The Implications of Burning a Blend of Waste Materials in a Fluidised Bed Combustor

A mixture involving wood, plastics, paper and textile materials was burned in a fluidised bed combustor to monitor the gaseous emissions and to analyse the ashes collected in different locations of the installation. The ashes collected were first analysed to verify the partitioning of heavy metals in different ash streams. They were then subjected to leaching tests to verify the solubility of different components present. There is a growing interest in utilizing wastes, which cannot be recycled for further use, for energy, particularly in Europe as the amounts are great and the cost of depositing them in landfills has become very considerable. These wastes are considered renewable sources and the recent policy is to encourage their use for energy, especially for decentralized energy production. However, these wastes may be contaminated and have to be verified that their utilization for energy does not bring about any adverse consequences on the environment. Each component making up the blend to be used as fuel needs to be analysed to determine not only its composition but also its heating value so that the final blend to be prepared could present minimum risk for emissions of pollutants, ideally less than coal and with a heating value comparable, at least, to that of coal. The results obtained suggest that i) the combustion efficiency was very high, ii) there was an enrichment of ashes with heavy metals in the cyclones compared to the bed material, iii) the gaseous pollutants were below the permitted limits and iv) the ashes did not have tendency for leaching. The mixture could, therefore, be used as a solid fuel in industry as a substitution for coal or heavy fuel oil.