FATE OF TRACE CONTAMINANTS FROM BIOMASS FUELS IN GASIFICATION SYSTEMS

摘要

There is growing interest in the use of biomass and other renewable CO{sub}2 neutral fuels in power generation systems. This interest is being stimulated by the search for electricity generation methods, which minimise environmental emissions and utilise readily renewable fuel sources, but have the attraction of allowing a diversification in power generation fuel sources. Unfortunately, compared to coals, these fuels contain different relative and absolute levels of trace contaminants (sometimes far in excess of coal) so existing plant designs/material specifications based on coal firing may need modification. An extensive list of compositions for potential fuels such as pine wood, wheat straw, a rang of grasses, sewage sludge and peat, has been compiled together with coal data for comparison. Most compositions reported in the literature are only partial analyses of the fuels, often targeted at their bulk combustion and/or gasification behaviour with far fewer reports of composition data that include analyses of all minor and trace metal species that are required for assessing the impact of the fuels and processes in material performance. From these data, the fate of typical levels of contaminants has been estimated through the hot gas paths of the various candidate power systems, using a software thermochermcal modelling package (MTDATA). Plant measurements of both trace elements and minor species in gasification processes have been gathered for comparison with these estimates.