基于颗粒粒径分布的褐煤烟气干燥过程建模  

Modeling of lignite drying with various particle size distributions

作　　者：尹炜迪[1] 吴玉新[1] 吕俊复[1] 郝正虎[1] 张守玉[2] 

机构地区：[1]清华大学热能工程系,热科学与动力工程教育部重点实验室,北京100084 [2]上海理工大学能源与动力学院,上海200093

出　　处：《清华大学学报（自然科学版）》2014年第9期1190-1196,共7页Journal of Tsinghua University(Science and Technology)

基　　金：国家"九七三"重点基础研究项目(2012CB214900)

摘　　要：褐煤在制粉系统干燥下降管中的温度历程决定了其脱挥发份过程,影响了系统的安全和可靠性。粒径分布不均是下降管中的褐煤干燥过程的重要特点。该文基于颗粒内部的干湿区和退缩蒸发界面假设构建褐煤干燥模型,研究了不同粒径分布下褐煤的干燥过程,并对于实际工况和影响因素进行了分析。结果表明,干燥过程开始受到小颗粒控制,随后受大颗粒控制。小颗粒的干燥过程可以分为干燥阶段、升温阶段、降温和平衡阶段。实际情况下,毫米级小颗粒在干燥管中具有可燃挥发分析出的危险,其主要影响因素是初始烟气温度与平衡温度;窄粒径分布可以减少小颗粒份额,降低可燃挥发分析出的影响。The temperature history of the lignite determines the devolatization in the drying tube of the pulverizing system, which affects the safety and reliability. The nonuniform particle size distribution is an important factor affecting the lignite devolatization in the tube. This paper uses a model which assumes a wet-dry section with a shrinking evaporation interface to analyze the lignite drying processes for various particle size distributions were analyzed. The results show that the drying process is controlled at first by the small particles, followed by the large particles. The temperature history of the small particles can be divided into the drying stage, the heating stage, the cooling stage and the balance. Millimeter sized particles can emit combustible volatiles for typical industrial conditions. The key factors are the initial and equilibrium temperatures. Narrow particle size distributions will reduce the number of small particles and the effects of the combustible volatiles.

关 键 词：褐煤干燥 粒径分布 制粉系统 温度历程 

分 类 号：TQ536.1[化学工程—煤化学工程]