分级轮转速对粒径分布的影响

通过计算流体力学软件Fluent对FTW-350型涡轮空气分级机内部的分级流场进行数值模拟,根据模拟结果对不同分级轮转速时分级机内部流场的动态压力、湍动能和流动速度的分布特性进行对比分析;通过实验研究涡轮空气分级机中分级轮转速对粒径分布的影响,在每种分级轮转速时进行3种不同的加料速度实验,对激光粒度仪测得的分级产物的累积粒径、平均粒径、累积体积分布和粒径频率分布进行对比分析。结果表明:转速增加有利于分级流场的稳定,并且在转速较小时,增大分级轮转速有利于改善分级产物的粒径分布;分级轮转速变化对粒径分布的影响随着加料速度的增大不断减小。     

气流分级机流场的数值模拟与优化

运用计算流体力学数值模拟的方法,研究气流分级机的内部气流流场情况,并对于分级机的工作参数进行优化。通过采用滑移网格技术模拟分级轮在气流分级机内的旋转,用结构网格与非结构网格结合的方法对气流分级机进行网格划分,主要研究了分级轮不同叶片数(4、6、12片),不同转速(500、1000、2000、3000r/min)下分级机内部流场情况并给出了相关解释。通过对不同参数的比较给出了优化的参数。模拟结果表明,分级轮转速越高、叶片数越多,分级效果越好。     

立式涡轮分级机分级性能研究

为了研究立式涡轮分级机外筒体倾斜角度对分级效率的影响,经过分析分级机的气流流场、分级性能及存在的问题,采用自制CP-20型气流粉碎机在不同外筒体倾斜角度的情况下对河砂进行粉碎和分级实验,以获得最佳外筒体倾斜角度。结果表明:对于河砂而言,外筒体倾斜角度为0~15°时,随着角度的增大,分级效率先增大后减小;最佳外筒体倾斜角度为9°。     

离心式气流分级机的现状与进展

从分级流场构建的角度对离心式气流分级机进行梳理分类,按照分级区旋涡转轴的不同分为竖直旋涡分级机和水平旋涡分级机,并对几种代表机型的流场特征及研究进展进行了剖析,指出竖直旋涡分级机的研究较多,而水平旋涡分级机的研究相对较少,强调了合理构建与组合分级流场和淘洗流场的重要性,展望了离心式气流分级机的研究前景。     

东莞市五全机械有限公司

正产品名称:VSFJ涡轮气流分级机产品简介:VSFJ系列涡轮气流分级机,是东莞市五全机械有限公司为了解决国内普通分级机分级效果差、产量低等问题。借鉴德国阿尔派、阿肯图,结合自己生产配套VSLM系列超细立磨分级技术,开发出来一款行业内领先、可试用各种类型研磨设备分级机。可分选1.5~30um、2um含量最高可达90%的涡轮气流分级机。     

供应信息

绵阳高新区巨子超微科技有限公司 原理简介：压缩空气由流化床四周相对的超音速喷管加速后进入流化床,在流化床粉碎机内相互撞击形成粉碎腔。物料由加料口进入流化床粉碎机内,在气流的带动下,物料于粉碎腔中部相互碰撞、摩擦而粉碎。合格的细粉由上升气流携带进入流化床上部的涡轮分级机,分级机对合格的物料进行分级后进入旋风收集器（如需要几个粒径段的产品,则加设多台立式涡轮分级机）。更细的尾料部分则由气流携带进入布袋除尘器,经布袋过滤后,尾料进入除尘器下部的出料口,纯净的空气排空。     

涡轮式气流分级机分级精度影响因素分析

气流分级机分级粒径的不稳定是造成精度下降的根本原因。本文对不均匀气流速度场导致分级粒径沿涡轮轴向的空间波动，湍流脉动导致分级粒径的时间波动，范德华引力产生的假大颗粒导致鱼钩效应而影响细粉的分级以及与一次风、二次风均不发生作用的物料直接进入粗粉，相当于分级粒径为０，而使分级精度明显下降等因素进行了分析，推导出的各影响因素作用的数学方程可用于定性分析。     

涡轮式气流分级机分级精度影响因素分析

气流分级机机分级粒径的不稳定是造成精度下降的根本原因，本文对不均匀气流速度场导致分级粒径沿涡轮轴和的空间波动，湍流脉动导致分级粒径的时间波动，范德华引力产生的假大颗粒导致鱼钩效应而影响细粉的分级以及一次风，二次风均不发生作用的物料直接进入粗粉，相当于分级粒径为０，而使分级精度明显下降等因素进行了分析，推导出的各影响因素作用的数学方程可用于定性分析。     

FJW涡轮分级机的分级机理研究

为了研究涡轮分级机的分级机理对于合理设计分级腔的结构、优化系统操作参数的影响,介绍了一种高效精密分级设备——150FJW型卧式涡轮分级机的结构和工作参数,分析了其分级机理,根据实验探讨了影响其性能的关键因素。研究表明:①颗粒的浓度对分级精度有较大的影响;②分级粒径的大小与涡轮转速、抽风机风量、风压及涡轮结构参数有关;③分析分级精度时要考虑分级机内部紊流的影响。     

强制涡超细分级机内腔气-固两相湍流流场数值模拟

建立了FW-Φ150型强制涡卧式涡轮分级机内腔叶片之间气-固两相流的双流体理论模型熏并利用通用的流体力学计算软件进行了数值模拟。结果表明:该涡轮分级机在正常工作状态时,内腔流场遵循强湍流流动规律;粒子群的运动规律是,粒子的粒径越大,越易向叶片外边缘聚集,直至返回分级区;随着转速的增大,流场的涡流现象越来越强,相同粒径的粒子,当转速增大到一定的程度时,出现了反流现象,使已经分离出的细粒又返回到分级区,而影响分级机的分级效率。     

Effect of the rotor cage chassis on inner flow field of a turbo air classifier

As the connection between the center of rotor cage and the coarse powder collecting cone, rotor cage chassis of the turbo air classifier directly influences airflow movement in the classifier. In order to study the effect of rotor cage chassis on the inner flow field of a turbo air classifier, the flow fields of four rotor cage chassis structures with different opening size are simulated and compared using ANSYS-FLUENT 17.0. The simulation results show that there is “bypass flow” phenomenon for the classifier with the open rotor cage chassis, compared with the closed rotor cage chassis. The “bypass flow” phenomenon can change the airflow velocity distribution of the annular region. For the open rotor cage chassis, its opening size has no significant effect on the flow field distribution and the airflow velocity. However, the open or closed rotor cage chassis has great effect on the flow field distribution and the airflow velocity. The calcium carbonate classification comparative experiments are carried using the open and closed rotor cage chassis structures. The experiment results show that the open rotor cage chassis can decrease the cut size, and the closed rotor cage chassis can improve the classification accuracy.     

Effect of rotor cage's outer and inner radii on the inner flow field of the turbo air classifier

The effects of rotor cage's outer and inner radii on flow field of the turbo air classifier are comparatively analyzed by numerical simulation using ANSYS-FLUENT. The results of quantitative analysis show when the rotor cage's outer and inner radii are increased, the tangential velocity, radial velocity and upward axial velocity decrease in the annular region and near the entrance of the rotor cage. However, when the rotor cage's outer and inner radii are too large or too small, the tangential velocity and radial velocity will be fluctuated greatly. Moreover, the rotor cage's outer and inner radii directly influence the radial velocity distribution in the rotor cage channel. The rotor cage's outer and inner radii should not be too large or too small. Therefore, in the seven contrast rotor cage models, model 100–70 and 90–60 are selected to carry out the calcium carbonate classification experiments due to their small tangential velocity and radial velocity fluctuations and well-distribution in the rotor cage channel. The experimental results reflect the characteristics of the numerically simulated flow field in the classifier.     

CFD simulation and performance optimization of a new horizontal turbo air classifier

A new horizontal turbo air classifier equipped with two inclined air inlets has been introduced. The flow field and classification performance of the classifier have been investigated using CFD method and response surface methodology (RSM). Simulation results show that the flow field is composed of the primary swirling flow and the secondary upward washing air, and the uniformly distributed swirling flow occupies the classifying chamber. The tangential gas velocity reaches the maximum value on the outer surface of the rotor cage, generating strong centrifugal force for the particle classification. The discrete phase model (DPM) can predict the cut sizes, but cannot present the fish-hook phenomenon. The desirable experimental condition by targeting the cut size of 20 μm and minimizing the classifying accuracy index is, rotor speed of 1373.6 rpm, primary air volume flow rate of 261.8 m³/h and secondary air volume flow rate of 42.4 m³/h. The corresponding fine and coarse fraction loss are less than 1.42% and 7.24%, respectively. This study provides a new strategy to design the horizontal turbo air classifier.     

CFD simulation and optimization of the flow field in horizontal turbo air classifiers

This paper mainly presents a numerical study of the gas flow in horizontal turbo air classifiers. The effect of the air-inlet direction on the performance of classifier was also investigated through powder classification experiments. The simulated results show that the vertical vortex is the dominant flow in conical part of the classifier and there exists the horizontal vortex in the classifying chamber. The tangential velocity profile resembles a Rankine vortex inside the rotor cage. The vertical vortex intensity increases with increasing the inlet air velocity, while the rotor cage speed has limited effect on the control of gas pathlines in the classifying chamber. Horizontal turbo air classifiers are divided into four quadrants according to the air-inlet direction. For classifiers in quadrants I and III, a double-layer flow with opposite directions generates around the rotor cage which causes a secondary vortex. The secondary vortex is eliminated and the airflow becomes uniform in the classifier that belongs to quadrant Π or IV. The experimental results with fluidized catalytic cracking catalysts and fly ash demonstrate that cut sizes of this classifier decrease averagely by 5 μm and 2.2 μm respectively, and the classification accuracy increases by 7.5–10.3%.     

梯级送风对冷藏车厢内温度场的影响分析

合理的厢内温度场是保证冷藏车运输货物品质、节能降耗的关键因素之一。为提高厢内温度场的均匀性,本文提出了单温区冷藏车的梯级送风模式。无梯级送风时,冷风在车厢内形成整体环流,流动方向较为集中,不利于整体降温;有梯级送风时,车厢顶部增加了风机,冷风速度得以提高,且流动方向更加分散,有利于提高整体降温速度和温度场均匀性。建立了冷藏车厢的仿真模型,利用CFD研究梯级送风对空仓时冷藏车厢内温度场的影响,并进行了实验验证。以射流区平均温度、车厢内整体平均温度、温度场不均匀系数和温度极差作为评价指标,对实验中采集到的温度数据进行对比分析。结果表明：梯级送风模式能够有效降低冷藏车厢内的射流区平均温度、整体平均温度、温度场不均匀系数,减小温度极差,提高降温速度;在射流区,梯级送风的影响最为显著,该处的降温幅度和降温速度都有明显优化;在车厢尾部近地面的拐角处,梯级送风的降温效果虽不明显,但降温速度明显加快。     

中大型空气源热泵空气流场特性研究

针对中大型空气源热泵冷热水机组的风侧Ⅴ型翅片管式换热器,采用CFD方法研究了其空气流场特性,采用实验测量值验证数值模拟结果,验证结果表明数值模拟的合理性和可靠性.系统分析了Ⅴ型翅片管式换热器空气流场特性,详细研究了换热器夹角大小对空气流场分布的影响并阐明了各种流动现象的产生机理.研究结果表明:Ⅴ型翅片管式换热器迎面风速沿换热器高度方向分布较不均匀,沿换热器长度方向分布相对均匀;换热器夹角大小是决定Ⅴ型换热器迎面风速分布不均匀的主要因素,主要表现在迎面风速最大值随换热器夹角值的增大而向换热器下部移动,且当换热器夹角大小为90度时,迎面风速最大值位于换热器中部位置,且此时换热器迎面风速分布呈上下对称状态.     

立磨选粉机操作参数对分级流场影响的数值模拟

采用离散相流体模型和RNG k-ε湍流模型,对涡轮式立磨选粉机内的气-固两相流场进行数值模拟,对比分析不同操作参数下的速度场、压力场和设备分级效率,获得转笼转速和系统风量对选粉机分级流场的影响规律,并进行相关的试验研究。结果表明,较低的转笼转速和过大的系统风量均会引起叶片间退行面处正漩涡的产生;转笼转速过高或系统风量较小时,分级叶片间的进入面处会出现反漩涡。正、反漩涡的产生均加剧了分级叶片间的速度波动,严重影响了分级流场的稳定性,同时也导致选粉机循环负荷的增加。综合数值模拟与试验分析,系统风量为5 500 m3/min与转笼转速为55 r/min是SMG5500型立磨选粉机的最佳参数匹配。     

Structure optimization of rotor cage blades for turbo air classifier based on entropy production analysis

Entropy production theory based on the second law of thermodynamics was introduced for evaluating the flow field inside the turbo air classifier. The three new types of rotor cage with the wedge blades, the inverted wedge blades and the spindle blades were designed, and the flow field and the classification performance of the classifiers were investigated. The results show that, compared to the rectangular blades, the productions of total entropy, turbulent entropy and wall entropy of the wedge blades are reduced by 17.3%, 25.86% and 3.34%, respectively. The corresponding effective airflow area increases by 7.5%, and the residence time of 5 μm particle is shorten by 16%. The classifier with the wedge blades has smaller cut size and higher classifying sharpness. The results validate that the turbulent entropy generation can be an indicator for monitoring the overall flow field and the classifiers’ performance.     

基于CFD技术的立式水力碎浆机内流特性分析

目的 对立式水力碎浆机内部流场特性进行分析，为改善碎浆效果和改进碎浆机的设计生产提供一定的理论依据。方法 利用Ansys Fluent软件对水力碎浆机内部流场进行数值模拟分析，采用控制变量法研究叶片数量、转子离底间隙、扰流板数量对流场特性的影响，流场的评价指标有速度场、压力场、转子功耗等。结果 数值模拟分析结果表明，立式水力碎浆机内部流体流动为典型的轴向流动模式，叶片数量、转子离底间隙及扰流板数量对流场静压和转子功耗影响较大，对流场速度影响相对较小;当转子叶片数量为2、转子离底间隙为10 mm、扰流板数量为3时，碎浆机结构的功耗相较于原始结构的功耗降低了8.5%;内部流体流动速度也大于原始结构，碎浆效率有所提高。结论 获得了水力碎浆机的内流特性，为水力碎浆机升级改进提供了参考，从而助力纸模包装行业的发展。