Corrosion issues in SED aromatic extraction

Has some oxygen entered the system, reacting with sulfolane to produce a highly corrosive substance?

This post was last edited by chentao1985 on 2015-8-19 at 12:02. Our installation has encountered the same issue; it starts with the solvent regeneration tower, and the corrosion is caused mainly by sulfonic acids, chloride ions, and high temperatures in the system. Replace the tube bundles with materials that offer better corrosion resistance. In the solvent regeneration tower, it is necessary to control the bottom temperature properly; the upstream reforming unit should manage the operation of the liquid-phase dechlorination tank carefully. If the chlorine content is not up to standard, the dechlorinating agent should be replaced promptly. The extraction system must properly control the bottom temperatures of each tower, and it is necessary to ensure that the nitrogen seal in the feed buffer tank is functioning correctly. The best method for removing chloride ions from the system is to use the degraded sulfolane regeneration unit from the China Institute of Rock and Mineral Sciences.

I completely agree with your view. Could you please elaborate on the sulfolane regeneration unit at the Institute of Rock and Mineral Sciences? Is it an anion exchange resin?

I’m very sorry; my file was lost and I can’t send it to you. Please forgive me. You can check it online

Just contact the Institute of Geology and Mineral Resources and ask; that’s how you’ll find out. No one here knows more accurately than they do. They also offer another service: you don’t need to purchase the kind of recycling equipment you mentioned. There are specialized companies that handle this; they have the necessary equipment, recycle the materials for you, charge you for their services, and then leave – they only sell their services.

They offer a service that involves on-site processing online, and the results of that processing are quite good. It is necessary to control the negative pressure, as well as the chloride and sulfur content in the upstream raw materials.

Corrosion has occurred, most likely due to oxygen entering the system. It is recommended to pay close attention to the negative-pressure airtight operation during regeneration.

Chloride ions (raw material, circulating water), oxygen (in the negative pressure tower); the system needs to be airtight, and the temperature of the heating steam should be below 210. As for the corrosion rate you mentioned, it seems that oxygen and temperature are the key factors at play. My humble opinion

It seems this problem has occurred in many aromatic extraction processes

It is recommended that your plant keep the temperature of all steam entering the reboiler in the extraction unit at 204°C. Strictly control the pH value of the solvent within a certain range, around 5.5 to 6.5. Increase the processing capacity of the solvent regeneration tower; determine how well the vacuum at the top of the solvent recovery tower is controlled. If a gas extractor needs to be operated during normal operations, it is possible that there is a leak in the solvent recovery tower section. One aspect is the upstream section: it is necessary to check whether the upstream reforming unit employs liquid dechlorination. One should not always look for reasons within one’s own unit; sometimes, it is not possible to determine the content of acidic substances in the extraction feed. One factor is the quality of the solvent; the interval between discharges of aged solvent should be shortened, and the amount of aged solvent discharged increased. To avoid an increase in acidic substances, MEA can be added appropriately. However, an increase in the amount of MEA added leads to severe salt deposition in the extraction tower. The quality of the water in the extraction unit also needs to be carefully controlled, with the water in the system being replaced regularly.