燃焼ガス中におけるダイオキシン類抑制の反応に関する熱力学的考察

概要

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The formation and decomposition of dioxins (PCDD/Fs) in combustion gas have been discussed by thermodynamic calculations for the C-O-H-Cl quaternary gas system. The effects of temperature and gas composition are briefly summarized by changing the conditions based on the following “reference gas”: O20.1 + CO 1.8 + H20.15 + HCl 0.9 + C2H3Cl 0.1 mol=O:2 + C:2 + H:1.5 + Cl: 1 mol The effects of various additions (inhibitors) on the decomposition of PCDD/Fs are evaluated by use of thermodynamic package HSC Chemistry. The changes of the reference gas composition are calculated at 300゜C by addition of inhibitors such as CaO, SO2, NH3, sodium salts, organic compounds, and metals. The amounts of PCDD/Fs decrease efficiently by the additions of these substances, but it is clarified that the decrements are always reproduced by change in basic quaternary C-O-H-Cl gas composition. Increase in O or H, and decrease in Cl result in decomposition of PCDD/Fs, and thus, the regulation of the quaternary gas composition is of primary importance to control PCDD/Fs. The derived amounts of PCDD/Fs by equilibrium calculation are much higher than those observed in practice because of kinetic reasons. Taking account of slow reaction rates of the formation of PCDD/Fs and solid carbon deposition, thermodynamic simulations for depression of the formation of PCDD/Fs are demonstrated.
社団法人資源・素材学会の論文
1999-10-25