褐煤脉冲式气流干燥传递过程研究

褐煤干燥是褐煤固体热载体新法干馏工艺的重要组成部分。本文对脉冲式气流干燥器内基于气-固两相流的褐煤干燥动量、热量、质量传递过程进行了研究。依托高效成熟的气流干燥技术,以颗粒在气流中的受力情况为基础,建立了气流干燥过程中颗粒加速运动的热量传递模型和颗粒减速运动的动量及热量传递模型,并提出了新的脉冲式气流干燥器高度的设计及优化方法。通过将脉冲式气流干燥器的干燥模拟数据与相同高度的等径式气流干燥器的数据进行对比,验证了脉冲式气流干燥的高效性,并根据烟气温度、颗粒湿含量、体积传热系数等模拟参数沿干燥器高度的分布情况对其高效性的原因进行了详细分析,为脉冲式气流干燥装置工艺设计提供准确的数据依据和理论参考。     

聚合物直接干燥用真空排气式挤压机的设计与应用

前言聚合物溶液干燥后处理,采用真空排气式挤压机进行直接干燥是一种新型工艺,它具有流程短,设备少,耗能低等特点。我院曾试制一台三阶真空排气式挤压机,在年产十吨规模的1,2-聚丁二烯树脂中试装置(以下简称树脂装置)中进行了试验和应用。该装置是以丁二烯为原料,抽馀油(沸程60～90℃)为溶剂,丁基锂为催化剂。聚合所得的胶液,经水洗,终止和脱水脱油处理后,仍含有30％左右的溶剂,需经干燥处理,使合格产品挥发份含量低于1％。最初     

氯硅烷歧化反应催化剂干燥特性及催化性能

研究了氯硅烷歧化反应催化剂Amberlyst 21和改性后树脂B的干燥特性,考察了供热温度和料层厚度对催化剂干燥规律的影响,并建立了干燥曲线的半经验关联式。此外,还通过滴定法测量了树脂活性官能团含量,最终通过实验检验催化效果。结果表明:树脂B和Amberlyst 21的干燥规律基本类似,得到最优的干燥温度及物料层厚度分别为70℃和3 cm,含水质量分数降至5%时干燥时间分别为23.3,20.0 h。在最优干燥条件下,树脂B的胺基含量略高于Amberlyst 21,2种树脂均可作为三氯氢硅歧化反应的催化剂,且树脂B的催化效果优于Amberlyst 21,反应转化率可达23.42%。     

文摘

<正> 这种称之为Unison干燥器的高频率脉冲干燥装置非常适合干燥加工热敏性化工产品、食品和药剂等,输入原料可以是浆状和乳化液状。该干燥装置采用了一种脉冲式燃烧器,能产生高振幅、高频率脉冲振动,使输入的原料分散成为细小的液滴。     

新型旋转式干燥机

最近 ,旋转式干燥机在塑料生产的应用已有很大的进展。设备生产商声称 ,以单个连续旋转式干燥器取代双塔式干燥剂 ,可以消除露点且达到更高的控制水准。　　普通干燥机在干燥树脂之前 ,使用两或四个干燥垫以产生热气流。一般而言 ,一个干燥垫把湿气从空气中除掉 ,然后加热并穿透过树脂。干燥垫吸潮后 ,气流再转到另一个新的干燥垫 ,用过的干燥垫则进入更新阶段 ,需加热到 40 0°F以达到干燥湿气的效果。　　有些干燥机供应商称 ,这种设备存在的问题是气流转入干燥垫时 ,有露点和湿度变化的缺陷。旋转式干燥机不需要更换干燥垫 ,加工过程更…     

离子交换树脂流化床干燥工艺的研究与改进

对离子交换树脂的两种流化床干燥工艺作了简单介绍,重点介绍了一种利用流化床连续干燥系统对离子交换树脂进行干燥冷却的工艺。此工艺针对离子交换树脂的特点进行设计。试验证明该工艺具有投资少和节能高效的特点,有很好的推广前景。     

聚丙烯树脂干燥过程中两种不同工艺路线择选的讨论

目前,在聚丙烯树脂生产的干燥过程中,存在着两种不同工艺路线的争论。一种是采用氮气流作热载体进行干燥以保证树脂质量和保证生产完全;另一种是以空气作热载体进行干燥。它是上海、北京的广大工人、技术人员为了尽快的拿到自己的国产树脂而根据我国当时     

气流干燥塔恒温自控

一、概述 我厂聚氯乙烯树脂的干燥是采用一次气流干燥和一次沸腾干燥。温度的控制是气流干燥工艺控制的主要指标。开始,我厂气流干燥塔是由三级变速电机带动螺旋输送机向气流塔内供料的,由于三级变速电机调速范围小,且速度变化是阶跃式的,加之加热蒸汽压力经常波动,造成气     

怎样比较干燥机：没有简单答案的复杂挑战

一种类型的树脂干燥机会比另一种更快．更具能效吗？又该如伺对其干燥性能进行比较呢？日前,Novatec公司对4种干燥设备进行了一项可控式干燥测试,然而此次试验的合理性和客观公正性却备受争议。     

气流干燥过程的数学模拟

针对颗粒和空气在干燥管内的相互作用和传质传热机理,首先建立了直管式气流干燥数学模型,然后通过分析脉冲式气流干燥器的结构特点,求出了管径变化的微分方程,将其和直管式气流干燥的五个常微分方程耦合在一起,构成了脉冲式气流干燥的传质传热数学模型。根据模型方程的特点,运用四阶龙格-库塔法对其进行了数值求解。通过实验结果验证,该模型正确可靠。     

VMI系列四鼓成型机机械鼓改用胶囊鼓的可行性分析

列比机械式反包成型鼓与一胶囊式反包成型鼓在机械结构及使用上的特点,并分析两种结构的成型鼓在胎坯生产过程中的优缺点,得出胶囊式反包成型鼓优于机械式反包成型鼓的结论。从而,根据对现有使用机械式反包成型鼓的荷兰VMI四鼓成型机在操作流程、生产工艺、程序控制等方面的分析,得出机械式反包成型鼓更换为胶囊反包成型鼓具有可行性的结论。     

A Diffusion Model for a Drum Dryer Subjected to Conduction, Convection, and Radiant Heat Input

Drum dryers are commonly used for production of a flaky dry powder from thick suspensions. This article presents results of a simple diffusion-based model to predict the drying performance of a pilot-scale twin-drum dryer. Numerical results are compared with experimental data obtained for a biological sludge whose initial moisture content varied from 1.0 to 2.3 kg/kg db. The agreement of model predictions with the pilot-scale experimental data is favorable. Effects of film thickness, drum rotational speed, external air flow velocity, and its humidity are examined parametrically. Sludge film thickness is identified as the most critical operating parameter to control the final moisture content and productivity of the dryer. The validated model is used to predict performance of a drum dryer subjected to heat input by convection and radiation along with conduction through the drum wall. It is shown that dryer output can be enhanced significantly by increasing the film thickness and applying radiant heating in the initial period of drying. A simple mathematical model of this type can be used for the purpose of design and analysis as well as scale-up of industrial drum dryers based on simple laboratory-scale experiments.     

THERMAL CONTACT CONDUCTANCE OF A COATED PAPER/METAL INTERFACE

A better understanding of the parameters associated with heating of the coated paper during drying process would permit a more accurate design and control of the process to achieve an improved coated paper quality and printability. Following the application of the coating, the coated paper passes through non-contact dryers (i.e. infrared dryers and impinging hot air dryers). When the coating has coalesced, further drying is achieved with steam-heated, contact dryers. One parameter affecting the heat transfer from a metallic dryer drum to the coated paper is the thermal contact conductance at the interface between the coated paper and the drum. In this paper, the thermal contact conductance of a coated paper/metal interface is determined and compared to that of the uncoated paper. Two types of base stock and one type of coating are considered. The thermal contact conductance values are given as a function of the applied interface pressure.     

THERMAL CONTACT CONDUCTANCE OF A COATED PAPER/METAL INTERFACE

A better understanding of the parameters associated with heating of the coated paper during drying process would permit a more accurate design and control of the process to achieve an improved coated paper quality and printability. Following the application of the coating, the coated paper passes through non-contact dryers (i.e. infrared dryers and impinging hot air dryers). When the coating has coalesced, further drying is achieved with steam-heated, contact dryers. One parameter affecting the heat transfer from a metallic dryer drum to the coated paper is the thermal contact conductance at the interface between the coated paper and the drum. In this paper, the thermal contact conductance of a coated paper/metal interface is determined and compared to that of the uncoated paper. Two types of base stock and one type of coating are considered. The thermal contact conductance values are given as a function of the applied interface pressure.     

聚酯切片干燥除湿系统

对聚酯切片干燥除湿系统及其典型设备如冷冻式除湿机 ,转轮式除湿机和分子筛除湿机进行了介绍和分析。指出冷冻式除湿与分子筛吸附相结合是切片干燥除湿系统的优选配置。     

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。     

EXPERIMENTAL STUDY ON DRYING OF CHILLI IN A COMBINED MICROWAVE-VACUUM-ROTARY DRUM DRYER

This paper presents new data on drying chilli in a microwave-vacuum-rotary drum dryer. This novel technique is designed to combine the advantages of vacuum drying and evenly dispersed microwave energy in a rotary drum. The drying kinetic and the specific energy consumption at particular product moisture content were measured experimentally. Moreover, the effect of pressure inside the chamber and the rotational speed of the drum were also determined.     

EXPERIMENTAL STUDY ON DRYING OF CHILLI IN A COMBINED MICROWAVE-VACUUM-ROTARY DRUM DRYER

ABSTRACT

This paper presents new data on drying chilli in a microwave-vacuum-rotary drum dryer. This novel technique is designed to combine the advantages of vacuum drying and evenly dispersed microwave energy in a rotary drum. The drying kinetic and the specific energy consumption at particular product moisture content were measured experimentally. Moreover, the effect of pressure inside the chamber and the rotational speed of the drum were also determined.     

Modeling of heat pump tumble dryer energy consumption and drying time

The use of heat pump tumble dryers is nowadays more common because they offer huge energy savings compared to conventional tumble dryers. Earlier studies made on conventional tumble dryers have shown that parameters such as heater power, fan speed, drum speed, weight and initial moisture content of textiles and air leakage have a huge impact on the energy efficiency and drying time. In the present study, a modified commercial heat pump tumble dryer was evaluated for energy consumption and drying time by changing operating parameters including fan speed, drum speed, and mass load. The total energy consumption and drying time were measured and corrected for the initial and final moisture content in the textiles. The experimental results based on 27 drying tests were evaluated to develop linear regression models for energy consumption and drying time, which show a good agreement with the experimental data. The results show that a large mass load, a high drum speed, and a low fan speed give the highest energy efficiency, i.e. the lowest energy consumption per kg of drying load. Larger loads extend the length of the drying cycle while higher fan and drum speeds result in shorter drying time.     

Drum drying performance of condensed distillers solubles and comparison to that of physically modified condensed distillers solubles

Condensed distillers solubles (CDS) is a viscous, syrupy co-product of ethanol production from corn or other starchy grains; CDS exhibits strong recalcitrance to drying due to its chemical composition, which includes a substantial amount of glycerol. The objectives of this study were to determine the drum drying performance of CDS and to compare it to that of a physically modified CDS (MCDS) having a reduced glycerol level. Material type (CDS vs. MCDS), dwell time, drum internal steam temperature, and gap width were evaluated for their effects on the final moisture content, water activity, and color of the dried product. While both CDS and MCDS could be dried to a range of endpoint moisture contents, dried CDS exhibited a narrow range of water activity compared to that of MCDS. Gap width was found to be the predominant factor affecting dried product color. This work demonstrates that drum drying can effectively reduce the moisture content of CDS, even though the water activity of the dried product cannot be reduced beyond ∼0.45. In contrast, MCDS can be readily drum-dried into a shelf-stable, flaked product with a pleasing appearance.