Minimum spouting velocity of conical spouted beds

Existing correlations for predicting minimum spouting velocity in conical spouted beds have been found to give poor agreement with available literature data. A new correlation has been developed based on literature data to give much better prediction of the minimum spouting velocity for both small and pilot-scale conical-spouted beds.     

Drying Of Pastes In Spouted Beds Of Inert Particles: Design Criteria And Modeling

The drying of pastelike materials can be performed well in spouted beds (SB) of inert particles. In this work the drying performance of pastes in conical pastes in conical spouted beds is analyzed as a function of column dimensions, fluid flow characteristics and paste properties. imulated data on fluid flow together with the experimental results on drying of different pastelike materials are presented and discussed to provide criteria for the design of a conical spouted bed dryer for suspensions.     

油井采出液管式旋流预分水设备的放大设计

旋流分离设备逐渐成为油田解决高含水问题的关键技术之一,但放大后性能降低成为制约其工程化应用的主要因素。对比研究了直接理论设计、压力主导型相似放大设计和流量主导型相似放大设计3种放大设计方法;以处理量为1.0 m³/h的管式旋流预分水设备室内样机为原型,分别采用上述3种设计方法设计了处理量为10.0 m³/h的工程样机;通过数值模拟详细对比了流动特性,并开展了现场试验研究。结果表明,流量主导型相似放大设计方法所得设备不仅离心加速度最大而且轴向衰减率最小,最大切向速度衰减率仅为25.39%。该方法设计的工程样机在油田现场的运行效果与室内样机基本一致：当采出液含水率在75%~90%范围内时,在确保分水率大于50%的前提下,可以将水出口的含油质量浓度控制在1321 mg/L以下。综合来看,流量主导型相似放大设计方法具有计算周期短、实施方便等优点,可为旋流分离设备的放大设计提供理论指导。     

An Investigation into Pressure Fluctuations and Improved Modeling of Solids Friction for Dense-Phase Pneumatic Conveying of Powders

The aim of this paper is to investigate into flow mechanism with the help of pressure signal fluctuations analysis and modeling solids friction in case of solids–gas flows for fluidized-dense-phase pneumatic conveying of fine powders. Materials conveyed include fly ash (median particle diameter 30 µm; particle density 2300 kg m^?3; loose-poured bulk density 700 kg m^?3) and white powder (median particle diameter 55 µm; particle density 1600 kg m^?3; loose-poured bulk density 620 kg m^?3). These were conveyed in different flow regimes varying from fluidized-dense-to-dilute phase. To obtain information on the nature of flow inside pipeline, static pressure signals were studied using technique of Shannon entropy. Increase in the values of Shannon entropy along the flow direction through the straight-pipe sections were found for both the powders. However, drop occurred in the Shannon entropy values after the flow through bend(s). Change in slope of straight-pipe pneumatic conveying characteristics along the flow direction is another factor which provided indication regarding change in flow mechanisms along the flow. A new technique for modeling solids friction factor has been developed using a solids volumetric concentration and ratio of particle terminal settling velocity to superficial air velocity by replacing the conventional use of solids loading ratio and Froude number, respectively. The new model format has shown promise for predictions under diameter scale-up conditions.     

PX型高效旋风分离器的冷模放大试验

为了评价实验室小型冷模试验开发出来的新型高效旋风分离器应用到工业过程中的性能,在完全相同条件下进行了与成熟的PV型旋风分离器的大型冷模放大对比试验.介绍了试验装置以及试验方案、内容.试验结果表明,新的PX型旋风分离器比现有的PV型旋风分离器具有更好的分离性能,分离效率更高(约高0.5～1.1百分点)、压力降更低、处理气量更大,对于催化裂化装置的扩能改造十分有利.     

高Schmidt数下喷射器内湍流混合的多尺度模拟放大研究

本文从微观与宏观两个方面考察了喷射器的混合性能.利用CFD模拟软件Fluent 6.2求解了混合模型方程、流体流动方程及k-ε湍流模型方程,对不同结构、不同工况下的喷射器进行了考察,结果表明:1)在喷射器结构一定的情况下,喷嘴速度和引射流体速度比越大混合效果越好;2)在喷射器结构、喷嘴速度与引射流体速度比为定值的情况下,其绝对速度越小混合效果越好;3)在喷射器速度为定值的情况下,混合段直径与喷嘴直径比越小混合效果越好,二者之间存在着线性关系;4)在喷射器速度、混合段直径与喷嘴直径比为定值的情况下,其绝对直径越小混合效果越好,且二者之间存在着线性关系;5)在多数情况下,微观混合速度要慢于宏观混合,微观混合才是喷射器内混合过程的控制步骤.     

Development of enhanced three-dimensional printed packings for scale-up of distillation columns: A successful case study

This publication presents a general approach for the enhancement of packings regarding scalability, separation efficiency, and fluid dynamic properties using three-dimensional (3D) printing. The methodology is used to develop miniaturized, scalable packings for process development, and scale-up applications. For this purpose, a 3D printable computer-aided design version of the Rombopak 9M industrial packing (RP9M-3D), which is known for its positive scalability properties, was created. An initial characterization by means of computational fluid dynamics simulations and mass transfer measurements reveals positive but also negative design properties. These findings are used to create a more advanced, miniaturized packing structure, the XW-Pak. The evolved structure is compared to the RP9M-3D. The simulation and experimental results show that the enhanced packing, which is still in the early stages of development, exhibits higher separation efficiencies with improved scalability properties at the same void fraction and surface area than the RP9M-3D.     

A novel design of distribution zone in scaled-up PEM fuel cells based on active control of transverse flow

The flow distribution is of significance to the fuel cell performance and durability, which has been studied from a theoretical and practical level in this work. The transverse-flow-control-based mechanism behind flow distribution processes is revealed. The core lies in the reasonable generation and distribution of transverse flow, which are the prerequisite and co-requisite for flow homogeneity. For the dual purpose, a novel design of combined-mesh-type distribution zone is proposed incorporating central horizontal meshes and lateral vertical meshes. The design philosophy and methodology are clarified. Under these guidelines, the novel distributor design is applied to different flow field plate geometries including the shorter distribution zone, higher expansion ratio, and scaled-up fuel cell. Through organized and detailed simulations, two key geometrical parameters (porosities of central and lateral meshes) are quantified and the superior effect on flow distribution is validated.     

生物反应器模拟放大模型的构建

目的:构建完善的生物反应器放大模型,为反应器生产提供指导.方法:通过1.5,5,20,200L规模反应器的试验,对体积溶氧系数k_La、混合时间t_m的关联式及参数进行了优化探究,建立了生物反应器模拟放大模型,通过MATLAB搭建了Scaleuper放大系统.结果:对比试验结果最终k_La的模拟偏差在±15%以内,通过在t_m的关联式中引入临界转速的定义,对t_m的整体模拟偏差较原公式减少了17.4%,在±10%内,通过嵌入BP神经网络减小k_La的模拟偏差,BP模型模拟k_La偏差对训练数据范围最小可达0.1%.结论:基于经验关联式的反应器放大模型,在试验测得相关参数后模拟结果较优;利用神经网络对反应器模拟、放大是可行的.