Carbon dioxide capture and energy storage system for coal-fired power plant and use method of carbon dioxide capture and energy storage system

Abstract

The invention provides a coal-fired power plant carbon dioxide capture and energy storage system and a use method thereof.The coal-fired power plant carbon dioxide capture and energy storage system comprises a low-temperature water washing module used for cooling flue gas to 0-10 DEG C and recovering moisture and pollutants in the flue gas; the flue gas compression module comprises a multi-stage compressor and an interstage heat exchanger and is used for compressing flue gas to 7-25 MPa and cooling the flue gas through the interstage heat exchanger; the carbon dioxide separation module is used for separating liquid carbon dioxide from high-pressure flue gas and storing the liquid carbon dioxide and the high-pressure flue gas in a liquid carbon dioxide storage tank; and the energy storage module comprises a compressed gas storage tank, and the gas-phase high-pressure gas separated by the separator is stored in the compressed gas storage tank. Carbon dioxide capture is achieved through the compression and cooling liquefaction process, compared with a traditional organic amine absorption method, energy consumption is lower, carbon dioxide capture and an energy storage system are organically combined, the system adjusting capacity is enhanced through the energy storage function, the system adapts to the fluctuation of new energy power generation, and the synergistic effect of carbon dioxide capture and energy storage is achieved through system innovation; wide application prospects are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon capture and energy storage, and in particular to a carbon dioxide capture and energy storage system for a coal-fired power plant and a method of using the system. Background Art

[0002] Climate change is an important issue of global concern, and coal-fired power plants are one of the main sources of carbon dioxide (CO2) emissions. In response to the emission reduction needs of coal-fired power plants, the more mature carbon dioxide capture technology is currently mainly the organic amine absorption method. However, the high energy consumption of this technology hinders its application in large-scale industrialization. At the same time, as the proportion of renewable energy power generation continues to increase, coal-fired power plants need to improve their flexibility to adapt to changes in grid load, thereby reducing the wind and solar power abandonment rate and enhancing the system's regulation capabilities. Therefore, it is urgent to develop a new carbon dioxide capture technology with high energy utilization efficiency and combined with energy storage. Summary of the invention

[0003] The purpose of the present invention is to provide a carbon dioxide capture and energy storage system for a coal-fired power plant and a method of using the same, which can capture carbon dioxide while utilizing the waste pressure energy of flue gas for energy storage, thereby improving the energy utilization efficiency of the system.

[0004] According to one object of the present invention, the present invention provides a carbon dioxide capture and energy storage system for a coal-fired power plant, comprising:

[0005] Low-temperature water washing module, used to cool the flue gas to 0-10℃ and recover moisture and pollutants in the flue gas;

[0006] The flue gas compression module includes a multi-stage compressor and an inter-stage heat exchanger, which is used to compress the flue gas to 7-25MPa and cool it through the inter-stage heat exchanger;

[0007] The carbon dioxide separation module separates the liquid carbon dioxide from the high-pressure flue gas and stores it in a liquid carbon dioxide storage tank;

[0008] The energy storage module comprises a compressed gas storage tank, in which the gas phase high pressure gas separated by the separator is stored;

[0009] Energy release module: the high-pressure gas in the compressed gas storage tank is converted into electrical energy output through an expansion device.

[0010] Furthermore, the cooling water temperature of the low-temperature water washing module is 0 to 10°C. After the flue gas and the cooling water undergo heat exchange, the flue gas temperature is reduced to 0 to 10°C, and the condensed water and some pollutants are sent to the boiler chemical water workshop through a collection water tank for purification and recycling.

[0011] Furthermore, the flue gas compression module includes a two-stage or multi-stage compressor, which compresses the flue gas into high-temperature and high-pressure flue gas, and exchanges heat with high-pressure and low-temperature water in a low-temperature water storage tank through an inter-stage heat exchanger to reduce the flue gas temperature to 0-10°C.

[0012] Furthermore, the carbon dioxide separation module includes a separator, which separates liquid carbon dioxide from gaseous high-pressure gas and stores the liquid carbon dioxide in the liquid carbon dioxide storage tank, while the gaseous high-pressure gas enters the compressed gas storage tank.

[0013] Furthermore, the liquid carbon dioxide in the liquid carbon dioxide storage tank is divided into two parts, one part of which is supplied to the outside through a pipeline or a tank truck, and the other part is converted into gaseous carbon dioxide through decompression expansion to be used as circulating water for the low-temperature water washing module.

[0014] Furthermore, the interstage heat exchanger of the flue gas compression module provides high-pressure low-temperature water of 2-3 MPa and 0-10°C through a low-temperature water storage tank, which exchanges heat with the compressed gas and heats up before entering a high-temperature water storage tank.

[0015] Furthermore, the expansion device includes at least two expansion units, and the high-pressure gas passes through the interstage heater and exchanges heat with high-temperature water before entering the expansion units in sequence to generate electricity.

[0016] Furthermore, the high-pressure gas stored in the compressed gas storage tank is heat exchanged with high-temperature water from the high-temperature water storage tank through the interstage heater to form a high-temperature and high-pressure gas of 200°C and 7-25MPa, which is then converted into electrical energy output through the first-stage expander; the expanded gas is heat exchanged with the high-temperature water again to form a high-temperature and high-pressure gas, which enters the second-stage expander to further perform work and generate electricity, and the exhausted gas is finally discharged through the exhaust chimney.

[0017] According to another object of the present invention, the present invention provides a method for using the above-mentioned coal-fired power plant carbon dioxide capture and energy storage system, comprising the following steps:

[0018] S1. Carbon dioxide capture

[0019] S101, low temperature water washing and preliminary treatment

[0020] The flue gas enters the low-temperature water washing module from the desulfurization tower and exchanges heat with 0-10℃ water;

[0021] The flue gas is cooled to 0-10℃, the moisture and some pollutants are condensed and recovered, and the condensate is recycled;

[0022] S102, Flue gas compression

[0023] The low-temperature flue gas is compressed to a high-temperature and high-pressure state by a first-stage compressor;

[0024] After being cooled in the first and second stage heat exchangers, the flue gas temperature is reduced and part of the liquid carbon dioxide is condensed;

[0025] S103, Separation and Storage

[0026] The gas phase high pressure gas and liquid carbon dioxide are separated in the separator, and the liquid carbon dioxide is stored in a storage tank;

[0027] S2. High-pressure gas energy storage

[0028] S201, High-pressure gas storage

[0029] The gas phase high pressure gas separated by the separator enters the compressed gas storage tank for storage;

[0030] Then it enters the expansion refrigerator to do work, and the gas and liquid phases are separated;

[0031] S202, high pressure gas expansion power generation

[0032] The high-pressure gas in the compressed gas storage tank is expanded in stages to generate electricity, and the exhaust gas is discharged through the exhaust chimney.

[0033] Furthermore, part of the liquid carbon dioxide in the liquid carbon dioxide storage tank is supplied to the outside through a pipeline or a tank truck, and the other part is converted into gaseous carbon dioxide through decompression and expansion to be used for circulating water of the low-temperature water washing module.

[0034] The technical solution of the present invention uses a compression and cooling liquefaction process to achieve carbon dioxide capture, which has lower energy consumption than the traditional organic amine absorption method, organically combines carbon dioxide capture with the energy storage system, and enhances the system's regulation ability through the energy storage function to adapt to the volatility of new energy power generation. The synergy of carbon dioxide capture and energy storage is achieved through system innovation, and the technology has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0037] In the figure: 1. Desulfurization tower; 2. Low-temperature water washing module; 3. Collecting water tank; 4. First-stage compressor; 5. Low-temperature water storage tank; 6. Second-stage compressor; 7. Interstage heat exchanger; 8. Separator; 9. Liquid carbon dioxide storage tank; 10. Compressed gas storage tank; 11. First-stage expander; 12. Second-stage expander; 13. High-temperature water storage tank; 14. Emission chimney. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0040] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] Example 1

[0042] like Figure 1 As shown,

[0043] A carbon dioxide capture and energy storage system for a coal-fired power plant, comprising the following modules:

[0044] Low-temperature water washing module: exchanges heat between flue gas and cold water close to zero degrees, cools the flue gas to 0-10°C, condenses and recovers moisture and pollutants in the flue gas;

[0045] Flue gas compression module: compresses flue gas through multi-stage compressors to form high-temperature and high-pressure flue gas, and cools the flue gas through inter-stage heat exchangers;

[0046] Carbon dioxide separation module: uses a separator to separate liquid carbon dioxide and stores it in a liquid carbon dioxide storage tank;

[0047] Energy storage module: The gas phase high pressure gas separated by the separator is stored in a compressed gas storage tank;

[0048] Energy release module: The high-pressure gas in the compressed gas storage tank is converted into electrical energy output through an expander.

[0049] Specifically, when the system captures CO2:

[0050] The tail gas from the desulfurization tower 1 enters the low-temperature water washing module 2, exchanges heat with low-temperature water at a temperature of 0-10°C, cools the flue gas to 0 to 10°C, condenses and recovers the moisture and some pollutants in the flue gas, and the condensate is sent to the boiler chemical water workshop through the collection water tank 3 for recycling after purification;

[0051] The cooled low-temperature flue gas enters the first-stage compressor 4 for compression to form high-temperature and high-pressure flue gas, which is then heat-exchanged with high-pressure and low-temperature water from the low-temperature water storage tank 5 through the interstage heat exchanger to cool the flue gas to 40-50°C, further condensing the moisture in the flue gas.

[0052] The flue gas then enters the secondary compressor 6, where it is compressed to form high-temperature and high-pressure flue gas of 7-25MPa and 200-300°C. It is cooled again by heat exchange with high-pressure and low-temperature water through the second interstage heat exchanger 7. The flue gas temperature is reduced to 0-10°C, and part of the liquid carbon dioxide condenses and enters the separator 8 together with the gaseous high-pressure gas.

[0053] The separator 8 separates the liquid carbon dioxide from the gaseous high-pressure gas. The liquid carbon dioxide is discharged and stored in the liquid carbon dioxide storage tank 9, and the gaseous high-pressure gas is discharged from the top of the separator into the compressed gas storage tank 10.

[0054] In this embodiment, the carbon dioxide separation module includes a separator and a liquid carbon dioxide storage tank. The gas-liquid separator is connected to the flue gas compression module. The liquid carbon dioxide is separated by the separator and stored in the liquid carbon dioxide storage tank.

[0055] Part of the liquid carbon dioxide in the liquid carbon dioxide storage tank will be supplied to the outside through pipelines or tank trucks, and the other part will be reduced in pressure and expanded to become gaseous carbon dioxide of about 0.5-0.7MPa, -10-0℃ for cooling the circulating water of the low-temperature water washing module;

[0056] In this embodiment, the interstage heat exchanger arranged between the compressors provides high-pressure low-temperature water of about 2-3 MPa and 0-10°C through the low-temperature water storage tank 20, and the high-temperature water after heat exchange and temperature increase enters the high-temperature water storage tank.

[0057] Specifically: When the system performs high-pressure gas energy storage:

[0058] The high-pressure gas in the compressed gas storage tank 10 passes through the interstage heater and exchanges heat with the high-temperature water from the high-temperature water storage tank 13 to form a high-temperature and high-pressure gas of 200°C and 7-25MPa and enters the first-stage expander 11 to generate power;

[0059] The expanded gas is again heat-exchanged with high-temperature water from the high-temperature water storage tank 13 to form high-temperature and high-pressure gas, which enters the secondary expander 12 to further perform work and generate electricity, and the exhaust gas is finally discharged through the exhaust chimney 14.

[0060] Specifically: System circulation cooling:

[0061] Part of the liquid carbon dioxide in the liquid carbon dioxide storage tank 9 is expanded by decompression to form gaseous carbon dioxide at 0.5 to 0.7 MPa and -10 to 0° C., which serves as a coolant for the low-temperature water washing circulating water.

[0062] The present invention uses cold water close to zero degrees to clean the flue gas and recover the moisture in the flue gas; captures the carbon dioxide in the flue gas by compressing the tail gas of the coal-fired power plant and cooling it down, and uses the high-pressure flue gas after the carbon dioxide is removed by pressurization for energy storage, thereby realizing the reuse of the high-pressure gas, reducing energy consumption, and recovering the moisture in the flue gas. The system is simple and has a high energy utilization rate.

[0063] Compared with the traditional carbon dioxide capture system of coal-fired power plants, the present invention adopts a compression, cooling and liquefaction process to capture carbon dioxide in flue gas, and utilizes the steam or electricity of the thermal power plant itself to have the characteristics of high energy utilization rate; the system couples carbon dioxide capture with the energy storage system, and while capturing carbon dioxide, it utilizes the pressure energy of the waste flue gas for energy storage. It is a large-scale long-term energy storage system, and its combination with new energy systems such as photovoltaic and wind power is conducive to suppressing the volatility of new energy.

[0064] The present invention is based on an integrated system of flue gas liquefaction energy storage and carbon dioxide capture, which solves the problems of high carbon emissions and low energy utilization in existing coal-fired power plants, and provides a new technical path for achieving the goal of low-carbon and sustainable development.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A carbon dioxide capture and energy storage system for a coal-fired power plant, characterized in that: include: Low-temperature water washing module, used to cool the flue gas to 0-10℃ and recover moisture and pollutants in the flue gas; The flue gas compression module includes a multi-stage compressor and an inter-stage heat exchanger, which is used to compress the flue gas to 7-25MPa and cool it through the inter-stage heat exchanger; The carbon dioxide separation module separates the liquid carbon dioxide from the high-pressure flue gas and stores it in a liquid carbon dioxide storage tank; The energy storage module comprises a compressed gas storage tank, in which the gas phase high pressure gas separated by the separator is stored; Energy release module: the high-pressure gas in the compressed gas storage tank is converted into electrical energy output through an expansion device.

2. The carbon dioxide capture and energy storage system for coal-fired power plants according to claim 1, characterized in that: The cooling water temperature of the low-temperature water washing module is 0 to 10°C. After the flue gas and the cooling water undergo heat exchange, the flue gas temperature is reduced to 0 to 10°C, and the condensed water and some pollutants are sent to the boiler chemical water workshop through a collection water tank for purification and recycling.

3. The carbon dioxide capture and energy storage system for coal-fired power plants according to claim 1, characterized in that: The flue gas compression module includes a two-stage or multi-stage compressor, which compresses the flue gas into high-temperature and high-pressure flue gas, and exchanges heat with high-pressure and low-temperature water in a low-temperature water storage tank through an inter-stage heat exchanger to reduce the flue gas temperature to 0-10°C.

4. The carbon dioxide capture and energy storage system for coal-fired power plants according to claim 1, characterized in that: The carbon dioxide separation module comprises a separator, which separates liquid carbon dioxide from gaseous high-pressure gas and stores the liquid carbon dioxide in the liquid carbon dioxide storage tank, while the gaseous high-pressure gas enters the compressed gas storage tank.

5. The carbon dioxide capture and energy storage system for coal-fired power plants according to claim 1, characterized in that: The liquid carbon dioxide in the liquid carbon dioxide storage tank is divided into two parts, one part of which is supplied to the outside through a pipeline or a tank truck, and the other part is converted into gaseous carbon dioxide after decompression expansion to be used as circulating water for the low-temperature water washing module.

6. The carbon dioxide capture and energy storage system for coal-fired power plants according to claim 1, characterized in that: The interstage heat exchanger of the flue gas compression module provides high-pressure low-temperature water of 2-3 MPa and 0-10°C through a low-temperature water storage tank, which exchanges heat with the compressed gas and heats up before entering the high-temperature water storage tank.

7. The carbon dioxide capture and energy storage system for coal-fired power plants according to claim 1, characterized in that: The expansion device comprises at least two expansion units, and the high-pressure gas passes through the interstage heater and exchanges heat with high-temperature water before entering the expansion units in sequence to generate electricity.

8. The carbon dioxide capture and energy storage system for coal-fired power plants according to claim 1, characterized in that: The high-pressure gas stored in the compressed gas storage tank is heat exchanged with the high-temperature water from the high-temperature water storage tank through the interstage heater to form a high-temperature and high-pressure gas of 200°C and 7-25MPa, which is then converted into electrical energy output through the first-stage expander; the expanded gas is heat exchanged with the high-temperature water again to form a high-temperature and high-pressure gas, which enters the second-stage expander to further perform work and generate electricity, and the exhausted gas is finally discharged through the exhaust chimney.

9. The method for using the carbon dioxide capture and energy storage system of a coal-fired power plant according to claim 1, characterized in that: The steps include: S1. Carbon dioxide capture S101, low temperature water washing and preliminary treatment The flue gas enters the low-temperature water washing module from the desulfurization tower and exchanges heat with 0-10℃ water; The flue gas is cooled to 0-10℃, the moisture and some pollutants are condensed and recovered, and the condensate is recycled; S102, Flue gas compression The low-temperature flue gas is compressed to a high-temperature and high-pressure state by a first-stage compressor; After being cooled in the first and second stage heat exchangers, the flue gas temperature is reduced and part of the liquid carbon dioxide is condensed; S103, Separation and Storage The gas phase high pressure gas and liquid carbon dioxide are separated in the separator, and the liquid carbon dioxide is stored in a storage tank; S2. High-pressure gas energy storage S201, High-pressure gas storage The gas phase high pressure gas separated by the separator enters the compressed gas storage tank for storage; Then it enters the expansion refrigerator to do work, and the gas and liquid phases are separated; S202, high pressure gas expansion power generation The high-pressure gas in the compressed gas storage tank is expanded in stages to generate electricity, and the exhaust gas is discharged through the exhaust chimney.

10. The method for using the carbon dioxide capture and energy storage system of a coal-fired power plant according to claim 9, characterized in that: A part of the liquid carbon dioxide in the liquid carbon dioxide storage tank is supplied to the outside through a pipeline or a tank truck, and the other part is converted into gaseous carbon dioxide through decompression and expansion to be used for circulating water of the low-temperature water washing module.

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