Tray type

[BZLAM21]

Hi dears;
Hope you doing well,Just need a distillation expert to explain this configuration.[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1653385472/tips/Nouveau_Document_Microsoft_Word_utob76.docx[/url]
According to the process datasheet,trays are valve trays type and one pass in this area
and according to the PID the return of the reflux is carried out above the first tray and the temperature control is carried out by a temperature controller in cascade with a flow controller
my question is ; why there is no down comer in the trays number 4 and 5 and what is the relationship with the temperature of the cold reflux and when do we use Center Downcomer or Side Downcomer.
Best regards.

 

[georgeverghese]

If there is no downcomer on tray 4 to tray 5, there should be a total liquid side draw out of this main column to a side stripper, and there should be a return from the bottom of the side stripper to feed tray 5. But your diagram shows no details on side draws/side feeds.
Centre downcomer would be used in 2pass trays.