超超临界二次再热机组锅炉全负荷脱硝特性

Denitration performance of an ultra-supercritical unit boiler with double-reheat cycle under full load conditions

以华能安源发电有限责任公司超超临界660 MW二次再热机组锅炉和华能莱芜电厂超超临界1 000 MW二次再热机组锅炉为研究对象,通过锅炉校核热力计算对二次再热机组锅炉不同负荷工况下烟气脱硝系统选择性催化还原(SCR)装置入口烟温特性进行了研究,并与电厂实际运行数据和常规超超临界一次再热机组锅炉进行了对比。结果表明:本文计算结果与电厂实际运行结果吻合很好;超超临界二次再热机组锅炉能够实现锅炉全负荷脱硝,随着锅炉负荷的降低,其SCR装置入口烟温逐渐降低,在最低30%BMCR负荷时,二次再热机组锅炉SCR装置入口烟温仍高于320℃,比相同容量的常规一次再热机组锅炉SCR装置入口烟温高30~40℃;超超临界二次再热机组锅炉能实现全负荷脱硝的主要原因在于锅炉给水温度显著提高,比常规一次再热机组锅炉给水温度提高约30℃。该研究结果对超超临界二次再热机组的设计和建设提供了参考和借鉴。

Taking the ultra-supercritical 660 MW unit boiler with double-reheat cycle in Huaneng Anyuan Power Plant and the ultra-supercritical 1 000 MW unit boiler with double-reheat cycle in Huaneng Laiwu Power Plant as the research objects, thermal checking calculation was conducted to investigate the temperature characteristics of flue gas at the SCR denitration device inlet at different unit loads. Moreover, the calculation results were compared with the power plants＇ practical operation data and that of the conventional ultra-supercritical unit boilers with single reheat cycle. The results show that, the calculation results agreed well with the power plants＇ practical operation data. The ultra-supercritical unit boiler with double-reheat cycle can realize flue gas denitration at full load condition. With the loss of the boiler load, the flue gas temperature at the SCR denitration device inlet reduced gradually, it was still higher than 320 ℃ when the boiler load was as low as 30%BMCR, which was 30-40 ℃ higher than that of the conventional unit boiler with single reheat cycle and of the same capacity grade. The main cause of realizing full load denitration for the ultra-supercritical unit boiler with double-reheat cycle lies in the dramatic increasing of the feed water temperature, which is about 30 ℃ higher than that of the conventional unit boiler with single reheat cycle. The research results provide reference to the design and construction for the ultra- supercritical unit with double-reheat cycle.