Suzhou olefins | How is the role of organic waste gas treatment equipment?
The paint mist mainly comes from the scattered part of the solvent-based paint in the air spray operation, and the composition of the waste gas treatment equipment is common with the applied paint. Organic solvents are mainly derived from solvents and thinners in the process of coating application. Most of them are evaporative emissions. The primary pollutants are xylene, benzene, toluene and so on.
Painting refers to covering the maintenance layer or decoration layer on the metal and non-metal exterior, which is the most basic skill for the maintenance and decoration of the product. The coating process can be easily summarized as: pretreatment → spray → boring or curing. Pretreatment generally includes degreasing, descaling, and passivation (phosphating) processes. For different coatings and anti-corrosion requirements, degreasing, descaling, phosphating and other treatment methods should be selected according to the raw materials of the workpiece. In the pre-treatment descaling process, sandblasting, shot blasting or sanding processes are also available on demand in different sectors of different occupations.
With the rapid development of painting skills, the automatic production of painting has made significant progress, and the electrostatic spraying, electrophoretic painting and powder coating skills have been applied. However, the current coatings are also selected for organic solvent-based coatings.
According to the coating production process, the coating waste gas mainly comes from the pre-treatment, spraying and boring process. The pollutants discharged are mainly: dust or acid mist generated in the pre-treatment process, paint mist and organic solvent generated during painting, boring Organic solvent that occurs when evaporating. The paint mist is mainly derived from the scattered parts of the solvent-based paint in the air spray operation, and its composition is common with the applied paint. Organic solvents are mainly derived from solvents and thinners in the process of coating application. Most of them are evaporative emissions. The primary pollutants are xylene, benzene, toluene and so on. The harmful exhaust gas emitted in the painting is mainly concentrated on the paint production line, and the spray booth, the drying room and the drying room are the primary sources of exhaust gas.
2. Painting exhaust gas treatment measures
The management of paint exhaust gas can be divided into two ways of prevention and treatment. The first priority is to reduce emissions of waste gas. The first priority is to clean and manage the inevitable emissions.
2.1 Reduce exhaust emissions
2.1.1 Source control, reducing the use of organic solvents
In order to reduce the exhaust emissions during the coating process, it is possible to start from the source, and it is not necessary to use or use a coating containing organic solvents, such as powder coatings, water-based coatings, and high-solids coatings. Powder coatings do not use organic solvents. In addition to the occurrence of paint dust, the coating process does not emit harmful exhaust gas. Therefore, it has developed rapidly in recent years and the application range has been greatly increased. Water-soluble coatings and high-solids coatings are also effective in reducing harmful emissions during the coating process, which is a trend in the coatings industry. In the painting process, paints with high solid content coatings or without organic solvents are selected. Although the coatings are more expensive, they reduce organic solvent emissions, reduce the difficulty of exhaust gas treatment and the planning of treatment facilities, and are compatible with clean production and energy saving. Requirements for emission reduction.
2.1.2 Improve the use rate of paint, reduce the amount of use
Spraying is a common method in coating production. However, the paint sprays more fog, and the paint evaporates into the air in the form of paint mist.
The coating power is affected by many factors, and the coating power of these coating methods is high when painting large-area workpieces. However, as long as the large-capacity low-pressure air spray gun (HVLP) and electrostatic spraying are satisfactory, 60% of the coating power is satisfied. In addition, the use of robotic spray and rotary atomization methods can improve the use of paint.
2.2 Management of exhaust emissions
For the exhaust gas from the painting, an appropriate method can be used for purification management. There are two ways to purify the management. One is to recycle the organic solvent in the exhaust gas, and the other is to differentiate the organic solvent in the exhaust gas into CO2 and H2O.
2.2.1 Recycling of organic solvents
The paint mist and the evaporated organic solvent that occur during the coating process are primarily organic solvents that can be recycled. The recovery methods include activated carbon adsorption, liquid absorption and condensation.
2.2.2 Organic solvent differentiation
It refers to the differentiation of organic solvents into CO2 and H2O. Methods for differentiating organic solvents include incineration, catalytic incineration, ultraviolet-ozone, and microbial differentiation.