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8 methods of painting exhaust gas treatment
- Jan 02, 2019 -

8 methods of painting exhaust gas treatment and its advantages and disadvantages, 

Help customers find the most suitable paint exhaust gas treatment system.


How to handle the issue of spray  booth's paint exhaust treatment, Guangzhou Qiangxin Environmental Protection Electromechanical Equipment Co., Ltd. specially prepared  some method for the treatment of paint exhaust gas and the advantages and disadvantages. At present, the treatment processes for organic waste gas mainly include: water spray method, isolation method, combustion method, absorption method, condensation method, plasma catalytic oxidation method, adsorption method, photocatalysis method and so on.


1.Water spray method

The principle is to separate the water-soluble or large-particle components in the exhaust gas by spraying the exhaust gas to achieve the purpose of separating the pollutants from the clean gas.

Advantages: Water resources are easy to obtain, and can be reused after filtration and sedimentation, which greatly reduces the waste of water resources. Water spray has a relatively high efficiency in dealing with large particle components, and is often used as a pretreatment for exhaust gas treatment.

Disadvantages: low purification efficiency, not suitable for dry material recycling; circulating water, such as poor treatment, easy to cause secondary pollution.


2.Adsorption method

The activated carbon is adsorbed to the surface of the organic gas to purify it.
Advantages: wide application, simple operation and low investment cost.
Disadvantages: The system wind pressure loss is large, which makes the energy consumption higher, the saturation point of the adsorbent difficult to grasp, the adsorbent capacity is limited, and the operating cost is high.


3.Isolation method

Through the special filter material, it is placed in the exhaust gas discharge process and mechanically isolated to achieve the treatment effect.

Advantages: high efficiency in paint mist treatment, no technical requirements, simple operation.
Disadvantages: Can not effectively remove organic matter.


4.Combustion method

The organic exhaust gas is directly burned by heating and high temperature to achieve the purpose of exhaust gas purification.
Advantages: simple operation, high efficiency, suitable for handling high concentration exhaust gas
Disadvantages: A large amount of thermal energy is required. For example, direct combustion of toluene requires about 8000c, which requires a large amount of energy, and is also prone to secondary pollution caused by NOX at high temperatures.


5.Absorption method

The absorption liquid and the exhaust gas are brought into contact with each other to dissolve harmful substances in the exhaust gas into the absorption liquid, thereby purifying the exhaust gas. The absorbent is treated separately.
Advantages: low investment, low operating costs and simple operation.
Disadvantages: low processing efficiency, instability, low purification efficiency, about 50%, difficult to meet relevant environmental requirements, suitable for low concentration organic waste gas, secondary pollution.


6.Condensation method

By condensing and cooling, when the temperature is lower than the condensation point of the harmful substance, the gaseous harmful substance is converted into a liquid state, which is separated from the air to be purified.
Advantages: stable operation and high purification efficiency.
Disadvantages: Large investment, high requirements for the environment and operators, and excessive energy consumption and high operating costs.


7.Plasma catalytic oxidation method

The plasma is the fourth state except for the solid, liquid, and gaseous states of the substance, and has electrical neutrality and high electrical conductivity within a macroscopic degree. The plasma contains a large amount of active electrons, ions, excited state particles, photons, and the like. As a result of the collision of these active particles and gas molecules, a large number of strong oxidizing radicals O•, OH•, HO2 and O3 with strong oxidization are generated; organic molecules are collided by high-energy electrons, excited and atomically broken to form small Fragment groups or atoms; O•, OH•, HO2, O3, etc. react with excited atoms, organic molecules, groups, radicals, etc., and finally oxidize and degrade organic molecules into CO, CO2 and HO2.
Advantages: Wide applicability, suitable for dealing with low concentration (<1 ~ 1000ppm), poisonous and odorous harmful gas, making up for the blanks that other technologies can't handle. And easy to operate.
Disadvantages: The single low-temperature plasma technology still has its shortcomings when dealing with harmful gases, such as not completely and completely converting harmful gases into harmless gases, with more by-products; and generating a large amount of ozone under oxygen plasma; High energy consumption; low removal efficiency.


8.Photocatalysis method

Photocatalysis is a photocatalytic process using TiO2 as a catalyst. The reaction conditions are mild, the photolysis is rapid, the products are CO2 and H2O or others, and the application range is wide, including hydrocarbons, alcohols, aldehydes, ketones, ammonia and other organic substances, all of which can pass TiO2. Photocatalytic removal.
Advantages: high purification efficiency, stable operation, high safety factor, no defect of replacing consumables
Disadvantages: Large one-time investment, suitable for low-concentration, high-volume painting waste gas treatment


note:
(1) The purification rate of activated carbon adsorption method can reach more than 95%. If there is no regeneration device, the operation cost is too high;
(2) The liquid absorption method has a purification rate of only 60%-80%. This method actually has low absorption efficiency and oil mist entrainment, and it is generally difficult to meet national emission standards, and there are secondary pollution problems;
(3) The catalytic combustion method can also achieve a purification rate of 95%, but it is suitable for treating organic waste gas with high concentration, small air volume and high exhaust gas temperature, and the concentration of "triphenyl" in the paint exhaust gas is generally lower than 300 mg/m3. It is also not suitable to use catalytic combustion.


In summary, various methods have advantages and disadvantages. An excellent processing technology must be a leader, avoiding shortcomings, and must be efficient, practical, low-energy, and easy to operate. Practice has proved that the use of either method alone can not achieve effective governance goals.


Our company independently develops an advanced exhaust gas purification equipment: safe and energy saving, no secondary pollution, so as to achieve the best and efficient treatment effect, has been widely used in chemical, printing, painting, electronics, plastics, rubber, coatings, pharmaceuticals Organic waste gas produced by the automobile, petroleum, and other industries.

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