Characterization of tars from a novel, pilot scale, biomass gasifier working under low equivalence ratio regime

Abstract

Gasification is a process that converts solid fuel to gas, which could allow the broader implementation of biomass for small and commercial scale electricity generation. However, such units would, in many cases, have to work within one system with intermittent energy sources, thus having to cope with new requirements regarding flexibility. Tars are unwanted by-products of gasification, and their presence introduces additional operation and maintenance problems. The requirement for the low load operation could potentially exacerbate these problems. The aim of this work is the characterization of the tars from a novel, pilot scale, biomass gasifier, developed by the Energy Research Center of the Technical University of Ostrava, during the low load operation. The amount of GC detectable compounds, excluding benzene, reached approximately 6.2 g/m(3) when working at the equivalence ratio of 0.06. Additionally, tar deposits from the gas cooler were analysed, showing that not all compounds classified as tars have a similar impact on the deposition. Recently developed concept of a tar deposition diagram was implemented, to account for a different propensity towards the formation of such deposits. The concept seems to be advantageous, in comparison to grouping the tars according to existing classification, based on the chemical structure.