The Effect Of Biomass Feedstock Type & Process Parameters On Achieving The Total Carbon Conversion In The Large Scale Fluidized Bed Gasification Of Biomass
One option for the production of liquid biofuel in Finland is based on fluidized bed gasification of biomass and Fischer-Tropsch synthesis process. The totalcarbon conversion achieved in the gasifier, operating at temperatures below 1000°C, depends mainly on the reactivity of solid char residue. The reactivity of the char residue is affected by temperature, partial pressures of the reactants H2O and CO2 and product gas components (H2 and CO), which are inhibiting the reactivity. In this reactivity, catalytic active substances, alkaline and earth-alkaline metal compounds, occurring naturally in biomass play a significant role. We studied the effects of the above-mentioned factors on various barks, like spruce, pine, birch, aspen, which are the most potential biomass feedstock to be used in the large-scale gasification in Finland. The measurements were carried out in the pressurized thermobalance in the conditions relevant for the pressurized oxygen gasification (pressure up to 20 bar). Reactivity of biomass char increased with temperature, which is obvious, but the increase of pressure did not necessarily mean increase in reactivity. Reactivity of different biomasses, and also different parts of biomass varied, such as thin pine bark had more than 5 times higher reactivity than thick pine bark, and lower than spruce bark. In general, ash sintering ranged from none to weak, in some cases the sintering was stronger at high pressure than at low pressure at the same temperature. Reactivity in the gas mixture including all the gas components was lower than in 100% steam, increase in temperature increased the reactivity significantly but in higher temperatures, ash sintering was detected. The parameters measured will be used for the development of the gasifier model.
- Authors / Editors:
- Moilanen Antero