Maria P. Aznar

Biomass gasification in atmospheric and bubbling fluidized bed: effect of the type of gasifying agent on the product distribution

The effect of the type of gasifying agent used in biomass gasification on product distribution (gas, char and tar yields) and gas quality (contents in H2, CO, CO2, CH4,…, tars) is analyzed. Gasifying agents taken into account are: air, pure steam, and steam–O2 mixtures. Process considered is biomass gasification in atmospheric and bubbling fluidized bed. Previous results got by Herguido et al. (Ind. Eng. Chem. Res. 1992; 31(2): 1274–82), Gil et al. (Energy and Fuels 1997; 11(6): 1109–18) and Narvaez et al. (Ind. Eng. Chem. Res. 1996; 35(7): 2110–20) are compared. Such authors carried their research on biomass gasification under similar conditions but varying the gasifying agent. Three different gasifying agent-to-biomass ratios are needed and used to compare results. The relationships between the H2, CO,…, tar contents in the flue gas and the type and amount of gasifying agent used are shown after a carefully analysis.

The Deactivation of Tar Cracking Stones (Dolomites, Calcites, Magnesites) and of Commercial Methane Steam Reforming Catalysts in the Upgrading of the Exit Gas from Steam Fluidized Bed Gasifiers of Biomass and Organic Wastes.

Summary The steam gasification of cellulosic wastes and biomass in fluidized beds is improved by placing a catalytic bed after the gasifier. The goal is to eliminate the tar in the exit gas and to diminish or to increase the 4–8 vol % of CH 4 in the gasifier exit gas. For such purposes three very different kinds of catalysts are being used: 1st) calcined stones like dolomites, calcites and magnesites, 2nd) Commercial CH 4 (and tar) steam reforming catalysts (basically Harsaw Ni-3288) and 3rd) Commercial methanation catalysts (mainly Topsoe R-67). The experimental conditions in which they are very active have been found. They all deactivate by coke and their life is, till now, of only some hours.