Experimental and numerical studies on integrated gasification and combustion of biomass

Mathematical modelling and numerical simulation of second-order reaction kinetics for fast and slow exothermic reactions has been applied with the aim to estimate the development of composition and temperature profiles downstream of the flame reaction zone. The effects of slow and fast exothermic reactions on the formation of the flame composition and temperature profiles are specified and analysed with account of the combustion of CO and H₂. The effect of the reaction rates on the formation of the flame reaction zone is estimated by comparing the results of numerical simulation with the results of experimental study to assess the main factors controlling the combustion characteristics at gasification and combustion of biomass. An experimental study of the two-stage process of biomass thermo-chemical conversion was conducted using a pilot device with an integrated biomass gasifier and a water-cooled combustor. The primary stage of biomass thermal decomposition provides the formation of an axial flow of product gas entering the combustion section from the gasification section. The secondary swirling air provides mixing of the axial flow of combustible gas with the swirling air flow and initiates the formation of a reaction zone downstream the combustor. The complex local measurements of temperature and composition at different stages of biomass thermo-chemical conversion confirm a faster burnout of hydrogen downstream of the flame reaction zone, determining the dominant combustion of combustibles at the primary stage of the swirling flame formation.