摘要
研究燃煤机组负荷变化对颗粒物排放特性的影响规律有利于实现煤炭的清洁经济利用。某电厂1000 MW超超临界燃煤机组运行负荷在600~900 MW时,采用低压撞击器(DLPI)对静电除尘器(ESP)前后和烟囱入口颗粒物进行采集测量。采用称重法获得颗粒物的质量浓度,采用X射线荧光探针(XRF)对其化学成分进行分析,揭示燃煤机组负荷变化对颗粒物排放特性的影响规律。结果表明,机组运行负荷变化对ESP前颗粒物的生成浓度没有影响,但负荷降低促进煤中Na、Ca和S向细颗粒物(PM_(10))迁移。负荷降低使矿物交互作用减弱是导致煤中矿物向PM_(10)迁移比例增加的主要原因,将增大电厂的除尘难度。机组高负荷运行(70%以上)时,负荷变化对ESP除尘效率影响不明显,但低负荷运行时会降低ESP除尘效率。机组湿法脱硫和湿电系统(WFGD+WESP)可进一步有效脱除烟气中颗粒物。机组运行负荷降低可延长烟气在WFGD和WESP中的停留时间,减少二次携带颗粒物的生成,进一步提高WFGD+WESP的除尘效率,保证机组在不同运行负荷条件下烟囱排放颗粒物质量浓度低于10 mg/Nm^(3)。
Revealing the influences of load change on particulate emission from coal-fired units are beneficial to the clean utilization of coal.Particular matter(PM)before and after electrostatic precipitator(ESP)and at the inlet of stack were sampled by low pressure impactor(DLPI)when the operating load of the 1000 MW ultra-supercritical coal-fired unit varied from 600 MW to 900 MW.The mass concentration of PM in the flue gas was achieved by weighting the mass of PM sample,chemical composition of PM was analyzed by X-ray fluorescence probe(XRF).The rules of PM emission under different operation loads of coal-fired unit were revealed.The results show that the decrease of unit load has insignificant effect on the PM concentration before ESP,but promotes the migration of Na,Ca and S in coal to fine particles(PM_(10)).That can be mainly due to the weaker mineral interaction under lower unit load conditions.It enhances the difficulty of dust removal from the flue gas.The load change has insignificant effect on the dust collection efficiency of ESP,when the unit is in high load(more than 70%).However,dust collection efficiency of ESP decreases when the unit is under low load.The wet desulfurization system and wet electrostatic precipitator(WFGD+WESP)of the unit can further remove the PM in the flue gas effectively.The decrease of unit load increases the duration of flue gas in the WFGD and WESP,and decreases the probability of PM further entrained by flue gas.Therefore,lower operation load of the unit improves the dust collection efficiency of WFGD+WESP.Operation of WFGD and WESP ensures that the concentration of PM from the stack is less than 10 mg/Nm^(3) under different operation load conditions.
作者
李洋
罗林
吴建群
吴昊
于敦喜
LI Yang;LUO Lin;WU Jianqun;WU Hao;YU Dunxi(Guangdong Yudean Jinghai Power Generation Co.,Ltd.,Jieyang 515223,China;State Key Laboratory of Coal Combustion,Huazhong University of Science&Technology,Wuhan 430074,China)
出处
《洁净煤技术》
CAS
北大核心
2021年第6期115-120,共6页
Clean Coal Technology
基金
国家重点研发计划资助项目(2016YFB0600600)
国家自然科学基金资助项目(52006080)。
关键词
煤燃烧
颗粒物
静电除尘器
除尘效率
coal combustion
particulate matter
ESP
dust collection efficiency
