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Complex methods of drying medical preparations
Heat Recover)" St'stems Vol. 5, No. 50 pp. 463--467, 1985
0198-7593/85 $3.00 + .00 Pergamon Press Ltd
Printed in Great Britain
SUMMARIES OF OTHER CHISA CONGRESS PAPERS OF INTEREST A considerable number of papers in the sessions dealing with "Chemical Equipment" at the CHISA Congress were either not formally presented or given in poster sessions in forms not suitable for inclusion here. Summaries written by the authors have been published for conference attendees, however, and a selection of the most relevant as far as heat recovery is concerned are given below. It is suggested that readers wishing to obtain full copies of the papers, or further data, contact the authors of the papers concerned. Sessions of principal interest are those on drying and heat transfer apparatus. THEORETICAL AND EXPERIMENTAL STUDY OF SPRAY DRYING PROCESSES A. A. DOLtNSKn and G. K. IVANITSKH Inst. Eng. Thermophys., Ukr. Acad. Sci., Kiev, USSR Problems and ways of studying aerodynamics, hydrodynamics and heat- and mass-transfer in spray drying units are discussed in the paper. It is pointed out that internal processes of heat and mass transfer taking place in a separate panicle have a decisive effect on the character and the total intensity of high temperature dehydration of dispersed solutions. The physical mechanism of internal processes related to thermophysical and kinetic properties of the humid material and operating conditions of the spray drying plants is analysed. The paper presents the results of combined use of methods of mathematical and experimental simulation for describing the kinetics of drying the solutions, suspensions and past-like materials. The methods of controlling the internal processes of transfer and structure formation in a separate particle are discussed in order to optimise spray drying units operation. SIMULATION OF A ROTARY DRYER FOR FERTILIZERS A. HALLSTROEM Dept. Chem. Eng., Lurid Univ., Lurid, Sweden For the purpose of process optimization, a mathematical model based on the shrinking core concept had earlier been developed. In this work the model is used for simulation of a full-scale process. The data that are needed in the model are, in addition to the characteristics of the dryer, sorption equilibrium data and a batch-wise drying curve. Measurements on the industrial process have been performed. The results from the simulations are compared with the measured data. Simulation is used to show the effects of change in temperature, air-to-solid ratio, and residence time. Alterations in the process are suggested that would lead to improved energy economy. COMPLEX METHODS OF DRYING MEDICAL PREPARATIONS P. S. KuTs, N. V. FEDOROVlCH, S. M. l~pm~rrsEv^ and K. G. CHIZHIK Heat Mass Transfer Inst., Minsk, USSR In the production of medical preparations heat and mass transfer processes are widely used. Among them drying takes an important place since it is the most energy and time consuming process basically determining the quality of end products. The available methods of drying chemical and pharmaceutical preparations are analysed. It is shown that the most profitable are continuous complex procedures which allow a number of 463
464
Summaries of other CHISA papers
important interdependent processes including raw material treatment, granulation, milling and refinement to be performed simultaneously. Those are complex drying procedures developed at the Heat and Mass Transfer Institute, BSSR Academy of Sciences certified as USSR A.C. No. 350513, BI 28, 1972; A.C. No. 733728, BI 18, 1980; A.C. No. 958813, BI 34, 1982; A.C. No. 958814, BI 34, 1982. They involve combined hydrodynamics of falling fluidised bed drying and convection-radiation heat supply the latter implying several operations (mixing, granulation and drying) in one apparatus. Based on the suggested procedures, pilot and then commercial installations have been designed which are now in mass production, A.C. No. 5785348, BI No. 40, 1977, USSR. It is shown that the apparatus of continuous operation of the Heat and Mass Transfer Institute systems are superior in their technological and economical factors to the dryers applied in the field. The theoretical and experimental results enable one to conclude on the reliable and promising application of the complex continuous-operation and dryers of the Heat and Mass Transfer Institute system not only in medical but also in chemical, food and other industries.
THE SURVEY OF THE PROCESS AND CONNECTION A R R A N G E M E N T FOR THE SOLVENT RECOVERY R. T6R6S, E. VASANrrS-VERGAand T. VIRAG Res. Inst. Techn. Chem., Hung. Acad. Sci., Budapest, Hungary For the recovery of solvent vapours being released during drying of materials containing solvent the condensation in a closed cycle has been studied. The drying has been performed in a spouted-bed drier, where the drying medium emerging from the dryer is recirculated into the dryer by a closed cycle after the condensation of its solvent vapour. For the realisation of the condensation and for the heating of the drying medium again to the necessary drying temperature of a heat pump with a compressor (0.9 kW power consumption) has been constructed (also in the research institute for Technical Chemistry of Hungarian Academy of Sciences) and built in the closed cycle of the drying medium. The developed process and connection arrangement for the recovery of the solvent content and also the heat of condensation of the drying medium is given in detail. The process taking place in the connected system of spouted-bed dryer and heat pump can be clearly followed on the presented l - x diagram. For the model substances like carbon tetrachioride and ethanol solvents and nitrogen inert gas in the closed cycle have been used. The efficiency of the solvent recovery has been about 70-95%. This shows the economical application of the heat pump for the solvent recovery. The operation in a closed cycle has an environmental advantage, too, because no solvent is emitted into the atmosphere.
SPRAY COOLING OF HOT SURFACES K . BAUCKHAGE
Univ. Bremen, Bremen, FRG Spray cooling by water droplets plays an important role in the steel and metal-works industries. The heat flux density at a hot surface can be strongly influenced by the mass velocity of the atomised water, especially at high surface temperature (above the burnout point). Measurements of the local heat transfer coefficients give a true picture of local water-massvelocities beyond the spray nozzle, if the size- and velocity-distributions of the droplets are in agreement with the required impulse for destroying (a) the vapour film of the film boiling regime and (b) the sublayer of vapour between droplets and hot surface. Experimental results will be exposed and the consequences for spray cooling will be discussed.
0198-7593/85 $3.00 + .00 Pergamon Press Ltd
Printed in Great Britain
SUMMARIES OF OTHER CHISA CONGRESS PAPERS OF INTEREST A considerable number of papers in the sessions dealing with "Chemical Equipment" at the CHISA Congress were either not formally presented or given in poster sessions in forms not suitable for inclusion here. Summaries written by the authors have been published for conference attendees, however, and a selection of the most relevant as far as heat recovery is concerned are given below. It is suggested that readers wishing to obtain full copies of the papers, or further data, contact the authors of the papers concerned. Sessions of principal interest are those on drying and heat transfer apparatus. THEORETICAL AND EXPERIMENTAL STUDY OF SPRAY DRYING PROCESSES A. A. DOLtNSKn and G. K. IVANITSKH Inst. Eng. Thermophys., Ukr. Acad. Sci., Kiev, USSR Problems and ways of studying aerodynamics, hydrodynamics and heat- and mass-transfer in spray drying units are discussed in the paper. It is pointed out that internal processes of heat and mass transfer taking place in a separate panicle have a decisive effect on the character and the total intensity of high temperature dehydration of dispersed solutions. The physical mechanism of internal processes related to thermophysical and kinetic properties of the humid material and operating conditions of the spray drying plants is analysed. The paper presents the results of combined use of methods of mathematical and experimental simulation for describing the kinetics of drying the solutions, suspensions and past-like materials. The methods of controlling the internal processes of transfer and structure formation in a separate particle are discussed in order to optimise spray drying units operation. SIMULATION OF A ROTARY DRYER FOR FERTILIZERS A. HALLSTROEM Dept. Chem. Eng., Lurid Univ., Lurid, Sweden For the purpose of process optimization, a mathematical model based on the shrinking core concept had earlier been developed. In this work the model is used for simulation of a full-scale process. The data that are needed in the model are, in addition to the characteristics of the dryer, sorption equilibrium data and a batch-wise drying curve. Measurements on the industrial process have been performed. The results from the simulations are compared with the measured data. Simulation is used to show the effects of change in temperature, air-to-solid ratio, and residence time. Alterations in the process are suggested that would lead to improved energy economy. COMPLEX METHODS OF DRYING MEDICAL PREPARATIONS P. S. KuTs, N. V. FEDOROVlCH, S. M. l~pm~rrsEv^ and K. G. CHIZHIK Heat Mass Transfer Inst., Minsk, USSR In the production of medical preparations heat and mass transfer processes are widely used. Among them drying takes an important place since it is the most energy and time consuming process basically determining the quality of end products. The available methods of drying chemical and pharmaceutical preparations are analysed. It is shown that the most profitable are continuous complex procedures which allow a number of 463
464
Summaries of other CHISA papers
important interdependent processes including raw material treatment, granulation, milling and refinement to be performed simultaneously. Those are complex drying procedures developed at the Heat and Mass Transfer Institute, BSSR Academy of Sciences certified as USSR A.C. No. 350513, BI 28, 1972; A.C. No. 733728, BI 18, 1980; A.C. No. 958813, BI 34, 1982; A.C. No. 958814, BI 34, 1982. They involve combined hydrodynamics of falling fluidised bed drying and convection-radiation heat supply the latter implying several operations (mixing, granulation and drying) in one apparatus. Based on the suggested procedures, pilot and then commercial installations have been designed which are now in mass production, A.C. No. 5785348, BI No. 40, 1977, USSR. It is shown that the apparatus of continuous operation of the Heat and Mass Transfer Institute systems are superior in their technological and economical factors to the dryers applied in the field. The theoretical and experimental results enable one to conclude on the reliable and promising application of the complex continuous-operation and dryers of the Heat and Mass Transfer Institute system not only in medical but also in chemical, food and other industries.
THE SURVEY OF THE PROCESS AND CONNECTION A R R A N G E M E N T FOR THE SOLVENT RECOVERY R. T6R6S, E. VASANrrS-VERGAand T. VIRAG Res. Inst. Techn. Chem., Hung. Acad. Sci., Budapest, Hungary For the recovery of solvent vapours being released during drying of materials containing solvent the condensation in a closed cycle has been studied. The drying has been performed in a spouted-bed drier, where the drying medium emerging from the dryer is recirculated into the dryer by a closed cycle after the condensation of its solvent vapour. For the realisation of the condensation and for the heating of the drying medium again to the necessary drying temperature of a heat pump with a compressor (0.9 kW power consumption) has been constructed (also in the research institute for Technical Chemistry of Hungarian Academy of Sciences) and built in the closed cycle of the drying medium. The developed process and connection arrangement for the recovery of the solvent content and also the heat of condensation of the drying medium is given in detail. The process taking place in the connected system of spouted-bed dryer and heat pump can be clearly followed on the presented l - x diagram. For the model substances like carbon tetrachioride and ethanol solvents and nitrogen inert gas in the closed cycle have been used. The efficiency of the solvent recovery has been about 70-95%. This shows the economical application of the heat pump for the solvent recovery. The operation in a closed cycle has an environmental advantage, too, because no solvent is emitted into the atmosphere.
SPRAY COOLING OF HOT SURFACES K . BAUCKHAGE
Univ. Bremen, Bremen, FRG Spray cooling by water droplets plays an important role in the steel and metal-works industries. The heat flux density at a hot surface can be strongly influenced by the mass velocity of the atomised water, especially at high surface temperature (above the burnout point). Measurements of the local heat transfer coefficients give a true picture of local water-massvelocities beyond the spray nozzle, if the size- and velocity-distributions of the droplets are in agreement with the required impulse for destroying (a) the vapour film of the film boiling regime and (b) the sublayer of vapour between droplets and hot surface. Experimental results will be exposed and the consequences for spray cooling will be discussed.