Improvement of Pyrolysis Liquid Usability by Staged Condensation of Pyrolysis Vapours from Ablative Flash Pyrolysis of Barley Straw
The thermal conversion process "pyrolysis" converts biomass in the absence of air into two primary products: char and pyrolysis vapour. By cooling the vapours the condensable fraction can be separated as liquid phase from the permanent gases. The ablative flash pyrolysis, where heat transfer to the biomass particles happens in direct contact with a hot surface by mechanical force, aims at maximizing the liquid yield. The total condensates from straw directly disintegrate into two liquid phases: a lighter aqueous phase and a heavier, highly viscous organic phase. To increase the efficiency of processing and separation of individual substances, the pyrolysis vapours are condensed in a staged process, so groups of substances are enriched in the fractions respectively generated as opposed to total condensation. In this paper, the effect of pyrolysis temperature on the condensate yield and the formation of individual groups of substances were studied. The maximum of condensate yield was achieved at 540 degrees C. On the other hand more acids, alcohols and ketones have been formed with increasing the pyrolysis temperature from 486 to 580 degrees C. Furthermore, a staged condensation of pyrolysis vapours can be regarded as useful due to a significant enrichment of substance groups. Thus, an (economic) material use of the condensates is possible.