CO2 combined power circulation device and method based on tower type photo-thermal technology

Abstract

The invention relates to the technical field of new energy, in particular to a CO2 combined power circulation device and method based on a tower type photo-thermal technology. The invention provides a CO2 combined power circulation device based on a tower-type photo-thermal technology aiming at the problem that the solar energy utilization rate is low in the prior art. The tower-type photo-thermal unit, the supercritical CO2 recompression cycle unit, the transcritical CO2 power cycle unit and the steam Rankine cycle unit are sequentially connected in series, the steam Rankine cycle unit is connected with the tower-type photo-thermal unit to form a cycle, the concept and principle of proper distribution, respective places, temperature alignment and gradient utilization are followed, and in addition, the tower-type photo-thermal unit, the supercritical CO2 recompression cycle unit, the transcritical CO2 power cycle unit and the steam Rankine cycle unit are connected in series. And the double-effect absorption refrigeration cycle unit is used for further utilizing dead steam of the steam Rankine cycle unit, so that deep utilization of solar energy is achieved, meanwhile, greenhouse gas emission is reduced, and the whole world is promoted to be transformed into low-carbon economy.

Description

Technical Field

[0001] The present disclosure relates to the field of new energy technology, and in particular to a CO2 combined power cycle device and method based on tower-type solar thermal technology. Background Art

[0002] As a renewable energy source, solar energy has attracted attention for its environmental friendliness, sustainability, and abundant resources. Advances in solar technology have led to a gradual reduction in costs and a widening range of applications, encompassing household, commercial, and industrial uses. At the same time, countries and regions are promoting relevant policies and incentives to promote the development and adoption of solar energy. However, the efficiency of solar thermal energy utilization still needs to be improved. Furthermore, solar thermal energy, a medium-to-high temperature heat source, if efficiently utilized, could significantly contribute to resolving the energy crisis.

[0003] Currently, one approach to addressing this problem is coupling solar energy with other renewable energy sources. CN113074094A discloses a biomass-tower solar power generation system based on an organic Rankine cycle. While this coupled power generation system can reduce overall power generation costs and improve solar energy utilization efficiency to a certain extent, the organic Rankine cycle requires a driving heat source of 100-300°C, which cannot fully utilize the medium- and high-temperature heat sources from sunlight. Consequently, energy utilization remains low.

[0004] In summary, how to provide a device and method that can fully and deeply utilize solar energy has become an urgent problem to be solved. Summary of the Invention

[0005] In order to solve the above technical problems, the present disclosure provides a CO2 combined power cycle device and method based on tower solar thermal technology.

[0006] In a first aspect, the present disclosure provides a CO2 combined power cycle device based on tower-type solar thermal technology, which is arranged in sequence from upstream to downstream:

[0007] Tower-type solar thermal units are used to absorb solar energy and heat the thermal storage medium;

[0008] a supercritical CO2 recompression cycle unit for absorbing heat from the heat storage medium of the tower-type solar thermal unit to generate electricity;

[0009] A transcritical CO2 power cycle unit, configured to generate electricity by absorbing heat from the heat storage medium exchanged through the supercritical CO2 recompression cycle unit;

[0010] A steam Rankine cycle unit, configured to absorb heat from the heat storage medium exchanged through the transcritical CO2 power cycle unit to generate electricity;

[0011] and a double-effect absorption refrigeration cycle unit for utilizing the heat of exhaust steam generated after power generation by the steam Rankine cycle unit for refrigeration; and the generated cooling energy is provided to the supercritical CO2 recompression cycle unit, the transcritical CO2 power cycle unit, and the steam Rankine cycle unit;

[0012] The steam Rankine cycle unit is also connected to the tower-type photothermal unit to enable the heat storage medium to circulate.

[0013] This disclosure addresses the low solar energy utilization rate in existing technologies and proposes a CO2 combined power cycle device based on tower solar thermal technology. This disclosure connects a tower solar thermal unit, a supercritical CO2 recompression cycle unit, a transcritical CO2 power cycle unit, and a steam Rankine cycle unit in series, and connects the steam Rankine cycle unit to the tower solar thermal unit to form a cycle. This adheres to the concept and principle of "proper distribution, each in its proper place, temperature matching, and cascade utilization." Furthermore, a double-effect absorption refrigeration cycle unit is used to further utilize the exhaust steam from the steam Rankine cycle unit, thereby achieving in-depth utilization of solar energy. This, in turn, helps reduce greenhouse gas emissions and promote the global transition to a low-carbon economy.

[0014] In addition, the cold energy generated by the double-effect absorption refrigeration cycle unit is provided to the supercritical CO2 recompression cycle unit, the transcritical CO2 power cycle unit and the steam Rankine cycle unit (such as a cooler, a condenser, etc.) for cooling the corresponding medium, thereby realizing further utilization of energy.

[0015] The following are preferred technical solutions of the present disclosure, but are not intended to limit the technical solutions provided by the present disclosure. Through the following technical solutions, the technical objectives and beneficial effects of the present disclosure can be better achieved and realized.

[0016] As a preferred technical solution of the present disclosure, the tower-type solar thermal unit includes:

[0017] Heliostats, used to focus sunlight onto a heat-absorbing tower;

[0018] a heat absorption tower for heating a heat storage medium using solar energy;

[0019] High-temperature heat storage tank, used to store heated heat storage medium;

[0020] and a low-temperature heat storage tank for storing and recovering the heat storage medium after heat exchange and providing it to the heat absorption tower for use.

[0021] Preferably, a heat absorber is provided on the top of the heat absorption tower, and the heat absorber is used to absorb heat from sunlight to heat the heat storage medium.

[0022] Optionally, the heliostats in the tower solar thermal unit are arranged in a ring-shaped staggered, "unobstructed" and "subdivided area" mirror field with high efficiency and small footprint.

[0023] The high-temperature heat storage tank and low-temperature heat storage tank in the tower-type solar thermal unit can solve the mismatch between solar energy production and demand in time, space and intensity, so that the heat energy stored during the day can also be used at night.

[0024] As a preferred technical solution of the present disclosure, the supercritical CO2 recompression cycle unit includes:

[0025] A heater, configured to absorb heat from the heat storage medium in the high-temperature heat storage tank to heat CO2 to form supercritical CO2;

[0026] a first turbine for generating electricity using supercritical CO2 from the heater to generate exhaust steam;

[0027] a high-temperature regenerator, configured to preheat the low-temperature fluid in the high-temperature regenerator using heat from the exhaust steam of the first turbine;

[0028] a low-temperature regenerator, configured to preheat the low-temperature fluid in the low-temperature regenerator using the heat of the exhaust steam from the high-temperature regenerator;

[0029] a cooler, used to cool down part of the exhaust steam from the low-temperature regenerator;

[0030] a main compressor for compressing the exhaust steam from the cooler and delivering it to the low-temperature regenerator as a low-temperature fluid;

[0031] and, a recompressor for compressing another portion of the exhaust steam from the low-temperature regenerator and delivering it to the high-temperature regenerator as a low-temperature fluid;

[0032] Furthermore, the low-temperature regenerator is also connected to the high-temperature regenerator, so that the low-temperature fluid preheated in the low-temperature regenerator is also transported to the high-temperature regenerator for further preheating;

[0033] Furthermore, the high-temperature regenerator is also connected to the heater, so that the fluid preheated by the high-temperature regenerator returns to the heater, forming a cycle.

[0034] As a preferred technical solution of the present disclosure, the first turbine is independently connected to the main compressor and the re-compressor for providing electricity.

[0035] As a preferred technical solution of the present disclosure, the transcritical CO2 power cycle unit includes:

[0036] The first generator is used to absorb the heat of the heat storage medium after heat exchange by the heater to heat CO2 to form supercritical CO2;

[0037] a second turbine for generating electricity using the supercritical CO2 from the first generator to generate exhaust steam;

[0038] a first regenerator, for cooling exhaust steam from the second turbine;

[0039] a first condenser, configured to condense the exhaust steam from the first regenerator to form liquid CO2;

[0040] and, a first pressure pump, for pressurizing the liquid CO2 from the first condenser and delivering it to the first regenerator to absorb heat from the exhaust steam for preheating;

[0041] In addition, the first regenerator is also connected to the first generator, so that the preheated CO2 in the first regenerator returns to the first generator, forming a cycle.

[0042] As a preferred technical solution of the present disclosure, the steam Rankine cycle unit includes:

[0043] The second generator is used to absorb the heat of the heat storage medium after the heat exchange in the first generator to heat water and form water vapor;

[0044] a third turbine for generating electricity using the steam from the second generator, generating exhaust steam, and driving the double-effect absorption refrigeration cycle unit for refrigeration;

[0045] A first heat exchanger is used to cool the exhaust steam after being utilized by the double-effect absorption refrigeration cycle unit;

[0046] a second condenser, configured to condense the exhaust steam from the first heat exchanger to form water;

[0047] and, a second pressure pump, for pressurizing the water from the second condenser and delivering it to the first heat exchanger to absorb heat from the exhaust steam for preheating;

[0048] In addition, the first heat exchanger is also connected to the second generator, so that the preheated water in the first heat exchanger returns to the second generator to form a cycle.

[0049] As a preferred technical solution of the present disclosure, the double-effect absorption refrigeration cycle unit includes:

[0050] a high-pressure generator for absorbing heat from the exhaust steam of the third turbine to heat the dilute solution, thereby evaporating part of the refrigerant therein to form a vapor-state refrigerant, and converting the dilute solution into a basic solution;

[0051] a high-pressure heat exchanger for precooling the base solution from the high-pressure generator using a cryogenic fluid;

[0052] a first throttle valve for reducing the pressure of the basic solution from the high-pressure heat exchanger;

[0053] a low-pressure generator for heating the basic solution from the first throttle valve so that part of the refrigerant therein evaporates to form vapor-state refrigerant, and the basic solution becomes a concentrated solution;

[0054] a low-pressure heat exchanger for precooling the concentrated solution from the low-pressure generator using a low-temperature fluid;

[0055] a second throttle valve, for reducing the pressure of the concentrated solution from the low-pressure heat exchanger;

[0056] a high-pressure condenser, configured to condense the vapor refrigerant from the high-pressure generator to obtain liquid refrigerant;

[0057] a third throttle valve, for reducing the pressure of the liquid refrigerant from the high-pressure condenser;

[0058] a low-pressure condenser for condensing the liquid refrigerant from the third throttle valve and the vapor refrigerant from the low-pressure generator to form liquid refrigerant;

[0059] a fourth throttle valve, for reducing the pressure of the liquid refrigerant from the low-pressure condenser;

[0060] an evaporator, configured to receive liquid refrigerant from the fourth throttle valve and absorb external heat to evaporate the liquid refrigerant into vapor refrigerant, thereby achieving refrigeration;

[0061] an absorber for receiving the concentrated solution from the second throttle valve and mixing it with the vapor refrigerant from the evaporator to form a weak solution;

[0062] The absorber is also connected to the low-pressure heat exchanger, the high-pressure heat exchanger, and the high-pressure generator in sequence, so that the obtained dilute solution is used as a low-temperature fluid to pre-cool the fluids in the low-pressure heat exchanger and the high-pressure heat exchanger in sequence, and then enters the high-pressure generator to form a cycle.

[0063] The dilute solution and the concentrated solution refer to the relative concentrations of the solutions in the double-effect absorption refrigeration cycle unit, and the concentration of the basic solution is between the dilute solution and the concentrated solution.

[0064] As a preferred technical solution of the present disclosure, the double-effect absorption refrigeration cycle unit is a double-effect lithium bromide absorption refrigeration cycle unit.

[0065] In a second aspect, the present disclosure provides a CO2 combined power cycle method based on tower-type solar thermal technology, which is carried out using the CO2 combined power cycle device based on tower-type solar thermal technology as described in the first aspect;

[0066] The CO2 combined power cycle method based on tower-type solar thermal technology includes:

[0067] Using tower-type solar thermal units to absorb solar energy and heat the heat storage medium;

[0068] In order from upstream to downstream, the heat storage medium heated by the tower-type solar thermal unit is used as a driving heat source to flow through the supercritical CO2 recompression cycle unit, the transcritical CO2 power cycle unit, and the steam Rankine cycle unit in sequence for heat exchange, thereby driving the supercritical CO2 recompression cycle unit, the transcritical CO2 power cycle unit, and the steam Rankine cycle unit to generate electricity, thereby realizing the cascade utilization of solar energy; and the heat storage medium after heat exchange in the steam Rankine cycle unit is also returned to the tower-type solar thermal unit, so that the heat storage medium is circulated;

[0069] At the same time, the double-effect absorption refrigeration cycle unit also uses the exhaust steam generated after the steam Rankine cycle unit generates electricity for refrigeration;

[0070] The temperature of the heat storage medium entering the supercritical CO2 recompression cycle unit is 500-600°C, such as 500°C, 520°C, 540°C, 560°C, 580°C, 590°C or 600°C, and preferably 550-570°C;

[0071] The temperature of the heat storage medium entering the transcritical CO2 power cycle unit is 400-500°C, such as 400°C, 420°C, 440°C, 460°C, 480°C or 500°C, preferably 440-460°C;

[0072] The temperature of the heat storage medium entering the steam Rankine cycle unit is 300-400°C, such as 300°C, 320°C, 340°C, 360°C, 380°C or 400°C, preferably 340-360°C;

[0073] The temperature of the heat storage medium entering the double-effect absorption refrigeration cycle unit is 190-250°C, for example, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C;

[0074] The temperature of the heat storage medium after heat exchange in the steam Rankine cycle unit is 250-320°C, for example, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C or 320°C;

[0075] However, it is not limited to the listed values, and other values not listed within the above range are also applicable.

[0076] The CO2 combined power cycle method based on tower solar thermal technology described in the present disclosure converts solar energy into thermal energy according to the energy utilization concept of "temperature matching and cascade utilization", realizes the cascade utilization of energy from high to low, obtains electricity and cold energy, and greatly improves the energy utilization rate.

[0077] As a preferred technical solution of the present disclosure, the heat storage medium used in the tower-type solar thermal unit includes molten salt.

[0078] As a preferred technical solution of the present disclosure, the molten salt includes 60 wt % of NaNO 3 and 40 wt % of KNO 3 in terms of mass percentage.

[0079] The CO2 in the supercritical CO2 recompression cycle unit and the transcritical CO2 power cycle unit is buffered and stored in high-pressure storage tanks during system operation to balance system pressure fluctuations and ensure cycle stability. The high-pressure storage tanks are made of high-pressure resistant (20-30MPa) and corrosion-resistant (such as stainless steel or nickel-based alloy) materials and are equipped with safety valves, pressure sensors and temperature control systems.

[0080] For long-term or backup storage of CO2, liquid CO2 storage tanks are used. During shutdown or low load, supercritical CO2 and transcritical CO2 are cooled to liquid state (maintaining high pressure and low temperature) and stored in liquid CO2 storage tanks.

[0081] The technical solution provided by the embodiments of the present disclosure has the following advantages over the prior art:

[0082] The present invention connects a tower-type solar thermal unit, a supercritical CO2 recompression cycle unit, a transcritical CO2 power cycle unit and a steam Rankine cycle unit in series in sequence, and connects the steam Rankine cycle unit to the tower-type solar thermal unit to form a cycle, following the concept and principle of "proper distribution, each in its place, temperature matching, and cascade utilization". In addition, a double-effect absorption refrigeration cycle unit is used to further utilize the exhaust steam of the steam Rankine cycle unit, thereby realizing the deep utilization of solar energy. At the same time, it helps to reduce greenhouse gas emissions and promote the global transition to a low-carbon economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0084] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0085] Figure 1 This is a schematic structural diagram of a CO2 combined power cycle device based on tower-type solar thermal technology according to a specific embodiment of the present disclosure;

[0086] Among them, 1. Tower-type solar thermal unit; 1-1. Heliostat; 1-2. Heat absorption tower; 1-3. High-temperature heat storage tank; 1-4. Low-temperature heat storage tank;

[0087] 2. Supercritical CO2 recompression cycle unit; 2-1. Heater; 2-2. First turbine; 2-3. High-temperature regenerator; 2-4. Low-temperature regenerator; 2-5. Cooler; 2-6. Main compressor; 2-7. Recompressor;

[0088] 3. Transcritical CO2 power cycle unit; 3-1. First generator; 3-2. Second turbine; 3-3. First regenerator; 3-4. First condenser; 3-5. First booster pump;

[0089] 4. Steam Rankine cycle unit; 4-1. Second generator; 4-2. Third turbine; 4-3. First heat exchanger; 4-4. Second condenser; 4-5. Second booster pump;

[0090] 5. Double-effect absorption refrigeration cycle unit; 5-1. High-pressure generator; 5-2. High-pressure heat exchanger; 5-3. First throttle valve; 5-4. Low-pressure generator; 5-5. Low-pressure heat exchanger; 5-6. Second throttle valve; 5-7. High-pressure condenser; 5-8. Third throttle valve; 5-9. Low-pressure condenser; 5-10. Fourth throttle valve; 5-11. Evaporator; 5-12. Absorber. DETAILED DESCRIPTION

[0091] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features therein can be combined with each other in the absence of conflict.

[0092] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0093] Example 1

[0094] The embodiment of the present disclosure provides a CO2 combined power cycle device based on tower-type solar thermal technology, the structural diagram of which is shown in FIG. Figure 1 As shown, it includes the following settings from upstream to downstream:

[0095] The tower-type solar thermal unit 1 is used to absorb solar energy and heat the heat storage medium;

[0096] A supercritical CO2 recompression cycle unit 2 is used to absorb heat from the heat storage medium of the tower-type solar thermal unit 1 to generate electricity;

[0097] The transcritical CO2 power cycle unit 3 is used to absorb the heat of the heat storage medium exchanged by the supercritical CO2 recompression cycle unit 2 to generate electricity;

[0098] The steam Rankine cycle unit 4 is used to absorb the heat of the heat storage medium exchanged by the transcritical CO2 power cycle unit 3 to generate electricity;

[0099] and, a double-effect absorption refrigeration cycle unit 5, for utilizing the heat of exhaust steam generated after power generation by the steam Rankine cycle unit 4 for refrigeration; and the generated cooling energy is provided to the supercritical CO2 recompression cycle unit 2, the transcritical CO2 power cycle unit 3, and the steam Rankine cycle unit 4;

[0100] The steam Rankine cycle unit 4 is also connected to the tower-type photothermal unit 1 to enable the heat storage medium to circulate.

[0101] Furthermore, the tower-type solar thermal unit 1 comprises:

[0102] Heliostat 1-1, used to focus sunlight onto heat absorption tower 1-2;

[0103] Heat absorption tower 1-2, used to heat the heat storage medium using solar energy;

[0104] High-temperature heat storage tanks 1-3, used to store heated heat storage medium;

[0105] and, low-temperature heat storage tanks 1-4, for storing and recovering the heat storage medium after heat exchange, and providing it to the heat absorption tower 1-2 for use;

[0106] Furthermore, a heat absorber is provided on the top of the heat absorption tower 1-2, and the heat absorber is used to absorb heat from sunlight to heat the heat storage medium.

[0107] Furthermore, the supercritical CO2 recompression cycle unit 2 includes:

[0108] The heater 2-1 is used to absorb heat from the heat storage medium in the high-temperature heat storage tank 1-3 to heat CO2 to form supercritical CO2;

[0109] a first turbine 2-2 for generating electricity using the supercritical CO2 from the heater 2-1, and generating exhaust steam after the electricity is generated;

[0110] a high-temperature regenerator 2-3, configured to preheat the low-temperature fluid in the high-temperature regenerator 2-3 by utilizing the heat of the exhaust steam from the first turbine 2-2;

[0111] The low-temperature regenerator 2-4 is used to preheat the low-temperature fluid in the low-temperature regenerator 2-4 by using the heat of the exhaust steam from the high-temperature regenerator 2-3;

[0112] Cooler 2-5, used to cool down part of the exhaust steam from the low-temperature regenerator 2-4;

[0113] The main compressor 2-6 is used to compress the exhaust steam from the cooler 2-5 and transport it to the low-temperature regenerator 2-4 as a low-temperature fluid;

[0114] and, a re-compressor 2-7, for compressing another portion of the exhaust steam from the low-temperature regenerator 2-4 and delivering it to the high-temperature regenerator 2-3 as a low-temperature fluid;

[0115] Furthermore, the low-temperature regenerator 2-4 is also connected to the high-temperature regenerator 2-3, so that the low-temperature fluid preheated in the low-temperature regenerator 2-4 is also transported to the high-temperature regenerator 2-3 for further preheating;

[0116] Furthermore, the high-temperature regenerator 2-3 is also connected to the heater 2-1, so that the fluid preheated by the high-temperature regenerator 2-3 returns to the heater 2-1, forming a cycle.

[0117] Furthermore, the first turbine 2-2 is independently connected to the main compressor 2-6 and the re-compressor 2-7 for providing electricity.

[0118] Furthermore, the transcritical CO2 power cycle unit 3 comprises:

[0119] The first generator 3-1 is used to absorb the heat of the heat storage medium after heat exchange in the heater 2-1 to heat CO2 to form supercritical CO2;

[0120] The second turbine 3-2 is used to generate electricity using the supercritical CO2 from the first generator 3-1, and to generate exhaust steam after power generation;

[0121] a first regenerator 3-3 for cooling the exhaust steam from the second turbine 3-2;

[0122] The first condenser 3-4 is used to condense the exhaust steam from the first regenerator 3-3 to form liquid CO2;

[0123] and, a first pressure pump 3-5, for pressurizing the liquid CO2 from the first condenser 3-4 and delivering it to the first regenerator 3-3 to absorb the heat of the exhaust steam for preheating;

[0124] In addition, the first regenerator 3 - 3 is also connected to the first generator 3 - 1 , so that the preheated CO 2 in the first regenerator 3 - 3 returns to the first generator 3 - 1 , forming a cycle.

[0125] Furthermore, the steam Rankine cycle unit 4 includes:

[0126] The second generator 4-1 is used to absorb the heat of the heat storage medium after heat exchange in the first generator 3-1 to heat water and form water vapor;

[0127] The third turbine 4-2 is used to generate electricity using the water vapor from the second generator 4-1, generating exhaust steam, which is used to drive the double-effect absorption refrigeration cycle unit 5 to perform refrigeration;

[0128] The first heat exchanger 4-3 is used to cool the exhaust steam after being utilized by the double-effect absorption refrigeration cycle unit 5;

[0129] The second condenser 4-4 is used to condense the exhaust steam from the first heat exchanger 4-3 to form water;

[0130] and, a second pressure pump 4-5, for pressurizing the water from the second condenser 4-4 and delivering it to the first heat exchanger 4-3 to absorb the heat of the exhaust steam for preheating;

[0131] In addition, the first heat exchanger 4-3 is also connected to the second generator 4-1, so that the preheated water in the first heat exchanger 4-3 returns to the second generator 4-1, forming a cycle.

[0132] Furthermore, the double-effect absorption refrigeration cycle unit 5 comprises:

[0133] The high-pressure generator 5-1 is used to absorb the heat of the exhaust steam from the third turbine 4-2 to heat the dilute solution, so that part of the refrigerant therein evaporates to form vapor refrigerant, and the dilute solution becomes a basic solution;

[0134] a high-pressure heat exchanger 5-2, for precooling the basic solution from the high-pressure generator 5-1 using a low-temperature fluid;

[0135] a first throttle valve 5 - 3 , for reducing the pressure of the basic solution from the high-pressure heat exchanger 5 - 2 ;

[0136] The low-pressure generator 5-4 is used to heat the basic solution from the first throttle valve 5-3, so that part of the refrigerant therein evaporates to form vapor refrigerant, and the basic solution becomes a concentrated solution;

[0137] a low-pressure heat exchanger 5-5 for precooling the concentrated solution from the low-pressure generator 5-4 using a low-temperature fluid;

[0138] a second throttle valve 5 - 6 , for reducing the pressure of the concentrated solution from the low-pressure heat exchanger 5 - 5 ;

[0139] a high-pressure condenser 5-7, configured to condense the vapor refrigerant from the high-pressure generator 5-1 to obtain liquid refrigerant;

[0140] a third throttle valve 5-8, for reducing the pressure of the liquid refrigerant from the high-pressure condenser 5-7;

[0141] a low-pressure condenser 5-9, configured to condense the liquid refrigerant from the third throttle valve 5-8 and the vapor refrigerant from the low-pressure generator 5-4 to form liquid refrigerant;

[0142] a fourth throttle valve 5-10, for reducing the pressure of the liquid refrigerant from the low-pressure condenser 5-9;

[0143] The evaporator 5-11 is used to receive the liquid refrigerant from the fourth throttle valve 5-10 and absorb external heat to evaporate the liquid refrigerant into a vapor refrigerant to achieve refrigeration;

[0144] an absorber 5-12, configured to receive the concentrated solution from the second throttle valve 5-6 and mix it with the vapor refrigerant from the evaporator 5-11 to form a dilute solution;

[0145] The absorber 5-12 is also connected to the low-pressure heat exchanger 5-5, the high-pressure heat exchanger 5-2, and the high-pressure generator 5-1 in sequence, so that the obtained dilute solution is used as a low-temperature fluid to pre-cool the fluids in the low-pressure heat exchanger 5-5 and the high-pressure heat exchanger 5-2 in sequence, and then enters the high-pressure generator 5-1 to form a cycle.

[0146] Furthermore, the double-effect absorption refrigeration cycle unit 5 is a double-effect lithium bromide absorption refrigeration cycle unit.

[0147] Example 2

[0148] The present disclosure also provides a CO2 combined power cycle method based on tower-type solar thermal technology, which is carried out using the CO2 combined power cycle device based on tower-type solar thermal technology described in Example 1;

[0149] The CO2 combined power cycle method based on tower-type solar thermal technology includes:

[0150] The tower-type photothermal unit 1 absorbs solar energy to heat the heat storage medium;

[0151] In order from upstream to downstream, the heat storage medium heated by the tower-type solar thermal unit 1 is used as a driving heat source to flow through the supercritical CO2 recompression cycle unit 2, the transcritical CO2 power cycle unit 3, and the steam Rankine cycle unit 4 in sequence for heat exchange, thereby driving the supercritical CO2 recompression cycle unit 2, the transcritical CO2 power cycle unit 3, and the steam Rankine cycle unit 4 to generate electricity, thereby realizing the cascade utilization of solar energy; and the heat storage medium after heat exchange in the steam Rankine cycle unit 4 is also returned to the tower-type solar thermal unit 1, so that the heat storage medium is circulated;

[0152] At the same time, the double-effect absorption refrigeration cycle unit 5 also uses the exhaust steam generated after the steam Rankine cycle unit 4 generates electricity for refrigeration; and the generated cold energy is provided to the supercritical CO2 recompression cycle unit 2, the transcritical CO2 power cycle unit 3 and the steam Rankine cycle unit 4;

[0153] The temperature of the heat storage medium entering the supercritical CO2 recompression cycle unit 2 is 565°C;

[0154] The temperature of the heat storage medium entering the transcritical CO2 power cycle unit 3 is 450°C;

[0155] The temperature of the heat storage medium entering the steam Rankine cycle unit 4 is 350°C;

[0156] The temperature of the exhaust steam entering the double-effect absorption refrigeration cycle unit 5 is 200°C;

[0157] The temperature of the heat storage medium after heat exchange in the steam Rankine cycle unit 4 is 290°C.

[0158] Furthermore, the heat storage medium used in the tower-type solar thermal unit 1 is a binary molten salt, which comprises 60 wt % of NaNO 3 and 40 wt % of KNO 3 in terms of mass percentage.

[0159] The disclosed embodiment connects a tower-type solar thermal unit, a supercritical CO2 recompression cycle unit, a transcritical CO2 power cycle unit, and a steam Rankine cycle unit in series in sequence, and connects the steam Rankine cycle unit to the tower-type solar thermal unit to form a cycle, following the concept and principle of "proper distribution, each in its place, temperature matching, and cascade utilization". In addition, a double-effect absorption refrigeration cycle unit is used to further utilize the exhaust steam of the steam Rankine cycle unit, thereby achieving in-depth utilization of solar energy. At the same time, it helps to reduce greenhouse gas emissions and promote the global transition to a low-carbon economy.

[0160] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0161] The foregoing description is intended only to provide specific embodiments of the present disclosure, intended to enable those skilled in the art to understand and implement the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments described herein, but rather to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A CO2 combined power cycle device based on tower-type solar thermal technology, characterized in that: Including the following settings from upstream to downstream: Tower-type solar thermal units are used to absorb solar energy and heat the thermal storage medium; a supercritical CO2 recompression cycle unit for absorbing heat from the heat storage medium of the tower-type solar thermal unit to generate electricity; A transcritical CO2 power cycle unit, configured to generate electricity by absorbing heat from the heat storage medium exchanged through the supercritical CO2 recompression cycle unit; A steam Rankine cycle unit, configured to absorb heat from the heat storage medium exchanged through the transcritical CO2 power cycle unit to generate electricity; and a double-effect absorption refrigeration cycle unit for utilizing the heat of exhaust steam generated after power generation by the steam Rankine cycle unit for refrigeration; and the generated cooling energy is provided to the supercritical CO2 recompression cycle unit, the transcritical CO2 power cycle unit, and the steam Rankine cycle unit; The steam Rankine cycle unit is also connected to the tower-type photothermal unit to enable the heat storage medium to circulate.

2. The CO2 combined power cycle device based on tower-type solar thermal technology according to claim 1 is characterized in that: The double-effect absorption refrigeration cycle unit is a double-effect lithium bromide absorption refrigeration cycle unit.

3. A CO2 combined power cycle method based on tower solar thermal technology, characterized in that: The method is carried out by using a CO2 combined power cycle device based on tower-type solar thermal technology as described in claim 1 or 2; The CO2 combined power cycle method based on tower-type solar thermal technology includes: Using tower-type solar thermal units to absorb solar energy and heat the heat storage medium; In order from upstream to downstream, the heat storage medium heated by the tower-type solar thermal unit is used as a driving heat source to flow through the supercritical CO2 recompression cycle unit, the transcritical CO2 power cycle unit, and the steam Rankine cycle unit in sequence for heat exchange, thereby driving the supercritical CO2 recompression cycle unit, the transcritical CO2 power cycle unit, and the steam Rankine cycle unit to generate electricity, thereby realizing the cascade utilization of solar energy; and the heat storage medium after heat exchange in the steam Rankine cycle unit is also returned to the tower-type solar thermal unit, so that the heat storage medium is circulated; At the same time, the double-effect absorption refrigeration cycle unit also uses the exhaust steam generated after the steam Rankine cycle unit generates electricity for refrigeration; Wherein, the temperature of the heat storage medium entering the supercritical CO2 recompression cycle unit is 500-600°C; The temperature of the heat storage medium entering the transcritical CO2 power cycle unit is 400-500°C; The temperature of the heat storage medium entering the steam Rankine cycle unit is 300-400°C; The temperature of the exhaust steam entering the double-effect absorption refrigeration cycle unit is 190-250°C; The temperature of the heat storage medium after heat exchange in the steam Rankine cycle unit is 250-320°C.

4. The CO2 combined power cycle method based on tower solar thermal technology according to claim 3 is characterized in that: The heat storage medium used in the tower-type solar thermal unit includes molten salt.

5. The CO2 combined power cycle method based on tower solar thermal technology according to claim 4, characterized in that: In terms of mass percentage, the molten salt includes 60 wt % of NaNO 3 and 40 wt % of KNO 3 .

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