有机热载体锅炉系统管道安全问题初探

通过对一起有机热载体锅炉事故的分析,提出了目前有机热载体锅炉系统管道安全面临的问题.根据相关的规程、标准的要求,结合事故案例,简单列举了有机热载体锅炉系统管道在安装、使用和检验中应注意的问题.     

在用工业管道风险研判方法

借鉴国际管道技术委员会对输气管道提出的失效原因以及RBI思路，利用“专家打分法”对管道安装、维护、保养、检验等各个环节，量化发生事故的可能性和后果的严重程度，从而以半定量法确定在用工业管道风险值，进而进行风险预警，为压力管道使用单位、河北省质监局安全监察工作提出合理化建议。     

注气站气井井口输送管线弯头断裂原因分析

介绍了某天然气注气站气井井口管线变头断裂的情况，并分析了事故发生原因。对新安装的压力管道提出强制检验的建议。     

我国压力管道的运行维护与检验技术研究

按有关规定，我国压力管道分为工业管道、公用管道和长输管道。主要介绍了本专题调研组所了解到的我国压力管道相关运行维护管理与检验现状，重点介绍了新颁布的《在用工业管道定期检验规程》，并提出应加强压力管道检验技术及其应用的研究，特别是埋地管道的检验技术研究。同时，在进行埋地管道检验时，应加强对检验结果的安全性评定。最后，还提出了我国压力管道宜采用的运行维护管理模式与检验措施等。     

工业蒸汽管道减压阀爆炸失效分析

为探究减压阀爆裂事故原因,结合压力管道的设计、安装工况,对事故减压阀进行失效分析,得出事故原因为管道设计不当、安装不规范,阀门材质的选取不符合标准要求等因素所导致。     

在用工业管道全面检验几个问题的探讨

本文结合笔者近期对某化工厂156余条工业金属管道进行的全面检验工作实践，对检验中资料审查、管道级别划分、管道测厚、焊接接头无损检测等检验项目中遇到的具体问题进行了分析。对管道减薄及其安全状况等级评定，焊接接头缺陷及按局部减薄定级的未焊透缺陷的安全状况等级评定进行了汇总。发现安全状况等级4级的缺陷较多，且以原始超标焊接缺陷为主，因此应加强安全评定工作，进一步放宽检验缺陷。同时在以后的管道安全监察工作中，应全面开展并加强管道元件制造和管道安装监督检检工作。     

浅析管道泄漏的原因及对策

鉴于目前我国很大一部分管道使用时间已超过20年,管网进入事故高发期,泄漏爆管事故频频发生.针对管网泄漏的原因进行了研究,认为主要是由外力破坏、管道腐蚀、设计不合理、安装质量及检测验收不合格等原因造成,并对每一项进行了深入分析,在此基础上给出相应解决方法.     

氧气管道设计与安装要点分析

结合氧气输送管道安全事故的成因,就如何加强氧气管道设计、安装,杜绝安全事故展开进一步探讨。重点从管道选材、管道布置、材料检验、施工等多个角度展开论述。     

燃气管道定期检验的必要性探讨

根据部分燃气供应企业市政燃气管道的检验情况,论述了燃气管道定期检验的必要性.监督、检验、主管部门及管道使用企业应重视燃气管道的定期检验,并按规定执行,以便及时发现隐患及实施整改,确保燃气管道的安全运行.     

压力管道单线图的作用

本文从压力管道的施工、使用管理、修理改造、检验检测等环节阐述了压力管道单线图的作用。同时也指出在实际工作当中,我们应当重视单线图的绘制和运用。     

Experimental studies of orifice-induced wall pressure fluctuations and pipe vibration

A hydraulic test for studying orifice-induced random wall pressure fluctuations and vibration in a pipeline is presented. Natural frequencies of the structure, statistical characteristics of the fluctuating pressure and structure acceleration response have been studied. The orifice significantly disturbed the pipe flow and greatly increased the fluctuating pressure level and the dominating energy is concentrated at the lower frequency range. The highest fluctuating pressure level appears at 1.7 diameters downstream of the orifice in the axial direction, while the Power Spectral Density and the root mean square of the pressure fluctuations do not show significant difference in the radial direction. The test results also confirm the weakly coupled fluid-structure system assumption for the test pipe system.     

Reliability-based assessment of polyethylene pipe creep lifetime

Lifetime management of underground pipelines is mandatory for safe hydrocarbon transmission and distribution systems. The use of high-density polyethylene tubes subjected to internal pressure, external loading and environmental variations requires a reliability study in order to define the service limits and the optimal operating conditions. In service, the time-dependent phenomena, especially creep, take place during the pipe lifetime, leading to significant strength reduction. In this work, the reliability-based assessment of pipe lifetime models is carried out, in order to propose a probabilistic methodology for lifetime model selection and to determine the pipe safety levels as well as the most important parameters for pipeline reliability. This study is enhanced by parametric analysis on pipe configuration, gas pressure and operating temperature.     

泵站压力管道振动特性分析及减振优化设计

为探究泵站压力管道的不同布置形式对管道振动的影响,选取宁夏盐环定泵站工程二泵站#1压力管道为研究对象,建立基于流固耦合的泵站压力管道水流ALGOR数值模型,并采用DASP振动测试系统获取振动信号对模拟结果进行验证,分析压力管道水流流态对管道振动的激励特征并提出优化设计方案。结果表明,压力管道进水管处、支管总管相接处及总出水管处均有强烈的振动,但进水管的振动较出水总管振动更为强烈;减振优化设计方案中,调整支管距离对降低水流对管道振动的激励效果微弱,增大管径及改变总管走向对其效果较好,其中总管走向在2°～5°之间较佳,不仅能降低管道振动,而且能减少泵站能耗损失。研究结果可为高扬程泵站压力管道的优化设计提供理论依据。     

输油圆管弯头段泄漏流场数值模拟

目前各国在役管道存在的老化及腐蚀等问题对人民生命财产安全构成了潜在的危害。如何及时准确地检测管道泄漏现象的发生,对管道安全运行及人民群众的生命财产安全具有重要意义.采用有限容积法,建立三维管道泄漏方程,分析了不同输送速度及泄漏孔径对泄漏后管内流场影响。研究发现：输送速度和泄漏孔径对管内压强、局部高压区、泄漏量、泄漏质量百分比的影响相反。管内压强和流量变化特性为高科技管道检测泄漏技术提供了可能性。     

Effects of different loads on structure stress of “L”-type large-diameter buried pipe network based on fluid-structure-heat coupling

Large-diameter buried pipeline is widely used because of its energy-saving advantage and high efficiency. In this paper, “L”-type heat pipe network was taken as the research object, which was studied using the flow–heat–solid coupling method. The ANSYS Workbench platform was used to simulate heat transfer and the flow of the medium in the pipe network. The pressure and temperature of the flow field and the temperature, equivalent stress of the solid structure under different conditions were calculated, and the force characteristics of pipe network and elbow under coupled and non-coupled loads were compared. Results show the maximum equivalent stress was located at inner wall surface of the short-arm anchor end. The equivalent stress of the inner wall was larger than that of the outer wall at the same position. The stress of the straight pipe of the pipe network was mainly affected by the temperature of the fluid, whereas the stress of elbow was mainly affected by the pressure. The stress distribution of the pipe network was influenced by the temperature and pressure loads coupled and the coupling effect was stronger with the higher pressure and temperature of the medium, but the coupling effect had its limit.     

火电厂主要蒸汽管道压降算法研究

为了解决管道压降计算的准确性问题，基于对前苏联、德国、美国的管道压降算法进行比对分析，结合火电厂主要蒸汽管道的特点和性能试验数据，提出了一种优化和精确的蒸汽管道压降的算法。新的算法消除了先前算法由于试验条件、理论计算、制造工艺等的不同对于结果的偏差，对主要蒸汽管道的系统、布置的优化提供了更为有效的途径。     

CFD modeling for slurry flow through a horizontal pipe bend at different Prandtl number

The present work shows the slurry flow characteristics of bottom ash particulates having density 2219 kg/m³ at different Prandtl number through horizontal pipe bend. The simulation is carried out by adopting Eulerian two-phase model in conjunction with RNG k-ε turbulence model using available commercial software ANSYS Fluent. The transportation of solid particulates has the settling behaviour in the slurry pipeline and that leads to the sedimentation and blockage of the pipeline resulting more power and pressure drop in the pipeline. Therefore, it is important to know the transport capability of the solid particulates at different Prandtl fluids to minimise the pressure loss. The fluid properties at four Prandtl numbers i.e., 1.34, 2.14, 3.42 and 5.83 are used to carry the bottom ash concentration ranging from 40 to 60% (by weight) at mean flow-velocity ranging from 1 to 5 ms^?1. The obtained computational results for pressure drop are validated with the published data in the literature and found in good agreement. The findings show that the pressure drop rises with escalation in flow velocity and Prandtl number for chosen efflux concentration range. The bottom ash particulates flowing at higher Prandtl fluid experiences less pressure drop through bend cross section in comparison to bottom ash particulates flowing at low Prandtl fluid. Finally, the contours of granular pressure, granular temperature and wall shear stress are predicted and discussed in details through the bend cross section to understand the complex slurry flow for chosen Prandtl numbers.     

Experimental analysis on the effect of pipe and orifice diameter in inter tank hydrogen transfer

Hydrogen is an energy carrier which can be utilized in many sectors like stationary and transportation energy with nearly zero emission. Hydrogen energy is more efficient when compared to other energy sources. Hydrogen can be a replacement for fossil fuels in future as it emits only water when it is burned. In this work a mathematical model of transfer of hydrogen between two tanks has been developed using MATLAB simulink software version 21. Flow of hydrogen inside the pipe is controlled by orifice and diameter of this orifice and pipe diameter itself has some impact on outcome parameters such as inlet temperature of pipe, outlet temperature of pipe, heat transfer from one tank to other tank and hydrogen gas flow rate. The influence of orifice diameter as well as initial pressures on outcome parameters of hydrogen gas transfer model has analyzed in this work. From the simulation results it is inferred that when one initial pressure kept constant and other initial pressure keep on varying, no change in inlet temperature, decrease in outlet temperature, increase in heat transfer and increase in gas flow rate were observed when orifice diameter increase in size from 2 cm then 4 cm and then 6 cm. The research work has significant guidance for safety and efficient way of transporting hydrogen through pipeline from one tank to other tank.     

某型柴油机高压油管断裂失效分析及改进

为解决某型柴油机高压油管漏油率较高问题,分析故障油管断裂部位、断口形貌特征、金相组织、振动测试结果及受力,确定高压油管断裂的主要原因为墩头及过渡区域设计不合理,导致其疲劳破坏而发生脆性断裂;优化高压油管结构与管型,改进管夹布置方式,增加油管稳定性;改进油管镦头尾部结构,增大锁紧螺母与镦头贴合面装配应力.振动及耐久试验证...     

Two-phase phase distribution in a vertical large diameter pipe

In view of the practical importance of the application of two-phase flow in a large diameter pipe to various fields of engineering, the characteristics and phase distribution patterns of two-phase flow in a vertical large diameter pipe have been experimentally and theoretically studied for various flow conditions. The local measurements for the interfacial parameters (void fraction, Sauter mean diameter and pressure loss) in a vertical upward air-water two-phase flow in a pipe with 0.2 m in inner diameter and 24 m in height have been performed by using the optical probes and differential pressure transducers. The two-phase flow characteristics have been analyzed with experimental data, which shows that the phase distribution patterns in the vertical large diameter pipe can be divided into two basic patterns, namely, wall peak and core peak. With the application of the concept of skewness, the two-phase distribution patterns have been quantitatively distinguished by establishing a phase distribution pattern transition criterion. An empirical relation for the phase distribution transition from wall peak to core peak was fitted by using the phase distribution pattern transition criterion and the present experimental data and verified by other researchers’ experimental data. This study also showed that there existed the flow plugging phenomena in the low region of the test section at high superficial gas velocity conditions in the vertical large diameter pipe.