The application of dedusting technology of dryer exhaust gas

It is difficult for dust removal technology that the dryer exhaust gas has large air volume, high dust concentration, large moisture content, high dew point, easy condensation, high emission point and wide pollution range The exhaust gas at the end of the dryer is related to the process conditions of each plant Some enterprises use it to dry many materials, which has great production changes, frequent start-up and shutdown, and large fluctuation range Moreover, coal is used as the heat source of drying, the sulfur oxide in the exhaust gas has corrosive effect on the metal structure parts, which brings certain difficulties to the selection of the dust remover Cyclonic dust removal technology cyclonic dust removal technology has the characteristics of low equipment cost, high temperature gas treatment, easy operation, suitable for gas with high dust concentration Its working principle is that under the action of the fan, the dust laden air flow enters the dust collector volute from the inlet at a higher speed along the tangent direction, and makes a spiral rotation movement from top to bottom Under the action of centrifugal force, the dust particles are thrown to the outer wall, and rotate downward along the wall surface With the contraction of the cone, they turn to the axis, return under the resistance of the lower part, and rotate through the core tube row from bottom to top along the axis Out The dust particles on the outer wall fall into the ash hopper along the wall driven by gravity and downward moving airflow, so as to achieve the purpose of dust removal Because the cyclone dust collector relies on the inertia separation of dust particles, the dust removal efficiency is directly proportional to the particle size, and the large particle size has good dust removal effect; the small particle size has poor dust removal effect Generally, the dust removal efficiency is 70% - 90% when the dust is more than 20 microns Bag filter technology is generally recognized for its stability, simple maintenance and reliable operation It can remove up to 99% of the dust contained in 0.1 μ m particles The bag filter used for the dust removal of dryer exhaust gas does not need to consider the problem that the emission concentration exceeds the standard The anti condensation glass fiber bag dust remover of dryer is the ideal dust removal and purification equipment at present The equipment adopts microcomputer control, chamber back blowing, timing ash cleaning, temperature detection display, over temperature alarm device, cw300-fca anti condensation glass fiber filter bag, which can effectively prevent the filter bag from condensation and will not burn the filter bag Hebei Taihang Group Co., Ltd changed the two-stage dedusting process into one-stage lfef7 × 358-hsy / h anti condensation bag deduster with a diameter of 3 × 24m According to the determination of the environmental protection department, the waste gas volume is 42621 standard cubic meters per hour, the imported dust concentration is 69620 mg per standard cubic meter, and the outlet dust concentration is 147 mg per standard cubic meter, meeting the national emission standard Not only the output is increased, but also the dry materials are recovered The annual economic benefit is more than 700000 yuan, and the obvious social benefit is obtained However, the bag filter has the disadvantages of large floor area and high investment With the development of the membrane covering technology, this disadvantage will be overcome and used more widely High voltage electrostatic precipitator technology The technology of high voltage electrostatic precipitator is to change 50 Hz, 220 V alternating current into 100 kW direct current and add it to the corona electrode (cathode) to form an uneven high voltage electric field, so that a large number of negative ions and electrons are generated by gas ionization, and the gas dust entering the electric field is charged Under the action of the electric field force, the charged dust tends to the opposite electrode Generally, the anode is the dust collector, which falls into the ash by vibration The hopper is discharged to complete the purification and dust removal process High voltage electrostatic precipitator with low resistance can be widely used in dust pollution occasions of building materials, metallurgy, chemical industry and other industries It has high dust concentration, and the dust removal effect is more obvious for 0.01 μ m fine or high specific resistance dust The series of products meet the requirements of drying equipment with different air volume, match flexibly, and are suitable for dust treatment of dryer exhaust gas characteristics Wet dedusting technology The wet dedusting technology is that the dust containing gas is sent to the lower part of the dedusting tower by the induced draft fan through the air duct Due to the larger cross section, the flow rate is reduced, and the coarse particle dust first settles in the air stream, the finer dust rises with the air stream, and the water droplets and the dust air stream move reversely under the spray, and the self weight of the dust is continuously increased by the wet moistening Under the effect of gravity, the dust is reduced to slurry water by overcoming the lifting force of the air stream, Enter the sedimentation tank through the lower pipeline to achieve the purpose of dust removal Generally, mud water is transformed into clean water through 2-3-stage circulating sedimentation and pumped into the dedusting tower for recycling without secondary pollution The positive pressure operation of the dust removal technology is generally used for drying clay, drying a variety of materials (raw materials), recycling materials are easy to mix and can not be used, and the wind blade is greatly worn Suzhou cement plant uses wet dedusting technology on a clay dryer with a diameter of 2.2 × 12m The emission concentration is 132 mg per standard cubic meter, which meets the national emission standard The sedimentation tank shall be cleaned once a year, and the wet soil shall be dried and put into storage as production raw materials The dust collection system has high efficiency, low resistance, no secondary pollution, flexible process, reliable operation, low power consumption, low investment, no condensation, strong adaptability, and good economic and social benefits Gravity sedimentation + high voltage electrostatic precipitator technology The dust removal process is composed of a settling chamber and high-voltage static electricity The dust containing waste gas is sent to the settling chamber at high speed by the induced draft fan through the air duct and collides with the wall The air flow direction changes, so that the wind speed decreases rapidly The particle dust settles After being discharged by the conveying equipment, the fine dust enters the electric field of the high-voltage electrostatic precipitator along with the air flow Under the continuous bombardment of ions, the dust is charged and flies to the dust collecting pole to be collected and then discharged The purified gas is discharged into the atmosphere through the air pipe In the two-stage dedusting process, the primary settling chamber collects large particles of dust above 40 μ m, reduces the dust concentration of the gas, improves the dedusting efficiency of the high-voltage electrostatic precipitator, and reduces the investment effectively In the dust removal process of the clay dryer with a diameter of 2.2 × 12m in Lanxi cement plant, Zhejiang Province, the dust containing waste gas is sent from the tail cover of the dryer to the square settling chamber made of steel plate by the induced draft fan through the air duct, and then enters the high-voltage electrostatic precipitator after the waste gas settles, and is discharged into the atmosphere after purification The induced draft fan and settling chamber are installed indoors, and the electrostatic precipitator is installed outdoors The dedusting system operates normally and has been used for many years without condensation According to the measurement of the environmental protection department, the emission concentration is 48 mg per standard cubic meter, which is lower than the national emission standard Cyclone + high voltage electrostatic precipitator technology The dedusting technology is that the dust containing waste gas of the dryer enters the front cyclone deduster by the air pipe for pre dedusting, the dust is discharged by the ash hopper through the ash discharge equipment, the dust concentration of the air flow is reduced, and then enters the secondary dedusting of the high-pressure electrostatic precipitator, and the purified gas is discharged into the air by the fan, so that the dedusting efficiency is improved, the process is flexible, safe and reliable The application of dust removal technology of dryer exhaust gas not only protects the environment and reduces the labor intensity, but also improves the output of the unit time and reduces the expenditure of pollution discharge fee The recovered dust is a good raw material for cement production, with significant economic, social and environmental benefits The article is the author's independent point of view, which does not mean Alibaba takes the position of chamber of Commerce friends Reprint of this article must be approved by the author, with the source and link.