Behavior of chlorine during the combustion of single RDF pellet

In order to explain the de-hydrochloric (de-HCl) phenomena in densified refuse-derived fuel (RDF) combusted in a fluidized bed, experiments under combustion and pyrolysis conditions for some laboratorial model RDFs and RDF made from municipal solid waste are carried out in an electric furnace. The combustion characteristics of each single RDF pellet under similar combustion conditions as those in fluidized bed combustion (FBC) or stoker combustion are studied. The emission of HC1 through the flue gas, and the capture of chlorine by Ca additive in the RDF during the combustion are measured. It is found that the fraction of Cl captured by the residual ash increases from 0 to nearly 70% under similar combustion conditions as in FBC when the molar ratio of Ca/(S+0.5 Cl) is increased from 0 to 12.6. It is also found that the fraction of Cl captured by the residual ash apparently decreases with increasing oxygen concentration under ambient cenditions. The devolatilization process of RDF is verified to take a very important part of de-HCl process. Moreover, the effect of temperature profile in the RDF pellet, which is varied with the heating rate of RDF and the ambient oxygen concentration, on the de-HCl is discussed. Accordingly FBC has been verified to be beneficial for de-HCl reaction.