Corrosion-free pipelines for sulfur-containing crude oil
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I am working on a CPF project in the Middle East, where the sulfur content is 2–3 g/L; it is sour crude oil. However, from the oil wells to the CPF crude oil processing stage, the oil, gas, and water separation systems show no signs of corrosion, whereas corrosion is quite severe in the LPG gas processing area. The question now is why, with such a high sulfur content, there is no apparent corrosion in the pipelines of the oil treatment system What is the reason for this?
The temperature for separating oil, gas, and water is generally below 80 degrees; there is no gas-liquid phase change, and corrosion is minimal. In the gas processing area, there is a process from the liquid phase to the gas phase; this represents typical wet hydrogen sulfide corrosion. Moreover, some chlorides decompose, and chloride ions play a role in the corrosion process, which is why the corrosion is severe.
In the oil zone, separation of oil, gas, and water is achieved, as well as gas-liquid phases； The separated gas enters the LPG unit, where it undergoes a process of converting moisture into dry gas, as well as processes of desulfurization, dehydration, and dehydrocarbonation. In the crude oil separation unit for separating oil, gas, water, and LPG (converting wet gas to dry gas), what are the differences between the liquid phase and the gas phase?
Crude oil contains only elemental sulfur, and salts do not decompose either; therefore, corrosion is minimal, or it is practically undetectable. During the later gas processing stage, as the temperature rises, elemental sulfur and salts begin to decompose into hydrogen sulfide and chloride ions, which is the cause of increased corrosion.