Membrane sweep with internal reheat of sweep gas

Patent metadata

Field	Value
Publication number	US-12296295-B2
Application number	US-202217978742-A
Country	US
Kind code	B2
Filing date	Nov 1, 2022
Priority date	Nov 1, 2022
Publication date	May 13, 2025
Grant date	May 13, 2025

Abstract

Internally reheated sweep gas-aided membrane gas separation module in which the sweep gas is expanded retentate that is warmed through heat exchange with non-expanded retentate within the module.

First claim

What is claimed is:

1. A double-ended, counter-flow gas separation membrane module with internally reheated sweep gas, comprising:
a tubular pressure vessel having a feed gas inlet and a retentate gas outlet formed therein;
a left side end cap sealing a left side end of the tubular pressure vessel and comprising a left side permeate outlet;
a right side end cap sealing a right side of the tubular pressure vessel and comprising a right side permeate outlet;
a first membrane element concentrically disposed concentrically within the tubular pressure vessel and comprising:
a first end facing a middle of the tubular pressure vessel;
a second end facing the left side of the tubular pressure vessel;
a plurality of hollow fiber membranes arranged around a hollow porous center tube having a first end facing the middle of the tubular pressure vessel and a second plugged end;
a permeate tube concentrically disposed within the hollow porous center tube of the first membrane element;
a nub, made of a polymeric material, formed around the first end of the first membrane element, wherein ends of the plurality of hollow fiber membranes of the first membrane element adjacent the nub thereof fluidly communicate in gas-tight fashion with an interior of the permeate tube of the first membrane element;
an annular cap sealed against an inwardly-facing face of the nub of the first membrane element that is adjacent the middle of the pressure vessel such that a permeate collection space is defined therebetween and which open bores of the plurality of hollow fiber membranes of the first membrane element fluidly communicate therewith; and
a tubesheet made of a polymeric material that is formed around the second end of the first membrane element, wherein open bores of the plurality of hollow fiber membranes at ends thereof that are adjacent the second end of the first membrane element are plugged by the polymeric material of the tubesheet;

a second membrane element concentrically disposed concentrically within the tubular pressure vessel and comprising:
a first end facing the middle of the tubular pressure vessel;
a second end facing the right side of the tubular pressure vessel;
a plurality of hollow fiber membranes arranged around a hollow porous center tube having a first end facing a middle of the tubular pressure vessel and a second plugged end;
a permeate tube concentrically disposed within the hollow porous center tube of the second membrane element;
a nub, made of a polymeric material, formed around the first end of the second membrane element, wherein ends of the plurality of hollow fiber membranes of the second membrane element adjacent the nub thereof fluidly communicate in gas-tight fashion with an interior of the permeate tube of the second membrane element;
an annular cap sealed against an inwardly-facing face of the nub of the second membrane element that is adjacent the middle of the pressure vessel such that a permeate collection space is defined therebetween and which open bores of the plurality of hollow fiber membranes of the second membrane element fluidly communicate therewith; and
a tubesheet made of a polymeric material that is formed around the second end of the second membrane element, wherein open bores of the plurality of hollow fiber membranes at ends thereof that are adjacent the second end of the second membrane element are plugged by the polymeric material of the tubesheet;

a branched feed gas pipe fluidly communicating, in gas-tight fashion, between the feed gas inlet and each of the first ends of the hollow porous center tubes;
a left-side permeate outlet pipe fluidly communicating, in gas-tight fashion, with the first membrane element permeate tube and extending through the left-side permeate outlet in gas-tight fashion;
a right-side permeate outlet pipe fluidly communicating, in gas-tight fashion, with the second membrane element permeate tube and extending through the right-side permeate outlet in gas-tight fashion;
a retentate outlet pipe fluidly communicating between the retentate outlet and a retentate collection space disposed between an inner surface of the tubular pressure vessels and outer surfaces of the first and second membrane elements;
a first heat exchanger tube having a pressure reduction valve or orifice disposed at a first end thereof and which penetrates the annular cap of the first membrane element so as to fluidly communicate with the permeate collection space thereof; and
a second heat exchanger tube having a pressure reduction valve or orifice disposed at a first end thereof and which penetrates the annular cap of the second membrane element so as to fluidly communicate with the permeate collection space thereof.

2. The membrane module of claim 1 , wherein each of the plurality of hollow fiber membranes of the first and second membrane elements are selective for water and C 3+ hydrocarbons over methane.

3. A method of gas separation utilizing an internally reheated sweep gas, comprising the steps of:
providing the double-ended, counter-flow gas separation membrane module with internally reheated sweep gas of claim 1 ;
feeding a stream of a gas mixture to the branched feed gas pipe, the gas mixture comprising first and second gases;
withdrawing a permeate gas from the right and left-side permeate outlet pipes that is enriched in the first gas in comparison to the gas mixture; and
withdrawing a retentate gas from the retentate outlet that is enriched in the second gas in comparison to the gas mixture.

4. The method of claim 3 , wherein the gas mixture is natural gas, the first gas is C 3+ hydrocarbons and the second gas is CH 4 .

5. The method of claim 4 , wherein said method is performed aboard a floating production storage and offloading vessel.

6. A method of dew pointing natural gas aboard a floating production storage and offloading vessel using a gas separation module utilizing an internally reheated sweep gas, comprising the steps of:
providing a gas separation membrane module comprising a pressure vessel enclosing two membrane elements each of which comprises a plurality of hollow fiber gas separation membranes extending between a polymeric nub on one end of the respective membrane element and a polymeric tubesheet on the other end of the respective membrane element and also enclosing two heat exchangers each of which has a pressure reduction valve or orifice at a first end in fluid communication with a retentate gas space of the module and a second end in fluid communication with a permeate gas space of the module;
feeding a stream of a gas mixture, comprising C 3+ hydrocarbons and methane, to a feed gas inlet of the module that is centrally disposed with respect to a longitudinal axis of the module, the gas mixture having a first dew point;
separating, with the module, the stream of the gas mixture into a C3+ hydrocarbons enriched and methane deficient permeate gas and a methane enriched and C3+ hydrocarbons deficient retentate gas;
withdrawing the permeate gas from first and second permeate outlet pipes disposed at opposite ends of the module; and
withdrawing a main portion of retentate gas from a retentate outlet of the module, the main portion having a second dew point lower than the first dew point, wherein the permeate gas space of the gas module is swept by a remaining portion of the retentate gas without resulting in condensation of C3+ hydrocarbons in the permeate gas space through expansion of the remaining portion by the pressure reduction valve or orifice, warming of the expanded remaining portion through heat exchange with the main portion of the retentate gas in the retentate gas space, and introduction of the warmed expanded remaining portion into the permeate gas space.

Assignees

• Air Liquide Advanced Tech Us Llc

Inventors

• Karode Sandeep K
• Bikson Benjamin
• Bailey Michael E
• Arruda Manuel

Classifications

• B01D2311/13

  Use of sweep gas · CPC title

• B01D2257/7025

  Methane · CPC title

• B01D2257/80

  Water · CPC title

• B01D2313/21

  Specific headers, end caps · CPC title

• B01D2256/24

  Hydrocarbons · CPC title