Setting the bar for powder flow properties in successful high speed tableting

An inadequate powder flow leads to problems in tablet manufacturing. The knowledge of minimum flow properties required for successful tableting on a high speed press is critically important to the efficient development of pharmaceutical tablets. This may be achieved by identifying a powder that exhibits minimally acceptable flow properties on a high speed tablet press. A grade of a common tablet excipient, microcrystalline cellulose (Avicel PH102) lies near the borderline between acceptable and poor flow regions during high speed tableting. It can therefore serve as a reference material for judging adequacy of flow properties of prototype formulations by the way of comparison. A powder exhibiting poorer flow properties than Avicel PH102 likely exhibits flow problems and should be avoided. An implementation of this simple approach in formulation development can minimize potential flow problems during large scale tablet manufacture.     

Explicit equations for laminar flow of herschel–bulkley fluids

There are three typical problems encountered in pipe flows: unknown friction factor, unknown flow rate, and unknown diameter problems. A major problem in determining the solution to these flow problems occurs due to the implicit nature of the Darcy–Weisbach friction factor. Though explicit equations for flow of Newtonian fluids and Power Law fluids are available, no such usable equations exist for Herschel–Bulkley fluids. In this paper, explicit equations have been given for flow of Herschel–Bulkley fluids in the laminar regime.     

A geometrically based grid refinement technique for multiphase flows

An adaptive mesh refinement technique developed for the solution of scalar problems is extended to the simulation of two-phase flow problems, as a means of reducing the computational runtime associated with such problems. The methodology, involving the adaptive partition of the domain into uniformly discretised regions, is extended to systems of equations without increase in algorithmic complexity. By application first to the simpler case of the Euler equations of gas dynamics, the technique is shown to handle shocks without loss of accuracy and to result in significant CPU runtime reductions of over 90%. Application to more complex two-phase flow problems, including the flashing flow during the decompression of a pipeline, also show dramatic increase in computational performance.     

并流多通道管壳式换热器壳程流场分布

对一种新型并流多通道进出口结构（MPC）轴流管壳式换热器壳程流场分布与阻力性能进行全面研究,分别研究了管排数、Reynolds数、不同挡板对壳程流场分布、阻力性能的影响,并且采用实验方法对数值模型与方法的正确性进行论证。研究结果表明,在无挡板的情况下,随着管排数的减小,壳程流场分布不均现象得到有效的遏制,压降大幅降低,最大降幅达到70％以上;挡板能够有效促进流场的二次分布,但是同时亦使阻力增大较为显著。     

水平管中油气水三相流动研究进展

对国内外油气水三相管流中的关键问题,如流型划分、油水反相以及水力计算(包括持液率和压降)等的研究成果进行综合评述,同时指出了研究中的问题所在和今后的研究方向。     

水平气液两相流管道振动实验研究

在分析水平气液两相流管道振动的典型问题及研究的基础上,利用气液两相流模拟实验装置及PL302双通道数据采集器等测试设备对水平气液两相流管道中的各种振动问题进行测试。并对测得的振动信号进行比较分析,得到上述振动问题的特性及规律,为今后研究该流动状态下的振动特性提供一定依据。     

气液两相流界面多尺度问题可计算性研究进展

气液两相流复杂多变的界面结构在瞬态时间上具有宽广的空间尺度范围.界面多尺度问题涉及化工领域、核安全领域以及其他多个领域,其可计算性是当前国内外气液两相流领域的研究焦点之一.分析了欧拉体系下处理气液两相流相界面不连续性的两种基本模型以及湍流模拟方法对界面结构的影响.针对离散流界面尺度分布性和混合流界面跨尺度性两类多尺度问题,分析了可计算性研究面临的困境,将其归因于网格尺度的约束、几何及物理边界的缺失.重点归纳了混合流界面跨尺度性问题的计算方法以及典型应用.最后对气液两相流界面多尺度问题提出了应对策略及研究趋势,为此类问题研究提供有益的参考.     

浅谈汽车涂装电泳

简单介绍了汽车车身电泳涂装工艺流程,从实际生产过程当中寻求影响电泳涂装的工艺参数,以及电泳涂装的方法与技巧,在实际工作中分析解决了电泳过程中出现的问题,例如电泳流痕、缩孔等质量问题。     

管道内油水两相流动研究进展

综述了国内外有关圆管中油水两相流动过程中的流型、相转换的研究现状,并重点介绍了油水垂直两相流中液滴粒径及分布、持液率、压力降计算等方面的研究成果。同时分析了研究中所存在的问题并指出了今后的研究方向,为进一步开展油水两相流研究提供相关参考。     

异型材成型挤出口模内的流动分析

采用润滑理论解决异型材挤出口模中的流动问题;采用横截面法求解垂直于流动方向的横截面上的速度分布;在流动速率已知的情况下,采用假定区域法求得压力降。     

Numerical simulation of moving free surface problems in polymer processing using volume‐of‐fluid method

We have developed a numerical algorithm based on 2D/3D finite element method for solving non‐Newtonian fluid flow with the moving free surface encountered in polymer processing. The power law model is considered as a rheological constitutive equation. The standard Galerkin finite element formulation/penalty formulation are applied to discrctize the governing equations, the volume‐of‐fluid (VOF) scheme is used to track the moving free surface, and the donor‐acceptor model introduced by Hirt and Nichols is modified and implemented on FEM. We applied the numerical scheme to simulate fountain flow and viscous buckling problems. For fountain flow, the numerical prediction of this study is in good agreement with the experimental results of other investigators. For viscous buckling, both 2D and 3D numerical simulations show that the shear thinning effect retards buckling. As this algorithm is very effective in treating moving free surface problems and requires less memory than previous algorithms, it may help solve challenging problems in polymer processing such as transient visroelastic flow simulations with moving free surfaces.     

Advanced simulation of transient multiphase flow & flow assurance in the oil & gas industry

We discuss here current computational trends (beyond Mechanistic 1D Models) related to transient multiphase flow and flow assurance problems in the oil and gas sector. The developments needed to bring advanced Computational fluid & Multiphase‐fluid dynamics (CFD & CMFD) techniques and models to a mature stage will also be discussed. The contribution presents the possibilities offered today by these simulation technologies to treat complex, multiphase, multicomponent flow problems occurring in the gas and petroleum engineering in general. Examples of various degrees of sophistication will be presented, without focusing on the validation aspect as such. The models are briefly introduced (phase averages, N‐phase, interface tracking, Lagrangian particle tracking and granular flow model). © 2013 Canadian Society for Chemical Engineering     

列管式废热锅炉火管管间液体流速场和温度场的试验研究

本文对列管式废热锅炉火管管间液体流速场和温度场进行了实验研究.采用W1269型水热膜探头和1050型热膜风速仪测定了流场速度分布,用铠装热电偶测量了工质温度分布,并就出水口位置的影响进行了研究,根据实验结果对流场进行了分析,解释了实际应用中上管板经常变形和泄漏等事故的起因.     

ON NONISOTHERMAL FLOWS OF BINGHAM PLASTICS

A numerical scheme based on the Galerkin's finite element method is used to analyze nonisothermal flows of Bingham plastics. These fluids exhibit yield stresses, below which the material does not flow. This condition is enforced by introducing the bi-viscosity model in which the plug behaviour is approximated by a highly viscous fluid. The bi-viscosity model approaches the ideal Bingham plastic model if the pre-yield viscosity becomes large. This numerical method is applied to solve three problems namely the Graetz-Nusselt, recirculating flow, and sinusoidal channel flow problems for various values of the yield stress. The size of the plug as well as the velocity and temperature fields correspond closely with values available in literature.     

The significance of slip of polymer melt flow

Some recent observations of catastrophic yielding or bimodal flow behavior in linear polyethylene melts have indicated certain inadequacies in the commonly accepted flow theories and practices. Examples of some “non-ideal” behavior are presented along with some evidence that slip at or near the polymer-die interface, rather than a flow phenomenon, is the mechanism associated with the discontinuity in the flow curve. The discontinuity shear stress is observed to be independent of hydrostatic pressure. The significance of this bimodal flow behavior is related to polymer processing problems.     

氟硅酸钠干燥采用振动流化床干燥器

磷肥工业中副产的氟硅酸钠大多采用气流干燥。介绍采用振动流化床干燥的工艺流程，风量、风压的配置以及操作要点，并指出存在8问题和处理方法。     

带切断阀的椭圆齿轮流量计电源板的改造

通过对年产18万t PET装置上使用的带切断阀的椭圆齿轮流量计的原理分析,提出并解决了由于供电模块故障导致流量计不能使用的问题。所设计的新供电方案避免了采购原装备件周期长、费用高,影响生产的问题,为进口设备备件国产化做了有益的尝试。     

Offene Probleme in der Rührtechnik

Open problems in stirring technology . In this article, an attempt is made to show those problems which still have to be solved largely by empirical methods. The list of problems is by no means complete, and many of them may still not be regarded as a problem by specialists. Nevertheless, the problems of stirring technology are shown in the framework of its development to date in order to indicate possible developments for the near future. Thus greater attention to fluid mechanics (turbulence, non-Newtonian liquids, large volume flow) could be of advantage. Simplified model concepts which analytically describe at least part of the complex stirring and mixing process are desirable. Departure from frequently uncritical application of dimensional analysis and inclusion of flow mechanics and chemical engineering reasons for ensuring mechanical loads would help to solve many a problem.     

单塔连续精馏工艺在粗苯初馏的应用

本文介绍了单塔连续精馏工艺的工艺流程、工艺原理、开工步骤及运行中出现的问题,并对问题进行了分析,在生产中排除了故障。该工艺在焦化行业有一定的推广意义。     

The effect of preheater design on corrosion,heat transfer and operation of MSF-distillers

The paper reports of investigations to analyse and solve severe corrosion problems in two 11.500 m³/d MSF desalination distillers in operation since 1976. A careful examination of the distiller situation, the operation behaviour and the design features evidenced, that the problems were caused by neglecting certain design rules for the condensers. It can be shown, that essentially the same errors are often responsible for poor thermal performance and operation instabilities in other plants. One element of the investigation was an experimental simulation of the vapour flow in the condensers by a water flow model. It was possible to visualize and study the actual vapour flow patterns and to detect zones of stagnant vapour.