Analysis of common waste gas treatment methods
Analysis of common waste gas treatment methods
Air pollution is one of the most prominent environmental problems in the world. The main source of pollutants is industrial waste gas. Because of different production processes, different kinds of pollutants are produced. Different kinds of pollutants should be treated by different processes.
Organic waste gas
1)Main sources: various organic waste gases are produced in industrial production, including hydrocarbons, alcohols, aldehydes, acids, ketones and amines. These exhaust gases come from a wide range of sources, including the exhaust of petrochemical and organic synthesis reaction equipment in some chemical industries, organic solvents in printing ink, mechanical spraying paint in machinery industry, odor of metal products, automobile spraying paint in automobile industry, exhaust of production equipment of drying furnace castings, exhaust of spraying equipment in hardware and private factories, etc.
2)Harm of organic waste gases: In production, the emission of organic waste gases has been a very prominent problem, the vast majority of organic waste gases are harmful to human health. If organic exhaust gas enters the human body through the respiratory tract and skin, it can cause temporary and sexual changes in human respiratory, blood, liver and other systems and organs, especially benzopyrene polycyclic aromatic hydrocarbons (PAHs), which can directly cause cancer and endanger human health.
Organic waste gases can also cause serious air pollution. When some organic substances enter the atmosphere, they form photochemical smog under certain conditions, causing secondary pollution; when some organic substances enter the stratosphere, they react with ozone under ultraviolet radiation, resulting in ozone hole; some organic substances have the dual nature of odor pollution and harmful gases; and some organic substances have the dual nature of odor pollution and harmful gases. It will cause greenhouse effect.
3）Waste gas treatment methods:
A. Water film dedusting + activated carbon adsorption method;
B. Dry filter dust removal + activated carbon adsorption method
C. Activated carbon adsorption + catalytic combustion method;
Acid mist waste gas
1) Main sources: acid and alkaline waste gases discharged from chemical industry, electronics, metallurgy, electroplating, textile (chemical fiber), food, machinery manufacturing and other industries, such as condiment food, acid making, pickling, electroplating, electrolysis, battery, etc.
2) The harm of acid fog waste gas: the air pollution caused by acid fog gas causes great harm to human body, especially the direct damage and indirect influence to the field workers, crops near the factory and soil are often unable to be measured by money.
3) Waste Gas Treatment Method: Water Film Packed Tower + Alkali (Acid) Liquid Absorption
Furnace Waste Gas and Black Smoke for Power Generation
1)Main sources: metal dust particles produced by melting furnace equipment in metal industry, die-casting industry and foundry industry, SO2 and NOX harmful gases produced by burning diesel oil (heavy oil), waste gases produced by burning diesel oil (heavy oil) during generator operation, etc.
2)Harm of melting furnace waste gas and generator black smoke: melting furnace waste gas and generator black smoke are the main causes of acid rain, resulting in greater atmospheric pollution, especially direct damage and indirect impact on field operators, crops near factories and soil.
3)Treatment methods: swirl water washing and spraying + alkali absorption
As for the black smoke from the exhaust gas of the furnace and the exhaust gas of the generator set, the current conventional method is to adopt the swirl plate water washing spray method. The swirl plate spray tower is adopted. The gas moves upward and downward at high speed in the tower, and contacts with the washing liquid ejected upward and downward. Because of the multi-layer swirl plate installed in the tower, it can increase the gas-liquid contact area and contact time, and make the exhaust gas and water in the tower and plate. Full contact on the surface. In the process of contacting with the spray water, the pollutant carbon black in the tail gas is sufficiently absorbed by water to be purified; gaseous pollutants such as NO_x and SO_2 in the tail gas make the spray water alkaline by adding a certain proportion of NaOH in the spray water. In the spray process, when the water contacts with the tail gas, chemical reactions occur, so that gaseous pollutants such as NO_x and SO_2 can be neutralized to achieve good treatment effect.
Kitchen Fume, Fireworks smoke
1) Main sources:
Oil fume is a kind of fume gas molecule produced by various kinds of manufacturers when cooking vegetables in kitchen. Fire smoke is harmful gas discharged when the stove burns completely or incompletely. It is mainly black smoke and dust with free carbon. It is flocculent and easy to adhere to solid substances. The rest are COX, SO2 and NOX, which belong to high concentration smoke and dust gas.
2) The harm of kitchen lampblack and fireworks:
Kitchen lampblack contains many substances which are harmful to human body, and it will increase the risk of lung cancer. Kitchen smoke is also one of the main air pollution. The gas is acidic. It is easy to form acid when it meets water. It will pollute water flow, soil and corrode buildings.
3) Governance methods:
A. Filtration and adsorption fume purification:
The filter-adsorption oil-fume purification equipment can adopt organic polymer composite fabrics or felt with high oil absorption performance, inorganic filter materials (hydrophobic perlite, ceramsite, coke, etc.) which can be used alone or in combination. The filter materials can be placed vertically or parallel to the direction of flue gas flow, and the purification efficiency needs to be more than 80%. 。
B. Electrostatic oil fume purification:
Electrostatic deposition method is to introduce oil fume into high-voltage electric field, so that particles in oil fume and fire smoke are charged, and under the action of electric field, they move to dust collector and deposit. The purification efficiency is usually over 85% and the pressure drop is small.
C. Low temperature plasma method:
The principle is to use high voltage electrostatic method and plasma field at the front end of the electrostatic field to degrade the soot particles by using a large number of free radicals stimulated by its high energy, so that the viscosity of soot particles decreases. In the process of plasma production, the instantaneous high energy generated by high frequency discharge can open the chemical bonds of some harmful gases and make them decompose into simple atoms or harmless molecules. The technology is an advanced treatment technology for oil fume and pyrotechnics on the market. The removal rate is high (below 90%), the gas after treatment is odorless and easy to maintain, but the equipment investment is high.
B. Fireworks smoke
The high concentration kitchen smoke gas is sprayed by swirling plate water washing method. The swirling plate spraying tower is adopted. The gas moves up and down at high speed in the tower and contacts with the washing liquid ejected from up to down. Because of the multi-layer swirling plate in the tower, it can increase the gas-liquid contact area and contact time, and make the tail gas and water in the tower and in the tower. Full contact on the surface. In the process of contacting with the spray water, the pollutant carbon black in the tail gas is sufficiently adsorbed and purified by water; gaseous pollutants such as NO_x and SO_2 in the tail gas make the spray water alkaline by adding a certain proportion of NaOH in the spray water. In the spray process, when the water contacts with the tail gas, chemical reaction occurs, which causes gaseous pollution such as NO_x and SO_2. The material is neutralized to achieve good treatment effect.