The causes of copper sheet corrosion mainly come from the following three aspects.
1, the analysis of whether the operation is standardized: analysis of the test tubes used in the process of operation, measuring instruments, containers are not clean, sampling is not discharged clean, oil resting time is not enough, poor filtration, as well as the copper sheet production process is not standardized, etc., will cause the corrosion of copper sheet failed. The solution is to standardize the operation of the analysis process.
2, whether it contains corrosive impurities: corrosive impurities generally refers to the sample in the refining process entrained water, alkali or other polar solvents. This type of corrosion is generally due to the refining process section emulsification or settling tank settling time is not enough to cause. Generally manifested as: fraction outlet corrosion failed, while the finished tank sampling corrosion reduced or become better. The solution is to improve the reaction conditions to reduce emulsification, or increase the settling separation time.
3, oil refining whether: the removal of acidic compounds is an important purpose of oil refining, copper corrosion is the degree of acidic compounds removed from the control index.
Acidic compounds in gasoline or liquefied gas basically have two types of acidic oxides and active sulfides. Active sulfides include elemental sulfur, hydrogen sulfide and mercaptan, thiophenol (collectively referred to as thiol sulfur).
Acid oxides and hydrogen sulfide are more acidic and both are easily removed from the oil by alkaline washing. In contrast, mercaptan sulfur is less acidic, and relying on alkali washing alone to remove mercaptan requires a large amount of lye, generating a large amount of malodorous alkali residue, and generally converting mercaptan to disulfide through a catalytic oxidation process. Elemental sulfur at room temperature neither reacts with alkali nor with acid, it is difficult to get rid of from the oil, so most of the causes of oil copper corrosion are caused by elemental sulfur. Elemental sulfur alone, only 0.34ppm can cause obvious gray-black corrosion.
Elemental sulfur sources have two aspects, one is the crude oil itself with, this situation is generally rare; the second is the hydrogen sulfide in the desulfurization alcohol process this weak oxidation environment, which is the main reason for the formation of elemental sulfur corrosion.
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