浮阀塔板上两相接触状态及相状态转变规律的探讨

本文作者对锥心浮阀塔板上气液两相的接触状态进行了实验研究,认为主要有喷溅、混合泡沫和完全泡沫三种状态.在正常的气液负荷范围内系混合泡沫状态.文中探讨了两相接触状态的转变规律与塔板入口端的清液层高度以及塔板上的雾沫夹带率有良好的对应关系,从而确定了有两个转相点.此外,还对两相接触状态的转变机理作了初步分析,得出了计算相状态转变点的准数关联式.     

气液固三相并流系统流型的混沌识别

运用确定性混沌分析技术，研究了气液固三相并流系统散式鼓泡流、聚式鼓泡流、柱塞流、泡沫流及环状流压力波动信号的混沌动力学行为。结果表明，吸引子可以用来表征气液固三相并流系统的动力学行为，混沌特征参数相关维D2和K熵可以用来定量识别以上五种流型。以混沌定量识别为基础，给出了三相并流系统的流型图。     

塔板上操作工况的过渡和雾沫夹带转变点

塔板上两相操作工况与雾沫夹带量的变化相关。在某气速下连续改变液流速率,雾沫夹带量呈马鞍形的变化,最低点所对应的清液深度,Zc约30—40mm,定义为“雾沫夹带转变点”。 当清液深度低于转变点,两相处于喷射或喷射主导工况;反之,两相处于泡沫或泡沫主导工况,雾沫夹带转变点即两种工况的过渡点。工况过渡不是突变而是渐变。文中对影响雾沫夹带变化的因素及工况过渡的特点进行了讨论。 作者提出,流行的雾沫夹带计算式——Hunt公式一般只适用于泡沫工况而不适用于喷射工况的操作过程。     

Predicting pressure gradients in heavy oil—water pipelines

Experimental investigations of the flow of water‐heavy oil mixtures at velocities typical of oil‐field gathering systems show that continuous water assisted flow at very low pressure gradients can be achieved. The principal criterion to be satisfied in establishing this desirable flow regime appears to be use of sufficient water, with the velocity also playing a role. It also appears that oil viscosity and water fraction effects on pressure gradient are small provided the beneficial flow regime is established. The flows resemble core‐annular flow, which has been observed previously in Bitumen froth and water‐heavy oil flows, with an oil layer on the pipe wall. However, the correlation for pressure gradient is somewhat different from that reported previously for Bitumen froth flows.     

INSIGHT INTO DISTILLATION/ABSORPTION COLUMNS AND FCC RISERS USING GAMMA SCANNING TECHNIQUE

This paper presents the application of gamma ray scanning technique to distillation/absorption columns and FCC risers.The flow regime transition.clear liquid height,froth height.crestliquid height over the exit weir on a V-1 type valve tray and downcomer hydraulics were investigatedusing the scanning device previously developed.The solid distribution and coke deposition were experi-mentally simulated in a FCC riser simulator by employing a three dimensional scanning device devel-oped for the present investigation.The success of this investigation should shed a light forquantifying two-phase contact phenomena in various gas liquid and gas solid two phase flow system.     

气相夹带对蒸馏塔板效率的影响

本文给出了在完全泡沫状态或以泡沫为主的混合状态下进行蒸馏操作时包括气相夹带的板效率模型,导出了Lewis的第一、第二和第三种情况的板效率计算式,讨论了气相夹带对板效率的影响,并与FRI的实验值作了比较.     

筛型塔板在喷射及混合状态操作下三相传质性能

以空气-水-油(煤油及白油)为介质在600mm×150mm矩形冷模塔内测试了筛型塔板气液液三相传质性能。研究喷射及混合状态下,气速、液流强度、油水比等操作条件和塔板结构参数(孔径、开孔率)对塔板效率的影响。气膜和液膜控制的2种物系的实验表明,三相传质的板效率在喷射状态下明显高于混合状态。对测试数据进行关联,获得适用于喷射及混合状态下三相传质板效率的估算式。     

Experimental Investigation of the Froth Height in Columns with Sandwich Packings

Sandwich packings, consisting of alternatingly stacked conventional structured packings with different geometric surface areas, are promising for increasing capacity and efficiency of separation columns. Film flow and froth flow evolve along a stack, which requires comprehensive fluid dynamic analysis. In particular, the froth height is an essential parameter to determine the spatial extent of the flow regimes. Ultrafast X‐ray tomography and a 3D‐printed pressure drop profile measurement module were applied to independently estimate this parameter. The results are compared with existing correlations.     

Phase inversion and mass transfer during liquid–liquid dispersed flow through mini-channel

The present study aims to identify means of process intensification during liquid–liquid flow through a mini-channel. During liquid–liquid flow, depending on the flow conditions either the organic or the aqueous phase can be dispersed and with increase in flow velocity the dispersed phase can spontaneously invert to form the continuous phase or vice-versa. The present study aims to investigate the phenomena of phase inversion and its influence on mass transfer during toluene/acetic acid-water flow in a 1.98 mm glass mini-channel. It is observed that for organic phase as dispersed regime, higher mass transfer efficiency is achieved when the liquid–liquid mixture is in the phase inversion zone which marks the transition from organic to aqueous phase dispersion. The mixture velocities as well as the inlet concentration of diffusing species influence mass transfer characteristics in this zone. The results have indicated some interesting observations which can be exploited for process intensification in monolith and micro-reactor.     

Estimation of bitumen froth quality using Bayesian information synthesis: An application to froth transportation process

This study presents the design of soft sensors for estimation of bitumen froth quality in an oil sands natural froth lubricated (NFL) transportation process. One of the most important quality indexes for bitumen froth is the water content. Due to the variation in oil sands composition and the nature of multi‐phase process conditions, existing hardware sensors are not reliable enough to provide on‐line accurate water content measurement. Laboratory analysis result is obtained off‐line with large sampling interval and irregular time delay. Therefore, it is not sufficient for real‐time monitoring and control. To overcome these limitations, Bayesian information synthesis approach is proposed to fuse all the existing information to produce more reliable and more accurate real‐time froth quality information. This technique has been applied in Syncrude Canada Extraction operations; both monitoring and control performance illustrate the promising perspectives of the proposed approach. © 2012 Canadian Society for Chemical Engineering     

电阻层析成象技术在两相管流测量中的应用

介绍应用电阻层析成象 (ERT)技术测量两相流中的基本原理和ERT系统的基本结构 ;描述应用天津大学过程层析成象研究室开发的ERT系统样机 ,在实验装置上进行两相流流型识别的实验研究。提出应用ERT系统进行流型识别的基本方法 ;并通过重建图像和分析测量数据实现两相流流型的识别。实验结果证明应用ERT系统实现两相流流型和参数测量的可能性     

汽液液三相精馏总板效率的研究

在Oldershaw精馏塔内,对汽液液三相精馏筛型塔板上的传质特性进行测试,研究了泡沫工况下,汽速、液汽比等操作条件,表面张力梯度、界面张力、乳化液分散粘度等物系性质,以及油水体积比等多种参数对总板效率的影响、对测试数据进行关联,获得了适用于泡沫工况下汽液液三相精馏过程的总板效率估算式,此关联式对设备设计及操作优化有一定的参考价值.     

筛板由泡沫态到喷射态工况转变点的测定和模拟

The transition from froth to spray regime on sieve trays was experimentally studied in an air/water simulator with 300 mm diameter. It has been found that the regime transition occurs as the cleax liquid height is equal to the residual pressure drop on the trays. A convenient and accurate technique was proposed for determination of the regime transition point. ]Based on analysis of the transition process at a sieve hole, a new formula which can be used to correlate the experimental results was provided.     

A preliminary study of interfacial areas in vertical cocurrent,two-phase upflow

Pseudo-first order chemical absorption was used as the basis for determining the effective interfacial area available for mass transfer in gas-liquid, cocurrent, upward pipe flow. The study, which was performed in a 2.54 cm I.D. tube, encompassed the slug and froth flow regimes. The interfacial area displayed a strong dependence upon the coordinates of the flow regime map proposed by Oshinowo and Charles⁽¹⁶⁾. In addition, the systematic variation of surface area could be rationalized on the basis of flow regime geometry. Unfortunately the data could not be used to assess previous surface area models due to the unresolved diameter dependence of these models. Observations are also made concerning the apparently significant effect of chemical composition on interfacial surface area, and concerning the inadequacy of the popular methods used for estimating frictional pressure drop in vertical two-phase flows.     

Measurements of interfacial areas in cocurrent gas—liquid downward flow

Gas-liquid interfacial areas were measured for cocurrent downward flow of the two-phase mixtures in a 2.54 cm ID open tube. The liquid phase was a dilute solution of aqueous sodium hydroxide and the gas phase was a mixture of air and carbon dioxide. Interfacial areas were determined by sampling the liquid phase and applying the technique of absorption with fast chemical reaction. Data were obtained in the froth flow regime and in the falling bubbly film regime which does not occur in horizontal or vertical upflow. Measured interfacial areas ranged from 0.7 to 2.5 cm^?1. These values are lower than those for downflow in a 10-mm tube⁽¹⁰⁾ by a factor of about two, suggesting a dependence on the tube diameter. A correlation in terms of Jepsen's frictional energy dissipation parameter \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {\frac{{\Delta P}} {{\Delta L}}} \right)(V_L ^ \circ + V_G ^ \circ ) $\end{document} is presented for the interfacial area.     

基于模糊规则的多模型固相质量流量软测量

针对静电传感器无法给出颗粒质量流量绝对值以及多相流流动形态和结构变化影响传感器输出等问题,提出了一种基于分解合成的多模型加权平均的固相质量流量非线性软测量模型。在高压密相气力输送系统上,通过静电传感器获得大量试验数据,提取信号特征,利用模糊聚类算法将输入数据进行空间分区, 每一区间上用径向基函数（RBF）神经网络辨识出一个子模型, 再利用模糊推理将各子模型输出加权求和得到颗粒质量流量的估计值。该模型减小了流型对测量结果的影响,提高了测量精度。     

The effect of gas injection on the flow of immiscible liquids in horizontal pipes

The flow of two immiscible liquids and the influence of an additional inserted gas phase in horizontal pipes is investigated. The experiments are carried out in a transparent horizontal pipe with an inner diameter of 59 mm and a total length of 48 m. Experimental results are presented for the flow regimes of the two phase and three phase flow of oil, water and gas mixtures. The effect of phase inversion on the pressure drop is measured. The experimental results obtained for the three phase flow of oil, water and air indicate that drag reduction is possible by injecting gas in laminar flowing mixtures of oil and water. In the aerated slug flow regime of oil, water and air a water dominated and an oil dominated flow system can be distinguished. The pressure drop of the three phase flow system is of the magnitude as the pressure drop of the two phase flow of gas and the dominating liquid phase.     

筛板上液体横向流动时气泡的形成特性

An apparatus,desinged to simulate bubbling of a sieve tray operated in froth regime,was employed. Bubble contact angles in and above the incipient weeping regimer for an air-water-plexiglas system were investigated. The influence of both liquid cross-flow and gas up-flow upon bubble contact angles was examined. A model considering the influence of liquid cross-flow was developed to predict bubble size from a sieve hole in froth operation regime.The comparison shows that the bubble sizes predicted by the present model are consistent with our experimental values and the available published experimental data.     

Modeling the Relationship between Froth Bubble Size and Flotation Performance Using Image Analysis and Neural Networks

Machine vision technology now offers a viable means of monitoring and control of froth flotation systems. In this study the relationship between process conditions and the surface bubble size as well as the process performance in the batch flotation of a copper sulfide ore is discussed and modeled by neural networks. Flotation experiments are conducted at a wide range of process conditions (i.e., gas flow rate, slurry solids %, frother/collector dosage, and pH) and the froth mean bubble size along with the metallurgical parameters are determined for each run. An adaptive marker based watershed algorithm is successfully developed for segmentation of the froth images and measurement of the bubble size at different conditions. The results show that there is a strong correlation between process conditions and the froth mean bubble size, which is of great importance for control purposes. Even though the metallurgical parameters can be estimated from the froth mean bubble size alone, other froth features (i.e., froth velocity, color, and stability) are required to be measured in order to achieve more accurate predictions of the process performance.     

CHARACTERIZATION OF FLOTATION PROCESSES WITH SELF-ORGANIZING NEURAL NETS

Flotation processes are difficult to describe fundamentally, owing to the stochastic nature of the froth structures and the ill-defined chemorheology of the froth. Considerable information on the process is reflected by the structure of the froth. In previous work it has been shown that structural features extracted from flotation froths can be related to the behavior of flotation processes in a qualitative way through the identification of certain behavioral regimes or classes by using a supervised neural net as classifier. Although useful as an aid to control decisions, this method is less suitable for quantitative or dynamic analysis of the behavior of flotation plants. In this paper a new method for the analysis of flotation plants is consequently proposed, based on the use of order preserving maps of features extracted from digitized images of the froth phase. The construction of these maps by means of a self-organizing neural net is demonstrated by way of examples concerning the analysis of industrial copper and platinum flotation plants.