| 环氧乙烷装置T形三通管件故障原因分析与改进 |
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| 引用本文： | 亢嘉妮,何立东,范文强,杨扬. 环氧乙烷装置T形三通管件故障原因分析与改进[J]. 化工进展, 2021, 40(Z1): 32-42. DOI: 10.16085/j.issn.1000-6613.2019-2024 |
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| 作者姓名： | 亢嘉妮 何立东 范文强 杨扬 |
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| 作者单位： | 北京化工大学化工安全教育部工程研究中心，北京 100029 |
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| 基金项目： | 2015年北京市共建-科研与研究生培养项目 |
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| 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。
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| 关 键 词： | 裂纹 三通管件 计算流体力学 汽化 汽蚀 |
| 收稿时间： | 2019-12-18 |
Cause analysis and improvement of T-shaped tee fittings in ethylene oxide plant |
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| KANG Jiani,HE Lidong,FAN Wenqiang,YANG Yang. Cause analysis and improvement of T-shaped tee fittings in ethylene oxide plant[J]. Chemical Industry and Engineering Progress, 2021, 40(Z1): 32-42. DOI: 10.16085/j.issn.1000-6613.2019-2024 |
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| Authors: | KANG Jiani HE Lidong FAN Wenqiang YANG Yang |
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| Affiliation: | Engineering Research Center of Chemical Safety Education Department, Beijing University of Chemical Technology, Beijing 100029, China |
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| Abstract: | 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-way structure does not change the original inlet direction, the flow field pressure and velocity distribution are more stable, and the flow field characteristics are better than the Y-shaped three-way; Although the absolute pressure of the spherical three-way flow field is higher than that of the Y-shaped and the arc-shaped shaped, the structural outlet and the downstream flow field pressure are the most stable. This article provides a new idea for solving T-shaped tee crack failure and provides guarantee for the safe and effective operation of tee fittings in chemical plants. |
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| Keywords: | crack tee-fitting computational fluid dynamics(CFD) vaporization cavitation |
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