惰性粒子喷动流化床中冷冻融解氢氧化铝污泥干燥试验研究

Drying of frozen-thawed aluminum hydroxide sludge from aluminum producers in an inert particles spout-fluid bed

在125mm的惰性粒子喷动流化床内对冷冻融解的氢氧化铝污泥进行了低温干燥实验研究,考察了惰性粒子大小、污泥加料量与惰性粒子质量比、惰性粒子静床高与床径比、表观流化气速与喷动气速之比等因素对污泥湿含量随时间变化快慢的影响.结果表明,在实验研究的范围内,较适宜的工艺条件为:惰性粒子(玻璃珠)粒径为1.43mm,污泥加料量与惰性粒子质量比不大于0.5,惰性粒子床层的高径比为1.4,表观流化气速与喷动气速之比为1∶4.这是由惰性粒子喷动流化床的流动特性及粘性物料的干燥机理决定.

The drying characteristics of frozen-thawed aluminum hydroxide sludge (containing 65%～70% water) were investigated in a 125mm spout-fluid bed with inert particles using low temperature air as hot resource. Effects of inert particle diameter, mass ratio of sludge to inert particles, ratio of inert particles static bed height to bed diameter, ratio of superficial fluidizing velocity to spouting velocity on the moisture content change of sludge particles were examined. In the experimental range, the proper operating conditions were as follows: the diameter of inert particles was about 1.43mm; the ratio of inert particles static bed height to bed diameter was 1.4; the ratio of fluidizing velocity to spouting velocity was 1∶4; the mass ratio of sludge to inert particles was not greater than 0.5 to keep the bed in a spout flow regime. This conclusion attributed to the unique flow characteristics of spout-fluid beds with inert particles and drying mechanism of cohesive particles in this kind of beds.