空气分级与空气重介流化床分选联合工艺研究

Combined Process of Air Classification and Coal Cleaning with Air-Solid Fluidized bed

分析了固体颗粒在气 -固流化床中的受力情况和运动方程 ,通过理论分析和实验得出了空气重介流化床分选入料的适宜粒级 .讨论了空气重介流化床分选对入料粒度上下限的控制方法和存在问题 ,介绍了潮湿原煤空气分级新方法 .试验表明 ,空气分级对潮湿原煤颗粒表面的煤粉有“清洗”作用 ,脱粉效果好 ,粗粒产物中含粉率仅为 0 .2 % ,这对控制入料粉量、稳定流化床密度和减少介质净化非常有利 ;空气分级还有分选作用 ,就试验煤种而言 ,其细粒级产物灰分比原煤中同粒级灰分降低 1 .7个百分点 ,比原煤灰分降低 7.5个百分点 .空气分级和空气重介流化床分选结合 ,可优化干法选煤工艺、降低工程投资和分选成本 5 0 %以上 .

A force balance or motion equation of a particle in air-solid fluidized bed was set up and analyzed. An appropriate size fraction which could be effectively separated in air-solid fluidized bed was determined by theoretical analysis and tests. The problems in controlling upper size and lower size of feed into an air-solid fluidized bed were discussed, and then an air classification technology of moist raw coal was introduced. Pilot Test results show that 1) the air flow has a good 'dust-washing' effect on the surfaces of coarse coal particles in air classification, and nearly all coal dusts smaller than 1 mm were washed off from the coarse particles by air flow. As a result, the coal dust content is as low as 0.2% in the coarse particle product. This is very favorable for stabilizing the fluidized bed density and reducing the burden of medium purification; 2) air classification has a 'clean' effect on fines product. As far as the treated coal is concerned, the ash of fines product obtained by air classification is 1.7% lower than the ash of the same size fraction in feed, and 7.5% less than the feed ash because of the density difference between the clean and the waste. A combined process of air classification and coal cleaning with air-solid fluidized bed is put forward, which can optimize coal dry cleaning process, and then reduce the construction and operation costs by more than 50%.