Matching method and system for collaborative optimization of in-furnace enhanced desulfurization and after-furnace flue gas desulfurization of circulating fluidized bed boiler
By optimizing the load distribution and operating parameters of flue gas desulfurization in and after the furnace of the circulating fluidized bed boiler, and by adopting limestone staged addition and various flue gas desulfurization processes, the problem of low desulfurization efficiency of the circulating fluidized bed boiler under low load operation has been solved, and efficient and economical SO2 emission control has been achieved.
Patent Information
- Application Number
- CN202511339373.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-18
- Publication Date
- 2025-11-07
AI Technical Summary
Existing circulating fluidized bed boilers have low desulfurization efficiency when operating at low loads, and the in-furnace desulfurization and post-furnace flue gas desulfurization are poorly matched when burning coal with different sulfur contents, resulting in decreased desulfurization efficiency and increased costs.
By using the sulfur content of different coal types as the inlet constraint and the SO2 emission concentration limit as the outlet constraint, the load distribution and operating parameters of flue gas desulfurization in and after the furnace of the circulating fluidized bed boiler are optimized. Processes such as limestone staged addition, humidification activation flue gas desulfurization, spray drying flue gas desulfurization, or limestone-gypsum wet flue gas desulfurization are adopted to achieve synergistic optimization of in-furnace enhanced desulfurization and after-furnace flue gas desulfurization.
It significantly improves the desulfurization efficiency of circulating fluidized bed boilers under full load and deep peak shaving low load conditions, reduces the investment and operating costs of desulfurization systems, and achieves ultra-low control of SO2 emissions.
Smart Images
Figure CN120907141A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of thermal power generation, in particular to a matching method and system for synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization of a circulating fluidized bed boiler. BACKGROUND
[0002] The existing in-furnace desulfurization of a circulating fluidized bed boiler is mostly limestone added in the lower dense phase zone, but the reducing atmosphere in this zone is not conducive to desulfurization, and the calcium oxide generated by the decomposition of limestone will catalyze the conversion of nitrogen-containing volatile matter to NO x When the bed temperature drops to the lower limit of stable operation (about 800℃) during low-load operation, which is lower than the optimal desulfurization temperature of limestone, the in-furnace desulfurization efficiency is significantly reduced. SUMMARY
[0003] The present application is aimed at the problems of low in-furnace desulfurization efficiency of the existing circulating fluidized bed boiler, especially low in-furnace desulfurization efficiency during deep peak-shaving low-load operation, and poor matching of in-furnace desulfurization and post-furnace flue gas desulfurization of the circulating fluidized bed boiler when burning coal with different sulfur contents, and proposes a matching method and system for synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization of a circulating fluidized bed boiler, which significantly improves the in-furnace desulfurization efficiency of the circulating fluidized bed boiler under full load, especially during deep peak-shaving low-load operation, realizes the optimal matching of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization, reduces the investment and operation cost of the desulfurization system of the circulating fluidized bed boiler, and has significant economic and environmental benefits.
[0004] The present application is implemented by the following technical solutions:
[0005] The present application relates to a matching method for synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization of a circulating fluidized bed boiler, which comprises:
[0006] Step 1: Taking the sulfur content of different coal types as the inlet constraint condition and the sulfur dioxide (SO2) emission concentration limit value as the outlet constraint condition, the equivalent sulfur content S ZS and the SO2 emission coefficient of flue gas are calculated according to the coal type According to the formula , the original SO2 emission concentration in the circulating fluidized bed boiler is calculated and determined (mg / m 3 ), the SO2 concentration in the exhaust gas is determined according to the SO2 emission concentration limit value specified by environmental regulations (mg / m 3 ), and the total desulfurization efficiency is calculated, wherein: is the outlet SO2 emission concentration limit value, which is generally ≤ 35 mg / m 3 .
[0007] Step 2: Determine the in-furnace desulfurization efficiency based on the structure and operating parameters of the circulating fluidized bed boiler. Based on total desulfurization efficiency Calculate the required flue gas desulfurization efficiency after the furnace. According to the required flue gas desulfurization efficiency after the furnace. Select a suitable flue gas desulfurization process after the furnace, based on the desulfurization efficiency of different processes. The empirical relationships between these operating parameters determine the calcium-sulfur molar ratio, outlet temperature difference, and liquid-to-gas ratio, specifically including:
[0008] 2.1 In-furnace desulfurization efficiency of circulating fluidized bed boilers Compared with the Ca / S molar ratio in the furnace The relationship between them satisfies: ;
[0009] 2.2 When a humidification and activation flue gas desulfurization system is used after the furnace, the Ca / S molar ratio after the furnace is... outlet temperature distance and The relationship between them satisfies: , 32.26 ;
[0010] 2.3 When a spray drying flue gas desulfurization system is used after the furnace, the Ca / S molar ratio after the furnace is... outlet temperature distance and The relationship between them satisfies: , ;
[0011] 2.4 When a circulating fluidized bed flue gas desulfurization system is used after the furnace, the Ca / S molar ratio after the furnace is... outlet temperature distance and The relationship between them satisfies: , ;
[0012] 2.5 For a limestone-gypsum wet flue gas desulfurization system used after the furnace, when the Ca / S molar ratio after the furnace is 1.03~1.05, the liquid-to-gas ratio is... and The relationship between them satisfies: .
[0013] Step 3, the matching system of the in-furnace enhanced desulfurization of the circulating fluidized bed boiler and the post-furnace flue gas desulfurization is analyzed and optimized in terms of the cost of desulfurization including the load distribution of the in-furnace desulfurization and the post-furnace flue gas desulfurization, and the post-furnace flue gas desulfurization process and the optimal operation parameters meeting the SO2 emission requirement are obtained when the total desulfurization cost of removing each kilogram of SO2 is the lowest, otherwise, the process returns to Step 2 and Step 3 to re-optimize to determine the corresponding post-furnace flue gas desulfurization process and operation parameters.
[0014] The total desulfurization cost includes: ① the in-furnace desulfurization cost of the circulating fluidized bed boiler, ② the flue gas desulfurization cost of the post-furnace humidification and activation flue gas desulfurization technology, the spray drying flue gas desulfurization technology, the circulating fluidized bed flue gas desulfurization technology or the limestone-gypsum wet flue gas desulfurization technology, and ③ other costs.
[0015] The total desulfurization cost is the lowest, which is obtained by comparing the in-furnace desulfurization cost of the circulating fluidized bed boiler with the flue gas desulfurization cost of the post-furnace humidification and activation flue gas desulfurization technology, the spray drying flue gas desulfurization technology, the circulating fluidized bed flue gas desulfurization technology or the limestone-gypsum wet flue gas desulfurization technology.
[0016] The in-furnace desulfurization cost of the circulating fluidized bed boiler includes: the in-furnace limestone cost and the in-furnace desulfurization operation power consumption cost .
[0017] The flue gas desulfurization cost of the post-furnace humidification and activation flue gas desulfurization technology, the spray drying flue gas desulfurization technology or the circulating fluidized bed flue gas desulfurization technology includes: the cost of quicklime or slaked lime , the post-furnace desulfurization operation power consumption cost and the water consumption cost ; the flue gas desulfurization cost of the limestone-gypsum wet flue gas desulfurization technology includes: the limestone cost , the post-furnace desulfurization operation power consumption cost , the water consumption cost , the gypsum income and the waste water treatment cost .
[0018] The other costs include: the depreciation cost , the financial cost , the labor cost and the maintenance cost .
[0019] For the post-furnace flue gas desulfurization process using the humidification and activation flue gas desulfurization technology or the spray drying flue gas desulfurization technology or the circulating fluidized bed flue gas desulfurization technology, the total desulfurization cost of the circulating fluidized bed boiler for removing each kilogram of SO2 is The total desulfurization cost per kilogram of SO2 removed by a circulating fluidized bed boiler is [amount missing]. This is achieved using limestone-gypsum wet flue gas desulfurization technology. Yuan / kg SO2, of which: Cost of limestone inside the furnace, yuan / year; The electricity cost for in-furnace desulfurization operation is RMB / year; Cost of quicklime or hydrated lime, yuan / year; The electricity cost for desulfurization operation after the furnace is RMB / year; Water consumption cost: yuan / year; Revenue from gypsum, yuan / year; The cost of wastewater treatment in wet desulfurization is RMB / year; Equipment depreciation cost, in yuan / year; Financial expenses, RMB / year; Labor costs, RMB / year; Maintenance fee, yuan / year. For S per year Removal amount, kg / year.
[0020] Technical effect
[0021] This invention establishes a matching method for the synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in circulating fluidized bed boilers, with fuel sulfur content as the inlet constraint and SO2 emission concentration limit as the outlet constraint. This method rationally allocates the load of in-furnace desulfurization and post-furnace flue gas desulfurization, maximizing the advantages of efficient and low-cost in-furnace desulfurization in circulating fluidized bed boilers. This results in the lowest investment and operating costs for the SO2 ultra-low emission control system, achieving the best balance between deep desulfurization and ultra-low emission control technology and economy in circulating fluidized bed boilers. Attached Figure Description
[0022] Figure 1 This is a flowchart of the present invention;
[0023] Figures 2-5 This is a schematic diagram of the corresponding matching system used under different circumstances;
[0024] Figure 6 Schematic diagram of limestone desulfurization efficiency in circulating fluidized bed boilers under different Ca / S molar ratios;
[0025] Figure 7 A schematic diagram illustrating the limestone-based staged desulfurization effect inside a circulating fluidized bed boiler.
[0026] Figure: furnace 1, dense phase zone 2, dilute phase zone 3, cyclone 4, standpipe 5, return feeder 6, return leg 7, fuel bin 8, limestone powder bin 9, limestone lower layer conveying pipeline 10, limestone upper layer conveying pipeline 11, coal feeding port 12, lower secondary air port 13, upper secondary air port 14, tail flue 15, calcium hydroxide powder bin 16, in-furnace desulfurization calcium hydroxide conveying pipeline 17, post-furnace desulfurization calcium hydroxide conveying pipeline 18, post-furnace flue gas desulfurization absorption tower 19, atomization device 20, dust collector 21, induced draft fan 22, desulfurized ash bin 23, chimney 24, lime slurry tank 25, process water tank 26, limestone slurry tank 27, oxidizing air fan 28, slurry circulating pump 29, post-furnace limestone powder bin 30, humidification and activation reactor 19-1, spray drying desulfurization absorption tower 19-2, circulating fluidized bed desulfurization reactor 19-3, spray absorption tower 19-4, humidification and activation atomization nozzle 20-1, rotary atomizer 20-2, circulating fluidized bed flue gas desulfurization atomization nozzle 20-3, limestone slurry atomization nozzle 20-4. DETAILED DESCRIPTION
[0027] As shown in Figure 1 , the embodiment relates to a matching method for in-furnace enhanced desulfurization and post-furnace flue gas desulfurization optimization of a circulating fluidized bed boiler, comprising:
[0028] Step 1, taking the sulfur content of different coal types as the inlet constraint condition, taking the SO2 emission concentration limit value as the outlet constraint condition, and calculating the original SO2 emission concentration in the circulating fluidized bed boiler according to the equivalent sulfur content S ZS of the coal type and the SO2 emission coefficient of the flue gas. (mg / m 3 ), determining the SO2 concentration in the exhaust gas according to the SO2 emission concentration limit value specified by the environmental protection regulations (mg / m 3 ), and calculating the total desulfurization efficiency.
[0029] Step 2, determining the in-furnace desulfurization efficiency from the structure and operating parameters of the circulating fluidized bed boiler, calculating the required post-furnace flue gas desulfurization efficiency according to the total desulfurization efficiency. According to the required post-furnace flue gas desulfurization efficiency , selecting a suitable post-furnace flue gas desulfurization process, and determining the calcium-sulfur molar ratio, outlet temperature distance, and liquid-gas ratio operating parameters according to the empirical relationship between the desulfurization efficiency of different post-furnace flue gas desulfurization processes and operating parameters.
[0030] Step 3, the matching system of the in-furnace enhanced desulfurization and the post-furnace flue gas desulfurization is optimized, including the desulfurization cost analysis and optimization of the load distribution of the in-furnace desulfurization and the post-furnace flue gas desulfurization, when the total desulfurization cost of removing each kilogram of SO2 is the lowest, the post-furnace flue gas desulfurization process meeting the SO2 emission requirement and the optimal operation parameter are obtained, otherwise, return to Step 2 and Step 3 to re-optimize to determine the corresponding post-furnace flue gas desulfurization process and operation parameter.
[0031] When the desulfurization efficiency required by the post-furnace flue gas desulfurization process is ≤75%, and the total desulfurization cost of removing each kilogram of SO2 is the lowest, the post-furnace flue gas desulfurization process is adopted Figure 2The matching system of the shown circulating fluidized bed boiler furnace enhanced desulfurization and post-furnace humidification activated flue gas desulfurization synergistic optimization. The system comprises: a hearth 1, a dense phase zone 2, a dilute phase zone 3, a cyclone separator 4, a standpipe 5, a return feeder 6, a return leg 7, a fuel bin 8, a limestone powder bin 9, a limestone lower conveying pipeline 10, a limestone upper conveying pipeline 11, a coal feeding port 12, a lower secondary air port 13, an upper secondary air port 14, a tail flue 15, a lime powder bin 16, a furnace desulfurization lime conveying pipeline 17, a post-furnace desulfurization lime conveying pipeline 18, a humidification activation reactor 19-1, a humidification activation atomizing nozzle 20-1, a dust collector 21, an induced draft fan 22, a desulfurized ash bin 23, a chimney 24, a process water tank 26. Among them: the lower part of the hearth 1 is the dense phase zone 2, and the upper part is the dilute phase zone 3. The input end of the dense phase zone 2 is connected with the limestone lower conveying pipeline 10 and the coal feeding port 12, and the output end is connected with the dilute phase zone 3. The output end of the dilute phase zone 3 is connected with the input end of the cyclone separator 4. The lower output end of the cyclone separator 4 is connected with the input end of the standpipe 5, the output end of the standpipe 5 is connected with the input end of the return feeder 6, and the output end of the return feeder 6 is connected with the dense phase zone 2 through the return leg 7. The output end of the limestone powder bin 9 is connected with the dense phase zone 2 through the limestone lower conveying pipeline 10 and connected with the dilute phase zone 3 through the limestone upper conveying pipeline 11, thereby realizing the staged addition of desulfurizing agent. The addition points of the dense phase zone 2 include the coal feeding port 12 and the lower secondary air port 13; the addition points of the dilute phase zone 3 include the upper secondary air port 14. The upper output end of the cyclone separator 4 is connected with the input end of the tail flue 15, and the output end of the tail flue 15 is directly connected with the input end of the humidification activation reactor 19-1. The output end of the lime powder bin 16 is connected with the coal feeding port 12, the lower secondary air port 13 and the upper secondary air port 14 through the furnace desulfurization lime conveying pipeline 17, and is connected with the humidification activation reactor 19-1 through the post-furnace desulfurization lime conveying pipeline 18. The output end of the process water tank 26 is connected with the inside of the humidification activation reactor 19-1 through the humidification activation atomizing nozzle 20-1, for atomizing and spraying process water. The output end of the humidification activation reactor 19-1 is connected with the input end of the dust collector 21, the upper output end of the dust collector 21 is connected with the input end of the induced draft fan 22, the output end of the induced draft fan 22 is connected with the chimney 24, and the purified flue gas is discharged into the atmosphere. The lower output end of the dust collector 21 is connected with the input end of the desulfurized ash bin 23, for collecting desulfurized ash.
[0032] When the system is running, firstly, fuel is sent into the dense phase zone 2 of the furnace 1 by the fuel bunker 8 through the coal feeding port 12, and at the same time, a part of limestone is added into the dense phase zone 2 through the lower limestone conveying pipeline 10. The fuel in the dense phase zone 2 is combusted, and the generated gas-solid mixture continues to combust and react in the dilute phase zone 3, and at the same time, limestone is added into the dilute phase zone 3 through the upper limestone conveying pipeline 11, so as to realize staged desulfurization. The gas-solid mixture enters the cyclone separator 4 from the outlet of the dilute phase zone 3, and the separated solid particles return to the dense phase zone 2 through the standpipe 5, the return feeder 6 and the return leg 7, so as to maintain stable material circulation. When the bed temperature is lower than 800℃ during low load operation, a part of the lime powder in the lime powder bunker 16 is transported to a certain position or any combination of the coal feeding port 12, the lower secondary air port 13 and the upper secondary air port 14 through the in-furnace desulfurization lime powder conveying pipeline 17 for in-furnace desulfurization, and at the same time, the limestone powder bunker 9, the lower limestone conveying pipeline 10 and the upper limestone conveying pipeline 11 are closed. The flue gas separated by the cyclone separator 4 is transported to the humidification and activation reactor 19-1 through the tail flue 15, and another part of the lime powder in the lime powder bunker 16 is directly sent into the humidification and activation reactor 19-1 through the post-furnace desulfurization lime powder conveying pipeline 18. The process water tank 26 supplies water to the humidification and activation atomizing nozzle 20-1, which is sprayed into the humidification and activation reactor 19-1 after atomization, so as to realize humidification and activation and desulfurization of the flue gas, and further improve the desulfurization efficiency. The reacted flue gas enters the dust collector 21 to remove particulate matter, and the purified flue gas is sent into the chimney 24 by the induced draft fan 22 for emission, and the desulfurized ash collected in the lower part is collected in the desulfurized ash bunker 23 for subsequent treatment and comprehensive utilization.
[0033] When the post-furnace flue gas desulfurization process requires a desulfurization efficiency of 75%< ≤85%, and the total desulfurization cost per kilogram of SO2 removal is the lowest, the post-furnace flue gas desulfurization process is adopted Figure 3The shown system of the circulating fluidized bed boiler in-stoker enhanced desulfurization and post-combustion spray drying flue gas desulfurization synergistic optimization matching system. The system comprises: a hearth 1, a dense phase zone 2, a dilute phase zone 3, a cyclone separator 4, a standpipe 5, a return feeder 6, a return leg 7, a fuel bin 8, a limestone powder bin 9, a limestone lower layer conveying pipeline 10, a limestone upper layer conveying pipeline 11, a coal feeding port 12, a lower secondary air port 13, an upper secondary air port 14, a tail flue 15, a lime powder bin 16, a boiler in-stoker desulfurization lime conveying pipeline 17, a post-combustion desulfurization lime conveying pipeline 18, a spray drying desulfurization absorption tower 19-2, a rotary atomizer 20-2, a dust collector 21, an induced draft fan 22, a desulfurized ash bin 23, a chimney 24, a lime slurry tank 25, a process water tank 26. Among them: the circulating fluidized bed boiler in-stoker enhanced desulfurization part is the same as described above. The output end of the tail flue 15 is connected with the flue gas input end of the spray drying absorption tower 19-2, and the output ends of the lime powder bin 16 and the process water tank 26 are connected with the lime slurry tank 25. The output end of the lime slurry tank 25 is connected with the rotary atomizer 20-2, and the rotary atomizer 20-2 is connected with the top of the spray drying absorption tower 19-2, for atomizing and spraying the lime slurry into the spray drying absorption tower 19-2. The output end of the spray drying absorption tower 19-2 is connected with the dust collector 21, the upper output end of the dust collector 21 is sequentially connected with the induced draft fan 22 and the chimney 24, and the lower output end of the dust collector 21 is connected with the desulfurized ash bin 23. The output end of the spray drying absorption tower 19-2 is connected with the input end of the lime slurry tank 25, for returning part of the desulfurized ash to realize the recycling of the desulfurizing agent.
[0034] The system circulating fluidized bed boiler in-stoker enhanced desulfurization part is the same as described above. The flue gas of the upper outlet of the cyclone separator 4 enters the spray drying absorption tower 19-2 through the tail flue 15. The lime powder in the lime powder bin 16 and the process water supplied by the process water tank 26 are mixed to form a uniform lime slurry. The slurry is atomized by the rotary atomizer 20-2 and sprayed into the spray drying absorption tower 19-2, and the atomized slurry and the flue gas are fully contacted in the tower to complete the post-combustion desulfurization process. The flue gas at the outlet of the spray drying absorption tower 19-2 enters the dust collector 21, and after removing the particulate matter, it is sent into the chimney 24 through the induced draft fan 22; part of the desulfurized ash collected by the dust collector is collected by the desulfurized ash bin 23, and the other part is returned to the lime slurry tank 25 to realize the recycling of the desulfurizing agent and improve the desulfurization efficiency.
[0035] When the required desulfurization efficiency of the post-combustion flue gas desulfurization process is 85% < SO2 removal per kg < 95%, and the total desulfurization cost is the lowest, the post-combustion spray drying flue gas desulfurization process is adopted. Figure 4 The system includes: furnace 1, dense phase zone 2, dilute phase zone 3, cyclone separator 4, standpipe 5, return feeder 6, return leg 7, fuel bin 8, limestone powder bin 9, limestone lower layer conveying pipeline 10, limestone upper layer conveying pipeline 11, coal feeding port 12, lower secondary air port 13, upper secondary air port 14, tail flue 15, lime powder bin 16, in-furnace desulfurization lime conveying pipeline 17, post-furnace desulfurization lime conveying pipeline 18, circulating fluidized bed flue gas desulfurization reactor 19-3, circulating fluidized bed flue gas desulfurization atomizing nozzle 20-3, dust collector 21, induced draft fan 22, desulfurized ash bin 23, chimney 24, process water tank 26. The circulating fluidized bed boiler in-furnace enhanced desulfurization part is the same as the aforementioned. The output end of the tail flue 15 is connected with the bottom input end of the circulating fluidized bed flue gas desulfurization reactor 19-3. The output end of the lime powder bin 16 is connected with the side input end of the circulating fluidized bed flue gas desulfurization reactor 19-3 through the post-furnace desulfurization lime conveying pipeline 18. The output end of the process water tank 26 is connected with the input end of the circulating fluidized bed flue gas desulfurization atomizing nozzle 20-3, and the output end of the circulating fluidized bed flue gas desulfurization atomizing nozzle 20-3 is connected with the other side input end of the circulating fluidized bed flue gas desulfurization reactor 19-3. The output end of the circulating fluidized bed flue gas desulfurization reactor 19-3 is connected with the input end of the dust collector 21. The upper flue gas output end of the dust collector 21 is connected with the induced draft fan 22 and the chimney 24 in sequence. The lower output end of the dust collector 21 is connected with the desulfurized ash bin 23 on one hand, and connected with the circulating fluidized bed flue gas desulfurization reactor 19-3 through the ash return pipeline on the other hand.
[0036] The circulating fluidized bed boiler in-furnace enhanced desulfurization part of the system is the same as the aforementioned. The flue gas separated by the circulating fluidized bed boiler cyclone separator 4 enters the circulating fluidized bed flue gas desulfurization reactor 19-3 through the tail flue 15. The lime powder in the lime powder bin 16 is sent into the circulating fluidized bed flue gas desulfurization reactor 19-3 through the post-furnace desulfurization lime conveying pipeline 18, and the water in the process water tank 26 is atomized and sprayed into the circulating fluidized bed flue gas desulfurization reactor 19-3 through the circulating fluidized bed flue gas desulfurization atomizing nozzle 20-3. The flue gas, lime powder and atomized water droplets are fully mixed and contacted in the reactor and react, so as to remove SO2 in the flue gas. The reacted flue gas carrying fine particle desulfurized ash enters the dust collector 21, and the purified flue gas is sent into the chimney 24 through the induced draft fan 22 for emission. Part of the desulfurized ash is collected and sent into the desulfurized ash bin 23, and the other part is returned to the circulating fluidized bed flue gas desulfurization reactor 19-3 through the return pipeline for recycling, so as to improve the lime recycling rate and desulfurization efficiency.
[0037] When the post-furnace flue gas desulfurization process requires a desulfurization efficiency of > 95%, and the total desulfurization cost per kilogram of SO2 removed is the lowest, the system is adopted Figure 5The system shown is a matching system for the synergistic optimization of in-furnace enhanced desulfurization and post-furnace limestone-gypsum wet flue gas desulfurization in a circulating fluidized bed boiler. The system includes: furnace 1, dense phase zone 2, dilute phase zone 3, cyclone separator 4, riser 5, return feeder 6, return feed leg 7, fuel bin 8, limestone powder bin 9, lower limestone conveying pipeline 10, upper limestone conveying pipeline 11, coal feed inlet 12, lower secondary air outlet 13, upper secondary air outlet 14, tail flue 15, hydrated lime powder bin 16, in-furnace desulfurization hydrated lime conveying pipeline 17, spray absorption tower 19-4, limestone slurry atomizing nozzle 20-4, dust collector 21, induced draft fan 22, desulfurization ash bin 23, chimney 24, process water tank 26, oxidation fan 27, slurry circulation pump 28, post-furnace limestone powder bin 29, and limestone slurry tank 30. The in-furnace enhanced desulfurization section of the circulating fluidized bed boiler is the same as described above. The output end of the tail flue 15 is connected to the input end of the dust collector 21. The upper output end of the dust collector 21 is connected to the flue gas inlet of the spray absorption tower 19-4, and the lower output end of the dust collector 21 is connected to the ash silo 23. The output ends of the process water tank 26 and the limestone powder silo 29 are connected to the input end of the limestone slurry tank 30. The output end of the limestone slurry tank 30 is connected to the bottom input end of the spray absorption tower 19-4. The input end of the slurry circulation pump 28 is connected to the bottom slurry pool of the spray absorption tower 19-4, and the output end of the slurry circulation pump 28 is connected to the limestone slurry atomizing nozzle 20-4. The output end of the oxidation fan 27 is connected to the bottom slurry pool of the spray absorption tower 19-4. The upper output end of the spray absorption tower 19-4 is connected to the input end of the induced draft fan 22, and the output end of the induced draft fan 22 is connected to the chimney 24.
[0038] The enhanced desulfurization section of the circulating fluidized bed boiler in this system is the same as described above. The flue gas separated by the cyclone separator 4 of the circulating fluidized bed boiler enters the dust collector 21 through the tail flue 15, and then enters the spray absorption tower 19-4 after dust removal. Process water from the process water tank 26 and limestone powder from the limestone powder silo 29 are fed into the limestone slurry tank 30 to form limestone slurry. This slurry is then pumped to the upper part of the spray absorption tower 19-4 by the slurry circulation pump 28 and sprayed into the tower through the limestone slurry atomizing nozzles 20-4. Simultaneously, the limestone slurry fully contacts the flue gas, absorbing SO2 to generate calcium sulfite. At the same time, the oxidation fan 27 introduces air into the slurry pool at the bottom of the spray absorption tower 19-4, forcibly oxidizing and crystallizing the calcium sulfite to generate gypsum. The desulfurized flue gas from the spray absorption tower 19-4 is then heated by the flue gas heater before entering the induced draft fan 22 and being discharged through the chimney 24.
[0039] Through specific practical experiments, such as Figure 6 As shown, in a circulating fluidized bed boiler with a bed temperature of 850℃ and an in-furnace Ca / S molar ratio of [missing information], When the Ca / S molar ratio is between 0 and 3.5, the desulfurization efficiency in the furnace increases rapidly with the increase of the Ca / S molar ratio. When the Ca / S molar ratio in the furnace is greater than 2.5, the desulfurization efficiency in the furnace decreases. The efficiency tends to stabilize. Experimental data fitting indicates that the in-furnace desulfurization efficiency... Compared with the Ca / S molar ratio in the furnace The empirical relationship between them is: .
[0040] Through specific practical experiments, such as Figure 7 As shown, under the same circulating fluidized bed boiler conditions of 850℃ and Ca / S molar ratio of 2, when limestone is added alone to the coal feed inlet 12 in the lower dense phase zone of the furnace (i.e., without limestone grading), the in-furnace desulfurization efficiency is 92%. When limestone is graded and added to both the coal feed inlet 12 in the lower dense phase zone and the upper secondary tuyer 14 in the upper dilute phase zone, the in-furnace desulfurization efficiency is 95% when the mass ratio of limestone added to the coal feed inlet 12 in the lower dense phase zone to that added to the upper secondary tuyer 14 in the upper dilute phase zone is 3:1, an increase of 3 percentage points. When the mass ratio of limestone added to the coal feed inlet 12 in the lower dense phase zone to that added to the upper secondary tuyer 14 in the upper dilute phase zone is 1:1 and 1:3, the in-furnace desulfurization efficiencies are 88% and 84%, respectively. Therefore, when the desulfurization bed temperature in the circulating fluidized bed boiler is 850℃ and the Ca / S molar ratio is 2, the desulfurization efficiency in the furnace is significantly improved to 95% by using the aforementioned in-furnace limestone graded addition and graded desulfurization system and setting the mass ratio of limestone added at the dense phase zone coal feed port 12 to the upper secondary air port 14 of the dilute phase zone to 3:1.
[0041] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.
Claims
1. A matching method for optimizing the cooperation of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler, characterized in that, It comprises: Step 1, taking the sulfur content of different coal as the inlet constraint condition, and taking the ultra-low emission concentration limit of sulfur dioxide as the outlet constraint condition, the total desulfurization efficiency is calculated ; Step 2, determine the desulfurization efficiency in the furnace from the circulating fluidized bed boiler structure and operation parameters , according to the total desulfurization efficiency Calculate the required post-furnace flue gas desulfurization efficiency And determine the calcium-sulfur molar ratio, outlet temperature distance, liquid-gas ratio operation parameters; Step 3, the matching system of the intensified desulfurization in the circulating fluidized bed boiler and the coordinated optimization of the flue gas desulfurization after the boiler is subjected to desulfurization cost analysis and optimization including load distribution of the desulfurization in the boiler and the flue gas desulfurization after the boiler, when the total desulfurization cost of removing each kilogram of SO2 is the lowest, the flue gas desulfurization process after the boiler meeting the SO2 emission requirement and the optimal operation parameters are obtained, otherwise, steps 2 and 3 are returned to re-optimize to determine the corresponding flue gas desulfurization process after the boiler and the operation parameters; The total desulfurization cost comprises: ① the desulfurization cost in the circulating fluidized bed boiler, ② the flue gas desulfurization cost of the humidification and activation flue gas desulfurization technology, the spray drying flue gas desulfurization technology, the circulating fluidized bed flue gas desulfurization technology or the limestone-gypsum wet flue gas desulfurization technology and ③ other costs; The total desulfurization cost is the lowest, which is obtained by comparing the desulfurization cost in the circulating fluidized bed boiler and the flue gas desulfurization cost of the humidification and activation flue gas desulfurization technology, the spray drying flue gas desulfurization technology, the circulating fluidized bed flue gas desulfurization technology or the limestone-gypsum wet flue gas desulfurization technology.
2. The method according to claim 1, characterized in that, The step 1 is specifically: according to the conversion sulfur content S of the coal ZS and the emission coefficient of SO2 in the flue gas According to the formula The original SO2 emission concentration in the circulating fluidized bed boiler is determined (mg / m 3 ), the SO2 concentration in the flue gas is determined according to the SO2 emission concentration limit value stipulated in the environmental protection regulations The total desulfurization efficiency is calculated , wherein: is the outlet SO2 emission concentration limit value.
3. The method according to claim 1, wherein the method is characterized in that, The calcium-sulfur molar ratio operating parameter is determined according to the required flue gas desulfurization efficiency after the furnace A suitable flue gas desulfurization process after the furnace is selected, and the calcium-sulfur molar ratio operating parameter is determined according to the desulfurization efficiency of different flue gas desulfurization processes after the furnace The calcium-sulfur molar ratio operating parameter is determined according to the empirical relationship with the operating parameter.
4. The method according to claim 3, characterized in that, The step 2 specifically comprises: 2.1 Circulating fluidized bed boiler in-furnace desulfurization efficiency The relationship between the in-furnace Ca / S molar ratio satisfies: ; 2.2 When the wet activated flue gas desulfurization system is used after the furnace, the Ca / S molar ratio after the furnace , the relationship between the outlet temperature distance and satisfies: , 32.26 ; 2.3 When the spray drying flue gas desulfurization system is used after the furnace, the Ca / S mole ratio after the furnace , the outlet temperature distance and satisfy the relationship: , ; 2.4 When the circulating fluidized bed flue gas desulfurization system is used after the furnace, the Ca / S mole ratio after the furnace , the relationship between the outlet temperature distance and satisfies: , ; 2.5 For the limestone-gypsum wet flue gas desulfurization system after the furnace, when the Ca / S molar ratio after the furnace is 1.03-1.05, the relationship between the liquid-gas ratio and satisfies: .
5. The method according to claim 1, wherein the method is characterized in that, The circulating fluidized bed boiler in-furnace desulfurization cost includes: in-furnace limestone cost and in-furnace desulfurization operation power consumption cost ; The flue gas desulfurization cost of the post-combustion humidification activated flue gas desulfurization technology, the spray drying flue gas desulfurization technology or the circulating fluidized bed flue gas desulfurization technology includes: cost of quicklime or slaked lime , post-combustion desulfurization operation power consumption cost and water consumption cost ; the flue gas desulfurization cost of the limestone-gypsum wet flue gas desulfurization technology includes: cost of limestone , post-combustion desulfurization operation power consumption cost , water consumption cost , gypsum income and waste water treatment cost ; The other expenses include: depreciation expenses , financial expenses , labor expenses and repair expenses ; For the flue gas desulfurization process after the furnace, the total desulfurization cost of circulating fluidized bed boiler to remove per kg of SO2 is , yuan / kg SO2; for the flue gas desulfurization process after the furnace, the total desulfurization cost of circulating fluidized bed boiler to remove per kg of SO2 is , yuan / kg SO2, wherein: is the cost of limestone in the furnace, yuan / year; is the cost of electricity consumption in the desulfurization operation in the furnace, yuan / year; is the cost of quicklime or slaked lime, yuan / year; is the cost of electricity consumption in the desulfurization operation after the furnace, yuan / year; is the cost of water consumption, yuan / year; is the income of gypsum, yuan / year; is the cost of wastewater treatment in the wet desulfurization, yuan / year; is the cost of equipment depreciation, yuan / year; is the cost of finance, yuan / year; is the cost of labor, yuan / year; is the cost of maintenance, yuan / year, is the annual S removal amount, kg / year.
6. The method for matching optimization of in-furnace desulfurization and post-furnace flue gas desulfurization according to any one of claims 1-4, characterized in that, The required desulfurization efficiency of the flue gas desulfurization process after the furnace When the SO2 removal rate is ≤75% and the total desulfurization cost per kilogram of SO2 is lowest, a matching system of in-furnace enhanced desulfurization and post-furnace humidification and activation flue gas desulfurization in a circulating fluidized bed boiler is adopted. Specifically, this system includes: furnace, dense phase zone, dilute phase zone, cyclone separator, riser, return feeder, return feed leg, fuel bin, limestone powder bin, lower limestone conveying pipeline, upper limestone conveying pipeline, coal feed inlet, lower secondary air inlet, upper secondary air inlet, tail flue, hydrated lime powder bin, in-furnace desulfurization hydrated lime conveying pipeline, and post-furnace desulfurization hydrated lime conveying pipeline. The furnace consists of a humidification and activation reactor, humidification and activation atomizing nozzles, a dust collector, an induced draft fan, a desulfurization ash silo, a chimney, and a process water tank. The lower part of the furnace is a dense phase zone, and the upper part is a dilute phase zone. The input end of the dense phase zone is connected to the lower limestone conveying pipeline and the coal feed inlet, and the output end is connected to the dilute phase zone. The output end of the dilute phase zone is connected to the input end of a cyclone separator. The lower output end of the cyclone separator is connected to the input end of a riser. The output end of the riser is connected to the input end of a return feeder. The output end of the return feeder is connected to the dense phase zone via a return feed leg. (The limestone powder...) The output ends of the silo are connected to the dense phase zone via the lower limestone conveying pipeline and to the dilute phase zone via the upper limestone conveying pipeline, thereby achieving staged addition of desulfurizing agent. The addition points in the dense phase zone include the coal feed inlet and the lower secondary air inlet; the addition point in the dilute phase zone includes the upper secondary air inlet. The upper output end of the cyclone separator is connected to the input end of the tail flue, and the output end of the tail flue is directly connected to the input end of the humidification and activation reactor. The output end of the hydrated lime powder silo is connected to the coal feed inlet, the lower secondary air inlet, and the upper secondary air inlet via the in-furnace desulfurization hydrated lime conveying pipeline. The upper secondary air outlet is connected, and on the other hand, it is connected to the humidification and activation reactor through the desulfurization slaked lime conveying pipeline after the furnace. The output end of the process water tank is connected to the inside of the humidification and activation reactor through the humidification and activation atomizing nozzle for atomizing and spraying process water. The output end of the humidification and activation reactor is connected to the input end of the dust collector. The upper output end of the dust collector is connected to the input end of the induced draft fan. The output end of the induced draft fan is connected to the chimney to discharge the purified flue gas into the atmosphere. The lower output end of the dust collector is connected to the input end of the desulfurization ash silo for collecting desulfurization ash. The matching system of the intensified desulfurization in the circulating fluidized bed boiler and the coordinated optimization of the humidification and activation flue gas desulfurization after the boiler firstly sends the fuel into the dense phase zone of the furnace through the coal feeding port from the fuel bin, and a part of the limestone is added into the dense phase zone through the lower limestone conveying pipeline, the fuel in the dense phase zone is combusted, and the generated gas-solid mixture enters the dilute phase zone for further combustion and reaction, and the limestone is added into the dilute phase zone through the upper limestone conveying pipeline to realize the staged desulfurization, the gas-solid mixture from the dilute phase zone outlet enters the cyclone separator, and the separated solid particles return to the dense phase zone through the standpipe, the return feeder and the return leg to maintain the stable material circulation. When the bed temperature is lower than 800 DEG C during the low load operation, a part of the lime powder in the lime powder bin is conveyed to the coal feeding port, the lower secondary air port and the upper secondary air port or any combination thereof through the in-furnace desulfurization lime powder conveying pipeline for in-furnace desulfurization, and the limestone powder bin, the lower limestone conveying pipeline and the upper limestone conveying pipeline are closed, the flue gas separated by the cyclone separator is conveyed to the humidification and activation reactor through the tail flue, another part of the lime powder in the lime powder bin is directly sent into the humidification and activation reactor through the post-desulfurization lime powder conveying pipeline, the process water tank supplies water to the humidification and activation atomizing nozzle, the water is sprayed into the humidification and activation reactor after atomization to realize the humidification and activation and desulfurization of the flue gas and further improve the desulfurization efficiency, the reacted flue gas enters the dust remover to remove the particulate matters, the purified flue gas is sent into the chimney through the induced draft fan for emission, and the desulfurized ash collected in the lower part is collected in the desulfurized ash bin for subsequent treatment and comprehensive utilization.
7. The method for matching optimization of in-furnace desulfurization and post-furnace flue gas desulfurization according to any one of claims 1-4, characterized in that, When the required desulfurization efficiency of the flue gas desulfurization process behind the furnace is 75%< ≤85%, and the total desulfurization cost per kilogram of SO2 is the lowest, a matching system of the in-furnace enhanced desulfurization of the circulating fluidized bed boiler and the flue gas desulfurization after the furnace by the spray drying method is adopted, which specifically comprises: a furnace, a dense phase zone, a dilute phase zone, a cyclone separator, a standpipe, a return feeder, a return leg, a fuel bin, a limestone powder bin, a lower limestone conveying pipeline, an upper limestone conveying pipeline, a coal feeding port, a lower secondary air port, an upper secondary air port, a tail flue, a lime powder bin, an in-furnace desulfurization lime conveying pipeline, an after-furnace desulfurization lime conveying pipeline, a spray drying desulfurization absorption tower, a rotary atomizer, a dust collector, an induced draft fan, a desulfurization ash bin, a chimney, a lime slurry tank, and a process water tank, wherein: the lower part of the furnace is the dense phase zone, and the upper part is the dilute phase zone; the input end of the dense phase zone is connected with the lower limestone conveying pipeline and the coal feeding port, and the output end is connected with the dilute phase zone; the output end of the dilute phase zone is connected with the input end of the cyclone separator; the lower output end of the cyclone separator is connected with the input end of the standpipe; the output end of the standpipe is connected with the input end of the return feeder; the output end of the return feeder is connected with the dense phase zone through the return leg; the output end of the limestone powder bin is connected with the dense phase zone through the lower limestone conveying pipeline and connected with the dilute phase zone through the upper limestone conveying pipeline, so as to realize the staged addition of the desulfurizing agent; the addition points of the dense phase zone include the coal feeding port and the lower secondary air port; the addition point of the dilute phase zone includes the upper secondary air port; the upper output end of the cyclone separator is connected with the input end of the tail flue; the output end of the tail flue is connected with the flue gas input end of the spray drying absorption tower; the output ends of the lime powder bin and the process water tank are connected with the lime slurry tank; the output end of the lime slurry tank is connected with the rotary atomizer; the rotary atomizer is connected with the top of the spray drying absorption tower, for atomizing and spraying the lime slurry into the spray drying absorption tower; the output end of the spray drying absorption tower is connected with the dust collector; the upper output end of the dust collector is sequentially connected with the induced draft fan and the chimney; the lower output end of the dust collector is connected with the desulfurization ash bin; the output end of the spray drying absorption tower is connected with the input end of the lime slurry tank, for returning part of the desulfurization ash to realize the recycling of the desulfurizing agent. In the matching system of the circulating fluidized bed boiler in-strengthened desulfurization and post-combustion spray drying flue gas desulfurization, the flue gas from the upper outlet of the cyclone separator enters the spray drying absorption tower through the tail flue, the slaked lime powder in the slaked lime powder bin is mixed with the process water supplied from the process water tank to form uniform lime slurry, the slurry is atomized by the rotary atomizer and sprayed into the spray drying absorption tower, the atomized slurry and the flue gas are fully contacted in the tower to complete the post-combustion desulfurization process, the flue gas from the outlet of the spray drying absorption tower enters the dust collector, and after removing the particulate matters, is sent into the chimney by the induced draft fan; the desulfurization ash collected by the dust collector is partly collected by the desulfurization ash bin, and the other part is returned to the lime slurry tank to realize the recycling of the desulfurizer and improve the desulfurization efficiency.
8. The method for matching optimization of in-furnace desulfurization and post-furnace flue gas desulfurization according to any one of claims 1-4, characterized in that, When the required desulfurization efficiency of the flue gas desulfurization process after the furnace is 85%< ≤95%, and the total desulfurization cost per kilogram of SO2 is the lowest, a matching system of in-furnace enhanced desulfurization and post-furnace circulating fluidized bed flue gas desulfurization is adopted, which specifically comprises: a furnace, a dense phase zone, a dilute phase zone, a cyclone separator, a standpipe, a return feeder, a return leg, a fuel bin, a limestone powder bin, a lower limestone conveying pipeline, an upper limestone conveying pipeline, a coal feeding port, a lower secondary air port, an upper secondary air port, a tail flue, a lime powder bin, an in-furnace desulfurization lime conveying pipeline, a post-furnace desulfurization lime conveying pipeline, a circulating fluidized bed flue gas desulfurization reactor, a circulating fluidized bed flue gas desulfurization atomizing nozzle, a dust collector, an induced draft fan, a desulfurized ash bin, a chimney, and a process water tank, wherein: the lower part of the furnace is the dense phase zone, and the upper part is the dilute phase zone; the input end of the dense phase zone is connected with the lower limestone conveying pipeline and the coal feeding port, and the output end is connected with the dilute phase zone; the output end of the dilute phase zone is connected with the input end of the cyclone separator; the lower output end of the cyclone separator is connected with the input end of the standpipe; the output end of the standpipe is connected with the input end of the return feeder; the output end of the return feeder is connected with the dense phase zone through the return leg; the output end of the limestone powder bin is connected with the dense phase zone through the lower limestone conveying pipeline and connected with the dilute phase zone through the upper limestone conveying pipeline, thereby realizing the staged addition of desulfurizing agents; the addition points of the dense phase zone include the coal feeding port and the lower secondary air port; the addition point of the dilute phase zone includes the upper secondary air port; the upper output end of the cyclone separator is connected with the input end of the tail flue; the output end of the tail flue is connected with the bottom input end of the circulating fluidized bed flue gas desulfurization reactor; the output end of the lime powder bin is connected with the side input end of the circulating fluidized bed flue gas desulfurization reactor through the post-furnace desulfurization lime conveying pipeline; the output end of the process water tank is connected with the input end of the circulating fluidized bed flue gas desulfurization atomizing nozzle; the output end of the circulating fluidized bed flue gas desulfurization atomizing nozzle is connected with the other side input end of the circulating fluidized bed flue gas desulfurization reactor; the output end of the circulating fluidized bed flue gas desulfurization reactor is connected with the input end of the dust collector; the upper flue gas output end of the dust collector is sequentially connected with the induced draft fan and the chimney; the lower output end of the dust collector is connected with the desulfurized ash bin on one hand and connected with the circulating fluidized bed flue gas desulfurization reactor through an ash return pipeline on the other hand. In the matching system of the circulating fluidized bed boiler in-strengthened desulfurization and post-combustion circulating fluidized bed flue gas desulfurization, the flue gas separated by the cyclone separator of the circulating fluidized bed boiler enters the circulating fluidized bed flue gas desulfurization reactor through the tail flue, the slaked lime powder in the slaked lime powder bin is sent into the circulating fluidized bed flue gas desulfurization reactor through the post-combustion desulfurization slaked lime conveying pipeline, the water in the process water tank is atomized and sprayed into the circulating fluidized bed flue gas desulfurization reactor through the circulating fluidized bed flue gas desulfurization atomizing nozzle, the flue gas, the slaked lime powder and the atomized water droplets are fully mixed, contacted and reacted in the reactor to remove SO2 in the flue gas, the reacted flue gas carrying fine particulate desulfurization ash enters the dust collector, the purified flue gas is sent into the chimney by the induced draft fan, and part of the desulfurization ash is collected and sent into the desulfurization ash bin, and the other part is returned to the circulating fluidized bed flue gas desulfurization reactor through the return pipeline to realize recycling and improve the recycling rate of the lime and the desulfurization efficiency.
9. The method for matching optimization of in-furnace desulfurization and post-furnace flue gas desulfurization according to any one of claims 1-4, characterized in that, The required desulfurization efficiency of the flue gas desulfurization process after the furnace When the desulfurization rate is >95% and the total desulfurization cost per kilogram of SO2 removed is lowest, a matching system of in-furnace enhanced desulfurization and post-furnace limestone-gypsum wet flue gas desulfurization in a circulating fluidized bed boiler is adopted. Specifically, this system includes: furnace, dense phase zone, dilute phase zone, cyclone separator, riser, return feeder, return feed leg, fuel bin, limestone powder bin, lower limestone conveying pipeline, upper limestone conveying pipeline, coal feed inlet, lower secondary air inlet, upper secondary air inlet, tail flue, hydrated lime powder bin, in-furnace desulfurization hydrated lime conveying pipeline, spray absorption tower, and limestone powder bin. The furnace includes limestone slurry atomizing nozzles, dust collectors, induced draft fans, desulfurization ash silos, chimneys, process water tanks, oxidation fans, slurry circulation pumps, limestone powder silos after the furnace, and limestone slurry tanks. The lower part of the furnace is a dense phase zone, and the upper part is a dilute phase zone. The input end of the dense phase zone is connected to the lower limestone conveying pipeline and the coal feed inlet, and the output end is connected to the dilute phase zone. The output end of the dilute phase zone is connected to the input end of a cyclone separator. The lower output end of the cyclone separator is connected to the input end of a riser. The output end of the riser is connected to the input end of a return feeder. The return feeder... The outlet is connected to the dense phase zone via a return leg. The outlet of the limestone powder silo is connected to the dense phase zone via a lower limestone conveying pipeline and to the dilute phase zone via an upper limestone conveying pipeline, thus achieving staged addition of desulfurizing agent. The addition points in the dense phase zone include the coal feed inlet and the lower secondary air outlet; the addition point in the dilute phase zone includes the upper secondary air outlet. The upper outlet of the cyclone separator is connected to the input end of the tail flue, the outlet of the tail flue is connected to the input end of the dust collector, and the upper outlet of the dust collector is connected to the flue gas inlet of the spray absorption tower. The lower output end of the dust collector is connected to the ash silo; the output ends of the process water tank and the limestone powder silo behind the furnace are connected to the input end of the limestone slurry tank; the output end of the limestone slurry tank is connected to the bottom input end of the spray absorption tower; the input end of the slurry circulation pump is connected to the slurry pool at the bottom of the spray absorption tower; the output end of the slurry circulation pump is connected to the limestone slurry atomizing nozzle; the output end of the oxidation blower is connected to the slurry pool at the bottom of the spray absorption tower; the upper output end of the spray absorption tower is connected to the input end of the induced draft fan; and the output end of the induced draft fan is connected to the chimney. In the matching system of the circulating fluidized bed boiler in-strengthened desulfurization and post-combustion limestone-gypsum wet flue gas desulfurization, the flue gas separated by the cyclone separator of the circulating fluidized bed boiler enters the dust collector through the tail flue, the flue gas after dust removal enters the spray absorption tower, the process water in the process water tank and the limestone powder in the post-combustion limestone powder bin are sent into the limestone slurry tank to prepare limestone slurry, the slurry is delivered to the upper part of the spray absorption tower by the slurry circulating pump, and is sprayed into the spray absorption tower through the limestone slurry atomizing nozzle to fully contact with the flue gas to absorb SO2 and generate calcium sulfite, the air is introduced into the slurry pool at the bottom of the spray absorption tower by the oxidation fan to forcibly oxidize and crystallize the calcium sulfite to generate gypsum, and the flue gas after desulfurization of the spray absorption tower is heated by the flue gas heater to increase the temperature, enters the induced draft fan, and is discharged into the chimney.