常用化工流程模拟软件发展概述

化工流程模拟软件在化工过程的设计、研究、优化等方面发挥着十分重要的作用。本文概述了国内外化工流程模拟软件的发展情况,对目前应用最广泛的化工流程模拟软件进行了简介和对比。     

一种化工流程模拟的辅助输入系统

本文介绍一种化工流程模拟的辅助输入系统,其作用是帮助用户正确、快速、方便地编制该化工流程模拟的输入程序,简化其操作,提高化工流程模拟软件的利用率。该系统不仅解决了用户编写输入文件难的问题,而且大大节省了用户上机时间,促进该化工流程模拟软件系统在我国的推广使用。     

现代化工流程报警系统分析及管理策略

分析了现代石化流程报警系统现状,结合现代化工流程报警的特点,提出了适合于化工流程的合理设置报警系统的管理方法与策略,提出的报警管理思想对于现代化工流程报警系统的有效管理具有较强的实用性。     

化工流程模拟技术及应用

流程模拟技术与应用在当今的化工领域倍受关注,文章综述了化工流程模拟技术在国内外的发展历程和应用情况,同时,分析了目前我国在该项技术发展中存在的问题.最后阐述了化工流程模拟技术的发展趋势,并提出充分利用现代化的流程模拟技术是企业挖潜增效、节能降耗的有效途径.     

流程模拟技术在化工专业教学中的应用研究

结合多年从事化工流程模拟优化技术的实践经验,从培训策略、案例设计和效果评价等方面介绍了化工流程模拟软件辅助化工专业教学的应用方法,帮助学从系统工程的角度理解化工专业课程的紧密联系,培养学生解决工程实际问题的能力。     

电子计算机在化学工业中的应用(二)

1.化工流程的物料及热量平衡计算将化工流程计算分解为基本的单元操作问题,并分别建立一些通用的数学模型作为该系统的结构单元,其中每一种单元完成某一种特定的单元操作计算。根据计算要求,按照一定的次序,把相应的短小简单的结构单元连接起来,便可形成所要求的化工流程模型,再结合必需的计算参数、物流数据及物性数据,便可在计算机上进行化工流程的计算。这种计算机算法系统称为化工流程模拟系统,这个方法的优点是:当编写好了基本的结构单元程序模块以后,便可非常简单地组成任何复杂流程的工艺过程。借助于这些流程     

基于流程模拟软件平台的化工计算教材编写

为了适应化工流程模拟软件应用日益普及的现状,我们编写了以强化训练学生计算能力为目标的《化工计算与软件应用》教材。本文分析了传统化工计算教材内容的不足,阐明了选用流程模拟软件作为化工计算主要工具的必要性,介绍了新教材编写过程中内容组织、章节安排、编写风格的考虑,对新教材教学方式的变革提出了意见。本教材在校内使用两年来效果明显,学生应用化工流程模拟软件进行工艺设计的能力大幅增强。     

浅谈流程模拟软件在化工原理教学中的作用

本文结合多年的从事流程模拟与优化技术的实践经验和化工原理教学经验,从理论教学、课程设计和实验教学等三个方面介绍了流程模拟软件在化工原理教学中的作用.实践表明,采用流程模拟软件辅助化工原理教学的方法,不仅有助于学生获得对各种单元过程的深刻理解和工程判断能力.而且有助于培养学生利用流程模拟与优化技术解决工程实际问题的能力.     

Aspen Plus在化工中的应用

Aspen Plus是基于稳态化工模拟、优化、灵敏度分析和经济评价的大型化工流程模拟软件,其广泛应用于化学与石油工业、炼油加工、生物及医药等方面。文章介绍了该软件的功能特点,综述了近几年来该流程模拟软件在化工工程中的应用成果及发展情况。     

乙烯齐聚化工流程熵产率最小化

乙烯齐聚反应合成液体燃油技术在军用和民用领域具有广阔的应用前景。基于有限时间热力学，对包含混合器、压缩机、换热器以及乙烯齐聚反应器的化工流程进行了建模与优化，计算给定癸烯产率条件下流程熵产率最小时的压缩机出口压力、换热器出口温度以及换热器与反应器的管外热源分布，并将优化结果与参考化工流程以及反应器熵产率最小的对应流程进行了对比。结果表明，换热器出口温度为608.18 K和压缩机出口压力为2.68 MPa时，流程的熵产率最小，优化后的流程熵产率相比参考化工流程下降了3.12%，相较于反应器熵产率最小对应流程熵产率降低了1.30%。研究结果对乙烯齐聚化工流程最优设计具有一定的指导意义。     

基于流热固耦合的熔盐泵转子动力特性分析

用ANSYS软件模拟了熔盐泵转子的应力与变形,研究了不同介质流量下非定常流动对转子部件的影响,考察了泵转子结构的模态性能. 结果表明,转子温度自叶轮部件沿泵轴向轴承逐渐降低,不同介质流量下叶轮内的最大等效应力均出现在叶片进口边与前盖板的结合处,泵轴与轴承的配合处出现了明显的应力集中,转子部件的最大变形出现在叶轮边缘,且最大等效应力和变形量均随介质流量增大而减小,设计流量下转子部件最大等效应力和总变形量的变化幅度最小,添加预应力后转子部件前6阶固有频率增加,但振幅变化不大,流量对转子部件模态性能的影响较小.     

Droplet Size Distributions of Liquid-Liquid Dispersions in Centrifugal Pumps

The generation of liquid-liquid dispersions with defined droplet size distributions is an important aspect for process equipment design. In this work, two centrifugal pumps with different impeller diameters were used to generate dispersions at selected operating points for a paraffin oil-water system. The droplet break-up phenomena within the centrifugal pumps were analyzed using a transparent pump design in combination with high-speed imaging. Droplet size distributions at centrifugal pump discharge nozzle were recorded with optical probe measurement technologies and evaluated by means of image processing using a neural network. The influence of impeller diameter, rotational speed, volumetric flow rate and dispersed phase fraction are discussed. Experimental data is correlated using fluid properties, operating data as well as centrifugal pump dimensions. The correlations developed from results of this work serve as a basis for the equipment design of centrifugal pumps.     

低比转速复合叶轮离心泵内的非定常流动特性

为了研究低比转速离心泵内由叶轮/蜗壳相互作用所引起的非定常流动特性,基于滑移网格和RNG k-ε湍流模型计算了具有4长8短复合叶轮离心泵内部的非定常流动。计算结果显示,离心泵内部速度和压力在空间上呈现高度非对称性,在时间上呈现高度非定常性。蜗壳第Ⅳ断面和第Ⅷ断面速度变化规律基本一致,周向速度沿蜗壳径向减小,第Ⅷ断面出现负的径向速度,流动最为复杂。叶轮和蜗壳的动静耦合是产生压力脉动的主要原因,压力脉动的频率受叶轮转频控制,主频为叶片通过频率。蜗壳周向的脉动压力幅值呈现上下波动,但从第Ⅰ断面到第Ⅷ断面其幅值整体上在逐渐衰退,直到蜗壳第Ⅷ断面达到最小。与定常计算相比,在设计点下非定常计算所得的有效扬程更接近实验值,说明非定常计算可以比较准确地预测泵的扬程。     

Performance Analysis of a Disk-Type Viscous Pump with Radial Pumping Grooves

A new disk-type viscous pump, with radial pumping grooves on its stator, is described and its performance analyzed. Its flow rate and discharge pressure relationship is found to be linear. Two proposed viscous pumps of this new design having slightly different dimensions are considered and compared to the recently reported design utilizing multilobes. Analyses on these two proposed pumps show that this new design exhibits higher flow rate characteristics than the recent multilobe design for the same pump size and rotor–stator clearances.     

Axial thrust of axial flow impellers

This paper presents an analysis of the axial thrust of axial flow high-speed impellers under a turbulent regime of flow of an agitated liquid. The axial thrust is calculated from the measured total axial force affecting the cylindrical fully baffled mixing vessel and from the radial profile of the axial component of the ensemble-averaged mean velocity in the impeller discharge stream. The results of experimentally determined values of the dimensionless criteria (thrust number and momentum number) are successfully compared with the axial thrust of the pitched blade impellers calculated from the theoretically predicted simplified radial profiles of the axial component of the mean velocity in the impeller discharge stream.     

Scalar mixing measurements in a continuously operated stirred tank

An LIF (Laser induced flourescence) line scan system was used to obtain unobtrusive scalar concentration measurements in a continuously operated stirred tank agitated by a radial flow Rushton turbine and an axial flow 60°‐pitched blade impeller. A better blending process was generally achieved in the axial flow field, with macro‐ and micromixing in the radial flow field being most complete with fluid injected into the radial discharge jet, and in the axial flow field with fluid injected from above into the rotating impeller. Local concentration levels and fluctuations scaled with the feed pipe flow rate, and the degree of concentration uniformity throughout the tank scaled with the impeller speed and increased with the cube of the power input.     

Hydrodynamics Characterization of an Ellipse Gate Impeller by Experimental and Numerical Studies

Hydrodynamics characteristics like flow pattern, shear rate distribution, power consumption, axial pumping capacity, mixing time, and mixing efficiency of an ellipse gate (EG) impeller were investigated by experimental and numerical methods. The numerical simulation results were validated by experimental data of power consumption and mixing time. Results indicate that the axial pumping number of the EG impeller is larger than that of any other reported large‐scale impeller under laminar regime, and that the shear rate formed by this impeller is less sensitive to Reynolds numbers. In‐depth analysis reveals the different function of each part of the EG impeller under different flow regimes. This impeller provides an almost similar mixing efficiency like the double‐helical ribbon impeller under laminar regime, but much higher mixing efficiency both under transitional and turbulent flow regimes.     

Experimental Analysis of Hydrodynamics Induced by a Moritz HAS Impeller in Laminar and Turbulent Regimes

The hydrodynamics induced by a Moritz HAS impeller are investigated using the PIV technique. The purpose of this study is to extend the knowledge of this kind of impeller, well known in turbulent flow, to the transition regime and laminar flow. Measurements of instantaneous velocity fields are synchronized with the position of the blade of the impeller. The periodic motion induced by the impeller blade rotation is measured by this conditional averaging. A triple decomposition is used to analyze the levels of turbulent kinetic energy and periodic kinetic energy induced by the impeller. In a turbulent regime, the impeller induces axial flow: the magnitude of periodic fluctuation is low compared to the turbulent one. In a laminar regime, the impeller induces a tangential‐radial discharge flow, and periodic velocity fluctuations are limited to the vicinity of the impeller.     

Investigation of laminar flow in a stirred vessel at low Reynolds numbers

Many mixing applications involve viscous fluids and laminar flows where the detailed as well as overall flow structures are important. In order to understand the fluid dynamic characteristics of low Re laminar flows in mixing vessels, the flow induced by a Rushton impeller for three Re namely, 1, 10 and 28, was studied both experimentally and computationally. It was found that for the highest Re, the flow exhibited the familiar outward pumping action associated with radial impellers under turbulent flow conditions. However, as the Re decreases, the net radial flow during one impeller revolution was reduced and for the lowest Re a reciprocating motion with negligible net pumping was observed. This behaviour has not been reported in the literature in the past and represents a highly undesirable flow pattern from the standpoint of effective mixing. The CFD results successfully reproduced this behaviour. In order to elucidate the physical mechanism responsible for the observed flow pattern, the forces acting on a fluid element in the radial direction were analysed. The analysis indicated that for the lowest Re, the material derivative of radial velocity near the blade tip is small thus a balance exists between pressure and viscous forces; the defining characteristic of creeping flow. The velocity and pressure forces are in phase because the velocity is driven by the pressure field generated by the rotation of the impeller. Based on these findings, a simplified analytic model of the flow was developed that gives a good qualitative as well as quantitative representation of the flow.     

Prediction of the Induced Gas Flow Rate from a Self‐Inducing Impeller with CFD

The complex task of describing computationally two‐phase turbulent flows in aerated stirred‐tank reactors was overcome by proposing that the gas flow rate in the hollow impeller can be estimated from single‐phase flow simulations of the liquid phase in the reactor: the pressure at the impeller surface obtained from liquid phase simulations can be related to the gas induction rate. A commercial lab‐scale reactor with a radial six‐bladed hollow impeller was chosen for the study. To validate the presented methodology, the induced gas flow rate was measured experimentally from the tracking of the position of bubbles in a dynamic sequence of flow images. Notwithstanding the simplifications assumed in the presented CFD methodology, good agreement has been obtained between numerical results and experiments.