Experimental evidence indicates that sulfur in coalsuppresses dioxin formation from chlorine compounds during coalcombustion. Therefore, cofiring coal with high chlorine, municipalrefuse derived fuels (RDF) or paper industry wastes should beeffective in suppressing dioxin formation from these fuels. Sincesulfur dioxide (S02) emissions must also be controlled it isdesirable to combine dioxin and S02 control in the combustionprocess. Tests in a commercial scale stagging coal combustor haveshown substantial dioxin reduction when firing coal, and whencofiring coal and RDF. Separately, high S02 reductions weremeasured with sorbent injection in this same combustor. Theobjective of this planned Phase I experimental project is todetermine the feasibility of combining the dioxin and S02 controlin one step with sorbent injection into the stagging combustor. Achlorine compound will be used as a surrogate for the chlorinewaste fuels. It will be mixed with coal and injected with thesulfur sorbent into the combustor. A set of combustion tests willbe performed in which the concentration of chlorine and sorbent,injected with the coal, will be varied. For each condition, thedioxin concentration will be measured in the stack of the boilerto which the combustor is attached, using EPA approved methods. The Phase I test objective will be to achieve the same dioxinreduction in the high chlorine cases as with coal only, and atthe same time achieve high S02 reductions. If the Phase I testsare successful, the Phase II effort will focus on fullycharacterizing the simultaneous dioxin and S02 control in thecombustor using both surrogates and chlorine content wastestreams.Anticipated Results/Potential Commercial Applications as described by the awardee:The air cooled stagging combustor, whose installedcost on existing boilers is projected at less than $10/lb of steam,can efficiently cofire coal and solid waste fuel combustion withinternal environmental control. The municipal refuse incinerationand paper manufacturing industries are the primary markets for thiscombustor technology application. Successful elimination of dioxinemissions will allow both industries to continue using currentchlorine based processes and avoid costly changes to otherprocesses. It will enable them to dispose of chlorine containingsludges by cofiring them with coal in the combustor. During PhaseI and Phase II of this project efforts will be implemented tomarket this combustor technology to these industries.
