两级烟气脱硝除尘器及脱硝工艺研究
摘要
燃煤电厂烟气中含有大量的飞灰,所含的飞灰易造成SCR反应器中的催化剂磨损和中毒,缩短催化剂使用寿命,增加运行成本,降低装置的稳定性和可靠性。需在省煤器出口和SCR反应器之间增加一个预除尘处理器,进行烟气的预处理,除去部分粉尘,减缓催化剂的失活,提高燃煤电厂烟气的脱硝效率,降低氮氧化物的排放,减小对环境的污染。
本研究采用通用计算流体力学软件Fluent对新型除尘器内部的气固两相流进行三维数值模拟,并对流场的阻力损失进行了分析。采用离散相模型(DPM),模拟固体颗粒运动轨迹,并对固体颗粒的除尘效率进行分析。通过对五种除尘器结构的比较分析得出:Ⅴ型结构的除尘效率是最佳的,且阻力损失也在100Pa以内。根据相似原理,分析了模拟阻力损失和除尘效率的相似条件,设计了前置预除尘装置实物与模型5:1的冷态物理模型,并建立模型实验系统。实验结果表明:随着烟气流速的增加,阻力损失增大,除尘效率降低。在流速为5.8m/s时,Ⅴ型结构的综合除尘效率达到37.64%,且阻力损失为118Pa。模拟与实验的最佳结构是一致的。因此,数值模拟与实验结果吻合良好。
为了验证飞灰对SCR反应器中催化剂的影响,建立了SCR脱硝实验装置。在参数可控及较理想的气体条件下,考察飞灰浓度和SO2浓度对SCR脱硝性能的影响,实验结果表明:SO2对烟气脱硝效率影响不大,而飞灰对烟气的脱硝效率影响较明显,随着飞灰浓度的增加,脱硝效率降低。当飞灰浓度为60g/m3时,脱硝效率只有75.3%,所以加载预除尘器是必要的。
Coal-fired power plant gas contains large amounts of fly ash, which cause SCR catalyst reactor wear and poisoning, shorten catalyst life and increase operating costs and reduce the stability and reliability of device. In the economizer between exports and SCR reactor, a pre-removal processor was installed for gas pretreatment to remove some dust, to slow down the deactivation of catalyst, to improve coal-fired power plant flue gas denitration efficiency and reduce nitrogen oxide matter emissions, and to reduce pollution of the environment.
Fluent,a general computational fluid dynamics software, is used on the gas-solid flow in the new filter to make the three-dimensional numerical simulation, and to analyze the flow resistance losses. Discrete phase model (DPM) was applied to simulate the trajectory of solid particles, and the collection efficiency of solid particles was analyzed. Through comparative analysis of five precipitator obtained:Ⅴstructure of the collection efficiency is the best, and the resistance loss is also less than 100Pa. According to similarity theory, analyzed of the simulation pressure drop and the similar conditions of the collection efficiency, designed Cold physical model, One-fifth of Pre-kind pre-dust device, and model the experimental system. The results show that: with the increase of gas flow rate, the increase of the pressure drop, the reduce of the collection efficiency. At a flow rate of 5.8m/s when,Ⅴstructure of the integrated dust removal efficiency is 37.64%, and the resistance loss is 118Pa. Simulation and experiment’s best structure is the same.Therefore, numerical simulation and experimental results are in good agreement.
In order to verify the influence of the fly ash to the SCR catalyst reactor, SCR DeNOx experimental apparatus is established . In the controllable and the ideal gas conditions, study the influence of fly ash concentration and SO2 concentration to the SCR DeNOx performance, the experimental results show that: SO2 efficiency of flue gas denitration has little effect on the smoke and ash significantly influenced the denitration efficiency. With the increase of the concentration of fly ash,the denitration efficiency reduces. When the fly ash concentration is 60g/m3, the denitration efficiency is only 75.3%, so it is necessary to load the pre-filter.
本研究采用通用计算流体力学软件Fluent对新型除尘器内部的气固两相流进行三维数值模拟,并对流场的阻力损失进行了分析。采用离散相模型(DPM),模拟固体颗粒运动轨迹,并对固体颗粒的除尘效率进行分析。通过对五种除尘器结构的比较分析得出:Ⅴ型结构的除尘效率是最佳的,且阻力损失也在100Pa以内。根据相似原理,分析了模拟阻力损失和除尘效率的相似条件,设计了前置预除尘装置实物与模型5:1的冷态物理模型,并建立模型实验系统。实验结果表明:随着烟气流速的增加,阻力损失增大,除尘效率降低。在流速为5.8m/s时,Ⅴ型结构的综合除尘效率达到37.64%,且阻力损失为118Pa。模拟与实验的最佳结构是一致的。因此,数值模拟与实验结果吻合良好。
为了验证飞灰对SCR反应器中催化剂的影响,建立了SCR脱硝实验装置。在参数可控及较理想的气体条件下,考察飞灰浓度和SO2浓度对SCR脱硝性能的影响,实验结果表明:SO2对烟气脱硝效率影响不大,而飞灰对烟气的脱硝效率影响较明显,随着飞灰浓度的增加,脱硝效率降低。当飞灰浓度为60g/m3时,脱硝效率只有75.3%,所以加载预除尘器是必要的。
Coal-fired power plant gas contains large amounts of fly ash, which cause SCR catalyst reactor wear and poisoning, shorten catalyst life and increase operating costs and reduce the stability and reliability of device. In the economizer between exports and SCR reactor, a pre-removal processor was installed for gas pretreatment to remove some dust, to slow down the deactivation of catalyst, to improve coal-fired power plant flue gas denitration efficiency and reduce nitrogen oxide matter emissions, and to reduce pollution of the environment.
Fluent,a general computational fluid dynamics software, is used on the gas-solid flow in the new filter to make the three-dimensional numerical simulation, and to analyze the flow resistance losses. Discrete phase model (DPM) was applied to simulate the trajectory of solid particles, and the collection efficiency of solid particles was analyzed. Through comparative analysis of five precipitator obtained:Ⅴstructure of the collection efficiency is the best, and the resistance loss is also less than 100Pa. According to similarity theory, analyzed of the simulation pressure drop and the similar conditions of the collection efficiency, designed Cold physical model, One-fifth of Pre-kind pre-dust device, and model the experimental system. The results show that: with the increase of gas flow rate, the increase of the pressure drop, the reduce of the collection efficiency. At a flow rate of 5.8m/s when,Ⅴstructure of the integrated dust removal efficiency is 37.64%, and the resistance loss is 118Pa. Simulation and experiment’s best structure is the same.Therefore, numerical simulation and experimental results are in good agreement.
In order to verify the influence of the fly ash to the SCR catalyst reactor, SCR DeNOx experimental apparatus is established . In the controllable and the ideal gas conditions, study the influence of fly ash concentration and SO2 concentration to the SCR DeNOx performance, the experimental results show that: SO2 efficiency of flue gas denitration has little effect on the smoke and ash significantly influenced the denitration efficiency. With the increase of the concentration of fly ash,the denitration efficiency reduces. When the fly ash concentration is 60g/m3, the denitration efficiency is only 75.3%, so it is necessary to load the pre-filter.
引文
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[3] Art Fermendez, Jost OL Wendt, Klaus R G Hein, Wang Shengjun, Mark L Witten.Inhalation health effects of fine particles from the CO2 combustion of coal and refuse derived fuel. Chemosphere[J], 2003, 51:1129-1137.
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[6] Lisi L,Lasorella G,Malloggi Setal.Single and Combined Deactivating Effect of Alkali Metals and HCl on Commercial SCR Catalysts[J]. Applied Catalysis B:Environ,2004,50 (4):251-258.
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[36]管一明,胡宇峰.火电厂高飞灰布置SCR系统的主要组成和设备[J].电力环境保护,2004,4:25～27.
[37]沈伯雄,施建伟,杨婷婷等.选择性催化还原脱氮催化剂的再生及其应用评述[J].化工进展, 2008,27:64-67.
[38]刘建濮,高晓成,黎耘.中国燃煤SCR的高灰考虑.第二届中国国际脱硫脱硝技术与设备展览及技术研讨会论文集[J],北京:2006.
[39] L.Nova,L.Lietti,L.Casagrande,L.Dall etc.Characterization and reactivity of TiO2 supported MoO3 De-NOx SCR catalysis [J],Applied Catalysis B:Environmental,1998,17:245-25.
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[50]王树荣,王琦,王建华等.选择性催化还原脱硝技术在燃煤电厂的应用和发展[J].电站系统工程,2005,21:11-13.
[2] Dai Haixia, Song Weimin. Healthy effect of PM2.5 in atmosphere. Foreign Medical Sciences: Section Hy giene[J],2001,28 (5):299-303.
[3] Art Fermendez, Jost OL Wendt, Klaus R G Hein, Wang Shengjun, Mark L Witten.Inhalation health effects of fine particles from the CO2 combustion of coal and refuse derived fuel. Chemosphere[J], 2003, 51:1129-1137.
[4] Chen J P,Yang R T.Mechanism of Poisoning of the V2O5/TiO2 Catalyst for t he Reduction of NO by NH3[J].Journal of Catalysis,1990,125:411-420.
[5] Larsson A C, Einvall J,Andersson A etal.Targeting by Comparison with Laboratory Experiments the SCR Catalyst Deactivation Process by Potassium and Zinc Salts in a Large scale Biomass Combustion Boiler[J].Energy and Fuels,2006,20:1398-1405.
[6] Lisi L,Lasorella G,Malloggi Setal.Single and Combined Deactivating Effect of Alkali Metals and HCl on Commercial SCR Catalysts[J]. Applied Catalysis B:Environ,2004,50 (4):251-258.
[7]吴宁,宋蔷,李水清等.SCR烟气脱硝过程中SO2和SO3的测量[J].煤炭转化,2006,29(2):84-87.
[8] Crocker C R,Benson S A,Laumb J D. SCR Catalyst Blinding due to Sodium and Calcium Sulfate Formation ,Prepr pap-AmChem Soc ,Div[J].Fuel Chem,2004,49(1):169-173.
[9] Laumb JD,Benson SA.Bench-and Pilot-scale Studies of SCR Catalyst Blinding[C]. Proceeding of Power Production in the 21st Century:Impacts of Fuel Quality and Operations.United Engineering Foundation,Snowbird,UT,2001.
[10]云端,宋蔷,姚强等.V2O5-WO3/TiO2 SCR催化剂的失活机理及分析[J].煤炭转化, 2009, 32(1): 91-96.
[11]张殿印,王纯.除尘器手册[M]北京:化学工业出版社,2005.
[12]唐敬麟,张禄虎.除尘装置系统及设备设计选用手册[M]北京:化学工业出版社,2004.
[13]付中斌,方修睦.XGB型惯性除尘器的研究[J]应用能源技术1996 3:10-14.
[14]张殿印,顾海根.回流式惯性除尘器技术新进展[J]环境科学与技术2000,3:45-48.
[15]楚建华,刘宗明,刘福田,邓新桂.SEU型惯性除尘器的应用研究[J]山东建材, 2002, 23(5): 27- 29.
[16]徐云杰.惯性旋风体逆流式颗粒层除尘器[J]现代制造工程2006,7:117-119.
[17]张强.燃煤电站SCR烟气脱硝技术及工程应用[M].北京:化学工业出版社,2007,7.
[18]杨卫娟,周俊虎,刘建忠等.选择性催化还原SCR脱硝技术在电站锅炉的应用[J].热力发电, 2005,9:10-14.
[19]王杭州. SCR对脱硝效率及SO2转化影响分析[J].电力科学与工程,2008,24(5)17-21.
[20]陈海林,宋新南,江海斌,崔志坤,张国芳.SCR脱硝性能影响因素及维护[J].山东建筑大学学报, 2008,23(2)145-149.
[21] Makoto Inomata, Aklra Mlvamoto, Toshlaki Ui, etc, Activities of V2O5/TiO2 and V2O5/A12O3 Catalysts for the Reduction of NO and NH3 in the Presence of O2 [J].Ind. Eng.Chem.Prod. Res. Dev. 1982,21:424-428.
[22] Pio Forzatti, Daniele Bardini, Lorenzo Sighicelli.Preparation and Characterization of Extrude Monolithic Ceremai Catalysts[J].Catalysis Today, 1998, 41:87-94.
[23] G Ramis,Li Yi,G Busca.Ammonia activation over catalysts for the selective catalytic reduction of NOx and the selective catalytic oxidation of NH3: an FTIR study[J].Catalysis Today, 1996, 28: 373-380.
[24] Hyoung Lim Koh, Sang Ho and Kyung Lim Kim.The Effect of MoO3 Addition to V2O5/A12O3 Catalysts for The Selective Catalytic Reduction of NO by NH3 [J]. React.Catal Lett.2000,71: 239-244.
[25] Maria Cristina Paganini, Lorenzo Dall Acqua, Elio Giamello,etc,An EPR study of the surface chemistry of the V2O5-WO3/TiO2 catalyst: Redox behavior and state of V(IV)[J]. Journal of Catalysis, 1997,166:195-205.
[26] P.Ciambelli,M.E.Foriuna,D.Sannino and A.Baldacci.The influence of sulphate on the catalytic properties of V2O5-TiO2 and WO3-TiO2 in the reduction of nitric oxide with ammonia[J], Catalysis Today,1996,29:161-164.
[27]田柳青.氨选择性还原脱除氮氧化物工业催化剂研究[D].华南理工大学硕士论文,2002.
[28]宣小平,李术元.以飞灰为载体的金属氧化物催化剂脱硝研究[J].环境科学学报,2003, 23:33- 38.
[29]钟秦,曲红霞.NH3选择性催化还原NOx的实验研究[J].南京理工大学学报,2002,26:68-71.
[30]王福军.计算流体动力学分析—CFD软件原理与应用[M].北京:清华大学出版社,2004.
[31]韩占忠,王敬,兰小平.FLUENT流体工程仿真计算实例与应用[M].北京理工大学出版社,2004.
[32] fluent Inc. GAMBIT Modeling Guide [M ].[ S.L.] Fluent Inc,2003.
[33] LAUNDER B E,SPALDIN G D B.Lectures in mathematical models of turbulence [M]. London, UK:Academic Press,1972:127-133.
[34]高家锐主编.动量、热量、质量传输原理[M].重庆:重庆大学出版社,1987.
[35]陈代宾.燃煤电厂选择性催化脱硝工艺的实践与探讨.电力环境保护,2003,19(3):21～23.
[36]管一明,胡宇峰.火电厂高飞灰布置SCR系统的主要组成和设备[J].电力环境保护,2004,4:25～27.
[37]沈伯雄,施建伟,杨婷婷等.选择性催化还原脱氮催化剂的再生及其应用评述[J].化工进展, 2008,27:64-67.
[38]刘建濮,高晓成,黎耘.中国燃煤SCR的高灰考虑.第二届中国国际脱硫脱硝技术与设备展览及技术研讨会论文集[J],北京:2006.
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