燃煤机组选择性催化还原脱硝特性试验
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摘要
针对某1 000MW超超临界机组的选择性催化还原反应系统,采用数值计算与试验结合的方法研究了该机组选择性催化还原脱硝的性能。建立了燃煤机组燃烧后脱硝系统液氨蒸发器蒸汽质量流量模型;研究了脱硝效率对NH_3质量流量和蒸汽质量流量的影响,入口NO质量浓度对脱硝效率的影响,以及NH_3与NO_x物质的量比、氧气体积分数和反应温度对脱硝效率和SO_2/SO_3转化率的影响。结果表明:脱硝的温度范围为360～370℃,最佳反应温度为367℃;当脱硝效率为80%时,NH_3质量流量和蒸汽质量流量分别为446kg/h和275kg/h;脱硝效率随入口NO质量浓度的升高而提高;当NH_3与NO_x物质的量比为1时,脱硝效率为95.3%,为保证脱硝效率及氨逃逸率,NH_3与NO_x物质的量比应控制在1～1.2;随着氧气体积分数的提高,脱硝效率降低,而SO_2/SO_3转化率增大。
Numerical simulations and experimental tests were conducted on the selective catalytic reduction(SCR)system of a 1 000 MW ultra-supercritical unit to study its de-NO_x performance,including a steam consumption model of liquid ammonia evaporator established for the de-NO_x system,with focus on the effects of denitration efficiency on the NH_3 mass flow and steam flow,inlet concentration of NO on the denitration efficiency,as well as NH_3/NO_x molar ratio,oxygen concentration and reaction temperature on the denitration efficiency and SO_2/SO_3 conversion rate.Results show that the temperature window is 360-370℃,and the optimal reaction temperature is 367℃.When the denitration efficiency is 80%,the NH_3 mass flow and the steam mass flow would be 446kg/h and 275kg/h,respectively.The denitration efficiency increases with the rise of inlet concentration of NO.When NH_3/NO_x molar ratio is 1,the denitration efficiency would be 95.3%,and to ensure the denitration efficiency and ammonia escape rate,the NH_3/NO_x molar ratio should be controlled within 1-1.2.The denitration efficiency reduces and the SO_2/SO_3 conversion rate increases with rising oxygen concentration.
Numerical simulations and experimental tests were conducted on the selective catalytic reduction(SCR)system of a 1 000 MW ultra-supercritical unit to study its de-NO_x performance,including a steam consumption model of liquid ammonia evaporator established for the de-NO_x system,with focus on the effects of denitration efficiency on the NH_3 mass flow and steam flow,inlet concentration of NO on the denitration efficiency,as well as NH_3/NO_x molar ratio,oxygen concentration and reaction temperature on the denitration efficiency and SO_2/SO_3 conversion rate.Results show that the temperature window is 360-370℃,and the optimal reaction temperature is 367℃.When the denitration efficiency is 80%,the NH_3 mass flow and the steam mass flow would be 446kg/h and 275kg/h,respectively.The denitration efficiency increases with the rise of inlet concentration of NO.When NH_3/NO_x molar ratio is 1,the denitration efficiency would be 95.3%,and to ensure the denitration efficiency and ammonia escape rate,the NH_3/NO_x molar ratio should be controlled within 1-1.2.The denitration efficiency reduces and the SO_2/SO_3 conversion rate increases with rising oxygen concentration.
引文
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[16] MALPARTIDA I,MARIE O,BAZIN P,et al.The NO/NOxratio effect on the NH3-SCR efficiency of a commercial automotive Fe-zeolite catalyst studied by operando IR-MS[J].Applied Catalysis B:Environmental,2012,113-114:52-60.
[2]孙虹,华伟,黄治军,等.基于CFD建模的1 000MW电站锅炉SCR脱硝系统喷氨策略优化[J].动力工程学报,2016,36(10):810-815.SUN Hong,HUA Wei, HUANG Zhijun,et al.CFD-based numerical simulations on optimization of the ammonia spraying strategy in a 1 000 MW SCR denitrification system[J].Journal of Chinese Society of Power Engineering,2016,36(10):810-815.
[3]姜烨,高翔,吴卫红,等.选择性催化还原脱硝催化剂失活研究综述[J].中国电机工程学报,2013,33(14):18-31.JIANG Ye,GAO Xiang,WU Weihong,et al.Review of the deactivation of selective catalytic reduction deNOxcatalysts[J].Proceedings of the CSEE,2013,33(14):18-31.
[4]高岩,栾涛,彭吉伟,等.燃煤电厂真实烟气条件下SCR催化剂脱硝性能[J].化工学报,2013,64(7):2611-2618.GAO Yan,LUAN Tao,PENG Jiwei,et al.DeNOx performance of SCR catalyst for exhaust gas from coal-fired power plant[J].CIESC Journal,2013,64(7):2611-2618.
[5] BONINGARI T,KOIRALA R,SMIRNIOTIS P G.Low-temperature catalytic reduction of NO by NH3over vanadia-based nanoparticles prepared by flameassisted spray pyrolysis:influence of various supports[J].Applied Catalysis B:Environmental,2013,140-141:289-298.
[6] MAITARAD P,ZHANG Dengsong,GAO Ruihua,et al.Combination of experimental and theoretical investigations of MnOx/Ce0.9Zr0.1O2 nanorods for selective catalytic reduction of NO with ammonia[J].The Journal of Physical Chemistry C,2013,117(19):9999-10006.
[7] GUPTA A,WAGHMARE U V,HEGDE M S.Correlation of oxygen storage capacity and structural distortion in transition-metal-, noble-metal-,and rare-earth-ion-substituted CeO2 from first principles calculation[J].Chemistry of Materials,2010,22(18):5184-5198.
[8] ETTIREDDY P R,KOTRBA A,SPINKS T,et al.Development of low temperature selective catalytic reduction(SCR)catalysts for future emissions regulations[D].Cincinnati,USA:University of Cincinnati,2014.
[9] POURKHALIL M,MOGHADDAM A Z,RASHIDI A,et al.Synthesis of MnOx/oxidized-MWNTs for abatement of nitrogen oxides[J].Catalysis Letters,2013,143(2):184-192.
[10] POURKHALIL M,MOGHADDAM A Z,RASHIDI A,et al.Preparation of highly active manganese oxides supported on functionalized MWNTs for low temperature NOx reduction with NH3[J].Applied Surface Science,2013,279:250-259.
[11] LEE S M,PARK K H,HONG S C.MnOx/CeO2-TiO2 mixed oxide catalysts for the selective catalytic reduction of NO with NH3 at low temperature[J].Chemical Engineering Journal, 2012, 195-196:323-331.
[12] SULTANA A,SASAKI M,HAMADA H.Influence of support on the activity of Mn supported catalysts for SCR of NO with ammonia[J].Catalysis Today,2012,185(1):284-289.
[13] SULTANA A,NANBA T,SASAKI M,et al.Selective catalytic reduction of NOx with NH3over different copper exchanged zeolites in the presence of decane[J].Catalysis Today,2011,164(1):495-499.
[14] KARAMI A,SALEHI V.The influence of chromium substitution on an iron-titanium catalyst used in the selective catalytic reduction of NO[J].Journal of Catalysis,2012,292:32-43.
[15] MA Z R,WENG D,WU X D,et al.A novel NbCe/WOx-TiO2catalyst with high NH3-SCR activity and stability[J].Catalysis Communications,2012,27:97-100.
[16] MALPARTIDA I,MARIE O,BAZIN P,et al.The NO/NOxratio effect on the NH3-SCR efficiency of a commercial automotive Fe-zeolite catalyst studied by operando IR-MS[J].Applied Catalysis B:Environmental,2012,113-114:52-60.