Abstract:

Air coolers are important heat exchange equipment in the hydrogenation process. The problem of service time far lower than the design life due to corrosion and leakage of tube bundles is common, and its failure mechanism needs to be further explored. A multiphase flow numerical simulation was carried out to investigate the corrosion and leakage of tube bundles in the top air cooler of a fractionation tower in a petrochemical plant. The results show that the complex flow field distribution is the main cause of leakage in air cooler tube bundles. Specifically, the presence of vortices inside the tube box results in varying velocities, fluid-wall impact angles, and gas-liquid two phase distributions within the tube bundle, which is an important reason leading to the uneven distribution of the leaking tube bundle of the air cooler. The actual leakage tube bundle as an example of corrosion analysis, the results show that the impact angle and liquid phase distribution is the key factor affecting the erosion-corrosion, and gas-liquid two-phase erosion-corrosion is the root cause of the leakage of the tube bundle. Finally, the erosion-corrosion mechanism of the air cooler is proposed from the perspective of multiphase flow according to the research results.

Key words: gas-liquid two-phase flow, flow field, mass transfer, corrosion, computational fluid dynamics

摘要：

空冷器是加氢过程的重要换热设备，因管束腐蚀泄漏导致在役时间远低于设计寿命的问题普遍存在，其失效机理需要深入探究。针对某石化厂分馏塔顶空冷器管束腐蚀泄漏问题进行了CFD模拟研究。结果表明，复杂的流场分布是导致空冷器管束冲刷腐蚀泄漏的主要原因。具体来说，管箱内部旋涡的存在使得管束内流体的速度，流体与壁面的冲击角度，以及气液两相分布情况各异，这是导致空冷器泄漏管束分布不均的重要原因。以实际泄漏管束为例进行了腐蚀分析，结果表明冲击角度以及液相分布是影响空冷器冲刷腐蚀的关键因素，气液两相冲刷腐蚀是导致管束泄漏的根本原因。最后根据研究结果从多相流动的角度提出了空冷器冲刷腐蚀机理。

关键词: 气液两相流, 流场, 传质, 腐蚀, 计算流体力学