Design and operation of a down-tube reactor demonstration plant for biomass fast pyrolysis

•A novel down tube reactor demonstration plant for biomass pyrolysis was developed.•The maximum bio-oil yield was obtained at 500 °C up to 52.5 wt.%.•CO2 and CO in non-condensable gases accounted for 90.4 vol.% at 400 °C.

A novel down-tube reactor demonstration plant has been designed and built with the biomass throughput capacity of over 300 kg·h− 1. The main components of the pyrolysis demonstration plant were described and their performance was tested and evaluated. Preliminary experiments were conducted at the selected range of 400-550 °C to investigate the effect of temperature on the products. The components of non-condensable gases and the chemical compositions of bio-oil were studied. The good features of the reactor (high heat transfer rate, short residence time, good liquidity of biomass and ceramic balls, etc.) were beneficial to increase the yield of bio-oil. The maximum bio-oil yield was obtained at 500 °C up to 52.5 wt.%, with the yield of gas and char being 27% and 20.5%, respectively. The major components of non-condensable gas were CO2 and CO which were accounted for 90.4 vol.% at 400 °C. The chemical compositions of bio-oil are also affected by temperature above all the proportion of ketones, acids, furans, phenols and sugars. Acids is the main product and the maximum yield is up to 32.3 wt.% at 550 °C. This study has provided a referenced basis for the industrial biomass pyrolytic liquefaction demonstration plant.