ENHANCEMENT OF THE PROCESSES OF TRANSFER OF HEAT IN A DIABATIC FRACTIONATING COLUMN

Raising energy effi ciency in the course of heat- and mass-transfer processes in column fractionating apparatuses is one topical problem of applied science and industry. Consideration has been given to a method of raising energy effi ciency during the rectifi cation of liquid mixtures due to the diabatization of the columns, that consists in installing built-in heat exchangers. The aim of the research is to determine thermal characteristics of the fl ow with the classical method of enhancement of heat transfer: fi nning the tubes externally. A mathematical description of the condensation of ascending vapor on the horizontal surface of fi nned tubes was developed. As a result of the research, the authors have determined heat outputs, temperatures of the heat-transfer agent at exit from a tubular dephlegmator, fl ow rates of cooling water, heat-transfer coeffi cients, linear coeffi cients of heat transfer, and thermal resistances of heat transfer with fi nned and smooth dephlegmator tubes on each tray in the rectifying section of the fractionating column. Results of theoretical investigations have shown that enhancing the processes of transfer of heat when the exterior tube surface is fi nned made it possible to increase heat fl uxes in the dephlegmators to 3.74 times. It has been shown that the use of heat-transfer enhancers in the form of fi nning on the outside of dephlegmator tubes allows equalizing thermal heat-transfer resistances. It has been established that the investigated structure of a tubular dephlegmator with fi nned tubes makes it possible to raise the Murphree effi ciency of the valve tray by 7.7%.
Raising energy effi ciency in the course of heat- and mass-transfer processes in column fractionating apparatuses is one topical problem of applied science and industry. Consideration has been given to a method of raising energy effi ciency during the rectifi cation of liquid mixtures due to the diabatization of the columns, that consists in installing built-in heat exchangers. The aim of the research is to determine thermal characteristics of the fl ow with the classical method of enhancement of heat transfer: fi nning the tubes externally. A mathematical description of the condensation of ascending vapor on the horizontal surface of fi nned tubes was developed. As a result of the research, the authors have determined heat outputs, temperatures of the heat-transfer agent at exit from a tubular dephlegmator, fl ow rates of cooling water, heat-transfer coeffi cients, linear coeffi cients of heat transfer, and thermal resistances of heat transfer with fi nned and smooth dephlegmator tubes on each tray in the rectifying section of the fractionating column. Results of theoretical investigations have shown that enhancing the processes of transfer of heat when the exterior tube surface is fi nned made it possible to increase heat fl uxes in the dephlegmators to 3.74 times. It has been shown that the use of heat-transfer enhancers in the form of fi nning on the outside of dephlegmator tubes allows equalizing thermal heat-transfer resistances. It has been established that the investigated structure of a tubular dephlegmator with fi nned tubes makes it possible to raise the Murphree effi ciency of the valve tray by 7.7%.
Author:  I. N. Madysheva, A. O. Mayasova
Keywords:  diabatic rectifi cation, fi nning of tubes, heat transfer, thermal resistance
Page:  1451