Coal-fired power plant carbon dioxide capture system and heat energy utilization method

Abstract

The present application relates to a kind of coal-fired power plant carbon dioxide capture system and heat energy utilization method, including wet desulfurization equipment, carbonation reaction equipment, calcination reaction equipment and carbon dioxide collection equipment;The flue gas output end of the wet desulfurization equipment, the carbonation reaction equipment, the calcination reaction equipment and carbon dioxide collection equipment are sequentially communicated to form carbon dioxide capture passage;The calcination reaction equipment has solid-state material recovery part;The flue gas output end of the wet desulfurization equipment sequentially communicates the input end of the solid-state material recovery part, the carbonation reaction equipment by first pipeline component, to form the raw material first supply branch of the carbonation reaction equipment;The flue gas output end of the wet desulfurization equipment also communicates the input end of the carbonation reaction equipment by second pipeline component, to form the raw material second supply branch of the carbonation reaction equipment, with the advantage of sufficiently absorbing carbon dioxide in flue gas to reduce system carbon emission.

Description

[0001] This application is the following patent application:

[0002] Application Number: CN202410867701.9

[0003] Application Title: A Carbon Dioxide Capture System and Method for Coal-fired Power Plants

[0004] Application date: 2024-07-01

[0005] The application for a divisional case. Technical Field

[0006] This invention relates to the technical field of carbon dioxide capture, and in particular to a carbon dioxide capture system and heat energy utilization method for a coal-fired power plant. Background Technology

[0007] Current methods for capturing carbon dioxide from flue gas in coal-fired power plants primarily rely on calcium-based adsorbents for carbonation and calcination-based CO2 adsorption using calcium cycle technology. However, this technology has certain drawbacks. For example, while the carbon dioxide capture effect is better (i.e., the carbonation reaction efficiency is high) at an acidification reaction temperature of 600–650°C, most carbonation reactors lack corresponding temperature control measures. Furthermore, the carbonation reaction (CaO + CO2 → CaCO3) is exothermic. When heated with auxiliary heating equipment, it can easily increase system power consumption and lead to excessively high carbonation reaction temperatures, thus affecting the carbonation reaction efficiency and failing to meet the required reaction temperature of 600–650°C.

[0008] Therefore, providing a carbon dioxide capture system and method for coal-fired power plants to fully absorb carbon dioxide from flue gas is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a carbon dioxide capture system and a method for heat energy utilization in a coal-fired power plant.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A carbon dioxide capture system for a coal-fired power plant includes a wet desulfurization unit, a carbonation reaction unit, a calcination reaction unit, and a carbon dioxide collection unit. The flue gas output end of the wet desulfurization unit, the carbonation reaction unit, the calcination reaction unit, and the carbon dioxide collection unit are sequentially connected to form a carbon dioxide capture pathway. The calcination reaction unit has a solids recovery section. The flue gas output end of the wet desulfurization unit is sequentially connected to the solids recovery section and the input end of the carbonation reaction unit through a first pipeline assembly to form a first feedstock supply branch for the carbonation reaction unit. The flue gas output end of the wet desulfurization unit is also connected to the input end of the carbonation reaction unit through a second pipeline assembly to form a second feedstock supply branch for the carbonation reaction unit.

[0012] Preferably, the first piping assembly includes a first pipe, the output port of which is located on the side away from the output end of the carbonation reaction device; the second piping assembly includes a second pipe and a plurality of branch pipes connected to the output end of the second pipe; the output ports of the plurality of branch pipes are arranged and distributed along the direction from the output end of the first pipe to the output end of the carbonation reaction device.

[0013] Preferably, the first piping assembly further includes a first regulating valve located on the first pipe, and the second piping assembly further includes a second regulating valve located on the second pipe; and / or, the first piping assembly further includes a first regulating valve located on the first pipe, and the second piping assembly further includes a third regulating valve located on the branch pipe.

[0014] Preferably, it further includes a flue gas preheating supply pipeline; the input end of the flue gas preheating supply pipeline is connected to the flue gas output end of the wet desulfurization equipment, and the output end of the flue gas preheating supply pipeline is connected to the input end of the first pipeline assembly and the input end of the second pipeline assembly.

[0015] Preferably, it further includes a solid-gas separation device for separating the solid and gaseous substances output from the carbonation reaction equipment; the input end of the solid-gas separation device is connected to the output end of the carbonation reaction equipment, and the solid output end of the solid-gas separation device is connected to the input end of the calcination reaction equipment.

[0016] Preferably, the gaseous output end of the solid-gas separation device is connected to the flue gas output end of the wet desulfurization equipment, and / or, the solid output end of the solid-gas separation device is also connected to the input end of the wet desulfurization equipment.

[0017] Preferably, the system further includes a flue gas preheating supply pipeline, which includes a flue gas preheater for preheating the flue gas output from the wet desulfurization equipment; it also includes a solid-gas separation device, which includes a second heat exchanger for cooling the gaseous substances output from the carbonation reaction equipment; the carbon dioxide collection device includes a first heat exchanger for cooling the carbon dioxide to be stored; the second heat exchanger, the first heat exchanger, and the flue gas preheater are connected in sequence, and the input end of the second heat exchanger and the output end of the flue gas preheater are both connected to the condensate system of the coal-fired power plant, so that the second heat exchanger, the first heat exchanger, and the flue gas preheater all exchange heat with the condensate system of the coal-fired power plant.

[0018] Preferably, the wet desulfurization equipment includes a desulfurizing agent supply tank; the input end of the calcination reaction equipment is also connected to the desulfurizing agent supply tank.

[0019] A carbon dioxide capture method based on the aforementioned carbon dioxide capture system in a coal-fired power plant includes the following steps: inputting flue gas discharged from a wet desulfurization device into a carbonation reaction device for carbonation reaction to generate a solid; calcining the solid using a calcination reaction device to generate carbon dioxide and a carbon dioxide capture absorbent; collecting the carbon dioxide using a carbon dioxide collection device; using a first pipeline assembly to transport the flue gas discharged from the wet desulfurization device to the carbonation reaction device, and using the flue gas flowing through the first pipeline assembly to transport the carbon dioxide capture absorbent generated by the calcination reaction device to the carbonation reaction device; and using a second pipeline assembly to transport the flue gas discharged from the wet desulfurization device to the carbonation reaction device.

[0020] Preferably, the method further includes the following steps: using the second pipeline assembly to transport the flue gas discharged from the wet desulfurization equipment in layers to the carbonation reaction equipment; and / or, adjusting the flow rate of the flue gas transported by the first pipeline assembly and the second pipeline assembly; and / or, preheating the flue gas discharged from the wet desulfurization equipment and supplying the heated flue gas to the first pipeline assembly and the second pipeline assembly.

[0021] Preferably, the method further includes the following steps: using a solid-gas separation device to separate the solid and gaseous substances output from the output end of the carbonation reaction equipment; and / or, transporting the desulfurizing agent from the wet desulfurization equipment to the calcination reaction equipment for calcination to generate carbon dioxide and a carbon dioxide capture and absorbent.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The carbon dioxide capture system for a coal-fired power plant provided in the above technical solution, through the coordinated arrangement of a carbonation reaction device, a first pipeline assembly, a second pipeline assembly, and a solids recovery unit, enables the carbonation reaction device to have a first supply branch and a second supply branch for raw materials. The first supply branch supplies the carbon dioxide collecting absorbent generated by the calcination reaction device to the carbonation reaction device, while the second supply branch supplies flue gas to the carbonation reaction device. On the one hand, this reduces the input of carbon dioxide collecting absorbent raw materials and reuses the heat energy in the carbon dioxide collecting absorbent, reducing unit energy consumption and avoiding energy waste. On the other hand, by balancing the temperature of the carbon dioxide collecting absorbent and the flue gas temperature in the first supply branch, and by supplying flue gas from the second supply branch, the temperature in the carbonation reaction device can be controlled, preventing the carbonation reaction efficiency from decreasing due to excessively high or low carbonation reaction temperatures. Meanwhile, the carbon dioxide capture method based on the above system provided in this solution supplies flue gas to the carbonation reaction equipment and high-temperature carbon dioxide collection and absorption agent generated in the calcination reaction equipment (solid matter recovery section) through the first pipeline assembly, and supplies flue gas to the carbonation reaction equipment through the second pipeline assembly. This can not only achieve temperature control in the carbonation reaction equipment, but also reduce the system energy and input of carbon dioxide collection and absorption agent raw materials. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the first embodiment of the system of the present invention.

[0026] Figure 2 for Figure 1 A schematic diagram showing the connection between the carbonation reaction equipment and the first and second pipeline assemblies.

[0027] Figure 3 for Figure 1 A schematic diagram of one example of a calcination reaction device.

[0028] Figure 4 This is a schematic diagram of a second embodiment of the system of the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Wet desulfurization equipment; 2. Carbonation reaction equipment; 3. Calcination reaction equipment; 31. Solid waste recovery section; 32. Preheating section; 33. Reaction section; 34. Temperature control components; 341. Temperature monitor; 342. Electromagnetic heating controller; 4. Carbon dioxide collection equipment; 41. First heat exchanger; 42. First bag filter; 43. Vacuum pump; 44. Compressor; 45. Carbon dioxide storage tank; 5. First pipeline assembly; 50. First pipe; 500. First regulating valve; 6. Second pipeline assembly; 60. Two pipes; 600, Second regulating valve; 61, Branch pipe; 610, Third regulating valve; 7, Flue gas preheating supply pipeline; 71, Exhaust fan; 72, Flue gas preheater; 8, Solid-gas separation device; 81, Cyclone separator; 82, Second heat exchanger; 83, Second bag filter; 100, Primary high-temperature heater; 200, Secondary high-temperature heater; 300, Tertiary high-temperature heater; 400, Branch pipeline; 401, Control valve; 700, Unit induced draft fan; 800, Unit dust collector; 900, Coal-fired boiler. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly 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 of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] Calcium cycle technology based on calcium-based adsorbents for carbonation / calcination to adsorb CO2 can be used for post-combustion CO2 capture technology in CCUS. It mainly uses calcium-based adsorbents to capture CO2 from the exhaust gas of existing coal-fired power plant combustion equipment, thereby reducing the CO2 emissions of the system. It is one of the CO2 capture technologies that mainstream research institutions are optimistic about.

[0035] However, this technology still has many problems.

[0036] Firstly, in order to improve the cyclic CO2 capture activity of calcium-based adsorbents, calcium-based materials have been screened, and a large number of adsorbent modification methods have been proposed. For example, methods such as calcining organic calcium-based materials, synthesizing nanoparticles, adding high-melting-point frameworks, high-temperature steam thermal activation, alkali metal salt modification, and conversion of calcium-containing solid waste have been proposed. However, these methods are cumbersome and the preparation cost of the adsorbent is extremely high.

[0037] Secondly, most carbonation reactors lack temperature control measures. The carbonation reaction CaO + CO2 = CaCO3 is an exothermic reaction with a temperature window of 600–650°C. Without cooling measures, the carbonation reactor will overheat, resulting in a decrease in carbonation reaction efficiency.

[0038] Finally, in most calcium cycle carbon dioxide capture methods, the carbon dioxide captured by the calcination reaction has low purity and cannot meet the standards for industrial-grade carbon dioxide use.

[0039] This invention addresses the aforementioned problems and, considering the existing flue gas, material, and energy conditions of coal-fired power plants, proposes a carbon dioxide capture system and method for coal-fired power plants. This system effectively adsorbs carbon dioxide from the tail gas of coal-fired power plants, yielding high-purity carbon dioxide. The specific solution is as follows:

[0040] Example 1

[0041] See Figures 1 to 3 This invention provides a carbon dioxide capture system for a coal-fired power plant, including a wet desulfurization device 1, a carbonation reaction device 2, a calcination reaction device 3, and a carbon dioxide collection device 4. The flue gas output end of the wet desulfurization device 1, the carbonation reaction device 2, the calcination reaction device 3, and the carbon dioxide collection device 4 are connected in sequence to form a carbon dioxide capture path.

[0042] Specifically, the flue gas discharged from the wet desulfurization unit 1 is transported to the carbonation reaction unit 2, where it reacts with the carbon dioxide capture and absorbent to produce a solid (carbonate). This solid then absorbs the carbon dioxide in the flue gas. The solid (carbonate) produced in the carbonation reaction unit 2 is then fed into the calcination reaction unit 3 for calcination, producing carbon dioxide and another carbon dioxide capture and absorbent. It is known that any unreacted flue gas in the carbonation reaction unit 2 will separate from the solid and will not enter the calcination reaction unit 3. Only the solid enters the calcination reaction unit 3. The carbon dioxide produced after calcination of the solid is of relatively high purity and can be recycled.

[0043] Various carbon dioxide capture and absorbents can be used, such as Li4SiO4, magnesium oxide, and hydrotalcite. In this embodiment, calcium oxide (CaO) can be used as the carbon dioxide capture and absorbent.

[0044] The reaction that occurs in carbonation reactor 2 is: CaO + CO2 → CaCO3;

[0045] The reaction that occurs in calcination reaction equipment 3 is: CaCO3 → CaO + CO2.

[0046] In this way, on the one hand, carbon dioxide in the flue gas discharged from the wet desulfurization equipment 1 can be extracted and collected for utilization; on the other hand, carbon emissions from the wet desulfurization equipment 1 can be reduced.

[0047] Since the CaO generated by the calcination reaction device 3 has a high temperature, generally around 900-950℃, and can be used as a carbon dioxide collection and absorption agent, while the flue gas temperature output by the wet desulfurization device 1 is usually around 50℃, when the CaO generated in the calcination reaction device 3 is supplied to the carbonation reaction device 2, it can be used as a raw material (carbon dioxide collection and absorption agent) for the carbonation reaction device 2, and can also raise the temperature of the carbonation reaction device 2, increasing the reaction efficiency and effect of the carbonation reaction device 2. Therefore, in this embodiment, the calcination reaction device 3 has a solid recovery unit 31; the flue gas output end of the wet desulfurization device 1 is connected to the solid recovery unit 31 and the input end of the carbonation reaction device 2 in sequence through the first pipeline assembly 5 to form the first raw material supply branch of the carbonation reaction device 2; the flue gas output end of the wet desulfurization device 1 is also connected to the input end of the carbonation reaction device 2 through the second pipeline assembly 6 to form the second raw material supply branch of the carbonation reaction device 2. It is understood that in this embodiment, the solid matter recovery unit 31 is configured as a recovery hopper, and the output end of the recovery hopper is connected to the first pipeline assembly 5. In addition, the amount of CaO transported by the recovery hopper can be controlled by a valve. Of course, in other embodiments, the solid matter recovery unit 31 can also be directly configured as a pipeline whose output end is connected to the first pipeline assembly 5, that is, the solid matter recovery unit 31 can be connected to the calcination reaction equipment 3 and the first pipeline assembly 5.

[0048] Through the above scheme, the coordinated arrangement of the carbonation reaction equipment 2, the first pipeline assembly 5, the second pipeline assembly 6, and the solid recovery unit 31 enables the carbonation reaction equipment 2 to have a first supply branch and a second supply branch for raw materials. The first supply branch can supply CaO generated by the calcination reaction equipment 3 to the carbonation reaction equipment 2, and the second supply branch can supply flue gas to the carbonation reaction equipment 2. On the one hand, it can reduce the input of CaO raw materials and reuse the heat energy in CaO, thereby reducing unit energy consumption and avoiding energy waste. On the other hand, by balancing the CaO temperature and the flue gas temperature in the first supply branch and supplying flue gas from the second supply branch, the temperature in the carbonation reaction equipment 2 can be controlled, avoiding the carbonation reaction efficiency from being reduced due to excessively high or low carbonation reaction temperatures.

[0049] In order to improve the temperature control effect of the carbonation reaction equipment 2, in this embodiment, the first pipeline assembly 5 includes a first pipe 50, the output port of the first pipe 50 is located on the side away from the output end of the carbonation reaction equipment 2; the second pipeline assembly 6 includes a second pipe 60 and a plurality of branch pipes 61 connected to the output end of the second pipe 60; the output ports of the plurality of branch pipes 61 are arranged and distributed along the direction from the output end of the first pipe 50 to the output end of the carbonation reaction equipment 2.

[0050] Specifically, see Figure 2Along the axial direction of the carbonation reaction device 2, the output port of the first pipe 50 is directly opposite the output end of the carbonation reaction device 2, that is, the direction of the flue gas and CaO supplied by the first pipe 50 is the axial direction of the carbonation reaction device 2 (e.g., Figure 2 (As shown in the Z direction); the branch pipes 61 are distributed in three layers along the axial direction of the carbonation reaction device 2, with four branch pipes 61 corresponding to each layer. This allows the air in the second pipe 60 to be stratified and evenly supplied to the carbonation reaction device 2, enabling more uniform mixing of flue gas and CaO, thereby increasing reaction efficiency. Furthermore, the flue gas delivery direction of the branch pipes 61 (e.g., in the Z direction) Figure 2 The X1 and X2 directions shown are perpendicular to the direction of flue gas and CaO supply from the first pipe 50, so that when the branch pipe 61 supplies flue gas, it can generate a certain resistance to the flue gas and CaO supplied from the first pipe 50, increase the mixing reaction time of CaO and flue gas, and make the mixing effect between the two better.

[0051] Furthermore, the output port of branch pipe 61 adopts the Pitot tube design principle, which is conducive to increasing the airflow disturbance inside the carbonation reaction equipment 2, increasing the mass and heat transfer intensity, and further increasing the mixing reaction effect of CaO and flue gas.

[0052] Of course, in other embodiments, the branch pipes 61 may also be provided in two, four, or more layers, with two, three, or more pipes distributed in each layer, depending on the actual situation (such as the axial length and cross-sectional dimensions of the carbonation reaction equipment 2). Furthermore, in other embodiments, the direction of the flue gas output from the output port of the branch pipe 61 may not be perpendicular to the flue gas and CaO conveying direction; it may be at a certain angle, preferably towards the output port side of the first pipe 50. In other embodiments, the output ports of the branch pipes 61 in the same layer are also staggered.

[0053] See Figure 1 and Figure 2 To achieve precise control of the flue gas within the first pipe 50 and the second pipe 60, and to maintain the internal temperature of the carbonation reaction equipment 2 within the reaction window of 600–650°C, in this embodiment, the first piping assembly 5 further includes a first regulating valve 500 located on the first pipe 50, and the second piping assembly 6 further includes a second regulating valve 600 located on the second pipe 60. This allows for control of the amount of flue gas entering the first pipe 50 and the second pipe 60 by adjusting the opening degrees of the first regulating valve 500 and the second regulating valve 600. Preferably, in this embodiment, the amount of flue gas in the first pipe 50 can be adjusted to account for 10–20% of the total flue gas volume, and the amount of flue gas in the second pipe 60 can be adjusted to account for 80–90% of the total flue gas volume.

[0054] Furthermore, to achieve precise control of the airflow in each branch pipe 61 and avoid local overheating or underheating inside the carbonation reaction equipment 2, so that the interior of the carbonation reaction equipment 2 can be uniformly maintained at a reaction window temperature of 600-650°C, in this embodiment, the second pipeline assembly 6 also includes a third regulating valve 610 located on the branch pipe 61, thereby controlling the amount of flue gas entering each layer of the carbonation reaction equipment 2. Preferably, in this embodiment, from the output end of the carbonation reaction equipment 2 to the output end of the first pipe 50, the flue gas delivered by the three branch pipes 61 accounts for 30%, 40%, and 30% of the total flue gas entering the second pipe 60, respectively.

[0055] Of course, in other embodiments, only the third regulating valve 610 may be provided in both the second regulating valve 600 and the third regulating valve 610.

[0056] Since the temperature of the flue gas in the wet desulfurization equipment 1 is usually around 50°C, in order to avoid the flue gas temperature being too low or too high and affecting the temperature control of the carbonation reaction equipment 2, this embodiment also includes a flue gas preheating supply pipeline 7. The input end of the flue gas preheating supply pipeline 7 is connected to the flue gas output end of the wet desulfurization equipment 1, and the output end of the flue gas preheating supply pipeline 7 is connected to the input ends of the first pipeline assembly 5 and the second pipeline assembly 6. Thus, the flue gas temperature can be flexibly controlled between 50°C and 140°C according to changes in operating conditions.

[0057] Because unreacted flue gas may exist in carbonation reaction equipment 2, in order to collect high-purity carbon dioxide, see [reference needed]. Figure 1 In this embodiment, the system further includes a solid-gas separation device 8, which is used to separate the solid and gaseous substances output from the carbonation reaction device 2. The input end of the solid-gas separation device 8 is connected to the output end of the carbonation reaction device 2, and the solid output end of the solid-gas separation device 8 is connected to the input end of the calcination reaction device 3.

[0058] Furthermore, in order to further reduce the carbon emissions of this system, the gaseous output end of the solid-gas separation device 8 is connected to the wet desulfurization equipment 1, and the unreacted flue gas can be transported again to the carbonation reaction equipment 2 through the flue gas output end of the wet desulfurization equipment 1.

[0059] In existing coal-fired power plants, the flue gas generated by the coal-fired boiler 900 is typically dedusted by the unit dust collector 800 before being fed into the wet desulfurization equipment 1 via the unit induced draft fan 700. To reduce system construction costs, the unreacted flue gas can be directly transported to the wet desulfurization equipment 1 using the unit induced draft fan 700, i.e., the gaseous output end of the solid-gas separation device 8 is connected to the input end of the unit induced draft fan 700. Alternatively, in other embodiments, the gaseous output end of the solid-gas separation device 8 is connected to the flue gas output end of the wet desulfurization equipment 1, and the unreacted flue gas is directly guided to the flue gas output end of the wet desulfurization equipment 1, or the output ends of the first pipeline assembly 5 and the second pipeline assembly 6, using the power of the induced draft fan 71.

[0060] As the number of reaction cycles increases, some calcium carbonate will sinter and fail. In this embodiment, the solid output end of the solid-gas separation device 8 is also connected to the input end of the wet desulfurization equipment 1, so that the failed calcium carbonate can be transported to the wet desulfurization equipment 1 for reuse.

[0061] Furthermore, the CaO in the carbonation reaction device 2 can come from various sources, as long as it can be transported to the carbonation reaction device 2 and react with carbon dioxide in the flue gas.

[0062] In this embodiment, the wet desulfurization equipment 1 includes a desulfurizing agent supply tank; the input end of the calcination reaction equipment 3 is also connected to the desulfurizing agent supply tank, thereby enabling the use of existing tanks in the existing unit to provide raw material sources for this system, saving the construction cost of the system.

[0063] Furthermore, in this embodiment, the desulfurizing agent (CaCO3) of the wet desulfurization equipment 1 is transported to the calcination reaction equipment 3 for calcination, and the CaO generated after calcination is supplied to the carbonation reaction equipment 2 through the first pipeline assembly 5.

[0064] The calcination reaction device 3 can be configured in various ways to calcine the solids generated by the carbonation reaction device 2 to produce carbon dioxide and carbon dioxide capture and absorbent. The carbon dioxide collection device 4 can also be configured in various ways to collect the carbon dioxide generated by the calcination reaction device 3. The flue gas preheating supply pipeline 7 can also be configured in various ways to preheat the flue gas at the output end of the wet desulfurization device 1. The solid-gas separation device 8 can also be configured in various ways to separate the gaseous and solid substances output from the output end of the carbonation reaction device 2.

[0065] See Figure 1 and Figure 3In this embodiment, the calcination reaction equipment 3 adopts an electromagnetically heated rotary kiln. Electromagnetic heating technology is used to provide a heat source, enabling the calcination reaction equipment 3 to reach a reaction window temperature of 900–950°C, causing calcium carbonate to decompose into carbon dioxide and calcium oxide. Specifically, the electromagnetically heated rotary kiln employs a two-stage electromagnetic heating coil (i.e., an electromagnetic heating coil wound twice around the outer wall of the rotary kiln). One stage is a preheating section 32, and the other is a reaction section 33. The preheating section 32 heats the calcium carbonate powder input into the calcination reaction equipment 3 from room temperature to 600–800°C, thus avoiding direct contact between the calcium carbonate and the ultra-high temperature heat source, which would cause the calcium carbonate to be hot on the outside and cold on the inside, resulting in incomplete sintering. The temperature of the reaction section 33 is maintained at 900–950°C, promoting the decomposition of calcium carbonate into carbon dioxide and calcium oxide.

[0066] Furthermore, in order to achieve precise temperature control of the preheating section 32 and the reaction section 33, the calcination reaction equipment 3 also includes a temperature control component 34. The temperature control component 34 includes a temperature monitor 341 and an electromagnetic heating controller 342. The temperature monitor 341 and the electromagnetic heating controller 342 are electrically connected. The temperature monitor 341 is used to detect the temperature of the preheating section 32 and the reaction section 33 in real time and feed it back to the electromagnetic heating controller 342. The electromagnetic heating controller 342 is used to control the current and voltage changes of the heating coil according to the temperature detected by the temperature monitor 341, thereby controlling the temperature of the electromagnetic heating coil and adjusting the temperature of the preheating section 32 and the reaction section 33.

[0067] Furthermore, to control the reaction time of calcium carbonate in the calcination reaction equipment 3 and improve the reaction effect and efficiency, in this embodiment, the angle between the electromagnetically heated rotary kiln and the horizontal plane is 0-15 degrees, and the reaction section 33 is positioned higher than the preheating section 32 (i.e., tilted upwards from the preheating section 32 to the reaction section 33). The electromagnetically heated rotary kiln is equipped with guide stirring blades, the rotation speed of which is controlled at 1-2 r / min. The time of calcium carbonate in the rotary kiln is 10-13 min, which can be adjusted according to the different particle sizes of the calcium carbonate.

[0068] See Figure 1 In this embodiment, the carbon dioxide collection device 4 includes a first heat exchanger 41, a first bag filter 42, a vacuum pump 43, a compressor 44 and a carbon dioxide storage tank 45 connected in sequence to form a carbon dioxide collection passage.

[0069] Specifically, the carbon dioxide output from the calcination reaction equipment 3 is drawn by the vacuum pump 43, first cooled by heat exchange in the first heat exchanger 41, and then injected into the first bag filter 42 for dust removal. The purity of the carbon dioxide is further improved after dust removal. The dust-removed carbon dioxide is then transported by the vacuum pump 43 to the compressor 44 for compression, and finally the low-temperature, high-purity carbon dioxide is transported to the carbon dioxide storage tank 45 for storage. In addition, the solid matter (CaO) discharged from the first bag filter 42 can also be transported to the carbonation reaction equipment 2 through the first pipeline assembly 5.

[0070] It is worth noting that the carbon dioxide gas output from the calcination reaction equipment 3 has a temperature of approximately 900–950°C. After being cooled by the first heat exchanger 41, the temperature of the discharged carbon dioxide (i.e., the carbon dioxide entering the first bag filter 42) does not exceed 180°C, which meets the operating requirements of the first bag filter 42.

[0071] See Figure 1 In this embodiment, the flue gas preheating supply pipeline 7 includes an induced draft fan 71 and a flue gas preheater 72; the input end of the induced draft fan 71 is connected to the flue gas output end of the wet desulfurization equipment 1, the output end of the induced draft fan 71 is connected to one of the input ends of the flue gas preheater 72, and one of the output ends of the flue gas preheater 72 is connected to the input ends of both the first pipeline assembly 5 and the second pipeline assembly 6, so as to transport the preheated flue gas to the first pipeline assembly 5 and the second pipeline assembly 6. It is worth noting that the flue gas output from the flue gas preheater 72 is the flue gas from the wet desulfurization equipment 1. The flue gas typically includes carbon dioxide, water, oxygen, and nitrogen, accounting for 11.9%, 14.1%, 5.2%, and 68.8% respectively. The content of pollutants sulfur dioxide and dust in this flue gas reaches ultra-low emission levels and is extremely low, negligible. Therefore, it can be directly supplied to the carbonation reaction equipment 2. The moisture in the flue gas is conducive to the absorption of carbon dioxide by calcium oxide. That is, the presence of water can play a role in the hydration pretreatment of calcium oxide. The reaction principle is: CaO + H2O → Ca(OH)2. This reaction process can increase the molar volume of the microstructure of calcium oxide, which can promote the absorption of carbon dioxide by calcium oxide.

[0072] In addition, to ensure good carbon absorption, the molar ratio of carbon dioxide to calcium oxide supplied to the carbonation reaction equipment 2 is maintained at 0.85–0.93. In actual calculations, the amount of carbon-containing flue gas extracted (i.e., the amount of flue gas extracted by the induced draft fan 71 from the wet desulfurization equipment 1) can be calculated based on the carbon-calcium ratio, the scale of carbon dioxide capture, and the properties of the carbon-containing flue gas.

[0073] Furthermore, the induced draft fan 71 is preferably a centrifugal fan with adjustable blades, with a total pressure of 6500-7500 Pa and a fan flow rate calculated based on the carbon-calcium ratio, the scale of carbon dioxide capture, and the parameters of carbon-containing flue gas.

[0074] See Figure 1 In this embodiment, the solid-gas separation device 8 includes a cyclone separator 81, a second heat exchanger 82, and a second bag filter 83. The solid and gaseous substances output from the carbonation reaction device 2 are transported to the cyclone separator 81 for solid-gas separation. The solid (CaCO3) is injected into the calcination reaction device 3, while the gaseous substances enter the second heat exchanger 82 for cooling. The cooled gaseous substances enter the second bag filter 83 for secondary solid-gas separation. The separated solid (CaCO3) is injected into the calcination reaction device 3, while the gaseous substances (actually unreacted flue gas) are transported to the output end of the wet desulfurization device 1.

[0075] Understandably, in order to meet the operational requirements of the second bag filter 83, the temperature of the gaseous material discharged after cooling by the second heat exchanger 82 (i.e., the gaseous material entering the second bag filter 83) should not exceed 180℃.

[0076] In addition, it is known that valves can be installed on the material transport pipelines in this system as needed to control the opening and closing of each pipeline.

[0077] Example 2

[0078] join Figure 4 Based on the above embodiments, in order to achieve the cascade recovery and utilization of energy in the entire system and avoid energy waste, and at the same time, enable the carbon dioxide collection device 4 to achieve carbon dioxide cooling, the solid-gas separation device 8 to achieve (unreacted) flue gas cooling, and the flue gas preheating supply pipeline 7 to achieve the temperature rise of the discharged flue gas, in this embodiment, the first heat exchanger 41 of the carbon dioxide collection device 4, the second heat exchanger 82 of the solid-gas separation device 8, and the flue gas preheater 72 of the flue gas preheating supply pipeline 7 are coupled with the condensate system of the coal-fired unit.

[0079] Existing coal-fired power plant condensate systems typically include multi-stage high-temperature heaters, which use the unit's steam to heat the condensate. For ease of explanation, this embodiment uses a primary high-temperature heater 100, a secondary high-temperature heater 200, and a tertiary high-temperature heater 300 as examples. The condensate after passing through the deaerator is first heated by the tertiary high-temperature heater 300 before entering the secondary high-temperature heater 200, and then entering the primary high-temperature heater 100. The temperature of the condensate heated by the tertiary high-temperature heater 300 (primary heating) (around 100°C) is typically lower than the temperature of the gaseous substances (flue gas) output from the carbonation reaction device 2 (600–650°C) and the temperature of the carbon dioxide output from the calcination reaction device 3 (900–950°C). Therefore, in this embodiment, the condensate after heat exchange in the three-stage high-temperature heater 300 can be used for heat exchange in this system. At the same time, the condensate after heat exchange can also be supplied to the first-stage high-temperature heater 100 and the second-stage high-temperature heater 200 for reheating, so as to realize the cascade recovery and utilization of energy in the entire system, avoid energy waste, and reduce the energy consumption of the entire power plant.

[0080] Specifically, in this embodiment, the three-stage high-temperature heater 300 is connected in series with the second heat exchanger 82, the first heat exchanger 41, and the flue gas preheater 72 to form a condensate water path. The condensate first flows through the second heat exchanger 82, where it exchanges heat with the gaseous substance (flue gas) output from the carbonation reaction device 2, thus cooling the gaseous substance (flue gas). The condensate then flows through the first heat exchanger 41, where it exchanges heat with the carbon dioxide output from the calcination reaction device 3, thus cooling the carbon dioxide. The condensate output from the second heat exchanger 82 can also flow through the flue gas preheater 72 to preheat the flue gas output from the wet desulfurization device 1. The condensate after heat exchange can then flow back to the first-stage high-temperature heater 100 for heating. It can be understood that the condensate outlet and return point can be set according to the temperature of the corresponding high-temperature heater output end, and are not limited to being drawn from the output end of the three-stage high-temperature heater 300 and introduced from the input end of the first-stage high-temperature heater 100.

[0081] Since the flue gas temperature needs to be flexibly controlled within the range of 50 to 140°C, in this embodiment, the condensate output end of the first heat exchanger 41 is also directly connected to the input end of the first-stage high-temperature heater 100 through a branch pipe 400, and a control valve 401 is provided on the branch pipe 400.

[0082] Example 3

[0083] Based on the above embodiment one, this embodiment also provides a method for carbon dioxide capture in a coal-fired power plant, including the following steps:

[0084] The flue gas discharged from the wet desulfurization equipment 1 is fed into the carbonation reaction equipment 2 for carbonation reaction, and solids are generated.

[0085] The solid material is calcined using calcination reaction equipment 3 to generate carbon dioxide and carbon dioxide capture and absorbent.

[0086] Carbon dioxide is collected using carbon dioxide collection device 4;

[0087] The flue gas discharged from the wet desulfurization equipment 1 is transported to the carbonation reaction equipment 2 using the first pipeline assembly 5, and the carbon dioxide capture and absorbent generated by the calcination reaction equipment 3 is transported to the carbonation reaction equipment 2 using the flue gas flowing through the first pipeline assembly 5.

[0088] The flue gas discharged from the wet desulfurization equipment 1 is transported to the carbonation reaction equipment 2 using the second pipeline assembly 6.

[0089] To further control the flexible supply of flue gas, this method also includes the following steps:

[0090] Adjust the flow rate of flue gas delivered by the first pipeline assembly 5 and the second pipeline assembly 6;

[0091] The flue gas discharged from the wet desulfurization equipment 1 is transported in layers to the carbonation reaction equipment 2 using the second pipeline assembly 6.

[0092] In order to achieve flexible control of the flue gas temperature supplied to the first pipeline assembly 5 and the second pipeline assembly 6, this method further includes the following steps: preheating the flue gas discharged from the wet desulfurization equipment 1, and supplying the heated flue gas to the first pipeline assembly 5 and the second pipeline assembly 6.

[0093] In order to collect high-purity carbon dioxide, in this embodiment, the method further includes the following steps: using a solid-gas separation device 8 to separate the solid and gaseous substances output from the output end of the carbonation reaction device 2.

[0094] To reduce the system construction and operating costs, in this embodiment, the method further includes conveying the desulfurizing agent of the wet desulfurization equipment 1 to the calcination reaction equipment 3 for calcination to generate carbon dioxide and carbon dioxide capture and absorbent.

[0095] In summary, this application has at least the following advantages:

[0096] 1. The CaO in this system is derived from the product (CaO) after calcination of limestone (powder) in wet desulfurization equipment 1. On the one hand, compared with existing calcium-based adsorbents, this method does not require pretreatment and has a lower cost, making it more suitable for industrial use. On the other hand, this method allows the system to be directly connected to the existing desulfurizing agent supply tank (for storing limestone powder) in wet desulfurization equipment 1 without the need for additional storage tanks, thereby reducing the manufacturing cost of the system.

[0097] 2. The CaO formed after calcination has a high temperature. This system transports the high-temperature CaO to the carbonation reaction equipment 2 through the first pipeline assembly 5, so that the carbonation reaction equipment 2 can utilize the heat energy of CaO and reduce the energy consumption of the entire system. This system also directly transports the flue gas discharged from the wet desulfurization equipment 1 to the carbonation reaction equipment 2 through the second pipeline assembly 6, so that the flue gas input into the second pipeline assembly 6 can consume the heat generated by the carbonation reaction in the carbonation reaction equipment 2, and at the same time participate in the carbonation reaction as a raw material. In addition, the flue gas and CaO transported by the first pipeline assembly 5, as well as the flue gas transported by the second pipeline assembly 6, can interact to achieve temperature control of the carbonation reaction equipment 2, so as to promote the absorption of carbon dioxide in the flue gas.

[0098] 3. The flue gas in this system originates from the flue gas discharged from the wet desulfurization equipment 1. On the one hand, the flue gas itself contains moisture, which can undergo a hydration reaction with calcium oxide, increasing the molar volume of calcium oxide and thus enhancing the effect of calcium oxide in adsorbing carbon dioxide. On the other hand, the flue gas after desulfurization has low concentrations of sulfur dioxide and dust, which can reduce the risk of blockage in the pipeline of this system.

[0099] 4. The calcination reaction equipment 3 in this system adopts an electromagnetically heated rotary kiln, which eliminates the need for a complex oxygen-enriched combustion system and avoids the impact of combustion exhaust gas on the purity of carbon dioxide, thus facilitating the collection of high-purity carbon dioxide for downstream applications. Simultaneously, the electromagnetically heated rotary kiln has a preheating section 32 and a reaction section 33, which overcomes defects such as over-burning of CaCO3 and localized under-burning due to excessively low temperatures within the calcination reaction equipment 3, thereby improving the CaCO3 decomposition rate. Furthermore, the preheating section 32 and the reaction section 33 are connected to a temperature control component 34, enabling temperature control within the calcination reaction equipment 3 and further improving the CaCO3 decomposition rate.

[0100] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A carbon dioxide capture system for a coal-fired power plant, characterized in that, It includes wet desulfurization equipment (1), carbonation reaction equipment (2), calcination reaction equipment (3), carbon dioxide collection equipment (4), and condensate system of coal-fired power plant; The flue gas output end of the wet desulfurization equipment (1), the carbonation reaction equipment (2), the calcination reaction equipment (3) and the carbon dioxide collection equipment (4) are connected in sequence to form a carbon dioxide capture path; The carbon dioxide collection device (4) includes a first heat exchanger (41) for cooling the carbon dioxide to be stored. It also includes a solid-gas separation device (8), which includes a second heat exchanger (82) for cooling the gaseous material output from the carbonation reaction equipment (2). The second heat exchanger (82) and the first heat exchanger (41) are connected in sequence, and the output ends of the second heat exchanger (82) and the first heat exchanger (41) are both connected to the condensate system of the coal-fired power plant so that heat exchange can be carried out between the second heat exchanger (82) and the condensate system of the coal-fired power plant, and between the first heat exchanger (41) and the condensate system of the coal-fired power plant. The coal-fired power plant condensate system includes a primary high-temperature heater (100), a secondary high-temperature heater (200), and a tertiary high-temperature heater (300), and the condensate temperature at the output end of the primary high-temperature heater (100), the secondary high-temperature heater (200), and the tertiary high-temperature heater (300) decreases sequentially. One of the output ends of the first heat exchanger (41) is connected in sequence to a branch pipe (400), a first three-way valve, a main pipe and the condensate system of the coal-fired power plant. A control valve (401) is provided on the branch pipe (400).

2. The carbon dioxide capture system for a coal-fired power plant according to claim 1, characterized in that, The input end of the second heat exchanger (82) is connected to the output end of the three-stage high-temperature heater (300); The output end of the first heat exchanger (41) is connected to the input end of the first-stage high-temperature heater (100).

3. A carbon dioxide capture system for a coal-fired power plant according to claim 1 or 2, characterized in that, A flue gas preheater (72) for preheating the flue gas output from the wet desulfurization equipment (1) is connected between the flue gas output end of the wet desulfurization equipment (1) and the carbonation reaction equipment (2). The other input end of the first heat exchanger (41) is connected in sequence to the flue gas preheater (72) and the first three-way valve.

4. A carbon dioxide capture system for a coal-fired power plant according to claim 3, characterized in that, The flue gas output from the flue gas preheater (72) has an adjustable temperature range of 50 to 140°C.

5. A carbon dioxide capture system for a coal-fired power plant according to claim 2, characterized in that, The output end of the second heat exchanger (82) is also connected to the output end of the deaerator; The output end of the deaerator and the output end of the three-stage high-temperature heater (300) are respectively connected to the two input ends of the second three-way valve, and the output end of the second three-way valve is connected to the input end of the second heat exchanger (82).

6. A method for utilizing the thermal energy of a carbon dioxide capture system in a coal-fired power plant according to any one of claims 1-5, characterized in that, Includes the following steps: The carbon dioxide to be stored is cooled using the first heat exchanger (41); The gaseous material output from the carbonation reaction equipment (2) is cooled using the second heat exchanger (82); The condensate output from the condensate system of the coal-fired power plant was heated by using the second heat exchanger (82) and the first heat exchanger (41) in succession.

7. A method for utilizing thermal energy according to claim 6, characterized in that: The condensate output from the condensate system of the coal-fired power plant is heated by using the second heat exchanger (82) and the first heat exchanger (41) in sequence, including the following steps: The condensate output from the three-stage high-temperature heater (300) is delivered to the second heat exchanger (82) for heating; The condensate after the first heating is sent to the first heat exchanger (41) for a second heating; The condensate from the secondary heating is delivered to the input end of the primary high-temperature heater (100).

8. A method for utilizing thermal energy according to claim 7, characterized in that: The process of delivering the condensate output from the three-stage high-temperature heater (300) to the second heat exchanger (82) for heating includes the following steps: The condensate output from the deaerator is mixed with the condensate output from the three-stage high-temperature heater (300) and then sent to the second heat exchanger (82) for heating.

9. A method for utilizing thermal energy according to claim 6, characterized in that: It also includes the following steps: By adjusting the valve opening of the control valve (401), the amount of flue gas delivered from the first heat exchanger (41) to the flue gas preheater (72) is controlled, thereby adjusting the flue gas temperature output by the flue gas preheater.

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