油气处理厂原料气分水器腐蚀分析

Corrosion Analysis of Water Separators of Feed Gas in Oil/gas Processing Plant

某油气处理厂的原料气中含有CO2,其降温过程中会产生大量游离水,因此与碳钢接触时就会产生腐蚀。原料气在高速流动中不断冲刷变径、弯头处的腐蚀产物膜,不断形成新的腐蚀。分水器入口存在异种金属相连的情况,其接触位置存在电解质时会发生电偶腐蚀。分析认为,CO2腐蚀是造成分水器腐蚀的主要原因,异种金属直接接触、流体高速冲刷辅助加剧了腐蚀。为了避免原料气对分水器的腐蚀,应尽量脱除其中的游离水,或者选择耐腐蚀性能更好的材质;同一个工艺系统应统一管材,或者尽量避免电位差较大的异种金属直接接触。

Since the feed gas contains CO2 and plenty of free water generates during the temperature declining process, the carbon steel is corroded when contacts the feed gas. The feed gas constantly washes the corrosion product film on the elbow pipe and causes new corrosion. Galvanic corrosion occurs on the entrance of the water separators because of the direct contact of dissimilar metals. Based on the analysis, the CO2 is the main reason of the corrosion of water separators while the direct contact of dissimilar metals and the scour from the feed gas accelerates the corrosion. To avoid the corrosion, it is necessary to eliminate the free water or utilize the materials with better corrosion resistance. Meanwhile, only one certain kind of material should be used in a process system to avoid the direct contact of dissimilar metals.