Abstract:

Inspection of long-term operating atmospheric and vacuum distillation units reveals that non-uniform thinning frequently occurs in the outlet pipeline of the atmospheric tower overhead air cooler, with local thinning rates exceeding 30%. The risk of pipeline perforation and rupture increased significantly, which could easily cause overhead oil and gas leakage. Analyses were carried out from some dimensions including pipeline material, operating condition and process anticorrosion technology. The results show that pipeline wall thinning primarily originates from erosion corrosion induced by gas-liquid two-phase flow, as well as under-deposit corrosion resulting from ammonium salt crystal deposition in the low-temperature zone at the atmospheric tower overhead. In response to this problem, a series of anti-corrosion optimization plans were proposed, including improving pipeline materials, introducing ultrasonic-electric desalination synergistic demulsification technology, strengthening crude oil demulsification to reduce the amount of chloride ions carried, expanding overhead water injection volume, and adding online desalination facilities. Relevant measures can effectively mitigate the corrosion rate of the tower overhead system, extend the service life of the equipment, and provide technical support for the safe, stable, and long-term operation of atmospheric and vacuum distillation unit.

Key words: Atmospheric and vacuum distillation unit, Overhead air cooler, Corrosion, Analysis, Causes, Measures

摘要：

对长周期运行的常减压装置进行检测发现，常压塔顶空冷器出口管线易出现非均匀减薄现象，局部减薄率超30%，管线穿孔、破裂的风险显著上升，易引发塔顶油气泄漏。因此，从管线材料、运行工况、工艺防腐等维度进行了分析。结果表明，管线减薄主要由气液两相流的冲刷腐蚀和常压塔顶低温区铵盐结晶沉积引发的垢下腐蚀造成。针对该问题，提出了改进管线材料、引入超声波-电脱盐协同破乳技术、强化原油破乳以降低Cl^-携带量、扩大塔顶注水量、新增在线除盐设施等一系列防腐优化方案。相关措施可有效减缓塔顶系统的腐蚀速率，延长设备服役周期，为常减压装置的安全、稳定、长周期运行提供技术支撑。

关键词: 常减压装置, 常顶空冷器, 腐蚀, 分析, 原因, 措施