SCR超低排放综合诊断及闭环优化
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摘要
针对燃煤电厂烟气脱硝系统存在的流场不均、氨逃逸导致空气预热器堵塞以及NO_x排放不能在全负荷段稳定达标等典型问题,提出了SCR超低排放综合诊断及闭环优化策略。结合某630 MW机组实施超低排放改造具体案例,以在线大数据和性能检测为基础,数值模拟和系统诊断为手段,通过模拟评估及试验分析进行预判,提出改进方案并予以优化、修正和实施,最后结合性能试验对超低排放改造实施效果进行验证。研究结果表明,采用多元手段进行SCR系统综合诊断和闭环优化, NO_x浓度场标准偏差从18.6%下降至4.89%,脱硝效率从86.7%提高至89%以上,NO_x排放质量浓度稳定低于50 mg/m~3,SCR系统出口氨逃逸质量浓度从16 mg/m~3下降至0.75 mg/m~3,超低排放改造效果显著。
In view of the typical problems in the flue gas denitration system, such as poor flow uniformity, ammonia escape, air preheater clogging, failure of NO_x stable ultra-low emission in full load section, a comprehensive diagnosis and closed-loop optimization strategy for ultra-low emission of SCR is proposed. Combining with the 630 MW implementation case, with the online large data and performance testing as the base, numerical simulation and system diagnosis as the means, by means of simulation evaluation and test analysis, the improvement scheme is put forward, optimized, revised and implemented, and finally combined with the performance test to verify the effect. The comprehensive diagnosis and closed-loop optimization of the SCR system are performed with multiple means. Comparing before and after modification, the standard deviation of NO_x concentration field decreases from 18.6% to 4.89%, the denitration efficiency increases from 86.7% to over 89%, and the chimney NO_x emission concentration is steadily below 50 mg/m~3, the ammonia escaping mass concentration at the outlet of the SCR system decreases from 16 mg/m~3 to0.75 mg/m~3. The effect of ultra-low emission reconstruction is remarkable.
In view of the typical problems in the flue gas denitration system, such as poor flow uniformity, ammonia escape, air preheater clogging, failure of NO_x stable ultra-low emission in full load section, a comprehensive diagnosis and closed-loop optimization strategy for ultra-low emission of SCR is proposed. Combining with the 630 MW implementation case, with the online large data and performance testing as the base, numerical simulation and system diagnosis as the means, by means of simulation evaluation and test analysis, the improvement scheme is put forward, optimized, revised and implemented, and finally combined with the performance test to verify the effect. The comprehensive diagnosis and closed-loop optimization of the SCR system are performed with multiple means. Comparing before and after modification, the standard deviation of NO_x concentration field decreases from 18.6% to 4.89%, the denitration efficiency increases from 86.7% to over 89%, and the chimney NO_x emission concentration is steadily below 50 mg/m~3, the ammonia escaping mass concentration at the outlet of the SCR system decreases from 16 mg/m~3 to0.75 mg/m~3. The effect of ultra-low emission reconstruction is remarkable.
引文
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[18]ZHAO Dazhou,LIN Da,ZHANG Zhongping.Flow field simulation and optimization design of SCR of 660 MW power unit based on CFD study[C]//IOP Conference Series:Earth and Environmental Science.Hangzhou,2018.
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[20]DU Jun,ZHANG Yan,CAI Zeliang.Simulation and experimental study of SCR injection system[J].Polish Maritime Research,2018,25(S2):49-55.
[2]薛建明,柏源,管一明,等.燃煤电厂超低排放综合技术路线[J].电力科技与环保,2016,32(3):12-15.XUE Jianming,BAI Yuan,GUAN Yiming,et al.Study on the ultralow emission comprehensive technology of coal-fired power plants[J].Electric Power Technology and Environmental Protection,2016,32(3):12-15.
[3]刘英进,李杰义,李兵,等.330MW燃煤机组SCR流场优化及提效改造[J].节能与环保,2017(6):67-71.LIU Yingjin,LI Jieyi,LI Bing,et al.Optimization and improvement of SCR flow field of 330MW coal-fired unit[J].Energy Conservation and Environmental Protection,2017(6):67-71.
[4]王汉青,易检长,李端茹,等.SCR脱硝系统导流板优化设置的数值模拟[J].湖南工业大学学报,2015,29(2):1-7.WANG Hanqing,YI Jianchang,LI Duanru,et al.Numerical simulation of guide plate optimization setting of selective catalytic reduction denitrification system[J].Journal of Hunan University of Technology,2015,29(2):1-7.
[5]王为术,上官闪闪,路统,等.600MW燃煤锅炉SCR系统烟道导流板设计[J].郑州大学学报(工学版),2015,36(4):37-40.WANG Weishu,SHANG GUAN Shanshan,LU Tong,et al.Design of splitters in flue of SCR system for a 600 MW coal-fired boiler[J].Journal of Zhengzhou University(Engineering Science),2015,36(4):37-40.
[6]陈拓,李德波,成志红,等.600 MW火电机组SCR脱硝系统“超低排放”改造性能试验[J].热能动力工程,2017,32(12):126-130.CHEN Tuo,LI Debo,CHENG Zhihong,et al.Experimental research on performance test after SCR denitrification system“near-zero emission”reconstruction[J].Journal of Engineering for Thermal Energy and Power,2017,32(12):126-130.
[7]PARK S-Y,RUTLAND C.Analysis of SCR performance differences caused from flow characteristics of wall flow and flow through type substrate:A simulation study[J].Chemical Engineering Science,2013,88:69-78.
[8]YE Xinglian.Research and application of multi-dimension numerical simulation optimization for SCR DeNOx flow field[C]//IOPConference Series:Earth and Environmental Science.Hangzhou,2018.
[9]GAN Xubo,YAO Dongwei,WU Feng,et al.Modeling and simulation of urea-water-solution droplet evaporation and thermolysis processes for SCR systems[J].Chinese Journal of Chemical Engineering,2016,24(8):1065-1073.
[10]秦天牧,刘吉臻,杨婷婷,等.火电厂SCR烟气脱硝系统建模与运行优化仿真[J].中国电机工程学报,2016,36(10):2699-2703.QIN Tianmu,LIU Jizhen,YANG Tingting,et al.SCR denitration system modeling and operation optimization simulation for thermal power plant[J].Proceedings of the CSEE,2016,36(10):2699-2703.
[11]GAO Yanhong,LU Qingcai,BIAN Lingtao.Numerical simulation and optimization of flow field in the SCR denitrification system on a600 MW capacity units[J].Energy Procedia,2012,14:370-375.
[12]方朝君,卢承政,白晓龙.SCR脱硝系统超低排放运行优化技术研究[J].中国电力,2018,51(2):143-148.FANG Zhaojun,LU Chengzheng,BAI Xiaolong.Study on operation optimization of SCR denitrification with ammonia-injection for ultralow emission[J].Electric Power,2018,51(2):143-148.
[13]赵宗让.电厂锅炉SCR烟气脱硝系统设计优化[J].中国电力,2005,38(11):69-74.ZHAO Zongrang.Design optimization of SCR system for coal-fired boilers[J].Electric Power,2005,38(11):69-74.
[14]LIU Guofu,BAO Wenyun,ZHANG Wei,et al.An intelligent control of NH3 injection for optimizing the NOx/NH3 ratio in SCRsystem[J/OL].Journal of the Energy Institute.2018.(2018-10-23)[2018-10-30].https://doi.org/10.1016/j.joei.2018.10.008.
[15]ADAMS B,SENIOR C.Improving design of SCR systems with CFDmodeling[C]//Proceedings of the 2006 Environmental Controls Conference.Pittsburgh,2006:32-33.
[16]毛奕升,吴智鹏,张孝天.火电厂SCR脱硝系统喷氨优化调整及烟气取样方法改进[J].中国电力,2017,50(4):167-171.MAO Yisheng,WU Zhipeng,ZHANG Xiaotian.Optimization and adjustment of ammonia injection system and improvement of flue gas sampling method for SCR denitrification system of thermal power plants[J].Electric Power,2017,50(4):167-171.
[17]CHU K W,YU A B.Numerical simulation of complex particle-fluid flows[J].Powder Technology,2008,179(3):104-114.
[18]ZHAO Dazhou,LIN Da,ZHANG Zhongping.Flow field simulation and optimization design of SCR of 660 MW power unit based on CFD study[C]//IOP Conference Series:Earth and Environmental Science.Hangzhou,2018.
[19]PONZINI R,FEO D,PIERI R.SCR-DeNOx power plant design optimization using HPC platforms:A possible automatic workflow[J].Journal of the Serbian Society for Computational Mechanics,2017,11(2):40-49.
[20]DU Jun,ZHANG Yan,CAI Zeliang.Simulation and experimental study of SCR injection system[J].Polish Maritime Research,2018,25(S2):49-55.