Views: 5 Author: China Xicheng Publish Time: 2021-06-28 Origin: China Xicheng
Air pollution is one of the most prominent environmental problems in most countries. 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 use different treatment processes.
1. Waste gas from agricultural production system
Main sources: Industrial production will produce waste gas from various agricultural production systems, including various hydrocarbons, alcohols, aldehydes, acids, ketones and amines. The sources of these exhaust gases are very wide. Some of them are exhaust gas from synthetic reaction equipment in petrochemical and agricultural production systems in the chemical industry, solvents in agricultural production systems in printing inks in the printing industry, mechanical painting in the machinery industry, odors generated by metal products, and the painting and drying of automobiles in the automobile industry. Exhaust for furnace casting production equipment, exhaust for spraying equipment in hardware and furniture factories, etc.
Harm of waste gas from agricultural production system: In production, the emission of waste gas from agricultural production system has always been a very prominent problem. Most of the waste gas from agricultural production system is harmful to human health. For example, after the waste gas of agricultural production system enters the human body through the respiratory tract and appearance, it can cause temporary and lesions to human breathing, blood, liver and other systems and organs, especially benzopyrene polycyclic aromatic hydrocarbons can directly cause cancer in the human body and endanger human health .
Waste gas from agricultural production systems can also cause serious air pollution. After some agricultural production systems enter the atmosphere, they form photochemical smog under certain conditions, causing secondary pollution; some agricultural production systems enter the stratosphere, and photochemically react with ozone under ultraviolet radiation, resulting in a hollow ozone layer; some agricultural productions System substances have the duality of odor pollution and harmful gases; there are also some agricultural production system substances that can cause the greenhouse effect.
Waste gas treatment method:
a. Water film dust removal and activated carbon adsorption method;
b. Dry filter dust removal, activated carbon adsorption method
c. Activated carbon adsorption catalytic combustion method;
2. Acid mist exhaust gas
Main sources: acid and alkaline waste gas discharged from the chemical industry, electronics, metallurgy, electroplating, textile (chemical fiber), food, machinery manufacturing and other industries, such as seasoning food, acid production, pickling, electroplating, electrolysis, storage batteries, etc.
The harm of acid mist exhaust gas: The air pollution caused by acid mist gas causes greater harm to the human body, especially the direct damage and indirect impact to the operators on the site, the crops near the factory, and the soil. It is often impossible to measure with money. .
Waste gas treatment method: water film packed tower, alkali (acid) liquid absorption.
3. Furnace exhaust gas, power generation black smoke
Main sources: metal dust particles generated in the metal melting process of the hardware industry, die casting industry, and foundry industry furnace equipment, SO2 and NOX harmful gases generated in the process of burning diesel (heavy oil), and the process of burning diesel (heavy oil) when the generator is working Exhaust gas generated, etc.
The hazards of furnace exhaust gas and generator black smoke: furnace exhaust gas and generator black smoke are the main causes of acid rain, which cause large air pollution, especially direct damage to the operators, crops and soil near the factory. Indirect effects.
Treatment method: swirling water washing spray method, lye absorption
For the furnace exhaust gas and the exhaust black smoke from the generator set, the current conventional method is to use the swirl plate water washing spray method and the swirl plate spray tower. The gas moves in the tower at high speed from bottom to top, and from top to bottom. The sprayed washing liquid contacts, because the multi-layer cyclone plate is arranged in the tower, it can increase the gas-liquid contact area and contact time, so that the tail gas and the water are fully contacted in the tower and the plate surface. The pollutant carbon black in the exhaust gas is fully absorbed by the water during the contact with the spray water to be purified; the gaseous pollutants such as NOx and SO2 in the exhaust gas are alkaline by adding a certain proportion of NaOH to the spray water , In the spraying process, when the water contacts the tail gas, a chemical reaction occurs to neutralize gaseous pollutants such as NOx and SO2 to achieve a good treatment effect.
4. Kitchen fume, fire smoke
Main source: Oil fume is the gas molecules of oil fume produced when cooking in the kitchens of various manufacturers. Fire smoke is the harmful gas emitted when the stove is completely or incompletely burned. It is black smoke and dust 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 and dust gases. .
The hazards of kitchen oil fume and fire smoke: Kitchen oil fume contains many substances that are harmful to the human body, which will increase the chance of people suffering from lung cancer. Kitchen fire smoke is also one of the main air pollution. The gas is acidic, and it is easy to form acid when it meets with water, which will pollute water and soil and corrode buildings.
A. Oily smoke
a. Filtration and adsorption type oil fume purification: filter and adsorption type oil fume purification equipment can use agricultural production system polymer composite fabrics or felts with high oil absorption performance, inorganic filter materials (hydrophobic perlite, ceramsite, coke, etc.) Or used in combination), the filter material can be placed in a direction perpendicular or parallel to the flow direction of the flue gas, and the purification efficiency needs to be more than 80%.
b. Electrostatic oil fume purification: The electrostatic deposition method introduces oil fume into a high-voltage electric field, so that the particles in the oil fume and fire fume are charged and move to the dust collector under the force of the electric field 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 the high-voltage electrostatic method at the same time, set a plasma field at the front end of the electrostatic field, and use the large amount of free radicals excited by its high energy to degrade the oil fume particles and reduce the viscosity; in the plasma During the production process, the instantaneous high energy generated by the high-frequency discharge can open the chemical bonds of some harmful gases and decompose them into elemental atoms or harmless molecules. This technology is an advanced oil fume and fire fume treatment technology currently on the market, with a high removal rate (less than 90%), the treated gas has no peculiar smell, and it is convenient to maintain, but the equipment investment is high.
B. Fire and smoke
For high-concentration kitchen fire smoke gas, the swirl plate water washing spray method is adopted, and the swirl plate spray tower is adopted. The gas moves at high speed from bottom to top in the tower, and contacts the washing liquid phase sprayed from top to bottom. A multi-layer cyclone plate is installed in the tower, which can increase the gas-liquid contact area and contact time, so that the tail gas and water are fully contacted in the tower and on the plate surface. The pollutant carbon black in the exhaust gas is fully absorbed by the water during the contact with the spray water to be purified; the gaseous pollutants such as NOx and SO2 in the exhaust gas are alkaline by adding a certain proportion of NaOH to the spray water , In the spraying process, when the water contacts the tail gas, a chemical reaction occurs to neutralize gaseous pollutants such as NOx and SO2 to achieve a good treatment effect.