Fast pyrolysis is the first step of the bioliq concept, which is developed at the Karlsruhe Institute of Technology (KIT) together with Air Liquide (Lurgi Technologies) for synthetic fuel production from lignocellulosic biomass via gasification. In the 2 MW bioliq fast pyrolysis pilot plant, shredded wheat straw is mixed with a hot heat carrier (sand) in a twin screw mixer reactor. At a temperature of 500 °C and in the absence of oxygen, the biomass particles are rapidly decomposed within seconds and pyrolysis gas, solids, and organic and aqueous condensates are produced. Representative results of the product yields and properties obtained from selected pyrolysis test campaigns from 2013 to 2015 are presented. It is shown that the mass ratio between the two liquid condensates can be adjusted by appropriate process design and operating conditions. Product stability is discussed, giving evidence that, by process internal recycling of the organic condensate, a controlled thermal maturing can be performed. It could be demonstrated in the pilot scale that stable pyrolysis products can be produced from ash-rich biomass feedstocks, such as wheat straw.

The bioliq process developed at the Karlsruhe Institute of Technology (KIT) aims at the conversion of lignocellulosic biomass into synthetic biofuels and chemicals. The process follows a two-stage concept combining decentralized pretreatment of biomass via fast pyrolysis and centralized large-scale gasification and synthesis. The process was specifically designed to convert ash-rich biomass residues, such as wheat straw, requiring special design features at least in the upstream processes. The 2 MW fast pyrolysis pilot plant at KIT was operated with wheat straw from 2009 to 2018 and since then with miscanthus. A substantial increase from less than 5 tons of wheat straw converted per test run in 2012 to more than 50 tons in 2018 was achieved. In total, up to 2018, more than 260 tons of wheat straw were converted to pyrolysis products within a total of 500 h of steady operation. Representative results of the product yields and properties were presented for test campaigns from 2015 to 2018 and compared to a process demonstration unit of the same design but with a downscale factor of 50 (10 kg/h). Mass yields from both plants are in good agreement and consistent with literature data. Experience from longer-term operation and major technical modifications made to improve the operational stability of the plant are described.

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