Design and operation of a mobile fast pyrolysis system utilizing a novel double pipe fluidized bed reactor

Abstract

A mobile fast pyrolysis system using a novel double pipe fluidized bed reactor with a capacity of 50 kg/h was designed and built. The structures of the main components, including the novel double pipe fluidized bed reactor, double bin pneumatic conveying feeder, jet/spray combined condenser, etc., are described in detail and experiments examining their performance are reported. Fast pyrolysis of larch sawdust was conducted at 400–550 °C to examine how temperature affects product yields and characteristics. The highest bio-oil yield was 68.6 wt% at 500 °C, and the yields of biochar and non-condensable gas were 19.2 wt% and 12.2% wt%, respectively. The chemical components of bio-oil included acids, aldehydes, ketones, phenols, furans, sugars, and other substances, and their proportions varied with temperature. Phenolic compounds were the most abundant components in the bio-oil with a peak content of 30.6% at 500 °C. The non-condensable gas was made mostly of CO2 and CO, which together peaked at 88.3 vol% at 400 °C. Furthermore, the energy performance of the pyrolysis process was analyzed. This research provides a reference for the industrial transformation of mobile fast pyrolysis technology.