Cascade washing device for tail gas in AHF production

Abstract

The utility model discloses an AHF production tail gas cascade washing device which is characterized in that a hydrogen fluoride production device is connected with a first tail washing tower through a tail gas pipe, and the first tail washing tower is connected with a second tail washing tower; the first tail washing tower is circularly connected with a circulating water pipe through a first circulating pump; and the second tail washing tower is circularly connected with the circulating water pipe through a second circulating pump. According to the device, stepped washing of the AHF production tail gas is realized, and iodine contained in the tail gas is eluted and separated, so that the problem that the tail gas is red is solved, and the influence on the environment is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of exhaust gas treatment technology, specifically relating to a cascade scrubbing device for AHF production exhaust gas. Background Technology

[0002] Hydrogen fluoride is the foundation of modern fluorine chemical industry, serving as the most basic raw material for the production of elemental fluorine, various fluorinated refrigerants, fluorine-containing new materials, inorganic fluoride salts, and various organic fluorides. Hydrogen fluoride (HF) is extremely reactive, reacting with alkalis, metals, oxides, and silicates. Its aqueous solution is hydrofluoric acid. Industrial hydrofluoric acid is a colorless, clear aqueous solution containing less than 60% hydrogen fluoride. It is transparent, readily volatilizes in open containers, has a strong, pungent odor, and is highly corrosive, rapidly corroding silicon-containing materials such as glass. It exhibits the general properties of acids and is extremely toxic. Hydrogen fluoride gas is highly corrosive to the mucous membranes of the eyes, ears, nose, and throat, and severely corrodes human teeth and bones, causing them to calcify.

[0003] Currently, hydrogen fluoride is prepared using two main methods: the fluorite method and the fluorosilicic acid method. The fluorosilicic acid method primarily utilizes fluorosilicic acid, a byproduct of wet-process phosphoric acid production, to produce hydrogen fluoride. This method boasts high resource utilization, low cost, and can yield high-purity hydrogen fluoride with a mass fraction of up to 98 wt%. The wet-process phosphoric acid method involves reacting phosphate rock with other substances. This process introduces impurities from the phosphate rock into the wet-process phosphoric acid and its byproduct, fluorosilicic acid, such as associated iodine resources, severely impacting the final product quality. Therefore, a deiodization process is necessary. In the raw material fluorosilicic acid supply, the iodide ion content (mainly in the form of hydrogen iodide) is 15-25 ppm. Approximately 2 tons of iodine are introduced into the hydrogen fluoride system each year. Due to the process characteristics of the production system, the inflow and outflow of iodide ions are unbalanced, leading to continuous circulation and concentration within the system. When the iodine content reaches above 120 ppm, the solution turns red. When iodine escapes from the solution, it causes red fumes in the exhaust gas, seriously affecting safety and causing environmental pollution.

[0004] Chinese patent CN112028284A discloses a device and method for removing iodine from acidic wastewater in a tail washing system. The device includes an inlet pipe, one end of which is connected to a raw material tank via a water pump, and the other end of which is connected to symmetrical diversion pipes. Its beneficial effects are that by adding a ceramic membrane, it can prevent equipment blockage and damage caused by iodine enrichment in the supply chain system, reduce tail washing pressure, significantly reduce caustic soda and external water consumption, improve system water balance, reduce the environmental risk of red smoke from tail gas, improve the quality of silicon slag and products, and provide raw material security for the development of downstream new projects.

[0005] Wei Jianying et al. used copper sulfate as a precipitant, sodium thiosulfate as a reducing agent, and hexadecyltrimethylammonium bromide as a coagulant to rapidly precipitate and separate iodine from iodine-containing wastewater. After separating the obtained cuprous iodide precipitate, ferric chloride was used as an oxidant for oxidation, and the iodine was then sublimated to separate it. This method has advantages such as simple operation, large wastewater treatment capacity, fast recovery speed, low cost of reagents, non-toxicity, no harmful substances generated during the recovery process, and an iodine recovery rate of over 96%. (Wei Jianying, Xu Yanmei, Han Zhouxiang, et al. Recovery of iodine from iodine-containing wastewater [J]. Inorganic Salt Industry, 2007, 039(009):47-49.)

[0006] However, in the production process of anhydrous hydrogen fluoride, adding sodium hydroxide and sodium thiosulfate to the tail gas scrubbing tower can alleviate the problem of excessive iodine in the tail gas and causing it to turn red. However, it also traps iodine in the tail scrubbing liquid. When the pH of the tail scrubbing liquid changes to neutral or acidic, a large amount of iodine will be released, making it more difficult to control. Moreover, the released iodine seriously affects the production environment and poses a safety risk to the personnel on duty.

[0007] The residual iodine in fluorosilicic acid can also be introduced into the production process of hydrogen fluoride, causing the problem of excessive iodine content. When the excessive iodine content escapes, it will cause red smoke in the exhaust gas. Direct emission will cause serious environmental problems. Summary of the Invention

[0008] To address the aforementioned technical problems, this utility model provides a stepped scrubbing device for AHF production tail gas, which realizes stepped scrubbing of AHF production tail gas and simultaneously washes away and separates the iodine contained in the tail gas, solving the problem of the tail gas emitting red light and reducing the impact on the environment.

[0009] To achieve the above objectives, this utility model provides a staged scrubbing device for AHF production tail gas. The hydrogen fluoride production device is connected to a first tail gas scrubbing tower via a tail gas pipe, and the first tail gas scrubbing tower is connected to a second tail gas scrubbing tower. The first tail gas scrubbing tower is circulated via a first circulating pump and a circulating water pipe. The second tail gas scrubbing tower is circulated via a second circulating pump and a circulating water pipe.

[0010] Preferably, the first tail washing tower is connected to the circulating water tower via a first circulating pump and a first circulating water valve, and the circulating water tower is connected to the second tail washing tower via a second circulating water valve.

[0011] Preferably, the circulating water tower is connected to the cooling water tower.

[0012] Preferably, the first tail washing tower is connected to the sewage tank via a first vent valve; the second tail washing tower is connected to the sewage tank via a second vent valve.

[0013] Preferably, the exhaust pipe is equipped with a check valve.

[0014] Preferably, one end of the tail gas pipe is connected to the hydrogen fluoride production device, and the other end is connected to the tail gas coil, which is installed inside the first tail gas scrubbing tower.

[0015] More preferably, the exhaust coil is provided with aeration holes.

[0016] Preferably, one end of the circulating water pipe is connected to the circulating pump, and the other end is connected to the circulating water coil.

[0017] More preferably, the circulating water coil is equipped with a sprayer.

[0018] Preferably, the top of the second tail washing tower is equipped with a gas discharge port and a gas detector.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. The water in the two tail gas scrubbing towers absorbs the iodine in the tail gas, reducing the iodine content in the tail gas. At the same time, the aeration holes on the tail gas coil and the sprayers on the circulating water coil ensure that the tail gas and circulating water are evenly distributed in the tail gas scrubbing tower, increasing the contact area between the tail gas and circulating water, improving the iodine removal effect, and dissolving as much iodine as possible into the water to form iodine-containing tail gas scrubbing water and clean tail gas.

[0021] 2. By replenishing circulating water into the second tail gas scrubbing tower, the iodine content in the tail gas scrubbing water in the second tail gas scrubbing tower is maintained at a low level, thereby maintaining a significant concentration difference with the first tail gas scrubbing tower, realizing staged scrubbing of the tail gas, further reducing the iodine content in the tail gas, avoiding red fog at the tail gas emission outlet, and reducing environmental pollution.

[0022] 3. The iodine-containing tail wash water in the tail wash tower is replaced by a circulating water tower, and the circulating water tower is cooled by a cooling water tower equipped with a cooling fan to carry the iodine out of the tail wash device, thereby separating the iodine from the tail gas and preventing the iodine from accumulating in the tail wash device and causing the risk of leakage. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0024] Figure 2 This is a schematic diagram of the exhaust coil structure.

[0025] Figure 3 This is a schematic diagram of the circulating water coil.

[0026] In the diagram, 1 is the hydrogen fluoride production unit, 2 is the first tail washing tower, 3 is the second tail washing tower, 4 is the circulating water tower, 5 is the sewage tank, 6 is the first circulating pump, 7 is the second circulating pump, 8 is the first circulating water valve, 9 is the second circulating water valve, 10 is the first vent valve, 11 is the second vent valve, 12 is the gas detector, 13 is the check valve, 14 is the gas discharge port, 15 is the tail gas pipe, 16 is the circulating water pipe, 17 is the tail gas coil, 18 is the aeration hole, 19 is the sprayer, 20 is the circulating water coil, and 21 is the cooling tower. Detailed Implementation

[0027] The technical solution of this utility model will be further explained below with reference to the accompanying drawings and specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of this utility model and should not be construed as limiting this utility model. The protection scope of this utility model should be determined by the content of the claims. Modifications or substitutions made by those skilled in the art to the technical solution of this utility model without creative effort all fall within the protection scope of this utility model.

[0028] Example 1

[0029] like Figure 1-3 As shown, an AHF production tail gas cascade scrubbing device is provided. The hydrogen fluoride production unit 1 is connected to a first tail gas scrubbing tower 2 via a tail gas pipe 15. The first tail gas scrubbing tower 2 is connected to a second tail gas scrubbing tower 3. The hydrogen fluoride production tail gas is introduced into the first tail gas scrubbing tower 2 and the second tail gas scrubbing tower 3 for gradient scrubbing, separating iodine from the tail gas. The iodine enters the tail gas scrubbing water, while the tail gas is discharged through the second tail gas scrubbing tower 3. The lower part of the first tail gas scrubbing tower 2 is circulatedly connected to the upper part of the second tail gas scrubbing tower 2 via a first circulating pump 6 and a circulating water pipe 16, pumping the tail gas scrubbing water from the bottom of the first tail gas scrubbing tower 2 into the upper part of the first tail gas scrubbing tower 2, thus achieving the recycling of the tail gas scrubbing water. The lower part of the second tail gas scrubbing tower 3 is circulatedly connected to the upper part of the second tail gas scrubbing tower 3 via a second circulating pump 7 and a circulating water pipe 16, pumping the tail gas scrubbing water from the bottom of the second tail gas scrubbing tower 3 into the upper part of the second tail gas scrubbing tower 3, thus achieving the recycling of the tail gas scrubbing water.

[0030] Preferably, the first tail washing tower 2 is connected to the circulating water tower 4 via the first circulating pump 6 and the first circulating water valve 8 to discharge excess tail washing water from the first tail washing tower 2; the circulating water tower 4 is connected to the second tail washing tower 3 via the second circulating water valve 9 to continuously replenish water to the second circulating tower 3 at a fixed amount, so that the iodine concentration in the tail washing water in the second tail washing tower 3 is kept at a low level, forming a significant concentration gradient with the first tail washing tower 2.

[0031] Preferably, the circulating water tower 4 is connected to the cooling water tower 21, and the iodine-containing tail wash water enriched in the circulating water tower 4 is introduced into the cooling water tower 21 for cooling, and the iodine is carried out of the device.

[0032] Preferably, the first tail washing tower 2 is connected to the sewage tank 5 via the first vent valve 10, and the tail washing water is periodically discharged from the device; the second tail washing tower 3 is connected to the sewage tank 5 via the second vent valve 11, and the tail washing water is periodically discharged from the device.

[0033] Preferably, the exhaust pipe 15 is provided with a check valve 13 to prevent exhaust gas from flowing back.

[0034] Preferably, one end of the tail gas pipe 15 is connected to the hydrogen fluoride production device 1, and the other end is connected to the tail gas coil 17. The tail gas coil 17 is installed inside the first tail washing tower 2. The tail gas generated by the hydrogen fluoride production device 1 is sent into the lower part of the first tail washing tower 2 through the tail gas coil 17 to perform countercurrent washing with the tail washing water, thereby improving the washing effect.

[0035] In a further preferred embodiment, the exhaust gas coil 17 is provided with aeration holes 18, which can release the exhaust gas evenly, increase the contact area with the tail wash water, and further enhance the washing effect.

[0036] Preferably, one end of the circulating water pipe 16 is connected to the circulating pump, and the other end is connected to the circulating water coil 20.

[0037] More preferably, the circulating water coil 20 is equipped with a sprayer 19, which can evenly distribute the tail wash water in the tail wash tower, increase the contact area between the tail wash water and the tail gas, and improve the washing effect.

[0038] Preferably, the second tail scrubbing tower 3 is provided with a gas discharge port 14 and a gas detector 12 at the top. The gas discharge port 14 can discharge the tail gas, and the gas detector 12 can detect the composition and content of the tail gas at the top of the tail scrubbing tower and monitor the tail gas emission in real time.

[0039] Preferably, an overflow pipe is provided between the second tail washing tower 3 and the first tail washing tower 2, which can overflow excess liquid in the second tail washing tower 3 into the first tail washing tower 3 to avoid affecting the washing effect of the second tail washing tower 3, and at the same time, can replenish the liquid in the first tail washing tower 3.

Claims

1. A staged scrubbing device for AHF production exhaust gas, characterized in that: The hydrogen fluoride production unit (1) is connected to the first tail washing tower (2) via the tail gas pipe (15), and the first tail washing tower (2) is connected to the second tail washing tower (3); the first tail washing tower (2) is circulated via the first circulating pump (6) and the circulating water pipe (16); the second tail washing tower (3) is circulated via the second circulating pump (7) and the circulating water pipe (16).

2. The AHF production tail gas stage scrubbing device according to claim 1, characterized in that: The first tail washing tower (2) is connected to the circulating water tower (4) via the first circulating pump (6) and the first circulating water valve (8), and the circulating water tower (4) is connected to the second tail washing tower (3) via the second circulating water valve (9).

3. The AHF production tail gas staged scrubbing device according to claim 2, characterized in that: The circulating water tower (4) is connected to the cooling water tower (21).

4. The AHF production tail gas stage scrubbing device according to claim 1, characterized in that: The first tail washing tower (2) is connected to the sewage tank (5) via the first vent valve (10); the second tail washing tower (3) is connected to the sewage tank via the second vent valve (11).

5. The AHF production tail gas stage scrubbing device according to claim 1, characterized in that: The exhaust pipe (15) is equipped with a check valve (13).

6. The AHF production tail gas stage scrubbing device according to claim 1, characterized in that: One end of the tail gas pipe (15) is connected to the hydrogen fluoride production device (1), and the other end is connected to the tail gas coil (17), which is located inside the first tail washing tower (2).

7. The AHF production tail gas stage scrubbing device according to claim 6, characterized in that: The exhaust coil (17) is provided with aeration holes (18).

8. The AHF production tail gas stage scrubbing device according to claim 1, characterized in that: One end of the circulating water pipe (16) is connected to the circulating pump, and the other end is connected to the circulating water coil (20).

9. The AHF production tail gas stage scrubbing device according to claim 8, characterized in that: A sprayer (19) is provided on the circulating water coil (20).

10. The AHF production tail gas stage scrubbing device according to claim 1, characterized in that: The second tail washing tower (3) is equipped with a gas discharge port (14) and a gas detector at the top.

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