Injection molding is a technology commonly used in modern plastics processing. Products usually use rubber injection and plastic injection. During the operation process, the waste gas produced by the process will be destroyed if there is no effective treatment.

Injection molding machine produces organic waste gas in the process of injection heating. Its main components are dust particles, non methane total hydrocarbons and other harmful substances. The exhaust gas has a stimulant odor, a little toxicity, and has great harm to the health of the human body. Unorganized emissions of styrene, toluene, organic waste gas and so on will cause serious pollution to the environment, and will also cause great damage to human health. Therefore, the waste gas from the plastic plant production line has to be handled with caution.

At present, the main processes used in the treatment of injection waste gas are as follows:

1. Photocatalytic oxidation:

Photocatalytic oxidation technology is the use of special ultraviolet band, the gas molecules break down, break the chain, at the same time, through the decomposition of water in the air and oxygen, make it become the high activity of ozone or free hydroxyl groups to oxidation gas molecules into carbon dioxide and water. With the addition of catalyst, the rate of reaction and the efficiency of treating waste gas can be improved so as to achieve the purpose of purifying exhaust gas.

Photocatalytic oxidation technology is a kind of VOCs treatment method which is widely used and mature in technology.

2, carbon adsorption:

Carbon adsorption is the most widely used recovery technology at present. Its principle is to capture VOCs in exhaust gas by using porous structure of adsorbent (granular activated carbon and activated carbon fiber). The organic waste gas containing VOCs is passed through the activated carbon bed, and the VOsC is adsorbed by the adsorbent, and the exhaust gas is purified and discharged into the atmosphere.

When carbon adsorption reached saturation, the saturation of the carbon bed desorption regeneration; steam heating carbon layer, VOCs was blowing out, and the formation of steam mixture with water vapor, leaving carbon adsorption bed together with the condenser cooling steam so that the steam condenses into a liquid mixture. If VOCs is water-soluble, the liquid mixture is purified by distillation; if the water insolubility is insoluble, the precipitate is used to recover the VOCs directly. The three benzene and water used in the coating can not be dissolved in each other, so it can be recovered directly. Carbon adsorption technology is mainly used for exhaust gas components, relatively simple organic compounds with higher recycling value of waste gas treatment equipment, the size and cost of gas is proportional to the number of VOCs, but relatively independent from the exhaust gas flow; therefore, adsorption tends to dilute the amount of air logistics, generally used for VOCs concentration of less than 5000PPM the situation. It is suitable for the situation that the temperature is not high, the humidity is not high, and the amount of the exhaust is large, especially for the purification and recovery of the halogen.

3. Plasma catalytic oxidation:

Plasma catalytic technology has wide application scope and high purification efficiency. It is especially suitable for multi component odor gases, such as chemical industry, medicine and other industries, which are difficult to deal with by other methods. But the one-time investment is huge, and there is a certain risk of security.

Organic waste gas is activated by plasma, dissociated and activated. Then activated exhaust gas is catalyzed by oxygen on the surface of rare metal oxide and oxygen in exhaust gas, and finally transformed into carbon dioxide and water.

4. Incineration technology:

焚燒技術包括高溫焚燒和催化燃燒，在國外較為成熟應用也較為廣泛，適合處理高濃度、小風量的VOCs，對整個技術的安全性與氣密性要求較高。 In the process of handling large air volume and low concentration of VOCs, relevant concentration technology should be used for pretreatment.

The principle of work: high temperature incineration is to burn the organic components in the exhaust gas to produce carbon dioxide and water at high temperature. Catalytic combustion is to reduce the temperature required for reaction by means of catalyst when burning, so that exhaust gas can be regenerated at room temperature to generate carbon dioxide and water.