The behavior of flue gas from RDF combustion in a fluidized bed

Abstract

A combustion process of refuse derived fuel (RDF) in a fluidized bed has been recognized as a promising utilization technology for solid wastes management in Japan. To understand the combustion behavior of RDF was very important for the establishment of the RDF combustion technology. In this research, to explain a combustion behavior of RDF, several different types of RDF, which contained different chemical compounds, were incinerated in the fluidized bed combustor or fluidized bed boiler, and combustion tests were carried out under the steady state conditions. The experimental data of the CO, NO x , HCl and dioxin concentrations in the flue gas were measured by the continuous measurement system. It was found that CO concentration in the flue gas greatly increased with increasing the RDF feed rate and decreased with increasing the air ratio. The CO concentration was also significantly effected by the secondary air injection ratio and air distribution ratio. The NO x concentration and conversion of fuel-N to NO x of RDF contained metal compounds were far higher than that of the other RDFs. The conversion of fuel-N to NO x increased with increasing the calcium component ratio in RDF, because the calcium oxide promoted catalytically production of NO. On the other hand, the HCl concentration decreased with increasing the calcium component ratio. It was also found that the generating pattern of dioxins strongly depended upon the compositions of a RDF.