Why is it necessary to control CL in new hydrogen and feed oil?
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The HCl generated by the hydrogenation of CL in the raw materials can cause problems in the operation of the process; under high temperatures, it reacts with Fe and Ni present in the materials of containers or pipelines, leading to corrosion. In the presence of CL, 18-8 austenitic stainless steel is particularly sensitive to pitting corrosion. Pitting corrosion is very dangerous in production; it develops rapidly over a certain area and penetrates deeper, resulting in equipment damage due to localized destruction or leakage as a result of perforations in specific areas. At the same time, HCL reacts with NH in the system to form ammonium salts, which precipitate at temperatures below 350°C and thus block the system (significant precipitation generally begins at 180–200°C).
Chloride corrosion and ammonium salt crystallization are indeed common problems in refineries; the water injection points and electrodialysis optimization mentioned above are very practical! Two additional details are provided for discussion: 1) Our equipment has shown that when the chlorine content in the raw material exceeds 3 ppm, the corrosion rate in the top section of the distillation tower increases significantly; it is recommended to adjust the water injection volume dynamically based on online corrosion monitoring data ； 2) For systems already clogged with ammonium salts, it is possible to try raising the water injection temperature to over 200°C for flushing in the short term, but care must be taken to control the flow rate to avoid erosion. The specific operating parameters still need to be adjusted according to the actual operating conditions of the device~