料仓流型及改善贮料流动性分析

本文介绍了各种料仓流型,并详细分析了影响料仓流型的因素,尤其是装料形式、改流体对料仓流型的影响,为料仓设计、选择流型和改善散体流动措施提供了参考。     

粉体物料和料斗材料对料仓流型的影响

基于现有的实验数据 ,分析了粉体物料和料斗材料对料仓流型的影响。认为料仓设计的首选流型为整体流 ,形成整体流的料斗材料依次为不锈钢、铝合金、普通碳钢 ;料斗半顶角由实际物料和料斗材料确定。指出在一定半顶角下设计的“标准”整体流料仓 ,只适用于很小一部分粉体物料。     

粉体料仓的设计

介绍了料仓设计的基本方法, 包括流型选择、流型设计以及卸料口尺寸的确定方法等, 最后给出一个应用实例。     

料仓卸料流动特性及结构强度数值模拟研究

采用离散元法建立颗粒模型研究锥形料仓卸料流动特性,通过DEM-FEM耦合的方法分析料仓结构强度,将无内构件料仓与带有内构件料仓卸料流动特性以及结构强度进行对比分析.结果 表明,无内构件料仓卸料过程出现中心流流型易发生堵塞,卸料速度慢,而带有内构件料仓卸料流型基本符合整体流流型;带有内构件料仓静态/动态侧压力小于无内构件...     

料仓设计中物料阻流问题的探析

本文通过分析料仓中物料的流型、阻流原因、提出设计中的考虑因素及预防措施。     

大型重力式散料掺混料仓及其工业应用

提出一种高效、节能、连续式散料掺混料仓 ,适用于PVC等粉、粒状颗粒的大批量掺混操作。料仓设计对均化管数量、进料口孔型、物料流型、布孔规律等作出了科学合理的设计 ,同时给出该掺混料仓在工业应用中的使用测定数据。这种结构的料仓 ,物料停留时间分布合理、出口混合度高、性能稳定、可一次性完成PVC颗粒的均化要求     

CPFD在细颗粒料仓下料中的应用

借助计算颗粒流体力学(CPFD)的数值模拟方法,研究了细颗粒玻璃微珠在不同结构料仓内的下料特性,获得了料仓出口直径和半锥角对颗粒下料流动的影响。在实验室可视化下料平台开展了验证实验,模拟结果与实验结果吻合较好。模拟结果表明:下料流率与料仓出口直径2.5次方呈正比;料仓半锥角增大,下料流型从质量流过渡至漏斗流。CPFD模拟给出了料仓下料过程的细节信息,并获得了料仓结构对颗粒流动形态转变的临界面相对高度的影响。     

复杂流道结构料仓的下料流率预测

在实验室搭建的有机玻璃料仓下料平台上,分别以自由流动粉体玻璃微珠和黏附性粉体煤粉和聚氯乙烯为实验介质,针对无改流体(No-In)、封闭改流体(Con-In)和开放改流体(Ucon-In)三种情况所形成的不同流道结构,开展了粉体料仓下料及其流率建模研究,定量分析了改流体对粉体下料流率的促进作用,对比给出了玻璃微珠、煤粉和聚氯乙烯在不同流道结构料仓内的下料特性。研究表明,改流体的引入有利于提高料仓下料流率,Con-In促进流动效果最明显,对于流动性弱的煤粉,下料流率提升幅度达到最大的58%。基于剪切摩擦区的概念,提出流率校正因子F对最小能量理论方程进行了修正,将理想的料仓下料模型拓展至实际下料过程。进一步,对于Con-In,根据流道结构特征结合对粉体的受力分析,修正了模型中的锥角项;对于Ucon-In,基于粉体下料流动竞争机制,提出分阶段下料模式并关联了内层和夹层的下料流率,最终建立了复杂流道结构料仓的下料流率预测模型。该模型综合考虑了粉体物性、下料流型和流道结构的影响,可有效预测自由流动粉体和黏附性粉体流经传统料仓(No-In)和改流体料仓(包括Con-In和Ucon-In)的粉体下料流...     

电容层析成像在煤粉料仓下料中的应用

煤粉料仓下料是气流床粉煤气化工艺中粉体供料单元的重要组成部分,其安全稳定运行具有重大的经济意义。提出将电容层析成像（ECT）技术用于煤粉料仓下料,从而实现研究手段的可视化。在煤粉料仓下料系统上,通过线性反投影算法及图片累加技术,获得料仓出口管道截面的相对颗粒浓度分布图像和下料过程的二维流型图;对比分析了称重信号和ECT信号的时间序列曲线,并通过RSD统计方法定量描述煤粉下料的波动程度。结果表明,ECT研究与煤粉下料分区理论吻合良好,借助ECT可充分认识煤粉下料流型和气固作用特征。     

改善高压聚乙烯料仓吹风净化效果确保装置安全生产

分析了影响高压聚乙烯料仓安全使用的原因,找出了影响料仓吹风净化作用效果、引起料仓爆炸事故的原因,为此对料仓净化风入口元件进行了改造,并对改造效果进行了评价.     

Homogenisieren von Schüttgütern in Mischsilos

Homogenization of bulk solids in blending silos . Blending silos are used for blending and homogenization of large quantities of bulk solids. Depending on how the energy is introduced, we distinguish between pneumatic, mechanical, and gravity flow blenders. The different blending principles are described and the suitability of the blending systems for certain types of bulk solids is explained. Fluidized bed blenders are suitable for homogenization of free flowing fine powders. Gravity flow blenders are used for blending of granular bulk solids. Homogenization of cohesive powders is accomplished in mechanical blending silos. It is necessary for selection of a suitable homogenization system to know the fluidization behaviour and the flow properties of the respective bulk solids. These properties can be determined in laboratory tests.     

Application of particle image velocimetry (PIV) for deformation measurement during granular silo flow

The paper presents results of deformation measurements in dry cohesionless sand during free flow in small rectangular model silos using a non-invasive, indirect method called particle image velocimetry (PIV). It is an optical technique for measuring surface deformations from successive digital images. Laboratory model tests were performed with a mass and funnel flow silo to investigate the kinematics of the flowing sand. The measurements were carried out for granular flow in model silos without inserts and in a funnel flow silo equipped with three different types of inserts: cone-in-cone, inverted cone and double cone. The effect of the initial sand density and roughness of silo walls on the volumetric and deviatoric strain in sand was investigated. The accuracy of measurements was discussed. Advantages and disadvantages of PIV were outlined. The results were qualitatively compared with sand displacements obtained with colored sand layers and with the aid of X-rays (initially dense sand).     

Verfahrenstechnische und statische Aspekte der Siloauslegung

Process Engineering Aspects and Statics of Silo Design. Design of silos for flow is described, starting from the flow profiles developing during discharge. The respective flow profile depends on the flow properties of the bulk solids and on the silo geometry. Based on measured flow properties the determination of the maximum permissible hopper wall inclination to achieve mass flow and of the minimum dimension of the outlet to prevent arching and ratholing is demonstrated, taking into account time consolidation aspects. This yields the size of a feeder and the position of discharge aids. The flow properties are required additionally for structural design of silos. Flow of bulk solids in silos, especially the development of asymmetric flow channels, has a significant influence on the pressure distribution.     

粉体物料的掺混及混料仓

介绍了粉体混料仓的型式及掺混原理。根据粉体物料的流化性能与流动性能 ,以及混料仓内能量的提供形式及掺混方式 ,可就某一种混料仓对某一特定操作条件的适用性作出估计     

Wall pressure issues in the aeration of bulk material silos

Operators of bulk material silos frequently face various flow defects. These include defects in flow continuity, vaults, stick rings, and dead zones in the bulk material. The application of aeration systems in bulk material silos is an effective method used in order to eliminate the above defects. This paper presents a study of the effect of an aeration system on wall pressures σ_W of bulk material in a silo during a targeted bulk material aeration and relaxation process, and analyses the results in light of the calculation standards for designing bulk material silos, namely ?SN 73 5570 a DIN 1055.     

Numerical analysis of silo behavior using non-coaxial models

Granular solids in silos experience considerable principal stress rotations, which result in the non-coaxiality between principal stresses and plastic strain rates. This paper discusses the influences of the use of elastoplastic non-coaxial models for granular solids on predictions of wall pressure distributions in silos by using the finite element method. A well established non-coaxial model in geomechanics, the yield vertex model, is employed. Simulations are performed on a steep hopper characterized with a mass flow and a flat-bottomed silo with a semi-mass flow. The simulations indicate that the non-coaxiality does not influence predictions of wall pressures after filling. On the other hand, the predicted discharge wall pressures with non-coaxial considerations are larger than those without it. Its mechanism is discussed in this paper. The suppressed shear-dilatancy of granular solids in silos leads to a larger increase of normal stress with non-coaxial models.     

Sicherheitstechnische Fragen beim Silobetrieb mit Ölsaaten und Extraktionsschroten

Aspects of Safety in the Operation of Silos Handling Oilseeds and Extracted Meals Some major aspects of technical safety in the operation of silos are discussed. In addition to the regulation dealing with charging of silos, the safety data for dusts are presented. Data derived from dust explosion tests, carried out with a simplified Hartmann apparatus, are given for several types of dusts from oilseeds and extracted meals. Problems related to the presence of hexane in extracted meals are discussed.