Application of Bag Dust Collector
With the development of bag dust removal technology and environmental protection requirements, the application range of bag filter is more and more widely. At present, bag filter can be used to treat high temperature, high humidity, bond, explosion and abrasive flue gas , Or even ultrafine dust-containing air.
1. High temperature, high humidity gas Various industrial furnaces, dryers and other flue gases are high-temperature flue gas, most of them also contain large amounts of water and sulfur oxide gas. The bag filter can deal with the flue gas with the temperature below 300 ℃. If the temperature exceeds 300 ℃, the flue gas should be pre-cooled. In special cases, the metal fiber filter can be used to treat 450 ~ 550 ℃ high temperature flue gas directly. With the bag filter treatment of steam boilers, cement kilns, metallurgical furnaces, incinerators and other high-temperature furnace flue gas, at home and abroad increasingly common. Although the bag filter by the filter temperature performance, but by the appropriate treatment of the system of flue gas, has been able to deal with the temperature of up to 1200 ~ 1400 ℃ high temperature flue gas.
2. Adhesive dust adhesion Dust in the filter bag surface is easy to compact, bag filter can be absorbed by the role of adhesive dust to deal with, that is, in the system into the appropriate amount of porous pipe powder, the use of powder to Adsorption of adhesive dust, and then by the bag filter for purification. Such as refractory plant with dolomite powder adsorption purification of asphalt smoke, aluminum plant with alumina adsorption of asphalt and hydrogen peroxide, road company asphalt concrete plant with limestone powder adsorption of asphalt smoke, the adsorption efficiency of up to 92 ~ 99%.
3. Explosive dust Explosive dust must also have the following three conditions will explode: ⑴ flammable substances in the flue gas in the appropriate concentration exists; ⑵ sufficient oxygen and oxidants; ⑶ have a fire source. Therefore, the purification of such gases should be taken to undermine the above three conditions or a condition of the measures taken. Simply control the ingredients that eliminate the fire; eliminate static electricity, equipment grounding; monitoring explosion, fire and explosion.
Corrosive gas In the flue gas purification system, the bag filter has a corrosive effect of two kinds of gas and dust media, such as coal, heavy fuel oil due to sulfur molecules formed by the presence of sulfuric acid gas, or water Will produce a variety of salt dust. At this point, in the application of bag filter should take the following anti-corrosion measures: As the flue gas cleaning in the corrosion phenomenon occurs in the flue gas temperature below the acid dew point occurred, and this should ensure that the system flue gas dew point Temperature above the run. In the choice of media, should be corrosive material characteristics of flue gas, using the appropriate filter, the corrosion of serious and demanding purification systems, such as pharmaceuticals, food, carbon black production industries, the importance of bag filter Parts should be made of stainless steel or brushing anti-corrosion coating treatment.
5 grinding pecking dust in the treatment of alumina, silica, sintering and other pecked dust, due to coarse particles in the dust and air flow in the bag filter movement speed is too high, resulting in the filter bag and the shell produced In order to reduce the amount of coarse dust in the flue gas and reduce the flow rate of the dust-laden gas, we should take appropriate measures, such as setting the pre-dust removal device before the flue gas enters the bag filter, Strict control of the bag inlet flow rate, easy to wear grinding at the entrance of wear-resistant materials. 9, the cement industry, the application of bag filter The cement industry is a major pillar industry in China, for China's construction industry has made great contributions. But its dust emissions on the environment caused by pollution is particularly serious, if the dust is not to be treated, the total dust emissions during the cement production process will exceed 5% of the total output (calculated according to the production of cement clinker), the loss of dust are finished Cement and various production processes of intermediate products, its economic losses are considerable. Circular of the State Environmental Protection Administration on November 4, 1998, Circular on Printing and Distributing the Work Plan for Achieving the Standardization of Environmental Functional Areas of Key Cities for Emission of Industrial Pollution Sources and Environmental Protection in 2000 issued by Circular  No. 366 of the State Environmental Protection Administration of the People's Republic of China The pollutants from the pollution sources meet the national or local discharge standards; the environmental air and surface water environment of municipalities and provincial capitals, special economic zones, coastal open cities and key tourist cities shall meet the quality standards stipulated by the State "Make the cement industry this industrial enterprises pollution must be made a series of effective measures to effectively control their dust pollution to meet the stringent requirements of the current environmental protection. China's cement industry to the atmosphere each year emissions of dust, dust in more than 10 million tons, becoming China's large dust pollution; other such as: carbon dioxide, sulfur dioxide, nitrogen oxides, fluoride pollution also occupy a considerable proportion. Cement production process can be simply divided into raw material preparation, firing and cement grinding three main processes. In the production must deal with a large number of powder and high temperature calcination; at room temperature dust gas and high temperature dust gas is the cement industry's most important pollutants, but also the cement industry resources can not be a good factor in one of the factors. Cement production process of electrical equipment and machinery and equipment due to the presence of dust, making life significantly shorter, can not give full play to effectiveness. In recent years, the state in the cement industry has invested a lot of financial and material management of dust, but still less than expected results, one important reason is that technology is still lagging behind, less effective; cement industry in the application of a large number of bag dust removal equipment, Selection and application, there are still many unreasonable factors. As a kind of efficient dust removal equipment, bag filter has been widely used in the production of cement industry. With the continuous progress of cement production technology, many production processes can only be achieved with bag filter to meet the needs of production Of the emissions requirements; that is, in the cement industry is now the bag filter is not only environmentally friendly equipment, but essential for the production of the equipment.
(A), the preparation of raw materials
1. limestone crushing, transportation and reserves limestone is the main raw material for cement production, limestone after entering the factory to go through several levels of crushing, through reserves and then enter the next process, in the process there are many dust spots, the original use of more Is the high-pressure tube ESP, the use of results are relatively poor, in recent years to switch to bag filter has improved, but because of the selection of dust, clean, unloading ash parameters to determine the selection of media, etc. There are still many problems; therefore, much remains to be done.
2. raw mill dust dust dust mill dust mill has been the difficulty of cement, but until now has not caused enough attention; raw dust mill dust is difficult to part of the dust containing high humidity, exhaust gas In the wet content of the plant with the process conditions are different and have a greater difference. Many plants do not have drying equipment, high moisture in the rainy season raw materials, this part of the moisture to the raw material dust grinding difficult, no matter what kind of dust removal equipment must consider this issue; so raw material bag mill dust The anti-condensation problem must be considered.
3. Coal mill system Bag filter Most of the rotary kiln of cement plant is coal-fueled, coal mill dust removal system optional special design of the bag filter; This is because the pulverized coal is a flammable gas Explosion gas, so coal mill with bag filter must be equipped with explosion-proof, safe pressure relief measures, the filter bag must be anti-static filter.
4. Drying of raw materials Drying method of raw materials used in cement plants, in addition to natural drying, there are two: one is in the grinding process at the same time drying, drying process and the grinding process in the same Equipment; the other is to set up a separate drying equipment, and drying equipment, exhaust emissions from the main dust source of cement plants, especially the clay drying system. Domestic use of specialized drying equipment is mainly, rotary dryer, commonly used specifications are: ф1.5X12m; ф1.8X14m; ф2.2X14m; ф2.4X18m; ф3.0X20m several. It is characterized by high moisture content, moisture content in the exhaust gas is generally more than 15%, the dew point temperature up to 55 ℃ or more; dust concentration of up to 50g / Nm3. Therefore, the LFEF series bag filter used in the dust removal of the dryer adopts many anti-condensation measures, such as high-temperature anti-condensation filtering material, main body anti-corrosion, thermal insulation measures and automatic temperature detection and adjustment measures.
(B), the firing system dust
1. Flue gas kiln dust is a major means of production of cement, the main pollutants for high temperature dust gas; flue gas contains a large number of dust concentration of 30 ~ 100g / m3; due to the high chimney, flue gas volume, high concentration , Drifting far, such as bad governance on a few kilometers or even tens of kilometers of environmental pollution are great. The maximum allowable temperature of the bag filter for rotary kiln kiln is 280 ℃. Therefore, the bag filter is equipped with temperature control facilities, such as waste heat boiler, multi-tube cooler, humidification tower, etc .; When the temperature of the flue gas is normal, the cold air valve is fully closed; if the kiln is abnormal, when the flue gas temperature is too high, the cold air valve will be opened, so that the flue gas temperature will be maintained at the same time. Below 280 ° C.
2. Shaft kiln dust Our country's cement production of more than 80% from shaft kiln; as the plant raw materials, ingredients and operating habits of different shaft kiln smoke dust concentration, moisture content, exhaust temperature and other working conditions change greatly ; So shaft kiln dust as the cement industry over the years the problem, until the nineties of last century from the technical to be resolved. Shaft kiln calcination method can be divided into open fire, shallow dark fire and deep dark fire; kiln surface wet layer thickness of a direct impact on vertical kiln flue gas temperature and dust concentration. Deep dark fire operation, the wet layer thickness of up to 1000mm above the smoke through the wet layer of the endothermic, filtration, the temperature is very low, generally below 50 ℃; then the dust concentration of flue gas is low, Usually in the 5g / m3 or so; when the fire operation, the exhaust temperature can reach 250 ℃, dust concentration will be more than 20g / m3, if the use of shale and other poor plasticity raw material ingredients, flue gas dust concentration will be higher ; Dark fire operation is between the two. Of course, the working conditions of flue gas and kiln door at the leakage of cold air volume, when the kiln door open, low temperature, deep dark fire operation, the kiln door can not open. Under normal circumstances, the flue gas dew point temperature is about 40 ℃ or so. In view of the above situation, it is required to use on the shaft kiln bag filter must meet the above-mentioned wide range of fluctuations in conditions; LFEF series shaft kiln dedicated bag filter is designed to meet this condition; has been promoting the use of more than 500 Sets;?
(C), made of dust system
1. Cement mill dust removal Technically speaking, the cement mill dust removal is the most easy to solve the cement industry, but the process point of view, with the continuous progress of technology, the use of high-class separator, cement mill discharge concentration The higher the bag, sometimes more than 1000g / m3, when the bag filter is not only the dust removal equipment but a part of the host equipment; Therefore, the cement mill dust collector and dust removal system must be designed to achieve a dust System directly dealing with high concentrations of dust-containing exhaust gas capacity. We promote the use of PPW gas box pulse bag filter can meet this requirement in the cement industry is also the most used.
2. Cement packaging system dust dust packaging system has several dust spots, the original single-use dust collector, the use of results is very bad, in recent years we have transformed a number of cement plant packaging system dust, we use centralized dust removal program, a few A dust point combined with a bag filter, are made of a good use of results.