Acid mist purification device

Acid mist purification deviceDeveloping the concept of sulfurization bed into vapor-liquid mass transfer equipment, the packing in the water spray purification tower is in a fluidized state, thereby enhancing the mass transfer process. The characteristics of the acid mist purification device are: high gas velocity, large processing capacity, light weight of the tower, relatively uniform distribution of vapor and liquid, and not easily blocked by solid and viscous materials. Especially due to the strong turbulence inside the tower, the mass and energy transfer are strengthened, which can greatly reduce the tower diameter and height. The tower handles a large amount of air flow, resulting in an empty tower gas velocity1．5～6．0m/sSpray density20～110m3/(m2·h）Pressure loss1 500～3 800PaThe dehazing device of the water spray purification tower adopts a cyclone plate dehazing device, which uses the centrifugal force to remove the mist by rotating the gas through the tower plate, and its dehazing efficiency can reach98%-99%Moreover, the structure is simple and the pressure drop is small.

Structure of acid mist purification device:

This equipment is divided into single tower and double tower. It adopts a circular tower body and is connected in sections with flanges. Specifically, it consists of a liquid storage tank, tower body, air inlet section, spray layer, packing layer, cyclone defogging layer, observation window, air outlet, etc.

1The flow rate design of acid mist purification device needs to be based on the properties of exhaust gas and actual application requirements. The general design rules are as follows:

Cyanide containing waste gas,Vtake0.3-0.6m/sThe duration of stay is taken as8-10s；

②Chromium containing waste gas,Vtake0.3-0.6m/sThe duration of stay is taken as9-12s；

③Ammonia containing waste gas,Vtake0.3-0.6m/sThe duration of stay is taken as7-12s；

④Acidic waste gas（HClSulfuric acid mist),Vtake1m/sThe duration of stay is taken as5-6s；

⑤containNOXExhaust gas,Vtake0.3-0.6m/sThe duration of stay is taken as8-10s；

⑥containHFExhaust gas,Vtake0.3-0.6m/sThe duration of stay is taken as9-12s(It is not advisable to use packed towers, as fluoride is often insoluble or difficult to dissolve substances, which can cause blockages. Usually, cyclone plate towers or empty towers are used.);

⑦Dust containing gas (with dust removal as the main purpose) is treated using a horizontal spray tower,Vtake0.8-1.0m/sThe duration of stay is taken as3-4s；

⑧Organic waste gas (dissolved in water, acid or alkali, and removed by enhancers such as sodium hypochlorite),Vtake0.4-0.6m/sThe duration of stay is taken as8-12s；

2The liquid to gas ratio of the acid mist purification device is generally based on2.0-2.5L/m3Design;

3Treatment methods for various types of exhaust gases:

①Chromium containing waste gas

A combination of filtration recovery pretreatment and wet spray deep treatment is required. The use of a network format chromium acid mist recovery device can preliminarily recover waste gas from workers60%-80%Chromic acid needs to be treated with spray absorption and purification in order to meet emission standards. Highly toxic hexavalent chromium can be reduced to less toxic trivalent chromium through sulfite solution:

H2CrO7＋3Na2SO3＋3H2SO4→Cr2(SO4)3＋3NaSO4＋4H2O

②Nitrogen oxides（NOX）

Nitric acid solution has strong oxidizing and unstable properties, and its oxide forms are diverse. Its purification requires the action of its reducing agent to react and generate stableN2.

2NO＋O2→2NO2

2Na2S2O3＋NO2＋2 NaOH→2N2↑＋4 Na2SO4＋2H2O

③Treatment of acidic and alkaline waste gas

Due to the water solubility of this type of exhaust gas, it is easily absorbed by water, so the absorption method can achieve good removal effects for this type of exhaust gas. Acidic waste gas is absorbed by alkaline solution, while alkaline gas is absorbed by acid solution. For example, sulfuric acid waste gas can be neutralized and absorbed with sodium hydroxide solution or ammonia solution, while ammonia containing waste gas can be directly absorbed with water to generate ammonia solution. The reaction equation is as follows:

H2SO4 +2NaOH → Na2SO4 + 2 H2O

NH3+H2O→ NH3·H2O

④Treatment of cyanide containing waste gas

There are two methods: adding anti fog agents or using absorption methods for treatment. However, due to the use of anti fog agents, it may affect the washability and subsequent processes, resulting in poor electroplating effects and therefore not being used frequently. Due to the fact that hydrogen cyanide can be absorbed by various substances, the current common practice is to use wet methods to absorb cyanide containing waste gas. Cyanide waste gas is available1.5%Sodium hydroxide and sodium hypochlorite solution are absorbed. When using sodium hypochlorite aqueous solution as the absorbent, sodium hydroxide should be used to adjust the absorbentPHMaintain in a weakly alkaline state, absorb with a general spray tower, and achieve purification efficiency of up to90%Above, the processed products are nitrogen, carbon dioxide, and sodium chloride. The reaction equation is as follows:

2NaClO + CN- → CO2 + N2 + 2NaCl

⑤Fluorine containing waste gas

Absorption method (wet) and adsorption method (dry) can be used. The adsorption method is physical adsorption, and general adsorbents are not easy to adsorb wellHFMoreover, adsorbents have disadvantages such as high prices, easy saturation, and high operating costs, making them rarely widely used in the market.

Absorption method uses alkaline solution as an absorbent to absorb fluoride through gas-liquid contact and mass transfer reaction. The control of customs clearance conditions can also generate economically beneficial by-products such as fluorosilicic acid (cryolite). The main principle is based on the solubility of hydrogen fluoride in water, and the second is based on the principle of acid-base neutralization. The advantages of absorption method are that the purification equipment has a small volume, stable purification efficiency, low investment and operating costs, and is commonly usedCa(OH)2absorbHF.

Precautions for installation of acid mist purification device:

1The main body, water pump, and fan of the acid mist purification device are recommended to be installed on a concrete foundation, and the equipment should be fixed with expansion bolts.

2If the equipment is installed and operated outdoors, anti freezing treatment should be considered for the bottom water tank of the equipment when the temperature drops in winter.

3The water tank of the equipment has a liquid level mark, and it is necessary to inject the absorbent according to the liquid level mark before use. During use, it is important to promptly replenish the absorbent solution.

4When using, the circulating water pump should be turned on first, and then the blower should be started. When stopping, the blower should be stopped first1-2Stop the circulating water pump again in minutes.

5Regularly check the depth of liquid in the equipment water tank and the degree of gas purification at the exhaust port based on usage, and promptly replace the absorbing liquid in the bottom water tank according to the operation of the equipment.

6This equipment should undergo maintenance once a year and a half to two years, checking the filling of the disc-shaped spray pipes and fillers, and cleaning them.

Acid mist purification deviceUse case:

Huakang Environmental Protection installs acid mist purification device for plastic factory

Scope of application of acid mist purification device:

For various corrosive gases, the purification treatment effect is significant and can effectively remove hydrogen chloride gas（HCl）Hydrogen fluoride gas（HF）Ammonia gas（NH3）Sulfuric acid mist（H2SO4）Chromium acid mist（CrO3）Cyanuric acid gas（HCN）Alkali vapor（NaOH）Hydrogen sulfide gas（H2S）Formalin（HCHO）Waiting for water-soluble gases. Organic and inorganic waste gas purification treatment in refineries, rubber factories, leather factories, printing factories, chemical factories, Chinese and Western pharmaceutical factories, metal casting factories, plastic factories, spray solvents, food processing factories, meat processing factories, slaughterhouses, poultry feed farms, paper mills, sewage treatment plants, garbage transfer stations, etc. Our company's independently developed turbulence tower has high purification efficiency, simple operation and management, and long service life. The acid and alkali waste gas emissions after purification treatment meet China's emission standards.