Question: What is the maximum concentration of chloride ions in decarburized MDEA?
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The company currently has a natural gas hydrogen production facility that uses MDEA for solvent decarburization. Due to corrosion and leakage in the carbon steel tubes of the semi-poor liquid cooler, a small amount of circulating water has leaked into the MDEA, resulting in a chloride ion concentration of around 150 mg/l. System equipment, pipes, and valves are generally made of 304 stainless steel or have a stainless steel lining. Question: What is the maximum allowable concentration of chloride ions in decarbonized MDEA?
If following the requirements for the pressure testing medium specified in GB150, for austenitic stainless steel containers, the chloride content in water should not exceed 25 mg/L； The MDEA amine solution system, particularly the system in which CO2 is absorbed in the rich solution, exhibits a high tendency to corrode. Moreover, 304 is the worst type of stainless steel, so its tolerance limit for chloride ions should be much lower than 25 mg/L.
BASF recommends that the chloride ion content should be less than 100PPM
Yes, your answer is correct. From a metallurgical and physical perspective, BASF requires stainless steel to have levels of <100 ppmw and carbon steel to have levels of <300 ppmw in the amine solution system. However, for the solutions used by BASF for deacidification, materials of at least SS316 or higher are recommended; abroad, 304 material is generally not used in amine solution systems, as its properties after welding do not fully meet the requirements. Therefore, for 304 material, it is safer to set a lower limit for the chloride ion content