Low speed large capacity centrifuge centrifuge used in | coal preparation technology research

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Low speed large capacity centrifuge to understand China existing coal preparation plant, more than 90% is the wet separation process. Along with the coal market competition is becoming increasingly fierce, the user of coal commodity quality requirements more and more severe. Coal commodity moisture is an important goal, the domestic coking coal demand for water can not be higher than 13%, export the moisture of cleaned coal demand does not exceed 8%. The moisture of cleaned coal is high, to the production and use of bring a series of as effect, formed many invalid shipping, add delivery cost, waste transport resources. The coking coal, high moisture, will add heat consumption, extend the coking time of coke oven coke decreased, yield, shortening life. Other, coal preparation plant production, coal moisture content is too high also makes the delivery belt slipping. Low speed large capacity centrifuge found vertical scraping centrifuge for powder coal dewatering is primary, primary dewatering equipment for coal preparation plant. It selects the filtering method to the processing of water material added in the rotating conical sieve surface, because of the centrifugal force, the solid close to the screen rotation with the rotor and a big endian discharge, liquid through the void and sieve seam material thrown out. The following detailed planning and production practice analysis about the effects of the main factors of centrifuge dewatering.
Influence factors of dehydration
The separation factor
Low speed large capacity centrifuge according to vertical scraper centrifuge processing material properties and process requirements, vertical scraping centrifuge separation factor can be selected is not the same, the separation factor is the ratio of material by centrifugal acceleration and acceleration of gravity G. The separation factor is that a primary goal of vertical scraping centrifuge separation ability, is one of the important symbol of vertical scraping centrifuge function. The larger the value of centrifugal force, the material is bigger, better separation effect. If you add a sieve basket centrifuge speed and diameter, the separation factor increases, resulting in improved centrifuge dewatering effect in a certain range. But because of excessive speed accelerated sieve sieve basket basket wear, one will also drop other wearing parts using life. Low speed large capacity centrifuge to understand other basket diameter is too large, the rotating part is corresponding to the diameter increases, the processing difficulty is big, safe and reliability of falling equipment. Therefore must be controlled in a certain scale separation factor. The separation factor of vertical scraper discharge centrifuge is usually in the 120~200 scale selection of half cone angle of the sieve basket half cone angle size directly affects the motion state of materials in the residence time on the surface and the screen, and then affect the centrifuge dehydration. The material in the sieve surface of the sliding speed not only with the relevant materials, and also with the location of the radius of gyration of the relevant. The radius of gyration is larger, the smaller the sliding speed; radius of gyration of the smaller, the greater the sliding velocity. Therefore, in the material in the sieve basket sliding velocity by the small end to end gradually diminishing. Low speed large capacity centrifuge with value increasing, the sieve basket into the discharge end diameter difference is bigger, the greater the difference between the material sliding speed. After all, if the cone angle is too large, because the difference before and after the material sieve basket sliding velocity is too large, resulting in the discharge end of the material layer thickening, forming material along the screen basket length distribution is not uniform, the centrifuge dewatering function variation.
Sieve basket sieve surface cracks
Low speed large capacity centrifuge basket is found working surface filtration centrifuge dewatering, screen plays a vital role in vertical scraping centrifuge. Crevice sieve surface gap is the main factor of influence of dehydration power, usually the gap is 0.5 ~ 0.35 mm, slotted screen is bigger, better and dehydration, dehydration is poor. Low speed large capacity centrifuge recommended in the precondition of ensuring the commodity dehydration power, reduce the screen slots can reduce the screen strip wear, and cut the solid content in centrifugal liquid.
Sieve basket and blade gap between cooperation
Fixed scraper cone is made of cast steel. Along rotor cone outer wall 8 (type TEL) spiral rib edge. The gap size between the sieve basket and blade of the rotor, has a great influence on the effect of centrifuge. Cooperation in space is small, the sieve surface direct coal layer is thin, easy to pass water, dehydration, together, sieve seam is not easy to be blocked, centrifuge load is light, small power consumption. The cooperation of the gap is too large, the screen surface will not fall is adhered with a layer of coal seam, make the coal flow only along the seam sliding, so that not only add mobile resistance, and in the same amount of processing under, the centrifuge loads add, power consumption is increased, and the coal particle representation also tend to more serious destruction. Sift together the surface adhesion of coal seam is thick, flow resistance through addition, effect of dehydration. Visible, screen basket and cooperation between scraper gap size is one of the primary reasons for centrifuge dewatering effect, is one of the important contents of adjustment. Low speed large capacity centrifuge according to demand, cooperation gap should be 2 - 1 mill. Such as voids due to wear and increase, should be adjusted in time. With the adjustment method is 1 groups of adjusting pad in the upper part of the spindle shaft shoulder, each shim thickness is 1 mm, when a gasket from the upper to lower that shift spiral scraper rotor all progress, and the gap between the scraper and the screen basket also reduced 0.36 mm, when all the gasket in full to the lower part later, it has not used scraper, should re replacement.

Blade helix angle
Because the sieve basket and blade rotor rolling to do with constant velocity, material is forced to press the scraper dehydration helix mobile, mobile coal flow and sieve seam oblique, the width of the slit larger screen useful. If the coal flow trajectories and the included angle between the sieve (i.e. blade spiral angle), B screen seam width, sieve seam width is useful for the B=b / sin / 3 (4) of helix angle and blade pitch on, pitch is small, Lu angle is small. Based on the formula one, when the screen slot width B as the set value, the pitch was smaller, bigger, more easily through the water, but the amount of coal with the centrifugal fluid loss is added, the grain size. At the same time, discharging speed slows down, and dehydration time extending, low speed large capacity centrifuge to understand its dehydration, processing can also under dynamic impact. On the contrary, the greater the blade pitch, coal flow along the spiral movement speed faster, higher processing to centrifuge. The shorter the time of coal dewatering, sieve seam width decreases, dehydration resistance added, dehydration will become bad. Loss of processing capacity, so consider the factors of centrifuge product moisture, centrifugal liquid coal, spiral angle accurately pick scraper. The current planning value / 3=45 ~ 60.
Feeding method and the distribution plate
People the material uniformly, stop the bulk materials and iron into the basket. If the feed is not uniform, on and off, suddenly more and less, will greatly influence the material dehydration, together may make the centrifuge oscillation. Other changes to the single people feed mode, implement human mixed material, so also can progress of centrifuge dehydration. The distribution plate and a material guide plate, increasing the distribution plate top angle, to decrease the feeding axial velocity, residence time and extension of material in dewatering section, progress of dehydration, the amount of processing equipment down together. In addition, it was found that the size of low speed large capacity centrifuge commodity water and people material slime scraper centrifuge components are closely related, in the feed concentration under the same conditions, people guess <80 intention fine mud content in 10% power (maximum cannot surpass 15%), commercial water can be controlled at around 12%, followed by <80 fine mud content progress, commercial water increases greatly. Therefore, manipulating people guess <80 intention fine clay content, moisture is the key control of goods.
Technical parameters of centrifuge is based on demand and economic principle of separation process, summed up the balance of various elements and selected. Thinking from the machine inductive function, use low speed, small basket half cone angle and a large screw lead to low speed difference and low charging axial velocity, feeding a pre rotation to ensure dehydration, is the key to optimal planning of vertical scraper discharge centrifuge.