Patent ID: 7028995

Claim:
A mass transfer column comprising: an external shell defining an open internal region; a plurality of return contact trays and centrifugal contact trays positioned in an alternating and vertically spaced apart relationship within the open internal region, wherein each said return contact tray comprises a tray deck having at least one opening for removing liquid from an upper surface of said return tray deck and a plurality of vapor passages for allowing vapor to flow upwardly through said return tray deck to interact with liquid on said upper surface of said return tray deck, wherein each said centrifugal contact tray comprises a tray deck having an upper surface, a periphery and a plurality of vapor passages for allowing vapor to flow upwardly through said centrifugal tray deck to interact with liquid on said upper surface of said centrifugal tray deck; at least one center downcomer extending downwardly at said opening in said return tray deck, said center downcomer having a lower discharge outlet spaced above said centrifugal contact tray deck for feeding said liquid onto said centrifugal contact tray deck; and at least one annular downcomer extending downwardly at said periphery of said centrifugal contact tray deck and having a lower discharge outlet spaced above said return tray deck for feeding said liquid onto said return tray deck, wherein at least one of said centrifugal contact trays is positioned a greater distance above an adjacent one of said return contact trays than a distance at least one of said return contact trays is positioned above an adjacent one of said centrifugal contact trays.