空间模式下初始气固速度比影响管内固粒加速特性的研究

推导出了不同初始速度的固粒群空间模式的运动解析关系并求解,通过对解析关系 的分析,研究了影响固粒加速特性的因素.给出了初始气固速度比对固粒加速输送速度影响的若干 结论,其结果对工程应用有指导意义。     

初始固相浓度变化对渣浆泵内部流动及磨损的影响

采用Euler多相流模型和标准k-ε模型,并利用SIMPLEC算法,对不同初始固相浓度下的渣浆泵内部流动进行了数值模拟,得到了叶轮和蜗壳内的压力分布、速度分布、固相浓度分布等泵内流场情况,并对渣浆泵的磨损情况作出了分析。     

液固流化床内颗粒沉降特性试验研究

以小于1.5 cm的粗煤泥颗粒为研究对象,根据密度级和粒度级的不同,将粗煤泥分成20种窄密度级和窄粒度级的均质颗粒,在 100 mm液固流化床粗煤泥分选机内,分别进行自由沉降试验和干扰沉降试验,干扰沉降包括干扰沉降速度的试验和悬浮体密度的测量。结果表明,分选机内的流态应属于过渡区域,阿连公式是粗煤泥颗粒自由沉降末速的合适公式;影响干扰沉降速度的主导因素是介质中固体颗粒数量的多少和粒群的结构特点,固体容积浓度λ越大,颗粒的干扰沉降速度降低系数β越小;机体内从底部到顶部,流化床中悬浮体的密度逐渐减小,但在接近悬浮体顶部,悬浮体的密度稍有增加;随着密度和粒度的增加,悬浮体密度自下而上减小的程度增大。     

煤仓清堵空气炮喷爆关键参数数值模拟

为了确定煤仓清堵过程中空气炮最佳初始压力,建立了空气炮喷爆数学模型,针对不同工况确定了相应的边界条件和初始条件;采用Fluent软件对初始压力0.4~0.8 MPa下的喷爆过程进行数值模拟,得到了空气炮开启后不同时刻压力、速度云图及变化曲线。分析结果表明:在系统承压范围内,初始压力越高,空气炮的冲击力越大,清堵效果越明显。当工作压力为0.8MPa时,清堵效果最好。     

水力旋流器内固相颗粒径向运动规律的预测模型

利用新型激光测量仪器——粒子动态分析仪对水力旋流器中固粒的径向运动规律实测研究的结果,得出了固相颗粒径向速度沿径向分布的数学模型,在综合考虑水力旋流器结构参数、操作参数及进料物性参数等重要影响因素后得出固相颗粒径向运动规律的准数方程。本研究所得的模型为预测固相颗粒在水力旋流器中的径向运动规律提供了依据,并为水力旋流器的分离机理及其应用的深入研究提供了理论基础。     

固相初始浓度对返排压裂液用射流泵性能影响规律

针对射流泵用于压裂液返排时效率过低的问题,采用Fluent 16.0中mixture多相流模型,对排砂射流泵开展了数值模拟研究,着重分析了固相初始浓度对排砂射流泵内流场、性能和效率的影响。结果表明:固相初始浓度越高势流核心长度越大,且固液两相混合完成的位置向喉管出口处移动;模拟得到的扩散管出口处浓度值随着固相初始浓度增加与理论值出现偏差,且浓度越大偏差越大,在初始浓度为20%时偏差值达到17.62%;砂粒的存在使得排砂射流泵特性曲线下降,在固相初始浓度为20%工况下,流量比M为1.2,相比于流量比M为0.3时,效率和压力比分别下降了52.38%和60.32%;在同一流量比工况下(M=0.7),固相初始浓度为20%时相较于单相流工况下,效率和压力比分别下降了25.92%和26.08%。     

煤岩与瓦斯固流耦合机理研究进展

论述了煤与瓦斯系统固流耦合理论及其模型研究成果,固流耦合理论主要有考虑煤体自身结构影响的渗流理论、流体自身影响的渗流理论、地球物理场影响的渗流理论,及综合考虑地球物理场与煤体结构影响的渗流理论。煤与瓦斯固流耦合模型有双孔隙介质影响模型、损伤影响模型、基质收缩影响模型、吸附膨胀影响模型、水气两相流影响模型、热量影响模型、煤体弹塑性影响模型、掘进工艺影响模型等8种。分析了各种模型的建立方法和研究内容,认为现有的煤与瓦斯固流耦合模型考虑因素各有侧重,难免轻重失当;尚未考虑掘进振动影响煤体渗流规律理论;且尚未研究掘进振动作用下含瓦斯煤体应力-渗流耦合模型。     

钻孔抽放瓦斯渗流特性的气固耦合模型

随着矿井开采深度的增加,地应力、瓦斯压力、煤体特性等因素的变化对瓦斯渗流的影响越来越明显。根据钻孔抽放瓦斯的渗流特性与固体变形的基本理论,引入了固体力学和多孔介质流耦合的控制方程,同时考虑了分子滑脱效应对渗流的影响。建立了考虑抽放钻孔在不同的地应力、不同初始渗透率和不同抽放负压条件下,瓦斯运移与煤体变形相耦合作用的数学模型。通过研究钻孔抽放瓦斯过程中,在不同地应力和瓦斯压力的影响下,得出煤层渗透率和瓦斯运移的变化规律。     

钻孔抽放瓦斯渗流特性的气固耦合模型

随着矿井开采深度的增加,地应力、瓦斯压力、煤体特性等因素的变化对瓦斯渗流的影响越来越明显。根据钻孔抽放瓦斯的渗流特性与固体变形的基本理论,引入了固体力学和多孔介质流耦合的控制方程,同时考虑了分子滑脱效应对渗流的影响。建立了考虑抽放钻孔在不同的地应力、不同初始渗透率和不同抽放负压条件下,瓦斯运移与煤体变形相耦合作用的数学模型。通过研究钻孔抽放瓦斯过程中,在不同地应力和瓦斯压力的影响下,得出煤层渗透率和瓦斯运移的变化规律。     

锌焙砂一段酸性浸出试验研究

对锌焙砂进行了一段酸性浸出试验研究,考察了搅拌速度、矿样粒度、浸出温度、初始酸度、液固比等因素对Zn和Fe浸出率的影响规律.试验结果表明:初始酸度和液固比是影响浸出的最重要因素,锌焙砂在55℃、初始酸度120 g/L、液同比6:1和搅拌速度为500 r/min的条件下浸出0.5 h,Zn的浸出率为81.33%、Fe的浸...     

磨料射流喷嘴外流场磨料速度模型及分析

喷嘴外流场磨料速度是建立磨料射流冲蚀深度模型的重要前提,以磨料射流喷嘴外流场磨料为研究对象,以固液两相流理论为基础,建立了磨料射流喷嘴外流场磨料速度模型,基于位移等分法和迭代算法求解了该速度模型,利用PIV实验进行验证,实测值与理论值的平均百分比误差在5%之内。并利用该速度模型得到了磨料射流喷嘴外流场磨料运动规律:(1)磨料颗粒流在喷嘴外流场的流动具有扩散性;(2)磨料颗粒沿射流轴向运动时,大多经历了一个先加速后减速的过程,只是加速距离有所差异;(3)初始段内相同轴向距离的射流横截面上,位于等速核区域内的磨料速度相同,随后磨料速度从等速核边界朝射流边界方向逐渐减小;初始段末端及基本段内相同轴向距离的射流横截面上,磨料速度沿射流径向的分布完全呈现出钟形速度分布。     

Effect of particle properties on particle percolation behaviour in a packed bed

Spontaneous inter-particle percolation is a very important phenomenon related to the mixing/segregation of particulate materials. Many studies have been conducted to understand the mechanisms governing the percolation behaviours in the past. However, previous work has a lack of systematic investigation on the effect of particle properties. In this work, a layer of small particles passing through a packed bed under gravity is analysed by means of the discrete element method. Percolation behaviour in terms of percolation velocity and radial dispersion is studied. The effect of percolating particle properties, including sliding friction and damping coefficients between percolating and packing particles, density and diameter ratios of percolating to packing particles and Young’s modulus of percolating particles, on the percolation behaviour is considered. It is observed that the damping coefficient and diameter ratio are the two dominant parameters that significantly affect the percolation behaviour. In particular, increasing the damping coefficient or decreasing the diameter ratio would increase the percolation velocity and decrease the radial dispersion. The sliding friction coefficient, Young’s modulus and density ratio have limited effects on the percolation behaviour. Two formulas have been, respectively, proposed to describe the dependences of percolation velocity and interaction force between percolating and packing particles on damping coefficient and diameter ratio.     

蒸汽相变凝结对PM2.5粒径分布的影响

基于多分散颗粒凝结增长理论,进行不同操作条件（停留时间、饱和度、温度）和PM2.5 特性（粒度、分散度）下相变凝结过程中颗粒粒径分布的研究,分析各参数对颗粒相变凝结增长效果的影响。结果表明：随着颗粒在过饱和蒸汽环境中停留时间的延长,颗粒粒径范围迅速变窄,颗粒由初始条件下多分散分布的微粒转变为单分散分布的粒径较大的含尘液滴;饱和度越大,相变凝结的推动力就越大,颗粒增长更为迅速;相同饱和度下,较高的温度能够促使PM2.5 成长为粒径更大的含尘液滴。研究发现,由于相变凝结后颗粒粒径趋于一致,初始PM2.5 粒径分布（粒度、分散度）对颗粒增长效果影响很小。     

Transport velocity of a crushed rock material bed on a screen

This paper describes a model which makes it possible to predict the transport velocity of a crushed rock material bed along an ordinary screen with a circular stroke. Transport velocity can be predicted with respect to the inclination, stroke and frequency of the screen. The model is based on physical laws. A particle leaves the screen surface when the negative vertical acceleration of the screen surface exceeds that of the particle. The particle can also slide along the screen surface. Monte Carlo simulation is used to estimate the influence of the other particles. Thus, random values are used to simulate the collisions between particles. The predicted transport velocity is equal to the average transport velocity from a few runs with the model. To verify the model, experiments were made: the transport velocity of a bed of crushed rock particles along a wire cloth was measured for different inclinations, strokes and frequencies. The predictions made with the model agreed well with the experimental results.A model which makes it possible to predict the size distribution of both the remaining and the passed material on a screen with several interacting screen planes has already been presented by the author. In addition, it is necessary to know the transport velocity of the material to be able to estimate the bed thickness and the capacity of the screening process.     

密度对细粒煤颗粒与气泡间相对运动的影响

颗粒与气泡间相对运动的研究对浮选机理的认识十分重要,目前关于颗粒与气泡间相对运动的研究多为理论推导,试验研究比较匮乏且试验对象多为形状规则,表面性质均匀的颗粒。以内蒙古公乌素原煤为研究对象,利用自行设计搭建的试验装置研究了粒级为0.100～0.074 mm、密度级分别为-1.3,1.4～1.5和+1.7 g/cm~3的煤样与气泡间的相对运动。试验通过追踪大量煤颗粒的运动轨迹,研究了颗粒沉降阶段、运动轨迹偏离阶段和碰撞阶段中颗粒运动特征参数的变化规律。试验结果表明:颗粒当量直径均值为0.092 mm,颗粒经短暂加速后便达到沉降末速,颗粒沉降末速随颗粒当量直径和密度的增大而增大。气泡会影响颗粒的运动轨迹,同一初始沉降区间内,竖直方向上煤样轨迹偏离点到气泡的距离随煤样密度的增大而减小。静水条件下颗粒和气泡碰撞角的主分布区间为20°～50°,且碰撞区间和颗粒集中分布区间随初始沉降区间向外扩展而扩展。颗粒和气泡的碰撞角小于50°时,碰撞点处颗粒速度减小比例随碰撞角增大近似直线减小,碰撞角大于50°时,碰撞点处颗粒速度减小比例趋于平稳,低密度颗粒的速度减小量大于高密度级颗粒的速度减小量,然而差异并不明显。理论计算发现,颗粒初始沉降位置距气泡中轴较近时理论碰撞速度较小,且颗粒理论碰撞速度随颗粒初始沉降位置向外扩展而增大,与试验规律较为吻合。     

The effect of particle size and some operating parameters in the separation tank and the downcomer on the Jameson cell recovery

The aim of this work is to investigate the effect of some operating variables and particle size on the Jameson cell performance. This is done by investigating the effect of varying different parameters such as concentrate flow rate and immersion depth of the downcomer for separation tank recovery, while jet length, jet velocity and holdup within the downcomer are used for downcomer recovery. It was found that altering these parameters play a significant role in recovery of different sized particles. An increase in concentrate flow rate and a decrease in immersion depth result in much more improving effect on recovery as particle size increases. An increase in jet length, jet velocity and holdup results in the recovery improvement for fine particles and loss of recovery for medium/coarse particles.     

Effect of slurry properties on particle motion in IsaMills

IsaMill? is a high-speed stirred mill for a range of milling duties from ultra-fine to relatively coarse grinding in the mineral processing industry. This work investigated particle and slurry flow in a mill using a combined Discrete Element Method and Computational Fluid Dynamics (DEM-CFD) approach. Slurry properties, such as flow density and viscosity, were varied to study their effects on the flow properties in terms of flow velocity, power draw, collision frequency, collision energy and total impact energy. Significant differences were observed when slurry was introduced and other conditions unchanged. With increasing density, fluid and particle flows showed stronger circulation in the axial direction due to the larger drag forces. Increased relative velocity and interaction between particles with disc led to higher collision frequency and collision energy. Increase in flow viscosity limited particles from moving towards the outer wall and the particles were more dispersed due to the larger circulating velocity in the axial direction. The total impact energy of the media and power draw also increase with slurry density and viscosity. The developed model provides a useful framework for further analysis of particle–slurry interactions in IsaMills?.     

煤颗粒密度和粒度及浓度对浮选效果的影响研究

为研究煤颗粒密度、粒度及浓度对浮选末速度的影响,构建了颗粒-气泡结合体模型,并在此基础上推导出了其上浮末速度计算公式;运用上浮末速度计算公式可计算出不同密度、粒度、浓度时颗粒-气泡结合体的上浮末速度。计算结果表明:煤颗粒粒度越大,不同密度、浓度的颗粒-气泡结合体上浮末速差值越大;煤颗粒浓度越大,不同粒度、密度的颗粒-气泡结合体上浮末速度越接近。     

考虑炮孔密集系数及高程影响下质点峰值速度的预测模型研究

边坡爆破作业中产生的爆破振速过大,会对周围建（构）筑物造成安全隐患问题,而准确预测爆破峰值速度是爆破开挖的重要指标。基于量纲分析理论,推导并改进炮孔密集系数及高程影响下的质点峰值速度预测公式。结果表明：引入边坡坡度项 的经验公式预测精度均大于萨氏公式、及萨氏修正公式;推导并改进的预测模型可以准确地预测峰值速度,预测精度达到91.16%;对某边坡爆破现场进行试验测振,将实测爆破振动数据分别代入萨氏公式、萨氏修正公式以及通过无量纲理论推导的质点峰值振速公式进行非线性回归运算,得到改进的峰值速度公式与各峰值速度公式的相对误差分别为8.84%、13.32%、19.74%。炮孔密集系数的预测模型比萨氏公式、萨式修正公式的精度分别提高了10.90%和4.48%,并且在实际工程中取得了良好效果,说明了该预测公式的可行性,可为类似爆破工程提供参考。