【作者】 张伟；

【导师】 王晓静；

【作者基本信息】 天津大学 ， 化工过程机械， 2019， 硕士

【摘要】 传统干燥过程主要是通过间壁传热和对流传热等方式直接蒸发物料中的表面水份。此过程效率低、能耗高、耗时长,很难达到快速烘干的要求。本课题研究的多孔材料主要应用于自主研发的烘干转筒干燥机内,用于解决某种特殊胶粒的连续快速干燥问题。多孔材料在锥筒下部与含湿物料接触,通过毛细作用将物料表面湿份吸附到多孔材料层内部,然后随锥筒转动与物料分离,并在夹套间壁传热和热空气对流传热的作用下快速脱水,由此实现多孔材料对胶粒吸附脱水的连续循环处理。因此,多孔材料的水份吸附与热导迁移机理成为本课题要解决的关键问题。为了研究多孔材料的吸附脱水性能,首先对多孔材料中毛细管的渗吸理论进行了研究。将圆形毛细管中流体的高度上升理论公式扩展到方形和三角形毛细管。然后对多孔材料的干燥过程进行了理论研究,分析了干燥过程各阶段的蒸发特征。得出毛细管孔径对多孔材料吸、脱水性能的影响。同时在理论研究的基础上,设计完成了多孔材料的吸、脱水实验。通过分析吸水实验数据,验证了孔径对于吸水性能的影响,并通过将理论吸水高度的计算结果与实验结果对比,验证了理论模型的正确性;通过干燥实验得出了三种试样(1、2、3)的干燥速率,验证了孔径对于蒸发性能的影响并对干燥过程理论研究做出了验证。综合理论与实验研究的结果,针对快速吸、脱水的工程背景需求,选择试样1(平均孔径约为232.11μm)更合适作为锥筒内衬材料。更多还原

【Abstract】 In traditional drying processes,surficial moisture of materials is directly evaporated mainly through surficial or convective heat transfer,which costs much energy and time and shows low efficiency.This subject focuses on a porous material that is used in a rotary drum dryer,applied to a continuous rapid drying process of particles of special material.The porous material contacts with the particles at the bottom of the taper cylinder,absorbing surficial moisture by capillary action,and then detaches with the particles by rotating synchronously with the cylinder.Heat transferred from the jacket and the atmosphere makes the moisture absorbed in the porous material evaporate fast and realizes the continuous cyclic drying process of the particles.Therefore,the mechanism of water absorption and evaporation of porous materials becomes the key issue to be studied.In order to investigate the moisture absorption performance of the porous material,capillary sorption theory is firstly studied.The theoretical formula of the liquid height in circular capillary is extended to square and triangular capillary.The theory of the material drying process is then studied.The evaporation characteristic of each stage during the drying process and the influence that the diameter of the capillary has on the absorption and dehydration performance of the porous material are investigated.The absorption and dehydration experiment of the porous material are designed and completed based on the theory studies.The relationship between the diameter of the capillary and its absorption performance and the correctness of the theoretical formula are verified comparing with the experimental data.The drying rates of three samples(1,2,3)are obtained through drying experiment and the relationship between the diameter of the capillary and its dehydration performance is verified.As a result of comprehensive consideration of theoretical and experimental result and the engineering demands,sample 1(average pore diameter of 232.11μm)is taken as the more suitable lining material of the taper cylinder.更多还原