利用模型试验台研究管道输送阻力特性

随着管道输送固体物料的广泛应用,水力输送技术的研究越来越受到重视。本文介绍了一台操作简便、自动化程度高的模型试验台,并利用该试验台对管道输送中阻力损失特性进行研究。     

煤粉气力输送过程中采用不同输送管径的数值模拟研究

气力输送是工业上普遍使用的输送物料的方法,目前研究方法主要包括实验研究和数值模拟两部分。本次模拟主要针对煤粉气力输送实验过程中所选用的不同的输送管道半径对压力损失和输送量的影响,与实验数据进行对照,评价数值模拟的准确性,然后针对拟定的工业装置及工况开展模拟分析,对实际生产过程作出预测并提供一定的参数支持。     

粉体密相管道气力输送特性研究

本文重点评述了物料特性对密相气力管道输送特性的影响,系统地探讨了密相气力输送阻力特性、数值模拟近些年取得的研究进展,最后对存在的问题及研究的方向提出意见。     

高浓度水煤浆流变特性和稳定性试验研究

水煤浆是由液固两相组成的非牛顿流体,流变性和稳定性十分复杂,影响因素也很多,其流变特性和稳定特性对管道输送和燃烧性能起着决定性的作用.借助于水煤浆粘度计对质量浓度为60%以上的水煤浆进行流变性测量,研究了温度、浓度和添加剂对煤浆流变性的影响,水煤浆的表观粘度随温度的升高而降低,随浓度增加而增大,添加剂的加入大大改善水煤浆的流变特性.通过对水煤浆稳定性的研究,得出了水煤浆的稳定性随浓度增加而增加,与煤种有关,适量的添加剂能改善稳定性,稳定性随温度升高而降低.从输送水煤浆总体经济角度看,水煤浆的输送温度在20y～40℃为宜.     

增压流化床用水煤膏管道输送的研究

通过试验研究了水煤膏在中小管道中输送的流变特性和阻力特性,分析了各影响因素对水煤膏流变特笥的影响,给出了水煤膏管内流动阻力的计算方法,研究表明,水煤膏的流变特性可用Herschel-Bulkley模型描述,适当配比的水煤膏可以很低水份下（22．16％）顺利流动,石灰石的添加可以降低水煤膏在管道内的流动阻力,层流态态下,水煤膏的阻力系数可用似于牛顿流体的广义雷诺数描述即,λ＝64／Reg.     

粉体密相气力输送研究综述

物料的输送特性、输送管道压损研究、输送相图以及数值模拟等方面评述了粉体密相气力输送在近些年取得的研究进展,结合东南大学关于高压密相气力输送已有的研究成果,提出一些干煤粉加压密相气力输送的研究方向.     

锂电池正极材料气流输送控制系统的研发

文中研发了一种锂电池正极材料气流输送控制系统,包括发射罐、三个收料仓、返投器、空气源和物料仓,发射罐与物料仓之间设有进料气动球阀,发射罐底部的下料弯管与三个收料仓气路连通,发射罐与返投器之间设有连接气动球阀,发射罐顶部与空气源之间设有空气导入控制阀组及三组防架桥气流导入控制阀组,下料弯管与空气源之间设有管道清理气流控制阀组,输送料管与空气源之间设有气流输送控制阀组;通过气流输送物料,输送效率高,物料及管道损耗小,管道使用周期长,无需频繁检修更换,操作使用方便,并通过多个阀门进行控制,物料输送更精准,自带管道清理及防架桥功能,并辅以自动称重、料位计算、压力检测等,系统更智能、输送更安全顺畅。     

浅床流化床飞灰回燃系统中的可调喷射器特性研究

一、前言在用喷射器输送物料方面，已经进行了不少工作［1］［2］［3］。［3］研究了在沸腾炉粉煤底饲系统中用喷射器输送煤粉，喷射器的输送能力仅靠改变喷咀入口处的压力来调节。为能采用其它方式调节喷射器的输送能力，我们研究了可调喷射器，建立了浅床流化床飞灰分离国燃系统实验台，利用它来输送回收的飞灰，通过试验获得了喷射器的可调间距、开度与喷射能力相应关系的规律。二、飞灰回燃系统图1为试验装置的原则性系统图。物料经给料装置进人喷射器中与来自输送风机的空气混合后经底饲喷咀进入旋风分离器进行气团分离，物料回收。图1…     

岩石单轴压缩流变参数的确定

针对单轴压缩流变试验确定流变模型参数难度大的问题,基于最小二乘法原理及蠕变本构方程,通过室内蠕变试验研究了软岩变形特征与时效特性,分析了试验数据并建立组合Burgers模型,利用数据处理软件对岩石单轴压缩试验结果进行曲线拟合,确定了该流变模型的本构参数.试验结果表明,该方法可行,为研究岩石特性提供了参考.     

旋转锥体床内颗粒传输规律的实验研究

该实验针对旋转锥体床,研究颗粒在锥体内的输运规律。探讨锥体旋转速率、颗粒给料速率、锥体溢流口数量等参数变化时,对颗粒在锥体内的动态存料量以及停留时间的影响。结果表明,旋转锥体床具有控制物料输送和调节停留时间的可操作性,增设竖立环壁将大大延长颗粒在锥体的停留时间,而搅拌器的设置对于保证颗粒在锥体内的充分混合起着关键作用。在设置竖立环壁和搅拌器的情况下,锥体内的动态存料量与给料速率成正比,而与锥体旋转速率反比;停留时间与锥体旋转速率和给料速率成反比。增加溢流口面积,将缩短颗粒停留时间和降低锥体内的存料量。研究结果对于设计新颖的煤热解气化炉以及开发以固体热载体热解气化为基础的多联产技术具有一定的参考价值。图10参8     

高浓度水煤浆的流变特性和流动规律研究进展

综述了高浓度水煤浆的流变特性、流动特性、阻力特性和均质稳定输送等方面实验和理论研究的国内外最新进展.深入讨论和分析了水煤浆的流变学属性及影响因素,探讨了浆态非牛顿流体流变特性的理论和实验分析方法中涉及的某些不确定性问题和解决方案,阐述了水煤浆管内输送的滑移机理及其对流动的影响.结合非牛顿流体力学、液固两相流、数值模拟和分析以及模化实验等先进的研究手段,提出了高压、高浓度水煤浆在流变特性、流动特性、阻力特性和均配规律等方面进一步深化研究的设想和思路.     

堤基管涌破坏过程中的声发射信号特性研究

通过自行设计砂槽模型,开展了堤基管涌连续破坏的室内试验,研究了堤基管涌连续破坏过程中的声发射信号特性。通过对比分析管涌连续破坏过程中测压管水头的变化与声发射特性参数,发现管涌连续破坏过程中有明显的破坏阶段性,可分为未发生管涌、管涌发生初期、管涌发生后期3个阶段。通过分析管涌连续破坏各个阶段声发射信号的波形,发现堤基管涌连续破坏过程的声发射信号多为突发型信号。利用二进离散小波包对声发射信号进行频谱分析,发现管涌连续破坏各个阶段的声发射信号主频主要集中在[0 62.5]kHz频带,管涌发生初期和管涌发生后期的声发射信号主频范围为20~30kHz,未发生管涌阶段则主频偏小为2~7kHz。     

Piping network design of geothermal district heating systems: Case study for a university campus

Geothermal district heating system design consists of two parts: heating system and piping network design. District heating system design and a case study for a university campus is given in Yildirim et al. [1] in detail. In this study, piping network design optimisation is evaluated based on heat centre location depending upon the cost and common design parameters of piping networks which are pipe materials, target pressure loss (TPL) per unit length of pipes and installation type. Then a case study for the same campus is presented.     

Design of supporting devices for large diameter thin pipes

When an analysis is made in accordance with ASME Code Class 1 for piping by the stress indices method (NB 3650), the stresses induced locally in the piping by the supports are not taken into account. For piping whose thickness is small in relation to its diameter, which is subject to sudden temperature changes and to seismic shocks and which also operates at high temperature, it is undesirable to ignore these effects. This is particularly the case with piping carrying liquid sodium since the classic solutions do not provide a satisfactory answer to the thermomechanical problems and cannot resolve many uncertainties in the analysis. The design finally selected must meet the double requirement of permitting free radial expansion of the piping whilst enabling it to withstand considerable loads with minimal deformation. The design must also be justifiable by easily verified hypotheses.The design adopted consists of a rigid collar connected to the piping by blades which are flexible radially in relation to the pipe and rigid tangentially. These blades are attached to very short ring lugs welded on to the piping. In this way, the outside forces acting on the piping are reduced almost exclusively to circumferential forces which, combined with the circumferential shearing flux due to the adjacent sections, constitute a distribution of forces which is particularly favourable for limiting the circumferential bending moments in the pipe. The resulting deformation of the circular section is thus sufficiently small not to affect the longitudinal bending strength, and particularly the buckling strength.The most significant stresses prove to be those due to the moment on the lug; these are well known and are limited due to the small height of the lug. The thermal stresses due to the presence of the lug were calculated by the finite element method. The thermal and mechanical disturbance created by the lug has the effect of multiplying by about a factor of 2 the maximum total stresses occurring during thermal transients in the straight part; they thus remain limited and less than those developed in other straight discontinuities affecting the piping; for instance, the changes in thickness between straight parts and bends. To back up these calculations, a series of tests was performed to check that the technological requirements of manufacture did not question the load distribution hypotheses taken into account in the calculations.     

Development of criteria for protection against pipe breaks in LWR plants

A proving test for the structural integrity of safety-related carbon steel piping components in light water reactor plants was conducted in NUPEC as a four-year project, in which the applicability of the Leak-Before-Break (LBB) concept to protect against a postulated pipe break was reviewed in parallel with the clarification of fracture behavior. The comprehensive review of LBB applications consists of applicable piping systems, premise for evaluations, procedure and evaluation findings. The review concluded that present practice for design, fabrication, installation and operation can ensure structural integrity and moreover postulated that instantaneous pipe break as a basis for structural design is unrealistic if certain conditions are met. Fatigue is the only failure mechanism to be considered to affect the piping system.     

Optimum insulation-thickness for thermal and freezing protection

Methods for protecting water pipes, in cold regions against freezing, by thermal insulation material and heating cable will be analyzed. Reliability of keeping the tube's wall temperature of a piping system at minimum value will be analyzed. A thermoeconomic optimization analysis is applied with a simple algebraic formula derived for estimating the optimum insulation thickness for tubes of different sizes. The optimization is based on a life-cycle cost analysis. The effects of design parameters on the optimum thickness are investigated. Predicted results of this study would provide useful reference data when considering design, practical operation or maintenance.     

Optimum X-plate dampers for seismic response control of piping systems

In a vibrating system, the most effective mechanism to dissipate energy is the inelastic strain of supplemental metallic elements with plastic deforming characteristics. An X-plate damper (XPD) is one device that is capable of sustaining many cycles of stable yielding deformation resulting in a high level of energy dissipation or damping. The present paper focuses on a numerical study to investigate the seismic effectiveness of an XPD for piping systems in industrial units (e.g. chemical and petrochemical industries) and utilities such as thermal and nuclear power plants. The seismic performance of piping systems is investigated under important parametric variations of the damper properties (i.e. height, width and thickness of the XPD) under arbitrary ground motions. Investigations are reported for an industrial piping system equipped with an XPD and the response quantities of interest are the relative displacements, absolute accelerations and support reactions of the piping system. The response quantities of the controlled (with XPD) piping system are compared with the corresponding uncontrolled (without XPD) piping systems, to establish the seismic effectiveness of the XPD. Seismic energy dissipation in the piping system, which is represented by the hysteretic energy of the XPD, is also evaluated and compared. It is observed that the XPDs are very effective in reducing the seismic response of piping systems. Moreover, for a given piping system and ground motion, it is difficult to arrive at the optimum properties of an XPD from the parametric variation of the properties of the XPD and by monitoring the responses of the piping system. Therefore, use of hysteretic energy dissipation by an XPD is proposed to obtain the optimum properties of the XPD. Furthermore, the effects of the properties of an XPD on the free vibration characteristics of the piping system are also presented, which is crucial for the design of piping systems with XPDs.     

压水堆核电厂二回路系统管道热效率的影响因素分析

在压水堆核电厂热经济性分析中,管道热效率的分析往往不被研究者所重视。首先从管道热效率的定义出发,给出了管道热效率的计算表达式,以及各种管道损失的计算方法。然后针对某些影响管道热效率的因素,同时也对蒸汽动力转换系统循环热效率产生影响的问题,分析了影响管道热效率的因素变化对蒸汽动力转换系统循环热效率和压水堆核电厂全厂热效率的影响。最后,以某990MW核电机组为例,通过计算分析了如主蒸汽管道疏水门泄漏蒸汽、厂用蒸汽、主蒸汽管道散热、蒸汽发生器排污等对管道热效率、蒸汽动力转换系统循环热效率及全厂热效率的影响。结果表明,上述因素变化均导致管道热效率降低和全厂热效率的降低,但不同因素变化对全厂热效率的影响机理却存在较大的差别。     

考虑流固耦合的泵站压力管道激振特性有限元分析

为探究大型高扬程泵站压力管道运行时高频激振的诱因和振动特性,以甘肃省景电二期总干七泵#1压力管道为研究对象,采用附加水体质量法建立基于ANSYS有限元的简化流固耦合仿真模型,对压力管道的激振特征进行数值模拟,分析不同机组启闭工况下压力管道的振动模态及位移变形规律,揭示压力管道的主要振动变形特性。结果表明,在多种运行工况下,压力管道弯管段和大小管连接段振动比较明显,且高阶模态的振型振幅高于低阶模态,不易被激振的出水管随着阶次的增高也逐渐产生振动变形。经DASP测试系统现场振动监测表明,数值模拟结果与现场测试结果吻合良好。该结论可为高扬程泵站压力管道避振、减振优化设计提供技术支撑,也为同类泵站工程的更新改造设计和安全运行提供理论依据。     

发动机标定方法及性能预测的研究

电控发动机性能开发是一项系统工程,包括性能设计、结构设计、标定数据优化以及整机性能优化.通过分析电控系统的标定方法、试验设计方法,认为标定方法不仅要做到优化电控系统与发动机的匹配,还应具备预测缺陷、性能和改进方向的功能.