城市垃圾在回转窑内传输过程的模型和优化

PREDICTION AND OPTIMIZATION OF TRANSPORT PROCESS OF MSW IN ROTARY KILNS

基于物料在回转窑内传输过程是由其在表面层内滚落运动和固定层内回转运动组成的这一特征 ,从散体运动的机理出发继承和发展了回转窑单颗粒轨道模型 ,并首次采用统计平均分析和受力矢量分析研究了窑内颗粒的运动轨迹 ,从而得出了平均停留时间 (MRT)和体积流率 (MVF)的简化模型 ,结合试验采取修正系数εt 和εf 完善了模型对非均质物料 (如城市垃圾 )、内构件等工况的适用性 ,同时对本文模型和几种已有的计算模型进行了比较研究 ,最后提出了回转窑热解反应器的设计和运行的优化模型 .

The bed material in a rotary kiln is characterized by two distinct regions:the relatively thinner active region in which the particles roll down the sloping bed surface and the much thicker stagnant region in which the particles are carried upward by the rotating wall. According to this characteristic, a single particulate trajectory model (PTM) is developed starting from intrinsic mechanism of granular flow.A simplified calculation equations involving MRT(mean residence time) and MVF (material volumetric flow) is derived, on the basis of both the vector analysis on axial displacement of individual particles in a single excursion and the statistical-averaged analysis on all excursions.Two modified coefficients ε t and ε f are proposed to improve model validity under practical cases such as irregular municipal solid wastes (MSW) existence and internal structure usage. The newly derived equations of PTM are compared with those proposed by previous workers to show their advantages. Finally,an optimal model for both operation and design of a special rotary kiln pyrolyser is presented and the corresponding optimization solution is given in detail.