Showing papers in "Drying Technology & Equipment in 2007"

Thermal drying technologies: new developments and future r&d potential

Abstract: Thermal dehydration processes are highly energy-intensive and are found in almost all industrial sectors, accounting for 10 to 20 percent on national industrial energy consumption in developed countries. With escalating energy costs and need to mitigate environmental pollution due to emissions from combustion of fossil fuels, it is increasingly important to develop innovative drying technologies. Furthermore, drying also affects quality of the dried product due to physical and/or chemical transformations that may occur during the heat and mass transfer operation. With tens of thousands of products that are dried in hundreds of dryer types, it is a formidable task indeed to develop design and scale-up procedures of wide applicability. Attempts have been made over the past three decades to make fundamental and applied contributions to transport phenomena and material science aspects in drying of various forms of wet solids, pastes and liquids. This presentation will attempt to summarize the state-of-the-art as far as theoretical understanding of drying processes and provide examples of some new technologies being developed. Opportunities for challenging fundamental and modeling studies to enhance drying technologies will be identified. Illustrative results will be presented to show how mathematical modeling of spray, spouted bed and heat pump dryers can be utilized to develop new conceptual designs and to optimize operating conditions as a cost-effective route to intensify innovation in thermal dryer design.

Experimental Study on Sludge Drying Rate And Energy Consumption

Abstract: Variation of moisture content,air parameters (temperature,relative humidity),and parameters of heat pump (parameters of refrigerant,dehydration efficiency of heat-pump,and energy recycling rate ) were experimental studied on sludge drying with a minitype heat-pump dryer. Emphatically. The drying velocity,energy recycling rate and influencing factors were analyzed. The results showed that after preheated by exterior heat resource,temperature within kiln can averagely reach 63℃,the maximum temperature is 71℃ during sludge drying which the heat is recycled from heat pump only. Temperature within chamber depended on the temperature of air pass through the condenser of heat pump,which is influenced by state of refrigerant. Sludge drying velocity increases as the temperature of air rise and the relative humidity decrease. Average drying velocity during the MC range of 42.6%～18.74% is 0.123%/m. The result showed a great recycling effect,and energy recycling rate increase with the increase of discharge capacity. Average energy recycling rate is 39.1%,the maximum and minimum value is 48.9% and 23.6%,respectively,which is corresponding to max and min discharge capacity stage respectively.

Effect of Different Desalting Methods on Quality Changes of Dehydrated Salicornia Bigelovii Torr

Abstract: In this paper, the quality changes of the dehydrated Salicornia bigelovii Torr treated by clear water immersion, vacuum infiltration and ultrasonic treatment were inverstigated, and the quality parameters were compared on the basis of salt content, Vc and chlorophyll contents, sensory assess before or after rehydration. The experiment results have shown that by vacuum infiltration the effect of desalting and the maximum quality characteristics of produce was achieved.

Induced Discoloring Process of Buerger Maple Under Drying Conditions

Abstract: Buerger Maple (L. formosana Hance) is a kind of wood that is easily discolored. This research tries to obtain satisfied color and a vast prospect in the utilization of Buerger Maple by induced discoloration. This paper analyzes the mechanism of induced discoloring of Buerger Maple by means of the analysis of visual physical parameter, the infrared spectrum (IRS) and the scanning electron microscope (SEM) under different drying conditions. The result shows that it is feasible to induce discoloration during the drying process. The varied tendency of wood color trends to red and fuscous colors during inducing discoloration of Buerger Maple. The induced discoloring mechanism is: ①the high temperature and humidity accelerates the oxidation reaction of polyphenol, leuco-fancy pigment and tannin, which changes the wood to the red color; ②the hydroxy (-OH) is oxidized and the carbonyl (-C=O), carboxyl (-COOH), ester and ketone groups are formed during the high temperature steaming, which results in wood piece discoloration.

Industrial Drying: Innovation, Situation and Developing Needs

Abstract: Although a truly ancient unit operation found in almost all industrial sectors, significant RD effort in this field started just about three decades ago. Possibly as a result of the energy crisis of the early 70's which spawned the IDS series in 1978, there has been a remarkable increase in the RD effort devoted to understanding drying fundamentals and applying them to improving the performance of traditional drying techniques as well as developing innovative ones. This presentation will attempt to summarize my personal thoughts on the process of innovation and how it has been and will be applied to drying RD. The need for RD in the multi- and inter-disciplinary area of drying in the face of severe competition for human and financial resources from the newer "extreme engineering" applications will be emphasized. Some areas suitable for future development will be identified. The need for development of a new generation of highly qualified research personnel in drying and the importance of industry-academia interaction should be recognized to continue to enhance our knowledge of the complex field of solids drying.

Spay Drying: Functionalization of Target Product

Abstract: This paper presented the development of spray drying technology and indicated that the importance of spay drying on preparation of functional products. One of development trend is the Preparation functional materials by spray drying .In this paper some of the method are introduced in detail. Especially, the preparation of microcapsules, composite particles, ultrafine particles and the general principle of spray pyrolysis was described.

Studies on the Moisture Adsorption Isotherms of Dried Honey Prepared by Microwave-Vacuum Drying

Abstract: The Method of weighing in static state was applied for dried honey to obtain adsorption equilibrium moisture content. Then, adsorption isotherms were attained and the adsorption law was discussed. Simulation studies for comparing moisture adsorption experiments for dried honey of six conventional adsorption models applying in food under different temperature conditions showed that GAB model could be moisture adsorption model of dried honey. In addition, coefficients of this model were also determined.

Effect of Different Drying Technology on Quality of Astragalus Water Extract

Abstract: To develop the new drying technology for the condensing or dehydration of solvent extract of Chinese Herb Medicine (CHM),drying experiments of water extract of Astragalus were carried out. 4 different techniques,microwave drying,hot-air drying,vacuum drying and freeze-drying,were discussed in this paper. The micro-structure characteristics of samples were characterized by micrograph technique in the dimension of micron and nanometer,and the content of Astragalus polysaccharide (APS) of the samples were tested by ultraviolet spectrophotometer. The result shows that the dehydrated water content from the extract at 1h by microwave drying is almost the same as that at 4h by other 3 drying techniques. The microstructure characteristics of the dried sample by different drying techniques are related to the dehydration mechanism and its quality. The APS content of sample by microwave drying is little more than that by other 3 drying techniques. Therefore,the microwave drying technology can be used for the concentration and dehydration of CHM with the advantage of shortened drying time and better preservation of active ingredients

Research Progress on the Energy Reduce of Open-Type Air Drying Process of Vegetables

Abstract: In Open-Type Air Drying(AD) process, the equipment is cheap and its operation and management are easy, so it is still widely used in domestic vegetables drying industry. But it takes a high proportion of energy consumption. Studies on energy conservation are needed and important. The energy conservation can be reduced in following aspects, ①drying methods, ②optimization of the process, ③dryer's improving, ④waste-air recycling and ⑤application of regenerative energy.