Ammonia water storage tank tail gas treatment device and method for SCR denitration

Abstract

The application provides an ammonia water storage tank tail gas treatment device and method for SCR denitration, which comprises an ammonia water storage tank, a buffer tank, an SCR denitration reactor, a mixing pipe, a flue gas pipeline, a spraying assembly, an ammonia injection grid, a booster fan and a dilution air supply unit; an exhaust port at the top of the ammonia water storage tank is connected to the buffer tank through a tail gas delivery main pipe, the buffer tank is connected to the spraying assembly in the flue gas pipeline through a first delivery branch, the storage tank is additionally provided with a bypass delivery branch connected to the dilution air supply unit and connected to the ammonia injection grid; a condensate collection port is arranged at the bottom of the buffer tank and connected to the ammonia water storage tank through a condensing delivery pipe and a ammonia delivery pump and a reflux; the ammonia water storage tank is provided with a pressure transmitter and a breather valve, the pressure transmitter is connected to two-way pipeline on-off and flow control, the double-path tail gas reuse, buffer pressure stabilization, gas-liquid separation and condensing reflux closed loop structure realize the graded utilization of ammonia-containing tail gas, stable pressure and flow, raw material saving and tail gas emission reduction.

Description

Technical Field

[0001] This invention relates to the field of denitrification equipment technology, specifically to a device and method for treating the tail gas of an ammonia storage tank used in SCR denitrification. Background Technology

[0002] SCR denitrification is a mainstream flue gas purification process that uses ammonia to reduce nitrogen oxides in flue gas to produce nitrogen and water under the action of a catalyst, thereby removing nitrogen oxides from the flue gas. In actual engineering, ammonia water with a mass concentration of 10% to 30% is usually used as the ammonia source. The ammonia water is first vaporized into ammonia in an ammonia evaporator, and then mixed with dilution air heated by steam to form a mixed gas with an ammonia concentration of less than 5%. The mixed gas is then sent into the SCR denitrification reactor through an ammonia injection grid to participate in the reaction.

[0003] Ammonia water is highly volatile. During the process of adding ammonia water to the ammonia water storage tank, the pressure inside the tank rises rapidly and a large amount of ammonia-containing tail gas is released. Ammonia gas is highly irritating and toxic. Unorganized emissions can easily cause air pollution and endanger the occupational health and safety of on-site personnel. The current conventional treatment method is to add an independent absorption device or build a new absorption tower, using water or acid to absorb and purify the ammonia-containing tail gas. However, due to limitations in ammonia water concentration, tank temperature, feed flow rate, absorbent capacity, and absorption rate, a large amount of ammonia gas cannot be completely absorbed, and some ammonia gas is still directly discharged, posing significant environmental and safety hazards.

[0004] Meanwhile, ammonia itself can be used as a denitrification agent in SCR denitrification, but the existing absorption treatment method dissolves and discards ammonia, resulting in a waste of ammonia resources.

[0005] The purpose of this invention is to provide a device and method for treating the tail gas of an ammonia storage tank used in SCR denitrification, so as to solve the problems mentioned in the background art. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides an ammonia storage tank tail gas treatment device for SCR denitrification, comprising an ammonia storage tank, a buffer tank, an SCR denitrification reactor, a mixing pipe disposed at the inlet end of the SCR denitrification reactor, a flue gas duct connected to the inlet end of the mixing pipe, an injection assembly disposed in the flue gas duct, an ammonia injection grid connected to the mixing pipe, a booster fan connected to the outlet end of the SCR denitrification reactor, and a dilution air supply unit. The ammonia storage tank is equipped with a tail gas conveying main pipe and an ammonia water pipe. The exhaust port at the top of the ammonia storage tank is connected to the air inlet of the buffer tank through the tail gas conveying main pipe. The air outlet of the buffer tank is connected to the injection component in the flue gas pipeline through the first conveying branch. The ammonia water pipe is connected to external ammonia water through an ammonia water pump. The top of the ammonia storage tank is also equipped with a bypass conveying branch. The output end of the bypass conveying branch is connected to the dilution air supply unit, and the outlet of the dilution air supply unit is connected to the ammonia injection grid in the mixing pipe. The bottom of the buffer tank is equipped with a condensate collection port, which is connected to the inside of the ammonia storage tank through a condensate delivery pipe. A vent valve is installed on the condensate collection port. The buffer tank and the ammonia storage tank have two relative layout positions: the first layout position is that the liquid level of the buffer tank is higher than that of the ammonia storage tank, and the condensation conveying pipe relies on the liquid level difference to achieve gravity flow of condensed ammonia back to the ammonia storage tank; the second layout position is that the liquid level of the buffer tank is lower than that of the ammonia storage tank, and the condensation conveying pipe is equipped with an ammonia pump and a liquid level gauge, relying on the power of the pump to transport condensed ammonia to the ammonia storage tank. The ammonia storage tank is equipped with a pressure transmitter and a breather valve. The pressure transmitter is interlocked with the on / off and flow regulation structure of the first conveying branch and the bypass conveying branch. By setting up a dual-path tail gas reuse structure, a buffer pressure stabilizing gas-liquid separation and condensation reflux closed-loop structure, the ammonia-containing tail gas from the ammonia storage tank is recycled and reused in stages, stabilizing the pressure fluctuations of the tank tail gas, improving the stability of SCR denitrification and ammonia supply, and reducing ammonia escape; at the same time, the condensed ammonia water is recovered, saving raw material consumption and reducing the fugitive emissions of ammonia-containing tail gas.

[0007] As a further improvement of the present invention, flow regulating valve one and flow regulating valve two are respectively provided on the exhaust gas conveying main pipe and the bypass conveying branch for adjusting the pipeline opening and closing and the conveying flow rate. The two pipelines are equipped with independent flow regulating valves, which can adjust the main pipeline exhaust gas reuse flow and the bypass pressure relief flow according to the tank pressure conditions. The operating conditions can be switched flexibly and the adjustment accuracy is high, ensuring stable system operation and safe pressure relief.

[0008] As a further improvement of the present invention, the injection assembly includes an air supply pipe and several nozzles. The nozzles are evenly arranged inside the flue gas pipe. A through hole is provided on the outer wall of the flue gas pipe corresponding to the position of each nozzle. An air supply pipe is provided on the outside of the flue gas pipe corresponding to the position of the through hole. The air supply pipe is connected to the outlet end of the first delivery branch. By using an external gas delivery pipe in conjunction with a multi-point uniform nozzle arrangement in the pipeline, ammonia-containing exhaust gas can be uniformly injected into the flue gas cross section, effectively improving the uniformity of ammonia-fume mixing and avoiding the problem of poor denitrification efficiency caused by uneven local ammonia concentration.

[0009] As a further improvement of the present invention, the spray direction of several nozzles is arranged at an angle opposite to the flow direction of flue gas inside the flue gas duct.

[0010] As a further improvement of the present invention, the angle between the nozzle and the flue gas duct is 15°-75°.

[0011] By spraying at a reverse angle through the nozzle, the turbulence of flue gas is used to enhance the mixing of ammonia fumes, shorten the mixing distance, improve the mixing efficiency of exhaust gas and flue gas, and increase the resource utilization rate of ammonia water exhaust gas.

[0012] As a further improvement of the present invention, the buffer tank is equipped with a safety valve; when the buffer tank is in the second deployment position, the level gauge, the vent valve, and the ammonia transfer pump are interlocked for start and stop. The buffer tank is equipped with a safety valve and a level gauge. Under low-level conditions, the level gauge is linked to the vent valve and the ammonia pump for interlocking start and stop. The level gauge and pressure relief components are interlocked to automatically monitor and discharge accumulated liquid, which can not only ensure the pressure stabilization and gas-liquid separation effect of the buffer tank, but also prevent the tank from overpressure and liquid overflow, thereby improving the safety of equipment operation and the level of automated control.

[0013] As a further improvement of the present invention, the dilution air supply unit includes a dilution air inlet pipe, a dilution air outlet pipe, and a dilution fan. The dilution air inlet pipe and the dilution air outlet pipe are respectively connected to the inlet end and the outlet end of the dilution fan. A flow regulating valve three is provided on the dilution air inlet pipe. The flow regulating valve three is interlocked with the pressure transmitter at the top of the ammonia storage tank. By interlocking the dilution airflow with the storage tank pressure, the dilution airflow can be dynamically matched according to the exhaust gas intake, stabilizing the ammonia-air mixture concentration, ensuring uniform gas distribution at the ammonia injection grid, and adapting to the denitrification operation requirements under varying working conditions.

[0014] As a further improvement of the present invention, it also includes an ammonia evaporator connected to an ammonia storage tank. The ammonia storage tank and the ammonia evaporator are connected through an ammonia conveying main pipe. An ammonia conveying pump II is provided on the ammonia conveying main pipe. The gas outlet of the ammonia evaporator is connected to a dilution gas outlet pipe. By setting up an ammonia evaporator, a main ammonia supply pipe connecting the ammonia storage tank and the evaporator, and an ammonia pump, the ammonia in the ammonia storage tank can be transported to the evaporator to participate in the reaction, thus expanding the ammonia source supply path for tail gas treatment.

[0015] As a further improvement of the present invention, the condensation conveying pipe is provided with a first diversion section and a second diversion section. The first diversion section is connected to the ammonia storage tank, and the second diversion section is connected to the ammonia conveying main pipe of the ammonia evaporator. The ammonia conveying main pipe is provided with an ammonia recovery branch pipe 1 connected to the ammonia storage tank. An ammonia recovery branch pipe 2 is connected to the first diversion section. The other end of the ammonia recovery branch pipe 2 is connected to the ammonia recovery branch pipe 1. An ammonia pump 1 is installed on the ammonia recovery branch pipe 2. An ammonia branch pipe is also connected between the ammonia conveying main pipe and the ammonia recovery branch pipe 2. By setting up a first diversion section and a second diversion section in the condensate delivery pipe, and matching it with ammonia water recovery branch pipe one, ammonia water recovery branch pipe two, ammonia delivery branch pipe and ammonia delivery pump one, a one-in-one-backup delivery path can be formed with ammonia delivery pump two, improving the reliability of condensate ammonia water delivery operation under low-level working conditions.

[0016] A method for treating the tail gas from an ammonia storage tank used in SCR denitrification includes the following steps: Step 1: The pressure inside the ammonia storage tank is monitored in real time by a pressure transmitter. The ammonia-containing tail gas generated by the ammonia storage tank is sent to the buffer tank through the tail gas delivery main pipeline to complete the pressure buffering and gas-liquid separation. Step 2: When the ammonia storage tank is in the normal pressure range, close the bypass conveying branch and only open the first conveying branch. The pressure-stabilized ammonia-containing tail gas is conveyed to the injection assembly through the first conveying branch and sprayed into the flue gas pipeline in reverse by the injection assembly to complete the initial uniform mixing with the flue gas to be denitrified. Step 3: When the internal pressure of the ammonia storage tank exceeds the standard, the bypass delivery branch is opened by interlock and the air intake flow of the dilution air supply unit is adjusted to introduce the excess ammonia-containing tail gas from the ammonia storage tank into the dilution air supply unit. At the same time, the denitrified ammonia gas produced by the ammonia evaporator is incorporated into the dilution air supply unit and mixed with the ammonia-containing tail gas from the bypass to dilute it. Step 4: The diluted and mixed ammonia-air mixture is evenly distributed into the flue gas through the ammonia injection grid in the mixing pipe. The flue gas passes through the upstream injection component and the downstream ammonia injection grid to complete the two-stage ammonia-flue gas mixing. The fully mixed flue gas enters the SCR denitrification reactor to complete the denitrification reduction reaction. As a further improvement of the present invention, the condensate obtained from the gas-liquid separation in step one is recovered through the condensate delivery pipe; when the buffer tank is arranged at a high position, the condensate is delivered by gravity flow based on the liquid level difference, and part of the condensate is sent to the ammonia water evaporator main pipeline; when arranged at a low position, the condensate is delivered to the ammonia water storage tank by pressurization through the ammonia delivery pump.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention introduces the ammonia-containing tail gas volatilized from the ammonia storage tank into the SCR denitrification system as a denitrification agent for resource utilization. This not only avoids the environmental pollution and harm to human health caused by the unorganized emission of ammonia-containing tail gas, but also achieves tail gas recovery and utilization based on the existing negative pressure working condition of SCR denitrification. There is no need to add additional power equipment such as exhaust fans, resulting in low equipment investment and strong adaptability.

[0018] 2. This invention recovers ammonia-containing tail gas from ammonia storage tank to participate in the denitrification reaction, replacing part of the amount of fresh ammonia water added, effectively reducing ammonia water consumption and significantly lowering the daily reagent operating costs of the SCR denitrification system.

[0019] 3. This invention uses two exhaust gas delivery paths. Under normal operating conditions, the ammonia-containing exhaust gas is directly sent into the denitrification flue gas pipeline, avoiding the problem of ammonia corroding the dilution fan. When the exhaust gas volume is too large, it automatically switches to the dilution fan inlet bypass for drainage. It has strong adaptability to operating conditions and reliable system operation.

[0020] 4. This invention forms a multi-layered safety system by using a buffer tank for pressure buffering, a storage tank for pressure detection, and valve interlocking for regulation, combined with a breather valve for extreme operating conditions to provide safety backup. This system can stabilize the operating pressure inside the tank, improve equipment safety, and achieve full-process interlocking automatic control, reducing manual operation and lowering the workload of on-site maintenance. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the connection structure of the various components of the present invention; Figure 3 This is a schematic diagram of the connection between the flue gas duct and the mixing pipe, as well as the injection assembly, according to the present invention. Figure 4 This is a cross-sectional view of the flue gas duct and mixing pipe of the present invention.

[0022] In the diagram: 1. Ammonia storage tank; 2. SCR denitrification reactor; 3. Mixing pipe; 4. Flue gas duct; 5. Injection assembly; 51. Gas delivery pipe; 52. Nozzle; 6. Ammonia injection grid; 7. Booster fan; 8. Dilution air supply unit; 81. Dilution air inlet pipe; 82. Dilution air outlet pipe; 83. Dilution fan; 9. Buffer tank; 10. Tail gas delivery main pipe; 11. First delivery branch; 12. Bypass delivery branch; 13. Ammonia water pipe; 14. Ammonia water pump; 15. Condensate collection... 16. Vent valve; 17. Condensate delivery pipe; 171. First branch section; 172. Second branch section; 18. Ammonia pump one; 19. Pressure transmitter; 20. Safety valve; 21. Flow control valve one; 22. Flow control valve two; 23. Flow control valve three; 24. Level gauge; 25. Ammonia evaporator; 27. Ammonia pump two; 28. Breather valve; 29. ​​Ammonia recovery branch pipe one; 30. Ammonia recovery branch pipe two; 31. Main ammonia delivery pipe; 32. Ammonia branch pipe. Detailed Implementation

[0023] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] The present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Please see Figure 1-4 The present invention provides an ammonia water storage tank tail gas treatment device for SCR denitrification, including an ammonia water storage tank 1, a buffer tank 9, an SCR denitrification reactor 2, a mixing pipe 3 located at the inlet end of the SCR denitrification reactor 2, a flue gas pipe 4 connected to the inlet end of the mixing pipe 3, an injection assembly 5 located in the flue gas pipe 4, an ammonia injection grid 6 connected to the mixing pipe 3, a booster fan 7 connected to the outlet end of the SCR denitrification reactor 2, and a dilution air supply unit 8. The ammonia storage tank 1 is equipped with a tail gas conveying main pipe 10 and an ammonia water pipe 13. The exhaust port at the top of the ammonia storage tank 1 is connected to the air inlet of the buffer tank 9 through the tail gas conveying main pipe 10. The air outlet of the buffer tank 9 is connected to the injection assembly 5 in the flue gas pipeline 4 through the first conveying branch 11. The ammonia water pipe 13 is connected to external ammonia water through the ammonia water pump 14. The top of the ammonia storage tank 1 is also provided with a bypass conveying branch 12. The output end of the bypass conveying branch 12 is connected to the dilution air supply unit 8, and the outlet of the dilution air supply unit 8 is connected to the ammonia spraying grid 6 in the mixing pipe 3. The bottom of the buffer tank 9 is provided with a condensate collection port 15, which is connected to the inside of the ammonia storage tank 1 through a condensate delivery pipe 17. A vent valve 16 is provided on the condensate collection port 15. The buffer tank 9 and the ammonia storage tank 1 have two relative layout positions: the first layout position is that the liquid level of the buffer tank 9 is higher than that of the ammonia storage tank 1, and the condensation conveying pipe 17 relies on the liquid level difference to achieve gravity flow of condensed ammonia back to the ammonia storage tank 1; the second layout position is that the liquid level of the buffer tank 9 is lower than that of the ammonia storage tank 1, and the condensation conveying pipe 17 is equipped with an ammonia pump 18 and a liquid level gauge 24, relying on the power of the pump body to transport condensed ammonia to the ammonia storage tank 1. The ammonia storage tank 1 is equipped with a pressure transmitter 19 and a breather valve 28. The pressure transmitter 19 is interlocked with the on / off and flow regulation structures of the first conveying branch 11 and the bypass conveying branch 12.

[0028] Optionally, flow regulating valve 21 and flow regulating valve 22 are respectively installed on the exhaust gas conveying main pipe 10 and the bypass conveying branch pipe 12 to regulate the on / off state of the pipeline and the conveying flow rate.

[0029] To ensure stable operating pressure in ammonia storage tank 1, a pressure transmitter 19 is installed on the top of the ammonia tank. The pressure transmitter 19 detects pressure and interlocks with the flow regulating valve 21 on the tail gas delivery main pipe 10 of ammonia storage tank 1, controlling the internal pressure of the ammonia tank within the range of -200Pa to 1000Pa. When the internal pressure is below -200Pa, the opening of the flow regulating valve 21 is reduced to decrease the amount of tail gas extracted; when the internal pressure is above 1000Pa, the opening of the flow regulating valve 21 is increased to increase the amount of tail gas discharged. To ensure the safe operation of the ammonia tank, a breather valve 28 is installed on the top of the ammonia tank. When the pressure inside the tank is lower than -298pa, the breather valve 28 automatically opens to introduce air into the tank to prevent the tank from collapsing due to negative pressure. When the pressure inside the tank is higher than 1765pa, the breather valve 28 automatically vents air to release pressure, meeting the equipment safety protection requirements under extreme working conditions.

[0030] Optionally, the buffer tank 9 is equipped with a safety valve 20; when the buffer tank 9 is in the second deployment position, the level gauge 24 is interlocked with the vent valve 16 and the ammonia transfer pump 18 to start and stop.

[0031] In this optional scheme, the ammonia-containing tail gas discharged from the ammonia storage tank 1 first enters the buffer tank 9 for pressure stabilization, buffering and gas-liquid separation, and then is sent into the negative pressure flue gas pipeline 4 at the front end of the SCR reactor to effectively suppress pressure fluctuations. A safety valve 20 is installed on the top of the buffer tank 9 for overpressure relief to ensure the safe use of the buffer tank 9.

[0032] During operation, condensate will naturally precipitate inside the buffer tank 9. This condensate is high-concentration ammonia water and has reuse value. Therefore, a vent valve 16 is installed at the bottom of the buffer tank 9, and the condensate is transported to the ammonia water storage tank 1 for reuse through the condensate delivery pipe 17 and the ammonia pump 18. The buffer tank 9 is equipped with a level gauge 24 for monitoring the liquid accumulation in the tank and a safety pressure relief component for overpressure protection. The level gauge 24 and the vent valve 16 on the condensate delivery pipe 17 are interlocked to start and stop, and the discharge and return of condensate are automatically controlled according to the liquid level in the tank.

[0033] Optionally, the injection assembly 5 includes an air supply pipe 51 and a plurality of nozzles 52. The plurality of nozzles 52 are evenly distributed along the inside of the flue gas duct 4. A through hole is provided on the outer wall of the flue gas duct 4 corresponding to the position of each nozzle 52. An air supply pipe 51 is provided on the outside of the flue gas duct 4 corresponding to the position of the through hole. The air supply pipe 51 is connected to the outlet end of the first conveying branch 11.

[0034] Optionally, the spray direction of several nozzles 52 is arranged at an angle opposite to the flow direction of flue gas inside the flue gas duct 4.

[0035] In this optional scheme, the angle between the nozzle 52 and the flue gas duct 4 is 15°-75°. By spraying the nozzle 52 at the opposite angle, the turbulence of the flue gas is used to enhance the mixing of ammonia and flue gas, shorten the mixing distance, improve the mixing efficiency of tail gas and flue gas, and improve the resource utilization rate of ammonia water tail gas.

[0036] Optionally, the dilution air supply unit 8 includes a dilution air inlet pipe 81, a dilution air outlet pipe 82, and a dilution fan 83. The dilution air inlet pipe 81 and the dilution air outlet pipe 82 are respectively connected to the inlet end and the outlet end of the dilution fan 83. A flow regulating valve 23 is installed on the dilution air inlet pipe 81. The flow regulating valve 23 is interlocked with the pressure transmitter 19 on the top of the ammonia storage tank 1, which can match the bypass tail gas flow ratio in real time.

[0037] Optionally, it also includes an ammonia evaporator 25 connected to the ammonia storage tank 1. The ammonia storage tank 1 and the ammonia evaporator 25 are connected through an ammonia conveying main pipe 31. An ammonia conveying pump 27 is provided on the ammonia conveying main pipe 31. The gas outlet of the ammonia evaporator 25 is connected to the dilution gas outlet pipe 82.

[0038] In this embodiment, the ammonia water in the ammonia water storage tank 1 is sent to the ammonia water evaporator 25 by the ammonia pump 27. After evaporation and vaporization, ammonia gas is generated and flows into the dilution outlet pipe 82 to mix with the ammonia-containing tail gas. The mixture is then sent to the ammonia injection grid 6 to participate in the denitrification reaction.

[0039] To further utilize the ammonia-containing tail gas from ammonia storage tank 1 and improve its operational safety, when the internal pressure of ammonia storage tank 1 exceeds 1500 Pa, the system interlock opens the flow regulating valve 22 on the bypass conveying branch 12 and simultaneously reduces the opening of the flow regulating valve 23 on the dilution air duct. This fully utilizes the negative pressure suction of the dilution fan 83 to draw the overpressure tail gas from ammonia storage tank 1 to the ammonia injection grid 6, where it is evenly injected into the flue gas duct before the SCR reactor to participate in denitrification. When the pressure inside ammonia storage tank 1 drops below 1000 Pa, the flow regulating valve 22 is closed, and the flow regulating valve 23 is restored to its normal operating opening, returning the system to its normal tail gas treatment mode.

[0040] Optionally, the condensation conveying pipe 17 is provided with a first branch section 171 and a second branch section 172. The first branch section 171 is connected to the ammonia storage tank 1, and the second branch section 172 is connected to the ammonia conveying main pipe 31 of the ammonia evaporator 25. The ammonia conveying main pipe 31 is provided with an ammonia recovery branch pipe 29 connected to the ammonia storage tank 1. The first branch section 171 is connected to an ammonia recovery branch pipe 30. The other end of the ammonia recovery branch pipe 30 is connected to the ammonia recovery branch pipe 29. The ammonia pump 18 is mounted on the ammonia recovery branch pipe 30. The ammonia conveying main pipe 31 and the ammonia recovery branch pipe 30 are also connected by an ammonia branch pipe 32. In this optional solution, the above design can be adapted to two different deployment conditions of buffer tank 9, enabling graded and differentiated recovery of condensate under different installation scenarios: When in the first deployment position, the condensation conveying pipe 17 relies on the liquid level difference to achieve the gravity flow back of the condensed ammonia water. At this time, the first diversion section 171 is open, and the condensed ammonia water separated from the buffer tank 9 can be gravity-flowed into the ammonia water storage tank 1 for resource utilization as raw material for denitrification ammonia supply. When in the second deployment position, the ammonia pump 18 is in normal working condition. The vent valve 16 of the second diversion section 172 is closed, and the vent valve 16 of the first diversion section 171 and the shut-off valve of the ammonia water recovery branch pipe 20 are opened. After the level gauge 24 detects that the liquid level of the buffer tank 9 reaches the threshold, the ammonia pump 18 is interlocked and started. The condensed ammonia water in the buffer tank 9 is sequentially sent back to the ammonia water storage tank 1 through the first diversion section 171, the ammonia water recovery branch pipe 20, and the ammonia water recovery branch pipe 29, thus completing the recovery of the condensed ammonia water in the buffer tank 9. Based on the above pathway, ammonia water can be supplied to the ammonia water evaporator 25 through three implementation methods: First implementation method: Close the shut-off valve of the first diversion section 171, the section connecting the ammonia water recovery branch pipe 20 and the ammonia water recovery branch pipe 19, open the shut-off valve on the ammonia delivery branch pipe 32, and deliver the ammonia water in the ammonia water storage tank 1 to the ammonia water evaporator 25 through the ammonia delivery pump 18. In this implementation method, the ammonia delivery pump 18 is used as the main working pump, and the ammonia delivery pump 27 is in standby mode, realizing the dual pump one-in-use and one-in-standby operation mode; the ammonia delivery pump 18 independently completes the denitrification ammonia supply operation, while the ammonia delivery pump 27 is on standby, flexibly switching the ammonia supply path, avoiding the problem of easy failure when a single pump operates at high load for a long time, and ensuring the continuity of denitrification ammonia supply. Second implementation method: Keep the first diversion section 171 open, close the shut-off valve of the section connecting the ammonia water recovery branch pipe 20 and the ammonia water recovery branch pipe 129, and send part of the condensed ammonia water recovered in the buffer tank 9 through the ammonia pump 18 to the ammonia water evaporator 25 via the first diversion section 171 and the ammonia water recovery branch pipe 20 ammonia water supply branch pipe 32. The condensed ammonia water recovered in the buffer tank 9 is directly used as the denitrification reducing agent, realizing the on-site resource recycling of waste ammonia water, greatly saving the amount of fresh ammonia water used, and achieving significant energy saving and consumption reduction. At the same time, the backup pump ensures operation without the risk of downtime. Third implementation method: When the ammonia pump 18 condenses ammonia water in the buffer tank 9 in the first diversion section 171 and recovers it to the ammonia water storage tank 1, the ammonia pump 27 can work independently at the same time, drawing fresh ammonia water from the ammonia water storage tank 1 and sending it to the ammonia water evaporator 25, ensuring the supply of reducing agent to the denitrification system independently. The two pumps work together to complete the two core processes of condensate recovery and denitrification ammonia supply simultaneously without interfering with each other, greatly improving the operating efficiency of the whole set of equipment, while retaining the ability to be mutually redundant, so that the system can be quickly switched if either pump fails.

[0041] When ammonia pump 18 malfunctions or is not needed in other situations, the first diversion section 171 is closed, the shut-off valve of ammonia recovery branch pipe 2 30 is closed, ammonia pump 18 is shut down for maintenance, and ammonia pump 2 27 and the vent valve 16 on the second diversion section 172 are started to take over the recovery of condensed ammonia in buffer tank 9 from the first diversion section 171. The condensed ammonia in buffer tank 9 is sequentially sent back to ammonia storage tank 1 through the second diversion section 172, the main ammonia conveying pipe 31, and the ammonia recovery branch pipe 29, thus completing the recovery of condensed ammonia in buffer tank 9 and realizing the switching of one pump for use and one for standby. Based on the above pathway, ammonia water can be supplied to the ammonia water evaporator 25 through two implementation methods: First implementation method: Close the shut-off valve on the ammonia water recovery branch pipe 29, open the shut-off valve on the pipeline connecting the ammonia main pipe 31 and the ammonia water evaporator 25, and send the condensed ammonia water in the buffer tank 9 through the second diversion section 172 and the ammonia main pipe 31 to the ammonia water evaporator 25 by the ammonia pump 27. When the ammonia pump 18 fails, the condensed ammonia water can still be used to continuously supply ammonia to the denitrification system after switching to the ammonia pump 27. There is no problem of machine shutdown and supply interruption throughout the process, which greatly improves the continuous operation capability and working condition adaptability of the device. Second implementation method: Close the vent valve 16 on the second diversion section 172 and the shut-off valve on the ammonia water recovery branch pipe 29, open the shut-off valve on the pipeline connecting the ammonia water evaporator 25 and the ammonia water storage tank 1 on the ammonia water main pipe 31, and transport the ammonia water in the ammonia water storage tank 1 to the ammonia water evaporator 25 through the ammonia water main pipe 31 via the ammonia water pump 27. This is suitable for the working condition of insufficient condensed ammonia water storage, and stably supplies ammonia water of standard concentration to ensure that the denitrification effect is stable and meets the standard.

[0042] In this device, ammonia pump 18 and ammonia pump 27 form a complete redundant pumping system with one pump in operation and one on standby. The two pumps can switch between being the primary pump and the standby pump. During normal operation, ammonia pump 18 is the primary pump for recovering condensed ammonia from buffer tank 9, while ammonia pump 27 is on standby. When ammonia pump 18 fails for maintenance, ammonia pump 27 can seamlessly switch to being the primary pump, taking over all condensate recovery operations from buffer tank 9. Both pumps have bidirectional transport capabilities, capable of both pumping condensed ammonia from buffer tank 9 and recovering it to… Ammonia storage tank 1 can also transport condensed ammonia water from buffer tank 9 or fresh ammonia water from ammonia storage tank 1 to ammonia evaporator 25 for denitrification reaction; the two pumps can operate independently or work in tandem, switching different delivery paths by relying on the shut-off valves of each branch, and eliminating the hidden dangers of system shutdown, condensate accumulation, and denitrification reducing agent interruption caused by single pump shutdown by relying on the one-in-use-one-outstanding structure, taking into account both the recycling and utilization of condensed ammonia water resources and the continuous and stable supply of ammonia to the denitrification system, significantly improving the operational reliability and working condition adaptability of the entire unit.

[0043] A method for treating the tail gas of an ammonia storage tank 1 used in SCR denitrification includes the following steps: Step 1: The pressure inside the ammonia storage tank 1 is monitored in real time by the pressure transmitter 19. The ammonia-containing tail gas generated by the ammonia storage tank 1 is sent to the buffer tank 9 through the tail gas conveying main pipe 10 to complete the pressure buffering and gas-liquid separation. Step 2: When the ammonia storage tank 1 is in the normal pressure range, close the bypass conveying branch 12 and only open the first conveying branch 11. The pressure-stabilized ammonia-containing tail gas is conveyed to the injection assembly 5 through the first conveying branch 11 and sprayed into the flue gas pipeline 4 in reverse by the injection assembly 5 to complete the initial uniform mixing with the flue gas to be denitrified. Step 3: When the internal pressure of ammonia storage tank 1 exceeds the standard, the bypass conveying branch 12 is opened by interlock and the air flow of the dilution air supply unit 8 is adjusted to introduce the excess ammonia-containing tail gas from ammonia storage tank 1 into the dilution air supply unit 8. At the same time, the denitrified ammonia gas produced by ammonia evaporator 25 is incorporated into the dilution air supply unit 8 and mixed with the bypass ammonia-containing tail gas for dilution. Step 4: The diluted and mixed ammonia-air mixture is evenly distributed into the flue gas through the ammonia injection grid 6 in the mixing pipe 3. The flue gas passes through the upstream injection component 5 and the downstream ammonia injection grid 6 to complete the two-stage ammonia-flue gas mixing. The fully mixed flue gas enters the SCR denitrification reactor 2 to complete the denitrification reduction reaction. In step one, the condensate obtained from the gas-liquid separation in buffer tank 9 is recovered through condensate delivery pipe 17. When buffer tank 9 is arranged at a high level, the condensate is delivered by gravity flow based on the liquid level difference, and part of the condensate is sent to the ammonia water evaporator 25 and the ammonia delivery main pipe 31. When arranged at a low level, the condensate is pressurized and delivered to ammonia water storage tank 1 through ammonia delivery pump 18.

[0044] In step two, when the ammonia storage tank 1 is in the normal pressure range of -200Pa to 1000Pa, the bypass conveying branch 12 is closed and only the first conveying branch 11 is opened; the pressure-stabilized ammonia-containing tail gas is conveyed to the injection assembly 5 through the first conveying branch 11, and then injected into the flue gas pipeline 4 in reverse by the injection assembly 5 to complete the initial uniform mixing with the flue gas to be denitrified. In step three, when the internal pressure of ammonia storage tank 1 exceeds the standard and is higher than 1500Pa, the bypass delivery branch 12 is interlocked and the air intake flow of the dilution air supply unit 8 is adjusted accordingly; the excess ammonia-containing tail gas from ammonia storage tank 1 is introduced into the dilution air supply unit 8, and at the same time, the denitrified ammonia gas produced by ammonia evaporator 25 is incorporated into the dilution air supply unit 8, and mixed and diluted with the bypass ammonia-containing tail gas to form a uniform ammonia-air mixture.

[0045] The present invention has been described by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvement made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, shall be within the protection scope of the present invention.

Claims

1. A tail gas treatment device for ammonia storage tank used in SCR denitrification, characterized in that: It includes an ammonia storage tank (1), a buffer tank (9), an SCR denitrification reactor (2), a mixing pipe (3) located at the inlet end of the SCR denitrification reactor (2), a flue gas duct (4) connected to the inlet end of the mixing pipe (3), an injection assembly (5) located in the flue gas duct (4), an ammonia injection grid (6) connected to the mixing pipe (3), a booster fan (7) connected to the outlet end of the SCR denitrification reactor (2), and a dilution air supply unit (8). The ammonia storage tank (1) is equipped with a tail gas conveying main pipe (10) and an ammonia water pipe (13). The exhaust port at the top of the ammonia storage tank (1) is connected to the air inlet of the buffer tank (9) through the tail gas conveying main pipe (10). The air outlet of the buffer tank (9) is connected to the injection assembly (5) in the flue gas pipeline (4) through the first conveying branch (11). The ammonia water pipe (13) is connected to external ammonia water through the ammonia water pump (14). The top of the ammonia storage tank (1) is also provided with a bypass conveying branch (12), the output end of the bypass conveying branch (12) is connected to the dilution air supply unit (8), and the outlet of the dilution air supply unit (8) is connected to the ammonia spray grid (6) in the mixing pipe (3). The bottom of the buffer tank (9) is provided with a condensate collection port (15), which is connected to the inside of the ammonia storage tank (1) through a condensate delivery pipe (17). A vent valve (16) is provided on the condensate collection port (15). The buffer tank (9) and the ammonia storage tank (1) have two relative layout positions: the first layout position is that the liquid level of the buffer tank (9) is higher than that of the ammonia storage tank (1), and the condensation conveying pipe (17) relies on the liquid level difference to realize the gravity flow of condensed ammonia back to the ammonia storage tank (1); the second layout position is that the liquid level of the buffer tank (9) is lower than that of the ammonia storage tank (1), and the condensation conveying pipe (17) is equipped with an ammonia pump (18) and a level gauge (24), and relies on the power of the pump body to transport condensed ammonia to the ammonia storage tank (1). The ammonia storage tank (1) is equipped with a pressure transmitter (19) and a breather valve (28). The pressure transmitter (19) is interlocked with the first conveying branch (11) and the bypass conveying branch (12) for on / off control and flow regulation.

2. The tail gas treatment device for an ammonia storage tank used in SCR denitrification according to claim 1, characterized in that: The exhaust gas conveying main pipe (10) and the bypass conveying branch pipe (12) are respectively equipped with flow regulating valve one (21) and flow regulating valve two (22) for regulating the opening and closing of the pipeline and the conveying flow.

3. The tail gas treatment device for an ammonia storage tank used in SCR denitrification according to claim 1, characterized in that: The injection assembly (5) includes an air supply pipe (51) and several nozzles (52). The nozzles (52) are evenly arranged inside the flue gas duct (4). A through hole is provided on the outer wall of the flue gas duct (4) corresponding to the position of each nozzle (52). An air supply pipe (51) is provided on the outside of the flue gas duct (4) corresponding to the position of the through hole. The air supply pipe (51) is connected to the outlet end of the first conveying branch (11).

4. The tail gas treatment device for an ammonia storage tank used in SCR denitrification according to claim 3, characterized in that: The spray direction of several nozzles (52) is arranged at an angle opposite to the flow direction of flue gas inside the flue gas duct (4).

5. The tail gas treatment device for an ammonia storage tank used in SCR denitrification according to claim 1, characterized in that: The buffer tank (9) is equipped with a safety valve (20); when the buffer tank (9) is in the second deployment position, the level gauge (24) is interlocked with the vent valve (16) and the ammonia pump (18) to start and stop.

6. The tail gas treatment device for an ammonia storage tank used in SCR denitrification according to claim 1, characterized in that: The dilution air supply unit (8) includes a dilution air inlet pipe (81), a dilution air outlet pipe (82), and a dilution fan (83). The dilution air inlet pipe (81) and the dilution air outlet pipe (82) are respectively connected to the inlet end and the outlet end of the dilution fan (83). A flow regulating valve three (23) is installed on the dilution air inlet pipe (81). The flow regulating valve three (23) is interlocked with the pressure transmitter (19) on the top of the ammonia storage tank (1).

7. The tail gas treatment device for an ammonia storage tank used in SCR denitrification according to claim 6, characterized in that: It also includes an ammonia evaporator (25) connected to the ammonia storage tank (1). The ammonia storage tank (1) and the ammonia evaporator (25) are connected through an ammonia transfer main pipe (31). An ammonia transfer pump (27) is provided on the ammonia transfer main pipe (31). The gas outlet of the ammonia evaporator (25) is connected to the dilution gas outlet pipe (82).

8. The tail gas treatment device for an ammonia storage tank used in SCR denitrification according to claim 7, characterized in that: The condensation conveying pipe (17) is provided with a first branch section (171) and a second branch section (172). The first branch section (171) is connected to the ammonia storage tank (1), and the second branch section (172) is connected to the ammonia conveying main pipe (31) of the ammonia evaporator (25). The ammonia conveying main pipe (31) is provided with an ammonia recovery branch pipe 1 (29) connected to the ammonia storage tank (1). The first branch section (171) is connected to an ammonia recovery branch pipe 2 (30). The other end of the ammonia recovery branch pipe 2 (30) is connected to the ammonia recovery branch pipe 1 (29). The ammonia pump 1 (18) is installed on the ammonia recovery branch pipe 2 (30). The ammonia conveying main pipe (31) and the ammonia recovery branch pipe 2 (30) are also connected by an ammonia conveying branch pipe (32).

9. A method for treating the tail gas of an ammonia storage tank for SCR denitrification, comprising the tail gas treatment device for an ammonia storage tank for SCR denitrification as described in any one of claims 1 to 8, characterized in that: Includes the following steps, Step 1: The pressure inside the ammonia storage tank (1) is monitored in real time by the pressure transmitter (19). The ammonia-containing tail gas generated by the ammonia storage tank (1) is sent to the buffer tank (9) through the tail gas conveying main pipe (10) to complete the pressure buffering and gas-liquid separation. Step 2: When the ammonia storage tank (1) is in the normal pressure range, close the bypass conveying branch (12) and only open the first conveying branch (11). The pressure-stabilized ammonia-containing tail gas is conveyed to the injection assembly (5) through the first conveying branch (11) and sprayed into the flue gas pipeline (4) in reverse by the injection assembly (5) to complete the initial uniform mixing with the flue gas to be denitrified. Step 3: When the internal pressure of the ammonia storage tank (1) exceeds the standard, the bypass delivery branch (12) is opened by interlock and the air intake flow of the dilution air supply unit (8) is adjusted to introduce the excess ammonia-containing tail gas from the ammonia storage tank (1) into the dilution air supply unit (8). At the same time, the denitrified ammonia gas produced by the ammonia evaporator (25) is incorporated into the dilution air supply unit (8) and mixed with the bypass ammonia-containing tail gas for dilution. Step 4: The diluted and mixed ammonia-air mixture is evenly distributed into the flue gas through the ammonia injection grid (6) in the mixing pipe (3). The flue gas passes through the upstream injection component (5) and the downstream ammonia injection grid (6) to complete the two-stage ammonia-flue gas mixing. The fully mixed flue gas enters the SCR denitrification reactor (2) to complete the denitrification reduction reaction.

10. A method for treating tail gas from an ammonia storage tank for SCR denitrification according to claim 9, characterized in that: In step one, the condensate obtained from the gas-liquid separation of the buffer tank (9) is recovered through the condensate delivery pipe (17); when the buffer tank (9) is arranged at a high position, the condensate is delivered by gravity flow based on the liquid level difference, and part of the condensate is sent to the ammonia water evaporator (25) and the ammonia delivery main pipe (31); when arranged at a low position, the condensate is pressurized and delivered to the ammonia water storage tank (1) through the ammonia delivery pump (18).

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