Overview of Biomass Combustion

Abstract

The main combustion systems for biomass fuels are presented and the respective requirements are discussed. Wood stoves and stick wood boilers are used for individual house heating. Under stoker furnaces are used for wood chips from native wood with low ash content. Combustors for pulverized wood are used for dry wood residues (saw dust etc.) in industrial boilers or for co-combustion in power plants. For fuels with high ash content an efficient ash removal system is needed and mainly moving grate firings are used. Fluidized bed combustion is an option if a wide variety of fuels (including biomass fuels) is burnt. However, fluidised bed combustors are only used for large scale combustion. For biofuels with low ash fusion temperature like grass, straw, miscanthus etc., slagging on the grate and at the combustion chamber walls can cause severe operation problems usually above 850 °C - 1000 °C, depending on the fuel. For straw and similar biofuels, furnaces for whole bales like cigar burners can be used. The main functions of a biomass combustion system and the respective requirements are discussed in the paper.