First three pictures showing bright blue carbon monoxide flame, like a gas stove flame, and then a very faint blue hydrogen flame, not seen in daylight. Hardwood chips are the fuel in these three.
Gasification of pelletised fuel cane bagasse a waste residue from an energy crop known as fuel cane was investigated to evaluate the potential of fuelling solid oxide fuel cells (SOFCs) with the raw fuel gas produced. Tars produced during gasification of the bagasse in a 50 kWe air-blown downdraft autothermal gasifier were collected, quantified and characterised and the tar dew point evaluated. The concentration of tar collected was 376 ± 27 mg m−3 of dry syngas (at 273 K, 101 kPa), emphasising the efficiency of the tar cracking reactions in the oxidation zone of the gasifier. However, although tar production was low, the typical mixture of tar compounds produced exhibited a high tar dew point of 90 ± 5 °C and was dominated by Class 2 and 5 tars which condense readily even at low concentrations. Additionally Class 1 tars had a mass fraction of 8% of the total tar produced. Therefore the calculated tar dew point underestimates the actual tar dew point and a high potential for fouling of SOFC anodes exists. Consequently primary or secondary gas cleaning treatment measures targeting the production or occurrence of Class 1, 2 and 5 tars will be essential for long term operation of SOFC power generating systems fuelled by raw fuel gas from fuel cane bagasse.
The technology associated with indirect biomass liquefaction is currently arousing increased attention, as it could ensure a supply of transportation fuels and reduce the use of petroleum. The characteristics of biomass-oxygen gasification in a bench-scale laminar entrained-flow gasifier were studied in the paper. Experiments were carried out to investigate the influence of some key factors, including reaction temperature, residence time and oxygen/biomass ratio, on the gasification. The results indicated that higher temperature favored H2 and CO production. Cold gas efficiency was improved by N10% when the temperature was increased from 1000 to 1400 degrees C. The carbon conversion increased and the syngas quality was improved with increasing residence time. A shorter residence resulted in incomplete gasification. An optimal residence time of 1.6 s was identified in this study. The introduction of oxygen to the gasifier strengthened the gasification and improved the carbon conversion, but lowered the lower heating value and the H2/CO ratio of the syngas. The optimal oxygen/biomass ratio in this study was 0.4. The results of this study will help to improve our understanding of syngas production by biomass high-temperature gasification.
