Steam Gasification of Biomass-Derived Char for the Production of Carbon Monoxide-Rich Synthesis Gas

There is growing interest in the conversion of biomass and related materials into gaseous and liquid fuels. During fast pyrolysis of biomass in a fluidized-bed reactor, 15% of biomass is converted to char whereas 70% is converted to liquid and the rest to gas. In the present work, a systematic study has been conducted to explore the possibilities of using biomass-derived char for the production of various types of gaseous fuels and synthesis gas through pyrolysis and steam gasification in a tubular reactor. The pyrolysis experiments were carried out in the presence of nitrogen ( flow rate of 20 mL/min) in the temperature range of 700−800 °C. Steam gasification experiments were carried out in the temperature range of 650−800 °C, steam flow rate of 2.5−15 g/h/g of char. The reaction time was varied from 0.5 to 2.0 h. It has been found that a combination of lower steam flow rate (about 2.5 g/h/g of char), lower temperature (about 700 °C), along with lower reaction time (about 0.5 h) produces synthesis gas having a molar ratio of H 2 /CO favorable for Fischer-Tropsch synthesis. On the other hand, synthesis gas having very high H 2 /CO molar ratio (about 5−6) can be produced via the steam gasification reaction at a temperature of 800 °C, steam flow rate of about 10 g/h/g of char and a reaction time of 0.5 h. The heating value of the product gas at different process conditions has also been calculated.