黑索今连续干燥试验及其动力学研究

Drying Experiment and Kinetics of RDX in a Continuous Dryer

通过试验和数值计算对黑索金的连续干燥特性及其动力学特征进行了研究。采用一种最新研制的干燥机对初始含水量6%的黑索今进行了连续干燥脱水试验,并运用经验和半经验薄层干燥方程对试验数据进行拟合分析,计算得到黑索今干燥过程的干燥数学模型,在线跟踪监测干燥过程中的水分、静电和温度的分布,运用菲克扩散方程计算得到黑索今干燥过程的有效扩散系数。结果表明,黑索今干燥过程没有经历恒速干燥阶段,而是经过短暂的升速阶段后直接进入降速干燥阶段,最终产品水分含量均≤0.1%,满足工业生产使用的要求;试验选择Midilli-Kucuk模型作为黑索今干燥的最佳薄层干燥数学模型;干燥过程中的静电和温度的分布均满足安全操作要求;有效扩散系数达10-8数量级。

Experiments and numerical calculations were conducted to investigate the continuous drying characteristics and dynamics of RDX. The drying characteristics of RDX with initial moisture content 6% were investigated in a continuous drying equipment. In order to estimate and select the suitable form of RDX drying curves,the curves were fitted to some different semi-theoretical and/or empirical thin-layer drying models and coefficients are evaluated by non-linear regression analysis. Moisture content,static electricity and temperature in the drying process were on-line monitored. Furthermore,Fick diffusion equation was used to determine the effective diffusion coefficient in the drying process of RDX. The results indicate that,there is a falling rate period after a short warm-up period and no constant rate period is observed. The moisture content of the product obtained is less than 0.1%,satisfying the product demand. It is deduced that Midilli-Kucuk model has shown a better fit to the experimental drying data as compared to other models. The surface electrostatic charge and temperature distribution of the drying and cooling layer of RDX is rather acceptable for the safe operation. The drying efficiency is improved with the effective diffusion coefficient up to the order of 10-8.