Production of bio-oil from rice straw and bamboo sawdust under various reaction conditions in a fast pyrolysis plant equipped with a fluidized bed and a char separation system

Rice straw and bamboo sawdust were pyrolyzed in a bubbling fluidized bed equipped with a char separation system. The effects of the reaction conditions on the production of bio-oil, and the efficiency of a char removal system, were investigated. In each experiment, the mass balance was established and the products’ chemical and physical characteristics were examined. To elucidate how the reaction temperature affects the production of bio-oil, experiments were conducted at a temperature range of 415–540 °C in the case of the rice straw and 350–510 °C in the case of the bamboo sawdust. In addition, the influence of the feed size, the feed rate, and the kind of fluidizing medium on the production of bio-oil with each feed was investigated. The optimal reaction temperature for the production of bio-oil was between 440 and 500 °C in the case of the rice straw and 405–450 °C in the case of the bamboo sawdust. With respect to the bamboo sawdust, the maximum bio-oil yield was above 70 wt.% of the product. In the study of the influence of the feed rate and the feed size on the production of bio-oil, a higher feed rate and a smaller feed size were found to be more effective in the production of bio-oil. Finally, the use of product gas as a fluidizing medium enhanced the production of bio-oil. The main compounds of bio-oil were phenolics, furfural, acetic acid, levoglucosan, guaiacol, and alkyl guaiacol. In addition, high-quality bio-oils, which contained low concentrations of alkali and alkaline earth metals, were produced due to the excellent performance of the char separation system.