The complex research on the technical conditions of energy application of wood pyrolysis bio-oil

The slow pyrolysis is a viable technology for the production of different solid products. However, its effective implementation requires utilization of material flows occurring in gaseous and liquid phases. Because liquid products of slow pyrolysis, typically referred to as bio-oil, are just by-product, their combustion characteristics are poorly studied. Current article presents the comprehensive experimental studies of the technical conditions of the slow pyrolysis bio-oil retrieved at commercial pyrolysis facility. The studies cover the composition and physicochemical properties of bio-oil, spraying characteristics, droplet ignition and combustion, and analysis of gas-phase combustion products. The bio-oil sample had relatively high density ( ρ = 1180 kg/m 3 ) and dynamic viscosity (184.16 mPa s). The pour ( T pp = 7 °C) and flashpoint ( T fp = 133 °C) were also high. The lower heating value was 25.01 MJ/kg. The majority of properties was consistent with requirements of ASTM 7544, while viscosity, pour point, and ash content were not. The study on bio-oil spraying was carried out using hydrodynamic setup equipped with pneumatic mechanical nozzle and cross-correlation camera. The fuel jet had a homogeneous structure with an average droplet diameter exceeding 0.2 mm. Ignition and combustion were studied using combustion chamber with varying the heating medium temperature in the range of 400–800 °C with a 50 °C step. The ignition delay and total combustion times of the bio-oil sample were exponentially decreasing with increasing heating medium temperature. In the temperature range of 400–500 °C, the thermal transformation proceeded in the oxidation mode, while at temperatures above 500 °C, the flame with periodic formation of microexplosions was observed.