EXPERIMENTAL AND NUMERICAL ANALYSIS OF SAWDUST-CHAR COMBUSTION REACTIVITY IN A DROP TUBE REACTOR

摘要

This article discusses the results of a combined experimental and numerical investigation of the combustion reactivity of sawdust char in a drop tube furnace. The work presented here was motivated by the lack of reliable data in the open literature on the combustion reactivity of woody biomass char. This study involved the experimental determination of the global kinetic param- eters of sawdust-char oxidation and the subsequent application of these parameters in a computational fluid dynamics (CFD) code. The modified code was employed for mathematical modeling of the sawdust-char combustion in the drop tube furnace. The experiments were conducted at furnace tempera- tures of 1473 and 1673 K in a 10mol% O_2 environment and 1473 K in air. Experimental results indicated that the bulk of the char oxidation reaction for sawdust occurred in Regime II where chemical reaction and pore diffusion rates are comparable. In addition, the sawdust char exhibited distinctive near- extinction combustion behavior at the early stage of the reaction. The com- bustion reactivity of the sawdust char, with an apparent reaction order (n) of 0.4, was comparable to that of some high-volatile bituminous coal chars. Good agreement was achieved between predicted and experimental results.