Eulerian-Lagrangian simulation of air-steam biomass gasification in a bubbling fluidized bed gasifier

Abstract

To numerically study biomass gasification in a three-dimensional bubbling fluidized bed, a CFD-DEM (computational fluid dynamics – discrete element method) model with heat transfer and homogeneous and heterogeneous chemical reactions is implemented. An ideal reactor model is used for the air-steam bubbling fluidized bed (BFB) gasification reactor assuming perfectly mixed solids and plug flow. A validated computational particle fluid dynamics (CPFD) model has been applied to investigate the sensitivity analysis of mesh grids as well as to find the optimum number of grids. The result shows that 7452 grid cells are the optimal number of cells for the existence BFB gasifier. The effects of key process operating parameters such as steam to biomass ratio (SB), as well as temperature shows that by enhancing the SB ratio or reactor temperature, gas yields increase. H2 and CO2 concentrations promote by increasing the steam to biomass ratio while CO and CH4 production drop. The optimal value of SB for the gasification process can be found in the range of 0.3 to 1.

Electrically Heated Fluidized Beds─A Review

“…A few studies have considered internal Joule heating. For example, in a study by Samani, internal Joule heating was employed in a bubbling fluidized bed for a calcination step in a calcium looping process . Many studies have investigated the heat transfer between a fluidized bed and submerged tubes filled with flowing fluid.…”

“…By electrifying the calciner, the need to capture CO 2 from fossil fuel combustion to heat the calciner is eliminated. Samani explored calcination in an electrically heated bubbling fluidized bed applied to calcium looping and showed that this was a feasible approach . In addition, Samani carried out a comparison study for cement calcination and showed that, when an EHFB was used instead of traditional calciners, there was no negative impact on the process and the quality of the product.…”