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通过分析回转干燥器内传热传质规律,建立生物质回转干燥过程的一维数学模型。利用基于随机颗粒轨道模型的物料体积流率公式计算干燥器内各传热面积大小,从而实现模型的求解。采用此模型预测物料温度、含水率及空气温度、湿度等在干燥器内部的轴向分布,计算结果与文献实验数据的对比结果表明该模型可用于实际生物质回转干燥过程的分析。干燥计算结果表明:物料在干燥器入口段干燥速率最大,直至物料含水率达到临界含水率后逐渐减小,物料中水分的蒸发主要发生在干燥器的前端。因此,要提高生物质物料的干燥程度,最直接有效的方法是提高物料入口段的干燥速率,可通过提高干燥空气入口温度等手段实现。
By analyzing the heat and mass transfer laws in the rotary dryer, a one-dimensional mathematical model of the biomass rotary drying process is established. The size of each heat transfer area in the drier is calculated by using the material volume flow rate formula based on the random particle orbit model to solve the model. The model was used to predict the axial distribution of material temperature, moisture content, air temperature and humidity in the dryer. Comparing the calculated results with the experimental data, the results show that the model can be used to analyze the actual biomass rotary drying process. The results of drying calculation show that the material has the highest drying rate at the inlet of the dryer until the moisture content of the material reaches the critical moisture content and then decreases gradually. The evaporation of moisture in the material mainly occurs at the front of the dryer. Therefore, the most direct and effective way to improve the drying degree of biomass materials is to increase the drying rate of the material inlet section, which can be achieved by increasing the inlet temperature of the drying air.