LNG cold energy comprehensive utilization system and method for combined carbon capture and dry ice production in thermal power plants

Abstract

The present invention relates to the field of LNG energy cascade utilization, and discloses a LNG cold energy comprehensive utilization system and method for carbon capture and dry ice production in thermal power plants. A low-temperature carbon capture module, a medium-temperature cold energy storage module, a high-temperature carbon capture module, and a cooling tower are sequentially added after the LNG source. The low-temperature carbon capture module and the high-temperature carbon capture module are used for graded carbon capture. The two-stage carbon capture modules adopt different carbon capture principles and adapt to different temperature ranges, resulting in a good carbon capture effect. When the thermal power plant cannot absorb all the cold energy during peak gas consumption, the medium-temperature cold energy storage module can be provided to store the cold energy. When the gas consumption is low, the cold energy stored in the cold energy storage device can be used to continue carbon capture, which is beneficial to the stable and efficient operation of the system. The present invention realizes the carbon capture process of the flue gas of the thermal power plant through the two-stage carbon capture module, and at the same time, cooperates with the cold energy storage technology and the cooling tower to realize the full and efficient utilization of the LNG cold energy.

Description

Technical Field

[0001] The present invention relates to the field of LNG energy cascade utilization, and in particular to a system and method for comprehensive utilization of LNG cold energy for combined carbon capture and dry ice production in thermal power plants. Background Art

[0002] As my country begins to vigorously promote and develop clean energy and accelerate the construction of a clean, low-carbon, safe and efficient energy system, natural gas, as a readily available fossil energy source, has the advantages of being low-carbon, safe and reliable, with high calorific value per unit and low emissions.

[0003] Liquefied natural gas (LNG), also known as liquefied natural gas, is a cryogenic liquid mixture formed by freezing natural gas to approximately -162°C. Before use, LNG must be vaporized, releasing a significant amount of high-quality cold energy. Traditional processes generally have low LNG cold energy recovery and utilization rates, and this energy utilization is also low. Currently, most thermal power plants in my country are coal-fired, which results in significant carbon dioxide emissions. Furthermore, cooling towers are commonly used as cold-end equipment in power plants. Their operation consumes significant amounts of air cooling energy, and their performance directly impacts the economic efficiency, safety, and stability of power plant operations. Given the large volume of LNG used and the significant amount of cold energy released, the production scale and characteristics of thermal power plants are well-suited to the LNG vaporization process. Therefore, there is a need to explore new technologies and systems to integrate the LNG vaporization process with thermal power plant operations to improve energy utilization and production efficiency.

[0004] The invention patent, application number 202410684188.X, entitled "A Combined Heat and Power System with an Integrated Cascaded Heat Storage and Release System and Its Operation Method," specifically includes a high-temperature heat storage tank, a medium-temperature heat storage tank, a low-temperature heat storage tank, an electric heat pump, a coal-fired boiler, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a steam turbine, a condenser, and a generator. By coupling three heat storage tanks to a conventional cogeneration unit, the electric heat pump and the boiler's main steam combine to absorb excess electricity, heating the working fluid in the heat storage tanks to different temperature levels and storing them. The working fluid at different temperature levels can heat the main steam to increase the unit's peak capacity or heat water in the heating network for heating users. However, this patent only improves the load regulation capability of the cogeneration unit and cannot be applied to reduce CO2 emissions and improve the operating efficiency of thermal power plants by using the large amount of cold energy released during the LNG gasification process. It also cannot achieve the carbon capture of flue gas generated by boiler operation in thermal power plants using the cold energy of LNG.

[0005] The patent number is 202310563543.3, and its name is a multifunctional system for energy storage, carbon capture and air conditioning for LNG cold energy utilization. It is divided according to the order of LNG supply, and includes an LNG supply unit, a carbon capture unit, a compressed carbon dioxide energy storage and release unit, a Kalina cycle power generation unit and an air conditioning unit. The LNG supply unit is connected with the carbon capture unit, the carbon dioxide energy storage and release unit, the Kalina cycle power generation unit and the air conditioning unit in sequence, and a first-stage heat exchanger, a second-stage heat exchanger, a third-stage heat exchanger and a fourth-stage heat exchanger are respectively provided on the LNG supply unit. Through the combined use of the carbon capture system, the carbon dioxide energy storage system, the Kalina cycle power generation system and the air conditioning system, the cascade utilization of LNG cold energy is realized, and the waste of LNG cold energy is reduced. However, the capture effect is defective, and there is no energy storage unit. During the low-peak period of LNG gas consumption, the carbon capture effect cannot be guaranteed. Summary of the Invention

[0006] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a system and method for comprehensive utilization of LNG cold energy for carbon capture and dry ice production in thermal power plants, so as to solve the technical problem of how to utilize the large amount of cold energy released during the LNG gasification process to reduce carbon dioxide emissions from thermal power plants and improve the operating efficiency of thermal power plants.

[0007] The present invention is achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides an LNG cold energy comprehensive utilization system for carbon capture and dry ice production in a thermal power plant, comprising an LNG source, a low-temperature carbon capture module, a medium-temperature cold energy storage module, a high-temperature carbon capture module, a cooling tower, and a seawater heat exchanger;

[0009] The output end of the LNG source is connected to the input end of the low-temperature carbon capture module, the output end of the low-temperature carbon capture module is connected to the input end of the medium-temperature cold energy storage module, the output end of the medium-temperature cold energy storage module is connected to the input end of the high-temperature carbon capture module, and the output end of the high-temperature carbon capture module is connected to the input end of the cooling tower. An LNG pipeline temperature sensor is provided at the output end of the cooling tower, and the output end of the cooling tower is branched after the LNG pipeline temperature sensor, one of which is connected to the user pipeline network; the other branch is connected to the user pipeline network through a seawater heat exchanger.

[0010] Preferably, the low temperature carbon capture module comprises a first low temperature heat exchanger, an expander, a second low temperature compressor and a second low temperature heat exchanger;

[0011] The low-temperature side inlet of the first low-temperature heat exchanger is connected to the output end of the LNG source, and the low-temperature side outlet of the first low-temperature heat exchanger is connected to the medium-temperature cold energy storage module;

[0012] The inlet of the second low-temperature compressor is connected to the flue gas of the thermal power plant; the outlet of the second low-temperature compressor is connected to the high-temperature side inlet of the second low-temperature heat exchanger, and the high-temperature side outlet of the second low-temperature heat exchanger is connected to the high-temperature side inlet of the first low-temperature heat exchanger;

[0013] The high temperature side outlet of the first low temperature heat exchanger is connected to the low temperature side inlet of the second low temperature heat exchanger, the low temperature side outlet of the second low temperature heat exchanger is connected to the inlet of the expander, and the outlet of the expander is connected to the high temperature carbon capture module.

[0014] Furthermore, the cryogenic carbon capture module further comprises a first cryogenic compressor, a cryogenic carbon dioxide storage tank, a dry ice collection device, and a dry ice storage device;

[0015] The input end of the dry ice collection device is connected to the output end of the first low-temperature heat exchanger, the output end of the dry ice collection device is connected to the input end of the dry ice storage device, and the gas outlet of the dry ice storage device is connected to the inlet of the first low-temperature compressor; the outlet of the first low-temperature compressor is connected to the low-temperature carbon dioxide storage tank; the dry ice storage device is connected to the medium-temperature cold energy storage module via a circulation loop, wherein the outer surface of the circulation loop is covered with insulation material and a heat exchange component is provided inside.

[0016] Furthermore, the medium-temperature cold energy storage module includes a medium-temperature heat exchanger and a cold energy storage device;

[0017] The low-temperature side inlet of the medium-temperature heat exchanger is connected to the low-temperature side outlet of the first low-temperature heat exchanger; the low-temperature side outlet of the medium-temperature heat exchanger is connected to the high-temperature carbon capture module;

[0018] The high-temperature side inlet of the medium-temperature heat exchanger is connected to the output end of the cold energy storage device, and the high-temperature side outlet of the medium-temperature heat exchanger is connected to the input end of the cold energy storage device, forming a circulation loop; wherein the outer surface of the circulation loop is covered with a thermal insulation material, and a heat exchange component is provided inside;

[0019] The cold energy storage device is connected to the dry ice storage device through a circulation loop.

[0020] Furthermore, the high-temperature carbon capture module includes a high-temperature heat exchanger, a carbon dioxide absorption device, a carbon dioxide release device, a high-temperature carbon dioxide storage tank, and a high-temperature compressor;

[0021] The low-temperature side inlet of the high-temperature heat exchanger is connected to the low-temperature side outlet of the medium-temperature heat exchanger; the low-temperature side outlet of the high-temperature heat exchanger is connected to the inlet of the cooling tower;

[0022] The gas inlet of the carbon dioxide absorption device is connected to the outlet of the expander; the gas outlet of the carbon dioxide absorption device is connected to the flue gas treatment device or discharged;

[0023] The liquid inlet of the carbon dioxide absorption device is connected to the high-temperature side outlet of the high-temperature heat exchanger, the liquid outlet of the carbon dioxide absorption device is connected to the liquid inlet of the carbon dioxide release device, the gas outlet of the carbon dioxide release device is connected to the inlet of the high-temperature compressor, and the outlet of the high-temperature compressor is connected to the high-temperature carbon dioxide storage tank; the liquid outlet of the carbon dioxide release device is connected to the high-temperature side inlet of the high-temperature heat exchanger.

[0024] Furthermore, the pipeline between the liquid inlet of the carbon dioxide absorption device and the high temperature side outlet of the high temperature heat exchanger is connected to the bypass of the cold energy storage device. The outer surface of the bypass is wrapped with insulation material and a heat exchange component is provided inside.

[0025] Furthermore, a spray device is provided at the liquid inlet end of the carbon dioxide absorption device, for making the carbon dioxide absorption liquid fall evenly in the carbon dioxide absorption device in the form of droplets.

[0026] Furthermore, the pipeline between the outlet of the high-temperature compressor and the high-temperature carbon dioxide storage tank passes through the carbon dioxide release device, wherein a heat exchange component is provided inside the pipeline for heating the rich liquid after absorbing carbon dioxide to ensure complete release of carbon dioxide; the outer surface of the pipeline between the outlet of the high-temperature compressor and the high-temperature carbon dioxide storage tank is covered with insulation material and a high-temperature temperature sensor is provided near the outlet of the high-temperature compressor for monitoring the temperature of the high-pressure carbon dioxide flow in the pipeline; an electric heating device is provided on the inner wall of the pipeline near the high-temperature temperature sensor.

[0027] In a second aspect, the present invention further provides a method for comprehensively utilizing LNG cold energy for combined carbon capture and dry ice production in a thermal power plant. The method is based on the aforementioned system for comprehensively utilizing LNG cold energy for combined carbon capture and dry ice production in a thermal power plant, and includes the following steps:

[0028] The LNG from the output end of the LNG source enters the low-temperature carbon capture module and exchanges heat in the first low-temperature heat exchanger. The flue gas generated by the thermal power plant first passes through the second low-temperature compressor for pressurization and the second low-temperature heat exchanger for preliminary cooling, and then enters the first low-temperature heat exchanger for further cooling. At this time, the flue gas in the first low-temperature heat exchanger undergoes two-stage cooling. A large amount of carbon dioxide in the flue gas is directly condensed into dry ice and falls into the dry ice collection device, and then transported to the dry ice storage device. The remaining flue gas enters the expander for decompression and cooling;

[0029] After heat exchange, the LNG enters the medium-temperature heat exchanger in the medium-temperature cold energy storage module for heat exchange. When the scale of LNG is large, multiple cold energy storage devices can be set up with parallel pipelines, and appropriate cold storage materials can be arranged inside them. The working fluid flow direction of the medium-temperature heat exchanger is set to countercurrent. The dry ice storage device is connected to the cold energy storage device through a circulation loop loaded with appropriate refrigerant. When the dry ice production exceeds the demand, this circulation loop can be activated to exchange heat between the dry ice and the cold storage material in the cold energy storage device. After heat exchange, the dry ice sublimates into carbon dioxide, which is sent to the first low-temperature compressor through a pipeline for pressurization and then enters the low-temperature carbon dioxide storage tank for sealing.

[0030] The flue gas after being decompressed and cooled by the expander in the low-temperature carbon capture module enters the carbon dioxide absorption device of the high-temperature carbon capture module. The liquid inlet of the carbon dioxide absorption device is sprayed with absorption liquid using a properly arranged spray device. After contacting the absorption liquid, the remaining carbon dioxide in the flue gas is absorbed to form a rich liquid, and the remaining flue gas is discharged from the gas outlet of the carbon dioxide absorption device to the atmosphere or other flue gas treatment device; the rich liquid in the carbon dioxide absorption device enters the carbon dioxide release device, where it is heated by a heat exchange component and the absorption liquid releases carbon dioxide to form a lean liquid; the released carbon dioxide is pressurized and heated by a high-temperature compressor, and the temperature of the carbon dioxide in the pipeline is monitored by a high-temperature temperature sensor. When the temperature of the carbon dioxide in the pipeline is too low to heat the rich liquid and completely release the carbon dioxide, the carbon dioxide in the pipeline is heated by an electric heating device; the pressurized and heated carbon dioxide passes through the interior of the carbon dioxide release device, where a heat exchange component is provided to heat the rich liquid after absorbing carbon dioxide. The lean liquid flowing out of the carbon dioxide release device enters the high-temperature side of the high-temperature heat exchanger, is cooled, and then passes into the spray device in the carbon dioxide absorption device again to absorb carbon dioxide, thereby realizing the recycling of the absorption liquid;

[0031] There is a circulation loop connected to the cold energy storage device in the pipeline between the high-temperature side outlet of the high-temperature heat exchanger and the spray device in the carbon dioxide absorption device. When the amount of LNG is small, the amount of LNG reaching the high-temperature carbon capture module is small and the temperature is high, which may not be enough to cool the absorption liquid. At this time, this bypass is activated to use the cold energy of the cold storage material in the cold energy storage device to cool the absorption liquid, ensuring the absorption liquid works well.

[0032] The low-temperature side outlet of the high-temperature heat exchanger is connected to the cooling pipeline in the cooling tower. When the fourth-level utilization of LNG cold energy is completed in the cooling tower, the cooling tower pipeline is arranged in the water collection tank below the cooling tower. The water in the cooling tower is cooled by air during the falling process and falls into the water collection tank. It is then cooled for the second time by the LNG cooling pipeline in the water collection tank. The water temperature at this time is relatively low, and a greater vacuum degree will be generated after entering the condenser, which helps to increase the effective enthalpy drop of the turbine and thus improve the operating efficiency of the thermal power unit; the LNG pipeline in the cooling tower water collection tank is connected to a temperature sensor. When the natural gas temperature at this time meets the user's usage conditions, it is directly sent to the user pipeline network. If the temperature is still low, it enters the seawater heat exchanger for further heating before being sent to the user pipeline network.

[0033] Preferably, the operating temperature range of the low-temperature carbon capture module is approximately -162°C to -100°C; the operating temperature range of the medium-temperature cold energy storage module is approximately -100°C to -20°C; the operating temperature range of the high-temperature carbon capture module is approximately -20°C to 0°C; and the temperature range of natural gas in the cooling tower is approximately 0°C to 10°C.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] The present invention provides a comprehensive LNG cold energy utilization system for carbon capture and dry ice production in a thermal power plant. A low-temperature carbon capture module, a medium-temperature cold energy storage module, a high-temperature carbon capture module, and a cooling tower are sequentially installed after the LNG source. The low-temperature and high-temperature carbon capture modules perform graded carbon capture. The two-stage carbon capture modules utilize different carbon capture principles and adapt to different temperature ranges, resulting in a good carbon capture effect. When the thermal power plant is unable to absorb all the cold energy during peak gas consumption, the medium-temperature cold energy storage module can be installed to store the cold energy. During low gas consumption periods, the cold energy stored in the cold energy storage device can be used to continue carbon capture, which is beneficial to the stable and efficient operation of the system. The present invention utilizes a two-stage carbon capture module to achieve carbon capture of the flue gas from the thermal power plant. At the same time, the cold energy storage technology and the cooling tower are used to fully and efficiently utilize the cold energy of the LNG.

[0036] Furthermore, the low-temperature side inlet of the first low-temperature heat exchanger in the low-temperature carbon capture module is connected to the output end of the LNG source, the low-temperature side outlet of the first low-temperature heat exchanger is connected to the medium-temperature cold energy storage module, and the high-temperature side inlet of the second low-temperature heat exchanger is connected to the flue gas inlet of the thermal power plant; the inlet of the second low-temperature compressor is connected to the flue gas of the thermal power plant; the outlet of the second low-temperature compressor is connected to the high-temperature side inlet of the second low-temperature heat exchanger, and the high-temperature side outlet of the second low-temperature heat exchanger is connected to the high-temperature side inlet of the first low-temperature heat exchanger; the high-temperature side outlet of the first low-temperature heat exchanger is connected to the low-temperature side inlet of the second low-temperature heat exchanger, the low-temperature side outlet of the second low-temperature heat exchanger is connected to the expander inlet, and the expander outlet is connected to the high-temperature carbon capture module, which effectively ensures the carbon capture of the LNG coming out of the LNG source and improves the carbon capture capacity.

[0037] Furthermore, the input end of the dry ice collection device in the low-temperature carbon capture module is connected to the output end of the first low-temperature heat exchanger, the output end of the dry ice collection device is connected to the input end of the dry ice storage device, and the gas outlet of the dry ice storage device is connected to the inlet of the first low-temperature compressor; the outlet of the first low-temperature compressor is connected to the low-temperature carbon dioxide storage tank; the dry ice storage device is connected to the medium-temperature cold energy storage module through a circulation loop, wherein the outer surface of the circulation loop is covered with insulation material and a heat exchange component is provided inside. The large amount of dry ice collected by the dry ice storage device can be used for artificial rainmaking, low-temperature freezing and other aspects to continue to realize the utilization of cold energy.

[0038] Furthermore, the low-temperature side inlet of the medium-temperature heat exchanger in the medium-temperature cold energy storage module is connected to the low-temperature side outlet of the first low-temperature heat exchanger; the low-temperature side outlet of the medium-temperature heat exchanger is connected to the high-temperature carbon capture module; the low-temperature side inlet of the medium-temperature heat exchanger is connected to the low-temperature side outlet of the first low-temperature heat exchanger; the low-temperature side outlet of the medium-temperature heat exchanger is connected to the high-temperature carbon capture module; the high-temperature side inlet of the medium-temperature heat exchanger is connected to the output end of the cold energy storage device, and the high-temperature side outlet of the medium-temperature heat exchanger is connected to the input end of the cold energy storage device, forming a circulation loop; the outer surface of the circulation loop is covered with insulation material, and a heat exchange component is provided inside. During the peak period of gas consumption, LNG cold energy and dry ice cold energy that cannot be consumed by the system are stored, and the stored cold energy is used to continue carbon capture during the low period of gas consumption, thereby ensuring the continuity and stability of the system operation.

[0039] Furthermore, the low-temperature side inlet of the high-temperature heat exchanger in the high-temperature carbon capture module is connected to the low-temperature side outlet of the medium-temperature heat exchanger; the low-temperature side outlet of the high-temperature heat exchanger is connected to the inlet of the cooling tower, and the gas inlet of the carbon dioxide absorption device is connected to the outlet of the expander; the gas outlet of the carbon dioxide absorption device is connected to the flue gas treatment device or discharged, the liquid inlet of the carbon dioxide absorption device is connected to the high-temperature side outlet of the high-temperature heat exchanger, the liquid outlet of the carbon dioxide absorption device is connected to the liquid inlet of the carbon dioxide release device, the gas outlet of the carbon dioxide release device is connected to the inlet of the high-temperature compressor, and the outlet of the high-temperature compressor is connected to the high-temperature carbon dioxide storage tank; the liquid outlet of the carbon dioxide release device is connected to the high-temperature side inlet of the high-temperature heat exchanger, which effectively ensures the secondary carbon capture of LNG coming out of the LNG source, improves the carbon capture capacity, reduces the carbon dioxide emissions of the thermal power plant, improves the operating efficiency of the thermal power plant, and fully utilizes the cold energy of LNG to reduce energy waste.

[0040] The present invention provides a method for the comprehensive utilization of LNG cold energy for carbon capture and dry ice production in thermal power plants. LNG from an LNG source undergoes four modules, namely, low-temperature, medium-temperature, high-temperature, and a cooling tower, before being gasified. The large amount of high-grade cold energy contained therein is utilized step by step during this process, and the LNG temperature continues to rise. A temperature sensor is installed after the cooling tower. If the LNG temperature at this time meets the user's needs, it is directly sent to the user's pipeline network. Otherwise, it is further heated through a seawater heat exchanger before being sent to the user's pipeline network. After the flue gas generated on the flue gas side of the thermal power plant undergoes two-stage carbon capture in the low-temperature carbon capture module and the high-temperature carbon capture module, the amount of carbon dioxide contained therein can be significantly reduced. At the same time, the system is equipped with a medium-temperature cold energy storage module. During peak gas usage periods, it stores LNG cold energy and dry ice cold energy that cannot be consumed by the system. During low gas usage periods, the stored cold energy is used to continue carbon capture, thus ensuring the continuity and stability of the system's operation. Based on the production characteristics of thermal power plants, the system comprehensively utilizes the large amount of high-grade cold energy contained in LNG. While reducing carbon dioxide emissions from thermal power plants and improving their operating efficiency, it fully utilizes LNG cold energy and reduces energy waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the LNG cold energy utilization system for carbon capture in thermal power plants according to the present invention;

[0042] In the figure: 1-LNG source; 2-low-temperature carbon capture module; 3-medium-temperature cold energy storage module; 4-high-temperature carbon capture module; 5-cooling tower; 6-LNG pipeline temperature sensor; 7-seawater heat exchanger; 201-first low-temperature heat exchanger; 202-first low-temperature compressor; 203-low-temperature carbon dioxide storage tank; 204-expander; 205-second low-temperature compressor; 206-second low-temperature heat exchanger; 207-dry ice collection device; 208-dry ice storage device; 301-medium-temperature heat exchanger; 302-cold energy storage device; 401-high-temperature heat exchanger; 402-carbon dioxide absorption device; 403-carbon dioxide release device; 404-high-temperature carbon dioxide storage tank; 405-electric heating device; 406-high-temperature compressor; 407-high-temperature temperature sensor. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0044] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0045] The present invention is described in further detail below with reference to the accompanying drawings:

[0046] The purpose of the present invention is to provide a system and method for comprehensive utilization of LNG cold energy for carbon capture and dry ice production in thermal power plants, so as to solve the technical problem of how to utilize the large amount of cold energy released during the LNG gasification process to reduce carbon dioxide emissions from thermal power plants and improve the operating efficiency of thermal power plants.

[0047] Example 1

[0048] See also Figure 1In one embodiment of the present invention, a LNG cold energy comprehensive utilization system for carbon capture and dry ice production in a thermal power plant is provided, comprising an LNG source 1, a low-temperature carbon capture module 2, a medium-temperature cold energy storage module 3, a high-temperature carbon capture module 4, a cooling tower 5, and a seawater heat exchanger 7;

[0049] The output of LNG source 1 is connected to the input of low-temperature carbon capture module 2, which is in turn connected to the input of medium-temperature cold energy storage module 3. The output of medium-temperature cold energy storage module 3 is connected to the input of high-temperature carbon capture module 4, which is then connected to the input of cooling tower 5. An LNG pipeline temperature sensor 6 is located at the output of cooling tower 5. The output of cooling tower 5 branches after passing through LNG pipeline temperature sensor 6, with one branch connected to the user pipeline network and the other branch connected to the user pipeline network via seawater heat exchanger 7. The two-stage carbon capture module achieves carbon capture of power plant flue gas, while the cold energy storage technology, cooling tower 5, and other technologies contribute to the full and efficient utilization of LNG cold energy.

[0050] Specifically, the low-temperature carbon capture module 2 includes a first low-temperature heat exchanger 201 , an expander 204 , a second low-temperature compressor 205 and a second low-temperature heat exchanger 206 ;

[0051] The low-temperature side inlet of the first low-temperature heat exchanger 201 is connected to the output end of the LNG source 1, and the low-temperature side outlet of the first low-temperature heat exchanger 201 is connected to the medium-temperature cold energy storage module 3;

[0052] The inlet of the second low-temperature compressor 205 is connected to the flue gas of the thermal power plant; the outlet of the second low-temperature compressor 205 is connected to the high-temperature side inlet of the second low-temperature heat exchanger 206, and the high-temperature side outlet of the second low-temperature heat exchanger 206 is connected to the high-temperature side inlet of the first low-temperature heat exchanger 201;

[0053] The high temperature side outlet of the first low temperature heat exchanger 201 is connected to the low temperature side inlet of the second low temperature heat exchanger 206 , the low temperature side outlet of the second low temperature heat exchanger 206 is connected to the inlet of the expander 204 , and the outlet of the expander 204 is connected to the high temperature carbon capture module 4 .

[0054] In this embodiment, after the flue gas flows through the second low-temperature compressor 205 and the second low-temperature heat exchanger 206, high-boiling point gases such as sulfur dioxide and sulfur trioxide in the flue gas are first liquefied and separated, and the remaining components flow into subsequent devices.

[0055] The low-temperature carbon capture module 2 further includes a first low-temperature compressor 202, a low-temperature carbon dioxide storage tank 203, a dry ice collection device 207 and a dry ice storage device 208;

[0056] The input end of the dry ice collection device 207 is connected to the output end of the first low-temperature heat exchanger 201, the output end of the dry ice collection device 207 is connected to the input end of the dry ice storage device 208, and the gas outlet of the dry ice storage device 208 is connected to the inlet of the first low-temperature compressor 202; the outlet of the first low-temperature compressor 202 is connected to the low-temperature carbon dioxide storage tank 203; the dry ice storage device 208 is connected to the medium-temperature cold energy storage module 3 via a circulation loop, wherein the outer surface of the circulation loop is covered with insulation material and a heat exchange component is provided inside.

[0057] In this embodiment, the large amount of dry ice collected by dry ice storage device 208 can be used for artificial rainmaking, cryogenic freezing, and other applications, further utilizing cold energy. Dry ice storage device 208 is connected to cold energy storage device 302 via a switchable circulation loop loaded with a suitable refrigerant. When the cold storage material in cold energy storage device 302 is low and the dry ice storage device 208 has a large amount of dry ice, this circulation loop can be activated to further replenish the cold energy stored in cold energy storage device 302.

[0058] Specifically, the medium-temperature cold energy storage module 3 includes a medium-temperature heat exchanger 301 and a cold energy storage device 302;

[0059] The low-temperature side inlet of the medium-temperature heat exchanger 301 is connected to the low-temperature side outlet of the first low-temperature heat exchanger 201; the low-temperature side outlet of the medium-temperature heat exchanger 301 is connected to the high-temperature carbon capture module 4;

[0060] The high-temperature side inlet of the medium-temperature heat exchanger 301 is connected to the output end of the cold energy storage device 302, and the high-temperature side outlet of the medium-temperature heat exchanger 301 is connected to the input end of the cold energy storage device 302, forming a circulation loop; wherein the outer surface of the circulation loop is covered with a heat-insulating material, and a heat exchange component is provided inside;

[0061] The cold energy storage device 302 is connected to the dry ice storage device 208 via a circulation loop.

[0062] In this embodiment, appropriate cold storage materials are arranged in the cold energy storage device 302, such as phase change cold storage materials such as eutectic salt.

[0063] In this embodiment, the medium-temperature heat exchanger 301 is connected in a multi-stage sequential circulation loop.

[0064] Specifically, the high-temperature carbon capture module 4 includes a high-temperature heat exchanger 401, a carbon dioxide absorption device 402, a carbon dioxide release device 403, a high-temperature carbon dioxide storage tank 404 and a high-temperature compressor 406;

[0065] The low-temperature side inlet of the high-temperature heat exchanger 401 is connected to the low-temperature side outlet of the medium-temperature heat exchanger 301; the low-temperature side outlet of the high-temperature heat exchanger 401 is connected to the inlet of the cooling tower 5;

[0066] The gas inlet of the carbon dioxide absorption device 402 is connected to the outlet of the expander 204; the gas outlet of the carbon dioxide absorption device 402 is connected to the flue gas treatment device or discharged;

[0067] The liquid inlet of the carbon dioxide absorption device 402 is connected to the high-temperature side outlet of the high-temperature heat exchanger 401, the liquid outlet of the carbon dioxide absorption device 402 is connected to the liquid inlet of the carbon dioxide release device 403, the gas outlet of the carbon dioxide release device 403 is connected to the inlet of the high-temperature compressor 406, and the outlet of the high-temperature compressor 406 is connected to the high-temperature carbon dioxide storage tank 404; the liquid outlet of the carbon dioxide release device 403 is connected to the high-temperature side inlet of the high-temperature heat exchanger 401.

[0068] The pipe between the liquid inlet of the carbon dioxide absorption device 402 and the high-temperature side outlet of the high-temperature heat exchanger 401 is connected to the bypass of the cold energy storage device 302. The outer surface of the bypass is wrapped with insulation material and a heat exchange component is installed inside. When the LNG flow rate is small and the cold energy provided is insufficient to meet the carbon capture needs of the thermal power plant, the cold energy of the cold energy storage device 302 is used to continue carbon capture.

[0069] Specifically, a spray device is provided at the liquid inlet end of the carbon dioxide absorption device 402 to make the absorption liquid fall evenly in the carbon dioxide absorption device 402 in the form of droplets.

[0070] In this embodiment, the liquid inlet of the carbon dioxide absorption device 402 flows into the absorption liquid that can absorb carbon dioxide. The inlet of the carbon dioxide absorption device 402 is provided with a spray device of appropriate form and number, so that the absorption liquid falls evenly in the form of droplets in the carbon dioxide absorption device 402, thereby increasing the contact area between the absorption liquid and the flue gas, thereby ensuring a good absorption effect of carbon dioxide.

[0071] In this embodiment, the absorption liquid specifically includes an alcoholamine solution, such as diethanolamine (DEA), triethanolamine (TEA), N-methyldiethanolamine (MDEA) solution, etc.

[0072] Specifically, the pipeline between the outlet of the high-temperature compressor 406 and the high-temperature carbon dioxide storage tank 404 is provided through the carbon dioxide release device 403, wherein a heat exchange component is provided inside the pipeline for heating the rich liquid after absorbing carbon dioxide to ensure that the carbon dioxide is completely released. The outer surface of the pipeline between the outlet of the high-temperature compressor 406 and the high-temperature carbon dioxide storage tank 404 is covered with a thermal insulation material and a high-temperature temperature sensor 407 is provided near the outlet of the high-temperature compressor 406 for monitoring the temperature of the high-pressure carbon dioxide flow in the pipeline; an electric heating device 405 is provided on the inner wall of the pipeline near the high-temperature temperature sensor 407. When the temperature of the high-pressure carbon dioxide flow in the pipeline is too low to heat the rich liquid to completely release the carbon dioxide, the electric heating device 405 is used to heat the high-pressure carbon dioxide flow in the pipeline to ensure that the carbon dioxide flow has a higher temperature.

[0073] In this embodiment, the water in cooling tower 5 is cooled by air as it falls into a sump, where it is then cooled again by the LNG cooling pipeline within the sump. This lowers the water temperature, creating a greater vacuum upon entering the condenser. This helps increase the effective enthalpy drop of the steam turbine, thereby improving the operating efficiency of the thermal power unit. The LNG pipeline within the sump of cooling tower 5 is connected to a temperature sensor 6. When the natural gas temperature meets user requirements, it is directly delivered to the user's pipeline network. If the temperature is still low, it enters a seawater heat exchanger 7 for further heating before being delivered to the user's pipeline network.

[0074] Example 2

[0075] The present invention also provides a method for comprehensively utilizing LNG cold energy for combined carbon capture and dry ice production in a thermal power plant. The method is based on the aforementioned system for comprehensively utilizing LNG cold energy for combined carbon capture and dry ice production in a thermal power plant, and includes the following steps:

[0076] The LNG in the output end of the LNG source 1 enters the low-temperature carbon capture module 2, wherein the operating temperature range of the low-temperature carbon capture module 2 is approximately -162°C to -100°C. The LNG exchanges heat in the first low-temperature heat exchanger 201, wherein the flue gas generated by the thermal power plant is first pressurized by the second low-temperature compressor 205 and then preliminarily cooled by the second low-temperature heat exchanger 206, and then enters the first low-temperature heat exchanger 201 for further cooling. At this time, the flue gas in the first low-temperature heat exchanger 201 undergoes two-stage cooling, and a large amount of carbon dioxide in the flue gas is directly condensed into dry ice and falls into the dry ice collection device 207, and then transported to the dry ice storage device 208. The remaining flue gas enters the expander 204 for decompression and cooling;

[0077] In the medium-temperature cold energy storage module 3, the operating temperature range of the medium-temperature cold energy storage module 3 is approximately -100°C to -20°C. The LNG that has undergone heat exchange enters the medium-temperature heat exchanger 301 for heat exchange. When the scale of LNG is large, multiple cold energy storage devices 302 can be set up in parallel pipelines, and appropriate cold storage materials, such as phase change cold storage materials such as eutectic salt, can be arranged therein; wherein the working medium flow direction of the medium-temperature heat exchanger 301 is set to countercurrent, and the dry ice storage device 208 is connected to the cold energy storage device 302 through a circulation loop loaded with an appropriate refrigerant. When the dry ice production exceeds the demand, this circulation loop can be activated to allow the dry ice and the cold storage material in the cold energy storage device 302 to exchange heat. After the heat exchange, the dry ice is sublimated into carbon dioxide, which is sent to the first low-temperature compressor 202 through a pipeline for pressurization and then enters the low-temperature carbon dioxide storage tank 203 for sealing;

[0078] In the high-temperature carbon capture module 4, the operating temperature range of the high-temperature carbon capture module 4 is about -20°C to 0°C. The flue gas in the low-temperature carbon capture module 2, after being decompressed and cooled by the expander 204, enters the carbon dioxide absorption device 402. The liquid inlet of the carbon dioxide absorption device 402 adopts a properly arranged spraying device to spray the absorption liquid. After contacting the absorption liquid, the remaining carbon dioxide in the flue gas is absorbed to form a rich liquid, and the remaining flue gas is discharged from the gas outlet of the carbon dioxide absorption device 402 to the atmosphere or other flue gas treatment devices; the rich liquid in the carbon dioxide absorption device 402 enters the carbon dioxide release device 403, and after being heated by the heat exchange component in the device, the absorption liquid releases carbon dioxide to form a lean liquid; the released carbon dioxide is passed through the high-temperature carbon capture module 403. After the warm compressor 406 increases the pressure and temperature, the temperature of the carbon dioxide in the pipeline is monitored by the high-temperature temperature sensor 407. When the temperature of the carbon dioxide in the pipeline is too low to heat the rich liquid to completely release the carbon dioxide, the carbon dioxide in the pipeline is heated by the electric heating device 405. The pressurized and heated carbon dioxide passes through the interior of the carbon dioxide release device 403. The portion of the pipeline inside the carbon dioxide release device 403 is provided with a heat exchange component for heating the rich liquid after absorbing carbon dioxide. The lean liquid flowing out of the carbon dioxide release device 403 enters the high-temperature side of the high-temperature heat exchanger 401, is cooled, and then passes again into the spray device in the carbon dioxide absorption device 402 to absorb carbon dioxide, thereby realizing the recycling of the absorption liquid.

[0079] There is a circulation loop connected to the cold energy storage device 302 in the pipeline between the high-temperature side outlet of the high-temperature heat exchanger 401 and the spray device in the carbon dioxide absorption device 402. When the amount of LNG is small, the amount of LNG reaching the high-temperature carbon capture module 4 is small and the temperature is high, which may not be enough to cool the absorption liquid. At this time, the bypass is activated to use the cold energy of the cold storage material in the cold energy storage device 302 to cool the absorption liquid, ensuring good working effect of the absorption liquid.

[0080] The natural gas temperature range in the cooling tower 5 is about 0℃~10℃. The low temperature side outlet of the high temperature heat exchanger 401 is connected to the cooling pipeline in the cooling tower 5. When the fourth level of utilization of LNG cold energy is completed in the cooling tower, the cooling tower pipeline is arranged in the water collection tank below the cooling tower 5. The water in the cooling tower 5 is cooled by air during the falling process and falls into the water collection tank. It is then cooled for the second time by the LNG cooling pipeline in the water collection tank. The water temperature at this time is relatively low, and a greater vacuum degree will be generated after entering the condenser, which helps to increase the effective enthalpy drop of the turbine and thus improve the operating efficiency of the thermal power unit; the LNG pipeline in the water collection tank of the cooling tower 5 is connected to the temperature sensor 6. When the natural gas temperature at this time meets the user's usage conditions, it is directly sent to the user pipeline network. If the temperature is still low, it enters the seawater heat exchanger 7 for further heating before being sent to the user pipeline network.

[0081] In this embodiment, when the flue gas enters the carbon dioxide absorption device 402, the temperature must be kept below a certain level, otherwise the absorption liquid may not absorb carbon dioxide effectively. Therefore, an expander 204 is provided to reduce the pressure and temperature. However, a reduction in the flue gas pressure may affect the normal operation of the entire pipeline and system. Therefore, a second low-temperature compressor 205 is provided to increase the pressure to ensure that the pressure after the pressure reduction is not too low, which may affect normal operation.

[0082] In summary, the present invention provides a system and method for comprehensive utilization of LNG cold energy for carbon capture and dry ice production in thermal power plants. A low-temperature carbon capture module, a medium-temperature cold energy storage module, a high-temperature carbon capture module, and a cooling tower are sequentially added after the LNG source. The low-temperature carbon capture module and the high-temperature carbon capture module are used for graded carbon capture. The two-stage carbon capture modules adopt different carbon capture principles and adapt to different temperature ranges, resulting in a good carbon capture effect. By setting up a medium-temperature cold energy storage module, cold energy can be stored when the thermal power plant cannot absorb all the cold energy during the peak gas consumption period. However, during the low gas consumption period, the cold energy stored in the cold energy storage device can be used to continue carbon capture, which is beneficial to the stable and efficient operation of the system. The present invention realizes the carbon capture process of the flue gas of the thermal power plant through the two-stage carbon capture module, and at the same time, cooperates with the cold energy storage technology and the cooling tower to realize the full and efficient utilization of the LNG cold energy.

[0083] The present invention matches the cooling energy required by the cooling tower with LNG cooling energy, and simultaneously utilizes LNG cooling energy for two-stage carbon capture of thermal power plant flue gas, effectively improving the carbon capture effect. The LNG cooling energy comprehensive utilization system provided by the present invention can not only capture carbon from thermal power plant flue gas, but also cool the water in the cooling tower, significantly improving the utilization rate of LNG cooling energy in the LNG cooling energy comprehensive utilization system and avoiding the increased cooling energy loss caused by the installation of multiple dispersed cooling energy use terminals. By providing a medium-temperature cold storage module, this system can ensure good and stable carbon capture effects even during periods of low LNG gas consumption.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A LNG cold energy comprehensive utilization system for carbon capture and dry ice production in thermal power plants, characterized by: It includes an LNG source (1), a low-temperature carbon capture module (2), a medium-temperature cold energy storage module (3), a high-temperature carbon capture module (4), a cooling tower (5) and a seawater heat exchanger (7); The output end of the LNG source (1) is connected to the input end of the low-temperature carbon capture module (2), the output end of the low-temperature carbon capture module (2) is connected to the input end of the medium-temperature cold energy storage module (3), the output end of the medium-temperature cold energy storage module (3) is connected to the input end of the high-temperature carbon capture module (4), the output end of the high-temperature carbon capture module (4) is connected to the input end of the cooling tower (5), and the output end of the cooling tower (5) is provided with an LNG pipeline temperature sensor (6), and the output end of the cooling tower (5) is branched after passing through the LNG pipeline temperature sensor (6), one branch is connected to the user pipeline network; the other branch is connected to the user pipeline network through the seawater heat exchanger (7); The low-temperature carbon capture module (2) comprises a first low-temperature heat exchanger (201), an expander (204), a second low-temperature compressor (205) and a second low-temperature heat exchanger (206); The low-temperature side inlet of the first low-temperature heat exchanger (201) is connected to the output end of the LNG source (1), and the low-temperature side outlet of the first low-temperature heat exchanger (201) is connected to the medium-temperature cold energy storage module (3); The inlet of the second low-temperature compressor (205) is connected to the flue gas of the thermal power plant; The outlet of the second low-temperature compressor (205) is connected to the high-temperature side inlet of the second low-temperature heat exchanger (206), and the high-temperature side outlet of the second low-temperature heat exchanger (206) is connected to the high-temperature side inlet of the first low-temperature heat exchanger (201); The high-temperature side outlet of the first low-temperature heat exchanger (201) is connected to the low-temperature side inlet of the second low-temperature heat exchanger (206), the low-temperature side outlet of the second low-temperature heat exchanger (206) is connected to the inlet of the expander (204), and the outlet of the expander (204) is connected to the high-temperature carbon capture module (4); The medium-temperature cold energy storage module (3) comprises a medium-temperature heat exchanger (301) and a cold energy storage device (302); The low-temperature side inlet of the medium-temperature heat exchanger (301) is connected to the low-temperature side outlet of the first low-temperature heat exchanger (201); the low-temperature side outlet of the medium-temperature heat exchanger (301) is connected to the high-temperature carbon capture module (4); The high-temperature side inlet of the medium-temperature heat exchanger (301) is connected to the output end of the cold energy storage device (302), and the high-temperature side outlet of the medium-temperature heat exchanger (301) is connected to the input end of the cold energy storage device (302), forming a circulation loop; wherein the outer surface of the circulation loop is covered with a heat-insulating material, and a heat exchange component is provided inside; The high-temperature carbon capture module (4) comprises a high-temperature heat exchanger (401), a carbon dioxide absorption device (402), a carbon dioxide release device (403), a high-temperature carbon dioxide storage tank (404) and a high-temperature compressor (406); The low-temperature side inlet of the high-temperature heat exchanger (401) is connected to the low-temperature side outlet of the medium-temperature heat exchanger (301); the low-temperature side outlet of the high-temperature heat exchanger (401) is connected to the inlet of the cooling tower (5); The gas inlet of the carbon dioxide absorption device (402) is connected to the outlet of the expander (204); the gas outlet of the carbon dioxide absorption device (402) is connected to the flue gas treatment device or discharged; The liquid inlet of the carbon dioxide absorption device (402) is connected to the high-temperature side outlet of the high-temperature heat exchanger (401), the liquid outlet of the carbon dioxide absorption device (402) is connected to the liquid inlet of the carbon dioxide release device (403), the gas outlet of the carbon dioxide release device (403) is connected to the inlet of the high-temperature compressor (406), and the outlet of the high-temperature compressor (406) is connected to the high-temperature carbon dioxide storage tank (404); the liquid outlet of the carbon dioxide release device (403) is connected to the high-temperature side inlet of the high-temperature heat exchanger (401).

2. The LNG cold energy comprehensive utilization system for carbon capture and dry ice production in thermal power plants according to claim 1, characterized in that: The low-temperature carbon capture module (2) further comprises a first low-temperature compressor (202), a low-temperature carbon dioxide storage tank (203), a dry ice collection device (207) and a dry ice storage device (208); The input end of the dry ice collection device (207) is connected to the output end of the first low-temperature heat exchanger (201), the output end of the dry ice collection device (207) is connected to the input end of the dry ice storage device (208), and the gas outlet of the dry ice storage device (208) is connected to the inlet of the first low-temperature compressor (202); the outlet of the first low-temperature compressor (202) is connected to the low-temperature carbon dioxide storage tank (203); the dry ice storage device (208) is connected to the medium-temperature cold energy storage module (3) through a circulation loop, wherein the outer surface of the circulation loop is covered with a heat-insulating material and a heat exchange component is provided inside.

3. The LNG cold energy comprehensive utilization system for carbon capture and dry ice production in thermal power plants according to claim 2, characterized in that: The cold energy storage device (302) is connected to the dry ice storage device (208) via a circulation loop.

4. The LNG cold energy comprehensive utilization system for carbon capture and dry ice production in thermal power plants according to claim 3, characterized in that: The pipeline between the liquid inlet of the carbon dioxide absorption device (402) and the high-temperature side outlet of the high-temperature heat exchanger (401) is connected to the bypass of the cold energy storage device (302), the outer surface of the bypass is wrapped with insulation material, and a heat exchange component is provided inside.

5. The LNG cold energy comprehensive utilization system for carbon capture and dry ice production in thermal power plants according to claim 4, characterized in that: The liquid inlet end of the carbon dioxide absorption device (402) is provided with a spraying device for making the carbon dioxide absorption liquid fall evenly in the carbon dioxide absorption device (402) in the form of droplets.

6. The LNG cold energy comprehensive utilization system for carbon capture and dry ice production in thermal power plants according to claim 5, characterized in that: The pipeline between the outlet of the high-temperature compressor (406) and the high-temperature carbon dioxide storage tank (404) passes through the carbon dioxide release device (403), wherein a heat exchange component is provided inside the pipeline for heating the rich liquid after absorbing carbon dioxide to ensure complete release of carbon dioxide; the outer surface of the pipeline between the outlet of the high-temperature compressor (406) and the high-temperature carbon dioxide storage tank (404) is covered with a heat-insulating material, and a high-temperature temperature sensor (407) is provided near the outlet of the high-temperature compressor (406) for monitoring the temperature of the high-pressure carbon dioxide flow in the pipeline; and an electric heating device (405) is provided on the inner wall of the pipeline near the high-temperature temperature sensor (407).

7. A method for comprehensive utilization of LNG cold energy by combining carbon capture with dry ice production in thermal power plants, characterized in that: The LNG cold energy comprehensive utilization system for carbon capture and dry ice production in thermal power plants according to claim 6 comprises the following process: The LNG in the output end of the LNG source (1) enters the low-temperature carbon capture module (2) and exchanges heat in the first low-temperature heat exchanger (201), wherein the flue gas generated by the thermal power plant first passes through the second low-temperature compressor (205) for pressurization and the second low-temperature heat exchanger (206) in sequence to be initially cooled, and then enters the first low-temperature heat exchanger (201) for further cooling. At this time, the flue gas in the first low-temperature heat exchanger (201) undergoes two-stage cooling, and a large amount of carbon dioxide in the flue gas is directly condensed into dry ice and falls into the dry ice collection device (207), and then transported to the dry ice storage device (208). The remaining flue gas enters the expander (204) for decompression and cooling; The LNG after heat exchange enters the medium-temperature heat exchanger (301) in the medium-temperature cold energy storage module (3) for heat exchange. When the scale of LNG is large, multiple cold energy storage devices (302) are set up by parallel pipelines, and appropriate cold storage materials are arranged therein; wherein the working medium flow direction of the medium-temperature heat exchanger (301) is set to countercurrent, and the dry ice storage device (208) is connected to the cold energy storage device (302) through a circulation loop loaded with appropriate refrigerant. When the dry ice production exceeds the demand, this circulation loop is activated to exchange heat between the dry ice and the cold storage material in the cold energy storage device (302). After the heat exchange, the dry ice is sublimated into carbon dioxide, which is sent to the first low-temperature compressor (202) through a pipeline for pressurization and then enters the low-temperature carbon dioxide storage tank (203) for sealing; The flue gas after being decompressed and cooled by the expander (204) in the low-temperature carbon capture module (2) enters the carbon dioxide absorption device (402) of the high-temperature carbon capture module (4). The liquid inlet of the carbon dioxide absorption device (402) is sprayed with absorption liquid by a properly arranged spraying device. After contacting the absorption liquid, the remaining carbon dioxide in the flue gas is absorbed to form a rich liquid. The remaining flue gas is discharged from the gas outlet of the carbon dioxide absorption device (402) to the atmosphere or other flue gas treatment devices; the rich liquid in the carbon dioxide absorption device (402) enters the carbon dioxide release device (403), and after being heated by the heat exchange component in the device, the absorption liquid releases carbon dioxide to form a lean liquid; the released carbon dioxide is subjected to the high-temperature compressor (406) for After the pressure is increased and the temperature is increased, the temperature of the carbon dioxide in the pipeline is monitored by a high-temperature temperature sensor (407). When the temperature of the carbon dioxide in the pipeline is too low to heat the rich liquid to completely release the carbon dioxide, the carbon dioxide in the pipeline is heated by an electric heating device (405). The carbon dioxide after the pressure increase and temperature increase passes through the interior of the carbon dioxide release device (403). A heat exchange component is provided in the carbon dioxide release device (403) to heat the rich liquid after absorbing the carbon dioxide. The lean liquid flowing out of the carbon dioxide release device (403) enters the high-temperature side of the high-temperature heat exchanger (401), is cooled, and then passes into the spray device in the carbon dioxide absorption device (402) to absorb the carbon dioxide, thereby realizing the recycling of the absorption liquid. A circulation loop connected to the cold energy storage device (302) exists in the pipeline between the high-temperature side outlet of the high-temperature heat exchanger (401) and the spray device in the carbon dioxide absorption device (402). When the amount of LNG is small, the amount of LNG reaching the high-temperature carbon capture module (4) is small and the temperature is high, which may not be enough to cool the absorption liquid. At this time, the bypass is activated to use the cold energy of the cold storage material in the cold energy storage device (302) to cool the absorption liquid, thereby ensuring a good working effect of the absorption liquid. The low-temperature side outlet of the high-temperature heat exchanger (401) is connected to the cooling pipeline in the cooling tower (5), and the fourth-level utilization of the LNG cold energy is completed in the cooling tower. The cooling tower pipeline is arranged in the water collection tank below the cooling tower (5). The water in the cooling tower (5) is cooled by air during the falling process and falls into the water collection tank. It is then cooled for the second time by the LNG cooling pipeline in the water collection tank. At this time, the water temperature is relatively low. After entering the condenser, a greater vacuum degree will be generated, which helps to increase the effective enthalpy drop of the turbine and thus improve the operating efficiency of the thermal power unit; the LNG pipeline in the water collection tank of the cooling tower (5) is connected to the temperature sensor (6). When the natural gas temperature at this time meets the user's usage conditions, it is directly sent to the user's pipeline network. If the temperature is still relatively low, it enters the seawater heat exchanger (7) for further heating before being sent to the user's pipeline network.

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