Effect of feedstock moisture content on the quality of liquids from fast pyrolysis of spruce wood

The presence of water in biomass influences its behaviour during pyrolysis and affects the physical properties and quality of the pyrolysis liquid. The effects of varying feed moisture content were investigated in a 150g/h rig. The feedstock was spruce; the range of temperatures covered 450-550°C and the range of feed moisture contents from bone dry to 13.4 % wet basis. The average vapour residence time varied between 0.48 and 0.56 seconds. The results obtained show that for higher feed moisture contents the maximum liquid yield on a dry feed basis occurs at lower reactor temperatures. For higher pyrolysis temperatures and at higher feed moisture contents investigated it was found that the pyrolysis oil was unstable and phase separated. Bone dry feed material on the other hand led to the production of very viscous oil, particularly at higher reaction temperatures. Finally, the highest liquid yields, around 76%, were found for feed moisture contents between 7-11 % and reactor temperatures around 475°C, conditions that also gave the most stable oil and lowest viscosity. Results and discussion The results of the pyrolysis experiments with different moisture content spruce and at reactor temperatures from 450?C to 550?C are summarised below, all data are presented on a dry feed basis: 1. As the reactor temperature increased from 450?C to 550?C, the yield of char decreased and th