脱硅中液固循环流化床清洁传热

考察了铝土矿熟料溶出粗液脱硅加热过程中的结垢行为，采用有机-无机复合材质的惰性固体颗粒研究了循环流化床对脱硅加热过程中硅渣结垢的清除及防止性能.结果表明：硅渣结垢曲线为具有诱导期的渐近式曲线，硅渣结垢机理为结晶结垢和微颗粒沉积结垢混合机理；循环流化床不仅能有效防止硅渣结垢的形成，而且能完全清除已有的硅渣垢层，硅渣结垢的清除速率随操作流速及固体颗粒浓度的增大而增大；惰性固体颗粒的引入不影响硅渣结垢的机理.根据液固流化床的防垢机理建立了结垢模型，其预报值与实验值吻合较好.

CLEANING HEAT TRANSFER OF DESILICONIZATION HEAT EXCHANGER WITH LIQUID-SOLID FLUIDIZED BED

To solve Scaling problem, the scale formation and cleaning/prevention of desiliconization heat exchanger with liquid-solid circulating fluidized bed was investigated. The result showed that silica sediment-scaling curve was asymptotic with about 2.5 h induction period. The scaling mechanism was crystallization scaling combined with particulate scaling. When the particular inert solid particles were introduced into the heat exchanger to form liquid-solid circulating fluidized bed, the scaling layer deposited on heat transfer surface could be removed quickly and scale formation could be prevented completely, hence cleaning heat transfer was realized. The rate of the scale cleaning increased with the increase of fluid velocity and inert solid particle concentration. The scaling mechanism was not affected by inert solid particles. Based on the analysis of scale prevention mechanism of liquid-solid fluidized bed heat transfer, a mathematical model for silica sediment scaling was proposed. The predicted value of scaling model is in good agreement with experimental data.