氧化锆料浆性能对其喷雾造粒粉料性质的影响

本文研究了料浆含固量和粘度对其喷雾造粒粉料性质影响。结果表明：氧化锆料浆含固量是喷雾造粒（ＳＤ．）粉料填充密度的主要控制因素，高含固量料浆能得到高填充密度喷雾造粒粉料，且其颗粒显微结构相对致密；随着ＺｒＯ２料浆含固量、粘度增加，喷雾造粒粉料平均粒径增大，粗颗粒含量增多，细颗粒含量减少。     

水基SiC料浆的分散稳定机制及喷雾造粒

以去离子水为液体介质,引入有机添加剂,配制水基SiC悬浮料浆,研究了水基料浆的分散稳定机制及其喷雾造粒行为,分析了有机添加剂和固相含量对料浆流变性能、造粒粉粒径分布及成型性能的影响机制.结果表明:当料浆pH≥10时,水基碳化硅料浆的分散性和稳定性较好,料浆具有剪切稀化的非Newton体特性:当加入0.2%(质量分数,下同)四甲基氢氧化铵、2.0%聚乙烯醇和1.0%聚乙二醇时,料浆黏度较小:固相含量为50%水基料浆喷雾造粒后,造粒粉的流动性、填充性能及成型性能明显提高,但球状造粒粉需要在一定成型压力下才能完全破碎.     

奶粉的喷雾冷冻干燥研究

研究开发了实现喷雾冷冻干燥工艺的装置,并以奶粉为物料,进行了试验研究。结果表明,料液可以在-40～-30℃实现快速冷冻,且采用该喷雾冷冻干燥装置可将干燥时间从原来真空冷冻干燥的48h缩短为10h。最后,对获得的干燥产品进行了粉体形态的测试和分析。     

喷雾干燥法生产麦胚粉的工艺研究

文章以产品的溶解时间为主要指标,通过单因素及正交优化试验,研究了压力式喷雾干燥法生产麦胚粉的工艺以及喷雾压力、进风温度、物料浓度等工艺参数对冲调性能的影响.试验表明,当喷雾压力为0.9 MPa,进风温度180 ℃、料液浓度25%时,所得的麦胚产晶具有较好的冲调性.     

并流喷雾干燥产品湿含量的控制

拟定了以料浆喷雾量FL为调节变量,控制气体出塔温度Tgf的反馈控制结构;建立了以Tgf为主要状态变量的过程动态模型,用于撞击流反应-沉淀法制超细白炭黑生产系统中喷雾干燥产品湿含量的控制。     

枯草芽孢杆菌BSD-2菌株喷雾干燥工艺优化

为研制生物农药新剂型,利用喷雾干燥法制备浓缩枯草芽孢杆菌BSD-2菌粉。以集粉率和抑菌活性为指标,确定最佳喷雾干燥工艺条件。在发酵液中加入15%β-环糊精作为填料,最佳入口温度为170℃,料液温度为30℃,热风量为20 m3/h,入料流量为15 m L/min。此条件下喷雾集粉率达到25.4%,效价保留率为66%,BSD-2菌体存活率为75%。     

不同结构羟基磷灰石微球的制备及相关机理分析

利用喷雾干燥法成功制备具有实心、多孔和空心结构的羟基磷灰石(hydroxyapatite,HA)微球,简要分析不同结构HA微球的形成机理.用扫描电镜观察产物的微观结构和表面形貌发现:将HA料浆直接喷雾十燥可以获得形状规则的实心微球;向料浆中加入明胶溶液后再喷雾干燥,随后经高温煅烧可以获得孔隙率较高的多孔微球:向料浆中加...     

喷雾干燥的研究进展

介绍了国内外喷雾干燥领域的最新研究进展,阐述了喷雾冷冻干燥、超临界喷雾干燥等方面的研究结果,探讨了关于喷雾干燥过程数学模拟的研究方法和结论,总结、归纳并提出了目前国内外较新的关于喷雾干燥的研究课题和方向。     

以水玻璃为硅源喷雾干燥制备SiC前驱体

以廉价的水玻璃和炭黑为原料,通过制备均匀混合的前驱体,利用碳热还原反应合成出超细SiC粉体。比较研究了前驱体喷雾干燥与搅拌干燥两种制备方法对体系碳热还原反应的影响,重点考察了喷雾干燥制备过程中主要工艺参数对前驱粉体密度及收率的影响。结果表明:喷雾制备的前驱体具有更高的反应活性,在1550℃下反应2h就可使SiO2转化率达到89.4%,搅拌干燥制备的前驱体转化率只有65.2%。喷雾干燥过程中,适当提高进口温度、喷雾头转速并降低料液的固体含量,可获得高收率、高产率的前驱粉体,利于整个制备工艺生产效率及产率的提高。     

废酸喷雾浓缩装置的设计及制作原理

针对目前钛白废酸回收利用工艺存在的不足,提出了喷雾浓缩钛白废酸的技术方案,该技术方案具有传热效率高、设备费用低和不易堵塞的优点。根据喷雾干燥原理,探索了喷雾浓缩原理,为喷雾浓缩原理提供理论依据。研制出的喷雾浓缩装置可以一级将钛白废酸由质量分数为20%浓缩至80%以上,浓缩效果明显,具有较好的推广应用价值。     

DRYING WOOD: A REVIEW - PART I

ABSTRACT

This paper reviews the technology of wood drying and recent developments in the field. The importance of drying is reviewed first. Then the fundamentals of wood properties as they relate to drying are discussed, including how water is held in wood, how it moves through wood, and how drying stresses that lead to drying defects develop. Traditional drying technology for lumber, veneer, and heavy timbers is then presented. With this background, the discussion moves to recent developments in drying technology that have been implemented commercially, such as high-temperature drying, low-temperature drying, continuously rising temperature drying, vacuum drying, and advances in process control. Finally, a discussion is presented on drying technology of the future. This topic describes processes that offer potential improvements in drying technology, but are still in the research and development stage.     

碳酸钙干燥设备概况与发展

对碳酸钙（轻钙，重钙，纳米钙，专用钙等）的干燥及其有关设备的现状和发展作了回顾，并就轻钙、重钙、纳米钙等干燥效率的提高、设备的改进以及组合干燥的应用实际效果作了阐述。     

DRYING WOOD: A REVIEW - PART I

This paper reviews the technology of wood drying and recent developments in the field. The importance of drying is reviewed first. Then the fundamentals of wood properties as they relate to drying are discussed, including how water is held in wood, how it moves through wood, and how drying stresses that lead to drying defects develop. Traditional drying technology for lumber, veneer, and heavy timbers is then presented. With this background, the discussion moves to recent developments in drying technology that have been implemented commercially, such as high-temperature drying, low-temperature drying, continuously rising temperature drying, vacuum drying, and advances in process control. Finally, a discussion is presented on drying technology of the future. This topic describes processes that offer potential improvements in drying technology, but are still in the research and development stage.     

Processes for controlling the structure and texture of dehydrated banana

This study is about how to control the microstructure of dehydrated banana during drying by a multi-flash drying process. The influence of different drying methods and process variables on the formation of fruit microstructure and texture were evaluated. These processes included a conductive multi-flash drying process, conductive multi-flash drying combined with classical vacuum drying, convective drying in an oven, and vacuum drying. Density, porosity, and shrinkage of dehydrated fruit were strongly influenced by the drying process. Results showed that it is possible to control the porous structure of dehydrated banana by choosing the correct dehydration process.     

工业干燥的革新现状与研发需求

在过去的30年,全球干燥研发活动呈现出快速增长趋势。尽管热力干燥在几乎所有主要工业生产部门都是一个重要的单元操作,干燥基础和工业应用研究却是在上世纪70年代早期发生能源危机后才开始兴起。随后石油价格下跌,但人们已认识到改善干燥操作以节省能源、提高产品质量、减少环境影响的重要性;最近几年更增强了这种意识。新的干燥技术、更好的操作措施和干燥机控制策略、先进和可靠的放大方法,已经帮助生产出低成本和高质量的干燥产品。由于没有一个普遍适用的干燥理论,多数干燥数学模型仅适用于特定的产品和设备。本文将讨论革新在不同工业干燥部门如纸张、木材、农产品、废弃物等所发挥的作用,概述过去30年干燥研究的进展和面对的挑战,指出一些需要继续研究努力的干燥领域,举例讨论通过数学模型强化干燥器设计的革新,同时强调指出,学术界与工业界紧密互动是未来10年干燥研发获得成功的关键。     

Image Analysis,Homogenization, Numerical Simulation and Experiment as Complementary Tools to Enlighten the Relationship between Wood Anatomy and Drying Behavior

Abstract

This paper has been written for a special issue devoted to the works done in France in the field of drying. Therefore, it aims, through numerous examples, to show the spirit which initiates and guides the research work of the Forest Products Unit at ENGREF : how more and more microscopic information can be included in the study of the drying process ?

Two steps are involved :

?microscopic observation and experiments to predict the macroscopic properties

?use of the macroscopic properties (the previous step + experiments carried our at the macroscopic scale) to predict the drying behavior.

In this approach, each prediction comes from a model, that means assumptions, formulations, calculations and then validation.

Several tools (image analysis, homogenization, measurement of microscopic and macroscopic properties, numerical simulation of heat and mass transfer, refined drying experiments) are used to study the drying of wood.     

Refractance Window Dehydration Technology: A Novel Contact Drying Method

Refractance Window® (RW) system is a novel drying method for converting liquid foods and other related biomaterials into powders, flakes, or sheets with added value. In this system, purees or juices prepared from fruits, vegetables, or herbs dry in short times, typically 3-5 min, resulting in products with excellent color, vitamin, and antioxidant retention. The RW drying systems are simple and relatively inexpensive when compared with freeze drying, which usually needs large installations to be economical. In RW drying systems thermal energy is transferred from hot water to a film of puree or juice spread thinly on a plastic conveyor belt. These drying systems operate at atmospheric pressure and are used for commercial production of scrambled egg mix, avocado powder, high carotenoid-containing algae, herbal extracts and human nutrition supplements, and food ingredients, as well as dried fruits and vegetables. This article presents the principle of Refractance Window® drying and highlights some results that show its potential and how it compares with other dryers for processing fruits, vegetables, and other heat-sensitive products.     

Image Analysis, Homogenization, Numerical Simulation and Experiment as Complementary Tools to Enlighten the Relationship between Wood Anatomy and Drying Behavior

This paper has been written for a special issue devoted to the works done in France in the field of drying. Therefore, it aims, through numerous examples, to show the spirit which initiates and guides the research work of the Forest Products Unit at ENGREF : how more and more microscopic information can be included in the study of the drying process ?

Two steps are involved :

•microscopic observation and experiments to predict the macroscopic properties

•use of the macroscopic properties (the previous step + experiments carried our at the macroscopic scale) to predict the drying behavior.

In this approach, each prediction comes from a model, that means assumptions, formulations, calculations and then validation.

Several tools (image analysis, homogenization, measurement of microscopic and macroscopic properties, numerical simulation of heat and mass transfer, refined drying experiments) are used to study the drying of wood.     

Simulation of Liquid Diffusion-Controlled Drying of Shrinking Thin Slabs Subjected to Multiple Heat Sources

Abstract

Although a detailed mathematical model incorporating all physical mechanisms of moisture and heat transfer in the material would yield valuable design information, it is not feasible to do this on a routine basis for the design of dryers. A simple liquid diffusion model was developed in the present study to quantitatively assess the influence of various operating parameters of engineering interest in drying of heat-sensitive materials. Heat of wetting, temperature, and moisture dependent effective diffusivity and thermal conductivity, changes in product density and drying-induced ideal shrinkage of the product are considered in this model. The effects of combining convection with conduction, radiation, and volumetric heating using a microwave field are simulated in view of the increasing interest in multimode heat input drying processes. Numerical results are reported on drying of potato slices to demonstrate how the moisture and temperature profiles as well as drying performance are affected by multi-mode heat input. Effects of key parameters e.g., drying air velocity, temperature, relative humidity, and product thickness are computed and discussed.     

Effects of operating parameters of impinging stream dryer on parboiled rice quality and energy consumption

Abstract

It is very important to know how operating condition of a coaxial impinging stream dryer affects the drying time, parboiled rice quality and energy consumption. The drying temperature, parboiled paddy feed rate, drying air velocity and impinging distance were experimentally investigated. Increases in drying temperature and air velocity and a decrease in paddy feed rate provided higher evaporation rate whilst impinging distance, ranging from 5 to 13?cm, did not affect the evaporation rate. Collision between kernels within the impinging zone caused the hull’s lemma splitting from the kernel and the percentage of the split kernel strongly depended on the air velocity and feed rate. The acceleration in the rate of drying by changing the above operating parameters did not affect the head rice yield. In addition, the collision of kernels also did not influence the head rice yield since the mechanical properties of rice are strengthened during steaming step in the parboiling process. However, the change of head rice quality was only governed by the moisture content after drying. The total energy consumption including electricity and heat was strongly depended on the air velocity and feed rate whilst it was slightly changed with the drying temperature. From the present study, it was recommended that the parboiled paddy should not be dried below 25% d.b. and the highest temperature that could possibly be used was 190?°C and the inlet air velocity should not be below 15?m/s.