Fluidized Bed Combustion of Coal, Renewable Fuels, and Waste: Current Status and Developments

Abstract

Coal is a very important fuel because of its high calorific value of up to about 33 MJ/kg and its worldwide distribution (refer also to Lackner et al. 2013). Coal is available on the international market and can be obtained from many mines of the world. However, coal is a fossil fuel, rich in carbon and produces CO2, a major greenhouse gas. Beside its carbon content, nitrogen and sulfur may be present in the coal as well at significant levels. The nitrogen in the fuel may be converted via complex reaction routes to NO x which contributes to acid rain formation and shows direct negative effects to human health. The sulfur in the coal is oxidized to SO2 which subsequently contributes to acid rain formation and direct adverse effects of the human health. Beside high-quality coals which are low in ash, also coals with high amounts of ash and moisture exist. These coals are significantly lower in their energy contents and usually used locally because of their availability and lower costs.