涡轮式气流分级机压降分析及流场模拟
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摘要
涡轮式气流分级机是超细铁矿粉的主要生产设备,在分级精度和分级效率上一直不高。为此,结合转轮转速和入口风速匹配关系,对转轮入口速度三角形进行分析,运用CFD流体动力学及力学相对运动理论对叶片间压降进行分析,得出分级轮叶片间速度分布规律。并利用FLUENT软件对不同叶片数结构转轮进行建模和数值模拟。数值模拟结果表明:转轮叶片长宽厚和进风速度对入口处流体的运动速度有直接影响;提高转轮转速能获得更细粒径,但容易造成流场不均匀,降低分级精度;通过适当增加叶片数能改进流体速度的分布规律,从而提升分级效率;提出了增加叶片数的新转轮设计方法,通过数值模拟和物料试验证明该新结构在一定工况下流场分布均匀,分级效率提升。研究结果对涡轮式气流分级机的设计具有一定的指导作用。
Turbine air classifier is the main production equipment for ultrafine iron ore fines, which usually has an inferior classification accuracy and efficiency. To address the problem, in consideration of the relationship between the rotating speed of the impeller and the inlet wind speed, the inlet speed triangle is analyzed. The pressure drop between the blades is analyzed based on CFD fluid dynamics and the theory of relative motion of the mechanics. The FLUENT software is used to model and numerically simulate the impeller with different number of blades. The numerical simulation results show that the length, width and thickness of the impeller blade and the inlet velocity have a direct influence on the velocity at the inlet. Increasing the rotation speed can obtain a finer particle size, but it is easy to cause uneven flow field to reduce the classification accuracy. Proper increase of the number of blades can improve the velocity distribution, thus improve the classification efficiency. A new design method of increasing the number of blades is proposed. The numerical simulation and test prove an evenly distributed flow field under certain working conditions and increased classification efficiency. The study results have a certain guiding effect on the design of the classifier.
Turbine air classifier is the main production equipment for ultrafine iron ore fines, which usually has an inferior classification accuracy and efficiency. To address the problem, in consideration of the relationship between the rotating speed of the impeller and the inlet wind speed, the inlet speed triangle is analyzed. The pressure drop between the blades is analyzed based on CFD fluid dynamics and the theory of relative motion of the mechanics. The FLUENT software is used to model and numerically simulate the impeller with different number of blades. The numerical simulation results show that the length, width and thickness of the impeller blade and the inlet velocity have a direct influence on the velocity at the inlet. Increasing the rotation speed can obtain a finer particle size, but it is easy to cause uneven flow field to reduce the classification accuracy. Proper increase of the number of blades can improve the velocity distribution, thus improve the classification efficiency. A new design method of increasing the number of blades is proposed. The numerical simulation and test prove an evenly distributed flow field under certain working conditions and increased classification efficiency. The study results have a certain guiding effect on the design of the classifier.
引文
[1] REN W J,LIU J X,YU Y.Design of a rotor cage with non-radial arc blades for turbo air classifiers[J].Powder Technology,2016,292:46-53.
[2] 刁雄,李双跃,黄鹏.进料方式对超细分级机分级性能的影响[J].化工学报,2012,63(12):3818-3825.DIAO X,LI S Y,HUANG P.Effect of feeding type on classification performance of superfine classifier[J].CIESC Journal,2012,63(12):3818-3825.
[3] HUANG Q,LIU J X,YU Y.Turbo air classifier guide vane improvement and inner flow field numerical simulation[J].Powder Technology,2012,226:10-15.
[4] SHAPIRO M,GALPERIN V.Air classification of solid particles:a review[J].Chemical Engineering and Processing,2005,44(2):279-285.
[5] MORIMOTO H,SHAKOUCHI T.Classification of ultrafine powder by a new pneumatic type classifier[J].Powder Technology,2003,131:71-79.
[6] LIU R,LIU J,YU Y.Effects of axial inclined guide vanes on a turbo air classifier[J].Powder Technology,2015,280:1-9.
[7] 高利苹,于源,刘家祥.涡流空气分级机转笼转速对其分级精度的影响[J].化工学报,2012,63(4):1056-1062.GAO L P,YU Y,LIU J X.Effect of rotor cage rotary speed on classification accuracy in turbo air classifier [J].CIESC Journal,2012,63(4):1056-1062.
[8] GAO L P,YU Y ,LIU J X.Study on the cut size of a turbo air classifier[J].Powder Technology,2013,237:520-528.
[9] 刁雄,李双跃,李良超,等.超细分级机进料管内颗粒浓度分布特性的数值模拟[J].过程工程学报,2011,11(5):729-735.DIAO X,LI S Y,LI L C,et al.Numerical simulation of particle concentration distribution characteristics in feed tube of super-segmentation machine[J].The Chinese Journal of Process Engineering,2011,11(5):729-735.
[10] ALTUN O,TOPRAK A,BENZER H,et al.Multi component modelling of an air classifier [J].Minerals Engineering,2016,93:50-56.
[11] ALTUN O,BENZER H.Selection and mathematical modelling of high efficiency air classifiers[J].Powder Technology,2014,264:1-8.
[12] BENZER H,ERGUN L,LYNCH A J,et al.Modelling cement grinding circuits[J].Minerals Engineering,2001,14 (11):1469-1482.
[13] ESWARAIAH C,ANGADI S I,MISHRA B K.Mechanism of particle separation and analysis of fish-hook phenomenon in a circulating air classifier [J].Powder Technology,2012,218:57-63.
[14] XING W J,WANG Y Z,ZHANG Y,et al.Experimental study on velocity field between two adjacent blades and gas-solid separation of a turbo air classifier[J].Powder Technology,2015,286:240-245.
[15] 曾川,刘传慧,陈海焱,等.二次风量对 LNJ-36A 型气流分级机分级性能的影响[J].化工进展,2015,34(11):3859-3863.ZENG C,LIU C H,CHEN H Y,et al.Effects of secondary air on the classification performances of LNJ-36A air classifier[J].Chemical Industry and Engineering Progress,2015,34(11):3859-3863.
[16] 张胜林,谌永祥,李双跃.涡流空气分级机工艺参数对窄级别产品粒径分布和产率的影响[J].化工进展,2015,33(5):1113-1117.ZHANG S L,CHEN Y X,LI S Y.Effects of process parameters on particle size distribution and productivity of narrow level product in turbo air classifier [J].Chemical Industry and Engineering Progress,2015,33(5):1113-1117.
[17] 安连锁,吕玉坤.泵与风机[M].北京:中国电力出版社,2008.AN L S,Lü Y K.Pumps and fans [M].Beijing:China Electric Power Press,2008.
[2] 刁雄,李双跃,黄鹏.进料方式对超细分级机分级性能的影响[J].化工学报,2012,63(12):3818-3825.DIAO X,LI S Y,HUANG P.Effect of feeding type on classification performance of superfine classifier[J].CIESC Journal,2012,63(12):3818-3825.
[3] HUANG Q,LIU J X,YU Y.Turbo air classifier guide vane improvement and inner flow field numerical simulation[J].Powder Technology,2012,226:10-15.
[4] SHAPIRO M,GALPERIN V.Air classification of solid particles:a review[J].Chemical Engineering and Processing,2005,44(2):279-285.
[5] MORIMOTO H,SHAKOUCHI T.Classification of ultrafine powder by a new pneumatic type classifier[J].Powder Technology,2003,131:71-79.
[6] LIU R,LIU J,YU Y.Effects of axial inclined guide vanes on a turbo air classifier[J].Powder Technology,2015,280:1-9.
[7] 高利苹,于源,刘家祥.涡流空气分级机转笼转速对其分级精度的影响[J].化工学报,2012,63(4):1056-1062.GAO L P,YU Y,LIU J X.Effect of rotor cage rotary speed on classification accuracy in turbo air classifier [J].CIESC Journal,2012,63(4):1056-1062.
[8] GAO L P,YU Y ,LIU J X.Study on the cut size of a turbo air classifier[J].Powder Technology,2013,237:520-528.
[9] 刁雄,李双跃,李良超,等.超细分级机进料管内颗粒浓度分布特性的数值模拟[J].过程工程学报,2011,11(5):729-735.DIAO X,LI S Y,LI L C,et al.Numerical simulation of particle concentration distribution characteristics in feed tube of super-segmentation machine[J].The Chinese Journal of Process Engineering,2011,11(5):729-735.
[10] ALTUN O,TOPRAK A,BENZER H,et al.Multi component modelling of an air classifier [J].Minerals Engineering,2016,93:50-56.
[11] ALTUN O,BENZER H.Selection and mathematical modelling of high efficiency air classifiers[J].Powder Technology,2014,264:1-8.
[12] BENZER H,ERGUN L,LYNCH A J,et al.Modelling cement grinding circuits[J].Minerals Engineering,2001,14 (11):1469-1482.
[13] ESWARAIAH C,ANGADI S I,MISHRA B K.Mechanism of particle separation and analysis of fish-hook phenomenon in a circulating air classifier [J].Powder Technology,2012,218:57-63.
[14] XING W J,WANG Y Z,ZHANG Y,et al.Experimental study on velocity field between two adjacent blades and gas-solid separation of a turbo air classifier[J].Powder Technology,2015,286:240-245.
[15] 曾川,刘传慧,陈海焱,等.二次风量对 LNJ-36A 型气流分级机分级性能的影响[J].化工进展,2015,34(11):3859-3863.ZENG C,LIU C H,CHEN H Y,et al.Effects of secondary air on the classification performances of LNJ-36A air classifier[J].Chemical Industry and Engineering Progress,2015,34(11):3859-3863.
[16] 张胜林,谌永祥,李双跃.涡流空气分级机工艺参数对窄级别产品粒径分布和产率的影响[J].化工进展,2015,33(5):1113-1117.ZHANG S L,CHEN Y X,LI S Y.Effects of process parameters on particle size distribution and productivity of narrow level product in turbo air classifier [J].Chemical Industry and Engineering Progress,2015,33(5):1113-1117.
[17] 安连锁,吕玉坤.泵与风机[M].北京:中国电力出版社,2008.AN L S,Lü Y K.Pumps and fans [M].Beijing:China Electric Power Press,2008.