Views: 6 Author: China Xicheng Publish Time: 2021-04-15 Origin: China Xicheng
There are roughly seven main methods used in treating waste gas in pesticide plants, which are chemical absorption method, lye method, iron salt method, carbon tetrachloride method, photolysis purification method, activated carbon adsorption method, plasma method, etc., respectively. The following is a relatively simple description of several waste gas treatment methods commonly used in pesticide factories.
1. Chemical absorption method: most commonly used absorbents are sodium hydroxide, calcium hydroxide, ferrous sulfate, iron chloride, carbon tetrachloride, sulfur chloride, etc.;
2. Lye method: When the amount of chlorine in the exhaust gas is low, lye or lime milk is generally used for neutralization and absorption. The obtained calcium hypochlorite and sodium hypochlorite solution can be used as a pulp bleaching agent, water treatment oxidant, disinfectant, disinfectant, etc.;
3. Iron salt method: The domestic chemical absorption method used to treat chlorine gas is also the ferrous sulfate method and the ferrous chloride method—the process of treating chlorine-containing waste gas with ferrous chloride solution. After being washed with water, the chlorine-containing tail gas is introduced from the lower part of the absorption tower and is in countercurrent contact with the ferrous chloride solution sprayed from the upper part. A chemical reaction occurs. After two-stage series absorption, the chlorine content in the discharged tail gas is less than 10mg/m3. The reaction produces ferric chloride, which can be used as a catalyst, waterproofing agent, etc. after processing;
4. Carbon tetrachloride method: When the chlorine content in the waste gas is greater than 10g/m3, the technique of carbon tetrachloride or sulfur chloride absorption can be used to recover the chlorine. The absorption tower adopts a spray tower or a packed tower, and then decomposes the absorption liquid in the absorption tower to decompose the chlorine by heating or decompressing, and then recycles it, absorbs and recycles it;
5. Photolysis purification method: photooxidation exhaust gas purification equipment is a unique treatment method that uses a particular ultraviolet band (C band), under the action of a particular catalytic oxidant, to break exhaust gas molecules and further redox. Exhaust gas molecules first pass through particular ultraviolet light waves to break organic molecules and break their molecular chains; at the same time, by decomposing oxygen and water in the air, high concentration ozone is obtained. Ozone further absorbs energy from free hydroxyl groups with higher oxidation performance and oxidizes the exhaust gas molecular. At the same time, a variety of composite inert catalysts are configured according to different exhaust gas components, which significantly improves the speed and efficiency of exhaust gas treatment to achieve the purpose of purifying exhaust gas;
6. Activated carbon adsorption method: The exhaust gas is adsorbed by Activated carbon adsorption tower. When the adsorption is saturated, the activated carbon needs to be desorbed and rebuilt, or replaced. It is currently the most used purification treatment technology for industrial organic waste gas in my country;
7. Plasma method: During the dielectric barrier discharge process in the plasma exhaust gas purifier.
Pesticide plant waste gas treatment equipment process
1. The malodorous gas collected by the collection pipeline is sent to the pretreatment system by the exhaust system-double purification tower. The odor is entirely in contact with the deodorizing liquid in the packed scrubber purification tower. The mass transfer between the gas and liquid phases is carried out at the interface between liquid and gas on the surface of the filler. A membrane of water molecules surrounds the malodorous particles in the air or water. At this time, the deodorization must first destroy the membrane of water molecules and then capture the malodorous particles. In the double purification tower, the acid gas and alkaline gas are removed, and part of the soluble organic gas is removed at the same time to reduce the back-end processing pressure.
2. The captured exhaust gas enters into the photocatalysis, under the action of UV light, the catalytic decomposition device is finally converted into CO2 and H2O.
3. After exiting the photocatalytic device, the exhaust gas enters the next-level purification device through the fan. The exhaust gas contains a certain amount of ozone, which will affect the back end. Therefore, a simple humidification method is used to remove the ozone in it to ensure that the exhaust gas is discharged through the chimney up to the standard.