HIGH TEMPERATURE AIR GASIFICATION PROCESS OF WOOD BIOMASS IN AN ENTRAINED DOWN-FLOW GASIFIER

摘要

High temperature air gasification of wood biomass in an entrained down-flow gasifier was carried out. The objective of this study is to evaluate the air gasification performance and to understand the optimum air gasification conditions. Gasification operation was conducted at high temperature (over 1300 K) to prevent tar generation. Pulverized wood was used as the gasification fuel, which was injected directly to the entrained down-flow gasifier to keep the high temperature. In the experiment, pulverized wood was sieved under 60 mesh and supplied at the rate of 19 to 27 kg / h. The oxygen-carbon molar ratio (O/C) was employed as the operational condition. The maximum temperature was kept over 1300K under the condition of O/C from 1.26 to 1.84. Target product gas was hydrogen and carbon monoxide in this process. Hydrogen was 9 %, and carbon monoxide was 19 % at the O/C of 1.45, even when the produced gas was diluted by nitrogen. Carbon to gas conversion was almost 100 %, and the tar generation was under the detection limit. Cold gas efficiency reached 67 %. Considering the scale-up effect based on the experimental result, cold gas efficiency could be achieved 75 % when the wood feeding rate was around 1000 kg/h, and the air ratio was 0.32 (O/C=1.32).