Bio-oil from rice straw by pyrolysis using fluidized bed and char removal system

Rice straw was pyrolyzed in a bench scale plant equipped mainly with a fluidized bed, a char separating system and a quench system. The influence of reaction temperature on the production of bio-oil, the efficiency of a char-separating system and some physical, and chemical analyses of bio-oil, product gas and char were studied. Bio-oils obtained in experiments showed very low content of alkali metals, and solid content in bio-oil was ∼ 0.03 wt %. As reaction temperature increased, the amount of gas increased. There was an optimum temperature to produce more bio-oil. At 412° and 516°C, the yield of oil was relative constant to give a maximum yield of 50 wt % and then decreased distinctly with increasing temperature. The yield of biomass was lower than in the case of wood pyrolysis. Methane, CO, and CO₂ consisted mainly of product gas. Ethylene and ethane were other important components in the product gas. Reduction of density and increase of pH value in comparison with typical bio-oil from wood was caused mainly by high content of water in bio-oil.