Production Of Synthesis Gas By High Temperature Steam Gasiifcation Of Sawdust/Sawdust-derived Char

There are a few defects existing in biomass-derived synthesis gas, mainly low content ofH₂in fuel gas, high tar content, complicated compositions and so on. High temperature steamgasification can improve the quality of biomass-derived synthesis gas. In this study, hightemperature steam gasification of biomass was studied at atmospheric pressure in a fixed bedreactor. Sawdust and sawdust-derived char were used as feedstock.Main contents and results are summarized as follows:1, Synthesis gas was produced by high temperature steam gasification of sawdust. Hightemperature steam gasification of sawdust was studied at atmospheric pressure in a fixed bedreactor. Experiments were carried out at750°C，800°C,850°C,900°C,950and1000°Cwith different steam flow rates in the range of0.32to1.02g/min and a reaction time of10min.The effects of temperature and steam flow rate on carbon conversion, synthesis gas yield, heatvalue and its compositions were mainly studied. It has been found that steam gasification ofsawdust was highly reactive, particularly at high temperature; synthesis gas yield was in therange of0.81-1.74L/g. The results show that steam flow rate and temperature have strongeffects on the carbon conversion, synthesis gas yield, heat value and its compositions. Theconversion of this char was maximum （99.47%） at950°C with steam flow rates of0.67g/min.The product gas obtained was mainly a mixture of H₂, CO, CO₂, and CH₄. Under the presentreaction conditions, synthesis gas （H₂+CO） produced by steam gasification of char was in therange of63⁷5mol%, The low heating value of the product gas was in the range of10.5¹1.5MJ/Nm³, and the H₂/CO molar ratio was about1.06².26.2, Synthesis gas was produced by high temperature steam gasification of sawdust-derivedchar. Steam gasification of sawdust-derived char was studied at atmospheric pressure in a fixedbed reactor. Experiments were carried out at800°C,850°C,900°C,950°C and1000°C withdifferent steam flow rates in the range of0.25to0.85g/min and a reaction time of15min. Theeffects of temperature and steam flow rate on conversion of char, synthesis gas yield, heat value and its compositions were mainly studied. It has been found that sawdust-derived charwas highly reactive, particularly at high temperature, synthesis gas yield was in the range of0.4-2.97L/g. The results show that steam flow rate and temperature have strong effects on theconversion of char, synthesis gas yield, heat value and its compositions. The conversion of thischar was maximum （78.7%） at1000°C with steam flow rates of0.85g/min. Under the presentreaction conditions, synthesis gas （H₂+CO） produced by steam gasification of char was in therange of68⁸0mol%, The low heating value of the product gas was in the range of8.9⁹.6MJ/Nm³, and the H₂/CO molar ratio was about3.12⁶.32.3, Synthesis gas was produced by pressurized steam gasification of sawdust. Pressurizedsteam gasification of sawdust was studied in a fixed bed reactor. Experiments were carried outat800°C,850°C and900°C with steam flow rate1.00g/min and a reaction time of30min.The effects of reaction pressure on carbon conversion, synthesis gas yield, heat value and itscompositions were mainly studied. It has been found that the characteristics of pressurizedsteam gasification of biomass are different from that at the atmospheric pressure. Pressurizedsteam gasification of sawdust was more reactive. Hydrogen content is also higher in the gasproduction of biomass gasification, and it reaches more than60%. Compared with theatmospheric pressure, the carbon conversion and synthesis gas yield increase, and wasmaximum94.7%and2.03L/g, respectively. The results show that reaction pressure has strongeffects on synthesis gas compositions and heat value. As total pressure increases from0to0.4MPa, carbon dioxide and methane yields increase, whereas carbon monoxide yield decreases.The low heating value of the product gas increases to some extent, and the H₂/CO molar ratiowas about5.1⁶.7.To sum up, steam is a favorable agent for synthesis gas production from biomassgasification. The results suggest that there is a strong potential for producing synthesis gasfrom steam gasification of sawdust, further used for Fischer–Tropsch synthesis or methanoland DME synthesis.