Design and Simulation of a New Micro Fluidized Bed Reactor By Computational Fluid Dynamics
Fluidization
2019
Fluidization XVI
General Paper Pool
6C: Modeling and Simulation
Wednesday, May 29, 2019 - 11:50am to 12:02pm
Such reactors are usually endothermic and should operate at a high temperature with a desired gas residence time. Micro fluidized bed reactors are promising reactors to save time and cost of experimental investigations when especially designed to mimic an operation at commercial scale and to screen operating conditions, feedstock formulations, and bed material physicochemical properties in terms of feed conversion, product selectivity and gas-solid interactions, e.g. agglomeration and attrition.
Authors have designed and developed a micro fluidized bed reactor where both gas and solid phases operate in batch mode, and an induction heating mechanism supplies the required heat with a high heating rate to stay at the setpoint temperature, i.e. up to 1200 oC. A centrifugal impeller takes in the outlet gas from the bed and returns it to the bed though internal tubes immersed into the reactor, i.e. gas sparger. The tubes are also heating elements; that is, the generated heat on the external surface of the tubes by the induction heating is transferred to the bed.
Computational fluid dynamics was employed to optimize dimensions of the reactor and the gas circulation system so that the impeller rotates at a speed below 5000 rpm enabling fluidization of Geldartâs group B particles with negligible wall effect.
The sliding mesh technique was used for numerical simulation of the impeller rotation. Prediction of the turbulence in the system was done by using the K-omega turbulent model and the hydrodynamics of the fluidized bed reactor was simulated by the Eulerian multiphase approach. The SIMPLE algorithm was used for pressure-velocity coupling and the second order upwind was utilized to obtain precise results. The results show that the gas flow rate is proportional to the impeller diameter, however, the shape of the blades does not have a considerable effect. Based on the numerical results, the design of the impeller and the reactor was optimized.