High-temperature flue gas CO2 trapping system and method for waste incineration power plant

Abstract

The invention belongs to the technical field of CO2 trapping, and particularly relates to a high-temperature flue gas CO2 trapping system and method for a waste incineration power plant, and the system comprises a flue gas generation device, a flue gas heat exchanger, a fan, a reaction tower, a powder bin and an ash storage bin; a heat source of the flue gas heat exchanger is high-temperature flue gas, and a cold source is low-temperature clean flue gas; the smoke heat exchanger is used for adjusting the temperature of high-temperature smoke. The fan is connected with a heat source outlet of the flue gas heat exchanger; the reaction tower is a countercurrent contact type reaction tower, a high-temperature flue gas inlet and an absorbent outlet are positioned at the lower part, and an absorbent inlet and a reflux flue gas outlet are positioned at the top; the high-temperature flue gas inlet is connected with the fan, the backflow flue gas outlet is connected with the flue gas generating device, the absorbent inlet is connected with the powder bin, and the absorbent outlet is connected with the ash storage bin; and a cold source outlet of the flue gas heat exchanger is connected with the flue gas generating device. Compared with the prior art, the method provided by the invention solves the problem that the removal efficiency of CO2 is still at a lower level in the prior art. According to the scheme, the capture of CO2 in the flue gas generated by the garbage incinerator is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of CO2 capture, and in particular relates to a system and method for capturing CO2 from high-temperature flue gas in a waste incineration power plant. Background Art

[0002] The large-scale emission of greenhouse gases such as carbon dioxide (CO2) is the main cause of global warming. In the industrial production process, coal-fired power plants and waste incineration power plants are the main sources of CO2 emissions. Therefore, controlling and reducing CO2 emissions in power production is of great significance to alleviating global warming.

[0003] In recent years, carbon capture technologies that have reached technical feasibility or demonstrated and commercial operation levels include amine solution absorption, low-temperature separation and direct air capture, such as the waste incineration flue gas treatment system and treatment method disclosed in CN113877406A. However, there are still factors such as low overall adsorption efficiency, poor recycling effect and high economic cost that prevent large-scale popularization.

[0004] Calcium Loop (CaL) technology utilizes the carbonation / calcination reaction between CaO and CaCO₃, enabling a multi-cycle CO₂ capture pathway between the carbonation reactor and the calciner. CO₂ in the flue gas is captured by CaO and other calcium-based materials at 600-700°C in the carbonation reactor, forming CaCO₃ as a product and outputting pure carbon-free / low-carbon flue gas. A portion of the CaCO₃ product is then recycled to the calciner, where it is calcined at temperatures exceeding 900°C in a high-CO₂ atmosphere to release the CO₂ captured in the previous stage and produce new CaO particles. The released CO₂ gas is then condensed, compressed, and bottled. The new CaO particles are then fed back to the carbonation reactor to begin a new CO₂ capture cycle. This CO₂ capture technology, due to its broad availability of calcium-based materials and high CO₂ removal rates, has been widely adopted in carbonation plant development and high-temperature flue gas applications in large and medium-sized industries. Considering that the flue gas emitted by waste incineration power plants has complex composition and high temperature, the use of CO2 capture technology based on calcium-based absorbents can adapt to complex flue gas scenarios and directly utilize high-temperature flue gas to reduce energy consumption.

[0005] For example, CN106215682A discloses a CO2 capture method for a gas-fired power generation system. In this method, air is fed into a compressor, compressed to a specified pressure, and then fed into a gas turbine or internal combustion engine. The compressed air is mixed with injected natural gas and burned in the gas turbine or internal combustion engine to form high-temperature, high-pressure gas. The gas expands and produces work, driving the impeller to rotate, thereby driving the generator to generate electricity. The outlet of the gas turbine or internal combustion engine is connected to the bottom of a carbonation reactor, which is used to pass the CO2-rich gas produced by the gas turbine or internal combustion engine into the carbonation reactor to remove the CO2 from the gas. However, this method is mainly aimed at removing CO2 from the gas. The feed gas is significantly different from the gas after combustion in a waste incineration power plant, and is affected by impurities and cannot be directly applied. In addition, the carbonation reactor used in this method is difficult to fully utilize the calcium-based absorbent and has a limited contact area with CO2. As a result, although its removal efficiency is higher than that of conventional commercial carbon capture technology, it still cannot reach a high level. Summary of the Invention

[0006] The present invention aims to address at least one of the aforementioned issues by providing a system and method for capturing CO2 from high-temperature flue gas in waste incineration power plants. This approach addresses the low efficiency of existing technologies for deep CO2 removal from flue gas in waste incineration power plants. This solution captures CO2 from flue gas generated by waste incinerators. During the capture process, the flue gas is brought into countercurrent contact with a calcium-based absorbent through temperature and speed control, resulting in high removal efficiency and low cost.

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

[0008] The first aspect of the present invention discloses a high-temperature flue gas CO2 capture system for a waste incineration power plant, comprising a flue gas generating device, a flue gas heat exchanger, a fan, a reaction tower, a powder silo and an ash storage silo;

[0009] The heat source of the flue gas heat exchanger is the high-temperature flue gas from the furnace of the flue gas generating device, and the cold source of the flue gas heat exchanger is the low-temperature clean flue gas from the flue gas generating device; the flue gas heat exchanger is used to adjust the temperature of the high-temperature flue gas entering the reaction tower;

[0010] The fan is connected to the heat source outlet of the flue gas heat exchanger; the fan is used to adjust the flow rate of the high-temperature flue gas entering the reaction tower;

[0011] The reaction tower is a countercurrent contact reaction tower, with the high-temperature flue gas inlet and absorbent outlet located at the bottom of the reaction tower, and the absorbent inlet and reflux flue gas outlet located at the top of the reaction tower; the high-temperature flue gas inlet is connected to the fan, the reflux flue gas outlet is connected to the furnace of the flue gas generating device, the absorbent inlet is connected to the powder bin, and the absorbent outlet is connected to the ash storage bin;

[0012] The cold source outlet of the flue gas heat exchanger is connected to the furnace of the flue gas generating device.

[0013] Preferably, a flue gas purification device and a regulating valve are further provided between the flue gas generating device and the flue gas heat exchanger.

[0014] Preferably, a water-cooled heat exchanger is further provided between the fan and the smoke generating device, and the water-cooled heat exchanger and the smoke heat exchanger are connected in parallel between the fan and the smoke generating device;

[0015] The heat source of the water-cooled heat exchanger is the high-temperature flue gas from the furnace of the flue gas generating device, and the cold source of the water-cooled heat exchanger is the cooling water introduced into the system through the cooling water pipeline.

[0016] Preferably, a switch valve is further provided between the water-cooled heat exchanger and the flue gas generating device.

[0017] Preferably, inside the reaction tower, between the high-temperature flue gas inlet and the reflux flue gas outlet, a plurality of orifice plates are alternately arranged along the height direction, and the plurality of orifice plates form a Z-shaped flow channel for the absorbent to pass through;

[0018] A flow equalizing plate is provided between the lowermost primary orifice plate and the high-temperature flue gas inlet.

[0019] Preferably, the reaction tower is a vibration tower, and a mechanical push-pull rod for assisting the flow of the absorbent is further provided inside the reaction tower.

[0020] Preferably, a vacuum loader and a powder feeder connected in sequence are further provided between the powder bin and the absorbent inlet of the reaction tower;

[0021] The powder feeder is arranged higher than the absorbent inlet of the reaction tower.

[0022] Preferably, the flue gas generating device is a waste incinerator, and the flue gas purification device is a gravity settling chamber or an inertial dust collector.

[0023] Preferably, the lower portion of the reaction tower is further connected to a purge gas source for periodically purging the reaction tower.

[0024] The second aspect of the present invention discloses a method for capturing CO2 from high-temperature flue gas in a waste incineration power plant, using any of the above-described systems;

[0025] The method described is:

[0026] A stream of high-temperature flue gas is extracted from the furnace of the flue gas generating device as a heat source and input into the flue gas heat exchanger. A stream of low-temperature clean flue gas is then extracted from the flue gas generating device as a cold source and input into the flue gas heat exchanger. The two flue gases exchange heat.

[0027] The high-temperature flue gas after heat exchange enters the reaction tower through the high-temperature flue gas inlet through the fan, and reacts with the absorbent from the powder silo in countercurrent. The high-temperature flue gas after the reaction returns to the furnace of the flue gas generating device through the reflux flue gas outlet, and the absorbent after the reaction is sent to the ash storage silo;

[0028] The low-temperature clean flue gas after heat exchange returns to the furnace of the flue gas generating device.

[0029] Preferably, the temperature of the high-temperature flue gas is 800°C-900°C, and the temperature of the low-temperature clean flue gas is 400°C-500°C; the temperature of the high-temperature flue gas entering the reaction tower is 550°C-600°C, and the flow rate is 5-10m / s; the absorbent is fly ash-CaO absorbent.

[0030] Preferably, the absorbent after the reaction can be chelated and landfilled together with the garbage ash to achieve direct mineralization and storage of CO2 and safe treatment of toxic substances in the flue gas of garbage incineration; or, the absorbent after the reaction can be placed in a high-temperature calcining furnace (above 920°C) for full calcination to achieve the release of CO2 and activation of the absorbent.

[0031] The working principle of the present invention is:

[0032] A stream of high-temperature flue gas is extracted from the high-temperature section of the furnace of the flue gas generating device and sent to the bottom of the reaction tower. The absorbent is continuously fed into the reaction tower from the top of the reaction tower through the absorbent inlet, forming a gas-solid countercurrent to achieve a full carbonation reaction. Specifically: a multi-stage symmetrical orifice plate is arranged in the tower to allow the airflow to penetrate in one direction, and the absorbent realizes a slow Z-shaped flow between the orifice plates at each level in the reaction tower; the flue gas to be treated enters the reaction tower from the bottom and slowly passes through the absorbent bed layers at each level after the action of the equalizing plate. The flue gas achieves a low-resistance slow countercurrent of the flue gas and the absorbent by controlling the flue gas flow rate, achieving the purpose of full carbonation and continuous reaction. The low-carbon flue gas treated in the reaction tower is returned to the furnace of the flue gas generating device through the upper reflux flue gas outlet to maintain the heat quality of the flue gas; and the reacted absorbent enters the ash storage bin through the lower absorbent outlet and waits for further processing.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The high-temperature flue gas CO2 capture system designed by the present invention for use in waste incineration power plants mainly adopts a gas-solid countercurrent carbonation reaction mode in the reaction tower. The absorbent continuously enters the reaction tower through the powder feeding system (powder bin, vacuum loader and powder feeder) to complete the top-down transportation process; the flue gas realizes a uniform diffusion process from bottom to top through the flow equalizing plate. In this process, the absorbent is slowly flowed and fully contacted with the flue gas through mechanical vibration in the reaction tower. The countercurrent mode of gas-solid reaction has the advantages of efficient mass transfer and extended contact time; and the low-resistance vibrating self-flowing reaction tower adopted in this scheme is based on the gas-solid countercurrent reaction mode. Through the Z-shaped slow flow of the absorbent in the reaction tower, the contact time is maximized while maintaining a certain size of the reaction tower, and ultimately achieves the purpose of efficient CO2 capture rate.

[0035] (2) The high-temperature flue gas CO2 capture system designed by the present invention for use in waste incineration power plants utilizes a highly cost-effective fly ash-CaO absorbent. The resulting high-calcium fly ash has numerous advantages, including its vast reserves and near-free price; the favorable doping of inert materials and various metal elements in the fly ash, which provides a path for the recycling of solid waste; strong compatibility with high-temperature flues and waste incineration scenarios; and physical and chemical properties that facilitate carbon sequestration and transport.

[0036] (3) The high-temperature flue gas CO2 capture system designed by the present invention for use in waste incineration power plants fully utilizes the heat of the high-temperature flue gas in the furnace of the waste incinerator, and through heat exchange with the low-temperature flue gas after treatment in the waste incinerator and supplementary heat exchange with condensed water as needed, fully controls the optimal reaction temperature window in the reaction tower, greatly reducing the system's additional heating energy consumption. The carbonation reaction of the calcium-based absorbent is an exothermic reaction. The sufficient unit particle contact time (including CO2 and absorbent particles) in the reaction tower also makes the exothermic effect of the carbonation reaction more concentrated, which plays a key role in maintaining the required temperature of the reaction tower and reducing external heat input.

[0037] (4) The high-temperature flue gas CO2 capture system designed for waste incineration power plants has a compact design, simple structure, and convenient coupling, which can further reduce the difficulty and construction cost of equipment modification for industrial applications. The entire system is easy to disassemble, install, and maintain, making it suitable for CO2 capture in coal-fired power plants, waste incineration power plants, and other scenarios.

[0038] (5) The high-temperature flue gas CO2 capture system designed by the present invention for use in waste incineration power plants provides flexible and diverse methods for the subsequent treatment of the captured CO2. For waste incineration power plants, the fully reacted fly ash-CaO absorbent can be directly chelated with the waste ash and landfilled to achieve direct mineralization and storage. For large-scale high-temperature flue gas scenarios, the reacted absorbent can be recycled and calcined for multiple uses. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a structural diagram of a high-temperature flue gas CO2 capture system for a waste incineration power plant;

[0040] In the figure: 1. Flue gas generating device; 2. Reaction tower; 3. Vacuum loader; 4. Powder feeder; 5. Ash storage bin; 6. Powder bin; 7. Flue gas purification device; 8. Flue gas heat exchanger; 9. Water-cooled heat exchanger; 10. Purge air source; 11. High-temperature flue gas inlet; 12. Return flue gas outlet; 13. Absorbent inlet; 14. Fan; 15. Hot flue gas duct; 16. Cold flue gas duct; 17. Cooling water duct; 18. Flue gas return duct; 19. Orifice plate; 20. Flow equalizing plate. DETAILED DESCRIPTION

[0041] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. In the following description, unless otherwise specified, the materials used can be purchased from commercial products, the methods used can be conventional means in the art, and other matters not mentioned can be prior art.

[0042] Example 1

[0043] A high temperature flue gas CO2 capture system for waste incineration power plants, such as Figure 1 As shown, it includes a flue gas generating device 1, a flue gas heat exchanger 8, a fan 14, a reaction tower 2, a powder bin 6 and an ash storage bin 5;

[0044] The heat source of the flue gas heat exchanger 8 is the high-temperature flue gas from the furnace of the flue gas generating device 1, and the cold source of the flue gas heat exchanger 8 is the low-temperature clean flue gas from the flue gas generating device 1; the flue gas heat exchanger 8 is used to adjust the temperature of the high-temperature flue gas entering the reaction tower 2;

[0045] The fan 14 is connected to the heat source outlet of the flue gas heat exchanger 8; the fan 14 is used to adjust the flow rate of the high-temperature flue gas entering the reaction tower 2;

[0046] The reaction tower 2 is a countercurrent contact reaction tower 2, with a high-temperature flue gas inlet 11 and an absorbent outlet located at the bottom of the reaction tower 2, and an absorbent inlet 13 and a return flue gas outlet 12 located at the top of the reaction tower 2; the high-temperature flue gas inlet 11 is connected to a fan 14, the return flue gas outlet 12 is connected to the furnace of the flue gas generating device 1, the absorbent inlet 13 is connected to the powder bin 6, and the absorbent outlet is connected to the ash storage bin 5;

[0047] The cold source outlet of the flue gas heat exchanger 8 is connected to the furnace of the flue gas generating device 1 .

[0048] More specifically, in this embodiment:

[0049] The main body of the system consists of a flue gas generating device 1, a flue gas purification device 7, a flue gas heat exchanger 8, a fan 14, a reaction tower 2, a powder feeding subsystem (powder bin 6, a vacuum loader 3 and a powder feeder 4), an ash storage bin 5, and an optional water-cooled heat exchanger 9 and a purge air source 10. Figure 1 shown.

[0050] Flue gas generator 1, specifically a waste incinerator, is connected to flue gas purification device 7 via a hot flue gas duct 15 in the high-temperature section of the furnace to extract high-temperature flue gas. Downstream of this flue gas duct, it is also connected to the cold-source inlet of flue gas heat exchanger 8 via a cold flue gas duct 16 to extract treated, low-temperature clean flue gas. A regulating valve is also provided between flue gas generator 1 and flue gas purification device 7 to determine the amount of high-temperature flue gas extracted based on the target processing capacity.

[0051] The flue gas purification device 7 can utilize a gravity settling chamber to settle most of the dust and ash in the high-temperature flue gas. Alternatively, a low-resistance inertial dust collector, such as a cyclone dust collector, can be used to separate most of the particles and ash contained in the high-temperature flue gas, converting the flue gas into pure flue gas with a low dust concentration. The outlet of the flue gas purification device 7 is connected to the heat source inlet of the flue gas heat exchanger 8 and the water-cooled heat exchanger 9, respectively.

[0052] The flue gas heat exchanger 8 processes the high-temperature flue gas and the low-temperature clean flue gas drawn from the flue gas generator 1 for heat exchange, thereby controlling the temperature of the high-temperature flue gas entering the downstream reaction tower 2. The heat source outlet of the flue gas heat exchanger 8 is connected to the fan 14; the cold source outlet of the flue gas heat exchanger 8 returns to the furnace of the flue gas generator 1 through the flue gas return duct 18.

[0053] The water-cooled heat exchanger 9, serving as an auxiliary heat exchanger, is activated only when the flue gas heat exchanger 8's temperature control is insufficient and the high-temperature flue gas cannot reach the target temperature. Therefore, the water-cooled heat exchanger 9 and the flue gas heat exchanger 8 are connected in parallel between the flue gas purification device 7 and the fan 14. An on-off valve is also provided on the branch line between the water-cooled heat exchanger 9 and the flue gas purification device 7 to control the activation of the water-cooled heat exchanger 9. The cold source of the water-cooled heat exchanger 9 is cooling water, which is connected to and drawn from outside the system via the cooling water pipe 17; the heat source outlet of the water-cooled heat exchanger 9 is also connected to the fan 14.

[0054] By setting up the flue gas heat exchanger 8 and the water-cooled heat exchanger 9, the high-temperature flue gas entering the reaction tower 2 can be controlled at a suitable reaction temperature, with high reaction efficiency; and, preferentially using a single flue gas heat exchanger 8 to perform heat exchange and temperature control on the high-temperature flue gas, can maximize the utilization and circulation of energy within the system and reduce the energy loss caused by the introduction of external cooling water.

[0055] Fan 14 is a high-temperature fan 14 that regulates the flow rate and velocity of the high-temperature flue gas entering reaction tower 2. This controls the contact time between the high-temperature flue gas and the absorbent within reaction tower 2, thereby achieving efficient reaction and capture. The output end of fan 14 is connected to the high-temperature flue gas inlet 11 at the bottom of reaction tower 2.

[0056] The reaction tower 2 is specifically a countercurrent contact reaction tower 2, more specifically a low-resistance vibrating gravity flow reaction tower 2; a high-temperature flue gas inlet 11 is provided at its lower portion, a return flue gas outlet 12 is provided at its top, an absorbent inlet 13 is provided at its top, and an absorbent outlet is provided at its bottom. Orifice plates 19 are staggered along the height direction between the high-temperature flue gas inlet 11 and the return flue gas outlet 12, and a flow equalizing plate 20 is provided between the lowest level orifice plate 19 and the high-temperature flue gas inlet 11; in addition, the opening size of the orifice plate 19 is smaller than the particle size of the absorbent, or the surface of the orifice plate 19 is covered with a metal mesh film with an aperture smaller than the particle size of the absorbent, so that the absorbent can only flow slowly from top to bottom along the Z-shaped flow channel formed by the orifice plate 19, while the high-temperature flue gas flows from bottom to top through the openings of the orifice plate 19 after achieving equalization on the flow equalizing plate 20, forming a gas-solid countercurrent contact with sufficient contact time. After the reaction, the high-temperature flue gas flows out of the reflux flue gas outlet 12 and returns to the furnace of the flue gas generating device 1 through the flue gas reflux pipe 18. The reacted absorbent (waste material) is discharged from the bottom of the reaction tower 2 to the ash storage bin 5 for further processing. In addition, a mechanical push-pull rod can be installed in the reaction tower 2 as needed. The push-pull action of the mechanical push-pull rod inside the reaction tower 2 assists the slow flow of the absorbent along the Z-shaped flow channel.

[0057] The powder feeding subsystem, in this embodiment, specifically comprises a powder silo 6, a vacuum loader 3, and a powder feeder 4. These are sequentially connected, and the powder feeder 4 is connected to the absorbent inlet 13 of the reaction tower 2. This ensures that the solid absorbent stored in the silo 6 is continuously transported to the reaction tower 2 for reaction. In this embodiment, the silo 6, powder feeder 4, and ash storage bin 5 are all located on a base platform, while the vacuum loader 3 is positioned two meters above the reaction tower 2. The purpose of this powder feeding subsystem is to achieve a continuous absorbent supply, utilizing the system's frame structure and elevator installation layout, but this is not limited to the single model described above.

[0058] The waste collected in the ash storage bin 5 can be treated in different ways according to different target needs. For example, in the CO2 removal scenario of a waste incineration power plant, the fully reacted absorbent can be chelated and landfilled together with the waste ash to achieve direct mineralization and storage of CO2 and safe treatment of toxic substances in the waste incineration flue gas; or, the fully reacted absorbent enters a high-temperature calcining furnace (above 920°C) for full calcination to achieve the release of CO2 and activation of the absorbent. The CO2 gas is then compressed and purified, and the activated absorbent is reused in the reaction tower 2 to capture CO2.

[0059] The purge gas source 10, specifically compressed air, is pumped into the reaction tower 2 by a compressed air pump for regular purge to clean the reaction tower 2. The compressed air pump is also connected to the lower part of the reaction tower 2 to purge from bottom to top.

[0060] The specific capture process of this system is as follows:

[0061] The hot flue gas duct 15 extracts a stream of high-temperature flue gas at 800°C-900°C from the high-temperature section of the furnace of the flue gas generating device 1 (the flue gas volume is determined by the processing capacity and is controlled by a regulating valve provided on the hot flue gas duct 15). The flue gas first enters the flue gas purification device 7 to achieve the sedimentation of most of the ash and particles in the flue gas, thereby obtaining a relatively pure carbon-containing flue gas. The pure flue gas passing through the flue gas purification device 7 preferentially enters the flue gas heat exchanger 8, which in turn extracts a stream of low-temperature clean flue gas at 400°C-500°C from the flue gas generating device 1. The temperature of the above-mentioned pure flue gas is adjusted by heat exchange between the two flue gases, so that the optimal carbonation reaction temperature window (usually 550°C-600°C) is reached after entering the low-resistance vibrating gravity reaction tower 2. If the temperature control effect of the extracted low-temperature flue gas is insufficient, the on-off valve is opened to allow some of the purified flue gas from the flue gas purification device 7 to enter the water-cooled heat exchanger 9. Cooling water is also drawn through the cooling water pipe 17 into the water-cooled heat exchanger 9, providing auxiliary temperature control for the flue gas. Finally, the temperature-controlled flue gas is merged into the main hot flue gas pipe and, along with the temperature-controlled flue gas from the flue gas heat exchanger 8, is fed by the fan 14, which adjusts the speed to 5-10 m / s, before reaching the high-temperature flue gas inlet 11 of the reaction tower 2. The flow of these flue gases is entirely controlled by the high-temperature fan 14 and various valves.

[0062] The flue gas at the appropriate temperature entering the high-temperature flue gas inlet 11 passes through the equalizing plate 20 to achieve uniform flow in the reaction tower 2. The absorbent is stored in the powder bin 6 located on the base platform, reaches the upper platform through the vacuum loader, and continuously enters the interior of the reaction tower 2 from the absorbent inlet through the powder feeder 4. The flue gas and the absorbent form a gas-solid countercurrent to achieve a sufficient carbonation reaction. Multiple levels of orifice plates 19 are symmetrically arranged in the tower. The upper surface of the orifice plates 19 is covered with a metal mesh to achieve unidirectional airflow. Under the help of vibration and mechanical assistance, the absorbent achieves a Z-shaped slow flow between the orifice plates 19 at each level; the flue gas to be treated enters the reaction tower 2 from the bottom and slowly passes through the absorbent bed layers at each level through the equalizing plate 20. By controlling the flue gas flow rate, a low-resistance slow counterflow of the flue gas and the absorbent is achieved, achieving the purpose of sufficient carbonation and continuous reaction. The low-carbon flue gas absorbed and treated in the reaction tower 2 is returned to the furnace through the upper reflux flue gas outlet 12 and the flue gas reflux pipe 18 to maintain the heat quality of the flue gas. The reacted absorbent enters the ash storage bin 5 through the lower outlet for further processing. The countercurrent method of gas-solid reaction has the advantages of efficient mass transfer and extended contact time. Based on the gas-solid countercurrent reaction method, the low-resistance vibrating self-flowing reaction tower 2 of this solution maximizes the contact time while maintaining a certain size of the reaction tower 2 through the slow Z-shaped flow of the absorbent in the reaction tower 2, ultimately achieving the goal of high CO2 capture rate.

[0063] To further reduce CO2 capture costs, this system uses an inexpensive fly ash-CaO absorbent. This absorbent is made from a mixture of fly ash and CaO in a specific ratio. This significantly reduces absorbent costs while mitigating the common issues with calcium-based absorbents, such as long-term absorption and sintering deactivation after recycling.

[0064] According to tests, the CO2 removal rate of this system can reach 95% under optimal operating conditions and can operate stably for 72 hours; the fly ash-CaO absorbent used in this system can achieve a carbonation conversion rate of 98% in laboratory-scale tests.

[0065] In summary, the present invention comprehensively utilizes the calcium-based absorbent CO2 removal technology based on calcium circulation (CaL) and the gas-solid countercurrent reaction principle, and designs a high-temperature flue gas CO2 capture system for use in waste incineration power plants, thereby achieving low-cost and efficient CO2 removal in high-temperature flue gas scenarios such as waste incineration power plants.

[0066] In order to solve the problem of low-cost and high-efficiency removal of CO2 in high-temperature flue gas scenarios such as waste incineration power plants, the present invention provides a high-temperature flue gas CO2 capture system for waste incineration power plants. A stream of high-temperature flue gas is extracted from the high-temperature section of the waste incinerator furnace and sent into a low-resistance vibrating gravity reaction tower 2. After most of the CO2 is removed at a suitable temperature (about 600°C), it is returned to the furnace. The advantages of this system are: (1) high CO2 capture rate; (2) performance improvement and significant cost reduction brought about by the use of a specific fly ash-CaO absorbent; (3) the simple structure and convenient coupling characteristics of the reaction tower 2 can further reduce the difficulty of equipment modification and construction costs for industrial applications; (4) the absorbent after reaction can be chelated and landfilled together with the waste ash to achieve direct mineralization and storage of CO2, fully adapting to the characteristics of the absorbent that is difficult to recover due to the complexity of waste incineration flue gas, while reducing the cost of CO2 transportation and storage. In summary, the present invention provides a high-temperature flue gas CO2 capture system applied to waste incineration power plants to fill the technical gap of existing CO2 capture systems, and can also be extended to CO2 removal applications in high-temperature flue gas scenarios in larger-scale industrial fields.

[0067] The present invention solves the actual demand for low-cost and high-efficiency CO2 emission reduction in existing waste incineration power plants by proposing a complete CO2 capture system for waste incinerators.

[0068] (1) By adopting a low-resistance gas-solid countercurrent carbonation reaction mode, a two-way uniform flow of the absorbent material and the flue gas is achieved, overcoming the problems of insufficient reaction time and contact efficiency of the original fixed-bed reactor, significantly improving the contact rate between the flue gas and the decarbonizer, effectively reducing the clustering and sintering of the absorbent, and ultimately improving the CO2 capture rate. The countercurrent mode of the gas-solid reaction has the advantages of efficient mass transfer and extended contact time. Based on the gas-solid countercurrent reaction mode, the low-resistance vibrating self-flowing reaction tower 2 adopts a top-down vibrating fluidized bed design, which effectively reduces the material accumulation phenomenon at the feed port. Through the Z-shaped slow flow of the absorbent in the reaction tower 2, the contact time is maximized while maintaining a certain size of the reaction tower 2, thereby improving the carbonization efficiency and ensuring the safe and stable operation of the carbon emission reduction furnace, ultimately achieving the purpose of extending the service life of the carbon emission reduction furnace and achieving a high CO2 capture rate.

[0069] (2) By using the highly cost-effective fly ash-CaO absorbent, the high CO2 capture costs of existing CO2 capture technologies and systems can be reduced, and the CO2 capture efficiency and carbonation conversion rate of the absorbent can be improved. High-calcium fly ash stands out due to its many advantages, including its huge reserves and near-free price; the favorable doping of inert materials and various metal elements in fly ash; providing a path for the recycling of solid waste; strong compatibility with high-temperature flues and waste incineration scenarios; and physical and chemical properties that facilitate carbon sequestration and carbon transport.

[0070] (3) By fully utilizing the high-temperature flue gas from the waste incinerator furnace to control the optimal reaction temperature window within reaction tower 2, the high energy consumption problem of the existing carbonation reactor is overcome. The carbonation reaction of the calcium-based absorbent is an exothermic reaction. The sufficient unit particle contact time (including CO2 and absorbent particles) within reaction tower 2 also makes the exothermic effect of the carbonation reaction more concentrated, which plays a key role in maintaining the required temperature of reaction tower 2 and reducing external heat input.

[0071] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A high-temperature flue gas CO2 capture system for a waste incineration power plant, characterized in that: It comprises a smoke generating device (1), a smoke heat exchanger (8), a fan (14), a reaction tower (2), a powder bin (6) and an ash storage bin (5); The heat source of the flue gas heat exchanger (8) is the high-temperature flue gas from the furnace of the flue gas generating device (1), and the cold source of the flue gas heat exchanger (8) is the low-temperature clean flue gas from the flue gas generating device (1); the flue gas heat exchanger (8) is used to adjust the temperature of the high-temperature flue gas entering the reaction tower (2); The fan (14) is connected to the heat source outlet of the flue gas heat exchanger (8); the fan (14) is used to adjust the flow rate of the high-temperature flue gas entering the reaction tower (2); The reaction tower (2) is a countercurrent contact reaction tower, the high-temperature flue gas inlet (11) and the absorbent outlet are located at the bottom of the reaction tower (2), and the absorbent inlet (13) and the return flue gas outlet (12) are located at the top of the reaction tower (2); the high-temperature flue gas inlet (11) is connected to the fan (14), the return flue gas outlet (12) is connected to the furnace of the flue gas generating device (1), the absorbent inlet (13) is connected to the powder bin (6), and the absorbent outlet is connected to the ash storage bin (5); The cold source outlet of the flue gas heat exchanger (8) is connected to the furnace of the flue gas generating device (1).

2. The high-temperature flue gas CO2 capture system of a waste incineration power plant according to claim 1 is characterized in that: A flue gas purification device (7) and a regulating valve are also provided between the flue gas generating device (1) and the flue gas heat exchanger (8).

3. The high-temperature flue gas CO2 capture system of a waste incineration power plant according to claim 1, characterized in that: A water-cooled heat exchanger (9) is further provided between the fan (14) and the smoke generating device (1), and the water-cooled heat exchanger (9) and the smoke heat exchanger (8) are connected in parallel between the fan (14) and the smoke generating device (1); The heat source of the water-cooled heat exchanger (9) is the high-temperature flue gas from the furnace of the flue gas generating device (1), and the cold source of the water-cooled heat exchanger (9) is the cooling water introduced into the system through the cooling water pipe (17).

4. The high-temperature flue gas CO2 capture system of a waste incineration power plant according to claim 3 is characterized in that: A switch valve is also provided between the water-cooled heat exchanger (9) and the smoke generating device (1).

5. The high-temperature flue gas CO2 capture system of a waste incineration power plant according to claim 1, characterized in that: Inside the reaction tower (2), between the high-temperature flue gas inlet (11) and the reflux flue gas outlet (12), a plurality of orifice plates (19) are alternately arranged along the height direction, and the plurality of orifice plates (19) form a Z-shaped flow channel for the absorbent to pass through; A flow equalizing plate (20) is provided between the lowermost primary orifice plate (19) and the high-temperature flue gas inlet (11).

6. The high-temperature flue gas CO2 capture system of a waste incineration power plant according to claim 1, characterized in that: The reaction tower (2) is a vibration tower, and a mechanical push-pull rod for assisting the flow of the absorbent is also provided inside the reaction tower (2).

7. The high-temperature flue gas CO2 capture system of a waste incineration power plant according to claim 1, characterized in that: A vacuum loader (3) and a powder feeder (4) connected in sequence are further provided between the powder bin (6) and the absorbent inlet (13) of the reaction tower (2); The powder feeder (4) is arranged above the absorbent inlet (13) of the reaction tower (2).

8. The high-temperature flue gas CO2 capture system of a waste incineration power plant according to claim 1, characterized in that: The lower part of the reaction tower (2) is also connected to a purge gas source (10) for periodically purging the reaction tower (2).

9. A method for capturing CO2 from high-temperature flue gas in a waste incineration power plant, characterized in that: Using the system according to any one of claims 1 to 8; The method described is: A stream of high-temperature flue gas is extracted from the furnace of the flue gas generating device (1) as a heat source and input into the flue gas heat exchanger (8), and a stream of low-temperature clean flue gas is extracted from the flue gas generating device (1) as a cold source and input into the flue gas heat exchanger (8), and the two streams of flue gas exchange heat; The high-temperature flue gas after heat exchange enters the reaction tower (2) through the high-temperature flue gas inlet (11) through the fan (14), and reacts with the absorbent from the powder bin (6) in countercurrent. The high-temperature flue gas after the reaction returns to the furnace of the flue gas generating device (1) through the reflux flue gas outlet (12), and the absorbent after the reaction is sent to the ash storage bin (5); The low-temperature clean flue gas after heat exchange returns to the furnace of the flue gas generating device (1).

10. The method for capturing CO2 from high-temperature flue gas in a waste incineration power plant according to claim 9, characterized in that: The temperature of the high-temperature flue gas is 800°C-900°C, and the temperature of the low-temperature clean flue gas is 400°C-500°C; the temperature of the high-temperature flue gas entering the reaction tower (2) is 550°C-600°C, and the flow rate is 5-10m / s; the absorbent is fly ash-CaO absorbent.

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