CN115930476A

CN115930476A - Power generation and refrigeration combined system based on supercritical carbon dioxide

Info

Publication number: CN115930476A
Application number: CN202310037384.3A
Authority: CN
Inventors: 张峰; 谌冰洁; 杨晨旭; 周竣斌; 游明烨
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2023-01-10
Filing date: 2023-01-10
Publication date: 2023-04-07

Abstract

The invention discloses a power generation and refrigeration combined system based on supercritical carbon dioxide, which relates to the technical field of power generation and refrigeration and comprises the following components: the system comprises a heater, a turbine, an air inlet regulating valve, a high-temperature supercritical carbon dioxide storage device, an air outlet regulating valve, a high-temperature heat regenerator, a low-temperature heat regenerator, a cooler, a flow dividing three-way valve, a main compressor, a secondary compressor, a confluence three-way valve, a refrigeration compressor, an intermediate heat exchanger, a throttle valve and an evaporator, wherein the supercritical carbon dioxide power generation cycle and the transcritical carbon dioxide refrigeration cycle are highly integrated; and the main compressor, the recompressor and the generator are all driven by mechanical energy output by the turbine. The system can fully utilize the waste heat of refrigeration compression, effectively improve the energy conversion efficiency, and flexibly switch to a refrigeration, power generation and combined cooling and power mode.

Description

Power generation and refrigeration combined system based on supercritical carbon dioxide

Technical Field

The invention relates to the technical field of power generation and refrigeration, in particular to a power generation and refrigeration combined system based on supercritical carbon dioxide.

Background

The energy consumption of China is increased year by year from 43 hundred million tons of standard coal in 2015 to 2021, the energy consumption is increased to 52.3 hundred million tons of standard coal, and the energy consumption is increased by 21 percentage points in comparison with the energy consumption in 2015. To date, china has become the first major energy consuming country in the world, the second major greenhouse gas emitting country, energy crisis and global warming have made China face huge energy conservation and emission reduction and carbon emission pressure, and for this reason, china has proposed 2030 year carbon peak reaching goal and 2060 year carbon neutralization goal. The proportion of electric energy to the consumption of industrial terminal energy is about 30%, and the proportion of electric energy to be consumed by cooling is increased year by year, so that the high-efficiency, flexible and adjustable combined cooling and power system is widely concerned.

The supercritical carbon dioxide Brayton cycle is based on Brayton cycle and takes carbon dioxide in a supercritical state as power cycle of a working medium, and by utilizing the high density and heat transfer performance of the power cycle and special physical properties near a critical zone, the power consumption of a compressor can be greatly reduced, the cycle thermal efficiency can be improved, and the Brayton cycle is one of the most potential thermal power generation cycle modes in the future. In addition, carbon dioxide is used as a natural working medium, has zero ODP value, negligible GWP value, good stability, low price, rich natural reserve, high density, large specific heat and volumetric refrigerating capacity, high latent heat and thermal conductivity and no recovery problem, is a natural refrigerant, and a refrigerating system based on carbon dioxide is also considered to be one of the most ideal refrigerating modes.

In summary, how to integrate the supercritical carbon dioxide power generation cycle and the carbon dioxide-based refrigeration cycle to make the combined cooling and power system compact and efficient, and flexible and adjustable according to the external load change is a problem to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, the invention aims to provide a power generation and refrigeration combined system based on supercritical carbon dioxide, which can fully utilize waste heat of refrigeration compression, effectively improve energy conversion efficiency, flexibly switch refrigeration, power generation and combined cooling and power supply modes, and flexibly adjust power generation amount and refrigeration amount according to actual load requirements, thereby meeting different refrigeration temperature requirements.

In order to achieve the above purpose, the invention provides the following technical scheme:

a power generation and refrigeration combined system based on supercritical carbon dioxide comprises: the system comprises a heater, a turbine, a high-temperature regenerator, a low-temperature regenerator, a cooler, a main compressor, a recompressor, a refrigeration compressor, a throttle valve and an evaporator, wherein the heater, the turbine, the high-temperature regenerator, the low-temperature regenerator, the cooler, the main compressor, the recompressor, the low-temperature regenerator, the high-temperature regenerator and the heater are sequentially connected to form a supercritical carbon dioxide power generation cycle, and the refrigeration compressor, the cooler, the throttle valve, the evaporator and the refrigeration compressor are sequentially connected to form a transcritical carbon dioxide refrigeration cycle;

the inlet of the turbine is connected with the outlet of the heater; the hot side inlet of the high-temperature heat regenerator is connected with the outlet of the turbine; the hot side inlet of the low-temperature regenerator is connected with the hot side outlet of the high-temperature regenerator; the hot side inlet of the cooler is connected with the hot side outlet of the low-temperature heat regenerator, and the inlet of the re-compressor is connected with the outlet of the refrigeration compressor; the inlet of the main compressor and the inlet of the throttle valve are both connected with the hot side outlet of the cooler; the outlet of the throttling valve is connected with the hot side inlet of the evaporator; the hot side outlet of the evaporator is connected with the inlet of the refrigeration compressor; the outlet of the main compressor is connected with the cold side inlet of the low-temperature regenerator; the outlet of the recompressor and the cold side outlet of the low-temperature regenerator are both connected with the cold side inlet of the high-temperature regenerator; a cold side outlet of the high-temperature regenerator is connected with an inlet of the heater;

the main compressor, the secondary compressor and the generator are driven by mechanical energy output by the turbine, the generator generates electric energy to supply power to users, the refrigeration compressor is driven by the mechanical energy output by the turbine, and the evaporator is used for cooling fluid supplied to cold energy users.

Preferably, the heat pump system further comprises an intermediate heat regenerator, the outlet of the hot side of the cooler and the inlet of the main compressor are both connected with the inlet of the hot side of the intermediate heat regenerator, the outlet of the hot side of the intermediate heat regenerator is connected with the inlet of the throttle valve, the inlet of the cold side of the intermediate heat regenerator is connected with the cold side outlet of the evaporator, and the outlet of the cold side of the intermediate heat regenerator is connected with the inlet of the refrigeration compressor.

Preferably, the system further comprises a shunt three-way valve, the shunt three-way valve is used for controlling the flow of the carbon dioxide flowing to the intermediate heat regenerator and the main compressor, an inlet of the shunt three-way valve is connected with a hot side outlet of the cooler, and an inlet of the main compressor and a hot side inlet of the intermediate heat regenerator are respectively connected with two outlets of the shunt three-way valve.

Preferably, the system further comprises a confluence three-way valve, wherein the confluence three-way valve is used for controlling the flow of carbon dioxide flowing from a hot side outlet of the low-temperature regenerator to the recompressor, an outlet of the refrigeration compressor, the hot side outlet of the low-temperature regenerator and a hot side inlet of the cooler are connected with an inlet of the confluence three-way valve, and an outlet of the confluence three-way valve is connected with an inlet of the recompressor.

Preferably, the system further comprises a high-temperature supercritical carbon dioxide storage device, control valves are arranged at an inlet and an outlet of the high-temperature supercritical carbon dioxide storage device, a cold-side outlet of the high-temperature heat regenerator and an inlet of the heater are connected with an inlet of the high-temperature supercritical carbon dioxide storage device, and an outlet of the turbine and a hot-side inlet of the high-temperature heat regenerator are connected with an outlet of the high-temperature supercritical carbon dioxide storage device.

Preferably, the turbine, the generator, the main compressor, the secondary compressor and the refrigeration compressor are coaxially connected through a speed regulation clutch device, so that the rotating speed of each impeller machine is adjustable.

Preferably, the heat source absorbed by the heater comprises a nuclear reactor of a nuclear power plant, or a boiler of a coal-fired power plant, or a heat collector of a solar power plant, or a geothermal source of a geothermal power plant, or a gas turbine tail gas of a gas turbine power generation system, or industrial waste heat.

When the supercritical carbon dioxide power generation and refrigeration-based combined system provided by the invention is used, a supercritical carbon dioxide power generation cycle and a transcritical carbon dioxide refrigeration cycle are highly integrated, the supercritical carbon dioxide power generation cycle comprises a heater, a turbine, a high-temperature heat regenerator, a low-temperature heat regenerator, a cooler, a main compressor and a re-compressor, and a circulating working medium is carbon dioxide. The transcritical carbon dioxide refrigeration cycle comprises a refrigeration compressor, a cooler, an intermediate heat regenerator, a throttle valve and an evaporator, wherein the refrigeration working medium is carbon dioxide; a cooler is shared by the supercritical carbon dioxide power generation cycle and the transcritical carbon dioxide refrigeration cycle; the compressed working medium of the transcritical carbon dioxide refrigeration cycle is converged into the working medium to participate in the power generation cycle, and the waste heat of the refrigeration and compression is utilized.

And the transcritical carbon dioxide refrigeration cycle is driven by the supercritical carbon dioxide power generation cycle, extra high-grade electric energy is not consumed, the mechanical rotating speed of each impeller is adjustable, and the refrigeration compressor can be disconnected with the turbine in a complete power generation mode. The working medium of the refrigeration cycle is carbon dioxide, the temperature of liquid carbon dioxide can be reduced to be below 0 ℃, and the evaporation temperature of the carbon dioxide can be changed by adjusting the pressure drop of the throttle valve, so that different refrigeration requirements such as air conditioner cooling, food preservation, refrigeration and the like can be met.

In conclusion, the supercritical carbon dioxide-based power generation and refrigeration combined system provided by the invention can fully utilize the waste heat of refrigeration compression, effectively improve the energy conversion efficiency, flexibly switch the refrigeration, power generation and combined cooling and power supply modes, flexibly adjust the generated energy and the refrigerating capacity according to the actual load demand, and meet different refrigeration temperature demands.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a power generation and refrigeration combined system based on supercritical carbon dioxide provided by the invention.

In fig. 1:

the system comprises a generator 1, a turbine 2, a heater 3, a high-temperature regenerator 4, a low-temperature regenerator 5, a cooler 6, a cold energy user 7, an evaporator 8, a throttle valve 9, an intermediate regenerator 10, a refrigeration compressor 11, a main compressor 12, a secondary compressor 13, an electric energy user 14, a shunt three-way valve 15, a confluence three-way valve 16 and a high-temperature supercritical carbon dioxide storage device 17.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The core of the invention is to provide a power generation and refrigeration combined system based on supercritical carbon dioxide, which can fully utilize the waste heat of refrigeration compression, effectively improve the energy conversion efficiency, flexibly switch the refrigeration, power generation and combined cooling and power supply modes, flexibly adjust the generated energy and the refrigeration quantity according to the actual load requirement, and meet the requirements of different refrigeration temperatures.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a power generation and refrigeration combination system based on supercritical carbon dioxide according to the present invention.

This embodiment provides a refrigeration combined system based on supercritical carbon dioxide electricity generation, includes: the system comprises a heater 3, a turbine 2, a high-temperature heat regenerator 4, a low-temperature heat regenerator 5, a cooler 6, a main compressor 12, a recompressor 13, a refrigeration compressor 11, a throttle valve 9 and an evaporator 8, wherein the heater 3, the turbine 2, the high-temperature heat regenerator 4, the low-temperature heat regenerator 5, the cooler 6, the main compressor 12, the recompressor 13, the low-temperature heat regenerator 5, the high-temperature heat regenerator 4 and the heater 3 are sequentially connected to form a supercritical carbon dioxide power generation cycle, and the refrigeration compressor 11, the cooler 6, the throttle valve 9, the evaporator 8 and the refrigeration compressor 11 are sequentially connected to form a transcritical carbon dioxide refrigeration cycle;

the inlet of the turbine 2 is connected with the outlet of the heater 3; the hot side inlet of the high-temperature regenerator 4 is connected with the outlet of the turbine 2; the hot side inlet of the low-temperature regenerator 5 is connected with the hot side outlet of the high-temperature regenerator 4; the hot side inlet of the cooler 6 is connected with the hot side outlet of the low-temperature heat regenerator 5, and the inlet of the recompressor 13 is connected with the outlet of the refrigeration compressor 11; the inlet of the main compressor 12 and the inlet of the throttle valve 9 are both connected with the hot side outlet of the cooler 6; the outlet of the throttle valve 9 is connected with the hot-side inlet of the evaporator 8; the hot side outlet of the evaporator 8 is connected to the inlet of a refrigeration compressor 11; the outlet of the main compressor 12 is connected to the cold side inlet of the low temperature regenerator 5; the outlet of the recompressor 13 and the cold side outlet of the low-temperature regenerator 5 are both connected with the cold side inlet of the high-temperature regenerator 4; the cold side outlet of the high temperature regenerator 4 is connected to the inlet of the heater 3.

The main compressor 12, the recompressor 13 and the generator 1 are all driven by mechanical energy output by the turbine 2, the generator 1 generates electric energy to be supplied to an electric energy user 14, the refrigeration compressor 11 is driven by mechanical energy output by the turbine 2, and the evaporator 8 is used for cooling fluid supplied to a cold energy user 7.

It should be noted that, the carbon dioxide in the heater 3 absorbs the heat of the heat source and then is heated, the high-temperature and high-pressure air flow enters the turbine 2 and expands in the turbine 2 to do work, the heat energy of the supercritical carbon dioxide is converted into mechanical energy of the rotating turbine 2, the mechanical energy is used for driving the main compressor 12, the recompressor 13 and the refrigeration compressor 11 to compress the carbon dioxide and driving the coaxially connected generator 1 to generate electricity, and the electricity generated by the generator 1 is supplied to the electricity consumer 14; the carbon dioxide expanded by the turbine 2 flows through the high-temperature regenerator 4 and the low-temperature regenerator 5 in sequence and releases heat to preheat the compressed carbon dioxide.

The carbon dioxide after the heat is released by the two heat regenerators is divided into two parts: one part directly enters a re-compressor 13 for compression; another portion enters cooler 6 where it further releases heat and is cooled to near the critical point temperature. The carbon dioxide cooled by the cooler 6 is divided into two parts: a part of the carbon dioxide gas flow enters a main compressor 12 for pressurization, the power consumption is reduced due to the fact that the temperature is cooled to be close to the critical point of the carbon dioxide, and then the carbon dioxide gas flow enters a low-temperature heat regenerator 5 for recovering the heat of exhaust gas of the turbine 2; the other part of carbon dioxide flows to a throttle valve 9, throttling, cooling and depressurizing are carried out in the throttle valve 9, so that the temperature of the carbon dioxide is reduced to the evaporation temperature, then the carbon dioxide enters an evaporator 8 to absorb heat and evaporate the carbon dioxide into gas, the evaporation latent heat of the liquid carbon dioxide is utilized for refrigeration, the fluid on the other side of the evaporator 8 is cooled and then supplied to a user needing cold energy, the temperature of the liquid carbon dioxide can be reduced to be below 0 ℃, and the pressure reduction is carried out by adjusting the throttle valve 9, so that the evaporation temperature of the carbon dioxide is changed to meet different refrigeration requirements, such as food preservation, refrigeration, air conditioning cooling and the like; the carbon dioxide after evaporation and heat absorption enters a refrigeration compressor 11 for pressurization; the pressurized carbon dioxide and part of the gas flow at the outlet of the hot side of the low-temperature heat regenerator 5 are mixed and then enter a re-compressor 13 for pressurization, and the residual heat of refrigeration and compression is fully utilized; the carbon dioxide compressed by the recompressor 13 is converged into the outlet airflow at the cold side of the low-temperature heat regenerator 5, and then flows through the high-temperature heat regenerator 4 to further recover the heat of the exhaust gas of the high-temperature turbine 2, so that the temperature is further increased; finally, the carbon dioxide gas flow returns to the heater 3 to complete a complete power generation and refrigeration combined cycle based on the supercritical carbon dioxide.

It should be further noted that the supercritical carbon dioxide power generation and refrigeration combined system highly integrates a supercritical carbon dioxide power generation cycle and a transcritical carbon dioxide refrigeration cycle, the supercritical carbon dioxide power generation cycle includes a heater 3, a turbine 2, a generator 1, a high-temperature heat regenerator 4, a low-temperature heat regenerator 5, a cooler 6, a main compressor 12 and a recompressor 13, and the circulating working medium is carbon dioxide. The transcritical carbon dioxide refrigeration cycle comprises a refrigeration compressor 11, a cooler 6, a throttle valve 9 and an evaporator 8, and the refrigeration working medium is carbon dioxide. And the supercritical carbon dioxide power generation cycle and the transcritical carbon dioxide refrigeration cycle share the cooler 6, and the compressed working medium of the refrigeration subsystem is converged into the recompression working medium of the power generation subsystem to participate in the split-flow recompression process of the power generation subsystem.

Through the arrangement, the supercritical carbon dioxide power generation and refrigeration combined system is compact in structure; meanwhile, the supercritical carbon dioxide power generation subsystem can fully utilize the waste heat of refrigeration compression, and the cold source loss of the refrigeration subsystem is reduced; and the compressed working medium of the refrigeration subsystem participates in the split-flow recompression process of the power generation subsystem, so that the temperature mismatching phenomenon of hot side and cold side fluids in the heat regenerator can be reduced, the irreversible loss in the heat regenerator is reduced, and the cycle efficiency is improved.

In addition, the refrigeration subsystem ring is driven by the power generation subsystem, extra high-grade electric energy is not consumed, the working medium of the refrigeration cycle is carbon dioxide, the temperature of the liquid carbon dioxide can be reduced to be below 0 ℃, and different refrigeration requirements such as air conditioner cold supply, food preservation, refrigeration and the like can be met by changing the evaporation temperature of the carbon dioxide by adjusting the pressure drop of the throttle valve 9. Therefore, the power generation and refrigeration combined system based on the supercritical carbon dioxide can fully recycle the waste heat of refrigeration compression, effectively improve the energy conversion efficiency and meet different refrigeration temperature requirements.

On the basis of the above embodiment, it is preferable that an intermediate regenerator 10 is further included, a hot side outlet of the cooler 6 and an inlet of the primary compressor 12 are both connected to a hot side inlet of the intermediate regenerator 10, a hot side outlet of the intermediate regenerator 10 is connected to an inlet of the throttle valve 9, a cold side inlet of the intermediate regenerator 10 is connected to a cold side outlet of the evaporator 8, and a cold side outlet of the intermediate regenerator 10 is connected to an inlet of the refrigeration compressor 11.

It should be noted that, the intermediate heat regenerator 10 may be disposed between the hot side outlet of the cooler 6 and the inlet of the throttle valve 9, and the carbon dioxide is further cooled in the intermediate heat regenerator 10 after being cooled by the cooler 6, so as to reduce the irreversible loss of the carbon dioxide during the throttling, cooling and pressure reducing processes of the throttle valve 9, improve the efficiency of the refrigeration cycle, and further improve the cycle efficiency of the system.

Preferably, the system further comprises a three-way shunt valve 15, the three-way shunt valve 15 is used for controlling the flow of carbon dioxide flowing to the intermediate regenerator 10 and the main compressor 12, an inlet of the three-way shunt valve 15 is connected to a hot side outlet of the cooler 6, and an inlet of the main compressor 12 and a hot side inlet of the intermediate regenerator 10 are respectively connected to two outlets of the three-way shunt valve 15.

It should be noted that the three-way shunt valve 15 can control the flow of carbon dioxide flowing to the intermediate regenerator 10 and the main compressor 12, that is, the flow of carbon dioxide flowing to the refrigeration subsystem can be controlled, so as to adjust the refrigeration capacity according to the external load, and in addition, the refrigeration subsystem can be turned off, and the mode can be switched to the complete power generation mode, the combined cooling and power mode, and the complete refrigeration mode.

Preferably, the system further comprises a confluence three-way valve 16, wherein the confluence three-way valve 16 is used for controlling the flow of carbon dioxide flowing from a hot-side outlet of the low-temperature regenerator 5 to the recompressor 13, an outlet of the refrigeration compressor 11, a hot-side outlet of the low-temperature regenerator 5 and a hot-side inlet of the cooler 6 are connected with an inlet of the confluence three-way valve 16, and an outlet of the confluence three-way valve 16 is connected with an inlet of the recompressor 13.

It should be added that the confluence three-way valve 16 can control the flow rate of the carbon dioxide flowing from the hot-side outlet of the low-temperature regenerator 5 to the recompressor 13, and also can adjust the split ratio of the power generation subsystem according to the change of the external load, so as to reduce the mismatch phenomenon of the fluid temperatures at the two sides in the regenerator, so as to reduce the irreversible loss in the regenerator and maintain the high efficiency of the system. Meanwhile, the confluence three-way valve 16 and the shunt three-way valve 15 can cooperatively control the flow of the refrigeration subsystem, adjust the refrigeration capacity according to the external refrigeration load demand, and flexibly switch to a complete power generation mode, a combined cooling and power supply mode and a complete refrigeration mode according to the actual demand.

Preferably, the system further comprises a high-temperature supercritical carbon dioxide storage device 17, control valves are arranged at an inlet and an outlet of the high-temperature supercritical carbon dioxide storage device 17, a cold-side outlet of the high-temperature regenerator 4 and an inlet of the heater 3 are connected with an inlet of the high-temperature supercritical carbon dioxide storage device 17, and an outlet of the turbine 2 and a hot-side inlet of the high-temperature regenerator 4 are connected with an outlet of the high-temperature supercritical carbon dioxide storage device 17.

It should be noted that the high-temperature supercritical carbon dioxide storage device 17 can adjust the mass flow of carbon dioxide of the whole system under the action of pressure difference through the control valves of the inlet and outlet under the action of pressure difference, that is, when the external load requirement is reduced, the control valve at the inlet of the high-temperature supercritical carbon dioxide storage device 17 is opened under the control of the electric control device, and the carbon dioxide at the outlet of the hot side of the high-temperature regenerator 4 enters the high-temperature supercritical carbon dioxide storage device 17 under the action of pressure difference, so that the flow of carbon dioxide in the cycle is reduced, and the power generation amount and the refrigerating capacity of the cycle are reduced; when the external load demand is increased, the control valve at the outlet of the high-temperature supercritical carbon dioxide storage device 17 is opened under the control of the electric control device, and the carbon dioxide flows out of the high-temperature supercritical carbon dioxide storage device 17 under the action of the pressure difference and is merged into the exhaust gas of the turbine 2, so that the flow rate of the carbon dioxide in the circulation is increased, and the power generation capacity and the refrigerating capacity of the circulation are increased. Therefore, the system can adjust the power generation amount and the refrigerating capacity according to the external load change so as to meet different power generation and refrigerating load requirements.

Preferably, the turbine 2, the generator 1, the main compressor 13, the recompressor 12 and the refrigeration compressor 11 are coaxially connected through a speed-regulating clutch device, so that the rotating speed of each impeller mechanism can be adjusted. Through the arrangement, the structural compactness of the system can be effectively improved, the rotating speed of each impeller machine is adjustable, and the refrigeration compressor 11 can be disconnected in a complete power generation mode.

Of course, the coaxial connection of the turbine 2, the generator 1, the main compressor 12, the recompressor 13 and the refrigeration compressor 11 is only a preferred embodiment, and is not the only embodiment, that is, the transmission device may be used to connect the turbine 2, the generator 1, the main compressor 12, the recompressor 13 and the refrigeration compressor 11 non-coaxially.

Preferably, the heat source absorbed by the heater 3 comprises a nuclear reactor of a nuclear power plant, or a boiler of a coal-fired power plant, or a heat collector of a solar power plant, or a geothermal source of a geothermal power plant, or a gas turbine tail gas of a gas turbine power generation system, or industrial waste heat. The system is suitable for various heat sources, and has good application prospect.

In order to further illustrate the supercritical carbon dioxide based power generation and refrigeration combination system provided by the present invention, the following description will be made with reference to the above features.

The supercritical carbon dioxide power generation and refrigeration-based combined system provided by the embodiment of the invention highly integrates a supercritical carbon dioxide power generation cycle and a transcritical carbon dioxide refrigeration cycle. The supercritical carbon dioxide power generation cycle comprises a heater 3, a turbine 2, a high-temperature supercritical carbon dioxide storage device 17, a generator 1, a high-temperature heat regenerator 4, a low-temperature heat regenerator 5, a confluence three-way valve 16, a cooler 6, a shunt three-way valve 15, a main compressor 12 and a re-compressor 13, wherein a cycle working medium is carbon dioxide.

The transcritical carbon dioxide refrigeration cycle comprises a refrigeration compressor 11, a confluence three-way valve 16, a cooler 6, a shunt three-way valve 15, an intermediate heat regenerator 10, a throttle valve 9 and an evaporator 8, wherein the refrigeration working medium is carbon dioxide. The supercritical carbon dioxide power generation cycle absorbs high-temperature heat through the heater 3; the transcritical carbon dioxide refrigeration cycle and the supercritical carbon dioxide power generation cycle share the cooler 6, and are integrated through the shunt three-way valve 15 and the confluence three-way valve 16, a compressed working medium of the transcritical carbon dioxide refrigeration cycle is converged into a working medium to participate in the power generation cycle, and the waste heat of refrigeration compression is utilized.

In addition, the refrigeration subsystem is driven by the power generation subsystem, extra high-grade electric energy is not required to be consumed, the working medium of the refrigeration cycle is carbon dioxide, the temperature of the liquid carbon dioxide can be reduced to be below 0 ℃, and different refrigeration requirements such as air conditioner cold supply, food preservation, refrigeration and the like can be met by changing the evaporation temperature of the carbon dioxide by adjusting the pressure drop of the throttle valve 9; the flow dividing three-way valve 15 and the confluence three-way valve 16 can control the flow of carbon dioxide flowing to the refrigeration subsystem according to the external load demand, adjust the refrigerating capacity, and flexibly switch to a complete power generation mode, a combined cooling and power supply mode and a complete refrigeration mode according to the actual demand, and meanwhile, the flow dividing ratio of the power generation subsystem can be adjusted, the irreversible loss in the heat regenerator is reduced, and the high efficiency of the system is kept; in addition, the high-temperature supercritical carbon dioxide storage device 17 can adjust the mass flow of carbon dioxide of the whole system according to the change of external load under the action of pressure difference through the control valves of the inlet and the outlet, thereby meeting different power generation and refrigeration load requirements. Therefore, the system can make full use of the waste heat of refrigeration compression, effectively improve the energy conversion efficiency, flexibly switch the refrigeration, power generation and combined cooling and power supply modes, and flexibly adjust the generated energy and the refrigeration capacity according to the actual load demand so as to meet different refrigeration temperature demands.

The specific implementation scheme of the invention is as follows: the heat carrier transfers heat to the supercritical carbon dioxide circulating working medium in the heater 3, so that the temperature of the supercritical carbon dioxide circulating working medium is raised to the highest circulating temperature, the heated carbon dioxide enters the turbine 2 and expands in the turbine 2 to do work, the heat energy of the supercritical carbon dioxide is converted into mechanical energy for driving the main compressor 12, the recompressor 13 and the refrigeration compressor 11 to compress carbon dioxide flow, and meanwhile, the generator 1 is driven to generate electricity to provide electric energy for an electric energy user 14; the carbon dioxide expanded by the turbine 2 flows through the high-temperature regenerator 4 and the low-temperature regenerator 5 in sequence, and releases heat therein for preheating the compressed carbon dioxide; the carbon dioxide after heat release is divided into two air flows, wherein one air flow flows to the confluence three-way valve 16, and the other air flow flows through the cooler 6 to be cooled to the temperature near the critical point; the cooled carbon dioxide gas flow is divided into two gas flows again through the flow dividing three-way valve 15, one gas flow enters the main compressor 12 for pressurization, the power consumption of the main compressor 12 is reduced due to the fact that the temperature is cooled to be close to the critical point of the carbon dioxide, and the obtained high-pressure gas flow absorbs the heat of exhaust gas of the turbine 2 through the low-temperature heat regenerator 5; meanwhile, another carbon dioxide gas flow branched by the three-way flow divider valve 15 flows to the intermediate regenerator 10 and is further cooled to a liquid state therein; the cooled carbon dioxide is throttled, cooled and depressurized through a throttle valve 9, so that the temperature of the carbon dioxide is further reduced to an evaporation temperature; then enters the evaporator 8 and absorbs heat therein to be evaporated into gas, so that the evaporation latent heat of the liquid carbon dioxide is utilized for refrigeration, and the fluid on the other side of the evaporator 8 is cooled and then is supplied to a user needing cold energy; the evaporated carbon dioxide flows into the other side of the intermediate heat exchanger 10 to absorb heat, and then enters the refrigeration compressor 11 to be pressurized; the pressurized carbon dioxide enters the confluence three-way valve 16 to be converged with the other carbon dioxide gas flow entering the confluence three-way valve 16, and then enters the recompressor 13 for further pressurization; then the air flow is converged with the cold side outlet air flow of the low-temperature heat regenerator 5 and then flows to the high-temperature heat regenerator 4 to further absorb the heat of the exhaust air 2; finally, the airflow returns to the heater 3 to form a complete power generation and refrigeration combined system based on the supercritical carbon dioxide.

In addition, when the external load changes, the control valves at the inlet and outlet of the flow-dividing three-way valve 15, the flow-converging three-way valve 16 and the high-temperature supercritical carbon dioxide storage device 17 can be adjusted to adjust the refrigerating capacity and the generating capacity or switch different power generation and refrigeration modes. For example, when refrigeration is not needed, the valves of the shunt three-way valve 15 and the confluence three-way valve 16 communicated with the refrigeration side can be closed, so that carbon dioxide does not flow to the refrigeration subsystem, and meanwhile, the refrigeration compressor is disconnected from the generator set, and at this time, the system does not provide cold energy any more and is in a complete power generation mode; when power supply is not needed, the valve communicated with the power generation side of the confluence three-way valve 16 can be closed, and the valve communicated with the power generation side of the diversion three-way valve 15 is closed to be small or even closed, so that most or all air flows flow to the refrigeration subsystem, all output work of the turbine 2 is used for driving the compressor, and at the moment, the system does not provide electric energy any more and is in a complete refrigeration mode; when cold energy and electric energy are needed simultaneously, the shunt three-way valve 15 and the confluence three-way valve 16 can be adjusted according to the change of the external refrigeration load requirement, so that the flow of carbon dioxide flowing to the refrigeration subsystem is controlled, and the flexible regulation and control of the refrigeration capacity are realized.

Further, in a complete power generation mode, a complete refrigeration mode or a combined cooling and power mode, when the external overall load demand is reduced, a control valve at the inlet of the high-temperature supercritical carbon dioxide storage device 17 can be opened, so that the circulating working medium flows into the high-temperature supercritical carbon dioxide storage device 17 under the action of pressure difference, the flow of the circulating working medium is reduced, and the mechanical rotating speed of the impeller is adjusted to reduce the provided refrigerating capacity or generating capacity; when the external overall load demand is increased, the control valve at the outlet of the high-temperature supercritical carbon dioxide storage device 17 can be opened, so that carbon dioxide in the high-temperature supercritical carbon dioxide storage device 17 flows out of the high-temperature supercritical carbon dioxide storage device 17 under the action of pressure difference and is converged with the circulating working medium, the flow of the circulating working medium is increased, and the mechanical rotating speed of the impeller is adjusted, so that the provided refrigerating capacity or generated energy is increased.

In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. Any combination of all embodiments provided by the present invention is within the scope of the present invention, and will not be described herein.

The power generation and refrigeration combined system based on the supercritical carbon dioxide provided by the invention is described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. A power generation and refrigeration combined system based on supercritical carbon dioxide is characterized by comprising: the system comprises a heater (3), a turbine (2), a high-temperature regenerator (4), a low-temperature regenerator (5), a cooler (6), a main compressor (12), a recompressor (13), a refrigeration compressor (11), a throttle valve (9) and an evaporator (8), wherein the heater (3), the turbine (2), the high-temperature regenerator (4), the low-temperature regenerator (5), the cooler (6), the main compressor (12), the recompressor (13), the low-temperature regenerator (5), the high-temperature regenerator (4) and the heater (3) are sequentially connected to form a supercritical carbon dioxide power generation cycle, and the refrigeration compressor (11), the cooler (6), the throttle valve (9), the evaporator (8) and the refrigeration compressor (11) are sequentially connected to form a transcritical carbon dioxide refrigeration cycle;

the inlet of the turbine (2) is connected with the outlet of the heater (3); the hot side inlet of the high-temperature regenerator (4) is connected with the outlet of the turbine (2); a hot side inlet of the low-temperature regenerator (5) is connected with a hot side outlet of the high-temperature regenerator (4); the hot side inlet of the cooler (6) is connected with the hot side outlet of the low-temperature heat regenerator (5), and the inlet of the recompressor (13) is connected with the outlet of the refrigeration compressor (11); the inlet of the main compressor (12) and the inlet of the throttling valve (9) are connected with the hot-side outlet of the cooler (6); the outlet of the throttle valve (9) is connected with the hot side inlet of the evaporator (8); the outlet of the hot side of the evaporator (8) is connected with the inlet of the refrigeration compressor (11); the outlet of the main compressor (12) is connected with the cold side inlet of the low-temperature regenerator (5); the outlet of the recompressor (13) and the cold side outlet of the low-temperature regenerator (5) are both connected with the cold side inlet of the high-temperature regenerator (4); the cold side outlet of the high-temperature regenerator (4) is connected with the inlet of the heater (3);

the main compressor (12), the secondary compressor (13) and the generator (1) are driven by mechanical energy output by the turbine (2), the generator (1) generates electric energy to supply to an electric energy user (14), the refrigeration compressor (11) is driven by the mechanical energy output by the turbine (2), and the evaporator (8) is used for cooling fluid supplied to a cold energy user (7).

2. The power generation and refrigeration combination system based on supercritical carbon dioxide according to claim 1, characterized by further comprising an intermediate regenerator (10), wherein the hot side outlet of the cooler (6) and the inlet of the primary compressor (12) are both connected to the hot side inlet of the intermediate regenerator (10), the hot side outlet of the intermediate regenerator (10) is connected to the inlet of the throttle valve (9), the cold side inlet of the intermediate regenerator (10) is connected to the cold side outlet of the evaporator (8), and the cold side outlet of the intermediate regenerator (10) is connected to the inlet of the refrigeration compressor (11).

3. The supercritical carbon dioxide based power generation and refrigeration combined system according to claim 1 further comprises a three-way flow diversion valve (15), wherein the three-way flow diversion valve (15) is used for controlling the flow of carbon dioxide flowing to the intermediate regenerator (10) and the main compressor (12), the inlet of the three-way flow diversion valve (15) is connected with the hot side outlet of the cooler (6), and the inlet of the main compressor (12) and the hot side inlet of the intermediate regenerator (10) are respectively connected with two outlets of the three-way flow diversion valve (15).

4. The supercritical carbon dioxide based power generation and refrigeration combination system according to claim 1, further comprising a confluence three-way valve (16), wherein the confluence three-way valve (16) is used for controlling the flow of carbon dioxide flowing from the hot side outlet of the low temperature regenerator (5) to the recompressor (13), the outlet of the refrigeration compressor (11), the hot side outlet of the low temperature regenerator (5) and the hot side inlet of the cooler (6) are connected with the inlet of the confluence three-way valve (16), and the outlet of the confluence three-way valve (16) is connected with the inlet of the recompressor (13).

5. The power generation and refrigeration combination system based on supercritical carbon dioxide as claimed in claim 1 further comprises a high temperature supercritical carbon dioxide storage device (17), wherein the inlet and outlet of the high temperature supercritical carbon dioxide storage device (17) are provided with control valves, the cold side outlet of the high temperature regenerator (4) and the inlet of the heater (3) are connected with the inlet of the high temperature supercritical carbon dioxide storage device (17), and the outlet of the turbine (2) and the hot side inlet of the high temperature regenerator (4) are connected with the outlet of the high temperature supercritical carbon dioxide storage device (17).

6. The supercritical carbon dioxide based power generation and refrigeration combined system according to any one of claims 1 to 5, characterized in that the turbine (2), the generator (1), the main compressor (13), the recompressor (12) and the refrigeration compressor (11) are coaxially connected through a speed regulation clutch device, so that the rotation speed of each impeller machine can be adjusted.

7. The supercritical carbon dioxide based power generation and refrigeration combined system according to any one of claims 1 to 5, characterized in that the heat source absorbed by the heater (3) comprises nuclear reactor of nuclear power plant, or boiler of coal-fired power plant, or heat collector of solar power plant, or geothermal source of geothermal power plant, or gas turbine exhaust of gas turbine power generation system, or industrial waste heat.