摘要:

The use of computers to perform simulation of chemical engineering processes has lead to the development of software tools that Perform most tedious computations in the field of process analysis and design. The most popular Structures regarding process simulation of conventional and specialized processes are analyzed properly by considering the basic parts of commercial programs. Computational procedures. graphical aspects. management of properties database are outlined. Modeling aspects of drying technology regarding simulation are summarized and classified. The need for specialized software and development efforts in the field of commercial dryers simulation are enlohasized and nppropriately addressed. Moderm aspects. such as obiectoriented programming in simulation of industrial dryers are suitably presented and various case studies are used to indicate the effectiveness of modern simulation methods in the field of dryers operation.

ISSN:0737-3937    

DOI:10.1080/07373939608917137

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper is to review the works on strains and suesses in materials during drying.The strains and suesses are caused when temperature and moisture gradients are generated in mterials whose volume changes with heating and moisture removal. In such materials. failure and irregular deformion may be generated which affect considerably the qudity of the products after drying. In the first part. modeling procedure is introduced for the analysis of the strain-stress behavior in elaslic. viscous and visccelastic materials combined with heat and moisture transfer. An overview of the works on swains and stresses and drying characteristics are presented for malerials such as porous media. clay. sol-gels. agricultural products and foods in the second part. There are some materials that show both elasticity of the solid phase and viscosity of the fluid phase ( water or solvena∥ or viscoelasticiry. The suesses are often correlated with a suction pressure of fluids in pores and the flow rate is based on Dacy's equation for the elastic and viscous tnedia and a kind of viscoelastic media. The general canstitulive equalions. for suains and svesses are often analyzed with the stain behavior given by a function of moisturr for some media ai well. The emohasis is on the inuoduclion of comprehensive criteria for undersunding the problems of strain and stress development in materials subjected to drying.

ISSN:0737-3937    

DOI:10.1080/07373939608917138

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The influence of the recovery system and other system parameters upon drying selectivity was studied in a closed-cycle dryer. A continuously-worked unit consisting of a single stage dryer and a ondenser was simulated. In the dryer, a thin solid wetted with a liquid mixture was dryed in contact with an inert gas flowing either parallelly or as an impinging jet Partial recycle of the exhaust gas was allowed. Two recovery systems were studied, a scrubber condenser and an indirect condenser. Both drying and condensation were described by a mathematical model considering a s-phase-controlled process. The inlet liquid composition in the scrubber condenser has the greatest influence on drying selectivity. Degree of vapour recovery, recycle ratio and other operational parameters ffect selectivity and equipment dimensions in a variable extent. The combined use of these variables constitutes a powerful method to control selectivity. The present models may be useful to aid the optimization of the system with regard to product quality in gas-phase-conirolled processes.

ISSN:0737-3937    

DOI:10.1080/07373939608917139

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Dielectric heating is a term which covers both radio frequency (RF) and microwave systems. It has been used for industrial drying for many years because it has a number of advantages over other drying processes. These advantages include the volumetric dissipation of energy throughout a product, and the ability to automatically level any moisture variation within it. It is generally true to say that these techniques can only be justified in processes involving material of “high” value being processed in modest quantities but when combination with other fuel fired techniques there may be opportunities to broaden the range of applications. In addition to a desciption of current industrial applications, the theory of dielectric heating, the similarities and differences between RF and microwave are discussed together the effects of the dielectric roperties of a product on the design of the equipment

ISSN:0737-3937    

DOI:10.1080/07373939608917140

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The concept of steam drying originates from the mid of the last century. However, a broad industrial acceptance of the technique has so far not taken place. The paper deals with modelling the steam drying process and applications of steam drying with in certain industrial sectors where the technique has been deemed to hove special opponunities.

ISSN:0737-3937    

DOI:10.1080/07373939608917141

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Results of studies on cooling and drying of powdery and granulated material in a pulsed-fluid bed ( PFB) system with relocated gas stream presented here are related to hydrodynamics and kinetics of these processes. Generalized results in the form of dimensionless equations can be used to determine basic process parameters such as drying time, heat transfer coefficient, pulsed-fluidzation velocity. pressure drop, etc. Results of experimental investigations, supplemented with experiments carried out in a prototype industrial equipment, can be useful for dryer scale-up and are recommended for designing.

ISSN:0737-3937    

DOI:10.1080/07373939608917142

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Impinging jets are widely used throughout various industries. The nozzle designused most frequently for jet impingement is the in-line jet. There have been manyattempts at altering a jet's flow to increase its transport characteristics. The transportcharacteristics of two recently developed innovative and practical submerged impinging jets are described. Specifically, the heat and mass transfer characteristics of the Radial Jet Reattachment (RJR) nozzle and Self-Oscillating Jet Impinging Nozzle (SOJIN) are presented and cornoared lo the in-line iet nozzle. Both nozzles orovide high transport Coeficients. The RJR nozzle is for applications where'it is crucial to control the normal force on the imoinaement surface and those aoolications where space above the surface is to be minimized. The SOJIN offers an inexpensive modification to in-line nozzles in order to increase their transport properties. The SOJIN is exceptionally beneficial when standard in-line nozzles are required to work closer to the impingement surfaces than their optimal spacing.

ISSN:0737-3937    

DOI:10.1080/07373939608917143

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Artificial drying is an important step in processing of green crops in order to preserve their freshness and nutrients for longer time at relatively lower costs. Forage crops, tea and tobacco are the major green crops where the commercial drying is a major operation in their processing. Fresh green alfalfa at about 75 to 80% moisture is subjected to drying in different types of dryers.ln the case of alfalfa, the raw material consists of leaves, stems, chops and fine stems, each varying distinctly in their physical and structural characteristics. The moisture content is reduced from initial level to about 10%. The drying air temperatures range from 40 b 800°C; the lower temperatures are used inconveyor dryers whereas high temperatures are used in rotary drum drycn.The results on drying behavior, and changes in physico-chemical propedes during drying for components of green alfalfa over the temperature range of 40 m 800°C are presented in this paper. The optimum temperature for drying from the stand point of color and protein solubility was found to be 175°C.

ISSN:0737-3937    

DOI:10.1080/07373939608917144

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In designing cascading rotary dryers, it is important to size the flights correctly in order to ensure.

ISSN:0737-3937    

DOI:10.1080/07373939608902592

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor