I would like to know why there are two feed inlets in a Sour Water Stripping tower, but normally only one will be in use and the other will be blinded. In Sour water strippers why is chimney tray provided?
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08/09/2010
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MINNI UNIYAL, FLUOR DANIEL INDIA PVT LTD, MINNI.UNIYAL@FLUOR.COM
I am not aware of all strippers, but the one on which I worked recently was having a single feed inlet.
Chimney tray is provided to carry off two different unit operations in a single tower.In case of a sour water stripper, the top portion of chimney tray aids in stripping operation i.e. removal of sour gases from the incoming sour streams.Bottom of chimney tray helps in reboiling a side stream and returning the vapor and liquid streams back to the bottom section.
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08/09/2010
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Egbert van Hoorn, Hocon B V, Egbertvh@hotmail.com
Could you describe the two feed points?
Normally a sour water stripper has only one feed inlet. Maximum stripping is almost always a preferred solution for the environment.
The chimney tray is perhaps part of a draw-off tray for the pump-around cooling in the top. Perhaps here as well a few more details could be helpful.
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08/09/2010
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Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
My description of pump-up vs. pump-down needs clarification. If there is a top pumparound in lieu of overhead condensing, the pumparound must be the pump-up design. otherwise there would be no liquid on the chimney tray on which the pump takes suction. It could , however, be both pump-up and pump-down, with a chimney tray. The advantage over a regular tray is the ability to measure or control the liquid flow to the section below. If there is an overhead condensing system, and a pumparound below that level, it can be either pump-up or pump-down. If it is the latter, a chimney tray is preferred for the reason given. Avoiding an overhead condensing system in this service removes a source of serious corrosion.
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07/09/2010
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Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
For the chimney tray question: If you have a top pumparound in lieu of an overhead condensing system, and if the pumparound is a “pump-down” design, rather than a “pump-up” design, then a chimney tray (total trap-out) would commonly be used there.
Multiple feed nozzles: Those not in use are normally not blinded. They can be switched while running. The reason for multiple feed nozzles include the following:
• Flexibility in periodic changes in feed composition
• Uncertainty in design methods or data used
• Realizing that, although designs are based on steady-state information, plant operation is not steady-state.
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