真空低温连续干燥工业自动化生产线关键技术研究

通过对真空低温连续干燥生产线工艺性分析和关键技术研究,建立了300t／d高水分玉米真空低温连续干燥工业自动化生产线,并对生产线系统进行了生产性试验和关键技术验证分析。试验验证表明,该真空低温连续干燥新技术具有节能高效、绿色环保、干燥品质好的特点,是我国解决粮食干燥问题的一条新途径,是我国绿色干燥技术的发展方向。     

聚酯切片连续干燥中除湿系统的改造

<正>本公司于1991年筹建1992年投产,现有规模为两套400kg/h产量的FDY生产线,两套600kg/h产量的POY和DTY生产线.其中两套600kg/h产量POY生产线连续干燥的除湿系统,是采用室温空气经冷冻脱水后氯化锂纸轮深度除湿工艺路线,给生产带来许多麻烦和损失.其一,由于直冷式除湿型冷冻机只能设置在干燥区内,而一般的操作人员缺乏专业知识,加上冷冻机自身的质量问题和复杂性,导致夏季无法正常生产而且其维修费用很高.其二,由于氯化锂纸轮自身质量问题及结构问题,容易造成干湿空     

低温真空连续干燥技术及其塔形设备研制初步探讨

减少干燥加工过程物料内的热敏物质损失，降低干燥加工能耗及设备运行成本，降低设备制造成本，是干燥技术及设备的研究发展方向。低温真空连续干燥塔式设备成功使用了真空干燥技术、高气密性旋转阀进排物料、高换热面积与容积之比的干燥筒仓、筒仓中物料靠重力在换热管件之间自上而下的混合流动中被加热，从而实现了高质量、大产量、低能耗、低运行成本的干燥加工。     

计算机监控系统在盘式真空连续干燥器中的应用

阐述了采用计算机控制系统实现盘式真空连续干燥器的全自动控制,介绍了有关计算机主要研究开发内容和控制系统的结构、工作原理、可靠性和故障处理等。     

真空干燥冷却工艺的发展

本论证通过洗衣皂真空干燥冷却设备的改进，可使之成为既能生产洗衣皂，也可生产半透明皂的多功能生产设备。     

木材真空干燥设备加热系统理论计算的探讨

将过热蒸汽作为干燥介质,推导了木材真空干燥设备加热系统的理论计算方程,并以厚度为40mm,初含水率从60%干至10%的红松为标准材,对真空干燥设备的加热系统进行了理论计算,比较分析了绝对压力对计算结果的影响。     

Analysis of the Vacuum Drying Rate for Red Oak in a Hot Water Vacuum Drying System

Red oak boards of 76.2 cm (long) × 7.62 cm (wide) × 2.54 cm (thick) were dried from green moisture content (MC) to 7% MC in the hot water vacuum-drying system. These boards were dried at the pressure of 12 mm Hg and the temperatures ranging from 30 to 50°C within 25 to 70 h. Drying rates were measured and drying curves were calculated. The results showed that the drying rate was higher at higher temperatures. The vacuum drying was faster when wood MC was above 30% than when it was less than 30%. The individual samples did not dry at the same drying rates even at the same drying conditions because of anatomical variations between boards.     

粮食真空低温干燥新技术的优势

真空低温干燥技术是近年来被广泛应用的一项新技术。就近年来真空低温干燥技术在东北玉米干燥方面的应用研究及其进展作了综述。探讨了真空干燥技术在玉米方面的应用前景。     

Validation of a Novel in Situ Weighing System During Vacuum Drying

In the presented article, an in situ weighing system for the measurement of drying rate and residual water content during vacuum drying was tested and validated with offline analyses. The influence of buoyancy effects was studied both experimentally and theoretically in terms of sample volume and final pressure. Furthermore, the effect of time drifts on the measured drying rate and residual water content were studied and the measurement errors were quantified for the drying of sorbitol solutions. It was shown that the drying rate and thus residual water content could be determined with good accuracy with the present measurement system.     

洋葱真空干燥动力学研究

为研究洋葱在真空干燥条件下的干燥特性,选用不同干燥条件对洋葱进行脱水处理,测定不同工艺条件下洋葱的干燥曲线和干燥速率曲线。结果表明,温度和真空度对洋葱真空干燥过程都有明显的影响,且洋葱真空干燥的动力学模型符合Page方程,并得到本试验条件下的动力学模型。     

A Vacuum Drying Model for Mango Pulp

Vacuum drying of mango pulp at varying conditions of pulp thickness (2, 3, and 4 mm) and vacuum chamber plate temperature (65, 70, and 75°C) was carried out under 30-50 mm of mercury absolute pressure. A model based on moisture diffusivity was found to give close prediction to moisture content of the pulp at different times of drying with correlation coefficient varying between 0.98-0.99 for pure mango pulp and pulp with ingredients. Color change of reconstituted pulp made from mango powder was found to depend more on pulp thickness than plate temperature. For getting low color change vacuum drying should be carried at maximum pulp thickness of 2.6 mm and vacuum chamber plate temperature of 72.3°C.     

A Vacuum Drying Model for Mango Pulp

Abstract

Vacuum drying of mango pulp at varying conditions of pulp thickness (2, 3, and 4 mm) and vacuum chamber plate temperature (65, 70, and 75°C) was carried out under 30–50 mm of mercury absolute pressure. A model based on moisture diffusivity was found to give close prediction to moisture content of the pulp at different times of drying with correlation coefficient varying between 0.98–0.99 for pure mango pulp and pulp with ingredients. Color change of reconstituted pulp made from mango powder was found to depend more on pulp thickness than plate temperature. For getting low color change vacuum drying should be carried at maximum pulp thickness of 2.6 mm and vacuum chamber plate temperature of 72.3°C.     

Predicting Thermal Efficiency in Timber Radio Frequency Vacuum Drying

Abstract

In this work, the efficiency of transforming dielectric energy into evaporated water is analyzed for the case of timber radio frequency vacuum drying. Based on well-known heat and mass transfer equations, a simplified mathematical model is proposed that estimates the drying efficacy in regards to the thermo-physical properties of wood. Although not exact, the theoretical results are close to the experimental observations and elucidate some phenomena like the tendency of the timber to dry from inside to outside, and the drying rate increase with the rise of the timber gas permeability. The theoretical efficiency model also predicts a range of wood permeability values for which the drying efficiency changes from 100 to 0%, thus providing a quantitative scale for classifying the spectrum of “difficult-to-dry” all the way to “easy-to-dry” wood species when using radio frequency vacuum technology.     

Predicting Thermal Efficiency in Timber Radio Frequency Vacuum Drying

In this work, the efficiency of transforming dielectric energy into evaporated water is analyzed for the case of timber radio frequency vacuum drying. Based on well-known heat and mass transfer equations, a simplified mathematical model is proposed that estimates the drying efficacy in regards to the thermo-physical properties of wood. Although not exact, the theoretical results are close to the experimental observations and elucidate some phenomena like the tendency of the timber to dry from inside to outside, and the drying rate increase with the rise of the timber gas permeability. The theoretical efficiency model also predicts a range of wood permeability values for which the drying efficiency changes from 100 to 0%, thus providing a quantitative scale for classifying the spectrum of “difficult-to-dry” all the way to “easy-to-dry” wood species when using radio frequency vacuum technology.     

Experimental Study on Microwave Vacuum Drying of Two-Porosity Level Media

Microwave vacuum drying experiments were performed on a laboratory scale dryer with a two-level porosity material: a packed bed of porous alumina beads. The incident microwave power and the vacuum pressure level were fixed, the main varying parameters being the beads diameter and porosity, and the mean pore diameter. The drying kinetics and the evolution of the product temperature are presented. The drying kinetics can be divided into two main periods. The first one corresponds to the drying from the bed voids according to evaporation mechanism that we describe with a stagnant film law. The second one corresponds to the drying from the particle pores and we divide it into two parts: we suggest that the former is dominated by capillarity driven moisture transport, and the latter is limited by the desorption kinetics of the few water layers left.