Design and Simulation of a Shell and Tube Heat Exchanger for a Pyrolysis Reactor

Abstract

Global concern for climate change and greenhouse gases effect necessitates the promotion and development of an alternative source of energy which will drastically reduce global warming and ultimately pose lesser threat to climate change. Since the volatiles are composed of the condensable and non-condensable components, a heat exchanger is required to obtain bio-fuel from these volatiles. In this research heat exchanger was developed for optimum condensation of volatile vapour (pyro-gas) exiting in a reactor during pyrolysis process. Copper and stainless steel were selected for the development of heat exchanger tube and shell respectively. Mathematical equations were used in sizing and rating the shell and tube heat exchanger, thereby estimating the desired length, shell diameter and number of baffles. Computational Fluid Dynamic (CFD) simulation of the designed heat exchanger was done on the ANSYS software and the validation of the model was achieved by comparing the theoretical temperature with the temperature predicted from the simulation. Results from the theoretical and CFD simulation shows satisfactory similarity in terms of percentage deviation estimated as 4.68% for shell and 4.62% for tube respectively. Simulated percentage product yield for liquid (48.88% and 46.00%), and gas (9.36% and 29.12%) at 400oC and 600oC were slightly higher than the experimental values of liquid (47.00% and 44.00%), and gas (9.00% and 28.00%) at the same temperatures.  In conclusion, the designed heat exchanger can be developed and used for the existing reactor for efficient and effective condensation for improved bio-oil yield.