350 MW超临界循环流化床机组SNCR脱硝喷枪投运策略优化试验
Optimization experiment of SNCR denitrification spray gun operation strategy for a 350 MW supercritical CFB unit
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摘要: 针对大型循环流化床（CFB）锅炉炉膛尺寸大、内部温度场与流场分布复杂的特点，选择性非催化还原（SNCR）脱硝技术在实际应用中常面临还原剂（如尿素或氨水）与烟气混合不均匀、脱硝效率偏低等问题。这主要是由于CFB锅炉炉内气固两相流动剧烈，且分离器入口区域烟气流速、温度及组分浓度存在显著空间差异，导致传统固定式喷枪难以实现全覆盖、均等化的还原剂喷射。为此，以某350 MW超临界CFB锅炉为试验对象，系统开展了SNCR喷枪投运策略优化研究。试验过程中，通过调整分离器入口处多支喷枪的组合投运方式，研究了不同投运策略对脱硝效率的影响规律。试验结果表明：低负荷工况下，温度是影响脱硝效率的主要因素，不同投运策略对脱硝效率的影响并不显著，运行上可以适当减少各分离器入口喷枪投运数量，降低喷枪磨损、改善脱硝效率；高负荷工况下，每个分离器入口投运喷枪数量存在最优区间，以4~6支为宜。投运策略上内侧喷枪数量应多于外侧，并采用内外侧间隔均匀布置的方式。通过优化喷枪投运策略，尿素耗量降低约27.8%，提高了机组脱硝效率。投运的喷枪数量增加可扩大还原剂的覆盖范围，而减少则有助于提高母管压力、增强还原剂的穿透深度，实际应用中需综合考虑两者的影响。本次试验获得与锅炉实际流场、温度场相匹配的还原剂喷射点位及组合策略，研究成果可为同类型CFB锅炉SNCR脱硝系统的运行优化提供工程参考。实际运行中NOx控制受多重因素综合影响，建议各电厂应结合自身机组的运行特点制定出适应性的喷枪投运策略。Abstract: For large-scale circulating fluidized bed (CFB) boilers characterized by large furnace dimensions and complex internal temperature and flow fields, selective non-catalytic reduction (SNCR) denitrification technology often faces practical challenges such as uneven mixing between the reducing agent (e.g., urea or ammonia water) and flue gas, resulting in low denitrification efficiency. This is mainly due to the intense gas-solid two-phase flow inside the CFB boiler furnace and the significant spatial differences in flue gas velocity, temperature, and component concentrations at the cyclone inlet region, which make it difficult for traditional fixed spray guns to achieve full coverage and uniform distribution of the reducing agent. To address this issue,
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