脱硫废水高温烟气蒸发过程中氯盐和铵盐的分解

Decomposition of Chloride and Ammoniate in the Evaporation Process of Desulfurization Wastewater With High Temperature Flue Gas

为实现脱硫废水零排放,脱硫废水高温烟气蒸发结晶技术逐渐发展起来,脱硫废水蒸发过程中结晶盐的高温分解可能是制约蒸发技术进一步推广应用的关键问题。介绍了火力发电厂脱硫废水的特点及蒸发结晶过程中盐分的稳定性,重点介绍了水合氯化镁的几种热分解机理。综合分析表明,在旁路高温烟气蒸发处理过程中,氯化镁和铵盐可热分解,分别产生氯化氢气体和氨气,将会引起后续脱硫废水排放量增加、烟囱出口氨浓度升高。最后讨论了旁路高温烟气蒸发系统引起电厂粉煤灰的质量降低等问题。

In order to realize zero discharge of desulfurization wastewater, evaporation and crystallization technology of desulfurization wastewater with high temperature flue gas has gradually developed. The decomposition of crystalline salts in desulfurization wastewater evaporation process is probably the key problem that may influence the further application of evaporation technology. This paper briefly introduced the characteristics of desulphurization wastewater in thermal power plants and the stability of salt during evaporation and crystallization. The thermal decomposition mechanism of hydrated magnesium chloride was introduced emphatically. The comprehensive analysis shows that magnesium chloride and ammoniate will be decomposed to produce hydrogen chloride gas and ammonia respectively, which will increase the content of chlorine ion in the desulphurization wastewater and ammonia concentration at chimney outlet. Finally,the quality reduction of fly ash in the evaporation process with by-pass high-temperature flue gas was also discussed.