Biomass chemical looping gasification for syngas production using LD Slag as oxygen carrier in a 1.5 kWth unit

Abstract

Biomass Chemical Looping Gasification (BCLG) is an autothermic gasification process that provides pure syngas for many applications, including liquid biofuels production. Finding low-cost materials that can be used in the process is a key issue, especially when they come from waste. In this sense, LD Slag is a by-product of the steel industry used as an oxygen carrier in Chemical Looping Combustion with good results. This work investigates the use of LD Slag as oxygen carrier in a continuous 1.5 kWth BCLG unit. The effect of the main operational variables (temperature, oxygen-to-fuel and steam-to-biomass ratios) and the use of CO2 instead of steam as gasification agent were analysed. LD slag allowed the process with high biomass conversions, Xb > 90%, carbon conversion efficiencies, ηcc > 90%, and syngas yields, Y ≈ 0.66 Nm3/kg of dry biomass, at conditions corresponding to autothermal operation. A lifetime of 300 h under reducing conditions was inferred and agglomeration problems were never detected. LD slag can be considered a suitable material for BCLG since it is possible to obtain high-quality syngas at autothermal conditions from different types of biomass with low tar generation and CO2 emissions.