多层水平气流带式干燥机的数学模型

根据干燥传质传热学原理和干燥动力学特性，建立了水平气流带式干燥机干燥过程的数学模型。该模型可以预测干燥机合理的通风道高度、带翻转最佳时间和热风风速等。为优化多层带式干燥机的结构或设计新的水平气流带式干燥机提供了理论依据。     

Mathematical model for spray drying

A mathematical model has been developed for dimensioning of spray driers. A critical moisture content which takes into consideration the solidifying of the surface of the particle has been introduced. In this way the model is applicable to porous particles. The model applies for changes in the transport coefficients.     

Freeze drying process: real time model and optimization

Freeze drying is a separation process based on the sublimation phenomenon. This process has the following advantages compared to the conventional drying process: the material structure is maintained, moisture is removed at low temperature (reduced transport rates), product stability during the storage is increased, the fast transition of the moisturized product to be dehydrated minimizes several degradation reactions. Freeze drying process has not been studied well enough. In order to put it to practice, a mathematical model based on fundamental mass and energy balance equations has been developed, based on a deterministic mathematical model proposed by Liapis and Sadikoglu [Drying Technol. 15 (3–4) (1997) 791], and used to calculate the amount of removed water and amount of residual water. The proposed model contains the freeze drying equations, which are solved by the orthogonal collocation and polynomial approximation—Jacobi method. The results show that the dynamic mathematical model represents well the process and is especially well suited for real time optimization. As a case study to illustrate the model utilization in a real time optimization procedure, the freeze drying process was optimized by the method of Successive Quadratic Programming (SQP) used for solution of non-linear equations, for skimmed milk and soluble coffee. The optimization procedure showed to be an important tool to improve the process performance since lower energy consumption and hence lower cost has been achieved to obtain the product with the same quality.     

转筒烘干机烘干活性白土的改进

转筒烘干机是一种处理量大的干燥设备,它广泛用于冶金、建材、化工等行业。而应用于活性白土的烘干还属探索阶段,本文根据活性白土的具体特性分析了烘干机的结构对活性白土的产量、质量等影响。１．活性白土生产简介活性白土主要应用于石油催化和矿物油、植物油等脱色。它是由高品位膨润土成品经过硫酸等活化处理、漂洗、固液分离、烘干、粉磨等工序制成的。它是主要质量参数有：活性度、脱色率、游离酸含量等。固液分离后的活性白土,含水量一般在３０～４５％,它具有很强的粘性,进入烘干机后,如果烘干机结构不适应,不但难以烘干,而…     

Influence of drum inlet air conditions on drying process in a domestic tumble dryer

This study examines how the inlet air temperature, relative humidity, and flow rate influence the textile drying process in an open cycle tumble dryer. An experimental setup was prepared by connecting a domestic tumble dryer to an external system for controlled heating, humidification, and transport of air. Experiments were conducted by drying cotton textiles (8?kg dry mass) at different air inlet conditions. On the basis of measured data, correlations for determination of the total drying time, the moisture evaporation rate during the constant drying rate, and the area-mass transfer coefficient were developed. The process in the drum was modeled by using an established moisture evaporation model, based on sorption isotherms. A commonly used and a recently reported sorption isotherm for cotton were used with the model. Agreement between calculated and measured drying curves was better in case of the commonly used sorption isotherm, but final moisture content was better predicted by the recently reported sorption isotherm.     

Nonlinear model of pneumatic conveying dryer for economic process control

Abstract

This paper presents a nonlinear dynamic model, suitable for economic process control of pneumatic conveying dryer for drying of food grains. The dynamic model is developed by reshaping the process equations derived for the batch drying, dilute phase, and a negative-pressure conveying system. The dynamic model parameters are identified by numerically solving a nonlinear least squares optimization problem, subject to a set of differential and algebraic equality constraints that describe the system dynamics and bounds in the parameters. A detailed parametric uncertainty and sensitivity analysis are performed providing valuable insight into the influence of critical model parameters on observables, the interplay among various parameter-state-measured disturbances, and quantifying uncertainties in the model. Further, different process economic performance and product quality indicator of uncertain dryer model are studied. The model validation study as performed with the underlying process shows a very good agreement in understanding necessary dynamic characteristics and interplay between the various parameter of interest.     

用于中药浸膏干燥的滚筒干燥机

对滚筒干燥机在罗布麻浸膏干燥上成功应用进行了研究,并与现有中药浸膏干燥机进行了对比分析,探讨了滚筒干燥机在中药浸膏干燥领域应用的可行性。     

Mathematical model for intermittent microwave convective drying of food materials

Intermittent microwave convective drying (IMCD) is an advanced technology that improves both energy efficiency and food quality in drying. Modeling of IMCD is essential to understand the physics of this advanced drying process and to optimize the microwave power level and intermittency during drying. However, there is still a lack of modeling studies dedicated to IMCD. In this study, a mathematical model for IMCD was developed and validated with experimental data. The model showed that the interior temperature of the material was higher than the surface in IMCD, and that the temperatures fluctuated and redistributed due to the intermittency of the microwave power. This redistribution of temperature could significantly contribute to the improvement of product quality during IMCD. Limitations when using Lambert’s law for microwave heat generation were identified and discussed.     

氯气干燥工艺的改进与优化

为解决原离子膜烧碱项目中氯气处理工艺存在的问题,在新建的20万t/a离子膜烧碱项目中采用2种塔型串联的氯气处理模式,并计算和绘制了塔的负荷性能图。按照负荷性能图对操作系统进行了优化。实践证明,改进后的干燥系统操作稳定,不但使处理后的氯气质量达到工艺指标,而且大大降低了浓硫酸的用量。既降低了生产成本,又减少了排放量。     

木材纤维管道气流干燥系统的流体力学分析

在中密度纤雏板（MDF）纤维管道气流干燥系统分析中常用的管道断面各项物理参数相同和纤雏在管道断面上均匀分布等多项假设，具有可靠的理论依据。与其说是假设，不如说是忽略次要因素的一种近似，或一种简化。     

脉冲式气流干燥过程的数学模型

通过分析脉冲式气流干燥器的结构特点 ,建立了主要包括颗粒的速度、湿含量、温度和空气的温度、湿度以及管径六个参数沿干燥管高度变化的数学模型。实验证明 ,该模型正确可靠 ,具有广泛的适用性。     

Influence of inner vapor transfer property of a freeze dryer on the design space of drying process

A freeze dryer with a radiative heating device was constructed and the inner vapor transfer property was regulated by separating the drying chamber and the condenser with an orifice. A mathematical model was used to obtain the contour diagrams of the selected parameters (e.g., product temperature and total drying period) during drying as a function of the heating condition and chamber pressure. Furthermore, the inner vapor transfer coefficients of the freeze dryer were used to draw the operation lines on the diagrams. The combinations of contour diagrams and operation lines clearly depict the design spaces. It was confirmed that the inner vapor transfer property substantially affected the acceptable operation range, and it was revealed that this coefficient is key to quantify the performance of a freeze dryer. This coefficient could also be used to predict the occurrence of choked flow during a freeze-drying run.     

An adsorption-sublimation model for a freeze dryer

A model has been constructed using material and energy balances in the dried and frozen regions of a material undergoing freeze drying. Both sublimatio and adsorption are accounted for in the set of coupled non-linear partial differential equations that constitute the model. Numerical solutions to thes equations are shown to agree quite closely with experimental data over the entire drying period.     

Statistical analysis of clothing drying in a venting type dryer

An experimental study of the drying process using the prototype of a venting type dryer is presented. The machine has two motors: one for moving the drum and another for moving the turbine; electrical resistance is used as the heat source. The prototype operates under controlled test conditions in accordance with the Department of Energy (DOE) Standard 10 CFR 430. The aim of this study is to statistically determine the impact of the main factors and their interactions involved in the drying of clothing from a complete design of experiments. Statistical analyses for drying time and the energy consumption are determined from the studied factors. The factors studied are turbine motor frequency (to admit and expel air from the dryer); power supplied to the electric coil, amount and moisture of clothing and restriction of exhaust duct the gases. The results show that all of the studied factors and four of the interactions are statistically significant in the drying of clothes. The shortest drying time and the lowest energy consumption were obtained with the higher level of restriction and the lower initial moisture of clothing.     

旋转气流喷动干燥机在漂粉精干燥工艺上的应用

常规的盘式干燥机在干燥漂粉精中存在能耗大、粉尘多以及DCS的控制连续性等问题。阐述了旋转气流喷动干燥机的工作原理、特点及其部件设计方案,设计并制造了二叶后掠式旋转搅拌器、密封装置及其他辅助设备。通过试验证明了旋转气流喷动干燥机在漂粉精工业生产中替代盘式干燥机的可行性:可节省占地面积50%,节省设备投资10%,生产1t漂粉精的蒸汽消耗可节省1.28t,产品收率>98%。     

旋转闪蒸干燥器干燥酒糟过程的实验研究

为获得旋转闪蒸干燥器干燥啤酒糟过程的最佳操作工况,对不同操作条件下的啤酒糟含水质量分数进行了测试,依据实验数据关联出了啤酒糟含水质量分数的计算公式。在此基础上对干燥过程进行寻优计算,得出干燥器所能达到的最低含水质量分数为3.92%,与实际对比误差为2.08%。满足要求含水质量分数(小于8%),处理量为75 kg时能量消耗最低的操作参数为进风温度94.9℃、轴向风速4.46 m/s,175 kg时进风温度155.9℃、轴向风速3.29 m/s,与实际对比误差小于1.65%。