The characteristics of biomass gasification in multistage heating and gradient chain gasifier

•The effect of operating conditions on the results of BMF gasification was studied in the zone of drying, pyrolysis, oxidizing, and reducing, separately.•The characteristics of biomass gasification in multistage heating and gradient chain gasifier were observed.•The effect of gradient-chain on the disturbance of BMF was observed.•The operating conditions (e.g. residence time, gasification temperature, and gasifying agent) were optimized in different stages.

The characterization on gasification of biomass briquette in a sectional healing of reactor was studied in this article. The results indicated that the temperature of drying stage was higher than those of oxidizing and reducing stages in multistage heating and gradient chain gasifier (MHGCG). Through comparison with the normal situation, the gasification efficiency was improved significantly with the increase of the temperature of drying stage appropriately, and with the decrease of the oxidizing and reducing temperature. When the equivalence ratio (ER) was 0.28 in the oxidizing stage, the weight loss of biomass and the gasification efficiency was 43% and 56%, respectively. The volume fraction of O2, CO2, H2 and CO was 4%, 10%, 14% and 24%, respectively, and the ultimate volume fraction of NO, NOX, and SO2 was about 0.024%, 0.025% and 0.032%, respectively. In addition, most of the raw biomass (about 95%) was transferred to the discharge port of MHGCG. Therefore, the gradient-chain has little effect on the disturbance of biomass briquetting fuel (biomass briquette) in the vertical direction.