Ammonia escape control system and control method

Abstract

The invention discloses an ammonia escape control device and method, belongs to the technical field of flue gas denitration, and solves the problems that in the prior art, escape ammonia is not completely absorbed and has backflow, and the energy reuse rate is low. The ammonia escape control device comprises a flue gas guide mechanism fixedly arranged in a flue and a treatment mechanism for treating flue gas; the smoke guiding mechanism comprises an inner gear ring, a gear is meshed with the surface of the inner gear ring and arranged at the tail end of a lead screw in a sleeving mode, supporting plates are arranged at the two ends of the lead screw, a sliding block is slidably connected to the surface of the lead screw, the supporting plates at the two ends are fixed to the surface of a positioning plate, and the positioning plate is fixed into the inner gear ring through a rotating assembly. By arranging the smoke guiding mechanism, the concentration of escaping ammonia in all positions in the flue is adjusted to be consistent, then the escaping ammonia is put into the absorption chamber, the upper concentration and the lower concentration of the absorption chamber are homogenized, it is guaranteed that the escaping ammonia is completely absorbed, meanwhile, the escaping ammonia is prevented from flowing back in the flue, ammonia water is heated, evaporated and decomposed to form ammonia gas and water vapor, and the ammonia gas is dried through the alkaline dryer; the escape ammonia is recycled, and the repeated utilization rate of energy is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas denitration, and in particular, relates to an ammonia escape control device and a control method. Background Art

[0002] Denitrification of flue gas from coal-fired power plants has been the focus of air pollutant control in recent years. The SCR method is the mainstream technology for flue gas denitrification. It has the advantages of high denitrification efficiency and mature process, and has been widely used in coal-fired power plants. In this method, ammonia enters the boiler area through the ammonia buffer tank and the delivery pipeline, and enters the SCR reactor through the distribution pilot valve after being evenly mixed with air. The SCR reactor is set in front of the air preheater. Ammonia is evenly distributed and mixed with flue gas above the SCR reactor through the spray device. After mixing, the flue gas undergoes a reduction reaction through the catalyst layer in the reactor, so that the flue gas is denitrified. However, this method has an important defect: ammonia escape. Denitrification escaped ammonia reacts with sulfur trioxide in the flue gas to form ammonium bisulfate, which will be enriched on the low-temperature heat exchange surface downstream of the SCR reactor and adhere to fly ash, resulting in blockage of the heat exchange surface and reduced heat exchange efficiency, which has a serious impact on the safe operation of the unit and the thermal efficiency of the boiler. Therefore, reducing denitrification ammonia escape is an urgent problem facing coal-fired power plants. At present, in order to solve the problem of ammonia escape in the flue gas denitrification process, it is usually adopted to inject ammonia absorbing liquid into the flue gas after denitrification to absorb the excess ammonia in the flue gas. Although this method can absorb the excess ammonia in the flue gas, the ammonia absorbing liquid is redundant. Due to the high temperature of the flue gas, in order to ensure that the excess ammonia in the flue gas is fully absorbed, the amount of ammonia absorbing liquid added is excessive. The ammonia absorbing liquid evaporates after contacting with the high-temperature flue gas, and the excess ammonia absorbing gas flows to the downstream equipment with the flue gas. Commonly, the ammonia absorbing liquid is acidic, so the ammonia absorbing gas is also acidic. The acidic gas will corrode the downstream equipment when it enters the downstream equipment. Chinese Patent 202410651026.6 solves the problem of escaping ammonia absorption, but due to the uneven density of the flue gas entering the water tank in the smoke conveying pipeline in the application, it is easy to cause uneven absorption of the water tank and uneven concentration up and down, resulting in the problem that the escaping ammonia cannot be completely absorbed and some of the escaping ammonia refluxes, which in turn affects the subsequent treatment and causes the escaping ammonia treatment to fail. Summary of the invention

[0003] The purpose of the present invention is to address the deficiencies in the prior art and to provide an ammonia escape control device and a control method with complete ammonia absorption, no reflux of ammonia, and energy reuse.

[0004] In order to achieve the above technical objectives, the technical solutions adopted by the ammonia slip control device and control method of the present invention are: An ammonia escape control device includes a smoke induction mechanism fixedly arranged in a flue and a treatment mechanism for treating the smoke; The smoke introducing mechanism comprises an inner gear ring arranged around the inner wall of the flue, the surface of the inner gear ring is meshed with a gear, the gear is sleeved on the end of the screw rod, two ends of the screw rod are provided with support plates, the surface of which is slidably connected with a slider, the support plates at both ends are fixed to the surface of the positioning plate, the positioning plate is fixed in the inner gear ring through a rotating assembly, and the surface of the positioning plate is also provided with an air supply hood, the rotating assembly comprises a fixed block, a plurality of fixed rods pass through the fixed block, the two ends of the fixed rods respectively abut against the inner wall of the inner gear ring, the inner side surface of the fixed block is rotatably connected with a rotating shaft, the front end of the rotating shaft is provided with a rotating fan blade, and the rear end passes through the fixed block and is fixedly connected to the positioning plate, the back of the rotating fan blade corresponds to the opening opened on one side of the air supply hood, the air supply hood is connected The treatment mechanism includes an absorption chamber connected to the outer tube, the absorption chamber is filled with room temperature absorption liquid, the room temperature absorption liquid is provided with an absorption promoter for promoting ammonia absorption, a liquid inlet pipe is provided on one side of the upper part of the absorption chamber, and the bottom is connected to the evaporation chamber through a connecting pipe, the evaporation chamber is arranged at a height higher than the absorption chamber, a cover plate is provided on the upper surface of the evaporation chamber, a through hole is provided on the surface of the cover plate, a hose is connected to the through hole, the hose is connected to the bottom of the drying chamber, a control valve is provided on the surface of the hose, the drying chamber is formed by an upper and lower sealing cover connected inverted, an alkaline dryer is provided in the two sealing covers, and the upper sealing cover is connected to a gas storage tank through a connecting pipe.

[0005] Preferably, the inner diameter of the inner gear ring matches the inner diameter of the flue, and is embedded in the inner wall of the flue.

[0006] Preferably, the inner straight tube and the outer tube are both arranged parallel to the positioning plate.

[0007] Preferably, a top plate is provided on the surface of the absorption chamber, and the height of the liquid in the absorption chamber is higher than the highest height of the outer tube extending into the absorption chamber.

[0008] Preferably, the unit evaporation amount of the evaporation chamber is consistent with the unit liquid delivery amount of the absorption chamber.

[0009] An ammonia slip control method comprises the following steps: S1 The device is installed in the flue. The flue gas passes through the rotating blades at high speed. The rotating blades rotate under the impetus of the flue gas. The rotating blades drive the rotating shaft to rotate. The rotating shaft drives the positioning plate and the air supply hood to rotate. At the same time, the positioning plate drives the gear to move and rotate on the inner gear ring. The gear drives the screw to rotate. The slider on the surface of the screw moves back and forth. The slider drives the air supply hood to move back and forth. The air supply hood drives the inner straight pipe to move. The inner straight pipe moves inside the outer pipe, so that the flue gas enters the outer pipe through the air supply hood, thereby replenishing the escaped ammonia missed by the edge of the fan blade when the rotating fan blade rotates, making the flue gas in the smoke pipe more evenly distributed; The S2 outer tube guides the flue gas into the absorption chamber, and the absorption promoter mixed liquid in the absorption chamber quickly absorbs ammonia to form absorption liquid. The absorption liquid continuously absorbs the excess ammonia in the flue gas input into the absorption chamber by the outer tube to form ammonia water, and the ammonia water enters the evaporation chamber from the connecting pipe; The ammonia water and water vapor in the S3 evaporation chamber rise to the drying chamber, and the ammonia passes through the dryer into the upper sealing cover. The water vapor is absorbed by the dryer, and the dryer dries the ammonia to prevent the ammonia mixed with water vapor from liquefying into ammonia water again after being cooled, thereby affecting the subsequent ammonia collection.

[0010] The adsorption promoter in step S2 is a Lewis acid ionic liquid, and its preparation comprises the following steps: 1) using chloroalkane and pyridine or imidazole and its derivatives as raw materials, heating and refluxing to synthesize chloride salt; 2) dissolving the chloride salt, the corresponding lithium or potassium salt and anhydrous cobalt chloride in acetone for anion exchange, filtering and purifying to obtain the Lewis acid ionic liquid.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a smoke entraining mechanism, adjusts the concentration of escaped ammonia at various places in the flue to be consistent, and then puts it into the absorption chamber to make the concentration above and below the absorption chamber uniform, thereby ensuring that the escaped ammonia is completely absorbed while avoiding the escaped ammonia from flowing back in the flue to generate liquid droplets, thereby affecting the subsequent collection of the escaped ammonia; after the escaped ammonia in the flue is evenly distributed, the ammonia in the room-temperature flue gas is absorbed by a room-temperature absorption liquid to form room-temperature ammonia water, and then the high-temperature flue gas is cooled by the room-temperature ammonia water, so that the ammonia water is evaporated and decomposed by heat to form ammonia and water vapor, and then the ammonia is dried by an alkaline dryer. The dried ammonia can be used for ammonia denitrification, so that the escaped ammonia can be recycled, thereby realizing energy saving of resources and improving the reuse rate of energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a structural schematic diagram of the smoke introduction mechanism in the present invention; Figure 3 It is a front view of the smoke guiding mechanism in the present invention.

[0013] In the figure: 1. inner ring gear; 2. gear; 3. screw; 4. support plate; 5. slider; 6. positioning plate; 7. air supply hood; 8. fixing block; 9. fixing rod; 10. rotating shaft; 11. rotating fan blade; 12. inner straight pipe; 13. outer straight pipe; 14. absorption chamber; 15. liquid inlet pipe; 16. connecting pipe; 17. evaporation chamber; 18. cover plate; 19. hose; 20. drying chamber; 21. control valve; 22. dryer; 23. gas storage tank; 24. top plate. DETAILED DESCRIPTION

[0014] The invention is further described below in conjunction with the accompanying drawings and specific embodiments: like Figure 1 — Figure 3 As shown, an ammonia escape control device includes a smoke induction mechanism fixedly arranged in a flue and a treatment mechanism for treating the flue gas; The smoke introduction mechanism includes an inner gear ring 1 arranged around the inner wall of the flue, the inner diameter of the inner gear ring 1 matches the inner diameter of the flue, and is embedded in the inner wall of the flue, the surface of the inner gear ring 1 is meshed with a gear 2, the gear 2 is sleeved on the end of a screw rod 3, both ends of the screw rod 3 are provided with support plates 4, the surface of which is slidably connected with a slider 5, the support plates 4 at both ends are fixed to the surface of a positioning plate 6, the positioning plate 6 is fixed in the inner gear ring 1 through a rotating component, the surface of the positioning plate 6 is also provided with an air supply cover 7, the rotating component includes a fixing block 8, A plurality of fixing rods 9 are passed through the fixing block 8, and the two ends of the fixing rods 9 are respectively in contact with the inner wall of the inner gear ring 1. The inner surface of the fixing block 8 is rotatably connected with a rotating shaft 10. The front end of the rotating shaft 10 is provided with a rotating blade 11, and the rear end passes through the fixing block 8 and is fixedly connected to the positioning plate 6. The back of the rotating blade 11 corresponds to the opening opened on one side of the air supply cover 7. The air supply cover 7 is connected with an inner straight tube 12, and the end of the inner straight tube 12 is provided with an outer tube 13, and the outer tube 13 is obliquely inserted into the processing mechanism; The treatment mechanism includes an absorption chamber 14 connected to an outer tube 13, the absorption chamber 14 is filled with room temperature absorption liquid, the room temperature absorption liquid is provided with an absorption promoter for promoting ammonia absorption, a liquid inlet pipe 15 is provided on one side of the upper part of the absorption chamber 14, and the bottom is connected to an evaporation chamber 17 via a connecting pipe 16, the evaporation chamber 17 is arranged at a height higher than the absorption chamber 14, a cover plate 18 is provided on the upper surface of the evaporation chamber 17, a through hole is provided on the surface of the cover plate 18, a hose 19 is connected to the bottom of a drying chamber 20, a control valve 21 is provided on the surface of the hose 19, the drying chamber 20 is formed by an upper and lower sealing cover connected inverted, an alkaline dryer 22 is provided in the two sealing covers, and the upper sealing cover is connected to a gas storage tank 23 via a connecting pipe. In the present invention, the air supply hood 7 rotates in the inner gear ring 1 and reciprocates in a direction parallel to the positioning plate 6, so that the smoke at various locations in the pipeline rotates through the rotation of the rotating fan blades 11, and the escaping ammonia is distributed more evenly in the smoke pipe, thereby evenly entering the absorption chamber 14, making the concentration of the upper and lower parts of the absorption tank consistent, avoiding the occurrence of liquid stratification, and at the same time avoiding the backflow of escaping ammonia to affect the denitrification effect. At the same time, the outer tube 13 is inclined, and its air outlet end is located at the upper part of the absorption chamber 14. After the upper liquid absorbs ammonia, the concentration in the upper part is higher than that in the lower part, forming a liquid seal. Since the concentration of ammonia in the upper and lower parts of the outer tube 13 is balanced, the ammonia is moved to the lower part of the absorption chamber 14 to achieve effective absorption of ammonia.

[0015] In the present invention, the inner straight tube 12 and the outer tube 13 are both arranged parallel to the positioning plate 6. By arranging the inner straight tube 12 and the outer tube 13 parallel to the positioning plate 6, it is ensured that the movement of the positioning plate 6 drives the inner straight tube 12 to move in the same direction, guiding the flue gas into the absorption chamber 14.

[0016] In the present invention, a top plate 24 is provided on the surface of the absorption chamber 14, the height of the liquid in the absorption chamber 14 is higher than the highest height of the outer tube 13 extending into the absorption chamber 14, and the unit evaporation amount of the evaporation chamber 17 is consistent with the unit liquid delivery amount of the absorption chamber 14. The unit evaporation amount of the evaporation chamber 17 is kept consistent with the liquid delivery amount of the absorption chamber 14 to ensure that the evaporation chamber 17 can completely treat the corresponding ammonia water.

[0017] A method for controlling ammonia slip in the present invention comprises the following steps: S1 The device is installed in the flue. The flue gas passes through the rotating blades at high speed. The rotating blades rotate under the impetus of the flue gas. The rotating blades drive the rotating shaft to rotate. The rotating shaft drives the positioning plate and the air supply hood to rotate. At the same time, the positioning plate drives the gear to move and rotate on the inner gear ring. The gear drives the screw to rotate. The slider on the surface of the screw moves back and forth. The slider drives the air supply hood to move back and forth. The air supply hood drives the inner straight pipe to move. The inner straight pipe moves inside the outer pipe, so that the flue gas enters the outer pipe through the air supply hood, thereby replenishing the escaped ammonia missed by the edge of the fan blade when the rotating fan blade rotates, making the flue gas in the smoke pipe more evenly distributed; The S2 outer tube guides the flue gas into the absorption chamber, and the absorption promoter mixed liquid in the absorption chamber quickly absorbs ammonia to form absorption liquid. The absorption liquid continuously absorbs the excess ammonia in the flue gas input into the absorption chamber by the outer tube to form ammonia water, and the ammonia water enters the evaporation chamber from the connecting pipe; The ammonia water and water vapor in the S3 evaporation chamber rise to the drying chamber, and the ammonia passes through the dryer and enters the upper sealing cover. The water vapor is absorbed by the dryer, and the dryer dries the ammonia to prevent the ammonia mixed with water vapor from being liquefied into ammonia water again after being cooled, which in turn affects the subsequent ammonia collection. The dryer is an alkaline dryer filled with calcium carbonate. The alkaline dryer is heated by high-temperature flue gas, so that the calcium carbonate in the alkaline dryer is thermally decomposed and the alkaline desiccant quicklime is regenerated for reuse, which is energy-saving and environmentally friendly. The thermal decomposition of calcium carbonate and the evaporation of ammonia water require a lot of heat. The high-temperature flue gas has sufficient thermal energy. The heat of the high-temperature flue gas is effectively utilized to ensure the thermal decomposition of calcium carbonate and the evaporation of ammonia water, while reducing the temperature of the flue gas and entering the absorption liquid. While effectively utilizing energy, the absorption liquid is prevented from evaporating and the ammonia gas escapes.

[0018] The adsorption promoter in step S2 is a Lewis acid ionic liquid, and its preparation comprises the following steps: 1) using chloroalkane and pyridine or imidazole and its derivatives as raw materials, heating and refluxing to synthesize chloride salt; 2) dissolving the chloride salt, the corresponding lithium or potassium salt and anhydrous cobalt chloride in acetone for anion exchange, filtering and purifying to obtain the Lewis acid ionic liquid.

[0019] The adsorption promoter in step S2 improves the absorption performance of ammonia through the chemical complexation between divalent metal cobalt ions and ammonia molecules, and cooperates with the absorption performance of liquid at room temperature to further improve the absorption rate of ammonia in the absorption chamber. At the same time, the chemical action of the adsorption promoter is weaker than the complexation between other transition metals and ammonia. Therefore, the ammonia is desorbed by heating during evaporation, and then the ammonia is dried in a dryer to facilitate the subsequent collection of escaping ammonia.

[0020] The present invention evenly distributes the escaped ammonia in the flue, and then uses a room-temperature absorption liquid to absorb the ammonia in the room-temperature flue gas to form room-temperature ammonia water, and then uses the room-temperature ammonia water to cool the high-temperature flue gas, so that the ammonia water is evaporated and decomposed by heat to form ammonia and water vapor, and then uses an alkaline dryer to dry the ammonia. The dried ammonia can be used for ammonia denitrification, so that the escaped ammonia can be recycled and utilized, and energy conservation of resources is achieved. Since the room-temperature absorption liquid has a limited ability to absorb ammonia, if a large amount of escaped ammonia enters, the absorption efficiency of the liquid in the tank is low. Therefore, an absorption promoter is added to the room-temperature absorption liquid to improve the absorption efficiency of the ammonia in the absorption liquid while avoiding changes in the liquid form.

[0021] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. All equivalent changes and modifications in the shape, structure, characteristics and spirit of the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. An ammonia slip control device, characterized in that: It includes a smoke inlet mechanism fixed in the flue and a smoke treatment mechanism for treating the smoke; The smoke introducing mechanism comprises an inner gear ring arranged around the inner wall of the flue, the surface of the inner gear ring is meshed with a gear, the gear is sleeved on the end of the screw rod, two ends of the screw rod are provided with support plates, the surface of which is slidably connected with a slider, the support plates at both ends are fixed to the surface of the positioning plate, the positioning plate is fixed in the inner gear ring through a rotating assembly, and the surface of the positioning plate is also provided with an air supply hood, the rotating assembly comprises a fixed block, a plurality of fixed rods pass through the fixed block, the two ends of the fixed rods respectively abut against the inner wall of the inner gear ring, the inner side surface of the fixed block is rotatably connected with a rotating shaft, the front end of the rotating shaft is provided with a rotating fan blade, and the rear end passes through the fixed block and is fixedly connected to the positioning plate, the back of the rotating fan blade corresponds to the opening opened on one side of the air supply hood, the air supply hood is connected The treatment mechanism includes an absorption chamber connected to the outer tube, the absorption chamber is filled with room temperature absorption liquid, the room temperature absorption liquid is provided with an absorption promoter for promoting ammonia absorption, a liquid inlet pipe is provided on one side of the upper part of the absorption chamber, and the bottom is connected to the evaporation chamber through a connecting pipe, the evaporation chamber is arranged at a height higher than the absorption chamber, a cover plate is provided on the upper surface of the evaporation chamber, a through hole is provided on the surface of the cover plate, a hose is connected to the through hole, the hose is connected to the bottom of the drying chamber, a control valve is provided on the surface of the hose, the drying chamber is formed by an upper and lower sealing cover connected inverted, an alkaline dryer is provided in the two sealing covers, and the upper sealing cover is connected to a gas storage tank through a connecting pipe.

2. The ammonia slip control device according to claim 1, characterized in that: The inner diameter of the inner gear ring matches the inner diameter of the flue and is embedded in the inner wall of the flue.

3. The ammonia slip control device according to claim 1, characterized in that: The inner straight tube and the outer tube are both arranged parallel to the positioning plate.

4. The ammonia slip control device according to claim 1, characterized in that: The surface of the absorption chamber is provided with a top plate, and the height of the liquid in the absorption chamber is higher than the highest height of the outer tube extending into the absorption chamber.

5. The ammonia slip control device according to claim 1, characterized in that: The unit evaporation amount of the evaporation chamber is consistent with the unit liquid delivery amount of the absorption chamber.

6. A method for controlling ammonia slip, characterized in that: The following steps are involved: S1 The device is installed in the flue. The flue gas passes through the rotating blades at high speed. The rotating blades rotate under the impetus of the flue gas. The rotating blades drive the rotating shaft to rotate. The rotating shaft drives the positioning plate and the air supply hood to rotate. At the same time, the positioning plate drives the gear to move and rotate on the inner gear ring. The gear drives the screw to rotate. The slider on the surface of the screw moves back and forth. The slider drives the air supply hood to move back and forth. The air supply hood drives the inner straight pipe to move. The inner straight pipe moves inside the outer pipe, so that the flue gas enters the outer pipe through the air supply hood, thereby replenishing the escaped ammonia missed by the edge of the fan blade when the rotating fan blade rotates, making the flue gas in the smoke pipe more evenly distributed; The S2 outer tube guides the flue gas into the absorption chamber, and the absorption promoter mixed liquid in the absorption chamber quickly absorbs ammonia to form absorption liquid. The absorption liquid continuously absorbs the excess ammonia in the flue gas input into the absorption chamber by the outer tube to form ammonia water, and the ammonia water enters the evaporation chamber from the connecting pipe; The ammonia water and water vapor in the S3 evaporation chamber rise to the drying chamber, and the ammonia passes through the dryer into the upper sealing cover. The water vapor is absorbed by the dryer, and the dryer dries the ammonia to prevent the ammonia mixed with water vapor from liquefying into ammonia water again after being cooled, thereby affecting the subsequent ammonia collection.

7. The ammonia slip control method according to claim 6, characterized in that: The adsorption promoter in step S2 is a Lewis acid ionic liquid, and its preparation comprises the following steps: 1) Using chloroalkane and pyridine or imidazole and its derivatives as raw materials, heating reflux reaction to synthesize chloride salt; 2) then dissolving the chloride salt, the corresponding lithium or potassium salt and anhydrous cobalt chloride in acetone to perform anion exchange, filtering and purifying to obtain Lewis acid ionic liquid.

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