A Experiment Study Of Preparing Bio-oil By Fast Pyrolysis From The Rice Husk In The Fluidized Bed

Biomass energy is of great interest as a renewable and environment-friendly energy source because there would be no net carbon dioxide discharging during its utilization. There are a large number of biomass resources in China, which can be transformed into bio-oil with higher density through fast pyrolysis. The using of bio-oil can improve the utilization efficiency of biomass energy, and has great significance in alleviating energy shortage and environmental pollution.Firstly, the paper concludes the utilization status and conversion technology of biomass energy at home and abroad, and then describes the reaction principle, the typical biomass fast pyrolysis devices and the study of bio-oil condensation in detail.In addition, the existing problems of biomass fast pyrolysis currently and the purpose of this paper are also discussed.According to the characteristics of dilute phase transport in fluidized bed,biomass pyrolysis and bio-oil condensate, a fast pyrolysis reactor with the screw feeding device and bio-oil condenser improved was designed to pyrolysis the rice husk for bio-oil, which was condensed by two-stage condensation, the first using spray and plate column combination method, and the second using tubular heat exchanger. Experiments were conducted to study the factors affecting the yield of bio-oil such as reaction temperature, fluidizing gas flow and feed rate. The result was shown that the whole reaction device could run normally for a long time, while the bio-oil could condense rapidly, the yield of bio-oil was increasing and then decreasing with the reaction temperature, fluidizing gas flow and feed rate increasing.Physical and chemical properties of biomass oil cooled by two stage condenser were analyzed. The result was shown that the density, pH, calorific value, and kinematic viscosity of bio-oil achieved by the first condenser were higher than the bio-oil achieved by the seconder condenser. Moreover, the bio-oil achieved by the first condenser had more components, in which the acids, ketones, esters and phenols were the more compositions relatively. In addition, the kinematic viscosity of bio-oilachieved by the first condenser decreased with the temperature and its thermal stability is poorer, which was completely decomposed at 150℃.The energy consumption and output of the system were analyzed based on Aspen Plus. The result was shown that the energy consumption from preheating and cooling of nitrogen accounted for the main part of the whole energy consumption,which restricted the development of fast pyrolysis. In addition, the by-product coke and non-condensable gas could burn to heat biomass and nitrogen realizing auto-thermal reforming.