燃用超低热值煤泥CFB锅炉U型分离器数值模拟研究
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摘要
以超低热值煤泥为主要燃料的循环流化床锅炉燃烧时,会产生大量飞灰,不合理的U型惯性分离器结构和气动力学参数选择或造成分离后的粗灰集聚于U型惯性分离器底部,使得返料通道堵灰以及结焦问题高频发生;或导致该分离器分离效果低下,增加后级旋风分离器的负担,造成锅炉除尘效率降低。为了提高U型分离器的分离效果,采用计算流体力学FLUENT软件,建立对应的气固两ENREF 1相流模型,颗粒相采用拉格朗日方法,选择相间耦合随机轨道模型,气相湍流模型选择κ-ε模型,模拟了不同挡板深度以及不同质量流量对U型分离器分离效果的影响,并计算出不同挡板深度和不同质量流量时U型分离器的分离效率。计算结果表明,所用方法较好的模拟了U型分离器内固体颗粒的运动状态,颗粒的分离效率并不是随挡板深度或质量流量的增加而增加,而是在一定范围内变化。研究结果在一定程度上对U型分离器的结构优化提供了依据。
When the ultra-low calorific value coal sludge is used as the main fuel in CFB boiler,a large amount of fly ash will be produced undoubtedly. and the unreasonable U-shaped inertial separator structure and aerodynamic parameters will cause the coarse ash to be concentrated at the bottom of the U-shaped inertial separator,which will cause the ash blocking and coking problems in the return channel to occur frequently. The separation efficiency of the separator is low,and the burden of the latter stage cyclone is increased,resulting in the reduction of the dust removal efficiency of the boiler. In order to investigate the paths to improve the separation effect of U-shaped separator,the computational fluid dynamics of FLUENT software is used with corresponding air-solid two phase flow model being set up as the Lagrange method being used particle phase,the k-ε turbulent model being chosen for air phase,The effects of different baffle depth and mass flow rate on the separation efficiency of U separator were simulated. The separation efficiency of U separator is calculated when different baffle depth and mass flow rate are calculated. The results show that the method can simulate the movement of solid particles in U-shaped separator well. The separation efficiency of particles does not increase with the increase of baffle depth or mass flow rate,but changes within a certain range. The research results provide a basis for optimizing the structure of U separator to a certain extent.
When the ultra-low calorific value coal sludge is used as the main fuel in CFB boiler,a large amount of fly ash will be produced undoubtedly. and the unreasonable U-shaped inertial separator structure and aerodynamic parameters will cause the coarse ash to be concentrated at the bottom of the U-shaped inertial separator,which will cause the ash blocking and coking problems in the return channel to occur frequently. The separation efficiency of the separator is low,and the burden of the latter stage cyclone is increased,resulting in the reduction of the dust removal efficiency of the boiler. In order to investigate the paths to improve the separation effect of U-shaped separator,the computational fluid dynamics of FLUENT software is used with corresponding air-solid two phase flow model being set up as the Lagrange method being used particle phase,the k-ε turbulent model being chosen for air phase,The effects of different baffle depth and mass flow rate on the separation efficiency of U separator were simulated. The separation efficiency of U separator is calculated when different baffle depth and mass flow rate are calculated. The results show that the method can simulate the movement of solid particles in U-shaped separator well. The separation efficiency of particles does not increase with the increase of baffle depth or mass flow rate,but changes within a certain range. The research results provide a basis for optimizing the structure of U separator to a certain extent.
引文
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[17]刘立鹏,张健潇,王义俊,等. 330 MW循环流化床机组煤泥掺烧自动控制系统优化[J].内蒙古电力技术,2016,34(02):48-52.LIU Lipeng,ZHANG Jianxiao,WANG Yijun,et al. automaticcontrol system optimization on coal slime blending in 330 MWCFB unit[J]. Inner Mongolia Electric Power,2016,34(02):48-52.
[18]殷术贵,吴智恒,张华伟,等.循环流化床锅炉燃烧过程仿真研究[J].广东电力,2016,29(01):8-10.YIN Shugui,WU Zhiheng,ZHANG Huawei,et al. Simulationresearch on combustion process of circulating fluidized bed boiler[J]. Guangdong Electric Power,2016,29(01):8-10.
[19]田秀山,张宏伟.旋风分离器内流场特征的数值模拟[J]浙江电力. 2017,36(11):23-29.TIAN Xiushan,ZHANG Hongwei. Numerical simulation on flowfield characteristics in cyclone separators[J]. Zhejiang ElectricPower,2017,36(11):23-29.
[2]黄中,潘贵涛,张品高,等. 300 MW大型循环流化床锅炉运行分析与发展建议[J].锅炉技术,2014,45(6):35-41.HUANG Zhong,PAN Guitao,ZHANG Pingao,et al. Operatingcondition and development proposal of 300 MW large-scalecirculating fluidized bed boiler[J]. Boiler Technology,2014,45(60):35-41.
[3]莫鑫,黄逸群,向柏祥,等.燃煤循环流化床锅炉中并联分离器的性能实验研究[J].煤炭学报,2016,41(10):2503-2507.HUANG Xin,HUANG Yiqun,XIANG Baixiang,et al. Experimentalstudy on the performance of parallel cyclones in a coal-fired CFBboiler[J]. Journal of China Coal Society,2016,41(10):2503-2507.
[4]刘俊杰.循环流化床锅炉分离器的改造研究[J].山西化工,2018,38(02):143-145.LIU Junjie. Study on the reformation of the separator in a CFBboiler[J]. Shanxi Chemical Industry,2018,38(02):143-145.
[5]王雁珍,亓艳杰,李剑.循环流化床锅炉返料异常的分析及预防调整[J].电站系统工程,2017,33(03):33-34.WANG Yanzhen,QI Yanjie,LI Jian. Analysis and preventiveadjustment of recycle material abnormal in CFB boiler[J]. PowerSystem Engineering,2017,33(03):33-34.
[6]林金辉.中小型循环流化床锅炉分离器改造[J].节能技术,2013,31(05):468-473.LIN Jinhui. Properties research on the transformation of theseparator of middle and small sized CFB[J]. Energy ConservationTechnology,2013,31(05):468-473.
[7]刘洪鹏,王旭东,孙佰仲,等. 75t/h循环流化床锅炉分离器的改造[J].科学技术与工程,2014,14(03):148-151.LIU Hongpeng,WANG Xudong,SUN Baizhong,et al. Separationdevice retorfit of a 75t/h circulating fluidized bed boiler[J].Science Technology and Engineering,2014,14(03):148-151.
[8] PAWE?KOZO?UB,ADAM KLIMANEK,RYSZARD A. BIA?ECKI,etal. Numerical simulation of a dense solid particle flow inside a cycloneseparator using the hybrid euler-lagrange approach[J]. Particuology,2017,31(02):170-180.
[9] HONGPENG LIU,JIAWEI LI,QING WANG. Simulation of gas-solidflow characteristics in a circulating fluidized bed based on acomputational particle fluid dynamics model[J]. PowderTechnology,2017,321(07):132–142.
[10] W. I. MAZYAN,A. AHMADI,J. BRINKERHOFF,et al. Enhancement ofcyclone solid particle separation performance based on geometricalmodification:Numerical analysis[J]. Separation and PurificationTechnology,2018,191(01):276-285.
[11]王雁珍,亓艳杰,李剑.循环流化床锅炉返料异常的分析及预防调整[J].电站系统工程,2017,33(03):33-34.WANG Yanzhen,QI Yanjie,LI Jian. Analysis and preventiveadjustment of recycle material abnormal in CFB boiler[J]. PowerSystem Engineering,2017,33(03):33-34.
[12]刘洪鹏,肖剑波,王敬斌,等.循环流化床气固两相流动数值模拟的研究进展[J].化工机械,2014,41(01):6-8.LIU Hongpeng,XIAO Jianbo,WANG Jingbin,et al. Researchprogress in numerical simulation of gas-solid flow on CFB[J].Chemical Engineering&Machinery,2014,41(01):6-8.
[13]雷蕾,袁隆基.循环流化床锅炉旋风分离器性能特性数值模拟[J].江苏大学学报(自然科学版),2015,36(02):148-152.LEI Lei,YUAN Longji. Numerical simulation on cyclone separatorcharacteristics of circulating fluidized bed boiler[J]. Journal ofJiangsu University(natural science edition),2015,36(02):148-152.
[14]李强.循环流化床锅炉旋风分离器气固两相流动特性及性能研究[D].上海:上海交通大学,2010.
[15]赵立正,原奇鑫,康志忠,等.超临界循环流化床旋风分离器结构优化数值模拟[J].锅炉技术,2016,47(03):31-37.ZHAO Lizheng,YUAN Qixin,KANG Zhizhong,et al. Numericalsimulation and structure optimization of cyclone separator insupercritical circulating fluidized bed[J]. Boiler Technology,2016,47(03):31-37.
[16]王文强,钱进,覃海波,等.基于SPE的660 MW超临界汽轮机阀控方案数值模拟研究[J].电力大数据,2018(03):33-38.WANG Wenqiang,QIAN Jin,QIN Haibo,et al. Study onnumerical simulation for valve control scheme of 660 MWsupercritical steam turbine based on SPE[J]. Power Systems andBig Data,2018(03):33-38.
[17]刘立鹏,张健潇,王义俊,等. 330 MW循环流化床机组煤泥掺烧自动控制系统优化[J].内蒙古电力技术,2016,34(02):48-52.LIU Lipeng,ZHANG Jianxiao,WANG Yijun,et al. automaticcontrol system optimization on coal slime blending in 330 MWCFB unit[J]. Inner Mongolia Electric Power,2016,34(02):48-52.
[18]殷术贵,吴智恒,张华伟,等.循环流化床锅炉燃烧过程仿真研究[J].广东电力,2016,29(01):8-10.YIN Shugui,WU Zhiheng,ZHANG Huawei,et al. Simulationresearch on combustion process of circulating fluidized bed boiler[J]. Guangdong Electric Power,2016,29(01):8-10.
[19]田秀山,张宏伟.旋风分离器内流场特征的数值模拟[J]浙江电力. 2017,36(11):23-29.TIAN Xiushan,ZHANG Hongwei. Numerical simulation on flowfield characteristics in cyclone separators[J]. Zhejiang ElectricPower,2017,36(11):23-29.