三产品重介质旋流器与两段两产品重介质旋流器分选效果对比研究

为了比较三产品重介质旋流器和两段两产品重介质旋流器的分选效果,以公乌素选煤厂三产品重介质旋流器和两段两产品重介质旋流器为研究对象,完成了两种旋流器入选原煤、精煤、中煤、矸石的采样,并通过筛分、浮沉试验,系统地对比了入料中各粒级煤的分选效果,研究结果将对两种旋流器的分选效果和机理有一个量化、科学的理解和认识。     

高含量重密度组分煤重介质旋流器分选特性研究

为了提高重介质旋流器对高含量重密度组分难选原煤的分选效率，设计了新型重介质旋流器模型装置，建立了颗粒在离心旋转流场中沉降分离数学模型，采用试验与理论分析相结合的方法研究新型重介质旋流器的分选特性，揭示高含量重密度组分难选煤分选特性随工艺参数的变化规律，探索影响新型重介质旋流器流场工作悬浮液动态稳定性的因素及重产物排料输运机制。研究结果表明，新型重介质旋流器分选高含量重密度组分煤时，底流重产物排料能力强、处理量大；离心旋流场中的悬浮液密度梯度分布小、密度相对均匀，底流与溢流密度差值较低，流场中悬浮液稳定性更强；入料的压力与悬浮液动态稳定性、分选精度及重产物排料效率直接相关，随着入料的压力增大，底流、溢流口排出悬浮液密度差值增大，可能偏差E值降低，分选精度提高，重产物排出量升高；当入料的压力为25 kPa时，实际分选密度为1.666 g/cm³,可能偏差E值为0.09 g/cm³,重产物产率为75.23%。本研究为高含量重密度组分煤的分选提供了新的思路。     

两产品大直径重介质旋流器分选下眼的探讨

介绍了在钱家营矿进行大直径旋流器分选下限的现场工业性试验过程及其试验结果,从而判定该重介旋流器的分选下限大于或等于0.5mm,此时,入料的各粒级均能得到不同程度的分选.     

两产品重介质旋流器排矸工艺在大同矿区的应用

大同矿区原煤排矸后可以满足优质动力煤产品的质量要求,两产品重介质旋流器排矸工艺、三产品重介质旋流器排矸工艺在该矿区均有应用;传统观点认为三产品重介质旋流器二段对悬浮液有浓缩作用,排矸灰分更高,矸石更纯,带煤量更小。生产实践表明:在保证分选密度的前提下,两产品重介质旋流器可获得与三产品重介质旋流器相同的排矸灰分和分选精度;在满足生产需要的同时,两产品重介质旋流器的分选精度、处理能力、单位能耗等更具优势。     

DZX1000型大处理量两产品重介质旋流器的研究

阐述了两产品重介质旋流器的发展现状,在对其分选原理、影响分选效果的因素等方面进行深入分析的基础上,研制了DZX1000型大处理量两产品重介质旋流器,结合计算机流体力学仿真软件对该旋流器内部流场进行了分析,针对旋流器的磨损特性进行了防磨处理,并介绍了其现场应用效果。     

新型两产品重介质旋流器的数值模拟研究与实践

结合两产品重介质旋流器的工作原理,从研究流体流动规律着手,利用FLUENT软件对新型和常规型两产品重介质旋流器进行流场数值模拟,对比分析得出:在相同工况条件下,新型旋流器具有能耗低、分选精度高、处理量大、使用寿命长的特点。     

NWSX—710/500新型三产品重介质旋流器

NWSX—710/500新型三产品重介质旋流器集已有重介质旋流器的优点,如无压给料、切向排矸、以单一低密度悬浮液系统一次分选出精煤、中煤及矸石三种产品;同时,实现了二段分选密度的灵活适时调节。实践表明:分选指标先进,即使原料煤质波动很大,精煤及中煤的质量均能得到保证。用它取代跳汰机,不仅能获得很高的分选精度和简便操作系统,而且可降低基建投资和生产成本,应用前景十分广阔。     

大型高效两产品重介质旋流器的研究与应用

阐述了当前两产品重介质旋流器存在的不足,设计开发了蜗壳入料型两产品重介质旋流器,并结合计算数值模拟技术对新型旋流器的内部流场进行了分析,得出新型旋流器具有处理量大、分选精度高、能耗低的优点。进行了工业应用,使用效果良好。     

氧化煤泥的重介质旋流器分选研究

利用实验室系统进行了重介质旋流器分选煤泥的半工业性试验,研究了入料压力、悬浮液密度等对氧化煤泥分选效果的影响,并通过理论模型对影响煤泥分选效果的主要因素进行了分析。结果表明:煤泥重介旋流器可以实现对煤泥的分选降灰,加重质粒度、悬浮液黏度、离心因数等,是影响有效分选煤泥分选效果的主要因素。     

Numerical simulation of magnetite segregation in a dense medium cyclone

Numerical simulations of turbulent driven flow in a dense medium cyclone with magnetite medium have been conducted using Fluent. The predicted air core shape and diameter were found to be close to the experimental results measured by gamma ray tomography. It is possible that the Large eddy simulation (LES) turbulence model with Mixture multi-phase model can be used to predict the air/slurry interface accurately although the LES may need a finer grid. Multi-phase simulations (air/water/medium) are showing appropriate medium segregation effects but are over-predicting the level of segregation compared to that measured by gamma-ray tomography in particular with over prediction of medium concentrations near the wall. Further, investigated the accurate prediction of axial segregation of magnetite using the LES turbulence model together with the multi-phase mixture model and viscosity corrections according to the feed particle loading factor. Addition of lift forces and viscosity correction improved the predictions especially near the wall. Predicted density profiles are very close to gamma ray tomography data showing a clear density drop near the wall. The effect of size distribution of the magnetite has been fully studied. It is interesting to note that the ultra-fine magnetite sizes (i.e. 2 and 7 μm) are distributed uniformly throughout the cyclone. As the size of magnetite increases, more segregation of magnetite occurs close to the wall. The cut-density (d₅₀) of the magnetite segregation is 32 μm, which is expected with superfine magnetite feed size distribution. At higher feed densities the agreement between the [Dungilson, 1999; Wood, J.C., 1990. A performance model for coal-washing dense medium cyclones, Ph.D. Thesis, JKMRC, University of Queensland] correlations and the CFD are reasonably good, but the overflow density is lower than the model predictions. It is believed that the excessive underflow volumetric flow rates are responsible for under prediction of the overflow density.     

无压三产品重介质旋流器二段技术改造与应用

针对屯兰选煤厂中煤灰分高而发热量低,难以满足电厂燃煤要求的问题,根据3GDMC1200/850A型无压三产品重介质旋流器结构特点和有关试验数据,在不影响旋流器一段分选效率和分选精度的情况下,对其二段进行技术改造。经此改造后,该选煤厂旋流器二段能够实现实时调控,中煤灰分稳定在33%~35%之间,发热量在18.22 MJ/kg左右,这为中煤产品指标合格提供了有力保障,也为选煤厂同类型旋流器未来的技术改造提供了良好借鉴。     

超级无压给料三产品重介质旋流器的研究与应用

介绍了S-3GHMC型超级无压给料重介质旋流器的工作原理和结构组成,阐述了该设备在确保高分选精度的前提下,大幅度提高处理能力和低分选下限的技术措施,并列举两座选煤厂使用S-3GHMC超级无压给料重介质旋流器而取得的工艺技术指标。     

A comprehensive CFD model of dense medium cyclone performance

A computational fluid dynamics (CFD) model of the dense medium cyclone (DMC) has been developed, using Fluent, by coupling component models for the air-core, the magnetite medium and coal particles. Simulations of turbulent driven flow in a dense medium cyclone with magnetite medium showed that the predicted air-core shape and diameter were close to experimental results measured by gamma ray tomography. Multiphase simulations (air/water/medium) using the large Eddy simulation (LES) turbulence model, together with viscosity corrections according to the feed particle loading factor, gave accurate predictions of axial magnetite segregation, with results close to gamma ray tomography data. Addition of lift forces and viscosity correction improved the radial magnetite segregation predictions especially near the wall. Predicted density profiles are very close to gamma ray tomography data, showing a clear density drop near the wall. At higher feed densities the agreement between the empirical correlations of [Dungilson, M.E., 1998. A model to predict the performance of the dense medium cyclone for low and high density applications, In: Seventh JKMRC Conference, Brisbane, Australia, 67–84; Wood, J.C., 1990. A performance model for coal-washing dense medium cyclones, Ph.D. Thesis, JKMRC, University of Queensland] and the CFD are reasonably good, but the overflow density from CFD is lower than the empirical model predictions and experimental values. It is believed that excessive underflow volumetric flow rates are responsible for under prediction of the overflow density.The partition characteristics of the DMC for particles between 0.5 and 8 mm in diameter were modeled using Lagrangian particle tracking. For the first time, the pivot phenomenon, in which partition curves for different sizes of coal pass through a common pivot point, has been successfully modeled using CFD. The values of E_p predicted by the Lagrangian particle tracking are very close to the experimental values although cut-point predictions deviate slightly. This comprehensive CFD model provides a tool for new DMC design with clear advantages over approaches based on constructing and trialling new designs experimentally.     

重介质旋流器分选效果的研究

针对影响石板选煤发电厂重介质旋流器分选效果的有关因素进行分析,阐述了进行技术改造所采取的相应措施。技术改造前后的对比试验表明,改造后的重介质旋流器的分选精度得到提高,分选效果良好。     

无压给料三产品重介质旋流器在荣辉选煤厂的应用

介绍了无压给料三产品重介质旋流器的分选原理及技术特点,结合原煤性质,分析了其在荣辉选煤厂的实际应用状况及分选效果。现场应用表明:无压给料三产品重介质旋流器具有分选精确度高、煤质适应性强、调节操作简单、自动化程度高等优点。     

重介质旋流器选煤技术分析

重介质旋流器选煤技术采用了低密度分选,自动化分选,分选效率高,节省了人力并且操作十分简单,因此重介质旋流器在选煤业的地位越来越高。如何进一步完善重介质旋流器选煤技术也就成为了选煤业的一个重要的课题。本文根据重介质旋流器的工作特点以及该技术最新的发展情况进行分析。     

Numerical studies of the effects of medium properties in dense medium cyclone operations

A mathematical approach is proposed to describe the multiphase flow in a 1000 mm industrial dense medium cyclone. A mixture multiphase model is employed to describe the flow of the dense medium (comprising finely ground magnetite contaminated with non-magnetic material in water) and the air core, where the turbulence is described by the well established Reynolds stress model. The stochastic Lagrangian particle tracking method is used to simulate the flow of coal particles. The proposed approach was qualitatively validated using literature and industrial data and then used to study the effects of medium properties including medium density, magnetite type and non-magnetic content. It is found that as the medium density increases, the pressure drop increases, resulting in a high pressure gradient force on coal particles and reduced separating efficiencies. The segregation of magnetite particles becomes serious as magnetite particle size increases, which leads to a high density differential and a high off-set. The viscosity of medium decreases and the segregation of magnetite particles become significant with the decrease of non-magnetic content, resulting in a high density differential and off-set.     

两产品重介旋流器主选底流脱介方式的探讨

与三产品重介旋流器选煤工艺相比,两产品重介旋流器主再选工艺灵活,中煤产品质量易于控制,但增加了主选底流脱介环节。通过三座选煤厂的设计实例,对比介绍了两产品重介旋流器主再选工艺中,主选底流弧形筛脱介、弧形筛+水平振动筛、固定筛+香蕉筛联合脱介方式及设备选型的优缺点,并针对不同脱介方式对系统介质平衡的影响提出了具体解决措施,在实际应用中均达到了预期效果。