CAD OF THERMOSYPHON REBOILER

Abstract

The present investigation pertains to theoretical study of CAD of Thermosyphon Reboilers. Basically it deals with the development of CAD of Vertical and Horizontal Thermosyphon reboilers. It also includes the comparison of present investigation with Kern's method. In the last it prescribe the effect of design variable namely recirculation ratio, tube dimensions, tube pitch and tube pattern on the tube side heat transfer coefficient and pressure drop in the case of vertical thermosyphon reboiler and shell side heat transfer coefficient and pressure drop in the case of horizontal thermosyphon reboiler. Using the method proposed by Frank [4], Gerald [5], Martin [12], Orrell [14], Salim [18] a design algorim has been developed for the CAD of thermosyphon reboiler. Based on this algorithm a computer program has been developed and design has been obtain for the vaporization of pure Butane in vertical thermosyphon reboiler and Naphtha in horizontal thermosyphon reboiler. Recirculation ratio requires for both the cases have been compared with the Kern's method. It has been found that Kern's method provide higher recirculation ratio than present investigation. This is due to the fact that Kern's method consider only single phase resistance to flow where as in present investigation all the resistance have been incorporated. Hence Kern's method 30 to 40 % over design the thermosyphon reboiler. Effect of design variable namely recirculation ratio, tube pitch, tube length, outer diameter of tube, shell diameter and tube pattern on the tube side heat transfer coefficient and pressure drop in the case of vertical thermosyphon reboiler and shell side heat transfer coefficient and pressure drop in case of horizontal thermosyphon reboiler have been studied. It has been found that increase in recirculation ratio and tube length increases the tube side heat transfer coefficient and pressure drop in case of vertical thermosyphon reboiler. Further, it has been found that shell side heat transfer coefficient decreases with the increase of recirculation ratio, increase of shell diameter and increase of tube pitch, where as shell side pressure drop increases with the increase in recirculation ratio, decrease in shell diameter and decrease in tube pitch in the case of horizontal thermosyphon reboiler. Shell side pressure drop and heat transfer coefficient has been found to be more in the case of triangular tube pattern in horizontal thermosyphon reboiler.