SCR denitration conversion integrated device and smelting flue gas acid making system
By using an integrated SCR denitrification and conversion device to remove NOx and convert SO2 at 400℃~450℃, the problems of high energy consumption and corrosion in existing technologies have been solved, achieving efficient and low-energy flue gas treatment and improving the quality of finished acid.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHINA NERIN ENGINEERING CO LTD
- Filing Date
- 2025-05-30
- Publication Date
- 2026-05-29
AI Technical Summary
Existing flue gas treatment devices consume a lot of energy, and the products of the reaction between NOx and SO2 in the flue gas are prone to corroding the equipment, making it difficult to achieve efficient removal of NOx and SO2 with low energy consumption.
The integrated SCR denitrification and conversion device combines SCR denitrification components and conversion components to first remove NOx at 400℃~450℃ and then convert SO2, avoiding secondary heating. It utilizes the heat released by the SCR denitrification reaction to reduce energy consumption and optimizes reaction conditions through specific catalysts and heat exchangers.
It achieves a NOx removal rate of 90%~98%, improves SO2 conversion rate, reduces energy consumption, avoids the reaction of NOx and SO2 to generate corrosive substances, and improves the quality of the finished acid.
Smart Images
Figure CN224292938U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of flue gas purification and chemical technology, specifically to an integrated SCR denitrification and conversion device and a smelting flue gas acid production system. Background Technology
[0002] At present, nitrogen oxides (NOx) in industrial flue gas x SO2 is one of the main causes of serious pollution problems such as acid rain, smog, and photochemical smog. Based on this, related technologies first use conversion components to convert and remove SO2 from industrial flue gas, resulting in nitrate-containing flue gas. Then, a high-efficiency selective catalytic reduction (SCR) denitrification component is used to remove NO from the nitrate-containing flue gas. x While removing NO through a process can ensure the final chimney emissions meet environmental standards, it requires high energy consumption and results in higher NO content in the flue gas. x It reacts with SO2, and the resulting products are highly corrosive to equipment. Therefore, developing a low-energy, high-efficiency flue gas treatment device and method that can meet environmental standards for emissions is currently one of the challenges. Utility Model Content
[0003] This application aims to at least partially address one of the technical problems in related technologies. Therefore, one objective of this application is to provide an integrated SCR denitrification and conversion device and a smelting flue gas acid production system, utilizing the integrated SCR denitrification and conversion device of this application to treat NO in nitrate-containing flue gas. x When removing SO2 and converting SO2, the energy consumption is low and the efficiency is high; at the same time, when using the integrated SCR denitrification and conversion device of this application in the smelting flue gas acid production system, the energy consumption is low and the quality of the finished acid product is high.
[0004] The first aspect of this application proposes an integrated SCR denitrification and conversion device, comprising: an SCR denitrification component for removing nitrogen oxides from nitrifying flue gas at 400℃~450℃ to obtain a first flue gas; and a conversion component connected to the SCR denitrification component for converting sulfur dioxide in the first flue gas into sulfur trioxide to obtain a second flue gas.
[0005] This integrated unit combines an SCR denitrification component and a conversion component to first remove NO from the nitrification-containing flue gas. x Then, SO2 is converted, avoiding secondary heating of the nitrate-containing gas, greatly reducing energy consumption, while NO... x The removal rate can reach 90%~98%, avoiding NO in flue gas x It affects the conversion of SO2, thereby further improving the SO2 conversion rate.
[0006] In addition, the SCR denitrification and conversion integrated device according to the above embodiments of this application may also have the following additional technical features:
[0007] In some embodiments of this application, the SCR denitrification assembly includes:
[0008] A denitrification heat exchanger is used to heat the nitrate-containing flue gas to obtain a third flue gas;
[0009] A liquid ammonia supply unit is used to supply liquid ammonia;
[0010] A mixer, connected to the denitrification heat exchanger and the liquid ammonia supply unit, is used to mix the liquid ammonia and the third flue gas to obtain a mixture.
[0011] An SCR denitrification reactor, connected to the mixer, is used to remove nitrogen oxides from the mixture to obtain the first flue gas. This helps to reduce NO in the nitrate-containing flue gas. x The liquid ammonia undergoes an SCR denitrification reaction in the SCR denitrification reactor, thereby removing NO from the flue gas. x .
[0012] In some embodiments of this application, the denitrification heat exchanger includes a first denitrification heat exchanger and a second denitrification heat exchanger connected in series, which helps to heat the nitrification-containing flue gas to the required temperature.
[0013] In some embodiments of this application, the liquid ammonia supply unit includes:
[0014] Liquid ammonia storage tank, used for storing liquid ammonia;
[0015] Gas supply unit for providing dry compressed air and / or nitrogen;
[0016] An ammonia-air mixer, connected to the liquid ammonia storage tank and the gas supply unit, is used to mix liquid ammonia with the dry compressed air and / or nitrogen.
[0017] A liquid ammonia metering pump is installed between the liquid ammonia storage tank and the ammonia-air mixer to meter the amount of liquid ammonia delivered to the ammonia-air mixer. This allows for precise supply of the liquid ammonia required for the SCR denitrification reaction, facilitating a smooth reaction process.
[0018] In some embodiments of this application, the SCR denitrification reactor includes at least one layer of denitrification catalyst. This helps to reduce the activation energy required for the SCR denitrification reaction, further improving the reaction rate and efficiency.
[0019] In some embodiments of this application, the denitrification catalyst satisfies at least one of the following conditions:
[0020] The denitrification catalyst has a honeycomb channel structure;
[0021] The carrier of the denitrification catalyst is titanium dioxide;
[0022] The active component of the denitrification catalyst includes a composition of vanadium pentoxide and tungsten trioxide. This helps to further reduce the activation energy required for the SCR denitrification reaction, thereby further improving the reaction rate and efficiency.
[0023] In some embodiments of this application, the SCR denitrification assembly further includes:
[0024] A temperature sensor is installed between the mixer and the SCR denitrification reactor to monitor the temperature of the mixture. This allows the SCR denitrification reaction to be controlled at a specific temperature, contributing to its smooth and efficient operation.
[0025] In some embodiments of this application, the conversion component includes:
[0026] A conversion reactor is used to convert SO2 in the first flue gas into SO3 to obtain a fourth flue gas.
[0027] A heat exchanger is used to cool the fourth flue gas to obtain the second flue gas.
[0028] This helps to significantly reduce the SO2 content in flue gas.
[0029] In some embodiments of this application, the conversion heat exchanger includes a first conversion heat exchanger and a second conversion heat exchanger connected in series, thereby obtaining a cooled second flue gas.
[0030] In some embodiments of this application, at least one of the following is also included:
[0031] A nitrogen oxide detector is installed at the outlet of the SCR denitrification reactor and connected to the SCR denitrification reactor and the liquid ammonia delivery metering pump. It is used to detect the nitrogen oxide content in the first flue gas and adjust the liquid ammonia delivery metering pump according to the nitrogen oxide content in the first flue gas.
[0032] An ammonia concentration detector, positioned between the nitrogen oxide detector and the conversion reactor, is used to detect the degree of ammonia slip in the SCR denitrification component. This facilitates accurate monitoring of the SCR denitrification reaction and further promotes its smooth progress.
[0033] A second aspect of this application proposes a smelting flue gas acid production system, including the aforementioned integrated SCR denitrification and conversion device.
[0034] In some embodiments of this application, the smelting flue gas acid production system further includes: a purification device for washing the smelting flue gas to obtain a first smelting flue gas; a dry absorption device connected to the purification device for removing moisture from the first smelting flue gas to obtain a nitrate-containing flue gas; a first connecting pipeline disposed between the dry absorption device and the SCR denitrification and conversion integrated device for transporting the nitrate-containing flue gas to the SCR denitrification and conversion integrated device for the removal of nitrogen oxides and the conversion of sulfur dioxide to obtain a second flue gas; a second connecting pipeline disposed between the SCR denitrification and conversion integrated device and the dry absorption device for transporting the second flue gas to the dry absorption device for the absorption of sulfur trioxide to obtain finished acid and a second smelting flue gas; and a desulfurization device connected to the dry absorption device for further removing sulfur dioxide from the second smelting flue gas to obtain emission flue gas. Therefore, using this smelting flue gas acid production system to treat smelting flue gas requires low energy consumption and produces a high-quality finished acid. Attached Figure Description
[0035] Figure 1 This is a schematic diagram of an integrated SCR denitrification and conversion process according to an embodiment of this application.
[0036] Figure 2 This is a schematic diagram of the structure of an SCR denitrification component according to an embodiment of this application.
[0037] Figure 3 This is a schematic diagram of the structure of a liquid ammonia supply unit according to an embodiment of this application.
[0038] Figure 4 This is a schematic diagram of the structure of an SCR denitrification component according to an embodiment of this application.
[0039] Figure 5 This is a schematic diagram of the structure of a conversion component according to an embodiment of this application.
[0040] Figure 6 This is a schematic diagram of the structure of an integrated SCR denitrification and conversion device according to an embodiment of this application.
[0041] Figure 7 This is a flowchart of an apparatus for producing acid from smelting flue gas according to an embodiment of this application.
[0042] Figure 8 This is a flowchart of a metallurgical flue gas acid production system in related technologies.
[0043] Figure label:
[0044] 1: Denitrification heat exchanger; 2: Liquid ammonia supply unit; 3: Mixer; 4: SCR denitrification reactor; 5: Liquid ammonia storage tank; 6: Gas supply unit; 7: Ammonia-air mixer; 8: Liquid ammonia delivery metering pump; 9: Temperature detector; 10: Conversion reactor; 11: Conversion heat exchanger; 12: Nitrogen oxides detector; 13: Ammonia concentration detector.
[0045] A: First denitrification heat exchanger B: Second denitrification heat exchanger C1: Denitrification catalyst C2: Denitrification catalyst D: First conversion heat exchanger E: Second conversion heat exchanger Detailed Implementation
[0046] The embodiments of this application are described in detail below. The embodiments described below are exemplary and intended to explain this application, and should not be construed as limiting this application.
[0047] This application is based on the applicant's following findings and insights:
[0048] Currently, industrial flue gas denitrification mainly includes low-temperature denitrification, medium-temperature denitrification, and high-temperature denitrification. High-temperature SCR denitrification (above 450℃) is widely used in power plant denitrification due to its strict requirements on process conditions and catalysts, but it is rarely used in flue gas acid production. Low-temperature denitrification (150℃~300℃) and medium-temperature denitrification (260℃~450℃) have relatively lower requirements on process conditions and catalysts, so they are more commonly used in flue gas acid production. However, when denitrification is carried out in the temperature range of 150℃~400℃, SO3 and SO2 in the process flue gas are very likely to react with nitrogen oxides in the flue gas to form nitrososulfate compounds, which greatly reduces the denitrification effect. Therefore, in related technologies, sulfides in industrial flue gas are removed before denitrification.
[0049] As mentioned earlier, in related technologies, industrial flue gas undergoes desulfurization before denitrification. On one hand, after SO2 in the industrial flue gas is converted, the temperature is gradually reduced to 160℃~300℃ via a heat exchanger. Within this temperature range, side reactions occur, such as the reduction of NO in the industrial flue gas. x It will react with SO2 to form nitrososulfuric acid compounds, which will not only affect the subsequent SO2 conversion efficiency, but also cause severe corrosion to the equipment, resulting in increased costs. On the other hand, the temperature for denitrification using the SCR denitrification device at the downstream end of the conversion component is 260℃~300℃, which not only requires secondary heating, leading to increased energy consumption, but also below 300℃, the SO2 remaining in the nitrate-containing flue gas will preferentially react with NOx in the flue gas and the reducing agent liquid ammonia in the SCR denitrification component, affecting the denitrification effect and corroding the equipment.
[0050] Based on the above research, the inventors discovered that: on the one hand, SCR denitrification components can be used to remove NO from industrial flue gas at 400℃~450℃.x The removal of NO yields NO. x Flue gas with extremely low SO2 content undergoes further SO2 conversion at this temperature, resulting in NO... x The nitrosulosic acid compounds generated by the reaction with SO2 cannot exist stably and will not cause corrosion of the equipment. On the other hand, after the SCR denitrification reaction is completed at 400℃~450℃, the flue gas temperature is just right for SO2 to undergo a conversion reaction. Therefore, there is no need to reheat the flue gas. Moreover, the SO2 conversion reaction is an exothermic reaction, and the released heat can be used for the denitrification reaction through a heat exchanger, which greatly reduces energy consumption.
[0051] In the first aspect of this application, reference is made to Figure 1 This paper proposes an integrated SCR denitrification and conversion device, comprising an SCR denitrification component and a conversion component. The SCR denitrification component removes nitrogen oxides from nitrate-containing flue gas at 400℃~450℃ to obtain a first flue gas. The conversion component, connected to the SCR denitrification component, converts sulfur dioxide in the first flue gas into sulfur trioxide to obtain a second flue gas. Using this integrated SCR denitrification and conversion device to treat nitrate-containing flue gas requires low energy consumption, has no side reactions occurring in the conversion component, and the NOx content in the obtained second flue gas is less than 100 mg / m³. 3 It complies with national standards for NOx emissions. x Content requirements.
[0052] In some embodiments of this application, reference is made to Figure 6 The integrated SCR denitrification and conversion device may further include: a nitrogen oxide detector 12, installed at the outlet of the SCR denitrification component, connected to the SCR denitrification component and the liquid ammonia delivery metering pump 8, used to detect the nitrogen oxide content in the first flue gas and adjust the liquid ammonia delivery metering pump according to the nitrogen oxide content in the first flue gas. This helps to monitor the degree of reaction and the SCR denitrification effect in real time, thereby making timely adjustments to ensure the smooth and efficient progress of the reaction.
[0053] In some embodiments of this application, reference is made to Figure 6 The integrated SCR denitrification and conversion device may further include an ammonia concentration detector 13, positioned between the nitrogen oxide detector 12 and the conversion reactor 10, for detecting the ammonia slip level of the SCR denitrification component. Specifically, the ammonia slip process parameter of the SCR denitrification component is ≤2.5 mg / m³. 3 This helps to accurately monitor the SCR denitrification reaction and further promotes the smooth progress of the SCR denitrification reaction.
[0054] In some embodiments of this application, reference is made to Figure 2The SCR denitrification assembly includes: a denitrification heat exchanger 1, a liquid ammonia supply unit 2, a mixer 3, and an SCR denitrification reactor 4.
[0055] In some embodiments of this application, reference is made to Figure 4 The SCR denitrification assembly may further include a temperature sensor 9, positioned between the mixer 3 and the SCR denitrification reactor 4, for monitoring the temperature of the mixture. This further controls the SCR denitrification reaction to proceed at a specific temperature, contributing to the smooth and efficient execution of the reaction.
[0056] In some embodiments of this application, reference is made to Figure 5 The conversion assembly includes: a conversion reactor 10 for converting SO2 in the first flue gas into SO3 to obtain a fourth flue gas; and a conversion heat exchanger 11 for cooling the fourth flue gas to obtain a second flue gas.
[0057] In some embodiments of this application, the denitrification heat exchanger 1 is used to heat the nitrate-containing flue gas to 400℃~450℃, specifically, it can be 400℃, 405℃, 410℃, 415℃, 420℃, 425℃, 430℃, 435℃, 440℃, 445℃, 450℃, etc., to obtain a third flue gas. Within the above temperature range, it helps to improve the reaction efficiency of the SCR denitrification reaction, with fewer side reactions. It can basically avoid the problems of nitrogen oxides and SO2 in the nitrate-containing flue gas reacting at too low a temperature, affecting the denitrification efficiency, or the problems of excessively high temperatures placing high demands on the equipment.
[0058] In some embodiments of this application, reference is made to Figure 2 Liquid ammonia supply unit 2 is used to supply liquid ammonia, which is used in the removal of NO. x As a reducing agent during the process, it helps the denitrification reaction proceed smoothly.
[0059] In some embodiments of this application, reference is made to Figure 2 Mixer 3, connected to the denitrification heat exchanger and the liquid ammonia supply unit, is used to mix the liquid ammonia and the third flue gas to obtain a mixture. This ensures that the reducing agent and the third flue gas are uniformly mixed before the SCR denitrification reaction, further improving the reaction efficiency.
[0060] In some embodiments of this application, reference is made to Figure 2 SCR denitrification reactor 4, connected to the mixer, is used to remove NO from the mixture. x The first flue gas is obtained after removal. The mixture enters the SCR denitrification reactor, where the SCR denitrification reaction occurs, and NO is removed. xThe removal rate can reach 90%~98%, specifically 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc., thus obtaining products that are essentially free of NO. x The first plume of smoke.
[0061] In some embodiments of this application, reference is made to Figure 2 The aforementioned denitrification heat exchanger includes a first denitrification heat exchanger A and a second denitrification heat exchanger B connected in series. Using two denitrification heat exchangers helps to accelerate the heating rate of the nitrification-containing flue gas.
[0062] In some embodiments of this application, reference is made to Figure 3 The liquid ammonia supply unit 2 includes: a liquid ammonia storage tank 5, a gas supply unit 6, an ammonia-air mixer 7, and a liquid ammonia delivery metering pump 8.
[0063] In some embodiments of this application, the liquid ammonia storage tank 5 is used for storing liquid ammonia. Liquid ammonia from the tanker truck can be transferred to the storage tank using a liquid ammonia unloading pump, which facilitates long-term storage and use of the liquid ammonia. A gas supply unit 6 provides dry compressed air and / or nitrogen. An ammonia-air mixer 7 is connected to the liquid ammonia storage tank 5 and the gas supply unit 6, and is used to mix the liquid ammonia with the dry compressed air and / or nitrogen. A liquid ammonia delivery metering pump 8 is located between the liquid ammonia storage tank and the ammonia-air mixer, and is used to meter the amount of liquid ammonia delivered to the ammonia-air mixer. This helps to accurately control the amount of liquid ammonia used in the reaction, ensuring the smooth progress of the reaction.
[0064] In some embodiments of this application, dry compressed air or nitrogen is used as a carrier in the ammonia-air mixer, and the mass ratio of liquid ammonia to dry compressed air or nitrogen is 1~5:95~99, specifically 1:95, 2:95, 3:95, 4:95, 5:95, 2:96, 2:97, 2:98, 2:99, 3:99, 4:99, 5:99, etc. Within the above range, the liquid ammonia is more evenly dispersed and mixed uniformly with the dry compressed air or nitrogen, which helps to increase the reaction with NO in the SCR denitrification reaction. x The increased contact area further promotes the smooth progress of the reaction, and can basically avoid uneven dispersion caused by too much liquid ammonia or insufficient reaction caused by too little liquid ammonia.
[0065] In some embodiments of this application, the SCR denitrification reactor includes at least one layer of denitrification catalyst, which can effectively reduce the concentration of liquid ammonia and NO. x The activation energy of the reaction accelerates the reaction rate. (Refer to...) Figure 2 In the SCR denitrification reactor, there are two layers of denitrification catalysts C1 and C2, which can further accelerate the reaction rate.
[0066] In some embodiments of this application, the denitrification catalyst has a honeycomb channel structure, which can increase the contact area between the reactants and the denitrification catalyst, thereby accelerating the forward reaction.
[0067] In some embodiments of this application, the carrier of the denitrification catalyst is titanium dioxide. Titanium dioxide can be made into a porous structure with a high specific surface area, which can provide a large number of active sites. At the same time, titanium dioxide is chemically stable and does not easily react with other substances in the denitrification reaction.
[0068] In some embodiments of this application, the active component of the denitrification catalyst includes a composition of vanadium pentoxide and tungsten trioxide, which helps to further reduce the activation energy of the reaction and accelerate the reaction rate.
[0069] Specifically, vanadium pentoxide (V₂O₅) serves as the main active component. V₂O₅ provides highly efficient redox active sites in the denitrification reaction, promoting the adsorption and reaction of NH₃ and NOx. Its surface acidic sites facilitate the adsorption of NH₃ and, through redox cycles (such as V₂O₅), promote the adsorption and reaction of NH₃ and NOx. 5+ V 4+ It promotes the conversion of NOx to N2 and H2O; tungsten trioxide (WO3) acts as a co-catalyst, which enhances the surface acidity of the catalyst, optimizes the adsorption capacity of NH3, and broadens the temperature window of the catalytic reaction.
[0070] In terms of sulfur and water resistance, WO3 can inhibit the oxidation of SO2 and reduce the formation of sulfate, thereby reducing the deactivation of the catalyst caused by sulfur poisoning. In addition, the synergistic effect of WO3 and V2O5 can reduce the negative impact of water vapor on the catalyst activity.
[0071] In terms of thermal stability, V2O5 is prone to deactivation due to sintering under high temperature conditions (such as 400℃~800℃), while WO3 significantly improves the thermal stability of the catalyst by stabilizing the crystal phase structure of the support (such as inhibiting the transformation of anatase TiO2 to rutile) and dispersing the active components.
[0072] In some embodiments of this application, the conversion heat exchanger includes a first conversion heat exchanger D and a second conversion heat exchanger E connected in series, thereby helping to increase the cooling rate of the fourth flue gas.
[0073] In some embodiments of this application, the reaction between liquid ammonia and nitrogen oxides in the third flue gas in the SCR denitrification reactor is as follows:
[0074] 4NH3 + 4NO + O2 → 4N2 + 6H2O
[0075] Specifically, the adjustment relationship between the nitrogen oxide content in the flue gas and the liquid ammonia delivery metering pump is based on the following formula:
[0076] Y = (A × B × 10) -3 ) × C × r, where: A: volume of nitrate-containing gas, in m³ 3 / h, B: NO content in nitrate-containing flue gas, unit is mg / m³ 3 Y: Ammonia usage in g / h; C: Mass stoichiometric coefficients for NH3 and NO; r: The ratio of actual usage to theoretical usage.
[0077] Furthermore, C is 0.567, which is the stoichiometric coefficient of liquid ammonia and NO in the reaction. Specifically, the molar ratio of NH3 to NO in the reaction is 1:1, the relative molecular mass of NH3 is 17, and the relative molecular mass of NO is 30. Therefore, the reactant mass coefficient C = 0.567 = 17 / 30; r is 1.1~1.25, specifically 1.1, 1.15, 1.2, 1.25, etc. Providing excess liquid ammonia helps the reaction proceed in the forward direction and further improves the reaction efficiency.
[0078] Water is generated during the SCR denitrification reaction in the SCR denitrification unit. The amount of water generated is related to the concentration of nitrogen oxides in the nitrate-containing flue gas, as shown in the specific formula:
[0079] Z = (A × B × 10) -3 ) × D × r, where Z: water produced in the reaction, in g / h, A: amount of nitrate-containing gas in m³ 3 / h, B: Nitrogen oxide content in nitrate-containing flue gas (mg / m³) 3 r: the ratio of actual usage to theoretical usage, D: the mass measurement coefficient of NO and H2O.
[0080] Furthermore, D is 0.9, which is the stoichiometric coefficient of NO and H2O in the reaction. Specifically, the molar ratio of NH3 and H2O in the reaction is 2:3. The relative molecular mass of NH3 is 17 and the relative molecular mass of H2O is 18. Therefore, the reactant mass coefficient C = 0.9 = 18 / 30 × 3 / 2; r is 1.1~1.25.
[0081] The generated water will affect the conversion efficiency of sulfur dioxide in the conversion unit. Therefore, the content of nitrogen oxides in the nitrification flue gas needs to be limited in this SCR denitrification and conversion integrated unit, requiring B ≤ 300 mg / m³. 3 .
[0082] A second aspect of this application proposes a smelting flue gas acid production system, including the aforementioned integrated SCR denitrification and conversion device, with reference to... Figure 7The smelting flue gas acid production system further includes: a purification device for washing the smelting flue gas to obtain a first smelting flue gas; a dry absorption device connected to the purification device for removing moisture from the first smelting flue gas to obtain nitrate-containing flue gas; a first connecting pipeline located between the dry absorption device and the SCR denitrification and conversion integrated device for transporting the nitrate-containing flue gas to the SCR denitrification and conversion integrated device for the removal of nitrogen oxides and the conversion of SO2 to SO3 to obtain a second flue gas; a second connecting pipeline located between the SCR denitrification and conversion integrated device and the dry absorption device for transporting the second flue gas to the dry absorption device for the absorption of sulfur trioxide to obtain finished acid and a second smelting flue gas; and a desulfurization device connected to the dry absorption device for further removing sulfur dioxide from the second smelting flue gas to obtain emission flue gas.
[0083] The smelting flue gas acid production system in the relevant technology refers to Figure 8 Upstream smelting flue gas enters a purification unit for washing. The washed and purified flue gas then enters a dry absorption unit to remove moisture. It then enters a conversion unit to convert SO2 to SO3. After conversion, the flue gas returns to the dry absorption unit, where concentrated sulfuric acid is sprayed onto an absorption tower to absorb SO3 and produce finished acid. The flue gas exiting the dry absorption unit then enters a desulfurization unit to further remove SO2. The process flue gas from the desulfurization unit outlet enters a hot blast furnace for heating, raising the temperature to 200-250°C, which is required for low-temperature SCR denitrification. After SCR denitrification, the chimney discharges in compliance with emission standards. Therefore, using a smelting flue gas acid production system in related technologies requires secondary heating, and during the conversion unit, NO in the flue gas... x It reacts with SO2 to form nitrosulosic acid compounds, causing equipment corrosion. Furthermore, during the absorption of SO3 in the dry adsorption unit to obtain the finished acid, NO... x It will affect the quality of the acid.
[0084] Specifically, the following reaction occurs in the conversion unit:
[0085] NO + 1 / 2O2 → NO2
[0086] NO2+ NO→N2O3
[0087] 2NO + 1 / 2O2 → N2O3
[0088] The following reaction occurs in the dry absorption device: N2O3 + 2H2SO4 → 2NOHSO4 + H2O. As a result, the generated nitrososulfuric acid (NOHSO4) remains in the demister of the dry absorption device, causing corrosion of the equipment.
[0089] Compared with the sulfuric acid production system based on smelting flue gas in related technologies, the sulfuric acid production system based on smelting flue gas in this application has the following advantages:
[0090] (1) No nitrososulfuric acid compounds are generated, which will not clog the demister in the dry absorption device, and the quality of the finished acid is improved.
[0091] (2) The temperature of the nitrate-containing flue gas at the inlet of the SCR denitrification and conversion integrated device is 400~450℃, which eliminates the need for secondary heating of the nitrate-containing flue gas, greatly reducing the system energy consumption and operating costs.
[0092] (3) The SCR denitrification and conversion unit are designed in a unified manner, which optimizes the system configuration to the greatest extent.
[0093] A third aspect of this application proposes an integrated SCR denitrification and conversion method, comprising:
[0094] S30: Heat the nitrate-containing flue gas to 400℃~450℃, causing the nitrogen oxides in the nitrate-containing flue gas to undergo an oxidation-reduction reaction, resulting in the first flue gas containing nitrogen and SO2.
[0095] In this step, the nitrogen oxides in the nitrate-containing flue gas undergo a redox reaction by using liquid ammonia as a reducing agent to react with the nitrogen oxides in the nitrate-containing flue gas. The reaction equation is: 4NH3 + 4NO + O2 → 4N2 + 6H2O.
[0096] S40: Convert sulfur dioxide in the first flue gas into sulfur trioxide to obtain a second flue gas containing sulfur trioxide.
[0097] In this step, sulfur dioxide in the first flue gas is converted into sulfur trioxide. Specifically, SO2 and O2 in the flue gas are converted into SO3 gas in the converter under the action of vanadium-based and cesium-based catalysts. The reaction equation is: 2SO2 + O2 → 2SO3.
[0098] In some embodiments of this application, the SCR denitrification conversion integrated method is implemented by the aforementioned SCR denitrification conversion integrated device. Therefore, the SCR denitrification conversion integrated method has all the features and advantages of the aforementioned SCR denitrification conversion integrated device, which will not be repeated here.
[0099] A fourth aspect of this application proposes a method for producing acid from smelting flue gas, comprising:
[0100] S10: The smelting flue gas is scrubbed with dilute sulfuric acid to obtain the first smelting flue gas.
[0101] Specifically, in this step, spraying and washing the smelting flue gas with dilute sulfuric acid helps with the absorption of sulfur trioxide.
[0102] S20: The first smelting flue gas is dried to obtain nitrate-containing flue gas.
[0103] In this step, 93%–95% concentrated sulfuric acid is used to dry the moisture in the first smelting flue gas to 0.1 g / m³. 3 the following.
[0104] S30: Heat the nitrate-containing flue gas to 400℃~450℃, causing the nitrogen oxides in the nitrate-containing flue gas to undergo an oxidation-reduction reaction, resulting in the first flue gas containing nitrogen.
[0105] S40: Convert sulfur dioxide in the first flue gas into sulfur trioxide to obtain a second flue gas containing sulfur trioxide.
[0106] S50: The sulfur trioxide in the second flue gas is removed by spraying concentrated sulfuric acid to obtain the finished acid and the second smelting flue gas.
[0107] In this step, the concentration of concentrated sulfuric acid is 98%. 98% concentrated sulfuric acid has a strong affinity for sulfur trioxide and can react with sulfur trioxide quickly to produce sulfuric acid. Therefore, the absorption of sulfur trioxide is effective and the resulting acid product has high quality.
[0108] S50: Remove sulfur dioxide from the second smelting flue gas to obtain emission flue gas.
[0109] In this step, sulfur dioxide can be removed using hydrogen peroxide, alkaline methods, or calcium methods. Specifically, the hydrogen peroxide method oxidizes SO2 to SO3, which then combines with water to form sulfuric acid. The alkaline method uses NaOH to react SO2 into Na2SO3, and the calcium method uses Ca(OH)2 to react SO2 into Ca2SO3.
[0110] In some embodiments of this application, the method for producing sulfuric acid from smelting flue gas is implemented by the aforementioned smelting flue gas sulfuric acid production system. Therefore, the method for producing sulfuric acid from smelting flue gas has all the features and advantages of the aforementioned smelting flue gas sulfuric acid production system, which will not be repeated here.
[0111] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.
[0112] Example 1
[0113] The smelting flue gas is treated using the smelting flue gas acid production system and method of this application, as follows:
[0114] Flue gas supplied: 100,000 m³ 3 / h, the SO2 volume content in the flue gas is 10% (285714 mg / m³). 3 The nitrogen oxide content in the flue gas was 280 mg / m³. 3 .
[0115] Purification: The smelting flue gas is scrubbed with dilute sulfuric acid to obtain the first smelting flue gas.
[0116] Drying: The first smelting flue gas is dried to obtain a nitrate-containing flue gas with a water content of less than 0.1 g / m³. 3 .
[0117] Integrated SCR denitrification and conversion: The nitrogen-containing flue gas is heated to 400℃~450℃, causing the nitrogen oxides in the flue gas to undergo an oxidation-reduction reaction, resulting in a first flue gas containing nitrogen. This first flue gas enters the conversion module for sulfur dioxide conversion, yielding a second flue gas with a sulfur dioxide content of 85 mg / m³. 3 The nitrogen oxide content is 50 mg / m³ 3 .
[0118] Acid production: Sulfur trioxide in the second flue gas is removed by spraying with 98% concentrated sulfuric acid to obtain finished acid and second smelting flue gas. 99.95% of the sulfur trioxide in the second smelting flue gas is absorbed.
[0119] Desulfurization: Sulfur dioxide in the second smelting flue gas is further removed to obtain nitrogen oxides and sulfur dioxide content in the emission flue gas <100mg / m³. 3 .
[0120] Conclusion: The smelting flue gas sulfuric acid production system and method described in this application, compared with related technologies that first perform desulfurization and then use an SCR denitrification device for denitrification, achieves energy savings of 150 kWh / h and reduces natural gas consumption by 20,000 m³ / h. 3 / sky.
[0121] Test method:
[0122] Sulfur dioxide content in flue gas: spectrophotometry
[0123] Nitrogen oxide content in flue gas: spectrophotometry
[0124] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0125] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. An integrated SCR denitrification and conversion device, characterized in that, include: SCR denitrification unit is used to remove nitrogen oxides from nitrification-containing flue gas at 400℃~450℃ to obtain the first flue gas; A conversion component, connected to the SCR denitrification component, is used to convert sulfur dioxide in the first flue gas into sulfur trioxide to obtain the second flue gas. The SCR denitrification assembly includes: A denitrification heat exchanger is used to heat the nitrate-containing flue gas to obtain a third flue gas; A liquid ammonia supply unit is used to supply liquid ammonia; A mixer, connected to the denitrification heat exchanger and the liquid ammonia supply unit, is used to mix the liquid ammonia and the third flue gas to obtain a mixture. An SCR denitrification reactor, connected to the mixer, is used to remove nitrogen oxides from the mixture to obtain the first flue gas.
2. The integrated SCR denitrification and conversion device according to claim 1, characterized in that, The denitrification heat exchanger includes a first denitrification heat exchanger and a second denitrification heat exchanger connected in series.
3. The integrated SCR denitrification and conversion device according to claim 1, characterized in that, The liquid ammonia supply unit includes: Liquid ammonia storage tank, used for storing liquid ammonia; Gas supply unit for providing dry compressed air and / or nitrogen; An ammonia-air mixer, connected to the liquid ammonia storage tank and the gas supply unit, is used to mix liquid ammonia with the dry compressed air and / or nitrogen. A liquid ammonia delivery metering pump is installed between the liquid ammonia storage tank and the ammonia-air mixer to measure the amount of liquid ammonia delivered to the ammonia-air mixer.
4. The integrated SCR denitrification and conversion device according to claim 1, characterized in that, The SCR denitrification reactor includes at least one layer of denitrification catalyst.
5. The integrated SCR denitrification and conversion device according to claim 4, characterized in that, The denitrification catalyst meets at least one of the following conditions: The denitrification catalyst has a honeycomb channel structure; The carrier of the denitrification catalyst is titanium dioxide; The active component of the denitrification catalyst includes a composition of vanadium pentoxide and tungsten trioxide.
6. The integrated SCR denitrification and conversion device according to claim 1, characterized in that, The SCR denitrification assembly also includes: A temperature detector is installed between the mixer and the SCR denitrification reactor to monitor the temperature of the mixture.
7. The integrated SCR denitrification and conversion device according to claim 3, characterized in that, The conversion component includes: A conversion reactor is used to convert SO2 in the first flue gas into SO3 to obtain a fourth flue gas. A heat exchanger is used to cool the fourth flue gas to obtain the second flue gas.
8. The integrated SCR denitrification and conversion device according to claim 7, characterized in that, The heat exchangers involved in the conversion include a first heat exchanger and a second heat exchanger connected in series.
9. The integrated SCR denitrification and conversion device according to claim 7, characterized in that, It also includes at least one of the following: A nitrogen oxide detector is installed at the outlet of the SCR denitrification reactor and connected to the SCR denitrification reactor and the liquid ammonia delivery metering pump. It is used to detect the nitrogen oxide content in the first flue gas and adjust the liquid ammonia delivery metering pump according to the nitrogen oxide content in the first flue gas. An ammonia concentration detector is installed between the nitrogen oxide detector and the conversion reactor to detect the degree of ammonia slip in the SCR denitrification component.
10. A system for producing acid from smelting flue gas, characterized in that, The SCR denitrification and conversion integrated device includes any one of claims 1 to 9.
11. The smelting flue gas acid production system according to claim 10, characterized in that, The smelting flue gas acid production system also includes: A purification device is used to wash the smelting flue gas to obtain the first smelting flue gas; A dry suction device, connected to the purification device, is used to remove moisture from the first smelting flue gas to obtain nitrate-containing flue gas; The first connecting pipeline is located between the dry suction device and the SCR denitrification and conversion integrated device, and is used to transport the nitrate-containing flue gas to the SCR denitrification and conversion integrated device for the removal of nitrogen oxides and the conversion of sulfur dioxide to obtain the second flue gas; The second connecting pipeline is located between the SCR denitrification and conversion integrated device and the dry absorption device, and is used to transport the second flue gas to the dry absorption device for the absorption of sulfur trioxide to obtain finished acid and second smelting flue gas. A desulfurization device, connected to the dry absorption device, is used to further remove sulfur dioxide from the second smelting flue gas to obtain emission flue gas.