环氧乙烷装置T形三通管件故障原因分析与改进  

Cause analysis and improvement of T-shaped tee fittings in ethylene oxide plant

作　　者：亢嘉妮 何立东[1] 范文强 杨扬 KANG Jiani;HE Lidong;FAN Wenqiang;YANG Yang(Engineering Research Center of Chemical Safety Education Department,Beijing University of Chemical Technology,Beijing 100029,China)

机构地区：[1]北京化工大学化工安全教育部工程研究中心,北京100029

出　　处：《化工进展》2021年第S01期32-42,共11页Chemical Industry and Engineering Progress

基　　金：2015年北京市共建-科研与研究生培养项目。

摘　　要：环氧乙烷(EO)是重要的石化产品,该产品易燃易爆,同时也是一种有毒的致癌物质。山东某化工厂EO生产装置T形三通管件材料与焊缝质量合格、管内介质无腐蚀性,但是频繁出现裂纹故障导致介质泄漏。T形三通裂纹故障原因不明导致该厂几乎半年更换一次T形三通管件,造成了严重的经济损失。为了解决该厂T形三通频繁失效问题,必须准确查明T形三通故障原因,分析T形三通故障机理成为解决问题的关键。本文运用流场分析软件,结合T形三通管线现场故障情况,分析该厂T形三通内部流场特性及故障机理:T形三通管件内部流场存在两个对称的漩涡,导致T形三通流场速度、压力分布不稳定,形成了大范围低于汽化压力的低压区,液体汽化形成了大量气泡,气泡在三通内壁破裂产生巨大的压力冲击,导致汽蚀破坏,使贫水管线T形三通产生裂纹。基于T形三通故障机理,本文提出了3种改进建议,使用Y形三通、圆弧形三通和球形三通3种三通结构代替T形三通结构,并分析这3种三通结构流场特性。数值计算结果表明:提出的3种三通结构能减小三通管件汽蚀破坏,其中Y形三通有微弱的流体漩涡产生,产生低压区体积最小,但管道入口方向需要改变;圆弧形三通结构不改变原来入口方向,流场压力、速度分布更稳定;球形三通流场绝对压力高于Y形和圆弧形,其结构出口及下游流场压力最稳定。本文为解决T形三通裂纹故障提供了新思路,为保障化工厂三通管件的安全提供了技术支撑。Ethylene oxide(EO)is an important petrochemical product.This product is flammable and explosive,and it is also a toxic carcinogen.In Shandong province,a chemical plant's EO production equipment has qualified T-shaped piping materials and welds,and the medium in the pipe is non-corrosive,but frequent cracks cause the medium to leak.The reason for the failure of the T-shaped tee crack is unknown,causing the plant to replace the T-shaped tee almost every six months pipe fittings caused serious economic losses to the plant.In order to solve the frequently failure of the T-shaped tee at the plant,the cause of the T-shaped tee failure must be accurately identified.Therefore,identifying the failure mechanism of the T-shaped tee becomes the key to solving the problem.This paper uses flow field analysis software,combined with the on-site fault condition of the three-way pipeline,to analyze the internal flow field characteristics and the failure mechanism of the T-shaped three-way device.There are two symmetrical vortices in the internal flow field of the T-shaped three-way device,which results in unstable flow velocity and pressure distribution of the T-shaped three-way flow field.A low-pressure zone with a large range below the vaporization pressure is formed.The liquid vaporizes to form a large number of bubbles,and the bubbles rupture on the inner wall of the tee creates a huge pressure shock,causing cavitation corrosion and damage,and causing the T-shaped tee of the lean water pipeline to crack.Therefore,three improvement schemes are proposed,use Y-shaped tee,arc tee and arc-shaped shaped tee structure instead of T-shaped tee structure,and analyze the flow field characteristics of three tee structures.Numerical calculation results show that the proposed three-way structure can greatly reduce the cavitation damage of the three-way pipe.Among them,the Y-shaped tee has a weak fluid vortex,which produces the smallest volume in the low pressure zone,but the inlet direction changes,not easy to transform;The arc-shaped three

关 键 词：裂纹 三通管件 计算流体力学 汽化 汽蚀 

分 类 号：TQ022.1[化学工程] TQ206