Surface Profile Optimization of Yankee Dryer Based on Finite Element Analysis

The deformation and stress distribution of cast iron Yankee dryer caused by outside linear load， inside steam pressure and self-gravity were calculated by numerical simulation with ANSYS software. The deformation curve of the linear load area was obtained and compared with the deformation in the actual working process. The surface profile of dryer was optimized and the deformation and stress of the optimized dryer were calculated and compared with the that of before optimization. In this paper， the method of the surface profile optimization of Yankee dryer was presented．     

催化裂化催化剂喷雾干燥过程CFD模型

基于气固两相流理论和计算流体力学（CFD）知识，结合催化裂化催化剂喷雾干燥过程的特点，运用欧拉-拉格朗日(Eulerian-Lagrangian)模型，建立喷雾干燥塔两相流CFD模型，对制备催化裂化催化剂的喷雾干燥塔内气浆两相流动量、质量和热量传递过程进行数值模拟计算。通过模拟计算结果分析，可以得到喷雾干燥塔内流速分布、温度分布以及颗粒运行轨迹等信息，从而对塔内流场信息进行可视化。将模拟结果与中型喷雾干燥塔实验数据进行对比，结果表明二者趋势一致，出口温度误差在10%以内，证明所建模型可靠，可用于喷雾干燥过程的模拟。     

Drying Efficiency of Indonesian Lignite in a Batch-Circulating Fluidized Bed Dryer

This research explores the production of low-moisture, high-rank coal using a batch-type, laboratory-scale, circulating fluidized bed to dry low-rank Indonesian coal with a high moisture content of 35 wt%. The operation was performed using air as a fluidization gas in a riser (a 4-m-tall pipe with an inner diameter of 0.04 m) at a gas velocity ranging from 2.0 to 2.7 m/s and a riser temperature of 80 to 150°C. The electric heaters were installed in the upper part of a downcomer to prevent the condensation of the evaporated moist- ure. The drying rate of the coal was investigated in terms of the inlet gas temperature, the gas velocity, and the drying time in order to determine the optimum operating conditions. Changes in the moist- ure content of the coal, before and after the experiments, were char- acterized by a proximate analysis, an ultimate analysis, the higher heating value (HHV), the lower heating value (LHV), a particle size analysis, and by the equilibrium moisture content. The results show that 70 to 80 wt% (wet basis, wb) of the total moisture can be reduced when the gas velocity of the riser is 2.0 m/s and the gas temperature is 150°C. In experiments, a simple mathematical model based on the heat and mass balances and a thin-layer drying model were simul- taneously used to predict the drying behavior of coal under the given operating conditions. The results of the model are similar to those of the experiment.     

Mathematical Modeling the Drying of Poplar Wood Particles in a Closed-Loop Triple Pass Rotary Dryer

Closed-loop drying systems are an attractive alternative to conventional drying systems because they provide a wide range of potential advantages. Consequently, type of drying process is attracting increased interest. Rotary drying of wood particles can be assumed as an incorporated process involving fluid–solid interactions and simultaneous heat and mass transfer within and between the particles. Understanding these mechanisms during rotary drying processes may result in determination of the optimum drying parameters and improved dryer design. In this study, due to the complexity and nonlinearity of the momentum, heat, and mass transfer equations, a computerized mathematical model of a closed-loop triple-pass concurrent rotary dryer was developed to simulate the drying behavior of poplar wood particles within the dryer drums. Wood particle moisture content and temperature, drying air temperature, and drying air humidity ratio along the drums lengths can be simulated using this model. The model presented in this work has been shown to successfully predict the steady-state behavior of a concurrent rotary dryer and can be used to analyze the effects of various drying process parameters on the performance of the closed-loop triple-pass rotary dryer to determine the optimum drying parameters. The model was also used to simulate the performance of industrial closed-loop rotary dryers under various operating conditions.     

Air-Drying of Seeds: A Review

Beginning with harvesting, seeds are usually subjected to a series of processes which include drying for immediate or future use. Seed quality can be influenced by several factors during drying. This article presents a review of the seed air-drying process, including mathematical models based on differential equations derived from mass and energy balances for seeds and air in fixed and moving bed dryers. The article concludes with an overview of several potential drying technologies that can be applied to seeds.     

大容量低温水溶性PVA纤维生产线的开发

简介了低温水溶性PVA纤维的性能特点、应用领域、国内现状和纺丝工艺。结合以往低温水溶性PVA纤维生产线的设备配置情况,并根据单机设备的特点和适用范围,对产能为1 800 t/a的低温水溶性PVA纤维生产线的流程进行了设计。重点对该生产线上主要专用设备的工艺特点和结构特点进行了分析。指出若要进一步提高产能,纺丝机可考虑采用层叠式结构,干燥机导丝辊的支撑方式应考虑采用双支撑式结构。     

回转干燥机滚圈与筒体连接形式的改造

通过计算,分析瓮福化工公司60万t/a磷酸二铵生产线回转干燥机滚圈与筒体松套连接的弊端,确定滚圈与筒体采用固定式胀紧连接的改造方案。通过改造,保证了滚圈与筒体连接的同心度,有效避免了筒体碾压滚圈运行的情况,托轮振动明显减小,滚圈使用寿命延长。     

热泵干衣机仿真与优化

本文建立了热泵干衣机数学模型,包括稳态的热泵系统模型和动态的衣物干燥过程热质交换模型。利用模型仿真研究了各部件大小的匹配关系对单位能耗除湿量SMER和干燥时间的影响,并对重要的系统参数如循环风量、新风比例和制冷剂充注量进行了优化研究。将模型结果与实验结果进行了对比,干衣时间的误差小于3 min,耗电量的误差为-2.3%。结果表明,循环风量180 m~3/h、新风比例9%~10%时SMER最大;在冷凝温度限值之内,增加充注量有利于SMER的提高。研究结果可供热泵干衣机设计参考。     

抛砖引玉谈干燥

详细论述了砖坯干燥室及焙烧窑预热带干燥的重要性,针对不同窑型还提出了相应的避免干燥裂纹的措施。     

Water desorption isotherm and drying characteristics of green soybean

There is very little published information on green soybean about moisture sorption and drying. Water desorption isotherms were determined by the static gravimetric method using saturated salt solutions at 20, 30, and 40 °C. By comparing the index of goodness of fit, the isotherm for green soybean seeds could be better described by the Halsey equation with the desorption isotherm parameters A and B estimated to be 5.612 and 1.538 respectively. The net isosteric heat of water desorption calculated by Clausius–Clapeyron equation was from 208.8 to 3627.9 kJ/kg. Thin layer drying of green soybean seeds in a range of 25–45 °C and relative humidity from 0.2 to 0.4 dec were carried out with a heat pump dryer. The Page model was the most suitable model for describing the thin layer drying process of green soybean seeds compared with the Lewis, Henderson and Thompson models. The drying characteristics of green soybean seeds were tested and analyzed under various temperature and humidity conditions, and the results will be useful for the drying and storage of green soybean seeds.