Solid calcium-based carbon dioxide trapping system coupled with coal-fired boiler and method thereof

Abstract

The invention discloses a solid calcium-based carbon dioxide trapping system coupled with a coal-fired boiler and a method thereof, and belongs to the technical field of environmental protection. According to the system, a fixed bed is adopted as a reactor for absorbing CO2, CaO solid is adopted as a CO2 adsorbent, a large amount of water does not need to be consumed, and meanwhile the problem that a liquid chemical reagent serves as the CO2 adsorbent can be effectively solved. The system can efficiently capture CO2 and realize regeneration of the solid calcium-based absorbent through a fixed bed technology. And the vast majority of heat of high-temperature flue gas generated by the hot smoke generator is coupled with the coal-fired boiler, so that not only is the efficient recovery of energy promoted, but also the energy consumption of CO2 capture is remarkably reduced, and an economical and feasible strategy is provided for realizing the low-carbon target. According to the technical scheme provided by the invention, efficient capture of carbon dioxide in the flue gas discharged by the coal-fired power plant can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and in particular relates to a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler. Background Art

[0002] Carbon dioxide capture technology is divided into pre-combustion capture, post-combustion capture, oxygen-enriched combustion, etc. Pre-combustion capture and oxygen-enriched combustion have great restrictions on the application of coal-fired boilers and are difficult to apply to operating boilers. Post-combustion capture has little impact on coal-fired units. Among them, liquid chemical absorption is one of the most mature and widely used technologies. It uses the chemical reaction between chemical reagents and carbon dioxide to separate CO2 from flue gas. This technology is basically mature and has been demonstrated on a small scale. This technology generally has the problem of high energy consumption. The chemical absorption method requires more energy during the absorption and regeneration process, especially the regeneration process of the absorbent, which may lead to high overall energy consumption. Due to energy consumption and chemical use, the operating cost of the chemical absorption method is relatively high, which limits its economic feasibility on a larger scale. The absorbent may have a certain impact on the environment, such as the emission of volatile organic compounds and corrosion to equipment. Long-term operation may cause equipment corrosion and blockage problems, increase maintenance costs and operational complexity.

[0003] For example, the patent document CN117839379A published on April 9, 2024, discloses a high-pressure chemical chain coupled calcium cycle carbon dioxide capture system and its application, which is not suitable for coal-fired units. For example, the patent document CN114522533A published on May 24, 2022, discloses a calcium-based heat carrier circulating flue gas carbon dioxide capture system and method. The system uses cyclone separation to achieve calcium-based cycle capture of carbon dioxide, but the system introduces high-pressure air fluidization calcium-based absorbent, introduces air, increases system energy consumption, and affects the purity of captured carbon dioxide. For example, the patent document CN114405247A published on April 29, 2022, discloses a carbon dioxide capture system, which uses a calcium-based carbon dioxide capture system with an air compressor, which is also not suitable for carbon dioxide capture from coal-fired units.

[0004] Therefore, the present invention aims to develop an innovative CO2 capture method, aiming to reduce energy consumption, improve environmental compatibility, avoid equipment corrosion, and enhance system stability, in order to achieve better economic and environmental benefits. Summary of the invention

[0005] The purpose of the present invention is to provide a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler, which uses a fixed bed as a reactor for absorbing CO2, and the CO2 adsorbent uses CaO solid, which does not require the consumption of a large amount of water and can effectively avoid the problem of using liquid chemical reagents as CO2 adsorbents.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler, the carbon dioxide capture system comprising a high-temperature flue gas generator, a high-temperature regenerative furnace assembly, a fixed bed assembly, a CO2 storage assembly and a boiler assembly;

[0008] The high temperature flue gas generator is used to provide high temperature flue gas for the high temperature regenerative furnace assembly;

[0009] The high temperature heat storage furnace assembly is used to provide heat to the fixed bed assembly and the boiler assembly respectively;

[0010] The fixed bed assembly is used to store CaCO3 particles, and after decomposing CO2 and CaO under the action of heat, the CO2 is sent to the CO2 storage assembly for storage. The CO2 storage assembly is used to provide heating energy for the high-temperature heat storage furnace assembly.

[0011] The boiler assembly is used to generate flue gas under the action of heat and send it to the fixed bed assembly to react with CaO to remove CO2 in the flue gas.

[0012] Furthermore, in another preferred embodiment, the high temperature heat storage furnace assembly comprises a first high temperature heat storage furnace and a second high temperature heat storage furnace;

[0013] The fixed bed assembly includes a first fixed bed, a second fixed bed and a waste heat recovery device;

[0014] The first fixed bed and the second fixed bed are both connected to a waste heat recovery device;

[0015] The first fixed bed is connected to the first high-temperature heat storage furnace, and the second fixed bed is connected to the second high-temperature heat storage furnace.

[0016] Further, there is a preferred embodiment, the CO2 storage assembly comprises a first CO2 cooler, a CO2 booster fan, a second CO2 cooler, a CO2 booster device and a CO2 storage tank;

[0017] The first CO2 cooler and the second CO2 cooler are both connected to the fixed bed assembly;

[0018] The second CO2 cooler is connected to the CO2 storage tank via the CO2 booster device;

[0019] The CO2 storage tank and the first CO2 cooler are both connected to the CO2 booster fan;

[0020] The CO2 booster fan is connected to the first high-temperature heat storage furnace and the second high-temperature heat storage furnace respectively.

[0021] Furthermore, in a preferred embodiment, the boiler assembly comprises a coal-fired boiler, a dust collector and a desulfurization tower;

[0022] Coal-fired boilers are used to generate flue gas by heat and send it to the dust collector;

[0023] The dust collector removes dust from the flue gas and sends it to the desulfurization tower for desulfurization treatment;

[0024] The desulfurization tower sends the desulfurized flue gas to the fixed bed assembly.

[0025] Furthermore, in a preferred embodiment, the system is further provided with a plurality of valves.

[0026] Furthermore, there is a preferred embodiment in which carbon dioxide capture is achieved by opening and closing the above-mentioned multiple valves.

[0027] Furthermore, there is a preferred embodiment in which the opening and closing of the above-mentioned multiple valves are achieved through a control system.

[0028] The present invention also provides a solid calcium-based carbon dioxide capture method coupled to a coal-fired boiler. The carbon dioxide capture method is implemented based on any one of the solid calcium-based carbon dioxide capture systems coupled to a coal-fired boiler described above. The carbon dioxide capture method specifically comprises the following steps:

[0029] Step 1: Add solid CaCO3 particles into the first fixed bed and the second fixed bed respectively, and close all valves;

[0030] Step 2: Open the valves between the high-temperature flue gas generator and the first high-temperature regenerative furnace, between the first high-temperature regenerative furnace and the first fixed bed, at the outlet of the first fixed bed, and between the CO2 booster and the CO2 storage tank, start the high-temperature flue gas generator, and heat the regenerative body in the first high-temperature regenerative furnace with the high-temperature flue gas. At the same time, use the high-temperature flue gas to heat the CaCO3 particles in the first fixed bed to decompose them into CO2 and CaO. The CO2 is first cooled by the second CO2 cooler, and then pressurized by the CO2 booster and stored in the CO2 storage tank.

[0031] Step 3: Close the valves between the first high-temperature heat storage furnace and the first fixed bed and at the outlet of the first fixed bed, open the valves between the high-temperature flue gas generator and the second high-temperature heat storage furnace, between the second high-temperature heat storage furnace and the coal-fired boiler, between the desulfurization tower and the first fixed bed, and between the first fixed bed and the waste heat recovery device, start the high-temperature flue gas generator, and the high-temperature flue gas heats the heat storage body in the second high-temperature heat storage furnace. The high-temperature flue gas enters the coal-fired boiler. After the heat of the flue gas is fully utilized, it enters the dust collector and the desulfurization tower, and then enters the first fixed bed. CO2 in the flue gas reacts with CaO to generate CaCO3, and the flue gas after removing CO2 enters the waste heat recovery device;

[0032] Step 4: Open the valves between the CO2 storage tank and the CO2 booster fan, between the CO2 booster fan and the first high-temperature regenerative furnace, between the first high-temperature regenerative furnace and the first fixed bed, and at the outlet of the first fixed bed, draw CO2 from the CO2 storage tank, pressurize it with the CO2 booster fan, send it to the first high-temperature regenerative furnace for heating, and then enter the first fixed bed to heat the CaCO3 particles, and also decompose them into CO2 and CaO. Part of the CO2 is cooled by the CO2 cooler, and then pressurized by the CO2 booster equipment and sent to the CO2 storage tank. Part of the CO2 is cooled by the first CO2 cooler, and then pressurized by the CO2 booster fan and sent to the first high-temperature regenerative furnace for heating, and then the high-temperature CO2 is used to circulate and heat the CaCO3;

[0033] Step 5: After the system is running normally, the two regenerative furnaces operate alternately, one for heat storage and the other for heat release to heat CO2. The two fixed bed reactors also operate alternately, one for absorbing CO2 in the flue gas and the other for decomposing CaCO3 to generate CO2 and CaO, thereby achieving absorbent regeneration and carbon dioxide capture.

[0034] Furthermore, there is a preferred embodiment in which natural gas is used as fuel in the smoke gas generator during the startup phase, and when the system is operating normally, the fuel of the smoke gas generator can be replaced by coal or other fuels.

[0035] Furthermore, there is a preferred embodiment in which the above-mentioned carbon dioxide capture method is applicable to the capture of carbon dioxide in flue gas emitted by coal-fired power plants.

[0036] The beneficial effects of the present invention are:

[0037] 1. The solid calcium-based carbon dioxide capture system coupled with a coal-fired boiler provided by the present invention can efficiently capture CO2 and realize the regeneration of the solid calcium-based absorbent through fixed bed technology. Most of the heat of the high-temperature flue gas generated by the hot smoke generator is coupled with the coal-fired boiler, which not only promotes efficient energy recovery, but also significantly reduces the energy consumption of CO2 capture, providing an economically feasible strategy for achieving low-carbon goals.

[0038] 2. The present invention provides a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler, which is provided with an independent high-temperature flue gas generator to provide a heat source for decomposing CaCO3 into CaO and CO2.

[0039] 3. The present invention provides a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler, which uses a heat storage furnace to store part of the heat of the high-temperature flue gas in the flue gas generator in a heat storage body for heating CO2.

[0040] 4. The present invention provides a solid calcium-based carbon dioxide capture system coupled with a coal-fired boiler, which uses a fixed bed as a reactor for CO2 absorption and CaO regeneration, thereby ensuring that CO2 is in full contact with CaO powder and the reaction efficiency can be guaranteed.

[0041] 5. The present invention provides a solid calcium-based carbon dioxide capture system coupled with a coal-fired boiler, which uses high-temperature CO2 to heat CaCO3 without introducing other gas components, thereby ensuring that there are no other gases in the CO2 decomposed by CaCO3, and the purity of CO2 can be guaranteed.

[0042] 6. The present invention provides a solid calcium-based carbon dioxide capture system coupled with a coal-fired boiler, which uses high-temperature CO2 as part of the high-temperature CO2 at the outlet of the fixed bed as a heat source for decomposing CaCO3. Less heat is required for heating by a heat storage furnace, thereby reducing costs.

[0043] The technical solution provided by the present invention can realize the efficient capture of carbon dioxide in the flue gas discharged by coal-fired power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] 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.

[0045] Figure 1 It is a schematic diagram of a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler according to the present invention.

[0046] Among them, 1 represents a coal-fired boiler, 2 represents a dust collector, 3 represents a desulfurization tower, 4 represents a first fixed bed, 5 represents a second fixed bed, 6 represents a first high-temperature heat storage furnace, 7 represents a second high-temperature heat storage furnace, 8 represents a high-temperature flue gas generator, 9 represents a CO2 storage tank, 10 represents a waste heat recovery device, 11 represents a first CO2 cooler, 12 represents a CO2 booster fan, 13 represents a second CO2 cooler, 14 represents a CO2 booster device, and 15-28 and 30-31 represent valves. DETAILED DESCRIPTION

[0047] In the following description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0048] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0049] Embodiment 1: This embodiment provides a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler. The system uses a fixed bed as a reactor for absorbing CO2. The CO2 adsorbent uses solid CaO, which does not require the consumption of a large amount of water and can effectively avoid the problem of using liquid chemical reagents as CO2 adsorbents.

[0050] The system includes a high temperature flue gas generator 8, a high temperature heat storage furnace assembly, a fixed bed assembly, a CO2 storage assembly and a boiler assembly;

[0051] The high temperature flue gas generator 8 is used to provide high temperature flue gas for the high temperature regenerative furnace assembly;

[0052] The high temperature heat storage furnace assembly is used to provide heat to the fixed bed assembly and the boiler assembly respectively;

[0053] The fixed bed assembly is used to store CaCO3 particles, and after decomposing CO2 and CaO under the action of heat, the CO2 is sent to the CO2 storage assembly for storage. The CO2 storage assembly is used to provide heating energy for the high-temperature heat storage furnace assembly.

[0054] The boiler assembly is used to generate flue gas under the action of heat and send it to the fixed bed assembly to react with CaO to remove CO2 in the flue gas.

[0055] Implementation Method 2: See Figure 1 This embodiment is described. This embodiment specifically describes a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler as described in Embodiment 1;

[0056] The above-mentioned high temperature heat storage furnace assembly comprises a first high temperature heat storage furnace 6 and a second high temperature heat storage furnace 7;

[0057] The fixed bed assembly comprises a first fixed bed 4, a second fixed bed 5 and a waste heat recovery device 10;

[0058] The CO2 storage assembly includes a first CO2 cooler 11, a CO2 booster fan 12, a second CO2 cooler 13, a CO2 booster device 14 and a CO2 storage tank 9;

[0059] The boiler assembly comprises a coal-fired boiler 1, a dust collector 2 and a desulfurization tower 3;

[0060] like Figure 1 As shown, the specific structure of the carbon dioxide capture system is as follows:

[0061] The high-temperature flue gas generator 8 is connected to the first high-temperature regenerative furnace 6 and the second high-temperature regenerative furnace 7, respectively, to provide high-temperature flue gas, which heats the regenerative body in the high-temperature regenerative furnace. The first high-temperature regenerative furnace 6 is connected to the first fixed bed 4 and the coal-fired boiler 1, respectively; the second high-temperature regenerative furnace 7 is connected to the second fixed bed 5 and the coal-fired boiler 1, respectively; the two high-temperature regenerative furnaces can provide heat for the fixed bed, so that the solid CaCO3 particles in the fixed bed are decomposed into CO2 and CaO under the heat of the regenerative furnace; they can also provide heat for the coal-fired boiler 1. In actual application, the two high-temperature regenerative furnaces can be operated alternately, when one is used for heat storage, the other is used for heat release and heating of CO2. The two fixed-bed reactors are also operated alternately, one for absorbing CO2 in the flue gas, and the other for decomposing CaCO3 to generate CO2 and CaO, so as to realize absorbent regeneration and carbon dioxide capture.

[0062] The outlets of the first fixed bed 4 and the second fixed bed 5 are both connected to the first CO2 cooler 11 and the second CO2 cooler 13, so that the CO2 decomposed by the fixed bed can be cooled by the CO2 cooler. The second CO2 cooler 13 is connected to the CO2 storage tank 9 through the CO2 booster 14, so that the CO2 is pressurized by the CO2 booster and sent to the CO2 storage tank 9 for storage. The CO2 storage tank 9 is set to the inlet CO2 replenishment pipeline of the CO2 booster fan 12. At the same time, the first CO2 cooler 11 is connected to the CO2 booster fan 12, so that the cooled CO2 can be directly sent to the CO2 booster fan 12.

[0063] The coal-fired boiler 1 is connected to the dust collector 2 and the desulfurization tower 3 in sequence; the desulfurization tower 3 is connected to the first fixed bed 4 and the second fixed bed 5 respectively, and the outlets of the first fixed bed 4 and the second fixed bed 5 are connected to the waste heat recovery device 10 respectively; when the flue gas in the high-temperature heat storage furnace enters the coal-fired boiler 1, the flue gas heat is fully utilized and enters the dust collector 2 and the desulfurization tower 3 for treatment, and then the flue gas is sent to the first fixed bed 4 or the second fixed bed 5, and the CaO in the fixed bed reacts with the CO2 in the flue gas to generate CaCO3, and the flue gas after removing CO2 enters the waste heat recovery device 10, and finally, the clean flue gas without CO2 is discharged into the atmosphere.

[0064] Furthermore, the CO2 booster fan 12 is connected to the first high-temperature regenerative furnace 6 and the second high-temperature regenerative furnace 7 respectively, so that the CO2 decomposed by the fixed bed is used to heat the CaCO3 particles again without introducing other gas components, ensuring that there are no other gases in the CO2 decomposed by CaCO3, and the purity of CO2 can be guaranteed. It also makes it possible to use part of the high-temperature CO2 at the outlet of the fixed bed as the heat source for decomposing CaCO3, and less heat is required for heating by the regenerative furnace, thereby reducing costs.

[0065] The carbon dioxide capture system proposed in this embodiment adopts a fixed bed as a reactor for CO2 absorption and CaO regeneration, which can ensure that CO2 is fully in contact with CaO powder and the reaction efficiency can be guaranteed. At the same time, the system is equipped with an independent high-temperature flue gas generator to provide a heat source for the decomposition of CaCO3 into CaO and CO2. A heat storage furnace is used to store part of the heat of the high-temperature flue gas in the flue gas generator in the heat storage body for heating CO2.

[0066] Implementation method three, see Figure 1 The present embodiment is described as follows. On the basis of the above-mentioned embodiment, a plurality of valves are added to achieve carbon dioxide capture by controlling the opening of the valves.

[0067] like Figure 1 As shown, valves 15 and 16 are respectively arranged at the connection between the CO2 booster fan 12 and the first high-temperature regenerative furnace 6 and the second high-temperature regenerative furnace 7; valves 17 and 18 are respectively arranged at the connection between the high-temperature flue gas generator 8 and the first high-temperature regenerative furnace 6 and the second high-temperature regenerative furnace 7; valves 19 and 20 are respectively arranged at the connection between the first high-temperature regenerative furnace 6 and the second high-temperature regenerative furnace 7 and the coal-fired boiler 1; valve 21 is arranged between the first high-temperature regenerative furnace 6 and the first fixed bed 4, and valve 22 is arranged at the outlet of the first fixed bed 4. A valve 25 is provided; a valve 22 is provided between the second high-temperature heat storage furnace 7 and the second fixed bed 5, and a valve 26 is provided at the outlet of the second fixed bed 5; a valve 23 and a valve 24 are provided between the desulfurization tower 3 and the first fixed bed 4 and the second fixed bed 5 respectively; a valve 27 and a valve 28 are provided between the first fixed bed 4, the second fixed bed 5 and the waste heat recovery device respectively; a valve 30 is provided between the CO2 boosting equipment 14 and the CO2 storage tank 9; a valve 31 is provided between the CO2 storage tank 9 and the CO2 boosting fan 12.

[0068] Embodiment 4: This embodiment provides a carbon dioxide capture method implemented by a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler based on any one of the above embodiments, and the method specifically comprises the following steps:

[0069] Step 1: Add solid CaCO3 particles into the first fixed bed and the second fixed bed respectively, and close all valves.

[0070] Step 2: Open the valves between the high-temperature flue gas generator and the first high-temperature regenerative furnace, between the first high-temperature regenerative furnace and the first fixed bed, at the outlet of the first fixed bed, and between the CO2 booster and the CO2 storage tank, start the high-temperature flue gas generator, and heat the regenerative body in the first high-temperature regenerative furnace with the high-temperature flue gas. At the same time, use the high-temperature flue gas to heat the CaCO3 particles in the first fixed bed to decompose them into CO2 and CaO. The CO2 is first cooled by the second CO2 cooler, and then pressurized by the CO2 booster and stored in the CO2 storage tank.

[0071] Step 3: Close the valves between the first high-temperature heat storage furnace and the first fixed bed and at the outlet of the first fixed bed, open the valves between the high-temperature flue gas generator and the second high-temperature heat storage furnace, between the second high-temperature heat storage furnace and the coal-fired boiler, between the desulfurization tower and the first fixed bed, and between the first fixed bed and the waste heat recovery device, start the high-temperature flue gas generator, and the high-temperature flue gas heats the heat storage body in the second high-temperature heat storage furnace. The high-temperature flue gas enters the coal-fired boiler. After the heat of the flue gas is fully utilized, it enters the dust collector and the desulfurization tower, and then enters the first fixed bed. CO2 in the flue gas reacts with CaO to generate CaCO3, and the flue gas after removing CO2 enters the waste heat recovery device;

[0072] Step 4: Open the valves between the CO2 storage tank and the CO2 booster fan, between the CO2 booster fan and the first high-temperature regenerative furnace, between the first high-temperature regenerative furnace and the first fixed bed, and at the outlet of the first fixed bed. Draw CO2 from the CO2 storage tank, pressurize it with the CO2 booster fan, and send it to the first high-temperature regenerative furnace for heating. Then, it enters the first fixed bed to heat the CaCO3 particles, and also decomposes them into CO2 and CaO. Part of the CO2 is cooled by the CO2 cooler, and then pressurized by the CO2 booster equipment and sent to the CO2 storage tank. Part of the CO2 is sent to the CO2 storage tank. O2 After being cooled by the first CO2 cooler, it is then pressurized by the CO2 booster fan and sent to the first high-temperature regenerative furnace for heating. The high-temperature CO2 is then used to circulate and heat CaCO3 to ensure the decomposition efficiency of CaCO3.

[0073] Step 5: After the system is running normally, the two regenerative furnaces operate alternately, one for heat storage and the other for heat release to heat CO2. The two fixed bed reactors also operate alternately, one for absorbing CO2 in the flue gas and the other for decomposing CaCO3 to generate CO2 and CaO, thereby achieving absorbent regeneration and carbon dioxide capture.

[0074] In practical application, this implementation method is specifically as follows:

[0075] In order to prevent other gases from being introduced into the flue gas used for decomposing CaCO3, natural gas is used as fuel in the flue gas generator 8 during the startup phase. When the system is operating normally, the fuel of the flue gas generator 8 can be replaced by coal or other fuels.

[0076] Step 1: Add sufficient solid CaCO3 particles to the first fixed bed 4 and the second fixed bed 5 respectively, and keep all valves in the system closed. Open valves 18, 22, 26 and 30, start the high-temperature flue gas generator 8, and use the high-temperature flue gas to heat the heat storage body in the second high-temperature heat storage furnace 7. At the same time, use the high-temperature flue gas to heat the CaCO3 particles in the second fixed bed 5 to decompose them into CO2 and CaO. The CO2 is first cooled by the CO2 cooler 13, and then pressurized by the CO2 boosting equipment and stored in the CO2 storage tank 9. The CO2 storage tank 9 is set to the CO2 replenishment pipeline at the inlet of the CO2 booster fan.

[0077] Step 2: Close valve 18, valve 22, valve 26; open valve 16, valve 19, valve 24 and valve 28; start the high-temperature flue gas generator, and the high-temperature flue gas generated is used to heat the heat storage body in the first high-temperature heat storage furnace 6, and then the flue gas enters the coal-fired boiler 1. After the flue gas heat is fully utilized, it enters the dust collector 2 and the desulfurization tower 3. The flue gas passes through the second fixed bed 5, and the CO2 in the flue gas reacts with CaO to generate CaCO3. The flue gas after removing CO2 enters the waste heat recovery device 10. Finally, the clean flue gas without CO2 is discharged into the atmosphere.

[0078] Step 3: At the same time, open valves 15, 21, 25 and 31, draw CO2 from the CO2 storage tank 9, pressurize it with the CO2 booster fan 12, and send it to the first high-temperature regenerative furnace 6 for heating, and then enter the first fixed bed 4 to heat the CaCO3 particles, and also decompose them into CO2 and CaO. A part of the CO2 is cooled by the CO2 cooler 13, and then pressurized by the CO2 booster device 14 and sent to the CO2 storage tank 9. A part of the CO2 is cooled by the CO2 cooler 11, and then pressurized by the CO2 booster fan 12 and sent to the first high-temperature regenerative furnace 6 for heating, and then the high-temperature CO2 is used to heat the CaCO3 in a cycle to ensure the decomposition efficiency of CaCO3.

[0079] Step 4: When the system is running normally, the two regenerative furnaces are operated alternately, one for heat storage and the other for heat release and heating of CO2. The two fixed bed reactors are also operated alternately, one for absorbing CO2 in the flue gas and the other for decomposing CaCO3 to generate CO2 and CaO, realizing absorbent regeneration and carbon dioxide capture.

[0080] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0081] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0082] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0083] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0084] The above description is only the implementation mode of the present invention and is not limited to the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler, characterized in that: It includes a high-temperature flue gas generator (8), a high-temperature heat storage furnace assembly, a fixed bed assembly, a CO2 storage assembly and a boiler assembly; The high temperature flue gas generator (8) is used to provide high temperature flue gas for the high temperature regenerative furnace assembly; The high temperature heat storage furnace assembly is used to provide heat to the fixed bed assembly and the boiler assembly respectively; The fixed bed assembly is used to store CaCO3 particles, and after decomposing CO2 and CaO under the action of heat, the CO2 is sent to the CO2 storage assembly for storage. The CO2 storage assembly is used to provide heating energy for the high-temperature heat storage furnace assembly. The boiler assembly is used to generate flue gas under the action of heat and send it to the fixed bed assembly to react with CaO to remove CO2 in the flue gas.

2. A solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler according to claim 1, characterized in that: The high temperature heat storage furnace assembly comprises a first high temperature heat storage furnace (6) and a second high temperature heat storage furnace (7); The fixed bed assembly comprises a first fixed bed (4), a second fixed bed (5) and a waste heat recovery device (10); The first fixed bed (4) and the second fixed bed (5) are both connected to a waste heat recovery device (10); The first fixed bed (4) is connected to a first high-temperature heat storage furnace (6), and the second fixed bed (5) is connected to a second high-temperature heat storage furnace (7).

3. A solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler according to claim 2, characterized in that: The CO2 storage assembly comprises a first CO2 cooler (11), a CO2 booster fan (12), a second CO2 cooler (13), a CO2 booster device (14) and a CO2 storage tank (9); The first CO2 cooler (11) and the second CO2 cooler (13) are both connected to the fixed bed assembly; The second CO2 cooler (13) is connected to the CO2 storage tank (9) via the CO2 pressurizing device (14); The CO2 storage tank (9) and the first CO2 cooler (11) are both connected to the CO2 booster fan (12); The CO2 booster fan (12) is connected to the first high-temperature heat storage furnace (6) and the second high-temperature heat storage furnace (7) respectively.

4. A solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler according to claim 3, characterized in that: The boiler assembly comprises a coal-fired boiler (1), a dust collector (2) and a desulfurization tower (3); The coal-fired boiler (1) is used to generate flue gas under the action of heat and send it to the dust collector (2); The dust collector (2) removes dust from the flue gas and sends it to the desulfurization tower (3) for desulfurization treatment; The desulfurization tower (3) sends the flue gas after desulfurization to the fixed bed assembly.

5. A solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler according to claim 4, characterized in that: The system is also equipped with multiple valves.

6. A solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler according to claim 5, characterized in that: Carbon dioxide is captured by opening and closing multiple valves.

7. A solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler according to claim 5, characterized in that: The opening and closing of multiple valves are achieved through the control system.

8. A method for capturing carbon dioxide using a solid calcium-based carbon dioxide capture system coupled to a coal-fired boiler as claimed in any one of claims 1 to 7, characterized in that: The method is: Step 1: Add solid CaCO3 particles into the first fixed bed and the second fixed bed respectively, and close all valves; Step 2: Open the valves between the high-temperature flue gas generator and the first high-temperature regenerative furnace, between the first high-temperature regenerative furnace and the first fixed bed, at the outlet of the first fixed bed, and between the CO2 booster and the CO2 storage tank, start the high-temperature flue gas generator, and heat the regenerative body in the first high-temperature regenerative furnace with the high-temperature flue gas. At the same time, use the high-temperature flue gas to heat the CaCO3 particles in the first fixed bed to decompose them into CO2 and CaO. The CO2 is first cooled by the second CO2 cooler, and then pressurized by the CO2 booster and stored in the CO2 storage tank. Step 3: Close the valves between the first high-temperature heat storage furnace and the first fixed bed and at the outlet of the first fixed bed, open the valves between the high-temperature flue gas generator and the second high-temperature heat storage furnace, between the second high-temperature heat storage furnace and the coal-fired boiler, between the desulfurization tower and the first fixed bed, and between the first fixed bed and the waste heat recovery device, start the high-temperature flue gas generator, and the high-temperature flue gas heats the heat storage body in the second high-temperature heat storage furnace. The high-temperature flue gas enters the coal-fired boiler. After the heat of the flue gas is fully utilized, it enters the dust collector and the desulfurization tower, and then enters the first fixed bed. CO2 in the flue gas reacts with CaO to generate CaCO3, and the flue gas after removing CO2 enters the waste heat recovery device; Step 4: Open the valves between the CO2 storage tank and the CO2 booster fan, between the CO2 booster fan and the first high-temperature regenerative furnace, between the first high-temperature regenerative furnace and the first fixed bed, and at the outlet of the first fixed bed, draw CO2 from the CO2 storage tank, pressurize it with the CO2 booster fan, send it to the first high-temperature regenerative furnace for heating, and then enter the first fixed bed to heat the CaCO3 particles, and also decompose them into CO2 and CaO. Part of the CO2 is cooled by the CO2 cooler, and then pressurized by the CO2 booster equipment and sent to the CO2 storage tank. Part of the CO2 is cooled by the first CO2 cooler, and then pressurized by the CO2 booster fan and sent to the first high-temperature regenerative furnace for heating, and then the high-temperature CO2 is used to circulate and heat the CaCO3; Step 5: After the system is running normally, the two regenerative furnaces operate alternately, one for heat storage and the other for heat release to heat CO2. The two fixed bed reactors also operate alternately, one for absorbing CO2 in the flue gas and the other for decomposing CaCO3 to generate CO2 and CaO, thereby achieving absorbent regeneration and carbon dioxide capture.

9. A solid calcium-based carbon dioxide capture method coupled with a coal-fired boiler according to claim 8, characterized in that: During the startup phase, natural gas is used as fuel in the flue gas generator. When the system is running normally, the fuel of the flue gas generator can be replaced by coal or other fuels.

10. A solid calcium-based carbon dioxide capture method coupled with a coal-fired boiler according to claim 8, characterized in that: This method is applicable to the capture of carbon dioxide in flue gas emitted by coal-fired power plants.

Images