(228g) CFD Analysis of the Effect of Baffles On the Fluid Flow and Heat Transfer Inside the Shell of Cross-Flow Fixed Bed Reactor

Tubular fixed bed reactors are used for highly exothermic reactions and are one of the most important reactor types in the chemical and petrochemical industries. Uniform condition of heat transfer between the tubes is the key to the reactor design. In the present work, the numerical method was used to investigate the effect of baffle structure on the heat transfer and pressure drop in the shell side of a cross-flow tubular fixed bed reactor.

    The flow and temperature fields inside the shell were resolved using computational fluid dynamics (CFD), and a series of simulations were performed with a variable baffle number and baffle cut size, and the leakage between baffle and shell was also taken into consideration. The results were observed to be sensitive to the turbulence model. Six turbulence models were tried, and realizable k-ε model was proved as the best turbulence model by comparing the CFD results of heat transfer coefficient and pressure drop with empirical method results. The calculated outlet temperature, total pressure drop and average heat transfer coefficient of simulation and empirical methods were compared, and they were in a good agreement.

    The contours of velocity and temperature showed that there were obvious stagnation regions behind the baffles. The performance of heat transfer can be improved by increasing the number of baffle and decreasing the size of baffle cut, because these stagnation regions were eliminated, and the cross flow was better utilized. The simulation results also showed that the leakage between baffle and shell was beneficial to controlling the uniform distribution of temperature inside the shell. This leakage can reduce both pressure drop and heat transfer coefficient, but it can break the stagnation regions of the baffle back, which was useful to enhance the heat transfer and prevent local high temperature in those regions. However, the effect of clearance size between baffle and shell on heat transfer was needed to be studied in the future.