MODELING OF SECONDARY REACTIONS OF TAR (SRT) USING A FUNCTIONAL GROUP MODEL

During flash pyrolysis/gasification of biomass, tar is the major product, which reaches up to 70%. This tar causes a lot of problems that present significant impediments to the application of biomass gasification systems. The reduction or decomposition of tar at the gasification process becomes one of the most necessary and urgent problems. As a result, a great need exists for a comprehensive model that helps to understand the mechanism of tar decomposition/cracking (second reactions of tar), which will possibly improve biomass gasifiers and furnaces design. The purpose of this study was at detail modelling of the second reactions of tar (SRT) using a functional group model. Types of gasses, yields and kinetic rates during the SRT within temperature range of 500-1200 o C are modelled and validated with experimental measurement from literature. The model discusses the scenario of tar cracking mechanism, the quantitatively most important product from the SRT, and the best indicator for the tar conversion process. The model also helps to classify tar compounds into different categories with identifying quantitatively the most important compound from each category as well as the proper method to crack each one. The model can explain the complicated behavior of parallel, series and overlapping reactions of different tar compounds at the SRT conditions.

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