Fast pyrolysis of stem wood was performed in a pilot-scale cyclone reactor with a reactor wall temperature of ∼750°C. Wood powder was introduced to the pyrolyzer at 20 kg/h during the experiments. Stable operation of the pyrolyzer was easily achieved, and the resulting yields of the products were 54.6 wt % of pyrolysis oil, 15.2 wt % of solid residue, and 20.1 wt % of gases. From the ingoing raw material, 3.4 wt % of the mass could be recovered as deposits, mainly on the walls of the reactor and in the oil condensing part of the plant. The mass and energy balance closures were approximately 93% and 89%, respectively. The physicochemical properties of the pyrolysis oil, solid residue, and noncondensable gas were measured and compared to values in the literature. The results also show that it is possible to produce an oil with a very low concentration of ash-forming elements because particle separation has already occurred in the cyclone reactor.

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Pyrolysis oil is a complex mixture of different chemical compounds with a wide range of molecular weights and boiling points. Due to its complexity, an efficient fractionation of the oil may be a more promising approach of producing liquid fuels and chemicals than treating the whole oil. In this work a sampling system based on fractional condensation was attached to a cyclone pyrolysis pilot plant to enable separation of the produced pyrolysis vapors into five oil fractions. The sampling system was composed of cyclonic condensers and coalescing filters arranged in series. The objective was to characterize the oil fractions produced from three different Nordic feedstocks and suggest possible applications. The oil fractions were thoroughly characterized using several analytical techniques including water content; elemental composition; heating value, and chemical compound group analysis using solvent fractionation, quantitative 13 C NMR and 1 H NMR and GC x GC-TOFMS. The results show that the oil fractions significantly differ from each other both in chemical and physical properties. The first fractions and the fraction composed of aerosols were highly viscous and contained larger energyrich compounds of mainly lignin-derived material. The middle fraction contained medium-size compounds with relatively high concentration of water, sugars, alcohols, hydrocarbonyls and acids and finally the last fraction contained smaller molecules such as water, aldehydes, ketones and acids. However, the properties of the respective fractions seem independent on the studied feedstock types, i.e. the respective fractions produced from different feedstock are rather similar. This promotes the possibility to vary the feedstock depending on availability while retaining the oil properties. Possible applications of the five fractions vary from oil for combustion and extraction of the pyrolytic lignin in the early fractions to extraction of sugars from the early and middle fractions, and extraction of acids and aldehydes in the later fractions.

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