基于VB与Matlab混合编程的换热网络综合夹点技术软件设计

基于VB和Matlab,对换热网络综合夹点技术的问题表格法进行混合编程。利用该程序能够直接求出换热系统所需的公用工程热物流和公用工程冷物流数值,并且绘制出组合曲线和总组合曲线。     

重整进料换热器夹点温度设计的讨论

重整进料换热器是催化重整装置的核心设备之一,反应进料和反应产物在此进行热量交换,提高进料温度、降低产物温度,直接影响重整进料炉和重整产物空冷器的负荷。夹点温度是重整进料换热器工艺设计中的关键参数。根据工艺流程模拟计算中的物流数据,作出相关温焓曲线,通过曲线可求出夹点温度。重整进料换热过程是有相变的换热过程,夹点温度是温焓曲线上温差最小处,应采用分区法计算对数平均温差。可根据设备总费用增量的回收期判断重整进料换热器夹点温度是否合适。重整进料换热器热端温差越大,夹点温度越高,两者几乎成正比关系,可根据热端温差来判断换热器的夹点温度。氢油比对重整进料换热器夹点温度的影响与热端温差相关,当热端温差固定时,夹点温度随氢油比增大而增大,对装置扩能改造时重整进料换热器的设计具有指导意义。     

基于夹点技术的海上原油处理系统换热优化

为提升海上原油处理系统用能效率,减少燃料消耗量并降低污染物排放,采用夹点技术进行海上原油处理系统换热网络优化。概述夹点技术的基本原理和夹点确定计算方法,以我国某海上油田原油处理平台换热工艺为例,通过分析冷热物流特性,计算知最小传热温差为13℃时公用冷源降为0,并以此作为基础重新设计原油处理换热网络。优化后换热网络换热器数量维持不变,公用热源负荷由4 912.6 k W降至3 654.3 k W,无公用冷源需求,年可节省天然气用量133.1万m3(标准)。基于夹点技术设计原油处理换热工艺为工程设计阶段提供参考和依据。     

过程整合的夹点技术

夹点技术是一种过程整合技术，它将热力学与系统工程相结合，用以分析工业生产流程中的能量流动，提高能量的利用效率。一、夹点的定义对任一换热网络中的物流，均可提取出热物流和冷物流。物流所含能量的特征可在温（度）一（值）图上表示出来。若把同一温度区间热物流的治值叠加起来，并在温一偿图上画出叠加后的温度一焰值关系曲线，就得到热组合曲线；用同样的方法可以构成冷组合曲线，如图1所示。因热物流在换热网络中被冷却，温度降低；冷物流在网络中被加热，温度升高，所以常把热组合曲线冠以向下的箭头，冷组合曲线冠以向上的箭头…     

利用夹点技术优化蒸馏换热网络

介绍夹点技术设计的基本原理及设计原则,采用Aspen Hx-net软件,运用夹点技术对某炼油厂常压蒸馏装置换热网络进行优化分析,确定最优传热温差△Tmin、最小公用工程用量和夹点位置,并对换热网络进行了优化.装置运行情况表明,优化后的换热网络节能效果明显,装置投资回收期仅8个月.     

基于最优夹点温差的换热网络优化设计

介绍了夹点技术基本原理及其在换热网络优化设计中的原则。利用ASPENPinch软件设计了一个有三股热股流、两股冷股流的换热网络，求得最优夹点温差是23．7℃，设计时取值23℃。夹点温差分别取10、23、30％进行换热网络初步优化设计，在相同换热器情况下，三者的总费用分别是44279、41931、42156美元／a。这证明采用最优夹点温差的换热网络经济性最好。     

夹点技术在LNG分馏换热能量优化中的应用

在天然气液化技术工程化研究中,LNG分馏工艺较复杂,且设备种类较多,存在热量利用不充分,公用工程消耗量大的问题,为了节约能源需要对换热网络进行改进。先使用HYSYS软件对分馏工艺进行模拟,得出系统工艺参数,分析现有换热网络能量消耗,得到最小换热温差,再运用夹点技术对分馏区换热网络提出了改造方案。通过改进和优化,充分利用脱乙烷塔底物流的冷量,将分馏区热公用工程消耗量降低了15%,冷公用工程消耗量降低了8%,使用夹点技术对系统工艺和设备参数优化的研究得到了良好的节能效果。     

芳烃厂异构化装置换热网络的节能改造

采用夹点技术对某芳烃厂的异构化装置进行了分析,并提出换热网络集成改造方案。从分析中可 知,现行换热网络需要加热公用工程34.13MW,而取夹点温度为20℃,可得最小加热公用工程量为 11.87MW,可见,该装置换热网络存在着较大的节能潜力。提出了两个节能改造方案:一个完全按照夹 点技术的设计法则,为最大回收热量方案,但投资费用较高;另一个方案,保持原有网络结构不变,为最 小变动方案,可以回收20.78MW的热量,投资费用较低。两个方案的投资回收期均较短。     

换热器最佳温度差的研究

在设计和选择换热器时,冷、热流体之间的温度差是首先要确定的参数。本研究表明：在高温换热器中,提高流体间的换热温差,可以减少换热器的面积;而在低温换热器中,较低的流体换热温差有助于热交换品质的改善。通过技术经济对比分析可以得到最佳的换热温差。分析研究了换热器设计中,如其对数平均温差不变,则换热器的热交换性能也不变这个普遍认可的观点。发现：即使当时数平均温差相同时,热交换过程的ｙｉｎｇ的损失也和流体进、出换热器两端的温度差之比有关。在相向流动的换热器中,热流体进口处的最佳温差值应该比其在冷流体进口处的值要大,热流体的比热容应该比冷流体的比热容要小。对于一个给定的热交换过程,可以应用本文所得的热论确定换热器两端的流体温差的最佳关系式或冷、热流体比热的最佳比率。     

常减压换热网络的优化改进和优化控制

对结构已定或正在运行的常减压换热网络,在操作夹点附近设置旁路,通过对旁路流量的优化控制,使换热网络在某些过程物流的流量、温度发生变化时,换热网络的换热仍能满足工艺上的换热要求,公用工程能量消耗在现有的换热设备的基础上接近最小公用工程消耗量。     

Unerroric of control of mutual compliance of the efficiency of hydrogen engines of unmanned vehicles in the conditions of mass production

The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO₂ and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized.     

小型锅炉烟尘测试时锅炉出力的计算

锅炉烟尘测试时,必须对锅炉出力进行测试。但监测中,许多小型锅炉往往不具备相关的计量装置和仪表,为解决这一问题,文章提出了用烟气量和空气过剩系数来计算锅炉的出力的公式,在实际使用中,该方法简单易行,其结果和实测值具有很好的一致怀。     

中国煤炭地下气化技术的发展

本文综述了煤炭地下汽化技术的国内外发展现状,对我国“长通道、大断面”煤炭地下气化新工艺给予了技术经济评述,并提出了发展煤炭地下汽化技术的政策建议。     

Review of theory of distortion and disintegration of liquid streams

Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined.     

MgO膨胀剂细度对MgO水化和水泥浆体膨胀的影响

基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁（MgO）,研究了该型MgO膨胀剂（MEA）细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析（TG DSC）分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。     

机车车轮多轴疲劳强度安全评定的研究

使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。     

Constructal optimization of the geometry of an array of micro-channels

This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed.     

Heat of vaporization of mixtures

General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996     

固体热辐射Yong性能分析

本文对漫灰均温物体在常物性条件下对外辐射传热的Ｙｏｎｇ值计算建立了数学模型。通过与物体内能Ｙｏｎｇ公式的数值计算比较,得出了辐射能量的Ｙｏｎｇ值不大于内能Ｙｏｎｇ值的结论。从初步的热射Ｙｏｎｇ值计算公式发现。Ｙｏｎｇ与物体表面辐射率有关。     

Measurements of concentration distribution of hydrogen jet using deflection of center of the laser spot

The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%.