Dry suction device and flue gas acid making system

Abstract

The application relates to the technical field of flue gas purification and chemical engineering, and discloses a dry absorption device and a flue gas acid-making system. The dry absorption device comprises an absorption tower and a denitration assembly connected with the absorption tower. The absorption tower comprises a demisting catcher. The denitration assembly comprises a denitration reactor. The denitration reactor comprises a denitration reactor body. The denitration reactor body is provided with a nitrate sulfuric acid inlet, a sulfur dioxide inlet and a waste gas outlet. A reaction space is defined in the denitration reactor body. The reaction space is used for making a mixture comprising nitrate sulfuric acid and sulfur dioxide to perform a denitration reaction, so as to remove nitrous sulfuric acid in the nitrate sulfuric acid and obtain first sulfuric acid. The mass concentration of sulfuric acid in the mixture is 93% to 98%. A heater is arranged in the denitration reactor body and used for heating the mixture. The dry absorption device can effectively eliminate the problem of the demisting catcher being blocked in the absorption tower. Meanwhile, the quality of finished acid can be greatly improved.

Description

Technical Field

[0001] This application relates to the field of flue gas purification and chemical technology, specifically to a dry absorption device and a flue gas acid production system. Background Technology

[0002] SO2 in industrial flue gas is one of the main causes of serious pollution problems such as acid rain, smog, and photochemical smog. Currently, the most common method for treating industrial flue gas is to use a flue gas sulfuric acid production system, which can convert SO2 in the flue gas into sulfuric acid for sale while ensuring emission standards are met. However, in related technologies, during flue gas sulfuric acid production, nitrogen oxides in the flue gas form nitrosulosic acid in the dry absorption section. This not only causes equipment blockage and increased system resistance, thus increasing energy consumption, but can also lead to system shutdown in severe cases. Furthermore, the nitrosulosic acid formed in the dry absorption section remains in the equipment, significantly affecting the quality of the finished acid. Therefore, developing a dry absorption device and flue gas sulfuric acid production system that can effectively solve the problem of equipment blockage in the dry absorption section is one of the current challenges. Utility Model Content

[0003] This application aims to at least partially solve one of the technical problems in the related art. To this end, one objective of this application is to provide a dry suction device and a flue gas acid production system. Using the dry suction device and flue gas acid production system of this application to treat process flue gas can effectively eliminate equipment corrosion and reduce the required energy consumption to a certain extent. At the same time, by enriching nitrososulfuric acid into the waste acid discharged from the demister and leading it out for environmental protection treatment, the quality of the finished acid is greatly improved.

[0004] A first aspect of this application provides a dry suction device, comprising:

[0005] Including the connected absorption tower and denitrification components:

[0006] An absorption tower, the absorption tower including a demister for collecting nitrososulfuric acid generated inside the absorption tower;

[0007] Denitrification assembly, the denitrification assembly comprising:

[0008] A denitrification reactor, connected to the demister, comprising:

[0009] The denitrification reactor body is provided with a nitrate-containing sulfuric acid inlet, a sulfur dioxide inlet and a waste gas outlet, and the denitrification reactor body internally defines a reaction space;

[0010] The nitrososulfuric acid collected by the demister is transported to the reaction space through the nitrate-containing sulfuric acid inlet, where it is mixed with sulfur dioxide to carry out a denitrification reaction, yielding nitrogen and first sulfuric acid. The mass concentration of sulfuric acid in the mixture in the reaction space is 93% to 98%.

[0011] A heater is installed inside the denitrification reactor body to heat the mixture in the reaction space.

[0012] This dry absorption device innovatively incorporates a denitrification component, which can denitrate the nitrososulfuric acid captured by the demister in the absorption tower to obtain first sulfuric acid free of nitrate impurities. This not only solves the problem of demister blockage caused by the continuous accumulation of nitrososulfuric acid in the dry absorption device, but also the problems of equipment corrosion and impact on the quality of finished acid caused by nitrososulfuric acid.

[0013] In addition, the dry suction device according to the above embodiments of this application may also have the following additional technical features:

[0014] In some embodiments of this application, the absorption tower further includes:

[0015] A waste acid collector, connected to the demister, is used to collect the nitrososulfuric acid;

[0016] The demister drain outlet pipe is connected to the waste acid collector and the denitrification reactor, and is used to transport the nitrososulfuric acid from the nitrate-containing sulfuric acid inlet to the denitrification reactor.

[0017] This allows the nitrate-containing waste acid in the absorption tower to be collected and discharged, preventing long-term accumulation that could clog the demister.

[0018] In some embodiments of this application, the denitrification assembly further includes:

[0019] A denitrification cooler, connected to the denitrification reactor, is used to cool the first sulfuric acid to obtain the second sulfuric acid;

[0020] A sulfur dioxide saturated reactor, connected to the denitrification cooler and the denitrification reactor, is used to dissolve sulfur dioxide in the second sulfuric acid to obtain sulfur dioxide-saturated sulfuric acid. This sulfur dioxide-saturated sulfuric acid is then transported to the denitrification reactor through the sulfur dioxide inlet. This helps to form a closed loop in the denitrification assembly, further improving its stability and controllability.

[0021] In some embodiments of this application, the denitrification assembly includes multiple denitrification reactors connected in series or parallel. This helps improve denitrification efficiency while ensuring the flexibility and reliability of the denitrification assembly operation, and simultaneously meets the requirements of continuous and batch reactions. In some embodiments of this application, the denitrification reactor further includes at least one of the following:

[0022] A stirrer, located inside the denitrification reactor body, is used to stir the mixture;

[0023] A thermometer, connected to the denitrification reactor body, is used to monitor the temperature of the denitrification reaction;

[0024] A level gauge, connected to the denitrification reactor body, is used to monitor the operating level of the denitrification reactor. This helps ensure the smooth and accurate progress of the denitrification reaction.

[0025] In some embodiments of this application, the sulfur dioxide saturated reactor is a Venturi structure.

[0026] In some embodiments of this application, the denitrification assembly further includes:

[0027] A first delivery pump is disposed between the denitrification reactor and the denitrification cooler for delivering the first sulfuric acid to the denitrification cooler;

[0028] A quality acid collection unit, connected to the sulfur dioxide saturated reactor, is used to collect sulfuric acid saturated with sulfur dioxide that meets nitrate standards.

[0029] In some embodiments of this application, the first delivery pump satisfies at least one of the following conditions:

[0030] The first transfer pump includes at least one of a horizontal transfer pump and a vertical submersible transfer pump;

[0031] The first delivery pump outlet is equipped with a liquid level regulating valve, which is interlocked with the liquid level gauge in the denitrification reactor to ensure that the denitrification reactor operates at the normal operating liquid level.

[0032] A second aspect of this application proposes a flue gas acid production system, including the aforementioned dry suction device. Therefore, this flue gas acid production system possesses all the features and advantages of the aforementioned dry suction device, which will not be repeated here. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a dry suction device according to an embodiment of this application.

[0034] Figure 2 This is a flowchart of a flue gas acid production system according to an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1: Absorption Tower 2: Denitrification Component 1-1: Absorption Tower Body 1-2: Demister 1-3: Waste Acid Collector 1-4: Demister Drainage Pipe 1-5: Demister Wetting Spray Mechanism 2-1: Denitrification Reactor 2-2: Denitrification Cooler 2-3: Sulfur Dioxide Saturated Reactor 2-4: First Transfer Pump 2-5: Quality Acid Collection Unit 2-6: First Pipeline 2-1-1: Denitrification Reactor Body ΔP: Demister Differential Pressure Analyzer G1: Demister Wetting Switch Valve A: Nitrate-containing Sulfuric Acid Inlet B: Sulfur Dioxide Inlet C: Waste Gas Outlet F1: Flow Meter T1: Thermometer L1: Level Gauge G2: Level Regulating Valve D: Cooling Return Water Pipeline E: Cooling Supply Water Pipeline T2: Thermometer F2: Flow Meter G3: Reaction Regulating Valve G4: Acid Production Switch Valve C1: Nitrate Analyzer C2: Nitrogen Oxide Analyzer Detailed Implementation

[0037] 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.

[0038] This application is based on the applicant's following findings and insights:

[0039] As mentioned earlier, during flue gas acid production, nitrogen oxides in the process flue gas will form nitrososulfuric acid in the dry absorption section. When nitrososulfuric acid accumulates to a certain amount, it will cause blockage of the demister, resulting in increased resistance in the flue gas acid production system and affecting the smooth progress of the acid production process. At the same time, if the nitrososulfuric acid formed in the dry absorption section is not collected in time, it will mix with the concentrated sulfuric acid sprayed in the absorption tower, leading to accelerated corrosion of equipment and pipelines and reduced service life. In related technologies, the nitrosulosic acid collected in the absorption tower is periodically discharged for treatment. There are three main methods. The first method involves adding a liquid reducing agent to the nitrosulosic acid. Commonly used liquid reducing agents include hydrazine hydrate and hydroxylamine. Taking hydrazine hydrate (N2H4·H2O) as an example, the reaction equation for treating NOHSO4 is: 3N2H4·H2O + 4NOHSO4 → 4H2SO4 + 5N2 + 7H2O. On the one hand, the liquid reducing agent used in this method is expensive, greatly increasing the treatment cost. On the other hand, the amount of liquid reducing agent added needs to be strictly controlled, as these reducing agents are generally carcinogenic, and once released, they will bring new pollution and have a more serious impact. The second method involves adding a small amount of water to the nitrosulosic acid for dilution and hydrolysis. During hydrolysis, NOHSO4 decomposes into NO and NO2, which are released in gaseous form. If NO and NO2 are directly discharged, they will cause new pollution. Therefore, they need to be absorbed by rinsing with dilute nitric acid solution, neutralized, and then discharged, which greatly increases the cost. The third method uses SO2 as a reducing agent, achieving denitrification by introducing a large amount of SO2-containing process gas into nitrosulans. The reaction equation is as follows: 2NOHSO4 + SO2 + 2H2O → 2NO + 3H2SO4. This method releases NO in gaseous form, which would cause pollution if directly emitted. Using dilute nitric acid solution for rinsing and absorption, followed by neutralization before discharge, would significantly increase costs. Therefore, all methods for treating nitrosulans in these related technologies have obvious drawbacks.

[0040] Based on the above research, the inventors discovered that when NOHSO4 in sulfuric acid products is treated with SO2 as a reducing agent, NOHSO4 preferentially reacts with water in nitrosulosic acid, as shown in the reaction equation: NOHSO4 + 2H2O → 2H2SO4 + 2HNO2. The generated HNO2 is unstable and easily decomposes into NO or NO2 gas. However, if SO2 gas is introduced into the sulfuric acid product while providing a strong acidic reaction medium, the strong acid medium will increase the stability of the reaction intermediate product HNO2, allowing it to exist stably without decomposing into NO or NO2 gas. At the same time, the strong acid medium will also enhance the reducing power of SO2, thereby reducing nitrous acid, the intermediate product of NOHSO4 decomposition, to nitrogen gas. Therefore, using this method to treat nitrates will not generate new pollution and is also low in cost.

[0041] In view of this, in the first aspect of this application, a dry suction device is proposed, referring to Figure 1 The device includes an absorption tower 1 and a denitrification component 2 connected together. The absorption tower is used to absorb sulfur trioxide in the process flue gas to obtain high-quality sulfuric acid. However, nitrogen oxides in the process flue gas will form nitrososulfuric acid in the absorption tower. This application innovatively adds a denitrification component to the dry absorption device. The denitrification component connected to the absorption tower is used to denitrify the nitrososulfuric acid collected in the absorption tower to obtain the first sulfuric acid.

[0042] In the embodiments of this application, reference is made to Figure 1 The absorption tower includes an absorption tower body 1-1 and a demister 1-2. The demister 1-2 is located inside the absorption tower body 1-1 and is used to capture nitrososulfuric acid generated in the absorption tower. Specifically, the process flue gas enters the absorption tower for the absorption of sulfur trioxide. The demister is used to capture acid mist in the absorption tower. However, the nitrogen oxides contained in the process flue gas combine with the acid mist to generate nitrososulfuric acid, which is then captured by the demister.

[0043] In the embodiments of this application, reference is made to Figure 1 The absorption tower also includes a waste acid collector 1-3, which is located inside the absorption tower body 1-1, connected to the demister 1-2 and located below the demister. The connection between the demister and the waste acid collector is a hollow design. Since the process flue gas enters the absorption tower from top to bottom, it can enter the demister through the hollow position of the waste acid collector. The demister captures the generated nitrososulfuric acid and then it flows naturally into the waste acid collector, thereby collecting the captured nitrososulfuric acid.

[0044] In the embodiments of this application, reference is made to Figure 1 The absorption tower further includes: a demister drain outlet pipe 1-4, which is located inside the absorption tower body 1-1 and connected to the waste acid collector 1-3, for transporting the nitrososulfuric acid in the waste acid collector to the denitrification component for denitrification treatment.

[0045] In the embodiments of this application, reference is made to Figure 1 The absorption tower also includes a demister wetting spray mechanism 1-5, which is installed inside the absorption tower body 1-1. The demister spray mechanism sprays clean sulfuric acid onto the demister to prevent nitrososulfuric acid from crystallizing and precipitating on the demister, which would cause the crystallized nitrososulfuric acid to clog the demister. Clogged demister would increase local airflow resistance, causing the process flue gas to deviate and resulting in droplet escape.

[0046] In the embodiments of this application, reference is made to Figure 1A differential pressure analyzer ΔP is installed on the outside of the demister 1-2 to monitor the pressure difference between the inlet and outlet of the demister and determine whether the demister is blocked. Specifically, the pressure drop between the inlet and outlet of the demister is maintained between 0 and 1.5 kPa, which can be 0.5 kPa, 1 kPa, 1.5 kPa, etc. When the pressure drop between the inlet and outlet exceeds the above range, it indicates that the demister is blocked.

[0047] In the embodiments of this application, reference is made to Figure 1 The denitrification component 2 includes a denitrification reactor 2-1, which is used for the redox reaction of sulfur dioxide and nitrosulosic acid under certain conditions. The reaction equation is: 4H₂O + 2NOHSO₄ + 3SO₂ → 5H₂SO₄ + N₂, and the products are nitrogen gas and sulfuric acid. This process denitrates the nitrosulosic acid to obtain first sulfuric acid, achieving low-cost and environmentally friendly treatment of nitrosulosic acid.

[0048] In the embodiments of this application, reference is made to Figure 1 The denitrification assembly 2 may further include a denitrification cooler 2-2, connected to the denitrification reactor 2-1, for cooling the first sulfuric acid to obtain a second sulfuric acid. This reduces the corrosion of equipment and pipelines by the second sulfuric acid under high-temperature conditions, thereby extending equipment lifespan.

[0049] In the embodiments of this application, reference is made to Figure 1 The denitrification assembly 2 may further include a sulfur dioxide saturated reactor 2-3, connected to the denitrification nitric acid cooler 2-3 and the denitrification reactor 2-1, for dissolving sulfur dioxide in the second sulfuric acid to obtain sulfur dioxide-saturated sulfuric acid, which is then transported to the denitrification reactor as a reactant. Thus, this denitrification device forms a closed loop by connecting the denitrification reactor 2-1, the denitrification nitric acid cooler 2-2, and the sulfur dioxide saturated reactor 2-3. On one hand, the first sulfuric acid is cooled in the denitrification reactor to obtain the second sulfuric acid. The lower temperature of the sulfuric acid increases its solubility, allowing the second sulfuric acid to absorb more sulfur dioxide in the sulfur dioxide saturated reactor to reach saturation, providing more reducing agent sulfur dioxide for the denitrification reaction and further promoting its rapid progress. On the other hand, the denitrification nitric acid cooler removes heat generated by the exothermic denitrification reaction in the denitrification reactor, preventing excess heat from causing side reactions and ensuring the smooth progress of the denitrification reaction. Therefore, the system stability and controllability of the denitrification assembly can be effectively improved.

[0050] In some embodiments of this application, reference is made to Figure 1The denitrification assembly 2 further includes a first delivery pump 2-4, which is disposed between the denitrification reactor 2-1 and the denitrification cooler 2-2, for delivering the first sulfuric acid to the denitrification cooler. This helps to increase the transmission speed of the first sulfuric acid to the denitrification cooler and shorten the transmission time, thereby meeting the requirements of large-scale industrial denitrification treatment of sulfuric acid containing nitrates.

[0051] In some embodiments of this application, reference is made to Figure 1 The denitrification assembly 2 further includes a quality acid collection unit 2-5, which is connected to the sulfur dioxide saturated reactor 2-3 and is used to collect sulfuric acid saturated with sulfur dioxide that meets the nitrate standard to obtain a high-quality sulfuric acid product.

[0052] In some embodiments of this application, reference is made to Figure 1 The denitrification assembly 2 further includes: a first pipeline 2-6, which is connected to the first delivery pump 2-4 and the demister wetting spray mechanism 1-5, for delivering the first sulfuric acid delivered by the first delivery pump to the demister wetting spray mechanism, and for spraying the first sulfuric acid onto the demister to prevent the crystallization and precipitation of nitrososulfuric acid on the demister.

[0053] In some embodiments of this application, reference is made to Figure 1 The first pipeline 2-6 is also equipped with a demister wetting switch valve G1, which is interlocked with the differential pressure analyzer ΔP on the absorption tower body. When the differential pressure value at the inlet and outlet of the demister increases, the demister wetting switch valve G1 can be opened to spray the first sulfuric acid. The spraying time is 3 min to 5 min, which can be adjusted according to the differential pressure value at the inlet and outlet of the demister.

[0054] In some embodiments of this application, the denitrification assembly may include multiple denitrification reactors, which may be connected in series or in parallel. Using multiple denitrification reactors helps improve denitrification efficiency while ensuring the flexibility and reliability of the denitrification device operation.

[0055] In some embodiments of this application, reference is made to Figure 1 The denitrification reactor 2-1 includes a denitrification reactor body 2-1-1, which is provided with a nitrate-containing sulfuric acid inlet A, a sulfur dioxide inlet B, and a waste gas outlet C. A flow meter F1 is installed at the nitrate-containing sulfuric acid inlet A to monitor the volumetric flow rate of the nitrate-containing sulfuric acid. The denitrification reactor body defines a reaction space for carrying out a denitrification reaction on a mixture including nitrate-containing sulfuric acid and sulfur dioxide to remove nitrosylsulfuric acid from the nitrate-containing sulfuric acid to obtain first sulfuric acid. The specific reaction equation for the denitrification reaction is as follows:

[0056] 2NOHSO4 + 2H2O → 2H2SO4 + 2HNO2

[0057] 3SO2 + 3H2O → 3H2SO3

[0058] 2HNO2 + 3H2SO3 → 3H2SO4 + N2 + H2O

[0059] The intermediate product HNO2 easily decomposes into NO or NO2 gas, requiring a strong acid medium to prevent its decomposition. Therefore, the mass concentration of the mixture is required to be 93%–98%, specifically 93%, 94%, 95%, 96%, 97%, 98%, etc. The mixture includes sulfuric acid saturated with nitrosulanium and sulfur dioxide. This concentration range improves the stability of the intermediate product HNO2, preventing its decomposition into NO or NO2 gas. It also enhances the reducing power of sulfur dioxide, allowing it to undergo a redox reaction with nitrosulanium to produce nitrogen and sulfuric acid. Thus, this concentration range effectively avoids the problems of high cost and waste of high-quality sulfuric acid due to excessively high sulfuric acid concentration, as well as the problems of easily decomposing HNO2 into NO or NO2 gas and reduced sulfur dioxide reducing power due to excessively low sulfuric acid concentration.

[0060] In some embodiments of this application, the structure of the denitrification reactor body can be any one of the following: trough structure, tubular structure, or kettle structure. This helps to make it applicable to different fields and different processes, and at the same time, the structure of the denitrification reactor body can be flexibly designed according to the site and other factors.

[0061] In the embodiments of this application, the demisting collector 1-2 can be a standing fiber demisting collector. The standing design of the demisting collector helps to intercept mist droplets and has a small footprint. Since the flue gas flows from bottom to top, the standing demisting collector is in the same direction as the flue gas flow, which can improve the collection efficiency of nitrososulfuric acid. The fiber material is corrosion resistant and has a large specific surface area, which can further improve the collection efficiency of nitrososulfuric acid while ensuring that the equipment is not easily corroded.

[0062] In some embodiments of this application, a heater is provided inside the denitrification reactor body to heat the mixture. When the heat of the denitrification reaction is insufficient or when the system is restarted, the heater can supplement the heat to meet the heat required for the denitrification reaction and ensure the smooth operation of the denitrification reactor. Specifically, the heater can be electrically heated or steam heated, and the heating coil is made of high-temperature resistant and concentrated acid resistant alloy material or equivalent material.

[0063] In some embodiments of this application, the denitrification reactor body is provided with a stirrer for stirring the mixture, which helps to mix the nitrate-containing sulfuric acid and sulfur dioxide-saturated sulfuric acid evenly, so that the denitrification reaction can proceed more fully.

[0064] In some embodiments of this application, reference is made to Figure 1 The denitrification reactor also includes a thermometer T1, which is connected to the denitrification reactor body 2-1-1 and is used to monitor the temperature of the denitrification reaction to ensure that the denitrification reaction proceeds smoothly.

[0065] Specifically, the denitrification reaction temperature is 60℃~90℃, preferably 70℃~80℃, and can be 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, etc. Within the above temperature range, the denitrification reaction can proceed smoothly and efficiently, and can basically avoid problems such as high equipment requirements due to excessively high temperature, and incomplete reaction due to excessively low temperature. The reaction pressure is atmospheric pressure. In some embodiments of this application, the above denitrification reaction time is 0.3h~0.7h, specifically 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, etc. The above reaction time can help the denitrification reaction to proceed fully, and can basically avoid incomplete reaction due to too short reaction time, and wasted time cost due to too long reaction time.

[0066] In some embodiments of this application, reference is made to Figure 1 The denitrification reactor also includes a level gauge L1, which is connected to the denitrification reactor body 2-1-1 and is used to monitor the operating level of the denitrification reactor. This allows for precise control of the denitrification reaction level and promotes efficient and stable reaction.

[0067] In some embodiments of this application, reference is made to Figure 1 A nitrogen oxide analyzer C2 is installed at the exhaust gas outlet C of the denitrification reactor body to monitor the nitrogen oxide content in the exhaust gas discharged from the denitrification reactor body, thereby determining whether the denitrification reaction is proceeding normally. Specifically, if the nitrogen oxide content in the exhaust gas monitored by the nitrogen oxide analyzer is ≤10mg / Nm3, it indicates that the reaction is proceeding normally.

[0068] In some embodiments of this application, reference is made to Figure 1 The outlet of the first delivery pump 2-4 is equipped with a liquid level regulating valve G2, which is interlocked with the liquid level gauge L1 in the denitrification reactor. This valve is used to control the operating liquid level in the denitrification reactor, which can prevent leakage caused by excessively high denitrification reaction liquid level and insufficient denitrification reaction caused by excessively low liquid level.

[0069] Specifically, the level regulating valve G2 is interlocked with the level gauge L1. When the level gauge shows a low level in the denitrification reactor, the level regulating valve can be adjusted to reduce the discharge rate of the first sulfuric acid in the denitrification reactor; when the level gauge shows a high level, the level regulating valve can be adjusted to increase the discharge rate of the first sulfuric acid in the denitrification reactor. This helps to control the smooth progress of the denitrification reaction and further ensures the normal operation of the entire closed loop.

[0070] In some embodiments of this application, the first transfer pump can be either a horizontal transfer pump or a vertical submersible transfer pump. This allows for adaptation to different fields and processes, and also enables flexible design of the denitrification reactor structure based on site conditions.

[0071] In some embodiments of this application, the structure of the denitrification cooler can be any of the following: shell-and-tube type, plate type, or other equipment structure that meets the heat exchange requirements. Therefore, it can be adapted to different fields and different processes, and the structure of the denitrification reactor body can be flexibly designed according to site conditions.

[0072] In some embodiments of this application, the denitrification cooler is made of high-temperature and concentrated acid resistant alloy material to prevent the equipment from being corroded.

[0073] In some embodiments of this application, the denitric acid cooler is provided with a cooling return water pipeline D and a cooling supply water pipeline E, thereby ensuring the smooth operation of the denitric acid cooler. The temperature difference between the water in the cooling return water pipeline and the cooling supply water pipeline is between 8°C and 15°C, specifically 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, etc. When the temperature difference is within the above range, the temperature of the second sulfuric acid obtained from the denitric acid cooler basically meets the requirements.

[0074] In some embodiments of this application, reference is made to Figure 1 A thermometer T2 is installed at the outlet of the denitrification cooler 2-2 to monitor the temperature of the second sulfuric acid. The temperature of the second sulfuric acid can be controlled by adjusting the temperature difference between the cooling return water and the cooling supply water.

[0075] Specifically, the temperature of the second sulfuric acid is 40℃~60℃, specifically 40℃, 45℃, 50℃, 55℃, 60℃, etc. The temperature of the second sulfuric acid within the above range helps to improve the solubility of sulfur dioxide in the second sulfuric acid. It can basically avoid the problem that the amount of dissolved sulfur dioxide is too small due to the temperature of the second sulfuric acid being too high, which is insufficient to provide the sulfur dioxide required for the denitrification reaction, as well as the problem that the viscosity of sulfuric acid is too high due to the temperature of the second sulfuric acid being too low, which affects the denitrification reaction and increases energy consumption.

[0076] In some embodiments of this application, the sulfur dioxide saturated reactor 2-3 has a Venturi structure. The nitrososulfuric acid captured by the demister is collected in a waste acid collector with a mass concentration of up to 70% or more. However, the total amount of nitrososulfuric acid collected by the waste acid collector is relatively small, generally 2m³. 3 / d~5m 3 / d, using a Venturi-type sulfur dioxide reactor can significantly save space and investment, while also achieving the highest gas-liquid mass transfer efficiency.

[0077] In some embodiments of this application, reference is made to Figure 1 A flow meter F2 and a reaction regulating valve G3 are installed between the sulfur dioxide saturated reactor 2-3 and the denitrification reactor 2-1. The flow meter F2 is used to monitor the volumetric flow rate of sulfur dioxide saturated sulfuric acid delivered to the denitrification reactor by the saturated sulfuric acid transfer pump. The flow meter F2 is interlocked with the flow meter F1. The ratio between the flow meter F1 and the flow meter F2 is controlled by adjusting the reaction regulating valve G3, thereby ensuring the smooth progress of the denitrification reaction.

[0078] Specifically, the ratio of flow meter F1 to flow meter F2 is 1:15 to 1:25, and can be 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, etc. When the ratio of flow meter F1 to flow meter F2 is too high, it indicates that too much nitrate-containing sulfuric acid is being input into the denitrification reactor. In this case, the amount of sulfur dioxide-saturated sulfuric acid output from the second delivery pump needs to be increased by adjusting the reaction regulating valve 4-4, so that the ratio of flow meter F1 to flow meter F2 is reduced to the above range. Conversely, when the ratio of flow meter F1 to flow meter F2 is too low, it indicates that too much sulfur dioxide-saturated sulfuric acid is being output from the second delivery pump into the denitrification reactor. In this case, the amount of sulfur dioxide-saturated sulfuric acid output from the second delivery pump needs to be reduced by adjusting the reaction regulating valve G3, so that the ratio of flow meter F1 to flow meter F2 is reduced to the above range. This helps the denitrification reaction proceed smoothly.

[0079] In some embodiments of this application, reference is made to Figure 1 The quality acid collection unit 2-5 is connected to the acid production switch valve G4 and the nitrate analyzer C1 at its inlet. The nitrate analyzer monitors the nitrate concentration in sulfur dioxide-saturated sulfuric acid. Once the nitrate concentration in the sulfur dioxide-saturated sulfuric acid meets the standard, the acid production switch valve is opened to deliver the qualified sulfur dioxide-saturated sulfuric acid to the quality acid collection unit, thus obtaining high-quality sulfuric acid product. Specifically, the nitrate concentration in the sulfur dioxide-saturated sulfuric acid is ≤10 mg / m³. 3 It can then be collected as a high-quality sulfuric acid product.

[0080] In some embodiments of this application, the volume of the denitrification reactor body can be calculated with reference to the following formula: V = Q1 × t / K. Wherein, Q1 is the volumetric flow rate (m³) of sulfuric acid saturated with sulfur dioxide supplied by the sulfur dioxide saturated reactor to the denitrification reactor. 3 / h); t is the residence time of the denitrification reaction (h); K is the volume coefficient of the denitrification reactor, K = 0.7~0.8, specifically, it can be 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, etc., which helps the denitrification reaction to proceed fully and ensures that the substances in the reaction system are mixed evenly; V is the volume of the denitrification reactor (m³). 3 ).

[0081] In a second aspect of this application, a flue gas acidification system is provided, including the aforementioned dry absorption device, as described above. Figure 2 The flue gas acidification system also includes a purification device for washing the flue gas to obtain a first flue gas; a drying device for removing moisture from the first flue gas to obtain a second flue gas; and a conversion component connected to the drying device for converting sulfur dioxide in the second flue gas into sulfur trioxide to obtain process flue gas containing sulfur trioxide. The dry absorption device of this application is used to treat the above-mentioned process flue gas.

[0082] Specifically, in the flue gas sulfuric acid production system, the high-quality sulfuric acid collected by the quality acid collection unit can be used in the drying unit, and the high-quality sulfuric acid is transported to the drying tower circulation pump tank as an acid concentration adjustment acid.

[0083] In some embodiments of this application, the exhaust gas from the denitrification reactor outlet of the dry absorption device can be collected with the gas in the sulfur dioxide saturated reactor and then re-enter the flue gas to produce sulfuric acid. This can further ensure that SO2 can be fully utilized to convert into sulfuric acid without any sulfur loss.

[0084] This flue gas acid production system has all the features and advantages of the aforementioned dry absorption device, which will not be repeated here.

[0085] 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.

[0086] Example 1

[0087] The flue gas is treated using the flue gas acidification system of this application, as follows:

[0088] The nitrate impurity content in the nitrosulosic acid collected by the waste acid collector in the absorption tower is 200,000 mg / m³. 3The nitrite impurity content in the sulfur dioxide-saturated sulfuric acid collected from the quality acid collection unit was 3.5 mg / m³. 3 The nitrogen oxide content in the exhaust gas emitted from the denitrification reactor is 5 mg / Nm³. 3 .

[0089] Conclusion: Using the flue gas acid production system of this application to treat flue gas can effectively solve the problem of demister clogging, and at the same time, nitrososulfuric acid can be denitrated and recycled in the dry absorption device.

[0090] Test method:

[0091] Nitrate impurity content: Ultraviolet spectrophotometry / Ion chromatography

[0092] 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.

[0093] 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. A dry suction device, characterized in that, Including the connected absorption tower and denitrification components: An absorption tower, the absorption tower including a demister for collecting nitrososulfuric acid generated inside the absorption tower; Denitrification assembly, the denitrification assembly comprising: A denitrification reactor, connected to the demister, comprising: The denitrification reactor body is provided with a nitrate-containing sulfuric acid inlet, a sulfur dioxide inlet and a waste gas outlet, and the denitrification reactor body internally defines a reaction space; The nitrososulfuric acid collected by the demister is transported to the reaction space through the nitrate-containing sulfuric acid inlet, where it is mixed with sulfur dioxide to carry out a denitrification reaction, yielding nitrogen and first sulfuric acid. The mass concentration of sulfuric acid in the mixture in the reaction space is 93% to 98%. A heater is installed inside the denitrification reactor body to heat the mixture in the reaction space.

2. The dry suction device according to claim 1, characterized in that, The absorption tower also includes: A waste acid collector, connected to the demister, is used to collect the nitrososulfuric acid; The demister drain outlet pipe is connected to the waste acid collector and the denitrification reactor, and is used to transport the nitrososulfuric acid from the nitrate-containing sulfuric acid inlet to the denitrification reactor.

3. The dry suction device according to claim 1, characterized in that, The denitrification assembly also includes: A denitrification cooler, connected to the denitrification reactor, is used to cool the first sulfuric acid to obtain the second sulfuric acid; The sulfur dioxide saturated reactor is connected to the denitrification cooler and the denitrification reactor. It is used to dissolve sulfur dioxide in the second sulfuric acid to obtain sulfur dioxide saturated sulfuric acid. The sulfur dioxide saturated sulfuric acid is transported to the denitrification reactor through the sulfur dioxide inlet.

4. The dry suction device according to claim 1, characterized in that, It includes multiple denitrification reactors, which are connected in series or in parallel.

5. The dry suction device according to claim 1, characterized in that, The denitrification reactor further includes at least one of the following: A stirrer, located inside the denitrification reactor body, is used to stir the mixture; A thermometer, connected to the denitrification reactor body, is used to monitor the temperature of the denitrification reaction; A level gauge is connected to the denitrification reactor body and is used to monitor the operating level of the denitrification reactor.

6. The dry suction device according to claim 3, characterized in that, The sulfur dioxide saturated reactor has a Venturi structure.

7. The dry suction device according to claim 3, characterized in that, The denitrification assembly also includes: A first delivery pump is disposed between the denitrification reactor and the denitrification cooler for delivering the first sulfuric acid to the denitrification cooler; A quality acid collection unit, connected to the sulfur dioxide saturated reactor, is used to collect sulfuric acid saturated with sulfur dioxide that meets nitrate standards.

8. The dry suction device according to claim 7, characterized in that, The first delivery pump satisfies at least one of the following conditions: The first transfer pump includes at least one of a horizontal transfer pump and a vertical submersible transfer pump; The first delivery pump outlet is equipped with a liquid level regulating valve, which is interlocked with the liquid level gauge in the denitrification reactor to ensure that the denitrification reactor operates at the normal operating liquid level.

9. A flue gas acid production system, characterized in that, The dry suction device includes any one of claims 1 to 8.

Images