Abstract:Pyrolysis is an important way of biomass resources utilization. As a liquid product of biomass pyrolysis, biooil has good application prospects in future energy market. However, the problems of low calorific value, high viscosity, high moisture content, high corrosiveness, and poor stability problem exist until now, which constrain further application of biooil. At present, many scholars at home and abroad focus on staged utilization of biooil, by different separation methods to yield the biooils with diverse physical and chemical properties, and then by further purification to obtain the high quality of biooil. Fractional condensation can realize realtime primary separation of biooil, which can facilitate further refinement, so the field has become research focus. In order to achieve the fractional condensation of biooil,,various condensation modes were studied in worldwide. Spray condensation were widely used to achieve the aim of rapid condensation because it can quickly reduce the temperature of pyrolysis gas. The tube condensation mainly depending on indirect heat transfer was used in largescale chemical production and its technology was mature, so tube condensation was applied to the research of fractional condensation. Based on the previous researches on fractional condensation unit, a fractional condensation unit using constant temperature condensation was designed, of which condensation levels and heat exchange area can be adjusted flexibly. By the independent design of multilevel condensing unit and adopting camellia seed shells as pyrolysis materials, fractional condensation tests on the pyrolysis volatiles of camellia seed shells at 500℃ were carried out, and three fractional biooil products under the condensation temperature levels of more than 165℃ and 165~120℃, below 120℃ were received. The physical and chemical characteristics of the products were analyzed, and the analysis results of the first two levelfractional products at more than 165℃, 165~120℃ showed that moisture content effectively reduced and gross calorific value was more than 23MJ/kg on average, 44% more than the calorific value obtained by conventional condensation, but kinematic viscosity was not improved. With condensation temperature dropped, kinematic viscosity had significant reduction in each group of biooil and pH value was slightly rose. Combining the thermal analysis curves with comprehensive combustion characteristic index to analyze combustion characteristics of biooil, the results showed that biooils of primary separation obtained by fractional condensation had obvious differences, and YY2 demonstrated the best combustion performance. In conclusion, realtime primary separation of pyrolysis volatiles generally was achieved by dependently designed fractional condensation and the characteristics of each stage’s product were varied. The device designed can provide a reference for design of fractional condensation of pyrolysis volatiles and lay a theoretical foundation for the further application of fractional biooil.