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Abstract:The dryer has a large amount of exhaust air, high dust concentration, high moisture content, high dew point, easy condensation, high discharge point, and wide pollution range, which are the difficulties of dust removal technology. The exhaust gas at t…
The dryer has a large amount of exhaust air, high dust concentration, high moisture content, high dew point, easy condensation, high discharge point, and wide pollution range, which are the difficulties of dust removal technology. The exhaust gas at the tail of the dryer is related to the process conditions of various plants. Individual enterprises use them for drying multiple materials. The production changes are large, the frequency of startup and shutdown is frequent, and the range of fluctuation is large. Furthermore, coal is used as a drying heat source. Oxides have a corrosive effect on metal structural parts, which brings certain difficulties to the selection of dust collectors.
Cyclone dust removal technology
Cyclone dust removal technology has the characteristics of low equipment cost, can handle high-temperature gas, easy operation, and is suitable for gases with high dust concentration. Its working principle is that under the action of the fan, the dust-containing airflow enters the dust collector volute from the inlet at a high speed along the tangential direction, and spirally rotates from top to bottom. The dust particles are thrown away by the centrifugal force. It rotates outwards and downwards along the wall, turns to the center of the shaft as the cone shrinks, returns under the resistance of the lower part, and rotates spirally from bottom to top along the center of the shaft and discharges through the core tube. The dust particles on the outer wall are driven by gravity and the downward moving airflow, and fall into the ash hopper along the wall surface 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 proportional to the particle size, and the large particle size has a good dust removal effect; the small particle size, the dust removal effect is poor. Generally, it handles dust above 20 microns, and the dust removal efficiency is 70% to 90%. .
Bag dust removal technology
The bag dust collector is stable, efficient, simple to maintain, and reliable in operation. It is widely recognized that it has a dust removal efficiency of up to 99% for 0.1 micron dust-containing gas. The bag dust collector for the exhaust gas dust removal of the dryer does not need to consider the problem of excessive discharge concentration. The anti-condensation glass fiber bag dust collector of the dryer is an ideal dust removal and purification equipment at present. This equipment adopts microcomputer control, separate blowback in the room, regular dust cleaning, and is equipped with temperature detection display, over-temperature alarm device, CW300-FcA anti-condensation glass fiber filter bag, which can effectively prevent the filter bag from dew condensation and will not burn. Bad filter bag. Hebei Taihang Group Corporation slag dryer with a diameter of 3 × 24 meters changed the two-stage dust removal process to a first-stage LFEF7 × 358—HSY / H anti-condensation bag dust collector. The amount of exhaust gas was determined by the environmental protection department to be 42621 standard cubic meters per hour. The import dust concentration was 69620 mg per standard cubic meter, and the export dust concentration was 147 mg per standard cubic meter, which met the national emission standards. Not only increased the output, but also recycled the dry materials, the annual economic benefits reached more than 700,000 yuan, while receiving significant social benefits. However, the bag dust collector has the disadvantages of large area and high investment. With the development of filter bag coating technology, this disadvantage will be overcome and its use will be more widespread.
High-voltage electrostatic dust removal technology
High-voltage electrostatic dedusting technology converts 50 Hz, 220 volt AC power into more than 100 kW DC power and adds it to the corona electrode (cathode) to form an uneven high-voltage electric field, which ionizes the gas to generate a large number of negative ions and electrons, and charges the gas dust entering the electric field. Under the action of the electric field force, the charged dust tends to the opposite electrode. Generally, the anode is a dust collecting electrode, and it is discharged by the vibrating ash into the ash bucket to complete the purification and dust removal process. High-voltage electrostatic precipitator with high efficiency and low resistance can be widely used in dust pollution occasions in industries such as building materials, metallurgy and chemical industry. It handles high dust concentration, and has a more effective dust removal effect for 001 micron fine or high specific resistance dust. The series products meet different air volume drying equipment, and are flexible and suitable for dust treatment of the characteristics of the exhaust gas of the dryer.
Wet dust removal technology
The wet dust removal technology is that the dust-containing gas is sent by the induced fan to the lower part of the dust removal tower through the air duct. As the cross section becomes larger, the flow rate is reduced, and coarse particles of dust first settle in the air flow. The finer dust rises with the air flow and sprays water drops. Reverse movement with the dust airflow, the dust is continuously increased by the wet weight. Under the action of gravity, it overcomes the lift of the airflow and drops into muddy water. It enters the sedimentation tank through the lower pipe to achieve the purpose of dust removal. Mud water is generally precipitated into clear water through 2 to 3 levels of circulation, and pumped into the dust removal tower for recycling without causing secondary pollution. The positive pressure operation of the dust removal technology is generally used for drying of clay, drying of various materials (raw materials), the recycled materials are easy to mix and cannot be used, and the blades are abraded. Suzhou Cement Plant uses wet dust removal technology on a 2.2 × 12 meter diameter clay dryer, with an emission concentration of 132 milligrams per standard cubic meter, which meets national emission standards. The sedimentation tank is cleaned once a year, and the wet soil is stored in the warehouse as the raw material for production. The dust removal system has high dust collection 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 settlement + high-voltage electrostatic dust removal technology
The dust removal process is composed of a sedimentation chamber and high-voltage static electricity. The dust-containing exhaust gas is sent into the sedimentation chamber by a draft fan through a duct at high speed, and collides with the wall. The airflow direction changes, causing the wind speed to decrease rapidly, and the particulate dust is settled. As the airflow enters the high-voltage electrostatic precipitator's electric field, it is charged under the continuous bombardment of ions, and it is discharged to the dust collector after being collected, and the purified gas is discharged into the atmosphere through the air duct. In the two-stage dust removal process, the primary sedimentation chamber collects large particles of dust above 40 microns, which reduces the concentration of gas dust, which is helpful to improve the dust removal efficiency of the high-voltage electrostatic precipitator. The wind speed can be larger and the equipment can be smaller, which effectively reduces investment. The dust removal process of a clay dryer with a diameter of 22 × 12 meters in Zhejiang Lanxi Cement Plant. Dust-containing exhaust gas is sent from the dryer's tail cover to the square sedimentation chamber made of steel plate through an air duct through an air duct. The device is discharged into the atmosphere after purification. The induced draft fan and the sedimentation chamber are installed indoors, and the electrostatic precipitator is installed outdoors. The dust removal system operates normally, and has been used for many years without condensation. The environmental protection department has determined that the emission concentration is 48 mg per standard cubic meter, which is lower than the national emission standard.
Cyclone + high-voltage electrostatic dust removal technology
The dust removal technology is that the dust-containing exhaust gas of the dryer enters the front-stage high-efficiency cyclone dust collector for pre-dust. The purified gas is discharged into the atmosphere from the fan, which improves the dust removal efficiency, the process is flexible, and it is safe and reliable.
The application of dryer exhaust gas dust removal technology not only protects the environment and reduces labor intensity, but also increases the output per hour and reduces the expenditure on sewage charges. The recovered dust is a good raw material for cement production, and has significant economic benefits. Social and environmental benefits.