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Conference paper2005

Environmental aspects of biofuel combustion

Seisenbaeva, Gulaim

Abstract

Application of Biofuels has been recognized as an attractive source of energy for heat and power production. The main advantages of bioenergy application lay in zero carbon dioxide effect, renewable nature of biofuel resources, their good accessibility and affordable price. The burning of biofuels is, however, as any combustion technology not a completely problem-free process. The composition of biofuels, even the high quality wood fuels, is relatively complex. They contain mainly cellulose – a “pure” carbohydrate polymer, but also such components as vegetable proteins – possible source of nitrogen and sulphur, resins (mainly terpenoids) – volatile and difficult to oxidize substances and also metal salts. The composition of fuel is strongly dependent upon its source. Thus, coniferous wood is richer on terpenoids, deciduous wood, especially the bark, is containing more of vegetable proteins, while secondary wood sources are contaminated with metal salts and conservation media, such as chlorophenols. The incomplete combustion, even that of the highest quality wood fuel such as dry pellets (almost pure cellulose), is inevitably associated with formation of benzene and phenol. The latter compounds are subsequently converted to benzofuranes and dioxins due to the catalytic action of the flying ash (products of carbonization of cellulose contaminated with iron oxide from the walls of the boilers). The mechanisms and conditions of benzofuranes and dioxins formation will be discussed in detail. The commonly applied technical and chemical solutions aimed at reduction of emissions of these undesired exhausts from both, on one hand, large and, on the other hand, small and medium scale combustion will be presented. There will also be given examples of new materials perspective for decreasing the process temperatures and simultaneous improvement of the completeness of combustion and decreasing the NOx emissions

Keywords

biofuel; combustion; environmental aspects

Published in


Publisher: Institutionen för Bioenergi

Conference

Bioenergy 2005 Sustainable Biomass Management Chains to meet Kyoto Requirements