Abstract |
The paper discusses a homogeneous, gas-phase reaction mechanism that has been developed to explain sulfur (S) and chlorine (C1) interactions in an industrial, fire-tube boiler, using No. 2 fuel oil (0.03% S) doped with copper naphthenate (CuNA) and 1,2-dichlorobenzene (1,2-diC1Bz). The experiments were intended primarily for the investigation of polychlorinated dibenzodioxin and furan (PCDD/F) formation. However, significant reduction of sulfur dioxide (SO2) from combustion of No. 2 fuel oil was also observed upon injection of 1,2-diC1Bz. Interaction between S and C1 has been of significant interest due to the potential of S to suppress the formation of PCDDs/Fs during cofired combustion of high-S coal with municipal waste (MW). A suggested mechanism is the gas-phase reaction SO2+C12+H20=S03+2HC1 that converts active molecular chlorine (C12)-formed in the post-flame zone by the metal-catalyzed Deacon process-to inactive hydrogen chloride (HC1). In this study, the gas-phase suppression reaction is represented by a series of elementary reaction steps compiled from previously validated reaction mechanisms. The model was able to explain the observed rapid conversion of S02 to S03 in the boiler experiments upon injection of 1,2-diC1Bz to a HC1 conversion of 60%. These results present a possible mechanism for gas-phase S and C1 interactions and a potential means of elucidating the S02 suppression mechanisms of PCDD/F formation during cofired combustion of high-S coal and MW. |