Two-step numerical procedure on the removal process of gaseous potassium chloride generated from waste incineration via the injection of sulfate-based additives
2020
Kim, Sangwoo | Kim, Beomjong | Lee, Uendo | Hwang, Jungho
Gaseous potassium chloride (KCl) that constitutes a relatively large portion of the combustion gas of municipal solid waste can condense on the surface of boiler heat exchanger tubes, causing severe corrosion attacks. To reduce the chlorine-induced high-temperature corrosion, sulfate-based additives have been used. In this study, a two-step numerical procedure is proposed to quickly predict the effect of the injection of sulfate-based additives on the removal of gaseous KCl. A computational fluid dynamics (CFD) simulation is first carried out to obtain the temperature distribution. Then, the thermal decomposition of sulfate additives, sulfation of gaseous KCl, and condensation of K2SO4 are calculated to predict the species concentration profiles at the temperature conditions given by the CFD simulation. After validation with a laboratory-scale experiment using NH42SO4, the procedure is applied to a pilot-scale boiler to examine the effects of NH42SO4, Fe2SO43, and Al2SO43. The calculation results show that each additive has an optimal injection temperature range: approximately 800 °C for NH42SO4 and 1000 °C for both Fe2SO43 and Al2SO43, which are consistent with the values reported in the literature. The expressions for the stoichiometric KCl removal efficiency of each additive are derived and compared with the calculated efficiencies.
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