Has anyone out there ever observed a distillation tower having a collapsed or fouled sieve tray(s). If so what are the characteristic(s) of each scenario?
Hello All, I thank you very much for the replies. Let me describe this particular tower; This tower is a Debutanizer for Alkylation Unit. Alkylate at the bottom and Normal Butane at the top, without side draw. This tower is currently in operation. Before the upset, reflux rate was >500 bph, now we have <250 bph and greatly affecting our bottom temp. What I'm asking is for folks who has experience any tower tray failures i.e. collapse trays etc. what are delta T and or delta P that was noticed. Thank you.
Good nigth gentlemen. Thank you for inviting me to participate in this analysis. It will be very interesting for me to help you to solve your problem. Of course I would like to have more data as the exact composition of feed, bottom and top column and operating conditions as to simulate the distillation column but only to illustrate the problem.
Concretely, I think that your column is almost at flooding condition because you are not able to increase the reflux and if you try to do that pressure and temperature at bottom increases.
All the distillation columns have many analysis points in its body, as to take samples at least every two trays. It is also possible to check the pressure after or before to take the samples.
With pressure data the process engineer should make a graphic from bottom to top as to detect exactly the flooding area which is showed as the point when an abrupt change of pressure occurred.
The cause of flooding is because part of the tray holed area is plugged sometimes for the polymerization of some alkylation products due to temperatures or not programmed shut-down.
This is why all the column conditions have changed and is very difficult to get top product in specifications.
Unfortunatelly, you must shut down the column as to inspect all the trays after a steaming procedure.
what we discovered was foulng of trays which led us to chemically clean the fractionating column from top to bottom. We are currently back into normal mode. I thank you for your recommendations
Sometime presence of water as a component is very dangerous but when the distillation column is out of service it is condensed and trapped in weirs and of course at bottom. When the operator starts up the column putting steam to the reboiler without watching temperature and pressures in all of a sudden the water flashes and blows up the tray sieve.
This situation can be present after washing the column with water as to eliminate some solids set in trays.
Petroleum Refinery Distillation Column
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