管道输运高压氢气与天然气的泄漏扩散数值模拟

基于有限体积法,建立了管道运输高压氢气及天然气的泄漏扩散模型,考虑到氢气与天然气的管道泄漏事故危险性不同,进行了数值模拟与对比,得出了管道泄漏后氢气与天然气的不同泄漏扩散特性.结果表明:高压氢气的泄漏扩散形成的危险云团较大而且集中;氢气初始的泄漏速度比天然气大得多,与周围环境达到压力平衡所需时间较天然气短;随着扩散时间的增加,氢气危险气体云团扩散最大高度较天然气增加得快;在近地面区氢气泄漏扩散产生的危险后果较天然气小.     

基于正交试验的埋地输油管泄漏污染物扩散规律数值模拟

针对埋地输油管道泄漏后油品污染物在土壤内的扩散迁移行为,利用计算流体动力学CFD中的多孔介质流动数值模拟方法,分别研究了土壤孔隙率、土壤含水量、油品密度、油品黏度四个因素与泄漏油品纵向扩散深度的关系,结果表明纵向扩散深度与土壤孔隙率、油品密度、油品黏度呈正相关,与土壤含水量呈负相关.针对泄漏油品纵向扩散深度受多种因素耦...     

高含硫天然气管道泄漏扩散数值模拟

天然气在集输过程中,由于管道老化、腐蚀等因素引起的泄漏事故时有发生,其中以小孔径泄漏事故发生概率偏大.本文利用软件对高含硫天然气小孔径泄漏进行数值模拟,模拟结果显示,泄漏气体中甲烷和硫化氢的扩散范围、浓度含量、烟云高度受风速影响明显.高含硫天然气管道小孔径泄漏后,在环境风速8 m/s时,泄漏形成的危险区域沿地面向下风向...     

受限空间内氢气泄漏扩散行为的数值模拟

氢分子是自然界中最小的分子,很容易通过管道接头、阀门等位置发生泄漏。由于氢气的易燃易爆属性,泄漏后形成的可燃气云一旦遇到火源容易演变成事故。因此,对氢气泄漏扩散行为进行研究有助于掌握氢气事故演化发展规律,对于事故预防具有重要意义。针对一个尺寸为0.47 m×0.33 m×0.20 m的立方体空间建立几何模型,采用自主研发的MPPBuoyantEpplFoam求解器对该模型内的氢气泄漏扩散行为进行了数值模拟,获得了氢气泄漏后的氢气浓度分布、扩散速度分布及流动扩散规律,通过与相关文献中的实验结果进行对比,二者吻合较好,初步验证了该求解器多组分扩散功能的准确性。研究结果表明,在受限空间内,氢气泄漏后表现出如下流动扩散规律：1)氢气从模型顶部竖直向下喷入计算域后,在周围静止空气阻滞作用和浮升力作用下,扩散速度迅速减小,流动的动量控制区变短;2)在氢气注入阶段,计算域氢气浓度分布会在浮力作用下呈现明显的分层效应,上部的氢气浓度高,下部的氢气浓度低;3)氢气停止注入后,在分子扩散作用下,计算域上下部氢气浓度差逐渐变小,并最终达到均匀混合。     

油管泄漏的声场特性计算与分析

超声检测是目前采气井管道泄漏检测中比较常用的一种方法.为了提高泄漏检测的准确性,以天然气井油套管为研究对象,建立了管道泄漏的仿真模型,对油管泄漏时的声源特性及声场分布进行了仿真计算,并探究了油管内外压差对声源及声场的影响.结果表明:油管泄漏时的气体流速较大,泄漏声源以四极子声源为主;声源域的声压级在20～60 kHz范...     

天然气管道环境风险影响分析

对某市天然气输气管道工程不同气象、不同源高条件下事故环境风险的影响范围进行预测与分析.采用气体扩散多烟团模式预测天然气管道泄露及火灾事故的影响范围.结果表明：如果发生天然气泄漏、火灾事故,天然气管道泄漏处下风向的污染物危害范围呈圆环分布;各污染物的扩散多以小风1.5 m/s,稳定度为F类条件下的影响范围最大;在一定的风速和稳定度下,事故影响范围随源高的增高而降低.     

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.     

加强管道治漏 增强节水意识

一、给水管道泄漏原因1.室内给水管道漏水或渗水的原因:(1)管道接头因长期锈蚀,螺纹受损,法兰垫失修破损造成漏水;(2)由于室内管道明装,长期受外界环境腐蚀促使个别管段壁厚减薄以致破裂而渗漏;(3)管道附件与管子连接处由于材料的不同发生电化学腐蚀而渗漏;(4)管件丝扣连接未拧紧造成渗漏;(5)管道对焊焊缝处未焊牢或有砂眼而泄漏;(6)天长日久断裂而渗漏等。2.埋地给水管道漏水或渗水原因:(1)接头不严渗漏;(2)外部载荷增加引起局部管道断裂造成渗漏;(3)管道基础下沉而断裂形成泄漏;(4)管道受到地面腐蚀液体浸蚀破坏而渗漏;(5)树本等生物根系日益长大,使管道受外力的作用造成破坏而渗漏;(6)管道本身质量问题形     

锅炉"四管"及热力系统主要承压管道泄漏原因分析与预防

火力发电厂锅炉"四管"及热力系统主要承压管道一旦发生泄漏,只有强迫停炉、停机处理,严重影响火力发电厂安全经济运行,给发电企业造成巨大的经济损失.简要分析了锅炉"四管"及热力系统主要承压管道泄漏原因,并结合华能威海电厂近几年防磨防爆治理的成功经验,提出了防止锅炉"四管"及热力系统主要承压管道泄漏的综合预防措施.     

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。     

Leakage and diffusion behavior of a buried pipeline of hydrogen-blended natural gas

Buried pipelines are one method of conservation transfer for widely used gases such as natural gas and hydrogen. The safety of these pipelines is of great importance because of the potential leakage risks posed by the flammable gas and the special properties of the hydrogen mixture. Estimating the leakage behavior and quantifying the diffusion range outside the pipeline are important but challenging goals due to the hydrogen mixture and presence of soil. This study provides essential information about the diffusion behavior and concentration distribution of underground hydrogen and natural gas mixture leakages. Therefore, a large-scale experimental system was developed to simulate high-pressure leaks of hydrogen mixture natural gas from small holes in three different directions from a pipeline buried in soil. The diffusion of hydrogen-doped natural gas in soil was experimentally measured under different conditions, such as different hydrogen mixture ratios, release pressures, and leakage directions. The experimental results verified the applicability of the gas leakage mass flow model, with an error of 6.85%. When a larger proportion of a single component was present in the hydrogen-doped natural gas, the leakage pressure showed a greater diffusion range. In addition, the diffusion range of hydrogen-doped natural gas in the leakage direction was larger at 3 o'clock than that at 12 o'clock. The hydrogen blend carried methane and diffused, which shortened the methane saturation time. Moreover, a quantitative relationship between the concentration of hydrogen-doped natural gas and the diffusion distance over which the hydrogen-doped natural gas reached the lower limit of the explosion was obtained by quantitative analysis of the experimental data.     

机车管路应用铁基形状记忆管接头的可行性分析

针对内燃机车各系统管路连接产生的“三漏”问题,分析了其产生的原因,且据此提出了采用铁基形状记忆合金管接头取代传统管接头的解决办法,并对这种技术移植的可行性进行了论证。     

The Stability Criterion Model and Stability Analysis of Waxy Crude Oil Pipeline Transportation System Based on Excess Entropy Production

Based on the theory of non-equilibrium thermodynamics, considering the dynamic effect of molecular diffusion and the change in thermodynamic parameters caused by wax precipitation, the phenomenological relations of different thermodynamic “force” and “flow” interactions were derived. The corresponding thermodynamic model of a waxy crude oil pipeline transportation system was built, and then, the excess entropy production expression was proposed. Furthermore, the stability criterion model of the pipeline transportation system was established on the basis of Lyapounov stability theory. Taking the oil pipeline in Daqing oilfield as an example, based on the four parameters of out-station temperature, out-station pressure, flow rate and water content, the stable and unstable regions of the system were divided, and the formation mechanisms of the two different regions were analyzed. The experimental loop device of wax deposition rate was designed, and then, the wax deposition rate under the four parameters was measured. The results showed that the stable region of the wax deposition rate fluctuation was basically in accordance with the stability region analyzed by the criterion model established in this paper, which proved that the stability criterion model was feasible for analyzing the stability of the waxy crude oil pipeline transportation process.     

CO2在盐水层中的扩散和运移泄漏风险评价模型

温室效应和空气污染是21世纪人类面临的严重问题,而CO2埋存是解决温室效应的最有效方法。在CO2地下地质埋存中,盐水层埋存因其地质储量巨大受到了极大关注,同时也存在很多潜在的风险,因此建立CO2注入到盐水层后的扩散运移泄露风险评价模型将为人类安全埋存CO2提供理论支持。首先,考虑到CO2在联通水层中因浓度差泄漏,以菲克定律为理论基础,结合惠尔凯公式,建立了CO2扩散泄漏风险评价模型;其次,考虑到CO2在联通水层中因压力差泄漏,以达西定律为基础,利用气体平面径向稳定渗流公式和垂直管流相关公式等建立了CO2运移泄露风险评价模型;最后,考虑到CO2从盖层逃逸,以毛细管压力为基础建立了CO2通过盖层泄漏风险评价模型。结果表明,扩散系数越大,泄漏时间越短;扩散和运移泄漏时间相差很大,计算运移泄漏时可忽略扩散作用的影响;当埋存的CO2剩余压力小于盖层的突破毛细管压力时,气体以扩散方式泄漏,否则在压力差的作用下以渗流运移方式泄漏。     

原油管道伴热工艺热力分析

根据原油管道伴热方式,建立原油管道伴热系统能量平衡模型,对管道伴热系统进行数值模拟,计算原油和伴热水的沿程温度变化,并对比分析不同伴热方式下的伴热效果,根据管线长度,优化选择伴热方式。     

海底含蜡原油管道停输降温过程的数值模拟

研究海底含蜡原油管道的停输降温过程,对避免＂凝管＂事故的发生起着重要的作用。针对海底含蜡原油管道运行环境的特点,建立海底管道停输时的非稳态传热模型,利用CFD软件模拟海底管道停输过程中温度随时间的变化规律,分析管径、管道周围海泥温度等因素对停输温降的影响,从而确定最佳停输时间,为海底含蜡原油管道制定再启动方案提供理论依据。     

析蜡潜热对架空管道停输介质温度分布影响研究

研究热油管道的停输介质的径向温度场分布,对确定安全停输时间具有重要的指导作用.由于考虑析蜡潜热的影响能更准确的描述热油管道停输介质的温度分布,建立了架空热油管道停输径向传热物理模型和数学模型,并用FLUENT软件模拟了架空管道停输温降过程中径向温度场分布.该方法能够准确模拟原油凝固过程中固液相界面的位置,模拟结果更符合...     

溶剂油管线泄漏原因分析及对策

对泄漏管段取样，进行了宏观、渗透、测厚、硬度测定、铁素体含量测量、磁记忆应力集中检测以及介质成分、能谱、显微组织分析等综合以上技术分析，得出溶剂油管线失效的原因，为杜绝类似事故，提出了建议和改进措施。     

Study on leakage and explosion consequence for hydrogen blended natural gas in urban distribution networks

It appears to be the most economical means of transporting large quantities of hydrogen over great distances by the existing natural gas pipeline network. However, the leakage and diffusion behavior of urban hydrogen blended natural gas and the evolution law of explosion characteristics are still unclear. In this work, a Computational Fluid Dynamics three-dimensional simulation model of semi-confined space in urban streets is developed to study the diffusion process and explosion characteristics of hydrogen-blended natural gas. The influence mechanism of hydrogen blending ratio and ambient wind speed on the consequences of explosion accident is analyzed. And the dangerous area with different environmental wind effects is determined through comparative analysis based on the most dangerous scenarios. Results indicate that the traffic flow changes the diffusion path of the jet, the flammable gas cloud forms a complex profile in many obstacles, high congestion level lead to more serious explosion accidents. Wind effect keeps the flammable gas cloud near the vehicle flow, the narrow gaps between the vehicles aggravate the expansion of the flammable gas cloud. When the wind direction is consistent with the leakage direction, hydrogen blended natural gas is gathered in the recirculation zone due to the vortex effect, which results in more serious accident consequences. With the increase in hydrogen blending ratio, the higher content of H and OH in the gas mixture significantly increases the premixed burning rate, the maximum overpressure rises rapidly when the hydrogen blend level increases beyond 40%. The results can provide a basis for construction safety design, risk assessment of leakage and explosion hazards, and emergency response in hydrogen blended natural gas distribution systems.