Method and system for matching of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization optimization of circulating fluidized bed boiler

Abstract

A kind of matching method and system of circulating fluidized bed boiler in-strengthened desulfurization and post-combustion flue gas desulfurization synergistic optimization, with sulfur content of different coal as inlet constraint condition, with sulfur dioxide emission concentration limit as outlet constraint condition, total desulfurization efficiency is calculated, then in-strengthened desulfurization efficiency of circulating fluidized bed boiler structure and operating parameters is determined, according to total desulfurization efficiency, post-combustion flue gas desulfurization efficiency needed to be reached is calculated, and calcium-sulfur molar ratio, outlet temperature distance, liquid-gas ratio operating parameters are determined, then circulating fluidized bed boiler in-strengthened desulfurization and post-combustion flue gas desulfurization synergistic optimization matching system is analyzed and optimized, including in-strengthened desulfurization and post-combustion flue gas desulfurization load distribution, when total desulfurization cost of removing each kilogram of SO2 is lowest, post-combustion flue gas desulfurization process and optimal operating parameters meeting SO2 emission requirements are obtained.The present application realizes optimal matching of circulating fluidized bed boiler in-strengthened desulfurization and post-combushion flue gas desulfurization, reduces investment and operating cost of circulating fluidized bed boiler desulfurization system, and has significant economic and environmental benefits.

Description

Technical Field

[0001] This invention relates to a technology in the field of thermal power generation, specifically a matching method and system for the synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler. Background Technology

[0002] In existing circulating fluidized bed boilers, in-furnace desulfurization often involves adding limestone in the lower dense phase zone. However, the reducing atmosphere in this zone is not conducive to desulfurization, and the calcium oxide generated from the decomposition of limestone can catalyze the conversion of nitrogen-containing volatiles into NO. x Conversion. When operating at low load, the bed temperature drops to the lower limit of stable operation (around 800℃), which is lower than the optimal desulfurization temperature of limestone, resulting in a significant decrease in desulfurization efficiency in the furnace. Summary of the Invention

[0003] This invention addresses the problems of low in-furnace desulfurization efficiency in existing circulating fluidized bed (CFB) boilers, particularly during deep peak shaving and low-load operation, and poor matching between in-furnace desulfurization and post-furnace flue gas desulfurization when burning coals with different sulfur contents. It proposes a matching method and system for synergistic optimization of enhanced in-furnace desulfurization and post-furnace flue gas desulfurization in CFB boilers. This significantly improves the in-furnace desulfurization efficiency of CFB boilers under full-load, especially deep peak shaving and low-load operation conditions, achieving optimal matching between enhanced in-furnace desulfurization and post-furnace flue gas desulfurization, reducing the investment and operating costs of CFB boiler desulfurization systems, and demonstrating significant economic and environmental benefits.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a matching method for the synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler, comprising:

[0006] Step 1: Using the sulfur content of different coal types as the inlet constraint and the sulfur dioxide (SO2) emission concentration limit as the outlet constraint, calculate the sulfur content S of the coal type. ZS And the emission coefficient of SO2 in flue gas According to the formula Calculate and determine the initial SO2 emission concentration in the circulating fluidized bed boiler. (mg / m 3 The SO2 concentration in the flue gas is determined according to the SO2 emission concentration limits stipulated by environmental protection regulations. (mg / m 3 The total desulfurization efficiency was calculated. ,in: The SO2 emission concentration limit at the outlet is generally ≤35 mg / m³. 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: Perform desulfurization cost analysis and optimization on the matching system of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in circulating fluidized bed boilers, including the load distribution of in-furnace desulfurization and post-furnace flue gas desulfurization. When the total desulfurization cost per kilogram of SO2 removed is the lowest, the post-furnace flue gas desulfurization process and optimal operating parameters that meet SO2 emission requirements are obtained. Otherwise, return to Step 2 and Step 3 to re-optimize and determine the corresponding post-furnace flue gas desulfurization process and operating parameters.

[0014] The total desulfurization cost includes: ① the cost of in-furnace desulfurization in circulating fluidized bed boilers; ② the cost of flue gas desulfurization using post-furnace humidification and activation technology, spray drying technology, circulating fluidized bed technology, or limestone-gypsum wet flue gas desulfurization technology; and ③ other costs.

[0015] The lowest total desulfurization cost is obtained by comparing the cost of in-furnace desulfurization in circulating fluidized bed boilers with the cost of flue gas desulfurization using post-furnace humidification activation technology, spray drying technology, circulating fluidized bed technology, or limestone-gypsum wet flue gas desulfurization technology.

[0016] The aforementioned in-furnace desulfurization costs for circulating fluidized bed boilers include: in-furnace limestone costs. Electricity consumption for in-furnace desulfurization operation .

[0017] The flue gas desulfurization costs mentioned above, including those for post-furnace humidification and activation flue gas desulfurization technology, spray drying flue gas desulfurization technology, or circulating fluidized bed flue gas desulfurization technology, include the cost of quicklime or hydrated lime. Electricity consumption cost of desulfurization operation after furnace and water consumption costs The cost of flue gas desulfurization (FGD) using limestone-gypsum wet FGD technology includes: limestone costs. Electricity consumption costs for desulfurization operation after furnace Water consumption costs gypsum revenue and wastewater treatment costs .

[0018] Other expenses include: depreciation. Financial expenses Labor costs and repair costs .

[0019] For flue gas desulfurization processes after the furnace, whether humidification activation flue gas desulfurization technology, spray drying flue gas desulfurization technology, or circulating fluidized bed flue gas desulfurization technology is used, the total desulfurization cost per kilogram of SO2 removed by a circulating fluidized bed boiler is as follows: The total desulfurization cost per kilogram of SO2 removed by a circulating fluidized bed boiler using limestone-gypsum wet flue gas desulfurization technology is [amount missing]. 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] In the diagram: 1. Furnace; 2. Dense Phase Zone; 3. Dilute Phase Zone; 4. Cyclone Separator; 5. Riser; 6. Return Feeder; 7. Return Feed Leg; 8. Fuel Bin; 9. Limestone Powder Bin; 10. Lower Limestone Conveying Pipeline; 11. Upper Limestone Conveying Pipeline; 12. Coal Feed Inlet; 13. Lower Secondary Air Inlet; 14. Upper Secondary Air Inlet; 15. Tail Flue; 16. Slaked Lime Powder Bin; 17. In-furnace Desulfurization Slaked Lime Conveying Pipeline; 18. Post-furnace Desulfurization Slaked Lime Conveying Pipeline; 19. Post-furnace Flue Gas Desulfurization Absorption Tower; 20. Atomizing Device; 21. Dust Collector; 22. Exhaust Fan. 2. Desulfurization ash silo 23. Chimney 24. Lime slurry tank 25. Process water tank 26. Limestone slurry tank 27. Oxidation blower 28. Slurry circulation pump 29. Post-furnace limestone powder silo 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 atomizing nozzle 20-1. Rotary atomizer 20-2. Circulating fluidized bed flue gas desulfurization atomizing nozzle 20-3. Limestone slurry atomizing nozzle 20-4. Detailed Implementation

[0027] like Figure 1 As shown, this embodiment relates to a matching method for synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler, including:

[0028] Step 1: Using the sulfur content of different coal types as the inlet constraint and the SO2 emission concentration limit as the outlet constraint, calculate the sulfur content S based on the converted sulfur content of the coal type. ZS And the emission coefficient of SO2 in flue gas Calculate and determine the initial SO2 emission concentration in the circulating fluidized bed boiler. (mg / m 3 The SO2 concentration in the flue gas is determined according to the SO2 emission concentration limits stipulated by environmental protection regulations. (mg / m 3 The total desulfurization efficiency was calculated.

[0029] Step 2: Determine the in-furnace desulfurization efficiency based on the structure and operating parameters of the circulating fluidized bed boiler. The required flue gas desulfurization efficiency after the furnace is calculated based on the total desulfurization efficiency. 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 calcium-sulfur molar ratio, outlet temperature difference, and liquid-to-gas ratio are determined by empirical formulas relating these parameters to the operating parameters.

[0030] Step 3: Perform desulfurization cost analysis and optimization on the matching system of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization synergistic optimization of circulating fluidized bed boiler, including load distribution of in-furnace desulfurization and 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 and optimal operating parameters that meet SO2 emission requirements are obtained. Otherwise, return to Step 2 and Step 3 to re-optimize and determine the corresponding post-furnace flue gas desulfurization process and operating parameters.

[0031] The required desulfurization efficiency of the flue gas desulfurization process after the furnace When the sulfur content is ≤75% and the total desulfurization cost per kilogram of SO2 removed is the lowest, the following method is adopted: Figure 2The system shown is a matching system for the synergistic optimization of in-furnace enhanced desulfurization and post-furnace humidification and activation 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, post-furnace desulfurization hydrated lime conveying pipeline 18, humidification and activation reactor 19-1, humidification and activation atomizing nozzle 20-1, dust collector 21, induced draft fan 22, desulfurization ash bin 23, chimney 24, and process water tank 26. The furnace 1 is divided into three sections: a dense phase zone 2 at the bottom and a dilute phase zone 3 at the top. The input of the dense phase zone 2 is connected to the lower limestone conveying pipeline 10 and the coal feed inlet 12, while its output is connected to the dilute phase zone 3. The output of the dilute phase zone 3 is connected to the input of the cyclone separator 4. The lower output of the cyclone separator 4 is connected to the input of the riser 5, and the output of the riser 5 is connected to the input of the return feeder 6. The output of the return feeder 6 is connected to the dense phase zone 2 via the return feed leg 7. The output of the limestone powder silo 9 is connected to the dense phase zone 2 via the lower limestone conveying pipeline 10 and to the dilute phase zone 3 via the upper limestone conveying pipeline 11, thus enabling the staged addition of desulfurizing agent. The addition points for the dense phase zone 2 include the coal feed inlet 12 and the lower secondary air outlet 13; the addition point for the dilute phase zone 3 includes the upper secondary air outlet 14. The upper output end of the cyclone separator 4 is connected to the input end of the tail flue 15, and the output end of the tail flue 15 is directly connected to the input end of the humidification and activation reactor 19-1. The output end of the quicklime powder silo 16 is connected to the coal feed port 12, the lower secondary air port 13, and the upper secondary air port 14 through the in-furnace desulfurization quicklime conveying pipeline 17, and to the humidification and activation reactor 19-1 through the post-furnace desulfurization quicklime conveying pipeline 18. The output end of the process water tank 26 is connected to the interior of the humidification and activation reactor 19-1 through the humidification and activation atomizing nozzle 20-1 for atomizing and spraying process water. The output end of the humidification and activation reactor 19-1 is connected to the input end of the dust collector 21, the upper output end of the dust collector 21 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 to discharge the purified flue gas into the atmosphere. The lower output end of the dust collector 21 is connected to the input end of the desulfurization ash silo 23 for collecting desulfurization ash.

[0032] During operation, fuel is first fed from fuel silo 8 into the dense phase zone 2 of furnace 1 via coal feed inlet 12. Simultaneously, limestone is added to the dense phase zone 2 via limestone lower layer conveying pipeline 10. The fuel in the dense phase zone 2 burns, and the resulting gas-solid mixture enters the dilute phase zone 3 for further combustion and reaction. Meanwhile, limestone is added to the dilute phase zone 3 via limestone upper layer conveying pipeline 11, achieving staged desulfurization. The gas-solid mixture exits the dilute phase zone 3 into cyclone separator 4. The separated solid particles return to the dense phase zone 2 via riser 5, return feeder 6, and return feed leg 7, thus maintaining stable material circulation. When the bed temperature is below 800℃ under low load operation, a portion of the hydrated lime powder in hydrated lime powder silo 16 is conveyed via in-furnace desulfurization hydrated lime conveying pipeline 17 to a location or any combination of coal feed inlet 12, lower secondary air outlet 13, and upper secondary air outlet 14 for in-furnace desulfurization. Simultaneously, limestone powder silo 9, limestone lower layer conveying pipeline 10, and limestone upper layer conveying pipeline 11 are shut down. The flue gas separated by cyclone separator 4 is transported to humidification and activation reactor 19-1 via tail flue 15. Another portion of the hydrated lime powder in hydrated lime powder silo 16 is directly fed into humidification and activation reactor 19-1 via post-furnace desulfurization hydrated lime conveying pipeline 18. Process water tank 26 supplies water to humidification and activation atomizing nozzle 20-1, which is then atomized and sprayed into humidification and activation reactor 19-1 to achieve flue gas humidification, activation, and desulfurization, further improving desulfurization efficiency. The reacted flue gas enters dust collector 21 to remove particulate matter. The purified flue gas is then sent to chimney 24 for discharge via induced draft fan 22. The desulfurization ash collected at the bottom is collected by desulfurization ash silo 23 for subsequent treatment and comprehensive utilization.

[0033] When the desulfurization process for flue gas after the furnace requires a desulfurization efficiency of 75% or less... When the sulfur content is ≤85% and the total desulfurization cost per kilogram of SO2 removed is the lowest, the following method is adopted: Figure 3The system shown is a matching system for the synergistic optimization of in-furnace enhanced desulfurization and post-furnace spray drying 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, post-furnace desulfurization hydrated lime conveying pipeline 18, spray drying desulfurization absorption tower 19-2, rotary atomizer 20-2, dust collector 21, induced draft fan 22, desulfurization ash bin 23, chimney 24, lime slurry tank 25, and process water tank 26. 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 flue gas input end of the spray drying absorption tower 19-2, and the output ends of the hydrated lime powder silo 16 and the process water tank 26 are connected to the lime slurry tank 25. The output end of the lime slurry tank 25 is connected to the rotary atomizer 20-2, which is connected to the top of the spray drying absorption tower 19-2 to atomize the lime slurry and spray it into the spray drying absorption tower 19-2. The output end of the spray drying absorption tower 19-2 is connected to the dust collector 21 on one hand, and the upper output end of the dust collector 21 is connected to the induced draft fan 22 and the chimney 24 in sequence, while the lower output end of the dust collector 21 is connected to the desulfurization ash silo 23. The output end of the spray drying absorption tower 19-2 is also connected to the input end of the lime slurry tank 25 to return part of the desulfurization ash and realize the recycling of the desulfurizing agent.

[0034] The enhanced desulfurization section of the circulating fluidized bed boiler in this system is the same as described above. The flue gas from the upper outlet of the cyclone separator 4 enters the spray drying absorption tower 19-2 via the tail flue 15. The hydrated lime powder in the hydrated lime powder silo 16 mixes with the process water supplied from the process water tank 26 to form a uniform lime slurry. This slurry is atomized by the rotary atomizer 20-2 and sprayed into the spray drying absorption tower 19-2. Inside the tower, the atomized slurry fully contacts the flue gas, completing the post-furnace desulfurization process. The flue gas from the outlet of the spray drying absorption tower 19-2 enters the dust collector 21, where particulate matter is removed, and then it is sent to the chimney 24 for discharge by the induced draft fan 22. Part of the desulfurization ash collected by the dust collector is collected in the desulfurization ash silo 23, while the other part is returned to the lime slurry tank 25 to achieve the recycling of the desulfurizing agent and improve desulfurization efficiency.

[0035] When the desulfurization process for flue gas after the furnace requires a desulfurization efficiency of 85% or less... When the sulfur dioxide removal rate is ≤95% and the total desulfurization cost per kilogram of SO2 is lowest, the following method is adopted: Figure 4The diagram shows a matching system for the synergistic optimization of in-furnace enhanced desulfurization and post-furnace circulating fluidized bed flue gas desulfurization in a circulating fluidized bed boiler. This 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, post-furnace desulfurization hydrated 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, desulfurization ash bin 23, chimney 24, and process water tank 26. 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 duct 15 is connected to the bottom input end of the circulating fluidized bed flue gas desulfurization reactor 19-3. The output end of the hydrated lime powder silo 16 is connected to the side input end of the circulating fluidized bed flue gas desulfurization reactor 19-3 through the post-furnace desulfurization hydrated lime conveying pipeline 18. The output end of the process water tank 26 is connected to 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 to 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 to the input end of the dust collector 21. The upper flue gas output end of the dust collector 21 is connected to the induced draft fan 22 and the chimney 24 in sequence. The lower output end of the dust collector 21 is connected to the desulfurization ash silo 23 on one hand, and to the circulating fluidized bed flue gas desulfurization reactor 19-3 through the ash return pipeline on the other hand.

[0036] 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 circulating fluidized bed flue gas desulfurization reactor 19-3 via the tail flue duct 15. The hydrated lime powder from the hydrated lime powder silo 16 is sent into the circulating fluidized bed flue gas desulfurization reactor 19-3 via the desulfurization hydrated lime conveying pipeline 18 after the furnace. Water from 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, hydrated lime powder, and atomized water droplets are fully mixed and reacted within the reactor, thereby removing SO2 from the flue gas. The reacted flue gas, carrying fine desulfurization ash particles, enters the dust collector 21, and the purified flue gas is sent to the chimney 24 for discharge by the induced draft fan 22. A portion of the desulfurization ash is collected and sent to the desulfurization ash silo 23, while the other portion is returned to the circulating fluidized bed flue gas desulfurization reactor 19-3 via the return pipeline for recycling, thereby improving the recycling rate of lime and desulfurization efficiency.

[0037] The required desulfurization efficiency of the flue gas desulfurization process after the furnace When the removal rate is >95% and the total desulfurization cost per kilogram of SO2 is lowest, the following method 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 synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler, characterized in that, include: Step 1: Using the sulfur content of different coal types as the inlet constraint and the ultra-low emission concentration limit of sulfur dioxide as the outlet constraint, calculate the total desulfurization efficiency. ; 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. And determine the operating parameters such as calcium-sulfur molar ratio, outlet temperature distance, and liquid-to-gas ratio; Step 3: Perform desulfurization cost analysis and optimization on the matching system of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization synergistic optimization of circulating fluidized bed boiler, including load distribution of in-furnace desulfurization and 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 and optimal operating parameters that meet SO2 emission requirements are obtained. Otherwise, return to Step 2 and Step 3 to re-optimize and determine the corresponding post-furnace flue gas desulfurization process and operating parameters. The total desulfurization cost includes: ① the cost of in-furnace desulfurization of circulating fluidized bed boilers; ② the cost of flue gas desulfurization using post-furnace humidification and activation technology, spray drying technology, circulating fluidized bed technology, or limestone-gypsum wet flue gas desulfurization technology; and ③ other costs. The lowest total desulfurization cost is obtained by comparing the cost of in-furnace desulfurization in circulating fluidized bed boilers with the cost of flue gas desulfurization using post-furnace humidification and activation technology, spray drying technology, circulating fluidized bed technology, or limestone-gypsum wet flue gas desulfurization technology, as well as other costs. The aforementioned determination of the calcium-sulfur molar ratio operating parameters refers to: based on 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 calcium-sulfur molar ratio operating parameters are determined by empirical formulas relating these parameters to the operating parameters. Step 2 specifically includes: 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: ; 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 ; 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: , ; 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: , ; 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: .

2. The matching method for synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler according to claim 1, characterized in that, The aforementioned in-furnace desulfurization costs for circulating fluidized bed boilers include: in-furnace limestone costs. Electricity consumption for in-furnace desulfurization operation ; The flue gas desulfurization costs mentioned above, including those for post-furnace humidification and activation flue gas desulfurization technology, spray drying flue gas desulfurization technology, or circulating fluidized bed flue gas desulfurization technology, include the cost of quicklime or hydrated lime. Electricity consumption cost of desulfurization operation after furnace and water consumption costs The cost of flue gas desulfurization (FGD) using limestone-gypsum wet FGD technology includes: limestone costs. Electricity consumption costs for desulfurization operation after furnace Water consumption costs gypsum revenue and wastewater treatment costs ; Other expenses include: depreciation. Financial expenses Labor costs and repair costs ; For flue gas desulfurization processes after the furnace, humidification activation flue gas desulfurization technology, spray drying flue gas desulfurization technology, or circulating fluidized bed flue gas desulfurization technology are adopted. Circulating fluidized bed boilers remove [amount of sulfur dioxide per kilogram]. Total desulfurization cost Yuan / kg For the flue gas desulfurization process after the furnace, limestone-gypsum wet flue gas desulfurization technology is adopted, and the circulating fluidized bed boiler removes sulfur dioxide per kilogram of sulfur dioxide. Total desulfurization cost Yuan / kg ,in: 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 each year Removal amount, kg / year.

3. The matching method for synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler according to claim 1 or 2, 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 activation flue gas desulfurization in a circulating fluidized bed boiler is adopted for synergistic optimization. This matching system specifically 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... The furnace includes conveying pipelines, 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 output of the limestone powder silo is 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 outlet; the addition point in the dilute phase zone includes the upper secondary air outlet. The upper output of the cyclone separator is connected to the input of the tail flue, and the output of the tail flue is directly connected to the input of the humidification and activation reactor. The output of the hydrated lime powder silo is connected to the coal feed inlet and the lower secondary air outlet via the in-furnace desulfurization hydrated lime conveying pipeline. The process water tank is connected to the upper secondary air outlet, 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 aforementioned synergistic optimization matching system for in-furnace enhanced desulfurization and post-furnace humidification and activation of flue gas desulfurization in a circulating fluidized bed boiler first feeds fuel from the fuel silo into the dense phase zone of the furnace through the coal feed inlet. Simultaneously, a portion of limestone is added to the dense phase zone via a lower limestone conveying pipeline. The fuel combustion in the dense phase zone generates a gas-solid mixture that continues combustion and reaction in the dilute phase zone. Meanwhile, limestone is added to the dilute phase zone via an upper limestone conveying pipeline, achieving staged desulfurization. The gas-solid mixture enters a cyclone separator from the dilute phase zone outlet. The separated solid particles return to the dense phase zone via a riser, return feeder, and return leg, thus maintaining stable material circulation. When the bed temperature is below 800℃ during low-load operation, a portion of the hydrated lime powder in the hydrated lime powder silo is transported to the furnace via the in-furnace desulfurization hydrated lime conveying pipeline. In-furnace desulfurization is carried out at one or any combination of the coal feed inlet, lower secondary air inlet, and upper secondary air inlet. At the same time, the limestone powder silo, the lower limestone conveying pipeline, and the upper limestone conveying pipeline are closed. The flue gas separated by the cyclone separator is transported to the humidification and activation reactor through the tail flue. Another part of the hydrated lime powder in the hydrated lime powder silo is directly sent into the humidification and activation reactor through the desulfurization hydrated lime conveying pipeline after the furnace. The process water tank supplies water to the humidification and activation atomizing nozzle, which is sprayed into the humidification and activation reactor after atomization to achieve humidification, activation, and desulfurization of the flue gas, further improving the desulfurization efficiency. The flue gas after the reaction enters the dust collector to remove particulate matter. The purified flue gas is sent to the chimney for discharge by the induced draft fan. The desulfurization ash collected at the bottom of the dust collector is collected by the desulfurization ash silo for subsequent treatment and comprehensive utilization.

4. The matching method for synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler according to claim 1 or 2, characterized in that, When the desulfurization efficiency required for the flue gas desulfurization process after the furnace is less than 75%. When the SO2 removal rate is ≤85% and the total desulfurization cost per kilogram of SO2 is lowest, a matching system of in-furnace enhanced desulfurization and post-furnace spray drying flue gas desulfurization in a circulating fluidized bed boiler is adopted for synergistic optimization. This matching system specifically 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 furnace... The system includes a post-desulfurization lime conveying pipeline, a spray drying desulfurization absorption tower, a rotary atomizer, a dust collector, an induced draft fan, a desulfurization ash silo, a chimney, a lime slurry tank, and a process water tank. The furnace consists of a dense phase zone at the bottom and a dilute phase zone at the top. The input of the dense phase zone is connected to the lower limestone conveying pipeline and the coal feed inlet, while its output is connected to the dilute phase zone. The output of the dilute phase zone is connected to the input of a cyclone separator. The lower output of the cyclone separator is connected to the input of a riser, and the output of the riser is connected to the input of a return feeder. The output end is connected to the dense phase zone via a return leg. The output ends of the limestone powder 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 outlet; the addition point in the dilute phase zone includes the upper secondary air outlet. 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 connected to the flue gas input end of the spray drying absorption tower. The output ends of the hydrated lime powder silo and the process water tank are also connected. The system is connected to a lime slurry tank, the output of which is connected to a rotary atomizer. The rotary atomizer is connected to the top of the spray drying absorption tower to atomize the lime slurry and spray it into the tower. The output of the spray drying absorption tower is connected to a dust collector, the upper output of which is connected to an induced draft fan and a chimney, and the lower output of which is connected to a desulfurization ash silo. The output of the spray drying absorption tower is also connected to the input of the lime slurry tank to return a portion of the desulfurization ash and achieve the recycling of the desulfurizing agent. In the matching system of enhanced in-furnace desulfurization and post-furnace spray drying flue gas desulfurization in the circulating fluidized bed boiler, the flue gas from the upper outlet of the cyclone separator enters the spray drying absorption tower through the tail flue. The hydrated lime powder in the hydrated lime powder silo and the process water supplied by the process water tank are mixed to form a uniform lime slurry. The slurry is atomized by a rotary atomizer and sprayed into the spray drying absorption tower. In the tower, the atomized slurry comes into full contact with the flue gas to complete the post-furnace desulfurization process. The flue gas from the outlet of the spray drying absorption tower enters the dust collector, and after the particulate matter is removed, it is sent to the chimney by the induced draft fan for discharge. Part of the desulfurization ash collected by the dust collector is collected by the desulfurization ash silo, and the other part is returned to the lime slurry tank to realize the recycling of the desulfurizing agent and improve the desulfurization efficiency.

5. The matching method for synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler according to claim 1 or 2, characterized in that, When the desulfurization process for flue gas after the furnace requires a desulfurization efficiency of 85% or less... When the desulfurization efficiency 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 circulating fluidized bed flue gas desulfurization is adopted. This matching system specifically includes: furnace, dense phase zone, dilute phase zone, cyclone separator, riser, return feeder, return 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 system includes pipelines, a circulating fluidized bed flue gas desulfurization reactor, circulating fluidized bed flue gas desulfurization atomizing nozzles, a dust collector, an induced draft fan, a desulfurization ash silo, a chimney, and a process water tank. The furnace consists of a dense phase zone at the bottom and a dilute phase zone at the top. The input of the dense phase zone is connected to the limestone lower layer conveying pipeline and the coal feed inlet, while its output is connected to the dilute phase zone. The output of the dilute phase zone is connected to the input of a cyclone separator. The lower output of the cyclone separator is connected to the input of a riser, and the output of the riser is connected to the input of a return feeder. The output of the return feeder is connected to the dense phase zone via a return feed leg. 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 enabling staged addition of the 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 of the cyclone separator is connected to the input of the tail flue gas duct, and the output of the tail flue gas duct is connected to the bottom input of the circulating fluidized bed flue gas desulfurization reactor. The output of the slaked lime powder silo is connected to the circulating fluidized bed flue gas desulfurization reactor via a downstream desulfurization slaked lime conveying pipeline. The side input end of the flue gas desulfurization reactor is connected, the output end of the process water tank is connected to 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 to 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 to the input end of the dust collector, the upper flue gas output end of the dust collector is connected to the induced draft fan and the chimney in sequence, and the lower output end of the dust collector is connected to the desulfurization ash silo on one hand and to the circulating fluidized bed flue gas desulfurization reactor through the ash return pipeline on the other hand. In the aforementioned matching system for synergistic optimization of in-furnace enhanced desulfurization and post-furnace circulating fluidized bed flue gas desulfurization in a circulating fluidized bed boiler, 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 hydrated lime powder in the hydrated lime powder silo is sent into the circulating fluidized bed flue gas desulfurization reactor through the post-furnace desulfurization hydrated lime conveying pipeline. 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, hydrated lime powder, and atomized water droplets are fully mixed, contacted, and reacted in the reactor, thereby removing SO2 from the flue gas. The reacted flue gas carries fine desulfurization ash particles into the dust collector. The purified flue gas is sent to the chimney for discharge by the induced draft fan. Part of the desulfurization ash is collected and sent to the desulfurization ash silo, while the other part is returned to the circulating fluidized bed flue gas desulfurization reactor for recycling through the return pipeline, thereby improving the recycling rate of lime and the desulfurization efficiency.

6. The matching method for synergistic optimization of in-furnace enhanced desulfurization and post-furnace flue gas desulfurization in a circulating fluidized bed boiler according to claim 1 or 2, 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 in a circulating fluidized bed boiler and post-furnace limestone-gypsum wet flue gas desulfurization is adopted for synergistic optimization. This matching system specifically includes: furnace, dense phase zone, dilute phase zone, cyclone separator, riser, return feeder, return 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 spray suction... The furnace includes a collection tower, limestone slurry atomizing nozzles, a dust collector, an induced draft fan, a desulfurization ash silo, a chimney, a process water tank, an oxidation fan, a slurry circulation pump, a limestone powder silo behind the furnace, and a limestone slurry 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 the cyclone separator. The lower output end of the cyclone separator is connected to the input end of the riser, and the output end of the riser is connected to the input end of the return feeder. The output end of the limestone powder silo is connected to the dense phase zone via a return leg. The output ends of the limestone powder silo are 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 the 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, the output end of the tail flue is connected to the input end of the dust collector, and the upper output end 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 desulfurization ash silo; the output ends of the process water tank and the limestone powder silo after 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 enhanced desulfurization in the furnace and synergistic optimization of limestone-gypsum wet flue gas desulfurization in the circulating fluidized bed boiler, 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 limestone powder silo after the furnace are sent to the limestone slurry tank to make limestone slurry. The limestone slurry is transported to the upper part of the spray absorption tower by the slurry circulation pump and sprayed into the spray absorption tower through the limestone slurry atomizing nozzle. At the same time, the limestone slurry fully contacts the flue gas to absorb SO2 and generate calcium sulfite. At the same time, the oxidation fan introduces air into the slurry pool at the bottom of the spray absorption tower to forcibly oxidize and crystallize the calcium sulfite to generate gypsum. The flue gas after desulfurization in the spray absorption tower is heated by the flue gas heater and then enters the induced draft fan and is sent to the chimney for discharge.

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