Computational modeling and investigation of fluidized bed gasification process

Energy production from carbon-based solid materials by gasification has become an essential research subject. Gas production from solid materials is a very complex phenomenon where physical and chemical events come together. Besides, since the gasification process involves many parameters, it is challenging to measure each parameter with an experimental study. Therefore, an advanced modeling approach is needed to maximize the produced synthetic gas's efficiency, design a new gasifier, and optimize process parameters. Firstly, the hydrodynamics of gasification has been studied. Next, a two-dimensional (2-D) gasification system was simulated using the commercial code ANSYS-FLUENT. The chemical kinetics of the devolatilization and char combustion chemical reactions of the process was modeled using the UDF. In another step, a simple, accurate, and comprehensive three-dimensional (3-D) CFD model has been developed to solve, research, and optimize this complex problem. In the following stages, the development of the LES turbulence model, DDPM models, and a new solution model to the gasification problem is presented. After the mesh independence study and model validation, the system's efficiency was calculated. The standard k-ɛ model among the RANS-based turbulence models was chosen as the most appropriate approach. Gasifier design parameters have been optimized using the RSM. The WALE model has been accepted as the most suitable model among those LES models examined. DDPM model's results are also quite consistent. When the gasifier makes an angle of 45o with the horizontal, the product gas components are increased. Solid particle porosity decreases the efficiency.