Oxygen-Blown Entrained Flow Gasification of Biomass - Results from a 100 kW Test Rig

Abstract

An entrained flow gasification test rig (100 kW, pneumatic fuel feeding 10–25 kg/h) was designed and constructed to be operated either with ambient air at 1000 - 1200 °C or with pure oxygen or an oxygen/steam mixture up to 1500 °C and up to 5 barg. In this work first results for the gasification of torrefied wood (mixture) and a raw wood (beech) with pure oxygen are presented. Process parameters are 70 kW thermal firing capacity with an air-to-fuel equivalence ratio λ of 0.4. Applied measurement methods are: online gas analysis, particle sampling (for calculating Carbon Conversion) and SPA (tar analysis) It turned out that one of the most important points for high conversion and cold gas efficiency is a stable flame. To reach this, the fuel stream from the pneumatic feeding system has to be very continuous. This can be achieved by increasing N2-input in the conveying pipe. For raw beech wood powder the additional N2-input has to be higher than for the torrefied wood powder also to avoid plugging. Under the investigated conditions raw beech wood shows better carbon conversion and higher cold gas efficiency. On the other hand the tar concentration is lower and the heating value of the product gas higher for torrefied wood.