Boiler flue gas denitration system
Patent Information
- Application Number
- CN202522009982.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-18
- Publication Date
- 2026-09-15
- Estimated Expiration
- 2035-09-18
AI Technical Summary
[0002]现有锅炉烟气脱硝技术中，单一采用选择性非催化还原（SNCR）技术时，因需在高温炉膛内喷射还原剂，反应温度窗口狭窄，脱硝效率仅能达到30%-70%，且为保证达标排放常需过量喷射氨水，导致氨逃逸率升高，未反应的氨气与烟气中的二氧化硫结合生成硫酸氢铵，易造成尾部烟道和空气预热器堵塞、腐蚀
两级预处理显著降低烟气含尘量，避免粉尘对催化剂的磨损和中毒，延长催化剂使用寿命；SNCR与SCR的组合工艺发挥了前者低成本初步脱硝和后者高效深度净化的优势，协同脱硝效率可达90%以上，解决了单一技术效率不足或成本过高的问题；密闭式氨水供给与空气稀释系统减少了氨气泄漏风险，配合喷淋组件的精准喷射，有效控制氨逃逸率。
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Abstract
Description
Technical Field
[0001] This utility model relates to the field of boiler flue gas denitrification, and specifically to a boiler flue gas denitrification system. Background Technology
[0002] In existing boiler flue gas denitrification technologies, the use of selective non-catalytic reduction (SNCR) alone results in a narrow reaction temperature window due to the need to inject a reducing agent into the high-temperature furnace, leading to a denitrification efficiency of only 30%-70%. Furthermore, to ensure compliance with emission standards, excessive ammonia injection is often required, increasing ammonia escape rates. Unreacted ammonia combines with sulfur dioxide in the flue gas to form ammonium bisulfate, easily causing blockage and corrosion in the tail flue and air preheater. While selective catalytic reduction (SCR) technology can achieve denitrification efficiencies of over 90%, the catalyst is susceptible to abrasion and poisoning from dust in the flue gas. Especially when pretreatment dust removal is incomplete, heavy metals and particulate matter from fly ash adhere to the catalyst surface, causing a rapid decline in its activity and requiring frequent replacement to maintain performance.
[0003] In actual operation, the existing system has the following problems: the pretreatment relies on a single dust removal device, which makes it difficult to remove fine particulate matter, resulting in ash accumulation in the SCR reactor, high air preheater blockage rate, and frequent system shutdowns; the single SNCR technology has a narrow reaction temperature window and low efficiency, and excessive ammonia injection can easily cause ammonia escape and equipment corrosion; the single SCR technology lacks effective pretreatment, and the catalyst is easily affected by dust, requiring frequent replacement; the exhaust gas detection is difficult to provide real-time feedback, which can easily lead to resource waste or emissions exceeding standards. Utility Model Content
[0004] This invention provides a boiler flue gas denitrification system to address the problems of existing technologies.
[0005] The objective of this utility model can be achieved through the following technical solution: A boiler flue gas denitrification system includes a pretreatment unit, a denitrification reaction unit, a tail gas detection unit, an ammonia water supply unit, an air intake unit, and an ammonia-air mixer, which are sequentially and sealed along the flue gas flow direction; the pretreatment unit is located at the air intake end of the denitrification reaction unit and includes an electrostatic precipitator and a bag filter; the denitrification reaction unit includes a primary SNCR reaction zone and a secondary SCR reaction zone arranged sequentially, and both the primary SNCR reaction zone and the secondary SCR reaction zone are equipped with spray components; the secondary SCR reaction zone has a honeycomb denitrification catalyst layer inside, and a catalyst regeneration component is located outside the secondary SCR reaction zone; the tail gas detection unit is located at the air outlet end of the denitrification reaction unit; the ammonia water supply unit sends ammonia water and air into the ammonia-air mixer for mixing; the ammonia-air mixer sends the mixed liquid into the ammonia injection system; and the ammonia injection system is connected to the spray components.
[0006] In a further improvement, the ammonia supply unit includes an anhydrous ammonia tanker, an ammonia compressor, and an anhydrous ammonia storage tank connected in sequence by pipelines. The air intake unit includes a dilution fan, and the output end of the dilution fan and the output end of the anhydrous ammonia storage tank are connected to an ammonia-air mixer by pipelines.
[0007] In a further improvement, the spray assembly is provided with three layers, each layer including 4-8 sets of adjustable nozzles, and each set of nozzles is equipped with a flow regulating valve.
[0008] In a further improvement, the number of honeycomb denitrification catalyst layers is 2-3 layers, and the catalyst pore size of the honeycomb denitrification catalyst layers is 5-8mm; the secondary SCR reaction zone is also provided with an airflow distribution plate, which is located below the honeycomb denitrification catalyst layers. A further improvement is that the catalyst regeneration component is a hot air purging device.
[0009] As a further improvement, the exhaust gas detection unit includes a nitrogen oxide concentration sensor and a flue gas flow sensor.
[0010] Compared with existing technologies, the beneficial effects of this utility model boiler flue gas denitrification system are as follows: Two-stage pretreatment significantly reduces the dust content in flue gas, avoids dust abrasion and poisoning of the catalyst, and extends the catalyst's service life; the combined process of SNCR and SCR leverages the advantages of the former's low-cost preliminary denitrification and the latter's efficient deep purification, achieving a synergistic denitrification efficiency of over 90%, solving the problems of insufficient efficiency or excessive cost of single technologies; the closed-loop ammonia water supply and air dilution system reduces the risk of ammonia leakage, and, in conjunction with the precise spraying of the spray components, effectively controls the ammonia escape rate. Attached Figure Description
[0011] Figure 1 This is a structural schematic diagram of the present invention. In the diagram, 1-Pretreatment unit, 11-Electrostatic precipitator, 12-Bag filter, 2-Denitrification reaction unit, 21-First-stage SNCR reaction zone, 22-Second-stage SCR reaction zone, 23-Spray assembly, 24-Honeycomb denitrification catalyst layer, 25-Catalyst regeneration assembly, 26-Airflow distribution plate, 3-Tail gas detection unit, 31-Nitrogen oxide concentration sensor, 32-Flue gas flow sensor, 5-Ammonia water supply unit, 51-Anhydrous ammonia tanker, 52-Ammonia compressor, 53-Anhydrous ammonia storage tank, 61-Dilution fan, 7-Ammonia and air mixer, 8-Ammonia injection system. Detailed Implementation
[0012] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model; unless otherwise expressly specified and limited, the terms "installed," "connected," and "joined" should be interpreted broadly, for example, they can refer to fixed connections or detachable connections, etc. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.
[0013] The following is a description of the embodiments and appendices. Figure 1 The technical solution of this utility model will be further described below.
[0014] Example 1 A boiler flue gas denitrification system includes a pretreatment unit 1, a denitrification reaction unit 2, a tail gas detection unit 3, an ammonia water supply unit 5, an air intake unit, and an ammonia-air mixer 7, which are sequentially and sealed along the flue gas flow direction. The pretreatment unit 1 is located at the air inlet of the denitrification reaction unit 2 and includes an electrostatic precipitator 11 and a bag filter 12. The denitrification reaction unit 2 includes a primary SNCR reaction zone 21 and a secondary SCR reaction zone 22 arranged sequentially. Each zone 22 is equipped with a spray assembly 23. The secondary SCR reaction zone 22 is equipped with a honeycomb denitrification catalyst layer 24, and the secondary SCR reaction zone 22 is equipped with a catalyst regeneration assembly 25 on the outside. The exhaust gas detection unit 3 is located at the outlet of the denitrification reaction unit 2. The ammonia water supply unit 5 sends ammonia water and the air intake unit sends air into the ammonia and air mixer 7 for mixing. The ammonia and air mixer 7 sends the mixed liquid into the ammonia injection system 8. The ammonia injection system 8 is connected to the spray assembly 23.
[0015] like Figure 1 As shown, the working principle of this utility model is as follows: High-efficiency denitrification is achieved through the organic integration of a pretreatment unit, a denitrification reaction unit, and a material supply system. Flue gas first enters the pretreatment unit, where an electrostatic precipitator uses a high-voltage electric field to charge and adsorb dust particles, initially removing most of the coarse dust. It then enters a bag filter, where fine particles are captured through the sieving and interception action of the fiber filter media, achieving a two-stage progressive dust removal process. The purified flue gas enters the primary SNCR reaction zone, where it undergoes a reduction reaction with ammonia water sprayed by the spray assembly under high-temperature conditions, converting some nitrogen oxides into nitrogen and water. The remaining nitrogen oxides enter the secondary SCR reaction zone with the flue gas, where they are further reduced on the surface of the honeycomb catalyst, achieving deep denitrification. The ammonia water supply unit delivers the reducing agent through a closed pipeline, which, after being diluted with air, is precisely distributed to each reaction zone by the ammonia injection system. The exhaust gas detection unit monitors emission indicators in real time, forming a complete closed-loop treatment system.
[0016] Two-stage pretreatment significantly reduces the dust content in flue gas, avoids dust abrasion and poisoning of the catalyst, and extends the catalyst's service life; the combined process of SNCR and SCR leverages the advantages of the former's low-cost preliminary denitrification and the latter's efficient deep purification, achieving a synergistic denitrification efficiency of over 90%, solving the problems of insufficient efficiency or excessive cost of single technologies; the closed-loop ammonia water supply and air dilution system reduces the risk of ammonia leakage, and, in conjunction with the precise spraying of the spray components, effectively controls the ammonia escape rate.
[0017] In a further preferred embodiment, the ammonia supply unit 5 includes an anhydrous ammonia tanker 51, an ammonia compressor 52, and an anhydrous ammonia storage tank 53 connected sequentially by pipelines. The air intake unit includes a dilution fan 61, and the output ends of the dilution fan 61 and the anhydrous ammonia storage tank 53 are connected to an ammonia-air mixer 7 via pipelines. The ammonia compressor transports anhydrous ammonia from the tanker to the storage tank, avoiding the volatilization losses associated with traditional atmospheric pressure storage. The dilution fan in the air intake unit provides clean air, which is thoroughly mixed with ammonia gas in the ammonia-air mixer, diluting the ammonia concentration to a safe range. The output pipelines of both units are connected to the mixer in tandem, achieving a stable supply and safe dilution of the reducing agent.
[0018] As a further preferred embodiment, the spray assembly 23 is provided with three layers, each layer including 4-8 sets of adjustable nozzles, and each set of nozzles is equipped with a flow regulating valve. The three-layer spray assembly is arranged three-dimensionally along the flue gas flow direction, and each layer of nozzles is independently controlled by the flow regulating valve, which can adjust the spray volume according to the temperature field and flue gas concentration distribution in different reaction zones. The adjustable nozzle design can optimize the atomization angle and coverage range, ensuring that the reducing agent and flue gas are in full contact within the reaction zone.
[0019] As a further preferred embodiment, the number of honeycomb denitrification catalyst layers 24 is 2-3 layers, and the catalyst pore size of the honeycomb denitrification catalyst layers 24 is 5-8 mm; the secondary SCR reaction zone 22 is also provided with an airflow distribution plate 26, which is located below the honeycomb denitrification catalyst layers 24. The multi-layer catalyst arrangement extends the reaction path, increases the contact probability between nitrogen oxides and the catalyst, and improves the denitrification efficiency; the airflow distribution plate effectively solves the problem of flue gas deviation in traditional reactors, avoiding catalyst wear caused by excessively high local flow velocity, or ash accumulation and blockage caused by excessively low flow velocity.
[0020] As a further preferred embodiment, the catalyst regeneration component 25 is a hot air purging device. The hot air purging function effectively maintains catalyst activity, reduces the decrease in catalytic efficiency caused by dust accumulation, and lowers the catalyst replacement frequency.
[0021] As a further preferred embodiment, the exhaust gas detection unit 3 includes a nitrogen oxide concentration sensor 31 and a flue gas flow sensor 32. The nitrogen oxide concentration sensor monitors the nitrogen oxide content in the flue gas after denitrification in real time, and the flue gas flow sensor records the volumetric flow rate of the flue gas. The data from both can be combined to calculate the actual nitrogen oxide emissions. The detection signal is fed back to the control system to dynamically adjust the ammonia injection volume.
[0022] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.
Claims
1. A boiler flue gas denitrification system, characterized in that, The system includes a pretreatment unit, a denitrification reaction unit, a tail gas detection unit, an ammonia supply unit, an air intake unit, and an ammonia-air mixer, all sequentially and sealed along the flue gas flow direction. The pretreatment unit is located at the air intake end of the denitrification reaction unit and includes an electrostatic precipitator and a bag filter. The denitrification reaction unit includes a primary SNCR reaction zone and a secondary SCR reaction zone arranged sequentially. Both the primary SNCR reaction zone and the secondary SCR reaction zone are equipped with spray components. The secondary SCR reaction zone has a honeycomb denitrification catalyst layer inside and a catalyst regeneration component outside. The tail gas detection unit is located at the air outlet end of the denitrification reaction unit. The ammonia supply unit supplies ammonia and the air intake unit supplies air into the ammonia-air mixer for mixing. The ammonia-air mixer sends the mixed liquid into an ammonia injection system, which is connected to the spray components.
2. The boiler flue gas denitrification system according to claim 1, characterized in that, The ammonia supply unit includes an anhydrous ammonia tanker, an ammonia compressor, and an anhydrous ammonia storage tank connected in sequence by pipelines. The air intake unit includes a dilution fan. The output end of the dilution fan and the output end of the anhydrous ammonia storage tank are connected to an ammonia-air mixer by pipelines.
3. The boiler flue gas denitrification system according to claim 1, characterized in that, The spray assembly has three layers, each layer including 4-8 sets of adjustable nozzles, and each set of nozzles is equipped with a flow regulating valve.
4. The boiler flue gas denitrification system according to claim 1, characterized in that, The number of honeycomb denitrification catalyst layers is 2-3 layers, and the catalyst pore size of the honeycomb denitrification catalyst layer is 5-8mm; the secondary SCR reaction zone is also provided with an airflow distribution plate, which is located below the honeycomb denitrification catalyst layer.
5. The boiler flue gas denitrification system according to claim 1, characterized in that, The catalyst regeneration component is a hot air purging device.
6. The boiler flue gas denitrification system according to claim 1, characterized in that, The exhaust gas detection unit includes a nitrogen oxide concentration sensor and a flue gas flow sensor.