Several commonly used industrial waste gas treatment methods
Atmospheric pollution is one of the most prominent environmental problems in the world. The main source of pollutants is industrial waste gas. Due to different production processes, industrial waste gas produces different types of pollutants. Different types of pollutants should be Use different processing techniques.
1. Organic waste gas
(1) Main sources: Various organic waste gases will be produced in industrial production, mainly including various hydrocarbons, alcohols, aldehydes, acids, Ketones and amines, etc. The sources of these waste gases are very wide, including exhaust gases from petrochemical and organic synthesis reaction equipment in the chemical industry, organic solvents in ink in the printing industry, mechanical spray paint in the machinery industry, odors generated by metal products, and automobile spray paint and drying furnace casting production equipment in the automotive industry. Exhaust, exhaust from spraying equipment in hardware and furniture factories, etc.
(2) Harm of organic waste gas: In production, the emission of organic waste gas has always been a very prominent problem. Most organic waste gas is harmful to human health. Organic waste gas can also cause serious air pollution.
(3) Exhaust gas treatment methods:
a. Water film dust removal activated carbon adsorption method;
b. Dry filtration dust removal activated carbon adsorption method;
c. Activated carbon adsorption catalytic combustion method;
2. Acid mist exhaust gas
(1) Main sources: chemical industry, electronics, metallurgy, electroplating, textile ( Chemical fiber), food, machinery manufacturing and other industries emit acid and alkaline waste gases, such as seasoning food, acid making, pickling, electroplating, electrolysis, batteries, etc.
(2) Harm of acid mist exhaust gas: Atmospheric pollution caused by acid mist gas causes greater harm to the human body, especially direct damage to on-site operators, crops and soil near the factory, and Indirect impacts often cannot be measured in monetary terms.
(3) Waste gas treatment method: water film packed tower alkali (acid) liquid absorption.
3. Furnace exhaust gas and power generation black smoke
(1) Main sources: metal dust particles and combustion generated by furnace equipment in the metal melting process in the hardware industry, die-casting industry, and foundry industry SO2 and NOX harmful gases generated during the diesel (heavy oil) process, exhaust gases generated during the combustion of diesel (heavy oil) when the generator is working, etc.
(2) Harm of furnace exhaust gas and generator black smoke: Furnace exhaust gas and generator black smoke are the main causes of acid rain, causing greater air pollution, especially to on-site operators and factories. Cause direct damage and indirect effects to nearby crops and soil.
(3) Treatment method: cyclonic water washing and spraying method for alkali absorption
For furnace exhaust gas and exhaust black smoke from generating units, the current common practice is to use cyclonic flow The plate water washing spray method uses a swirling plate spray tower. The gas moves from bottom to top in the tower at high speed and comes into contact with the washing liquid sprayed from top to bottom. Since there are multiple layers of swirling plates in the tower, it can Increase the gas-liquid contact area and contact time to fully contact the exhaust gas and water in the tower and on the plate. The pollutant carbon black in the exhaust gas is fully adsorbed by the water during the contact with the spray water and can be purified; gaseous pollutants such as NOx and SO2 in the exhaust gas are made alkaline by adding a certain proportion of NaOH to the spray water. , during the spraying process, when water contacts the exhaust gas, a chemical reaction occurs, neutralizing gaseous pollutants such as NOx and SO2 to achieve good treatment effects.
4. Kitchen fumes and fire smoke
(1) Main sources: Oil fumes are fume gas molecules produced by various manufacturers when cooking in the kitchen. Fire smoke is harmful gases emitted when stoves burn completely or incompletely. It is black smoke mainly composed of free carbon, which is flocculent and easily adheres to solid materials. The rest is COX, SO2, and NOX, which are high-concentration smoke gases.
(2) Harm of kitchen fume and fire smoke: Kitchen fume contains many substances that are seriously harmful to the human body and can increase people's chances of suffering from lung cancer. Kitchen fire smoke is also one of the major air pollutants. The gas is acidic and easily forms acid when it meets water, which will pollute water flow and soil and corrode buildings.
(3) Treatment methods:
A. Oil fume
a. Filter adsorption type oil fume purification: Filter adsorption type oil fume purification equipment can be used with high Organic polymer composite fabrics or felts with oil-absorbing properties, inorganic filter materials (hydrophobic perlite, ceramsite, coke, etc. used alone or in combination), the filter materials can be placed perpendicular or parallel to the flow direction of the flue gas to improve the purification efficiency Need to reach more than 80%.
b. Electrostatic oil fume purification: The electrostatic deposition method is to introduce the oil fume gas into a high-voltage electric field to charge the particles in the oil fume and fire smoke, and move towards the dust collecting pole under the action of the electric field force and deposit them. . The purification efficiency can usually reach more than 85, and the pressure drop is small.
c. Low-temperature plasma method: The principle is to use high-voltage electrostatic method and at the same time set up a plasma field at the front end of the electrostatic field, and use a large number of free radicals excited by its high energy to degrade the oil fume particles. Reduce its viscosity; during the plasma generation process, the instantaneous high energy generated by high-frequency discharge can open the chemical bonds of some harmful gases and decompose them into elemental atoms or harmless molecules. This technology is currently the most advanced oil fume and fire smoke treatment technology on the market. It has a high removal rate (less than 90%). The treated gas has no odor and is easy to maintain, but the equipment investment is high.
B. Fire smoke
For high-concentration kitchen fire smoke gas, the cyclone plate water washing spray method is used, and the cyclone plate type spray tower is used. The gas is discharged from the bottom in the tower It moves upward at high speed and comes into contact with the washing liquid sprayed from top to bottom. Since the tower is equipped with multi-layer cyclone plates, it can increase the gas-liquid contact area and contact time, so that the tail gas and water can circulate in the tower and on the plate surface. full contact. The pollutant carbon black in the exhaust gas is fully adsorbed by the water during the contact with the spray water and can be purified; gaseous pollutants such as NOx and SO2 in the exhaust gas are made alkaline by adding a certain proportion of NaOH to the spray water. , during the spraying process, when water comes into contact with the exhaust gas, a chemical reaction occurs, neutralizing gaseous pollutants such as NOx and SO2 to achieve good treatment effects.