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Are there approaches/techniques/instrumentation to gauge if you have fouling occurring (from salt deposition) in top trays on crude unit? One can measure top section tray DP, however, the DP may take time to build up. Are there other things besides DP that may give you quicker response on fouling taking place in top trays of crude tower?
 
Answers
11/08/2015 A: Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
One can monitor the heat duty of TPA exchangers. Normally the Crude column top section tray fouling shows up in this section and reduces heat recovery from TPA.
06/04/2015 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
You could try installing a corrosion probe that is designed to be just above a tray deck where you suspect fouling. The amount of corrosion should be related to that amount of fouling going on. Whether it works or not will depend on whether you get the probe in the right spot. You could also try an external corrosion sensor such as permasense. Whether that is effective will depend largely are the type of salts being formed and where you locate the sensors.
The best approach is do salt point calculations. If the fouling material is ammonium chloride, the salt point can be monitored with a simple spreadsheet. If it is an amine salt more complex ionic modelling may need to be done. By comparing the calculated salt point with the actual overhead temperature you can tell when you are increasing your risk of fouling. If your fouling is coming from salts being returned to the tower via wet reflux, this approach will not work.
If you need help figuring out what is going on or figuring out the best approach for monitoring your system, I may be able to help you. I have done quite a bit of this sort of thing in the past.