Fast Pyrolysis of Wheat Straw—Improvements of Operational Stability in 10 Years of Bioliq Pilot Plant Operation

Abstract

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.