高温烟气中单颗粒褐煤干燥特性实验研究

Experimental Research on Single Lignite Particle Drying Process in Hot Gas

针对褐煤低温烟气干燥技术中干燥效率低、燃烧爆炸危险系数高等问题,对高温烟气干燥技术进行了研究.通过单颗粒高温烟气干燥实验,得到了不同烟气温度、粒径及初始含水率下的干燥曲线、干燥速率曲线、颗粒表面温度曲线,以此来研究3个因素对褐煤高温脱水效果的影响.结果表明,高温(≥600℃)烟气干燥速率远大于低温热风(≤200℃)干燥速率,但继续提高烟气温度对临界含水率的影响很小,同时对干燥速率的提升也不如低温干燥显著;初始含水率越高,干燥速率越大,表面温度越低;粒径越小,对干燥速率和临界含水率的影响越大,且大于干燥介质温度和煤球初始含水率的影响.

Compared to the low temperature air drying process,the high temperature flue gas drying of lignite has advantages of reduction of fire and explosion hazards as well as improving drying efficiency.Therefore,the parameters （gas temperature,particle size,initial water ratio） that affect the drying process of a single particle were studied.Moreover,the drying curves,the drying rate curves and the surface temperature curves of particles under different initial gas temperature,particle size and initial water ratio were obtained by experiments.It is found that the drying rate of the high temperature （≥600 ℃）flue gas is beyond that of the low temperature （≤200 ℃ ）air significantly .But the further rise of the gas temperature has only a very weak influence on the critical water ratio and the drying rate when comparing with the low temperature air drying.With the increase of initial water ratio,the drying rate increases,whereas the surface temperature decreases.Besides,a smaller particle size exerts much more influence on the drying rate and critical water ratio than the gas temperature and initial water ratio.