Steam-oxygen blown circulating fluidised bed gasification for synthetic biofuel production: Pilot-scale reactor modelling, model-based reactor scale-up and analysis for power-biomass-to-liquid processes

Steam-oxygen blown gasification is a prominent gasification technology for producing synthetic biofuels and biochemicals from biomass. A 1.5D semi-empirical model is developed for circulating fluidised bed gasification. The model is validated using data from 500 kW pilot gasifier tests reported in the literature. The validated model is used in designing a 100 MW scale gasifier concept. The model is used to investigate the effect of the operating temperature and steam-to-biomass (S/B) ratio on the performance and producer gas composition of the large-scale gasifier. The validation study showed the model to predict producer gas composition accurately. The estimate was within +−15% for the main gas species. The parametric study illustrated producer gas composition to be more sensitive to the S/B ratio than operating temperature. The $H_2/\mathrm{CO}=2$ ratio can be achieved when an electrolyser is used to satisfy the oxygen consumption of the large-scale gasifier, and the obtained hydrogen side stream is mixed with syngas downstream of the gasifier. The large-scale simulation results are compared to literature data from different gasifiers. The comparison shows that the influence of the investigated parameters is small relative to the scattering of the data. The phenomena affecting the gas composition and performance of the gasifier are discussed. The findings of the study contribute to an understanding of the physical operation of the gasification process. The study presents the mass and energy balances of the large-scale scale gasifier, which can be used in conceptual studies of synthetic biofuel and chemical production.