流化床选择性排渣的实验研究

摘要

A method of bottom ash discharging and separating in fluidized beds was proposed by unequal distribution of wind speed,which is based on separation theory of fluidization and difference of particle terminal velocity.A visible cold test-bed was built to evaluate the effects of the pressure distribution,fluidization velocity and particle size distribution on discharging and separating.Experimental results showed that reasonable pressure distribution characteristic resulted in particles circulation in the fluidized bed.The increasing ratio between high wind speed and low wind speed led to the better separation effect.However,due to the mixing of fine particles with coarse particles,particle separation effect was greatly reduced by the increasing fine particle volume fraction.Bottom ash discharging with unequal distribution of wind speed can realize particle separation.%根据流态化分选和终端速度差异分选原理,提出了一种采用不均等配风的选择性排渣的方法,搭建了流化床选择性排渣的可视化冷态实验台,研究了压力分布、流化风速、床料粒径分布对排渣分选效果影响.结果表明:不均等配风时,由床内压力分布特点可知床内颗粒存在循环流动特点;当高风速与低风速的比值越大,其对颗粒度分选效果越好;在相同的高风速与低风速比之下,随床内细颗粒比例的增加,由于粗细颗粒的混合程度增加,分选效果会变差;不均等配风的排渣方式能够实现对细颗粒的分选.