Dual fluidized bed biomass gasification: Temperature variation using pure CO2 as gasification agent

In many industrial processes, the climate-damaging gas CO2 is produced as undesired by-product. The dual fluidized bed biomass gasification technology offers the opportunity to solve this problem by using the produced CO2 within the process as gasification agent. Therefore, a 100 kW pilot plant at TU Wien was used to investigate the use of CO2 as gasification agent by converting softwood as fuel and olivine as bed material into a product gas. A temperature variation from 740 to 840°C was conducted to investigate the change of the main product gas components over the gasification temperature. With increasing temperature, CO and H2 increased and CO2 decreased. Additionally, another parameter variation was conducted, where the typically used gasification agent steam was substituted stepwise by CO2. Thereby, the amount of CO and CO2 increased and the content of H2 decreased. These trends resulted in a declining H2/CO ratio and a decreasing lower heating value when CO2 was increased as gasification agent.