STUDY ON THE THREE-PHASE CIRCULATING FLUIDIZED BED WHEAT STRAW BLACK LIQUOR EVAPORATOR

摘要

A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China's papermaking industry. It is treated by alkali recovery, in which evaporation is a key process. Experiments have been conducted in a 34mm diameter 1.2m high stainless steel column, in which a vapor-liquid-solid flowing formed. The three-phase boiling heat transfer coefficient has been measured under different operating parameters: circulating velocity, electrical heating flux, particle's volume concentration and kinds of particles. The experimental results show that the boiling heat transfer coefficient is enhanced by 20percent(approx)40percent than that of a vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits excellent fouling prevention.