Dual column nitrogen producing air separation unit with split kettle reboil and integrated condenser-reboiler

Patent metadata

Field	Value
Publication number	US-11933540-B2
Application number	US-202318300033-A
Country	US
Kind code	B2
Filing date	Apr 13, 2023
Priority date	Jun 4, 2020
Publication date	Mar 19, 2024
Grant date	Mar 19, 2024

Abstract

Enhancements to a dual column, nitrogen producing cryogenic air separation unit are provided. Such enhancements include an improved air separation cycle that uses multiple condenser-reboilers and recycles a portion of the vapor from one or more of the condenser-reboilers to the incoming feed stream and or the compressed purified air streams to yield improvements in such dual column, nitrogen producing cryogenic air separation units. The multiple condenser-reboilers preferably include an integrated condenser-reboiler arrangement comprising a heat exchanger having a set of nitrogen condensing passages, a first set and second set of boiling passages, and a phase separator.

First claim

What is claimed is:

1. An integrated condenser-reboiler arrangement for a distillation column system comprising:
a phase separator; and
a once-through condenser-reboiler disposed within the phase separator, the once-through condenser-reboiler having a top section, an intermediate location, and a bottom section;
a plurality of condensing passages configured to receive a gaseous stream from the distillation column system at the top section of the once-through condenser-reboiler and condense the gaseous stream traversing through the plurality of condensing passages via indirect heat exchange with a first kettle stream and a second kettle stream to yield a condensate that exits the bottom section of the once-through condenser-reboiler;
a first set of boiling passages configured to receive the first kettle stream from the distillation column system at the bottom section of the once-through condenser-reboiler and partially vaporize the first condensing stream via indirect heat exchange with the gaseous stream traversing through the cooling passages to yield a dual phase boil off stream, and wherein the dual phase boil off stream is released from the top section of the once-through condenser-reboiler into the phase separator;
a second set of boiling passages configured to receive the second condensing medium from the phase separator at an intermediate location on the once-through condenser-reboiler and vaporize or partially vaporize the second condensing medium to yield another boil off stream that exits the top section of the once-through condenser-reboiler and directed back to the distillation column system;
wherein the phase separator is configured to separate the dual phase boil off stream into the second condensing medium and a recycle vapor stream.

2. The integrated condenser-reboiler arrangement of claim 1 wherein the recycle vapor stream is directed back to the distillation column system.

3. The integrated condenser-reboiler arrangement of claim 1 wherein the recycle vapor stream is directed back to a main heat exchanger associated with the distillation column system.

4. The integrated condenser-reboiler arrangement of claim 1 wherein the gaseous stream is a nitrogen enriched stream received from the distillation column system.

5. The integrated condenser-reboiler arrangement of claim 1 , wherein the integrated condenser-reboiler arrangement is disposed within a distillation column within the distillation column system.

6. The integrated condenser-reboiler arrangement of claim 1 , wherein the first kettle stream is a first portion of an oxygen enriched kettle stream received from the distillation column system and the second kettle stream from the distillation column system is directed to the phase separator vessel.

7. An integrated condenser-reboiler arrangement for a distillation column system comprising:
a phase separator;
a once-through condenser-reboiler in fluid communication with the phase separator, the once-through condenser-reboiler comprising:
a top section, an intermediate location, and a bottom section
a plurality of condensing passages configured to receive a gaseous stream from the distillation column system at the top section of the once-through condenser-reboiler and condense the gaseous stream traversing through the plurality of condensing passages via indirect heat exchange with a first kettle stream and a second kettle stream to yield a condensate that exits the bottom section of the once-through condenser-reboiler;
a first set of boiling passages configured to receive the first kettle stream from the distillation column system at the bottom section of the once-through condenser-reboiler and partially vaporize the first condensing stream via indirect heat exchange with the gaseous stream traversing through the cooling passages to yield a dual phase boil off stream, and wherein the dual phase boil off stream is released from the top section of the once-through condenser-reboiler into the phase separator;
a second set of boiling passages configured to receive the second condensing medium from the phase separator at an intermediate location on the once-through condenser-reboiler and vaporize or partially vaporize the second condensing medium to yield another boil off stream that exits the top section of the once-through condenser-reboiler and directed back to the distillation column system;
wherein the phase separator is configured to separate the dual phase boil off stream into the second condensing medium and a recycle vapor stream.

8. The integrated condenser-reboiler arrangement of claim 7 wherein the recycle vapor stream is directed back to the distillation column system.

9. The integrated condenser-reboiler arrangement of claim 7 wherein the recycle vapor stream is directed back to a main heat exchanger associated with the distillation column system.

10. The integrated condenser-reboiler arrangement of claim 7 wherein the gaseous stream is a nitrogen enriched stream received from the distillation column system.

11. The integrated condenser-reboiler arrangement of claim 7 , wherein the first kettle stream is a first portion of an oxygen enriched kettle stream received from the distillation column system and the second kettle stream from the distillation column system is directed to the phase separator vessel.

Assignees

• Tuo Hanfei
• Xu Zhengrong
• Praxair Technology Inc

Inventors

• Tuo Hanfei
• Xu Zhengrong

Classifications

• F25J3/04412 Primary

  in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column · CPC title

• F25J3/0257

  separation of nitrogen (from air F25J3/04, production of nitrogen in general C01B21/00) · CPC title

• F25J3/04012

  by compression of warm gaseous streams; details of intake or interstage cooling (F25J3/04048 takes precedence; operation of compressors F25J3/04781; particular layout of compressors used in air fractionation units F25J3/04866) · CPC title

• F25J3/04763

  Start-up or control of the process; Details of the apparatus used · CPC title

• F25J1/0012

  Primary atmospheric gases, e.g. air · CPC title