator, including a first stage evaporator 9, a second stage evaporator 10, a third stage evaporator 11, a fourth stage evaporator 12, … …, the Nth stage evaporator is connected in series in turn, the multistage compressor comprises N stages of compressors, a first stage compressor 16, a second stage compressor 15, a third stage compressor 14, a fourth stage compressor 13, … …, the Nth stage compressor, wherein the first stage compressor 16, the second stage compressor 15, the third stage compressor 14, the fourth stage compressor 13, … …, the Nth stage compressor 13 are connected in series in turn, wherein an outlet of the first stage compressor 16 is communicated with an inlet of the condenser 17, a cold side outlet of the first stage evaporator 9 is communicated with an inlet of the first stage compressor 16, a cold side outlet of the second-stage evaporator 10 is communicated with an inlet of a second-stage compressor 15, a cold side outlet of the third-stage evaporator 11 is communicated with an inlet of a third-stage compressor 14, a cold side outlet of the fourth-stage evaporator 12 is communicated with an inlet of a fourth-stage compressor 13, … … corresponds to the cold side outlet of the Nth-stage evaporator and is communicated with the inlet of the Nth-stage compressor, a hot side outlet of the first-stage evaporator 9 is communicated with a hot side inlet of the second-stage evaporator 10, a hot side outlet of the second-stage evaporator 10 is communicated with a hot side inlet of the third-stage evaporator 11, a hot side outlet of the third-stage evaporator 11 is communicated with a hot side inlet of the fourth-stage evaporator 12, a hot side outlet of the … … Nth-1-stage evaporator is communicated with a hot side inlet of the Nth-stage evaporator, the hot sides of the evaporators are sequentially connected in series, and an inlet of the first-stage evaporator 9 is communicated with a hot side outlet of the low-temperature regenerator 2 of the supercritical carbon dioxide cycle power generation system, and a cold side outlet of the Nth-stage evaporator is communicated with an inlet of the Nth-stage compressor, a cold side inlet of the Nth-stage evaporator is communicated with a cold side outlet of the (N-1) th-stage evaporator, a hot side outlet of the Nth-stage evaporator is communicated with a main compressor 1 of the supercritical carbon dioxide cycle power generation system, wherein N is a positive integer.
In a preferred embodiment of the present invention, a flow control valve 8 is provided between the low-temperature regenerator 2 and the first-stage evaporator 9 to control the flow rate of carbon dioxide in the evaporator, thereby controlling the heat load.
Pressure throttle valves are arranged at cold side inlets of each stage of evaporator, and the pressure throttle valves comprise a first stage throttle valve 18, a second stage throttle valve 19, a third stage throttle valve 20, a fourth stage throttle valve 21 and an … … Nth stage throttle valve, wherein the first stage throttle valve 18 is arranged at the cold side inlet of the first stage evaporator 9, the second stage throttle valve 19 is arranged at the cold side inlet of the second stage evaporator 10, the third stage throttle valve 20 is arranged at the cold side inlet of the third stage evaporator 11, the fourth stage throttle valve 21 is arranged at the cold side inlet of the fourth stage evaporator 12, the Nth stage throttle valve 1 is arranged at the cold side inlet of the … … Nth stage evaporator 10 and used for adjusting the flow and pressure of carbon dioxide flow working media at each stage, hot side working media in the multistage evaporators are supercritical carbon dioxide, and cold side working media in the multistage evaporators are organic working media. The organic working medium is a refrigerant used for reducing the temperature of a cold-side carbon dioxide working medium in the evaporator, and specifically comprises at least one of R410A, R407C and R134 a.
The working pressure in the multistage evaporator is gradually decreased; and the temperature of the recovered cold-end waste heat in the multistage evaporator is gradually decreased.
As a preferred embodiment of the present invention, the first-stage evaporator 9 recovers cold-end waste heat with a higher temperature, and reduces the cold-end waste heat step by step, and the nth-stage evaporator recovers cold-end waste heat with a lower temperature, so as to realize quality-based and step utilization of the cold-end waste heat.
Supercritical CO integrated with multistage compression heat pump2A method of co-generation of heat and power, comprising,
in a non-heating period, after the supercritical carbon dioxide working medium is boosted by the main compressor 1, the supercritical carbon dioxide working medium absorbs heat in the low-temperature regenerator 2, the high-temperature regenerator 3 and the boiler 4 in sequence and then enters the turbine 5 to do work, the carbon dioxide working medium after doing work is released heat in the high-temperature regenerator 3 and the low-temperature regenerator 2 and then is divided into two strands, one strand is cooled by the cooler 6 and then enters the main compressor 1 to form a closed power generation circulating system, and the other strand is compressed by the auxiliary compressor 7 and then converges at an outlet at the cold side of the low-temperature regenerator 2;
in the heating period, part of carbon dioxide working medium shunted at the outlet of the hot side of the low-temperature heat regenerator 2 sequentially flows through a multi-stage compression heat pump assembly of the heating system to release heat, and is mixed with the carbon dioxide working medium at the outlet of the precooler 6 after being cooled and enters the compressor 1; the liquid organic working medium flowing out of the outlet of the condenser 17 is throttled, the temperature and the pressure are reduced and converted into the organic working medium of wet steam, the organic working medium enters the multi-stage compression heat pump assembly and is gradually reduced along with the temperature and the pressure, the multi-stage evaporator arranged in the multi-stage compression heat pump assembly is used for gradually recovering the cold end waste heat of the supercritical carbon dioxide power generation system, the organic working medium of the wet steam is converted into the gaseous organic working medium and is then gradually compressed, boosted and heated through the multi-stage compressor arranged in the multi-stage compression heat pump assembly, and then the organic working medium enters the condenser 17 for condensation and heat release, so that heat is provided for a heat user.
As shown in fig. 2, a preferred embodiment is as follows: the present embodiment preferably comprises a two-stage compression heat pump assembly comprising a first stage evaporator 9 and a second stage evaporator 10, a first stage compressor 16 and a second stage compressor 15, a first stage throttle valve 18 and a second stage throttle valve 19. The first stage evaporator 9 is a high pressure evaporator, the second stage evaporator 10 is a low pressure evaporator, the first stage compressor 16 is a high pressure compressor, the second stage compressor 15 is a low pressure compressor, the first stage throttle valve 18 is a high pressure throttle valve, and the second stage throttle valve 19 is a low pressure throttle valve.
An outlet of a main compressor 1, a cold side inlet and outlet of a low-temperature heat regenerator 2, a cold side inlet and outlet of a high-temperature heat regenerator 3, an inlet and outlet of a boiler 4, an inlet and outlet of a turbine 5, an inlet and outlet of a hot side of the high-temperature heat regenerator 3, an inlet and outlet of a hot side of the low-temperature heat regenerator 2, an inlet and outlet of a precooler 6 and an inlet of the main compressor 1 are sequentially communicated; an inlet and an outlet of the auxiliary compressor 7 are respectively communicated with an outlet of the hot side of the low-temperature heat regenerator 2 and an outlet of the cold side of the low-temperature heat regenerator 2;
the flow control valve 8, the high-pressure evaporator and the low-pressure evaporator of the heating system are sequentially communicated, the inlet of the flow control valve 8 is communicated with the hot side outlet of the low-temperature heat regenerator 2, the hot side outlet of the low-pressure evaporator is communicated with the inlet of the compressor, the high-pressure throttle valve, the high-pressure evaporator, the high-pressure compressor and the condenser 17 are sequentially communicated, the outlet of the high-pressure throttle valve is communicated with the inlet of the low-pressure throttle valve, the low-pressure evaporator and the low-pressure compressor are sequentially communicated, and the outlet of the low-pressure compressor is communicated with the inlet of the high-pressure compressor.
In the embodiment, the working temperature of the low-pressure evaporator is 25-35 ℃, and the working temperature of the high-pressure evaporator is 40-50 ℃.
The organic working medium adopted in the embodiment is R134 a;
the high-pressure evaporator recovers cold end waste heat with high temperature, and the low-pressure evaporator recovers cold end waste heat with low temperature, so that quality-based gradient utilization of the cold end waste heat is realized.
The flow control valve 8 adjusts the heat load by adjusting the flow of carbon dioxide in the high-pressure evaporator and the low-pressure evaporator.
Supercritical CO of multi-stage compression heat pump2The specific implementation process of the cogeneration system is as follows:
in a non-heating period, the flow regulating valve 8 is closed, a supercritical carbon dioxide working medium is boosted by the main compressor 1, then absorbs heat in the low-temperature heat regenerator 2, the high-temperature heat regenerator 3 and the boiler 4 in sequence and then enters the turbine 5 to do work, the exhaust gas of the turbine 5 is released heat in the high-temperature heat regenerator 3 and the low-temperature heat regenerator 2 and then is divided into two strands, one strand is cooled by the cooler 6 and then enters the main compressor 1 to form a closed power generation circulating system, and the other strand is compressed by the auxiliary compressor 7 and then converges to the cold side outlet of the low-temperature heat regenerator 2;
in the heating period, the flow regulating valve 8 is opened, a part of carbon dioxide working medium is shunted at the outlet of the hot side of the low-temperature heat regenerator 2, flows through a high-pressure evaporator and a low-pressure evaporator of the heat pump heating system in sequence and releases heat, and the carbon dioxide working medium is mixed with the carbon dioxide working medium at the outlet of the precooler 6 after being cooled and enters the compressor 1; the heating system has the function of converting low-temperature heat absorption of the high-pressure evaporator and the low-pressure evaporator into high-temperature heat release of the condenser 17 for heating by consuming certain work; the flow regulating valve 8 regulates the heat supply of the heat pump heating system by regulating the flow of carbon dioxide working medium at the hot side of the high-pressure evaporator and the low-pressure evaporator of the heat pump heating system; the working process of the heat pump heating system is that after the liquid working medium at the outlet of the condenser 17 is throttled by the high-pressure throttle valve, the temperature and the pressure are reduced and are converted into wet steam, wherein one part of the wet steam enters the high-pressure evaporator to be used for recovering the waste heat with higher temperature at the cold end of the supercritical carbon dioxide power generation system and is converted into a gaseous state from the wet steam; the other part is throttled again by a low-pressure throttle valve, the temperature and the pressure are further reduced, the humidity is further increased, the other part enters a low-pressure evaporator for recovering waste heat with lower temperature at the cold end, wet steam is converted into a gaseous state, the gaseous state is compressed by a low-pressure compressor, the mixture is mixed with a gaseous working medium at the cold side outlet of the high-pressure evaporator after the pressure and the temperature are increased, the mixture is compressed by the high-pressure compressor, and the mixture enters a condenser 17 for condensation and heat release after the pressure and the temperature are further increased, so that heat is provided for a heat user; the other operation processes of the supercritical carbon dioxide power generation system are the same as the heating period.
The working principle of the compression heat pump is shown in fig. 3, and mainly comprises four processes: compression, condensation heat release, throttling and evaporation heat absorption, and the heat pump converts low-temperature heat into high-temperature heat through compression and supplies heat. As can be seen from fig. 2, increasing the evaporation temperature reduces the compression power consumption, thereby increasing the COP of the heat pump. Therefore, compared with a single-stage heat pump, the heat pump arranged in the two-stage high-pressure and low-pressure evaporator shown in fig. 3 can reduce the heat exchange temperature difference and improve the average evaporation temperature of the heat pump when absorbing the high-temperature and low-temperature waste heat at the cold end, thereby improving the performance of the heat pump and further improving the heat supply capacity of the heat pump.
As shown in fig. 4, the heat pump heating system of the present invention adopts a two-stage evaporator arrangement of a high-pressure evaporator 9 and a low-pressure evaporator 10 for absorbing the waste heat at the cold end. The more the evaporator stages are, the smaller the heat exchange temperature difference between the heat pump working medium in the evaporator and the supercritical carbon dioxide working medium carrying waste heat at the cold end is, the higher the average evaporation temperature of the heat pump is, the higher the COP of the heat pump is and the higher the energy utilization efficiency is; meanwhile, heat pump equipment is increased, the system is more complex, and the cost is increased. Therefore, in the embodiment of the present invention, the number of evaporation stages is not limited to two, but is also applicable to a case where the number of evaporation stages is larger than two, and in practical application, the optimal number of evaporation stages should be selected by comprehensively considering the factors of efficiency and cost.
Claims (10)
1. Supercritical CO integrated with multistage compression heat pump2The cogeneration system is characterized by comprising a supercritical carbon dioxide circulation power generation system and a heat supply system;
the supercritical carbon dioxide cycle power generation system comprises a main compressor (1), a low-temperature heat regenerator (2), a high-temperature heat regenerator (3), a boiler (4), a turbine (5), a precooler (6) and an auxiliary compressor (7), wherein the outlet of the main compressor (1) is sequentially communicated with the low-temperature heat regenerator (2), the high-temperature heat regenerator (3), the boiler (4) and the turbine (5), and the outlet of the precooler (6) is communicated with the inlet of the main compressor (1); an inlet of the auxiliary compressor (7) is communicated with a hot side outlet of the low-temperature regenerator (2), and an outlet of the auxiliary compressor (7) is communicated with a cold side outlet of the low-temperature regenerator (2);
the heat supply system comprises a multi-stage compression heat pump assembly and a condenser (17), the multi-stage compression heat pump assembly is connected in series step by step, and a hot end inlet of the multi-stage compression heat pump assembly is communicated with a hot side outlet of a low-temperature heat regenerator (2) of the supercritical carbon dioxide cycle power generation system; and the hot end outlet of the multi-stage compression heat pump assembly is communicated with a main compressor (1) of the supercritical carbon dioxide cycle power generation system, and the cold end of the multi-stage compression heat pump assembly is communicated with a condenser (17).
2. The supercritical CO of an integrated multi-stage compression heat pump according to claim 12The heat and power cogeneration system is characterized in that the multi-stage compression heat pump assembly comprises N-stage evaporators and N-stage compressors, wherein N is a positive integer and is more than or equal to 2, the adjacent evaporators and the adjacent compressors are connected in series, a cold side outlet of a first-stage evaporator (9) is communicated with an inlet of a first-stage compressor (16), an outlet of the first-stage compressor (16) is communicated with an inlet of a condenser (17), a hot side outlet of the first-stage evaporator (9) is communicated with a hot side inlet of a second-stage evaporator (10), the hot side inlet of the first-stage evaporator (9) is communicated with a cold side outlet of a low-temperature regenerator (2) of the supercritical carbon dioxide cycle power generation system, a cold side outlet of an Nth-stage evaporator is communicated with an inlet of the Nth-stage compressor, and the cold side inlet of the Nth evaporator is communicated with a cold side outlet of the Nth-1-stage evaporator, and the hot side outlet of the Nth stage evaporator is communicated with a main compressor (1) of the supercritical carbon dioxide cycle power generation system.
3. Supercritical CO of an integrated multistage compression heat pump according to claim 22The cogeneration system is characterized in that a flow regulating valve (8) is arranged between the low-temperature heat regenerator (2) and the first-stage evaporator (9).
4. Supercritical CO of an integrated multistage compression heat pump according to claim 22The cogeneration system is characterized in that a pressure throttle valve is arranged at a cold side inlet of each stage of evaporator.
5. The supercritical CO of an integrated multi-stage compression heat pump of claim 22A cogeneration system, wherein said multi-stage compression heat pump assembly comprises at least two evaporators and two compressors.
6. Supercritical CO of an integrated multistage compression heat pump according to claim 22The cogeneration system is characterized in that a working medium at the hot side in the multistage evaporator is carbon dioxide, and a working medium at the cold side in the multistage evaporator is an organic working medium.
7. Supercritical CO of an integrated multistage compression heat pump according to claim 62Cogeneration system, characterized in that, organic working medium includes at least one of R410A, R407C and R134 a.
8. Supercritical CO of an integrated multistage compression heat pump according to claim 22A cogeneration system characterized in that the working pressure in the multistage evaporator is decreased stepwise; and the temperature of the recovered cold-end waste heat in the multistage evaporator is gradually decreased.
9. The supercritical CO of an integrated multi-stage compression heat pump according to claim 12Cogeneration system, characterized in that said condenser (17) supplies heat to a heat consumer.
10. Supercritical CO integrated with multistage compression heat pump2Cogeneration method, characterized in that a Cogeneration system according to any one of claims 1-9, comprises,
in a non-heating period, after the supercritical carbon dioxide working medium is boosted by the main compressor (1), the supercritical carbon dioxide working medium absorbs heat in the low-temperature heat regenerator (2), the high-temperature heat regenerator (3) and the boiler (4) in sequence and then enters the turbine (5) to do work, the carbon dioxide working medium after doing work is released heat in the high-temperature heat regenerator (3) and the low-temperature heat regenerator (2) and then is divided into two strands, one strand is cooled by the cooler (6) and then enters the main compressor (1) to form a closed power generation circulating system, and the other strand is compressed by the auxiliary compressor (7) and then converges to the cold side outlet of the low-temperature heat regenerator (2);
in the heating period, part of carbon dioxide working medium shunted from the outlet of the hot side of the low-temperature heat regenerator (2) sequentially flows through a multi-stage compression heat pump assembly of a heat supply system to release heat, is mixed with the carbon dioxide working medium at the outlet of the precooler (6) after being cooled and enters the compressor (1); liquid organic working medium flowing out of an outlet of the condenser (17) is throttled, the temperature and the pressure are reduced and are converted into wet steam organic working medium, the wet steam organic working medium enters the multi-stage compression heat pump assembly and is gradually reduced along with the temperature and the pressure, cold end waste heat of the supercritical carbon dioxide power generation system is gradually recovered by a multi-stage evaporator arranged in the multi-stage compression heat pump assembly, the wet steam organic working medium is converted into gaseous organic working medium, the gaseous organic working medium is gradually compressed and boosted and heated by a multi-stage compressor arranged in the multi-stage compression heat pump assembly, and then the gaseous organic working medium enters the condenser (17) to be condensed and released, so that heat is provided for a heat user.
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