Fast pyrolysis of lignocellulosics in a twin screw mixer reactor

• A complete and detailed description of the 10 kg/h fast pyrolysis process development unit for the first time
• Combined recovery of pyrolysis char and condensate demonstrated
• New data for a fast pyrolysis system consisting of a twin screw reactor with steel balls as recirculated heat carrier
• Joint condensation of pyrolysis char and oil

A process development unit (PDU) with 10 kg/h biomass capacity was designed, built and operated for fast pyrolysis of biomass. A twin-screw type reactor, in earlier applications used for treatment of coal, oil shale, oil sand and oil refinery residues, was used. Test campaigns with a variety of biomass types were performed. The results with hard-wood, softwood, wheat straw and wheat bran are reported and discussed in this paper, verifying the suitability of the twin screw reactor along with a new product recovery procedure. Liquid pyrolysis condensate, termed bio-oil, is the main product of FP and the yields are about 65 ± 10 wt.% for wood but only about 50 ± 10 wt.% for cereal straw, which is a typical result for all fast growing types of biomass with higher ash content. These product yields and properties are similar to those found for other FP reactor types and recovery procedures.