Practical Achievements on Biomass Steam Gasification in a Rotary Tubular Coiled-downdraft Reactor

Today, the impending stringent environmental norms and concerns about the depletion of fossil fuel reserves, have added impetus on development of cutting edge technologies for production of alternative fuels from renewable source, like biomass. Concept of biomass pyro-gasification offers platform for production a) of hydrogen b) hydrocarbons and c) value added chemicals etc. However, majority of these developments are either in nascent or in pilot/demonstration stage. In this context, there exists potential for hydrogen production from the raw gas of biomass steam gasification. In gaseous products of biomass steam gasification, there exist a lot of CO, CH4 and other hydrocarbons that can be converted to hydrogen through cracking, steam reforming and water gas shift reactions. In the present work, the characteristics of biomass steam gasification in an in-house designed rotary tubular coiled-downdraft reactor for high value gaseous fuel production from rice husk was studied through a series of experiments. The effects of reactor temperature, steam-to-biomass ratio and residence time on overall product gas yield and hydrogen yield were investigated. From the experimental results, it can be deduced that an optimum reactor temperature of 750oC, steam-to-biomass ratio (S/B) of 2.0 and a residence time (3.6 min.) contributed highest gas yield (1.252 Nm3/kg-ash and moisture free biomass). Based on the obtained experimental results, a projected hydrogen purity of above 65 volume% at a potential hydrogen yield of 18.36 wt% of the biomass organic content is foreseen. Despite the fact that, the yield of hydrogen varies from biomass to biomass which depends on inherent composition of the species, this process opens up pathway for production of the cleanest fuel as compared to other liquid products from biomass, which require further treatments for making in final form.