What equipment is needed for spray booth exhaust gas treatment?阅读：5852 更新时间：2019-10-16 15:22 Source: Environmental Protection Machinery Co., Ltd. Longxin reading: 5852 Updated: 2019-10-16 15:22
The exhaust gas generated during the painting process is a great harm to human beings. During spray painting, paint mist and organic waste gas pollution are mainly generated. The paint is atomized into particles under the action of high pressure. When spraying, part of the paint does not reach the surface of the sprayed object, and the paint mist diffuses with the airflow. Thinner (organic solvent) is used to dilute the paint to achieve the purpose of smooth appearance of paint mist surface. Organic solvents are volatile, which will gradually evaporate during the process of painting and drying to form organic waste gas.
Project basic situation
In response to the exhaust gas pollution problem pointed out by your company, Shandong Longxin Environmental Protection Machinery Technology Co., Ltd. makes the following plan. The amount of air volume is 25000m3 / h according to your company, and the paint used is oily paint.
Design basis for environmental indicators
The design of the plan is based on the data provided for your company and your company's related requirements, combined with our accumulated experience in the purification of various pollution control oils, paints, mists, exhaust gases and dust in industrial workshops.
The design follows the principles of advanced technology, mature, economic, reliable and practical:
1. Improve the service life of the equipment and reduce the concentration of exhaust emissions;
2. Equipment selection is based on the principles of excellent technical performance, stable and reliable operation, convenient maintenance and repair, and easy purchase of spare parts;
3. Responsible for the integrity, advancedness and reliability of the organic exhaust emission reduction system;
4. Fully consider the investment and maintenance costs of the system.
5. Reduce system energy operation costs.
6. Meet the relevant national regulations and mandatory provisions.
7, using advanced and reliable automatic control technology, so that the exhaust gas can complete automatic processing.
8.The technological process is advanced, simple and reliable, which is convenient for operation and management.
Source of exhaust gas:
During spray painting, paint mist and organic waste gas pollution are mainly generated. The paint is atomized into particles under the action of high pressure. When spraying, part of the paint does not reach the surface of the sprayed object, and the paint mist diffuses with the airflow. Thinner (organic solvent) is used to dilute the paint to achieve the purpose of smooth appearance of paint mist surface. Organic solvents are volatile, which will gradually evaporate during the process of painting and drying to form organic waste gas.
Characteristics of exhaust gas:
1. Depending on the formula of the paint, the content of the material composition is complex;
2. The paint poisoning substances are: benzene, toluene, xylene, glycol ether, toluene diisocyanate, heavy metal, phthalate, VOC, formaldehyde, etc.
3. Benzene and benzene series in the spray paint exhaust gas are not easily soluble in water under normal conditions, the benzene ring is quite stable, difficult to oxidize, and have high thermal stability. The fine and viscous paint particles in the spray paint exhaust gas are not easy to dilute. Easy to cause filter clogging.
Hazard of exhaust gas:
The organic solvents benzene, toluene, and xylene in paint mist are highly toxic solvents. They are emitted into the workshop air during operation. After inhalation by workers through the respiratory tract, they can cause acute and chronic poisoning, mainly causing damage to the central nervous system and hematopoietic system. Short-term inhalation of high concentration of benzene vapor (1500mg / m3); can cause aplastic anemia: regular inhalation of low concentration of benzene vapor can also cause neurological symptoms such as nausea, vomiting, and blurred consciousness, and a few can cause neurasthenia . Toluene is more toxic to zhoong's central nervous system than benzene, and has less effect on the hematopoietic system than benzene. According to reports, when benzene mass concentration is 188-375mg / m3, long-term exposure can cause obvious symptoms. The chronic harm of toluene is less than that of benzene. At a concentration of 430-1300mg / m3, symptoms of poisoning can occur. Triphenyl mixture can also cause irritation to the eyes and nasal mucosa, and the neurological symptoms are more serious. The harm of spray painting to workers cannot be ignored. Enterprises need to take practical measures to control the exhaust gas of paint spraying to reduce the emission of pollutants and reduce the health hazards of toxic and harmful substances to the workers in the spraying workshop.
Comparison of advantages and disadvantages of common processing methods:
Activated carbon adsorption technology is currently the most widely used volatile organic gas purification technology. It is economical and practical, and has a wide range of applications. After activated carbon adsorption is saturated, the adsorption efficiency is very low, and the activated carbon needs to be replaced or desorbed regularly. Use alone cannot meet the requirements of emission standards, and it is recommended to use it with other purification technologies.
The absorption liquid absorption technology passes the vocs exhaust gas through the liquid absorbent, and uses the dissolution characteristics of vocs to purify the exhaust gas. Common equipment is washing tower and spray tower. The entire absorption equipment has a simple structure, a closed space, and a long life. It requires post-treatment of the adsorbent, and there will be secondary pollution. It can efficiently remove soot, dust and smoke from the exhaust gas, but The use cannot meet the requirements of emission standards, and it is recommended to use it with other purification technologies.
The photocatalytic technology uses a photocatalyst to contact volatile organic compounds. After being exposed to light, the catalyst generates electron-hole pairs. After oxidation and other reactions, carbon dioxide and water are generated on the surface. The application range is wide, the odor treatment effect is good, and it is suitable for lower concentrations of organic compounds. Gas purification. If the entire system uses only photocatalytic technology, the cost of using it alone is high. It is recommended to use it with other purification technologies.
Plasma technology uses high-energy electrons in the plasma generated during the gas discharge process to destroy the original structure of the volatile gas molecules, thereby changing its properties; at the same time, active groups such as ions and excited atoms are generated. These active groups It also acts on the molecules and fragments of volatile organic gases, and plays the role of dissociation, ionization or direct degradation of vocs, so that the large molecules of vocs are dissociated into small molecules such as carbon dioxide and water. The purification effect is good. Good purification effect, suitable for lower concentration organic gas purification, not suitable for high concentration exhaust gas purification, and requires regular maintenance when used alone, it can efficiently purify voc organic exhaust gas such as benzene series, non-methane total hydrocarbons, etc. The use of the shower tower can better remove the smoke, dust and smoke in the exhaust gas.
Based on the data provided by your company, due to the different treatment methods of oily paint and water-based paint, the company has confirmed that the paint type is oily paint. Two methods of process ① or process ② can be used to complete the exhaust gas treatment. Your company's production status and compliance with emission requirements. The first set of schemes has high investment costs, low operating costs, no use of activated carbon, and no hazardous waste. The second set of solutions has low investment costs and large operating costs. Additional costs are required for the replacement of activated carbon, and activated carbon in the saturated state is hazardous waste, which requires professional institutions to handle. The specification of exhaust gas treatment is estimated to be 25000m3 / h. A treatment line is adopted, which uses centrifugal fan ventilation and negative pressure air intake. Exhaust gas treated by purification equipment is discharged through the chimney, and the height of the chimney is 15 meters.