Vapor-liquid contacting apparatus and process with downcomer at shell

An apparatus for performing vapor-liquid contacting, comprising:

• a plurality of stages disposed in a vessel having a shell, each stage having a contact module and a deck having a plurality of perforations;
• a first contact module comprising a first downcomer with an outer wall and an outlet proximate to a contacting volume, the first downcomer adjacent to the shell;
• a demister having an inlet surface proximate to the contacting volume and an outlet surface superior to the deck such that all of the liquid from the demister will fall onto the deck, wherein vapor which passes through the deck contacts the liquid from the demister, such that the vapor which passes through the demister contacts liquid twice in the same stage, wherein the first portion of vapor is prohibited from flowing up passed the deck through the perforations and wherein the second portion of vapor is prohibited from flowing up passed the deck through the demister;
• and,
• a second contact module below the first contact module, the second contact module comprising a downcomer, wherein the deck extends from the demister to the downcomer of the second contact module, and
• wherein the second contact module is offset horizontally relative to the first contact module.

An apparatus for performing vapor-liquid contacting, comprising:

• a vessel comprising a shell;
• a first contact module comprising a downcomer, said downcomer comprising an inner wall and an outer wall, the downcomer adjacent to said shell of the vessel and comprising an outlet proximate to a contacting volume;
• a demister having an inlet surface proximate to the contacting volume such that the contacting volume is between the outlet of the downcomer and the inlet surface of the demister;
• a deck inferior to an outlet of the demister, the deck having a plurality of perforations, and a further deck superior to the outlet of the demister and having a plurality of perforations, the further deck attached to the downcomer;
• and
• a weir adjacent to the downcomer extending above a base of the further deck for holding up liquid on the further deck,
• wherein only a first portion of vapor flows up passed the deck through the demister and a second portion of vapor flows up passed the deck through the perforations, wherein the first portion of vapor is prevented from flowing up passed the deck through the perforations and the second portion of vapor is prevented from flowing up passed the deck through the demister.