Paper Industry Exhaust Gas Composition
Exhaust gas control in the pulping process in paper mills is mainly in three areas: i. It is the odor generated in the pulp production process, which will be sent to the alkali recovery boiler for combustion after a completely sealed conveyor system, such as from the pulp line, evaporation tanks, causticizing and stripping tower of the NCG non-condensable gases, the composition of which contains sulfur-containing compounds such as H2S, CH3SH, CH3SCH3, CH3SSCH3, and some other turpentine, methanol, water vapor, nitrogen, oxygen, and some other The gas is corrosive, toxic and explosive.
Therefore, the air quality is bound to be affected to a large extent without the necessary recovery of NCG. Pulp and paper mills send the NCG generated in the system to be burned in the alkali recovery boiler, which not only eliminates its serious air pollution, but also effectively recovers sulfur. ii. It is the waste gas generated from pulp bleaching and preparation chemicals, all of which are chemically treated in the waste gas scrubber tower and converted into air non-polluting gases before being discharged into the atmosphere; iii.It is the dust generated from the combustion of power boilers, alkali recovery boilers and lime kilns, and high efficiency electrostatic precipitator is installed to remove the dust therein before the combustion exhaust is discharged.
Composition of exhaust gases from the spraying industry
Painting refers to the metal and non-metallic surfaces covered with a protective layer or decorative layer, is the most basic technical means used to protect and decorate the surface of the product. Painting process can be simply summarized as: pretreatment → spraying → drying or curing. Pre-treatment generally includes degreasing, descaling, passivation (phosphating) process. For different coatings and corrosion resistance requirements, degreasing, descaling, phosphating and other treatment methods depending on the status of the workpiece raw materials to choose. In the pre-treatment descaling process, sandblasting, shot blasting or grinding process, also in different sectors of different industries as needed.
With the rapid development of coating technology, coating automation production has made significant progress, electrostatic spraying, electrophoretic coating, powder coating technology has been applied to promote. However, the current coating used are still organic solvent-based coatings.
According to the coating production process, the coating exhaust mainly comes from the pretreatment, spraying and drying process, and the pollutants emitted are mainly: dust or acid mist generated in the pretreatment process, paint mist and organic solvents generated during spraying, and organic solvents generated during drying and evaporation. Paint mist mainly comes from the part of solvent-based paint flying off in air spraying operation, and its composition is consistent with the paint used. Organic solvents mainly come from the use of paint in the process of solvents, diluents, the vast majority of volatile emissions, and its main pollutants for xylene, benzene, toluene and so on. Harmful emissions from painting are mainly concentrated in the paint spraying production line, in which the paint spraying room, drying room and drying room are the main sources of emissions.
Leather industry exhaust gas composition
Leather exhaust source The main source of exhaust gas in the production process of synthetic leather is the volatilization of organic solvents: (1) the volatilization of resin and solvents in the batching, transportation and storage; (2) the volatilization of organic substances in the process of coating or impregnation; (3) the volatilization of organic substances in the heating of the oven; (4) the volatilization of organic substances in the process of post-treatment.Exhaust pollutants are related to the specific process and formulation composition. For a certain process, the formula can often be changed, so the specific pollutants produced are not fixed. General pollutants in the production process are: ① polyurethane dry process: organic solvents (DMF, toluene, xylene, butanone, etc.); ② polyurethane wet process: organic solvents (DMF); ③ PVC and other related processes: plasticizer fumes (dioctyl phthalate, etc.), vinyl chloride, hydrogen chloride, organic solvents, lead; ④ post-treatment process: organic solvents (DMF, toluene, xylene, butanone, butyl acetate, etc.), particulate matter; ⑤ microfiber process: organic solvents (DMF, toluene, xylene, butanone, acetate, etc.), particulates Butyl acetate, etc.), particulate matter; ⑤ Microfiber process: organic solvents (DMF, toluene, xylene, etc.)
Food Industry Exhaust Gas Composition
The food manufacturing industry is often accompanied by the production of a large number of organic waste gas, as well as the accompaniment of malodorous gases, the main components of which are hydrogen sulfide, methyl mercaptan, methyl sulfide, dimethyl disulfide, carbon disulfide, ammonia, trimethylamine, styrene and so on.
Chemical Industry Exhaust Gas Composition
The composition of chemical waste gas produced by different chemical production industries varies greatly. For example, the waste gas produced by the chlor-alkali industry mainly contains chlorine, hydrogen chloride, vinyl chloride, mercury, acetylene, etc., and the waste gas produced by the nitrogen fertilizer industry mainly contains nitrogen oxides, urea dust, carbon monoxide, ammonia, sulphur dioxide and methane.
Wastewater plant exhaust composition
The malodorous gases are mainly generated in the sewage treatment process at the sewage pumping station, inlet grating, sand sedimentation tank, regulating tank, primary sedimentation tank, etc.; in the sludge treatment process at the sludge thickening, dewatering and drying, transfer, etc.; and in the garbage treatment process at the composting, landfilling, incineration, and transfer.
Exhaust gas composition of the foundry industry
After the operation of the foundry, the main environmental pollution factors are industrial dust and casting fumes generated from the processes of modeling, core making, sand mixing, sand treatment, electric furnace melting, casting, vibration sand dropping, shot blasting and cleaning, etc. In addition, a small amount of organic waste gas is generated in the process of paint dipping and the coating process of sand coatings. The organic waste gas produced in casting production is low in concentration, large in volume and discontinuous.
Injection molding industry exhaust gas composition
1. Rubber injection molding: Rubber injection molding is a production method in which the rubber material is injected directly from the barrel into the model for vulcanization.
2. Plastic injection molding: plastic injection molding is a method of plastic products, the use of molten plastic pressure into the plastic products mold, cooling and molding to get want all kinds of plastic parts. There are mechanical injection molding machines specifically designed for injection molding. Currently the most commonly used plastic is polystyrene.
The injection molding process of plastic parts mainly consists of 4 stages such as filling – pressure holding – cooling – demolding. The injection molding machine produces a large amount of organic waste gas during the injection heating process, such as styrene, toluene, non-methane total hydrocarbons, etc. Unorganized emission of styrene, A and other organic waste gas, etc. will cause serious pollution to the environment. Its main components are dust particles, non-methane total hydrocarbons and other harmful substances.
Exhaust gas composition of asphalt industry
Bitumen can be categorized into three main types: coal coke bitumen, petroleum bitumen and natural bitumen.
In a variety of asphalt-based waterproofing materials in the production process, the need for asphalt heating, transportation and made to meet a variety of process requirements of asphalt mixture for production use. In this process, will produce a large number of asphalt fumes. Fumes contain a variety of organic matter, including carbon cyclic hydrocarbons, cyclic hydrocarbon derivatives and other compounds.
Composition of exhaust gases from the welding industry
Welding exhaust includes welding fume and welding smoke, of which the main ones are ozone, nitrogen oxides, carbon monoxide and hydrogen fluoride.
Welding fumes, also known as welding fumes, are toxic substances that are often produced during welding operations. For example: acetaldehyde, rosin acid, isocyanates, nitrogen oxides, sulfides, hydrocarbons and so on. Welding fume is a very complex substance, in the fume has been found in the elements of up to 20 kinds of more than the largest content of Fe, Ca, Na, etc., followed by Si, Al, Mn, Ti, Cu and so on. The main harmful substances in welding fume are Fe2O3, SiO2, MnO, HF, etc., of which the most abundant is Fe2O3, which generally accounts for 35.56% of the total amount of fume, followed by SiO2, which accounts for 10-20%, and MnO, which accounts for about 5-20%.
Composition of exhaust gases from the printing industry
Printing is to transfer ink to the surface of paper, fabrics, plastics, leather and other materials by making plates, applying ink, pressurizing and other processes to the original manuscripts of text, drawings, photographs, anti-counterfeiting and other materials.
The main printing methods are: offset printing, flexographic printing, screen printing, gravure printing, etc., regardless of which printing method, the exhaust gas composition is mainly generated by the ink solvent exhaust, benzene, toluene, ethyl acetate, butyl acetate, 200 solvent oil, ethanol, butanol and so on. The ink used mainly contains color, resin, solvents, auxiliaries, etc., the generation of exhaust gas is mainly in the ink and drying, compounding process, volatile organic solvents is the main source of exhaust gas pollution. Water-based ink with water (45% ~ 50%) as a solvent, VOC content is low, little pollution to the environment. Oil-based ink to organic solvents (toluene, xylene, industrial alcohol, etc.) as a solvent, solvent volatilization caused by air pollution.
Pharmaceutical industry exhaust composition
Pharmaceutical process is divided into: chemical pharmaceutical process, biotechnology pharmaceutical process, traditional Chinese medicine pharmaceutical process, preparation process. In the production process, pharmaceutical companies will use a number of organic solvents with low solubility and good volatility (e.g., DMF, benzene, organic amines, ethyl acetate, methylene chloride, acetone, methanol, ethanol, butanone, ethyl ether, ethylene chloride, acetic acid, chloroform, etc.). Such solvents are likely to evaporate with the production process and lead to VOCs pollution, VOCs emissions mainly occur in the feeding, reaction, solvent recovery, filtration, centrifugation, drying, discharging and other operating units.
The characteristics of solvent emissions are mainly related to the characteristics of the pharmaceutical and chemical production process, as shown in the following:
1) Many emission points, large emissions, serious disorganized emissions. Pharmaceutical and chemical products, low yield, solvent consumption, almost every production equipment is a solvent exhaust emission points, each enterprise has dozens, or even hundreds of solvent exhaust emission points, and most of the solvent exhaust low-altitude disorganized emissions, solvent exhaust at the plant boundary concentration is high.
2) Intermittent emissions. The reaction process is basically an intermittent reaction, and the solvent exhaust is also emitted intermittently.
3) Emission instability. The composition of solvent exhaust gas is complex, the type and concentration of pollutants vary greatly, and the same set of devices may emit pollutants of different natures at different times.
4) Solvent exhaust has a wide range of influence. Most of the VOCs in solvent waste gas have malodorous nature, low olfactory domain value, easy to spread, and wide range of influence.
Composition of exhaust gases from electronic factories
Organic waste gas in the electronics industry causes environmental pollution is mainly generated in the chip, circuit board cleaning, glue, glue, etching, developing and other processes. Large-scale production line exhaust gas is generally composed of benzene, toluene, xylene, non-methane hydrocarbons and other organic gases, while there will be a small amount of high-temperature drying exhaust gas needs to be treated together.
