摘要
碟式离心机作为高效分离机械广泛应用于食品、化工、制药等行业生产.为探究碟式离心机的内部流场及分离效率,进行了现场试验,并根据Σ理论建立了具有20层碟片的简化三维物理模型,利用FLUENT软件对转鼓内的流场及分离过程进行数值模拟.试验结果表明,转速和进料量对碟式离心机分离效率影响较大,提高转速、降低进料量均能提高离心机的分离效率,通过分析进出口物料的粒径发现,在试验工况下,粒径大于6μm的颗粒均能被有效分离,改变操作参数主要影响粒径为2~5μm的颗粒的分离.模拟结果表明:在碟片间隙内,物料对碟片的跟随性良好,压力与半径呈现出二次型正比关系,周向速度与半径成正比关系,在沉渣区域物料明显滞后于转鼓转动,这导致离心液压和周向速度均小于理论值,同时随着转速的提高,沉渣区域物料的滞后性更加明显;由于上升通道存在,在碟片间隙内局部位置存在明显轴向速度,从而对碟片内的流动产生干扰,导致碟片大端位置的周向速度和离心液压分布不均;在两相分离过程中,颗粒自液相中分离,沉积于上碟片的下表面,并滑落至转鼓沉渣区,固相颗粒在碟片间隙内主要堆积于定距条前侧,在相邻两个定距条之间,固相体积分数沿顺时针方向减少.研究方法与结果为碟式离心机分离性能模拟计算提供了参考,对碟式离心机的设计与结构优化提供了数据指导.
Disk stack centrifuges(DSC)are widely used in food,chemical,pharmaceutical,and other industries as efficient separation machines.Field experiments were performed to explore the internal flow field and separation law of DSC,and a simplified three-dimensional physical model with 20 disks was established based on Σ theory.The flow field and separation process in the drum were numerically simulated using FLUENT.The experimental results show that the rotational speed and feed rate have a considerable influence on the separation efficiency of the disk stack centrifuge.Increasing the rotational speed and decreasing the feed rate can improve the separation efficiency of DSC.By analyzing the particle size of inlet and outlet materials,it has been found that under the experimental conditions,particles larger than 6μm can be effectively separated,whereas changing the operating parameters primarily affects the separation of particles with a particle size of 2-5μm.Within the disk gap,simulation results show that the relationship between pressure and radius is quadratically proportional.The radius is proportional to the tangential velocity.In the area of sediment,materials obviously lag behind the rotation of the drum,resulting in lower centrifugal hydraulic and tangential velocity than the theoretical values.Moreover,as the rotational speed increases,the hysteresis of materials made of sedimentary materials becomes more apparent.Due to the presence of rising channels,there is an obvious axial velocity at local positions in the disk gap,which interferes with the flow in the disk,resulting in an uneven distribution of tangential velocity and centrifugal hydraulic pressure at the large end of the disk.In the two-phase separation process,particles are separated from the liquid phase,settled on the lower surface of the upper disk,and then slid to the sediment area of the drum.The solid particles primarily accumulate in front of the spacer bar in the gap of the disk,and the solid volume fraction decreases clockwise between two adjacent spacer bars.The study method and results provide a reference for the simulation calculation of DSC separation performance and provide data guidance for the design and structural optimization of dish-type centrifuges.
作者
朱国瑞
郝泽基
吴将天
Pinto Lopes Maia Junior Joaquim
谭蔚
Zhu Guorui;Hao Zeji;Wu Jiangtian;Pinto Lopes Maia Junior Joaquim;Tan Wei(School of Chemical Engineering and Technology,Tianjin University,Tianjin 300350,China;Zhejiang Institute of Tianjin University,Ningbo 315201,China;Zhejiang Qingji Industry Co.,Ltd.,Hangzhou 311401,China)
出处
《天津大学学报（自然科学与工程技术版）》
EI
CAS
CSCD
北大核心
2023年第6期579-587,共9页
Journal of Tianjin University：Science and Technology
基金
国家自然科学基金资助项目(22078236).
关键词
碟式离心机
离心沉降
数值模拟
固液两相分离
disk stack centrifuge(DSC)
centrifugal sedimentation
numerical simulation
solid-liquid two-phase separation
作者简介
朱国瑞(1987-),女,博士,副教授,zhuguorui@tju.edu.cn;通信作者:谭蔚,wtan@tju.edu.cn.
