[China Glass Network] I. Overview Online Low-E glass is a new type of energy-saving green building materials with good energy-saving effects. The promotion and application of such products will contribute to energy-saving and emission reduction work and promote low-carbon economy. This paper will analyze the main exhaust gas pollution sources and control measures of the online Low-E glass project. Second, the main source of waste gas pollutants in the production of Low-E glass, there are batching, melting and forming sections. The ingredients and molding are physical processes, and the pollution generated is mainly dusty exhaust gas. Melting mainly melts and decomposes the material through the combustion of the fuel, and the main pollutants generated are soot, SO2, NOx and the like. The main pollution conditions are: (1) Dust: The raw materials for glass production are mainly granular and powdery, which are scattered during storage, transportation and mixing. (2) Soot: The soot in glass production mainly comes from the following aspects: First, the raw materials in the feeding are brought into the flue gas of the melting furnace; second, the volatile substances in the melting furnace are volatilized at high temperature and then condensed to form soot; It is the smoke generated by the combustion of the fuel. Usually, the initial concentration of soot is about 200-400 mg/m3. (3) SO2: First, the combustion of sulfur-containing fuel in the melting; second, the decomposition of the mirabilite in the raw material. The initial concentration of SO2 using natural gas as fuel is 300-1000 mg/m3. (4) NOx: mainly produced by combustion of combustion air and pyrolysis of a small amount of nitrate in the raw material. N2 and O2 in the air generate a large amount of NOx at a high temperature of the furnace at a temperature of 1650-2000 °C. In addition, the nitrate in the raw material is also easily decomposed into a small amount of NOx. Therefore, a large amount of NOx is generated in the furnace flue gas, and the concentration is usually as high as 2000 mg/m3. (5) HCl: The raw material and cullet contain chlorine, and a small amount of HCl is formed during combustion. The coating process during the coating process decomposes to produce HCl. (6) Fluoride: Glass usually does not use fluorite as a raw material, and its emission is mainly derived from the F-containing impurities in the raw material and the decomposition of the coating agent in the coating process. (7) Others: There is an unorganized emission of ammonia in the process of liquid ammonia decomposition. The coating process emits organic waste gas, tin and its compounds. Embroidered Flannel Coral Blanket Winter Embroidered Flannel Blanket,Double Layer Coral Blanket,Children Velveteen Coral Fleece,Kids Flannel Heavy Embroidered Coral Shaoxing Fangzhuo Textile Co.,Ltd , https://www.printblanket.com
Third, the main exhaust gas pollutants control technology 1. Dust dust treatment combined with production characteristics, take the decentralized or centralized management, the recycling of available dust back to production. Under normal circumstances, the same material, the same production process, dust collection points are not far apart, when the use time is basically the same, try to set up a centralized dust removal system. In other cases, decentralized treatment can be used to achieve greater recycling of materials. The key equipment for dust removal is various types of dust collectors, mainly including bag, static electricity, cyclone, hydraulic and other types of dust collectors. The initial concentration of dust in glass production is relatively low, and two-stage dust removal is less used. Usually, cyclone separator is not used as pretreatment; hydraulic precipitator has low efficiency, large fluctuation, secondary pollution of waste water, and less use; electric dust removal is better than bag dust removal. The investment is large, the dust removal effect is relatively low, and it is rarely used. 2. The main pollutants controlled by flue gas in the flue gas furnace are soot, SO2 and NOx. At present, the glass projects are all considering the construction of denitration equipment, denitration, desulfurization and dust removal. (1) NOxNOx control measures can be divided into source control and end control. Source control measures to prevent or reduce NOx formation for the mechanism of NOx production. The main measures include low-nitrogen combustion technology and pure oxygen combustion-supporting technology. Pure oxygen combustion is the use of oxygen with a purity greater than 90% in the furnace instead of air. It has the advantage of saving about 30% of fuel, increasing the output by about 25%, and greatly reducing the amount of soot and NOx. Depending on the purity of the supplied oxygen, the amount of NOx generated by pure oxygen combustion can be reduced by 70-90%, and the terminal NOx emission coefficient is 0.5-1.5 kg/t glass, which can reduce 2/3 NOx compared with air-assisted combustion. At present, pure oxygen combustion-supporting technology has not been widely promoted, but in general, this technology is a development direction for the glass industry to achieve cleaner production. The end control is to reduce the NOx generated in the combustion process, and reduce the NOx emissions in the exhaust gas through certain removal techniques. The main measures include: SCR, SNCR, 3R, wet reduction absorption method. With SCR denitration technology, the efficiency is 70-80%. The NOx after treatment reached 700 mg/m3 or less.
(2) The dust particle size of soot and SO2 melting furnace is in the range of 0.1-0.5 μm, and the concentration is 200 mg/m3. Dust collectors using the principles of inertia, centrifugation, gravity, etc. cannot effectively capture particles of particle size below 1 μm, and generally do not use such dust collectors. The precipitators that can be used are: wet, bag and electrostatic precipitators. For the control of SO2, according to the principle of desulfurization, it is divided into semi-dry method, dry method and wet method. According to different absorption agents, wet desulfurization is divided into magnesium method, sodium method, calcium method, ammonia method, etc. It has the advantages of relatively high desulfurization efficiency and absorbent utilization rate. The disadvantage is that the treatment system is complicated and there is secondary pollution of wastewater. The advantage of the semi-dry or dry desulfurization process is that the treatment system is simple and the investment is low, and the disadvantage is that the desulfurization efficiency and the utilization rate of the absorbent are relatively low. The main processes used for dust removal and desulfurization are as follows: The wet dust removal and desulfurization flue gas is in full contact with the washing water in the dust removal and desulfurization device. Under a series of complicated physical and chemical actions, the SO2 is fully absorbed by the washing water, and the particulate matter in the flue gas Aggregate sedimentation and taken away to achieve the purpose of dust removal and desulfurization. The purified exhaust gas is dehydrated in the device and discharged from the chimney. The washing water carrying the soot is discharged into the circulating sedimentation tank, and the precipitate is separated under the action of gravity, and the upper layer of water is adjusted to adjust the pH value and then reused. The advantages of wet dust removal and desulfurization are high efficiency, integration of desulfurization and dust removal, simple process equipment, and low investment and operating costs. Disadvantages are problems such as improper handling, corrosion, scaling, and secondary pollution of wastewater. Semi-dry method / dry desulfurization + electric dust removal, the process is characterized in that before the flue gas enters the electrostatic precipitator, a desulfurizing agent is sprayed into the humidity control tower to remove sulfur, and at the same time, the temperature is lowered, the flue gas humidity is increased, and the specific resistance of the soot is adjusted. After adjustment, it enters the subsequent electrostatic precipitator. After purification, the exhaust gas is transported by the fan to the chimney through the pipeline. The advantage of this technology is high dust removal efficiency and stable operation. The disadvantages are large energy consumption, poor sulfur removal effect and large one-time investment.
(3) The common scheme for comprehensive treatment of flue gas is to send the high-temperature flue gas discharged from the glass melting furnace to the waste heat boiler. After the heat recovery, the waste heat boiler is taken out at the flue gas temperature of 320-350 ° C and sent to the denitration system. The flue gas purified by denitration enters the waste heat boiler again to continue to recover the waste heat. When the temperature of the flue gas is lowered to about 180 ° C, the flue gas is taken out from the waste heat boiler and sent to the desulfurization dust remover for dust removal and desulfurization, and the flue gas is discharged after the purification. IV. Conclusion The exhaust gas treatment measures for the online Low-E glass project have been relatively mature. In specific engineering applications, the corresponding control measures should be reasonably selected according to the characteristics of the project to achieve greater economic and environmental benefits.