结构参数对双溢流旋流器内空气柱性能的影响

传统旋流器一次分级只能得到溢流和底流两种产品,造成产品粒级范围太过宽泛,达不到精细分级的要求。本文提出了一种具有双溢流管结构的多产品旋流器,建立了流场模型,利用流体力学多相流理论,对旋流器内部流场进行了数值模拟,得到了内外双溢流流场分布特点,获取了流场和空气柱的形成、发展演化过程。对底流口、溢流口结构参数对旋流器内空气柱性能的影响进行了仿真分析,结果表明:旋流器内空气柱直径随着底流口和溢流口直径的增大而增大,当内溢流管直径小于底流口直径时,空气柱较为紊乱。研究结果对分析空气柱影响涡旋运动及优化旋流器结构参数奠定了理论基础。     

基于高速摄像技术的旋流器空气柱特征研究

利用高速摄像技术研究了不同锥角和进口流量下旋流器内空气柱的结构特征。结果表明,旋流器内空气柱的形状、弯扭程度因旋流器锥角和进口流量不同而不同,不能单纯用柱状、麻花状、正弦曲线状等来描述。因此,为减少空气柱对旋流器分离效率的影响,旋流器应采用合适的锥角及与之相匹配的最佳进口流量。     

无压三产品重介质旋流器一段结构参数对空气柱的影响

为了研究无压三产品重介质旋流器内空气柱的形态和变化规律,利用计算流体力学软件Fluent,采用非稳态的雷诺应力模型一段旋流器结构参数和操作参数对空气柱的影响,进而分析对能耗和分选的影响。结果显示旋流器内部空气柱在21.67s时基本成型,二段旋流器先于一段旋流器形成空气柱;入料速度小于4m/s旋流器内部无法形成空气柱,超过临界速度后旋流器内部可以形成完整稳定的空气柱,过大的入料速度会使得一段旋流器内空气柱体积百分数减少,二段旋流器内空气柱体积百分数增加,一段旋流器内空气柱不贯通;一段旋流器溢流管直径为380mm,溢流管插入深度在410~610mm范围,旋流器内空气柱体积分数较低,空气柱摆动较小稳定性强。     

水力旋流器内空气柱直径的研究

探讨了不同排料方式下的水力旋流器的溢流口直径和压力降对空气柱直径的影响，分析了水封式水力旋流器底流背压、溢流背压及系统压力对空气柱直径的影响规律。可作为水力旋流器内空气柱的操作控制及改善水力旋流器工作性能的依据。     

锥体结构对水力旋流器内流场及分离性能的影响

使用FLUENT软件对不同锥体结构的水力旋流器进行了清水流场及颗粒分离性能的模拟。在相同处理能力条件下,对于单锥结构的旋流器,增大锥角,旋流器内的压力降和最大切向速度增大。相比常用于细粒分级的长锥旋流器,上部采用大锥角、下部采用小锥角的变锥角旋流器具有更高的最大切向速度和更稳定的轴向及径向流速分布。空气柱直径随着切向速度的增大而变大。对不同粒径固体颗粒相分离的模拟结果显示,变锥角旋流器的分离粒度小于同直径的长锥旋流器。     

底流口直径对筛网旋流器分级效果的影响

为提高筛网旋流器的分级效果,在对柱段筛网直径与筛孔直径、入料口、溢流管、锥角与底流口设计的基础上制造筛网旋流器样机,通过改变样机的底流口直径来研究其对分级效果的影响。试验结果表明:筛网旋流器的分级效率随底流口直径的增大而增加,分级粒度随底流口直径的增大而减小。     

重介质旋流器结构和工艺参数对空气柱的影响研究

重介质旋流器是一种使用广泛的高效选煤设备,旋流器内部空气柱的大小对旋流器分选效率及能耗影响显著。利用FLUENT研究了重介质旋流器的结构和工艺参数对空气柱的影响。结果表明,在入料速度超过临界速度后,旋流器内部形成完整的空气柱,其大小与入料速度没有关系;空气柱直径在溢流口附近最大,在溢流管插入位置最小;重介质悬浮液的黏度越大,空气柱越小,能耗越小;溢流管插入深度越大,空气柱越大,能量耗散越大。     

重介质旋流器分选过程的离散分析与数值模拟

重介质旋流器广泛应用于煤炭分选,分选过程十分复杂,试验测试研究重介质旋流器内部流场和颗粒运动特性费时费力,成本较高。随着数值计算技术的发展,国内外学者应用数值模拟方法研究旋流器内部的多相流流场。采用计算流体力学(CFD)与离散分析方法(DEM)耦合技术对重介质旋流器的分选过程进行数值模拟研究,为重介质旋流器的结构参数和操作参数的优化提供了一种新途径。用Fluent软件研究了旋流器内部悬浮液速度场、密度场、压力梯度场和黏度场,用EDEM软件研究了旋流分选过程中的煤粒运动行为及分选效果的评价。研究结果表明:悬浮液压力分布和压力梯度分布径向基本对称,溢流口和底流口处压力值最低。器壁沿径向形成了压力梯度,差值逐渐增大,空气柱边界处压力梯度最大;不同尺度的煤粒在旋流器内部的停留时间不同,相同密度的煤粒,粒度越小,停留时间越长。溢流中排出煤粒在旋流器中的停留时间明显长于从底流口排出的煤粒。溢流口排出的煤粒,密度越大,停留时间越长,底流口排出的煤粒,密度越大,停留时间越短。不同的旋流器结构参数对分选的影响程度不尽相同,其中溢流管直径的影响最为显著,溢流管直径超过500 mm时,不能形成完整的空气柱,无法分选。溢流管直径为300 mm时,分选效果较好;溢流管插入深度显著影响分选精度,插入深度为160 mm时,分选密度增大,细小高密度的煤颗粒将错配进入溢流,溢流管插入深度为320～800 mm时,分选密度接近悬浮液密度,分选指标E_p=0. 084～0. 100,分选效果较好。底流口直径对旋流器选精度影响较大,当底流口直径为272和306 mm时,分选密度与悬浮液密度接近,E_p值小于0.1,分选效果较好。圆柱段长度对于分选密度影响不明显。     

柱锥连接处扩径对水力旋流器性能的影响

研究了柱锥连接处适度扩径对水力旋流器性能的影响。在其它条件相同的条件下, 对扩径后锥角为20°和30°水力旋流器的分级效率、分级精度、处理能力、分流比和浓缩性能等进行了对比试验。试验结果表明, 相对于普通水力旋流器, 柱锥连接处适度扩径的水力旋流器分级效率总体上提高了, 但浓缩效果变差, 处理能力减小, 而且随着扩径幅度的增加而减小; 分流比随扩径幅度增大而增大。所得研究成果对选择旋流器结构参数以满足不同条件要求具有指导意义。     

DWP重介质旋流器流场的数值模拟

选用雷诺应力湍流计算模型（RSM）,对两种直径为1 300 mm的DWP型重介质旋流器的流场进行了数值模拟,并对结构参数和能耗进行了研究.对流场三维速度、压强、密度和空气柱的数值模拟研究表明,在旋流器内存在短路流现象;双入介DWP旋流器分选效果优于单入介DWP旋流器,处理能力高于单入介DWP旋流器,能耗比单入介DWP旋流器减少33%.     

Flow conditions in the air core of the hydrocyclone

The geometry and movement of the air core are sensitive indicators of the operational state of hydrocyclones. Therefore, an increased knowledge of the air core behaviour is desirable.Measurements of the air-core diameter in transparent hydrocyclones operated with a suspension of glass spheres are presented. The experiments indicate the dependencies between feed-solids content, air-core diameter, and spray angle of the underflow.Additionally, the air flow inside the air core in a transparent 50 mm water cyclone was experimentally investigated. Visualization techniques show the whirling motion of the air-core flow that is driven by the rotating liquid boundary of the air core. The radial distribution of the tangential air velocity was determined. The mean axial air velocity was shown to be dependent on the pressure drop and the hydrocyclone geometry. At the overflow discharge the air core is dispersed, and forms an aero suspension.Thus, the paper presents new aspects of the complex multi-phase flow in the hydrocyclone considering the gaseous phase.     

Study of flow behaviour in a three-product cyclone using computational fluid dynamics

Simplicity in design and minimal floor space requirements render the hydrocyclone the preferred classifier in mineral processing plants. Empirical models have been developed for design and process optimisation but due to the complexity of the flow behaviour in the hydrocyclone these do not provide information on the internal separation mechanisms. To study the interaction of design variables, the flow behaviour needs to be considered, especially when modelling the new three-product cyclone.Computational fluid dynamics (CFD) was used to model the three-product cyclone, in particular the influence of the dual vortex finder arrangement on flow behaviour. From experimental work performed on the UG2 platinum ore, significant differences in the classification performance of the three-product cyclone were noticed with variations in the inner vortex finder length. Because of this simulations were performed for a range of inner vortex finder lengths. Simulations were also conducted on a conventional hydrocyclone of the same size to enable a direct comparison of the flow behaviour between the two cyclone designs. Significantly, high velocities were observed for the three-product cyclone with an inner vortex finder extended deep into the conical section of the cyclone. CFD studies revealed that in the three-product cyclone, a cylindrical shaped air-core is observed similar to conventional hydrocyclones. A constant diameter air-core was observed throughout the inner vortex finder length, while no air-core was present in the annulus.     

给矿浓度和入口压力对水力旋流器分级效率的影响

通过对水力旋流器内流动的固体颗粒运动的理论分析与试验测试,以及对水力旋流器入口压力考察,探讨了给矿浓度和入口压力对水力旋流器分级的影响。试验给出了不同给矿浓度和压力下的颗粒分级效率曲线。并结合目前选矿厂应用的实际及未来发展趋势作了详细的研究。     

New understanding of a hydrocyclone flow field and separation mechanism from computational fluid dynamics

The flow field of a 2 in. hydrocyclone is shown to be significantly asymmetric without precession, through both computational fluid dynamics (CFD) and experimental observation. Hence the application of full three-dimensional modelling is demonstrated to be essential. Further, CFD predicts that the axial pressure is not below atmospheric prior to development of the air core and that such development is not pressure driven. In fact, initial insight into a cause of instability of the air-core is identified from the CFD and supported through experimental observation. The predictions use the second-order differential-stress turbulence model which has previously been identified to represent a minimum model. Lastly, the inclusion of full three-dimensional modelling and high-order turbulence modelling leads to a new understanding of particle-separation classification within the hydrocyclone, including a significant stochastic component.     

Experimental study of flow patterns in deoiling hydrocyclone

Using a two-component laser Doppler velocimeter, the axial velocity, tangential velocity and fluctuation velocity were measured in a 35-mm deoiling hydrocyclone. Air core occurs in the hydrocyclone when inlet flow rate is more than 2.00 m³/h. The fluctuation velocities with air core are greater than without air core. The velocity magnitudes are dependent on the inlet flow rate and the flow character is not change by changes in the inlet flow rate in hydrocyclone. The velocity fluctuations are greater near the core and near the wall. The results show that air core in the hydrocyclone will arose turbulence fluctuation. These studies are helpful to understand the separation mechanism of deoiling hydrocyclone.     

脱硫用水力旋流器进口压力与浓度对其性能影响的研究

本实验研究了水力旋流器的进口压力与浓度对旋流器性能的影响,包括生产能力、分级效率、分级精度、分级粒度等指标。对于不同的浓度和进口压力对旋流器性能的影响做了定性的分析,研究其变化规律有助于水利旋流器的进一步优化和改进。     

旋流器中最佳操作参数的研究

通过对液滴在旋流场中所受剪切应力的分析,并综合操作参数与旋流器结构尺寸及进料物性的关系,推导出最佳进料平均速度和最佳进料流量的计算公式。采用水与煤油的混合物作为进料进行试验,将理论计算值与试验结果进行比较,证明了计算公式的可靠性和准确性。     

基于人工神经网络的水力旋流器选型及优化

为了实现对水力旋流器的全面设计,建立了3层BP神经网络模型,该模型可根据分离粒度、生产能力、底流质量浓度等值,选择合适的水力旋流器。经10组数据测试,选型误差为:底流口直径10.43%,溢流口直径7.51%,插入深度17.86%,入料压力20.24%,选型精度高于传统方法。该模型既可用于设备选型,也可用于优化旋流器参数。选择合适的水力旋流器分级加重质,制备得到的粗、细两产品分别满足湿法、干法对加重质要求,对我国选煤业发展有重大意义。     

齐大山铁矿粗细分级旋流器数值优化试验研究

为提高齐大山铁矿选矿厂[?]660 mm粗细分级水力旋流器的沉砂产率,从而增大后续重选作业的给矿量,基于数值模拟方法系统考察了水力旋流器结构参数对水力旋流器分离性能的影响。结果表明：增大沉砂口直径和柱段高度可以有效提高各粒级在沉砂中的分配率,而增加溢流管直径和小锥锥角则相反。基于数值试验结果进行了粗细分级水力旋流器工业试验,与原旋流器相比,优化后的旋流器沉砂产率提高了7.67个百分点,在保证分级效率的前提下可以有效提高沉砂产率。优化后的水力旋流器可以有效增加重选作业给矿量,并为同类型矿山的水力旋流器结构设计提供参考。