A desulfurization system for coal-fired boilers

Abstract

This utility model discloses a desulfurization system for a coal-fired boiler, including a desulfurization tower connected to the flue gas duct of the coal-fired boiler via a flue gas inlet pipe. A wet electrostatic precipitator, an induced draft fan, and a chimney are sequentially installed on the flue gas outlet pipe behind the desulfurization tower. The desulfurization tower has multiple layers of spray pipes inside, and a slurry pool is located at the bottom of the tower. The slurry pool is connected to the spray pipes via a circulation pipe, which is equipped with a circulation pump. An oxidation pipe is connected to the top of the desulfurization tower, and an oxidation fan is installed on the oxidation pipe. A desulfurizing agent preparation mechanism is connected to the slurry pool at the bottom of the desulfurization tower. A slurry treatment mechanism is also connected to the bottom of the desulfurization tower via a pipe. This utility model optimizes process design, enhances material circulation, and implements precise parameter control. By utilizing spray layer atomization and forced oxidation by the oxidation fan, it ensures desulfurization effectiveness, improves the overall operating efficiency of the system, and enhances resource utilization through gypsum dewatering and filtrate recycling.

Description

Technical Field

[0001] This utility model relates to the field of coal-fired boiler technology, and more specifically to a desulfurization system for coal-fired boilers. Background Technology

[0002] With increasingly stringent environmental protection requirements, boiler flue gas desulfurization has become a crucial step in controlling sulfur dioxide emissions in industrial production. Traditional limestone-gypsum desulfurization systems suffer from problems such as loose process integration, low material recycling efficiency, and insufficient precision in desulfurization parameter control, leading to unstable desulfurization effects, resource waste, and high operating costs. Therefore, there is an urgent need for a desulfurization system that optimizes the process, improves efficiency, and enhances automation. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a desulfurization system for coal-fired boilers, which achieves stable and efficient desulfurization, maximizes resource recovery and reduces operating costs by optimizing process design, strengthening material circulation and precise parameter control.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows.

[0005] A desulfurization system for a coal-fired boiler includes a desulfurization tower connected to the flue gas duct of the coal-fired boiler via a flue gas inlet pipe for desulfurizing the discharged flue gas. A wet electrostatic precipitator, an induced draft fan, and a chimney are sequentially installed on the flue gas outlet pipe behind the desulfurization tower. The desulfurization tower has multiple layers of spray pipes inside, and a slurry pool is located at the bottom of the tower. The slurry pool is connected to the spray pipes via a circulation pipe, which is equipped with a circulation pump. An oxidation pipe for introducing oxygen into the desulfurization tower is connected to the top of the tower, and an oxidation fan is installed on the oxidation pipe. A desulfurizing agent preparation mechanism for adding desulfurization slurry to the slurry pool is connected to the bottom of the desulfurization tower via a pipe. A slurry treatment mechanism for treating sediment in the slurry pool is also connected to the bottom of the desulfurization tower via a pipe.

[0006] To further optimize the technical solution, the desulfurizing agent preparation mechanism includes a slurry preparation tank connected to a slurry tank via a pipeline. The feed end of the slurry preparation tank is connected to a limestone powder tank for storing limestone powder and a process water tank for storing process water. The slurry preparation tank is equipped with a stirring blade for stirring the added limestone powder and process water. The slurry preparation tank is equipped with a stirring motor for driving the stirring blade to rotate. The pipeline connecting the slurry preparation tank and the slurry tank is equipped with a slurry supply pump for sending the prepared slurry into the slurry tank.

[0007] To further optimize the technical solution, a rotary feeder for adding limestone powder into the slurry preparation tank is installed between the limestone powder tank and the slurry preparation tank.

[0008] The technical solution is further optimized. The slurry treatment mechanism includes a gypsum hydrocyclone connected to the discharge end of the slurry tank via a pipeline for separating gypsum from the discharged slurry. The discharge end of the gypsum hydrocyclone is equipped with a belt dewatering machine for dehydrating the separated gypsum. A gypsum storage tank for storing gypsum is connected to the belt dewatering machine. The discharge ends of the gypsum hydrocyclone and the belt dewatering machine are respectively connected to the slurry preparation tank via pipelines.

[0009] To further optimize the technical solution, the pipes connecting the gypsum hydrocyclone and the belt dewatering machine to the slurry preparation tank are respectively equipped with filtrate pumps for pumping the filtered slurry into the slurry preparation tank.

[0010] To further optimize the technical solution, the pipe connecting the gypsum hydrocyclone to the slurry tank is equipped with a gypsum discharge valve and a gypsum discharge pump for controlling the discharge of slurry.

[0011] The technological advancements achieved by this utility model are as follows, due to the adoption of the above technical solutions.

[0012] This utility model provides a desulfurization system for coal-fired boilers. By optimizing process design, strengthening material circulation and precise parameter control, it utilizes spray layer atomization and oxidation fan forced oxidation to ensure desulfurization effect and improve the overall operating efficiency of the system. The gypsum dewatering and recycling and filtrate recycling maximize resource recovery, reduce material and water consumption, and improve resource utilization. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of this utility model.

[0014] The components include: 1. Desulfurization tower, 2. Flue gas inlet pipe, 3. Flue gas outlet pipe, 4. Wet electrostatic precipitator, 5. Exhaust fan, 6. Chimney, 7. Slurry preparation tank, 8. Limestone powder tank, 9. Rotary feeder, 10. Process water tank, 11. Slurry pump, 12. Circulation pipe, 13. Circulation pump, 14. Gypsum hydrocyclone, 15. Gypsum discharge pump, 16. Gypsum discharge valve, 17. Belt dewatering machine, 18. Gypsum silo, 19. Filtration water pump, 20. Oxidation pipe, and 21. Oxidation fan. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0016] A desulfurization system for a coal-fired boiler, combined with Figure 1As shown, it includes a desulfurization tower 1, which is connected to the flue of a coal-fired boiler via a flue gas inlet pipe 2 to desulfurize the flue gas discharged from the boiler. A wet electrostatic precipitator 4, an induced draft fan 5, and a chimney 6 are sequentially installed on the flue gas outlet pipe 3 behind the desulfurization tower 1. The wet electrostatic precipitator is used to remove dust from the desulfurized flue gas, the induced draft fan provides negative pressure to the flue gas discharged from the coal-fired boiler, and the chimney is used to discharge the purified flue gas.

[0017] The desulfurization tower 1 is equipped with multiple layers of spray pipes to spray and desulfurize the incoming flue gas. The bottom of the desulfurization tower 1 is equipped with a slurry tank. The slurry tank is connected to the spray pipes through a circulation pipe 12. A circulation pump 13 is installed on the circulation pipe 12 to send the desulfurization slurry in the slurry tank into the spray pipes to desulfurize the flue gas, thereby realizing the recycling of the desulfurization slurry.

[0018] An oxidation pipe 20 is connected to the desulfurization tower 1, and an oxidation fan 21 is installed on the oxidation pipe to introduce oxygen into the desulfurization tower. The oxygen reacts with the desulfurization slurry to promote the sulfidation reaction. During the desulfurization process, the limestone slurry in the desulfurization tower reacts with sulfur dioxide in the flue gas to first form sulfite. After oxygen is introduced, the unstable sulfite is oxidized into stable sulfate, creating conditions for the final formation of gypsum, improving desulfurization efficiency and product stability, and making desulfurization more thorough.

[0019] A desulfurizing agent preparation mechanism is connected to the slurry pool at the bottom of the desulfurization tower 1. This mechanism is used to prepare desulfurizing agent slurry and add it to the slurry pool. The desulfurizing agent preparation mechanism includes a slurry preparation tank 7 connected to the slurry pool via a pipeline. The feed end of the slurry preparation tank 7 is connected to a limestone powder tank 8 and a process water tank 10. The limestone powder tank 8 is used to store limestone powder. A rotary feeder 9 is installed between the limestone powder tank 8 and the slurry preparation tank 7 to add limestone powder to the slurry preparation tank. The process water tank 10 is used to hold process water. The slurry preparation tank is equipped with a stirring blade and a stirring motor to drive the stirring blade to rotate and stir the limestone powder and process water in the slurry preparation tank to form the desulfurizing agent slurry. A slurry supply pump 11 is installed on the pipeline connecting the slurry preparation tank 7 and the slurry pool to deliver the prepared slurry into the slurry pool.

[0020] The bottom of the desulfurization tower 1 is connected to a slurry treatment mechanism via a pipeline, which is used to treat the gypsum slurry that has settled in the slurry. The slurry treatment mechanism includes a gypsum hydrocyclone 14 connected to the discharge end of the slurry tank via a pipeline, which is used to separate the gypsum in the discharged slurry. A belt dewatering machine 17 is installed at the discharge end of the gypsum hydrocyclone 14, which is used to dewater the separated gypsum. A gypsum silo 18 is connected to the belt dewatering machine, which is used to store gypsum.

[0021] The outlet ends of the gypsum hydrocyclone 14 and the belt dewatering machine 17 are respectively connected to the slurry preparation tank 7 through pipes. The pipes connecting the gypsum hydrocyclone 14 and the belt dewatering machine 17 to the slurry preparation tank 7 are respectively equipped with filtrate pumps 19, which are used to pump the slurry filtered by the gypsum hydrocyclone 14 and the belt dewatering machine 17 into the slurry preparation tank.

[0022] The gypsum hydrocyclone 14 is connected to the slurry tank by a gypsum discharge valve 16 and a gypsum discharge pump 15, which are used to control the discharge of slurry and transport the slurry into the gypsum hydrocyclone for processing.

[0023] In this invention, flue gas from a coal-fired boiler is transported to a desulfurization tower via pipeline. Limestone powder and process water from outside the desulfurization tower enter a slurry preparation tank and are stirred to prepare a desulfurization slurry. The desulfurization slurry is then pumped to a slurry pool at the bottom of the desulfurization tower. The slurry is then sprayed downwards through a circulation pump and pipeline. During spraying, the flue gas rises from the bottom of the desulfurization tower, contacting the downward-spraying desulfurization slurry in a counter-current manner. SO2 reacts with CaCO3 in the slurry to form calcium sulfite (CaSO3), achieving preliminary desulfurization. Oxygen is introduced into the bottom of the desulfurization tower through an oxidation fan box to oxidize CaSO3 into calcium sulfate (CaSO4), laying the foundation for subsequent gypsum molding. The flue gas from the desulfurization tower then enters a wet electrostatic precipitator, where an electric field further captures fine droplets, dust, and other pollutants, deeply purifying the flue gas and ultimately releasing clean flue gas that meets environmental protection requirements. The cleaned flue gas is then discharged as part of the flue gas emission process.

[0024] At the bottom of the desulfurization tower, the slurry rich in CaSO4 is pumped to a gypsum hydrocyclone by a gypsum discharge pump. The gypsum hydrocyclone uses centrifugal force to achieve "concentration and separation" of the slurry: the underflow (concentrated slurry with high solids content) goes to the belt dewatering machine; the overflow (filtrate with low solids content) is returned to the slurry preparation unit, realizing water resource reuse. The concentrated slurry enters the belt dewatering machine, and through processes such as vacuum suction and belt extrusion, it is dehydrated to form gypsum CaSO4·2H2O, which is collected as a by-product in the gypsum storage unit; the filtrate produced by dewatering is also returned to the slurry preparation unit, achieving "water system circulation".

Claims

1. A coal-fired boiler desulfurization system, characterized by: Including through The flue gas inlet pipe (2) is connected to the flue of the coal-fired boiler to a desulfurization tower (1) for desulfurizing the discharged flue gas. A wet electrostatic precipitator (4), an induced draft fan (5) and a chimney (6) are installed in sequence on the flue gas outlet pipe (3) behind the desulfurization tower (1). The desulfurization tower (1) is equipped with multiple spray pipes inside. A slurry pool is installed at the bottom of the desulfurization tower (1). The slurry pool is connected to the spray pipes through a circulation pipe (12). A circulation pump (13) is installed on the circulation pipe (12). An oxidation pipe (20) for introducing oxygen into the desulfurization tower (1) is connected to the desulfurization tower (1). An oxidation fan (21) is installed on the oxidation pipe. A desulfurizing agent preparation mechanism for adding desulfurization slurry to the slurry pool is connected to the slurry pool at the bottom of the desulfurization tower (1). A slurry treatment mechanism for sedimentation in the slurry pool is connected to the bottom of the desulfurization tower (1) through a pipe.

2. The desulfurization system for a coal-fired boiler according to claim 1, characterized in that: The desulfurizing agent preparation mechanism includes a slurry preparation tank (7) connected to a slurry tank via a pipeline. The feed end of the slurry preparation tank (7) is connected to a limestone powder tank (8) for storing limestone powder and a process water tank (10) for storing process water. The slurry preparation tank is equipped with a stirring blade for stirring the added limestone powder and process water. The slurry preparation tank is equipped with a stirring motor for driving the stirring blade to rotate. The pipeline connecting the slurry preparation tank (7) and the slurry tank is equipped with a slurry pump (11) for sending the prepared slurry into the slurry tank.

3. A coal-fired boiler desulphurisation system according to claim 2, characterised in that: A rotary feeder (9) for adding limestone powder into the slurry preparation tank is provided between the limestone powder tank (8) and the slurry preparation tank (7).

4. A coal-fired boiler desulphurisation system according to claim 2, wherein: The slurry treatment mechanism includes a gypsum hydrocyclone (14) connected to the discharge end of the slurry tank via a pipe for separating gypsum from the discharged slurry. The discharge end of the gypsum hydrocyclone is equipped with a belt dewatering machine (17) for dehydrating the separated gypsum. A gypsum storage tank (18) for storing gypsum is connected to the belt dewatering machine. The liquid outlets of the gypsum hydrocyclone (14) and the belt dewatering machine (17) are respectively connected to the slurry preparation tank (7) via pipes.

5. A coal-fired boiler desulphurisation system according to claim 4, wherein: The pipes connecting the gypsum hydrocyclone (14) and the belt dewatering machine (17) to the slurry preparation tank (7) are respectively equipped with filtrate pumps (19) for pumping the filtered slurry into the slurry preparation tank.

6. A coal-fired boiler desulphurisation system according to claim 4, wherein: The gypsum hydrocyclone (14) is connected to the slurry tank by a gypsum discharge valve (16) and a gypsum discharge pump (15) for controlling the discharge of slurry.

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