省煤器灰斗结构对电站煤粉锅炉烟气的预除尘性能研究
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摘要
近年来,环境保护越来越受到重视。火力电站的燃煤锅炉在生产时产生大量的废气,包括氮氧化物、硫氧化物、飞灰等,因此,火力电站是颗粒污染物的重要来源之一。目前,电除尘器是电站的主要除尘设备之一,当烟气没有经过预除尘时烟气中粉尘颗粒的含量较多,电除尘器的除尘效率较低,能量损失大。为提高电站的除尘效率,减少能量损失,减少烟气的颗粒物对于空气预热器等的磨损,在省煤器下增设灰斗对烟气进行预除尘,能够很好的满足生产要求。
为较大限度地提高除尘效率、减少压力损失,对省煤器灰斗系统进行优化,包括对灰斗的形状以及在转向室中所布置的导流板。通过冷态锅炉实验与数值模拟相结合的方法研究系统的性能,研究过程中对于冷态实验的搭建及改进提出了一些建议,并验证了模拟的可行性。实验中为保证流动相似采用了欧拉相似准则,在满足第二自模区要求的同时能够降低对动力设备的要求,减少风机的给风量。
本文采用了商业软件fluent,应用颗粒轨道模型对系统进行数值模拟计算,并与实验结果进行对比。通过对多种情况下的气相流场性能、颗粒运动轨迹、除尘效率及压力损失的分析,发现导流板的布置位置对于系统的性能有很大的影响。研究发现,颗粒的大小以及颗粒进入系统的位置对于颗粒的运动轨迹有着重要影响,直接影响系统的除尘效率,初始位置距离出口较远及直径较大的颗粒容易被灰斗系统所收集；导流板可以优化出口的流场分布,减轻由于速度分布不均而对烟道某一侧面造成的磨损；导流板的角度、位置、数量等对于系统的性能有重大影响,且存在一定的规律,通过这些规律能够很快为实际生产提供一个可行的方案。
Recently, more and more attention were paid on environmental protection. A large number of emissions, including Nitrogen oxides, Sulfur oxides and fly ash, were produced during Coal-fired power stations operation. The power plants were the sources of particle pollution. The electrostatic precipitator (ESP) was widely used in power plant. But the ESP has low efficiency and needs more energy when it dealt with flue without precollection. In order to increase the separation efficiency and reduce the wear and of air preheater, one easy way is the precollection of fly ash before ESP by adding ash-hoppers downstream the economizer.
To obtain higher separate efficiency with lower pressure loss, it is necessary to optimize the ash-hopper's structure to find reasonable arrangements for the baffles which were used to change the flow direction of flow gas in the flue. The results of system performance were obtained from the iso-thermal experiments and simulation. There were some advises mentioned for the iso-thermal model experiment, and the rationalization of the simulation result were verified by the iso-thermal experiments. The Euler similarity criterion was adopted in experiment, so the iso-thermal experiments could enter the second self-modeling region to be similar to the flow characteristics of prototype. In this case, less energy was needed for the power of experiment and less air from fans.
The numerical simulation was carried out by the commercial CFD software, Fluent. It was found that the system structure, especially the baffles and the baffle arrangements, is important to the performance. The most suitable structure was found through simulation results including the velocity and pressure fields of gas phase, the pathlines of particles, the pressure drop and the separation efficiency. The diameter and the release location of particles had great influence to their pathlines. Particles far from the exit and with large diameter were easily trapped. The baffles could used to optimize the velocity field, decreasing the wear of flue from particles. The angles, arrangement, quantity of baffles were all important for the system performance. There were some laws for the system performance when they changed. Though the laws, the most valuable structure was picked quickly.
为较大限度地提高除尘效率、减少压力损失,对省煤器灰斗系统进行优化,包括对灰斗的形状以及在转向室中所布置的导流板。通过冷态锅炉实验与数值模拟相结合的方法研究系统的性能,研究过程中对于冷态实验的搭建及改进提出了一些建议,并验证了模拟的可行性。实验中为保证流动相似采用了欧拉相似准则,在满足第二自模区要求的同时能够降低对动力设备的要求,减少风机的给风量。
本文采用了商业软件fluent,应用颗粒轨道模型对系统进行数值模拟计算,并与实验结果进行对比。通过对多种情况下的气相流场性能、颗粒运动轨迹、除尘效率及压力损失的分析,发现导流板的布置位置对于系统的性能有很大的影响。研究发现,颗粒的大小以及颗粒进入系统的位置对于颗粒的运动轨迹有着重要影响,直接影响系统的除尘效率,初始位置距离出口较远及直径较大的颗粒容易被灰斗系统所收集；导流板可以优化出口的流场分布,减轻由于速度分布不均而对烟道某一侧面造成的磨损；导流板的角度、位置、数量等对于系统的性能有重大影响,且存在一定的规律,通过这些规律能够很快为实际生产提供一个可行的方案。
Recently, more and more attention were paid on environmental protection. A large number of emissions, including Nitrogen oxides, Sulfur oxides and fly ash, were produced during Coal-fired power stations operation. The power plants were the sources of particle pollution. The electrostatic precipitator (ESP) was widely used in power plant. But the ESP has low efficiency and needs more energy when it dealt with flue without precollection. In order to increase the separation efficiency and reduce the wear and of air preheater, one easy way is the precollection of fly ash before ESP by adding ash-hoppers downstream the economizer.
To obtain higher separate efficiency with lower pressure loss, it is necessary to optimize the ash-hopper's structure to find reasonable arrangements for the baffles which were used to change the flow direction of flow gas in the flue. The results of system performance were obtained from the iso-thermal experiments and simulation. There were some advises mentioned for the iso-thermal model experiment, and the rationalization of the simulation result were verified by the iso-thermal experiments. The Euler similarity criterion was adopted in experiment, so the iso-thermal experiments could enter the second self-modeling region to be similar to the flow characteristics of prototype. In this case, less energy was needed for the power of experiment and less air from fans.
The numerical simulation was carried out by the commercial CFD software, Fluent. It was found that the system structure, especially the baffles and the baffle arrangements, is important to the performance. The most suitable structure was found through simulation results including the velocity and pressure fields of gas phase, the pathlines of particles, the pressure drop and the separation efficiency. The diameter and the release location of particles had great influence to their pathlines. Particles far from the exit and with large diameter were easily trapped. The baffles could used to optimize the velocity field, decreasing the wear of flue from particles. The angles, arrangement, quantity of baffles were all important for the system performance. There were some laws for the system performance when they changed. Though the laws, the most valuable structure was picked quickly.
引文
[1]彭苏萍.中国煤炭资源开发与环境保护[J].科技导报,2009,17：1-2
[2]Yang Y.P., Guo X., Wang N.L. Power generation from pulverized coal in China[J]. Energy, 2010,35(11):4336-4338
[3]Yao Q., S.-Q. Li, H.-W. Xu, J.-K. Zhuo, Q. Song. Studies on formation and control of combustion particulate matter in China [J]. Energy,2009,34(9):1296-1309
[4]周新刚,刘志超,路春美,巩志强.燃煤电厂锅炉飞灰含碳量影响因素分析及对策[J].节能,2005,9：45-47
[5]Moumakwa D.O., Marcus K. Tribology in coal-fired power plants [J]. Tribology International,2005,38(9):805-811
[6]周屈兰,窦文宇,徐通模,惠世恩.大容量锅炉灰斗分离特性的实验研究[J].动力工程,1999,9：6-8
[7]周屈兰,周月桂,徐通模,惠世恩.大容量锅炉灰斗改型的实验研究[J].西安交通大学学报,1999,33(2)：25-29
[8]Sheng C.D., Li Y., Liu X.W., Yao H., Xu M. Ash particle formation during O2/CO2 combustion of pulverized coals [J]. Fuel Processing Technology,2007,88(11):1021-1028
[9]王文荣.浅谈电厂锅炉烟气除尘工程的应用[J].四川建材,2007,2：63-64
[10]王玉梅.中小型燃煤锅炉使用布袋除尘器应注意的问题[J].节能与环保,2008,5：36-38
[11]孙健.浅谈电除尘器结构概况和注意事项[J].科技创新导报,2009,25：164
[12]邱燃.高温烟气除尘用复合型陶瓷过滤材料的制备及其性能研[D].上海：东华大学,2009：1-10
[13]郭东方.水膜除尘器技术改造总结[J].化肥工业,2009,36(4)：62-64
[14]Toshiyuki S., Mika G., Takahiro U. Performance analysis of US coal-fired power plants by measuring three DEA efficiencies [J]. Energy policy.2010,38:1675-1688
[15]郭小玲,唐晓飞,赵海峰,朱玉明.电袋复合式除尘器的发展趋势[J].华北电力技术.2008.9：50-54
[16]Tommy R. D., Johnstone H. F. Gaseous fluidization of solid particles [J]. Chem. Eng. Prog, 1952,48(5):220-226
[17]Alexander K., Efstathios E. Michaelides. An analytical approach for the closure equations of gas-solid flows with inter-particle collisions [J]. International Journal of Multiphase Flow,2004,30(2):159-180
[18]杨勇林.循环流化床下行管内气固两相流流体力学模型与数值模拟.化学反应工程与工艺[J],1995,11(3)：217-225
[19]车得福,李会雄.多想流及其应用[M].西安：西安交通大学出版社,2007
[20]徐江荣,周俊虎.两项湍流流动PDF理论与数值模拟[M].北京：科学出版社,2008
[21]周力行.湍流两相流动与燃烧的数值模拟[M].北京：清华大学出版社,1991
[22]Druzhinin O. A. and Elghobashi S. E. A Lagrangian-Eulerian Mapping Solver for Direct Numerical Simulation of Bubble-Laden Turbulent Shear Flows Using the Two-Fluid Formulation [J]. Journal of Computational Physics,1999,154(1):174-196
[23]S Elghobashi., Abou-Arab T., Rizk M. and Mostafa A. Prediction of the particle-laden jet with a two-equation turbulence model [J]. International Journal of Multiphase Flow,1984, 10(6):697-710
[24]Wang Q.Z., Kyle D. Squires, Simonin O. Large eddy simulation of turbulent gas-solid flows in a vertical channel and evaluation of second-order models [J]. International Journal of Heat and Fluid Flow,1998,19(5):505-511
[25]Veynante D., Vervisch L. Turbulent combustion modeling [J]. Progress in Energy and Combustion Science,2002,28(3):193-266
[26]Orszag S.A., Yakhot V., Flannery W.S., Boysan F., Choudhury D., Maruzewski J. and Patel B. Renormalization Group Modeling and Turbulence Simulations [C]. In International Conference on Near-Wall Turbulent Flows. Arizona,1993:15-17
[27]Jean-Pierre Minier, Eric Peirano. The pdf approach to turbulent polydispersed two-phase flow [J]. Physics Reports,2001,352(1-3):1-214
[28]Chibbaro S., Minier J. P. Langevin PDF simulation of particle deposition in a turbulent pipe flow [J]. Journal of Aerosol Science,2008,39(7):555-571
[29]冯俊凯,沈幼庭,杨瑞昌.锅炉原理及计算[M].北京：科学出版社,2003
[30]郑先国.220t/h煤粉炉低NOx再燃技术冷态试验研究[D].重庆：重庆大学,2003：22-27
[31]孔珑.两相流体力学[M].北京：高等教育出版社,2004
[32]李锋.切圆锅炉模型中旋转气流的试验研究[D].武汉：华中科技大学,2007：9-11
[33]Spalart P., Allmaras S. A one-equation turbulence model for aerodynamic flows [R]. Technical Report AIAA-92-0439. American Institute of Aeronautics and Astronautics. 1992
[34]Walters D.-K., Cokljat D. A three-equation eddy-viscosity model for reynolds-averaged navier-stokes simulations of transitional flows [J]. Fluids Engineering,2008,12:130
[35]Shih T.-H., Liou W. W, Shabbir A., Yang Z., and Zhu J. A New k-ε Eddy-Viscosity Model for High Reynolds Number Turbulent Flows-Model Development and Validation [J]. Computers Fluids.1995.24(3):227-238
[36]Chapman S., Cowling T. G. The Mathematical Theory of Non-uniform Gases. Cambridge: Cambridge Mathematic Library,1970
[37]Jenkins J.T., and Richman M.W. Arch. Ratio. Mech [J]. Anal,1985,87:355-377
[38]Grad, Comm H. Pure Appl [J]. Math,1949,2(4):331-407
[39]王顺森,刘观伟,毛靖儒.超常参数条件下汽固两相流动的相似与模化方法探究[J].西安交通大学学报,2007,41(3)：279-283
[40]Ergun S. Fluid flow through packed columns [J]. Chemical Engineering,1952,48:89-94
[41]Kuipers, Duin V., Beckum V., Swaaij V. A numerical model of gas-fluidized beds [J]. Chemical Engineering Science,1992:47-48
[42]Hoef M.A., Annaland M. S., Kuipers J. A. M. Computational fluid dynamics for dense gas-solid fluidized beds:a multi-scale modeling strategy [J]. Chemical Engineering Science,2004,59:5157-5165
[43]Wen Y.C., Yu Y.H. Mechanics of Fluidization [J]. Chemical Engineering Progress Symposium Series.1966,62:100-111
[44]Hill R.J., Koch D.L., Ladd J.C. Moderate-Reynolds-numbers flows in ordered and random arrays of spheres [J]. Journal of Fluid Mechanics,2001,448:243-278
[45]BeetstraR., Hoef M.A., Kuipers J.A.M. Numerical study of segregation using new drag force correlation for polydisperse systems derived from lattice-Boltzmann simulations [J]. Chemical Engineering Science,2007,62(1-2):246-255
[46]Zhou Q., Leschziner M. A. Technical report.8th Turbulent Shear Flows Symp. Munich. 1991
[47]Patanker S.V., Spalding D.B. A calculation processure for heat, mass and momentum transfer in three-dimensional parabolic flows [J]. Int J Heat Mass Transfer,1972: 1787-1806
[48]汪林.旋风分离器气固两相流数值模拟及性能分析[D].哈尔滨：哈尔滨工业大学,2007：22-25
[49]陶文铨.数值传热学(第二版)[M].西安：西安交通大学出版社,2001
[50]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,2004
[51]周光垌,严宗毅,许世雄,章克本.流体力学[M].北京：高等教育出版社,2000
[52]郑钢镖,康天合,柴肇云,尹志宏.运用Rosin-Rammler分布函数研究煤尘粒径分布规律[J].太原理工大学学报,2006,37(3)：317-319
[2]Yang Y.P., Guo X., Wang N.L. Power generation from pulverized coal in China[J]. Energy, 2010,35(11):4336-4338
[3]Yao Q., S.-Q. Li, H.-W. Xu, J.-K. Zhuo, Q. Song. Studies on formation and control of combustion particulate matter in China [J]. Energy,2009,34(9):1296-1309
[4]周新刚,刘志超,路春美,巩志强.燃煤电厂锅炉飞灰含碳量影响因素分析及对策[J].节能,2005,9：45-47
[5]Moumakwa D.O., Marcus K. Tribology in coal-fired power plants [J]. Tribology International,2005,38(9):805-811
[6]周屈兰,窦文宇,徐通模,惠世恩.大容量锅炉灰斗分离特性的实验研究[J].动力工程,1999,9：6-8
[7]周屈兰,周月桂,徐通模,惠世恩.大容量锅炉灰斗改型的实验研究[J].西安交通大学学报,1999,33(2)：25-29
[8]Sheng C.D., Li Y., Liu X.W., Yao H., Xu M. Ash particle formation during O2/CO2 combustion of pulverized coals [J]. Fuel Processing Technology,2007,88(11):1021-1028
[9]王文荣.浅谈电厂锅炉烟气除尘工程的应用[J].四川建材,2007,2：63-64
[10]王玉梅.中小型燃煤锅炉使用布袋除尘器应注意的问题[J].节能与环保,2008,5：36-38
[11]孙健.浅谈电除尘器结构概况和注意事项[J].科技创新导报,2009,25：164
[12]邱燃.高温烟气除尘用复合型陶瓷过滤材料的制备及其性能研[D].上海：东华大学,2009：1-10
[13]郭东方.水膜除尘器技术改造总结[J].化肥工业,2009,36(4)：62-64
[14]Toshiyuki S., Mika G., Takahiro U. Performance analysis of US coal-fired power plants by measuring three DEA efficiencies [J]. Energy policy.2010,38:1675-1688
[15]郭小玲,唐晓飞,赵海峰,朱玉明.电袋复合式除尘器的发展趋势[J].华北电力技术.2008.9：50-54
[16]Tommy R. D., Johnstone H. F. Gaseous fluidization of solid particles [J]. Chem. Eng. Prog, 1952,48(5):220-226
[17]Alexander K., Efstathios E. Michaelides. An analytical approach for the closure equations of gas-solid flows with inter-particle collisions [J]. International Journal of Multiphase Flow,2004,30(2):159-180
[18]杨勇林.循环流化床下行管内气固两相流流体力学模型与数值模拟.化学反应工程与工艺[J],1995,11(3)：217-225
[19]车得福,李会雄.多想流及其应用[M].西安：西安交通大学出版社,2007
[20]徐江荣,周俊虎.两项湍流流动PDF理论与数值模拟[M].北京：科学出版社,2008
[21]周力行.湍流两相流动与燃烧的数值模拟[M].北京：清华大学出版社,1991
[22]Druzhinin O. A. and Elghobashi S. E. A Lagrangian-Eulerian Mapping Solver for Direct Numerical Simulation of Bubble-Laden Turbulent Shear Flows Using the Two-Fluid Formulation [J]. Journal of Computational Physics,1999,154(1):174-196
[23]S Elghobashi., Abou-Arab T., Rizk M. and Mostafa A. Prediction of the particle-laden jet with a two-equation turbulence model [J]. International Journal of Multiphase Flow,1984, 10(6):697-710
[24]Wang Q.Z., Kyle D. Squires, Simonin O. Large eddy simulation of turbulent gas-solid flows in a vertical channel and evaluation of second-order models [J]. International Journal of Heat and Fluid Flow,1998,19(5):505-511
[25]Veynante D., Vervisch L. Turbulent combustion modeling [J]. Progress in Energy and Combustion Science,2002,28(3):193-266
[26]Orszag S.A., Yakhot V., Flannery W.S., Boysan F., Choudhury D., Maruzewski J. and Patel B. Renormalization Group Modeling and Turbulence Simulations [C]. In International Conference on Near-Wall Turbulent Flows. Arizona,1993:15-17
[27]Jean-Pierre Minier, Eric Peirano. The pdf approach to turbulent polydispersed two-phase flow [J]. Physics Reports,2001,352(1-3):1-214
[28]Chibbaro S., Minier J. P. Langevin PDF simulation of particle deposition in a turbulent pipe flow [J]. Journal of Aerosol Science,2008,39(7):555-571
[29]冯俊凯,沈幼庭,杨瑞昌.锅炉原理及计算[M].北京：科学出版社,2003
[30]郑先国.220t/h煤粉炉低NOx再燃技术冷态试验研究[D].重庆：重庆大学,2003：22-27
[31]孔珑.两相流体力学[M].北京：高等教育出版社,2004
[32]李锋.切圆锅炉模型中旋转气流的试验研究[D].武汉：华中科技大学,2007：9-11
[33]Spalart P., Allmaras S. A one-equation turbulence model for aerodynamic flows [R]. Technical Report AIAA-92-0439. American Institute of Aeronautics and Astronautics. 1992
[34]Walters D.-K., Cokljat D. A three-equation eddy-viscosity model for reynolds-averaged navier-stokes simulations of transitional flows [J]. Fluids Engineering,2008,12:130
[35]Shih T.-H., Liou W. W, Shabbir A., Yang Z., and Zhu J. A New k-ε Eddy-Viscosity Model for High Reynolds Number Turbulent Flows-Model Development and Validation [J]. Computers Fluids.1995.24(3):227-238
[36]Chapman S., Cowling T. G. The Mathematical Theory of Non-uniform Gases. Cambridge: Cambridge Mathematic Library,1970
[37]Jenkins J.T., and Richman M.W. Arch. Ratio. Mech [J]. Anal,1985,87:355-377
[38]Grad, Comm H. Pure Appl [J]. Math,1949,2(4):331-407
[39]王顺森,刘观伟,毛靖儒.超常参数条件下汽固两相流动的相似与模化方法探究[J].西安交通大学学报,2007,41(3)：279-283
[40]Ergun S. Fluid flow through packed columns [J]. Chemical Engineering,1952,48:89-94
[41]Kuipers, Duin V., Beckum V., Swaaij V. A numerical model of gas-fluidized beds [J]. Chemical Engineering Science,1992:47-48
[42]Hoef M.A., Annaland M. S., Kuipers J. A. M. Computational fluid dynamics for dense gas-solid fluidized beds:a multi-scale modeling strategy [J]. Chemical Engineering Science,2004,59:5157-5165
[43]Wen Y.C., Yu Y.H. Mechanics of Fluidization [J]. Chemical Engineering Progress Symposium Series.1966,62:100-111
[44]Hill R.J., Koch D.L., Ladd J.C. Moderate-Reynolds-numbers flows in ordered and random arrays of spheres [J]. Journal of Fluid Mechanics,2001,448:243-278
[45]BeetstraR., Hoef M.A., Kuipers J.A.M. Numerical study of segregation using new drag force correlation for polydisperse systems derived from lattice-Boltzmann simulations [J]. Chemical Engineering Science,2007,62(1-2):246-255
[46]Zhou Q., Leschziner M. A. Technical report.8th Turbulent Shear Flows Symp. Munich. 1991
[47]Patanker S.V., Spalding D.B. A calculation processure for heat, mass and momentum transfer in three-dimensional parabolic flows [J]. Int J Heat Mass Transfer,1972: 1787-1806
[48]汪林.旋风分离器气固两相流数值模拟及性能分析[D].哈尔滨：哈尔滨工业大学,2007：22-25
[49]陶文铨.数值传热学(第二版)[M].西安：西安交通大学出版社,2001
[50]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,2004
[51]周光垌,严宗毅,许世雄,章克本.流体力学[M].北京：高等教育出版社,2000
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