Effects of the Preheated Temperature and the Change in Gas Composition on Soot Formation in the Gas Reforming Process by Partial Combustion Method

Abstract

Partial combustion can be an effective way to reform fuel gases. The possible application we assume is reforming of tar in a producer gas from woody biomass gasification. The reforming process of tar by partial combustion of the producer gas is conducted in a gas reformer by the combination of oxidative cracking and thermal cracking of tar. The partial combustion type gas reformer is an apparatus stage subsequent to the biomass gasifier. The inverse diffusion flame is formed when the oxidizer for partial combustion is supplied to the producer gas. Cracking and polymerization of the tar occur simultaneously at proximity of the inverse diffusion flame. This polymerization of tar into soot is, however, a significant problem in the gas reformer, e.g. the reduction of the carbon conversion ratio and the change in temperature field by radiation from soot. The experimental and numerical study have been performed to clarify effects of hydrogen addition to the oxidizer on soot formation and growth of the polycyclic aromatic hydrocarbons (PAHs) that is precursor of soot. The main results from experiments are as follows. The increase in the preheated temperature of model producer gas suppresses soot formation. This is because the increase in preheated temperature leads the fraction of toluene to be low. TSI (Threshold Sooting Index) of toluene (model tar) is relatively high within components in the model producer gas.