Service life of 316L distillation column
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Our plant’s fractionation tower uses 316L material, and it has been in use for 5 years now. It was found that the dry point of the three-blend oil is 320–330 degrees, and the flow rate at 300°C is 90%. It is suspected that the trays below the three-phase oil side stream in the fractionation tower have suffered corrosion and perforation. I would like to ask fellow sailors for their help in analyzing this.
You’re right; it’s very likely that the tray has corroded and perforated. The material for the tower internals should preferably be Mo4.5Cu.
At this temperature, for tower internals made of 316L material, suppliers can generally only guarantee a service life of 3 years; since you have used them for 5 years, it should be time for them to reach the end of their useful life. If you plan to park it, it’s best to place an order in advance. Also, I personally don’t think it’s necessary to use higher-quality materials, as the useful life of your tower will have expired after another 5 years.
Generally, if the trays are corroded, the pressure difference at the top and bottom of the tower will decrease significantly. You can compare the pressure drop under normal operating conditions before and after to see the difference.
Compare with previous operation data to see if there are any changes. If the tray is corroded, the operating data will definitely change
316L can certainly be used at temperatures over 300 degrees, and a usage period of 5 years is not very long; corrosion within the distillation tower should also not occur rapidly. I believe that the reason for the changes in the data lies in the low likelihood of plate corrosion and a higher likelihood of blockages. Corrosion and perforation lead to a decrease in pressure drop, while blockages result in an increase in pressure drop. It’s been 5 years – was no maintenance inspection carried out during that time? It’s time to conduct inspections and cleanings.