超超临界锅炉宽负荷脱硝改造方案对比分析

Comparison and Analysis on Wide-load Denitration Retrofit Schemes for an Ultra-supercritical Boiler

为实现某超超临界锅炉宽负荷脱硝,综合分析对比省煤器分级、省煤器流量置换、烟气旁路等技术改造方案。计算结果表明:该机组采用烟气旁路的技术改造方案具有较好的可行性,通过在水平低温再热器进口抽取高温烟气,能够提升选择性催化还原(SCR)脱硝系统进口烟气温度,使其不低于300℃,满足机组30%锅炉最大连续蒸发量(BMCR)工况脱硝投运要求,实现宽负荷脱硝。

For the wide-load denitration in an ultra-supercritical boiler,a comprehensive comparison and analysis was conducted on following technical retrofit schemes,such as the economizer grading,the flow displacement of economizer,the bypass of flue gas,etc.Calculation results show that the technical retrofit scheme with the bypass of flue gas in the unit has a good feasibility.By extracting the high temperature flue gas at the inlet of the horizontal low temperature reheater,the flue gas temperature at the inlet of the selective catalytic reduction(SCR)denitration system could be improved,and which could be maintained above 300℃.This may satisfy the requirements of the denitration operation of the unit under 30%boiler maximum continuous rating(BMCR)load,and realize the wide-load denitration.