Carbon dioxide capture system applied to thermal power unit

Abstract

The application provides a carbon dioxide capturing system applied to a thermal power generating unit, comprising a membrane separation unit, a carbonation reaction unit, a cyclone separator, a carbon dioxide releasing unit, a first pipeline and a heat exchanger; the membrane separation unit is provided with an inlet, a first outlet and a second outlet, the inlet of the membrane separation unit is connected with a flue gas pipeline, and the first outlet of the membrane separation unit is connected with the inlet of the carbonation reaction unit; the outlet of the carbonation reaction unit is connected with the inlet of the cyclone separator; the first outlet of the cyclone separator is connected with the inlet of the carbon dioxide releasing unit; and the second outlet of the cyclone separator is connected with the heat exchanger through the first pipeline. One technical effect of the application is that not only the economy and effectiveness of carbon capturing can be improved, but also the comprehensive utilization efficiency of energy can be improved, so that technical support is provided for realizing a sustainable green development goal.

Description

Technical Field

[0001] This invention belongs to the field of boiler environmental protection and atmospheric environmental protection technology, specifically relating to a carbon dioxide capture system applied to thermal power units. Background Technology

[0002] To promote ecological civilization, many thermal power plants are actively preparing to build carbon capture (CC) systems. The main goal of CC systems is to effectively reduce carbon emissions from coal-fired power units, thereby contributing to the green transformation of the coal-fired power sector. However, existing CC systems on the market generally suffer from high energy consumption and low carbon dioxide capture capacity, making it difficult for companies building such systems to achieve economic benefits, thus hindering the promotion and industrial application of CC technology.

[0003] Furthermore, traditional thermal power units experience significant heat dissipation during operation and must also undertake peak power shaving tasks, leading to severe energy waste. In the renewable energy sector, wind and solar power generation suffer from instability, resulting in curtailment and further exacerbating energy waste. These problems not only reduce overall energy efficiency but also limit the utilization rate of clean energy. Therefore, finding efficient energy storage technologies to improve energy storage and reuse levels has become a key approach to enhancing energy efficiency and achieving energy conservation and emission reduction.

[0004] Therefore, there is an urgent need for a carbon dioxide capture system for thermal power units that combines low-energy carbon dioxide capture technology with high-efficiency energy storage and thermal storage technology, thereby improving the economy and effectiveness of carbon capture. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art and provide a new technical solution for carbon dioxide capture systems applied to thermal power units.

[0006] According to a first aspect of the present invention, a carbon dioxide capture system for thermal power units is provided, comprising a membrane separation unit, a carbonation reaction unit, a cyclone separator, a carbon dioxide release unit, a first pipeline, and a heat exchanger;

[0007] The membrane separation unit has an inlet, a first outlet, and a second outlet. The inlet of the membrane separation unit is connected to a flue gas duct, and the first outlet of the membrane separation unit is connected to the inlet of the carbonation reaction unit.

[0008] The outlet of the carbonation reaction unit is connected to the inlet of the cyclone separator; the first outlet of the cyclone separator is connected to the inlet of the carbon dioxide release unit.

[0009] The second outlet of the cyclone separator is connected to the heat exchanger via the first pipe;

[0010] Flue gas is separated into nitrogen and a mixed gas in the membrane separation unit. The nitrogen is output from the second outlet of the membrane separation unit, and the mixed gas enters the carbonation reaction unit through the first outlet of the membrane separation unit to undergo a chemical reaction. In this reaction, carbon dioxide in the mixed gas reacts with calcium oxide in the carbonation reaction unit to form solid calcium carbonate. The gas-solid mixture after the reaction undergoes gas-solid separation in the cyclone separator to obtain purified gas and solid calcium carbonate. The purified gas is output from the second outlet of the cyclone separator and exchanges heat with the liquid in the heat exchanger. The solid calcium carbonate enters the carbon dioxide release unit through the first outlet of the cyclone separator for heating and calcination to form carbon dioxide and calcium oxide.

[0011] Optionally, the carbon dioxide capture system applied to thermal power units also includes a gas storage tank;

[0012] The inlet of the gas storage tank is connected to the first outlet of the membrane separation unit, and the outlet of the gas storage tank is connected to the inlet of the carbonation reaction unit. The gas storage tank is used to store the mixed gas.

[0013] Optionally, the carbon dioxide capture system applied to thermal power units also includes a calcium oxide storage tank and a second pipeline;

[0014] One end of the second pipeline is connected to the first outlet of the carbon dioxide release unit, and the other end is connected to the carbonation reaction unit. The calcium oxide storage tank is installed in the second pipeline for storing calcium oxide.

[0015] The calcium oxide in the carbon dioxide release unit can be circulated into the carbonation reaction unit through the second pipeline.

[0016] Optionally, in the mixed gas, the concentration of carbon dioxide is 50%, the concentration of oxygen is 10%, and the concentration of nitrogen is 40%.

[0017] Optionally, the inlet of the membrane separation unit is located at the top of the membrane separation unit; the first outlet and the second outlet of the membrane separation unit are both located at the bottom of the membrane separation unit.

[0018] Optionally, the inlet of the carbonation reaction unit is located at the bottom of the carbonation reaction unit; the outlet of the carbonation reaction unit is located at the top of the carbonation reaction unit.

[0019] Optionally, the carbon dioxide capture system applied to thermal power units also includes a third pipeline;

[0020] One end of the third pipe is connected to the second outlet of the carbon dioxide release unit.

[0021] Optionally, the carbon dioxide capture system applied to thermal power units also includes a calcium carbonate storage tank;

[0022] The inlet of the calcium carbonate storage tank is connected to the first outlet of the cyclone separator, and the outlet of the calcium carbonate storage tank is connected to the inlet of the carbon dioxide release unit.

[0023] Optionally, the first outlet of the carbon dioxide release unit is located at the bottom of the carbon dioxide release unit; the second outlet of the carbon dioxide release unit is located at the top of the carbon dioxide release unit.

[0024] Optionally, the concentration of carbon dioxide in the flue gas is 13%, the concentration of oxygen is 6%, and the concentration of nitrogen is 81%.

[0025] One technical advantage of this invention is that:

[0026] In this embodiment, the membrane separation unit can enrich carbon dioxide in the flue gas, thereby increasing the carbonation reaction temperature under the same carbon capture efficiency conditions. Furthermore, some of the heat generated during the carbonation reaction is used for heat exchange with the liquid in the heat exchanger, thus improving energy utilization efficiency and grade. In addition, the energy source for this carbon dioxide capture system applied to thermal power units is the waste heat from the thermal power plant and the electricity generated from curtailed wind and solar power, achieving efficient utilization of electrical resources. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a carbon dioxide capture system applied to a thermal power unit according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram showing the change of CO2 partial pressure in the outlet gas of the carbonation reaction unit as a function of carbonation temperature, according to another embodiment of the present invention.

[0029] In the diagram: 1. Membrane separation unit; 2. Carbonation reaction unit; 3. Cyclone separator;

[0030] 4. Carbon dioxide release unit; 5. First pipeline; 6. Heat exchanger; 7. Gas storage tank;

[0031] 8. Calcium oxide storage tank; 9. Second pipeline; 10. Third pipeline; 11. Calcium carbonate storage tank. Detailed Implementation

[0032] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0033] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0034] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0035] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0036] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0037] According to a first aspect of the invention, see Figure 1 This invention provides a carbon dioxide capture system for thermal power units that combines low-energy CO2 capture technology with high-efficiency energy storage and thermal storage technology.

[0038] Specifically, the carbon dioxide capture system applied to thermal power units integrates a high-temperature calcium-based adsorbent in the membrane separation unit 1 and the carbonation reaction unit 2 to adsorb CO2. This allows the high-temperature calcium-based adsorbent to capture CO2 while also storing excess energy and releasing it when needed, thereby improving the overall energy utilization efficiency.

[0039] Specifically, the carbon dioxide capture system applied to thermal power units includes a membrane separation unit 1, a carbonation reaction unit 2, a cyclone separator 3, a carbon dioxide release unit 4, a first pipeline 5, and a heat exchanger 6.

[0040] The membrane separation unit 1 has an inlet, a first outlet, and a second outlet. The inlet of the membrane separation unit 1 is connected to the flue gas duct, and the first outlet of the membrane separation unit 1 is connected to the inlet of the carbonation reaction unit 2.

[0041] The outlet of the carbonation reaction unit 2 is connected to the inlet of the cyclone separator 3; the first outlet of the cyclone separator 3 is connected to the inlet of the carbon dioxide release unit 4.

[0042] The second outlet of the cyclone separator 3 is connected to the heat exchanger 6 through the first pipe 5.

[0043] Flue gas is separated into nitrogen and a mixed gas in the membrane separation unit 1. The nitrogen is output from the second outlet of the membrane separation unit 1, while the mixed gas enters the carbonation reaction unit 2 through the first outlet of the membrane separation unit 1 for a chemical reaction. Carbon dioxide in the mixed gas reacts with calcium oxide in the carbonation reaction unit 2 to form solid calcium carbonate. The resulting gas-solid mixture undergoes gas-solid separation in the cyclone separator 3 to obtain purified gas and solid calcium carbonate. The purified gas is output from the second outlet of the cyclone separator 3 and exchanges heat with the liquid in the heat exchanger 6. The solid calcium carbonate enters the carbon dioxide release unit 4 through the first outlet of the cyclone separator 3 for heating and calcination to form carbon dioxide and calcium oxide. The heating and calcination process utilizes waste heat from a thermal power plant or surplus wind and solar power as a heat source to improve resource utilization efficiency.

[0044] It should be emphasized that by treating the flue gas from the thermal power plant through the membrane separation unit 1, the carbon dioxide concentration at the inlet of the carbonation reaction unit 2 was significantly increased.

[0045] For example, membrane separation unit 1 is used to treat the flue gas from a thermal power plant, increasing the carbon dioxide concentration in the flue gas from 13% to 50%. Moreover, membrane separation unit 1 has the characteristics of high selectivity and low energy consumption, and can efficiently separate carbon dioxide.

[0046] Furthermore, the carbonation reaction unit 2 is filled with calcium oxide. The concentrated high-concentration carbon dioxide gas reacts with the calcium oxide (CaO) in the carbonation reaction unit 2 to produce calcium carbonate (CaCO3). This carbonation reaction releases a large amount of heat, which can be used for other processes or heating needs within the power plant. Next, waste heat from the thermal power plant or surplus wind and solar power is used as a heat source to heat and calcine the generated CaCO3, releasing high-concentration carbon dioxide and calcium oxide. The resulting carbon dioxide can be used for other industrial applications, while the calcium oxide can return to the carbonation reaction unit 2 to continue the carbonation reaction with high-concentration carbon dioxide, allowing for repeated recycling.

[0047] In this embodiment, the membrane separation unit 1 enriches carbon dioxide in the flue gas, increasing the carbonation reaction temperature of the carbonation reaction unit 2 under the same carbon capture efficiency. Furthermore, some of the heat generated during the carbonation reaction is used for heat exchange with the liquid in the heat exchanger 6, thereby improving energy utilization efficiency and grade. In addition, the energy source for this carbon dioxide capture system applied to thermal power units is the waste heat from the thermal power plant and the electricity generated from curtailed wind and solar power, achieving efficient utilization of electrical resources.

[0048] Therefore, this carbon dioxide capture system applied to thermal power units can not only improve the economy and effectiveness of carbon capture, but also enhance the overall energy utilization efficiency, thereby providing technical support for achieving sustainable green development goals.

[0049] Optionally, the carbon dioxide capture system applied to thermal power units also includes a gas storage tank 7;

[0050] The inlet of the gas storage tank 7 is connected to the first outlet of the membrane separation unit 1, and the outlet of the gas storage tank 7 is connected to the inlet of the carbonation reaction unit 2. The gas storage tank 7 is used to store the mixed gas.

[0051] In the above embodiments, the gas storage tank 7 can store the mixed gas, thereby facilitating the control of the carbonation reaction and simplifying operation.

[0052] Optionally, the carbon dioxide capture system applied to thermal power units also includes a calcium oxide storage tank 8 and a second pipeline 9;

[0053] One end of the second pipe 9 is connected to the first outlet of the carbon dioxide release unit 4, and the other end is connected to the carbonation reaction unit 2. The calcium oxide storage tank 8 is installed on the second pipe 9 and is used to store calcium oxide.

[0054] The calcium oxide in the carbon dioxide release unit 4 can be circulated into the carbonation reaction unit 2 through the second pipe 9.

[0055] In the above embodiments, the calcium oxide storage tank 8 can store calcium oxide, thereby facilitating the circulation of calcium oxide to the carbonation reaction unit 2 and controlling the carbonation reaction, making the operation simple.

[0056] Optionally, the concentration of carbon dioxide in the mixed gas is 50%, the concentration of oxygen is 10%, and the concentration of nitrogen is 40%. This enables the separation process of membrane separation unit 1 to enrich carbon dioxide in the flue gas, thereby realizing the energy utilization of the carbonation reaction.

[0057] Optionally, the inlet of the membrane separation unit 1 is located at the top of the membrane separation unit 1; the first outlet and the second outlet of the membrane separation unit 1 are both located at the bottom of the membrane separation unit 1. This makes the structural design of the membrane separation unit 1 more reasonable and facilitates the separation of flue gas.

[0058] Optionally, the inlet of the carbonation reaction unit 2 is located at the bottom of the carbonation reaction unit 2, and the outlet of the carbonation reaction unit 2 is located at the top of the carbonation reaction unit 2. This makes the structural design of the carbonation reaction unit 2 more reasonable and facilitates the carbonation reaction.

[0059] Optionally, the carbon dioxide capture system applied to thermal power units also includes a third pipeline 10;

[0060] One end of the third pipe 10 is connected to the second outlet of the carbon dioxide release unit 4.

[0061] In the above embodiment, carbon dioxide can be stably output through the third pipe 10, thereby realizing the consumption of carbon dioxide.

[0062] Optionally, the carbon dioxide capture system applied to thermal power units also includes a calcium carbonate storage tank 11;

[0063] The inlet of the calcium carbonate storage tank 11 is connected to the first outlet of the cyclone separator 3, and the outlet of the calcium carbonate storage tank 11 is connected to the inlet of the carbon dioxide release unit 4.

[0064] In the above embodiments, the calcium carbonate storage tank 11 can store calcium carbonate, thereby facilitating the control of calcium carbonate calcination.

[0065] Optionally, the first outlet of the carbon dioxide release unit 4 is located at the bottom of the carbon dioxide release unit 4; the second outlet of the carbon dioxide release unit 4 is located at the top of the carbon dioxide release unit 4. The carbon dioxide release unit 4 has a reasonable structural design, which facilitates the output of carbon dioxide and calcium oxide after the reaction.

[0066] Optionally, the concentration of carbon dioxide in the flue gas is 13%, the concentration of oxygen is 6%, and the concentration of nitrogen is 81%.

[0067] In one specific implementation, the working process of the carbon dioxide capture system applied to thermal power units is as follows:

[0068] First, the flue gas from the thermal power plant, after dust removal and dehydration (e.g., CO2 concentration of 13%, O2 concentration of 6%, and N2 concentration of 81%), enters the membrane separation unit 1 through the inlet. After separation by the membrane separation unit 1, two gases are formed: a CO2-enriched gas (i.e., a mixed gas with CO2 concentration of 50%, O2 concentration of 10%, and N2 concentration of 40%) and an N2-enriched gas (i.e., nitrogen).

[0069] Secondly, the CO2-enriched gas is stored in gas storage tank 7. When needed, the CO2-enriched gas in gas storage tank 7 is released from gas storage tank 7 and enters carbonation reaction unit 2 to react with CaO to generate purified gas and CaCO3. The gas-solid mixture after the reaction is discharged from the top of carbonation reaction unit 2 and, after gas-solid separation by cyclone separator 3, the purified gas is discharged from the top of cyclone separator 3. The purified gas carries heat and exchanges heat with the liquid to be heated in heat exchanger 6.

[0070] Finally, CaCO3 is discharged from the bottom of cyclone separator 3 and stored in calcium carbonate storage tank 11. When needed, the CaCO3 in calcium carbonate storage tank 11 is heated and calcined in carbon dioxide release unit 4. The generated CO2 is discharged from the top of carbon dioxide release unit 4, and the generated CaO is discharged from the bottom of carbon dioxide release unit 4 and stored in calcium oxide storage tank 8. The CaO in calcium oxide storage tank 8 is then transported to carbonation reaction unit 2 for reaction when needed to achieve the recycling of CaO.

[0071] It should be noted that the working principle of this carbon dioxide capture system applied to thermal power units is as follows:

[0072] (1) Energy storage-CaCO3 calcination-CO2 regeneration stage: Gas separation in membrane separation unit 1 requires driving force to achieve. The driving force of membrane separation unit 1 comes from the pre-compressor. Carbon dioxide release unit 4 also requires additional energy to heat and decompose the CaCO3 inside it. Therefore, when the thermal power plant needs to reduce peak load or has excess new energy curtailment of wind and solar power, the pre-compressor of membrane separation unit 1 and the heating equipment of carbon dioxide release unit 4 are started to consume excess power. The compressor drives the flue gas into membrane separation unit 1 to separate the flue gas. The gas enriched with CO2 is stored in gas storage tank 7, and the CaO formed after calcination of CaCO3 is stored in calcium oxide storage tank 8.

[0073] (2) Energy release-CaO carbonation-CO2 capture stage: When the thermal power plant needs to adjust peak load and increase load, the high concentration of CO2 in the gas storage tank 7 and the CaO in the calcium oxide storage tank 8 are released. The two react in the carbonation reaction unit 2. The heat generated after the reaction is carried away by the purified gas (i.e., to increase the boiler feedwater temperature and quickly increase the boiler load.

[0074] See Figure 2 The experimental data and results are as follows:

[0075] When membrane separation unit 1 is not used, the concentration of CO2 in the mixed gas at the inlet of carbonation reaction unit 2 is 13%. If the carbon capture efficiency of carbonation reaction unit 2 is 90%, the concentration of CO2 at the outlet of carbonation reaction unit 2 is approximately 1.3%.

[0076] When membrane separation unit 1 is used, the CO2 concentration in the mixed gas at the inlet of carbonation reaction unit 2 is 50%. Therefore, under the same carbon capture efficiency (90%), the CO2 concentration at the outlet of carbonation reaction unit 2 is 9%. This is based on the carbonation reaction temperature. Figure 2 It can be seen that by adding membrane separation unit 1, the carbonation reaction temperature can be increased from 650℃ to 750℃, thereby significantly improving the quality of heat energy utilization.

[0077] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A carbon dioxide capture system for thermal power units, characterized in that, It includes a membrane separation unit, a carbonation reaction unit, a cyclone separator, a carbon dioxide release unit, a first pipeline, and a heat exchanger; The membrane separation unit has an inlet, a first outlet, and a second outlet. The inlet of the membrane separation unit is connected to a flue gas duct, and the first outlet of the membrane separation unit is connected to the inlet of the carbonation reaction unit. The outlet of the carbonation reaction unit is connected to the inlet of the cyclone separator; the first outlet of the cyclone separator is connected to the inlet of the carbon dioxide release unit. The second outlet of the cyclone separator is connected to the heat exchanger via the first pipe; Flue gas is separated into nitrogen and a mixed gas in the membrane separation unit. The nitrogen is output from the second outlet of the membrane separation unit, and the mixed gas enters the carbonation reaction unit through the first outlet of the membrane separation unit to undergo a chemical reaction. In this reaction, carbon dioxide in the mixed gas reacts with calcium oxide in the carbonation reaction unit to form solid calcium carbonate. The gas-solid mixture after the reaction undergoes gas-solid separation in the cyclone separator to obtain purified gas and solid calcium carbonate. The purified gas is output from the second outlet of the cyclone separator and exchanges heat with the liquid in the heat exchanger. The solid calcium carbonate enters the carbon dioxide release unit through the first outlet of the cyclone separator for heating and calcination to form carbon dioxide and calcium oxide.

2. The carbon dioxide capture system for thermal power units according to claim 1, characterized in that, It also includes gas storage tanks; The inlet of the gas storage tank is connected to the first outlet of the membrane separation unit, and the outlet of the gas storage tank is connected to the inlet of the carbonation reaction unit. The gas storage tank is used to store the mixed gas.

3. The carbon dioxide capture system for thermal power units according to claim 2, characterized in that, It also includes calcium oxide storage tanks and a second pipeline; One end of the second pipeline is connected to the first outlet of the carbon dioxide release unit, and the other end is connected to the carbonation reaction unit. The calcium oxide storage tank is installed in the second pipeline for storing calcium oxide. The calcium oxide in the carbon dioxide release unit can be circulated into the carbonation reaction unit through the second pipeline.

4. The carbon dioxide capture system for thermal power units according to claim 3, characterized in that, In the mixture, the concentration of carbon dioxide is 50%, the concentration of oxygen is 10%, and the concentration of nitrogen is 40%.

5. The carbon dioxide capture system for thermal power units according to claim 4, characterized in that, The inlet of the membrane separation unit is located at the top of the membrane separation unit; the first outlet and the second outlet of the membrane separation unit are both located at the bottom of the membrane separation unit.

6. The carbon dioxide capture system for thermal power units according to claim 5, characterized in that, The inlet of the carbonation reaction unit is located at the bottom of the carbonation reaction unit; the outlet of the carbonation reaction unit is located at the top of the carbonation reaction unit.

7. The carbon dioxide capture system for thermal power units according to claim 6, characterized in that, It also includes a third pipeline; One end of the third pipe is connected to the second outlet of the carbon dioxide release unit.

8. The carbon dioxide capture system for thermal power units according to claim 7, characterized in that, This also includes calcium carbonate storage tanks; The inlet of the calcium carbonate storage tank is connected to the first outlet of the cyclone separator, and the outlet of the calcium carbonate storage tank is connected to the inlet of the carbon dioxide release unit.

9. The carbon dioxide capture system for thermal power units according to claim 8, characterized in that, The first outlet of the carbon dioxide release unit is located at the bottom of the carbon dioxide release unit; the second outlet of the carbon dioxide release unit is located at the top of the carbon dioxide release unit.

10. The carbon dioxide capture system for thermal power units according to claim 9, characterized in that, The concentration of carbon dioxide in the flue gas is 13%, the concentration of oxygen is 6%, and the concentration of nitrogen is 81%.

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