High-temperature steam gasification of pine particles for hydrogen-rich gas

Abstract: The objective of the research was to use pine particles as raw material with self-made downdraft gasifier system platform for gasification test. The test was carried out under different conditions of steam flow rate and gasification temperature. Analysis of biomass gasification reaction mechanism was done by using equilibrium theory and chemical reaction kinetics of chemical reaction. Our results showed that method of granulation of biomass wastes can effectively improve stacking density of biomass. By using this method, pine wastes stacking density can be as high as 520 kg/m3. Also, by using pine particles for gasification, the bridging phenomenon of material accumulation in the furnace was decreased, thus making the test in a continuous and stable condition, and improving the biomass gasification effect. With the increase of gasification temperature, the degree of gasification reactions was increased as well as the steam reforming which helped the participation of hydrocarbon and coke As such hydrogen content increased, and the volume fraction of H2 increased from 23.38% at 700℃ to 44.79% at 950℃ which nearly doubled that in 700℃ Moreover, the volume fraction of CnHm decreased with the gasification temperature increase. However, due to the conversion of carbon monoxide and steam after 900℃, the volume fractions for H2, CO, and CO2 decreased with the increase of temperature. Besides, high-temperature steam had higher specific enthalpy, which might promote the reforming reaction of steam towards the generation of H2 The high temperature steam is also a gasification agent and heat carrier in the gasification process. It provides partial energy of biomass gasification reactions. Steam flow is another important indicator of high temperature steam gasification technology. In the range of temperature of 850-950 ℃, the increase of steam flow increased the steam reforming which was in the participation of hydrocarbon and coke. With steam flow increased from 0.3 to 0.9 kg/h, the volume fraction of H2 increased from 37.06% to 47.67%, the change of the volume fraction of CO was stable. The volume fraction of CO2 increased, but the volume fraction of CnHm decreased. Because of the sequentially increase of steam flow, the residence time of steam in the furnace reduced, and that made reaction not sufficient. Therefore, the gas yield and hydrogen production rate increased with the increase of the steam flow. The gas yield and hydrogen yield increased with the increase of the steam flow rate, and then decreased. Especially, with regard to gas quality, when the steam flow rate was 0.6 kg/h with a gasification temperature of 900 ℃, gas yield and hydrogen yield were 2.69 m3/kg and 101.8 g/kg respectively. At this time, the ratio of the steam flow rate and biomass in the reaction was about 0.95, the ratio of the steam quantity and the reaction of the reaction was about 0.95, and it was the best condition for the tests. This study provides the necessary basis for the promotion of the technology in the commercial industry. It is capable of providing partial energy of biomass gasification reactions.