Bio-oil production from fast pyrolysis of rice husk in a commercial-scale plant with a downdraft circulating fluidized bed reactor

Bio-oil, a promising candidate to replace fossil fuels, has received considerable attention for its sustainability, resource diversity and environmental benefits. Industrial production of bio-oil is urgently needed. In this study, a downdraft circulating fluidized bed reactor commercial-scale fast pyrolysis plant with biomass throughput of 1-3 t h− 1 is studied. Rice husk was processed at a fast pyrolysis temperature of 550 °C to evaluate the plant operation status. The system was continuously operated for 80.42 h. The thermal properties of the feedstock (rice husk), dust (separated from feedstock), char and heat carrier were analyzed and the bio-oil properties such as water content, pyrolytic water content, viscosity, density, pH, heating value, solid content and ash content were analyzed and presented. All the tested properties of the bio-oil meets the pyrolysis liquid biofuels standards in ASTM D7544-12 for Grade G biofuels, except for the water content of the bio-oil, which is slightly higher than that of Grade G biofuels. In energy balance analysis, the potential recovered energy of the three main products was 8.0 ± 1.1, 2.1 ± 0.1 and 5.3 ± 0.7 MJ kg− 1 for bio-oil, char and non-condensable gas, respectively, which shows that the largest portion of the energy in biomass was recovered in the bio-oil.