0 Preface In view of the increasingly stringent environmental protection requirements at the present time, the treatment of paint exhaust gas ends has become increasingly clear. The exhaust gas of the construction machinery coating line mainly comes from the exhaust gas in the booth, spray booth, leveling room, drying room and sewage treatment room. The concentration of these exhaust gases is generally within the emission limits. In order to meet the emission rate requirements in the standard, high-altitude emissions are a common method used by many construction machinery manufacturers. Although it is currently possible to meet the requirements of environmental emissions, high-altitude emissions are essentially direct emissions without any treatment of exhaust gas, and are harmful to the atmospheric environment. 1 exhaust gas treatment process comparison Since the types of exhaust gas are relatively large, the methods of treatment are also different. The condensation method, absorption method, combustion method, catalytic method, and adsorption method are commonly used methods in China; biological methods, low-temperature plasma methods, etc. are developed in recent foreign countries. A new technology, new process, a brief comparison of each process is introduced below. 1.1 Condensation recovery method This method requires that the concentration of organics in the exhaust gas is relatively high, generally in the tens of thousands or even hundreds of thousands of ppm. This method is not suitable for low concentration organic exhaust gas. Its basic principle is that the waste gas discharged from the coating line is condensed by the condenser, and then the condensed condensate is separated to separate the valuable and recoverable organic substances. 1.2 absorption method Chemical absorption and physical absorption are two forms of absorption, but chemical absorption is less common, because most of the exhaust cannot use chemical absorption. Physical absorption is mainly used in medium and high-concentration exhaust gas. Its principle is that the exhaust gas is discharged into the atmosphere after being absorbed by the material. When the absorbed fluid that is physically absorbed is saturated, it can be reused after being analyzed or distilled. The secondary pollution problem of this method is difficult to solve and the purification effect is not ideal [1]. 1.3 Direct combustion method The direct combustion process is relatively simple and suitable for the treatment of high concentrations of exhaust gas. Its principle is: the use of fuel to collect the exhaust gas mixture is heated, heated to 700 ~ 800 °C, and stay in the 0.3 ~ 0.5s, in the high temperature flammable hazardous substances can be decomposed into non-hazardous substances. 1.4 Catalytic combustion In this method, the exhaust gas is heated to 200-300°C and then converted into harmless and odorless carbon dioxide and water through catalytic catalytic combustion to achieve the purpose of purification. The method is applicable to the treatment of high temperature, medium and high concentration organic waste gas, and has been widely used at home and abroad with good results. This method is one of the effective methods for the treatment of organic waste gas, but there are disadvantages of large equipment investment and high operating cost for the treatment of organic waste gas with low concentration and large air volume [2]. 1.5 adsorption method 1) Direct activated carbon adsorption This method is relatively simple and the investment is small. It is the organic waste gas that will be excluded from the coating line and is adsorbed on activated carbon. The adsorption rate is above 90%. This method cannot be regenerated after the activated carbon reaches saturation, and it needs to be replaced regularly to ensure the purification effect. The replacement will result in secondary pollution during loading and unloading, transportation, etc. The cost of activated carbon is relatively high and the saturated activated carbon requires a special handling mechanism to handle it, resulting in higher processing costs, and therefore the direct cost of activated carbon adsorption is quite high. 2) Adsorption-recovery method The method utilizes superheated steam to reverse blow adsorption-adsorption-saturated adsorbents for desorption regeneration, and the steam and desorbed organic gases are condensed and separated to recover organic liquids. The purification efficiency of this method is higher, but it requires the necessary amount of steam. In addition, the separation of organic solvents and water is not very thorough, the quality of the mixed liquid obtained is not high, and the components are relatively complex. These organic liquids cannot be used directly in production, and distillation, rectification, extraction, and other multiple procedures are required. 3) New adsorption-catalytic combustion method This method mainly deals with the treatment of low-concentration, high-air-volume wastes, which combines the advantages of both adsorption and catalytic combustion methods. Its basic principle is: low-concentration coating line waste gas, first through the new type of activated carbon adsorption, after saturation, give it into the hot air heating, the organic waste gas from the activated carbon desorption, then the waste material from the low The concentration becomes a high-concentration exhaust gas, and these high-concentration exhaust gases are then sent to the catalytic combustion bed for combustion. This method is being promoted and approved, and it is a relatively effective method for exhaust gas treatment [2]. 1.6 Low-temperature plasma technology Low-temperature plasma technology is more suitable for the treatment of low-concentration, small-molecule exhaust gas. It is the fourth state following solid, liquid, and gas. When the voltage is applied to the gas ignition point voltage, the gas breaks down and a new mixture is created. body. The reason for the low-temperature plasma is that although the temperature of the electrons reaches a high level during the discharge process, the temperature of the heavy particles is low, resulting in the entire system showing a low temperature. Its principle is to use the generated high-energy electrons, free radicals and other active particles to act on the exhaust gas, so that a series of reactions such as decomposition of pollutants in the exhaust gas can occur, and then the purpose of decomposing the pollutants can be achieved. 1.7 Photocatalytic Technology Photocatalytic technology is one of the treatment methods suitable for low-concentration waste gas. It uses TiO2 as a catalyst, has relatively mild reaction conditions, fast photolysis, and photocatalytic products such as CO2, H2O or other, and its application range is compared. Wide, including aldehydes, ketones, ammonia and other organic waste, can use TiO2 for photocatalytic removal. The main mechanism is that the catalyst absorbs photons and reacts with water on the surface to produce a main active material. He plays a decisive role in the hydroxyl radical (?OH) of photocatalytic oxidation. It also produces a reactive oxygen species (?O, H2O2) [3]. 1.8 Comparison of Several Commonly Used Treatment Waste Gas Processes The application of several commonly used treatment technologies in the treatment of organic waste gas is shown in Table 1. 2 recommended process Taking the exhaust line of the coating line of the Bulldozer Division of Shantui Group as the research object, the exhaust gas treatment source consists of two parts, the liquid mist and the gaseous volatile organic compound. The paint mist particles are small, highly viscous and easily adhere to the surface of the material. Before the purification of organic waste gas, paint mist must be removed; volatile organic substances are mostly difficult to dissolve in water; discharge is discontinuous: mainly concentrated in the spraying operation period, and the exhaust gas concentration is low when not operating. The treatment of exhaust gas with a large amount of wind, low organic matter concentration, containing a certain viscosity paint mist and particulate dust and so on. Combine successful practice experience in the industry with Commercial Popcorn Machine,Flavored Popcorn Machine,Simple Operate Popcorn Machine,Caramerl Popcorn Machine Jinan RuiHan Trading Company Limited , https://www.ruihangroup.com