沥青搅拌设备多层振动筛分效率计算及影响规律研究
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摘要
针对以往沥青搅拌设备振动筛分效率计算未考虑细粒度与粗粒度物料混杂的情况,提出基于离散单元法的颗粒动力学分析获得不同粒度物料的占比,进一步结合格氏法与总效率公式建立沥青搅拌设备多层直线振动筛的筛分效率计算方法。首先建立多层直线振动筛以及物料颗粒的三维模型,基于离散单元法进行颗粒动力学分析,获得筛上物与筛下物中不同粒度颗粒的分布情况。然后建立筛分产品产率问题的优化函数,代入颗粒分布计算结果,通过线性规划方法计算产品产率以及各层物料中不同粒度颗粒的占比,最后根据总效率公式计算多层振动筛各层的筛分效率。现场试验验证了筛分效率计算方法的有效性。进一步研究振动参数的影响可以知道,当振动频率控制在18 Hz~20 Hz之间,振动方向角在70o~80o,筛面倾角位于11o~16o之间,振动筛筛分效率能够处于较合理控制范围。
Proportions of materials through screen are usually adopted to estimate screen efficiency when the designs of asphalt mixing equipment are appraised. In order to consider the size of mixed particles and gain the proportions of different materials and the screening efficiency, a computation method based on the discrete element method is proposed. In this method, the total efficiency formula and the K. Grumbrecht method are applied. Firstly, the 3 D models of a multi-layer linear vibration screen and material particles are established respectively by commercial software. The particle dynamic analysis is implemented by means of the discrete element method and different solid particle distributions in screen residue and screen underflow are obtained. Then, the optimization function is established for analyzing the screening productivity.The proportions of materials with different sizes of particles are computed by the linear programming approach. Finally, the screening efficiency of each screen layer can be obtained by the total efficiency formula. The validity and practicability of this method are confirmed by the in-situ test. Moreover, the influence of some vibration parameters, such as vibration frequency, angle of screen, amplitude and direction angle of vibration, on screening efficiency is discussed. It is found that to obtain higher screening efficiency, the vibration frequency, the direction angle of vibration and the inclination angle of the screen should be within 18 Hz-22 Hz, 70 o-80 o, 11 o-16 o, respectively.
Proportions of materials through screen are usually adopted to estimate screen efficiency when the designs of asphalt mixing equipment are appraised. In order to consider the size of mixed particles and gain the proportions of different materials and the screening efficiency, a computation method based on the discrete element method is proposed. In this method, the total efficiency formula and the K. Grumbrecht method are applied. Firstly, the 3 D models of a multi-layer linear vibration screen and material particles are established respectively by commercial software. The particle dynamic analysis is implemented by means of the discrete element method and different solid particle distributions in screen residue and screen underflow are obtained. Then, the optimization function is established for analyzing the screening productivity.The proportions of materials with different sizes of particles are computed by the linear programming approach. Finally, the screening efficiency of each screen layer can be obtained by the total efficiency formula. The validity and practicability of this method are confirmed by the in-situ test. Moreover, the influence of some vibration parameters, such as vibration frequency, angle of screen, amplitude and direction angle of vibration, on screening efficiency is discussed. It is found that to obtain higher screening efficiency, the vibration frequency, the direction angle of vibration and the inclination angle of the screen should be within 18 Hz-22 Hz, 70 o-80 o, 11 o-16 o, respectively.
引文
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[2]CLEARY P W.Industrial particle flow modelling using discrete element method[J].Engineering Computation,2009,26(6):698-743
[3]J W FERNANDEZ,P W CLEARY,M D SINNOTT,et al.Using SPH one-way coupled to DEM to model wet industrial banana screens[J].Minerals Engineering,2011,24(8):741-753.
[4]PAUL W CLEARY.Prediction of coupled particle and fluid flows using DEM and SPH[J].Minerals Engineering,2015,73(15):85-99.
[5]焦红光,赵跃民.用颗粒离散元法模拟筛分过程[J].中国矿业大学学报,2007,36(2):232-236.
[6]LALA ZHAO,YUEMIN ZHAO,CHUNYONG BAO,et al.Optimisation of a circularly vibrating screen based on DEM simulation and Taguchi orthogonal experimental design[J].Powder Technology,2017,310:307-317.
[7]鲍春永.基于DEM的振动筛分过程机理研究[D].徐州:中国矿业大学文,2016.
[8]CHEN Y H,TONG X.Application of the DEM to screening process:a 3D simulation[J].Mining Science and Technology,2009,19(4):493-497.
[9]WANG GUIFENG,TONG XIN.Screening efficiency and screen length of a linear vibrating screen using DEM 3D simulation[J].Mining Science and Technology(China),2011,21:451-455.
[10]KENNETH C.WILLIAMS,WEI CHEN,SEBASTIAN WEEGER,et al.Particle shape characterization and its application to discrete element modeling[J].Particuology,2014,12:80-89.
[11]贺朝霞.沥青搅拌设备振动筛系统动态特性及参数影响研究[R].镇江:博士后出站报告,2015.
[12]杨龙飞.基于DEM的沥青混合料振动筛分效率估算与试验研究[D].西安,长安大学,2015.
[13]王桂锋,童昕,陈艳华,等.基于DEM的振动筛筛分参数对筛分效率影响的研究[J].矿山机械,2010,38(15):102-106.
[14]闻邦椿,刘树英,何勍.振动机械的理论与动态设计方法[M].北京:机械工业出版社,2000.