PURIFICATION OF CARBON DIOXIDE

• US 20150114032A1
• Filed: 10/22/2014
• Published: 04/30/2015
• Est. Priority Date: 04/26/2012
• Status: Active Grant

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Higginbotham, Paul, Palamara, John Eugene, Guvelioglu, Galip Hakan
• Granted Patent: US 10,655,912 B2
• Time in Patent Office: Days
• US Class Current: 62/606
• CPC Class Codes: B01D 2256/22 Carbon dioxide
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 53/002 by condensation
• CPC Class Codes: C01B 17/167 Separation
• CPC Class Codes: F25J 1/0027 Oxides of carbon, e.g. CO2
• CPC Class Codes: F25J 2200/02 in a single pressure main column system
• CPC Class Codes: F25J 2200/04 in a dual pressure main column system
• CPC Class Codes: F25J 2200/30 using a side column in a single pressure column system
• CPC Class Codes: F25J 2200/40 Features relating to the provision of boil-up in the bottom of a column
• CPC Class Codes: F25J 2200/50 using multiple (re-)boiler-condensers at different heights of the column
• CPC Class Codes: F25J 2200/74 Refluxing the column with at least a part of the partially condensed overhead gas
• CPC Class Codes: F25J 2200/76 Refluxing the column with condensed overhead gas being cycled in a quasi-closed loop refrigeration cycle
• CPC Class Codes: F25J 2200/78 Refluxing the column with a liquid stream originating from an upstream or downstream fractionator column
• CPC Class Codes: F25J 2210/06 Splitting of the feed stream, e.g. for treating or cooling in different ways
• CPC Class Codes: F25J 2215/80 Carbon dioxide
• CPC Class Codes: F25J 2220/84 Separating high boiling, i.e. less volatile components, e.g. NOx, SOx, H2S
• CPC Class Codes: F25J 2230/80 the fluid being carbon dioxide
• CPC Class Codes: F25J 2235/02 using a pump in general or hydrostatic pressure increase
• CPC Class Codes: F25J 2235/80 the fluid being carbon dioxide
• CPC Class Codes: F25J 2240/02 Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 2240/30 : Dynamic liquid or hydraulic expansion with extraction of work, e.g. single phase or two-phase turbine
• CPC Class Codes: F25J 2245/02 : Recycle of a stream in general, e.g. a by-pass stream
• CPC Class Codes: F25J 2260/20 : Integration in an installation for liquefying or solidifying a fluid stream
• CPC Class Codes: F25J 2260/80 : Integration in an installation using carbon dioxide, e.g. for EOR, sequestration, refrigeration etc.
• CPC Class Codes: F25J 2270/02 : Internal refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 2270/80 : Quasi-closed internal or closed external carbon dioxide refrigeration cycle
• CPC Class Codes: F25J 2270/88 : Quasi-closed internal refrigeration or heat pump cycle, if not otherwise provided
• CPC Class Codes: F25J 2290/40 : Vertical layout or arrangement of cold equipments within in the cold box, e.g. columns, condensers, heat exchangers etc.
• CPC Class Codes: F25J 3/0266 : separation of carbon dioxide production of carbon dioxide in general C01B32/00
• CPC Class Codes: F25J 3/08 : Separating gaseous impurities from gases or gaseous mixtures or from liquefied gases or liquefied gaseous mixturescold traps B01D8/00
• CPC Class Codes: Y02P 20/129 : Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
• CPC Class Codes: Y02P 20/151 : Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

Impurities that are less volatile than carbon dioxide, e.g. hydrogen sulfide, are removed from crude carbon dioxide by processes involving distillation of said crude carbon dioxide in a distillation column system operating at super-atmospheric pressure(s) to produce carbon dioxide-enriched overhead vapor and bottoms liquid enriched with said impurities. Where such processes involve a single heat pump cycle, significant savings in power consumption are realized when the distillation column system is re-boiled by at least partially vaporizing liquid in or taken from an intermediate location in the column system.

Claims

1. A process for purifying crude carbon dioxide comprising at least one impurity that is less volatile than carbon dioxide, said process comprising:

feeding crude carbon dioxide to a distillation column system operating at super-atmospheric pressure(s) for separation to produce carbon dioxide-enriched overhead vapor and bottoms liquid enriched with said at least one impurity;

providing carbon dioxide-enriched liquid as reflux for said distillation column system;

re-boiling said distillation column system by at least partially vaporizing impurity-enriched bottoms liquid and at least one intermediate liquid in or taken from an intermediate location in said distillation column system by indirect heat exchange to provide vapor for said distillation column system;

removing carbon dioxide-enriched overhead vapor from said distillation column system; and

removing impurity-enriched bottoms liquid, or a liquid derived from impurity-enriched bottoms liquid, from said distillation column system,

wherein said process comprises a heat pump cycle using as a working fluid a carbon dioxide-containing fluid from said distillation column system; and

wherein said intermediate liquid, or at least one of said intermediate liquids, is at least partially vaporized by said indirect heat exchange against carbon dioxide-enriched overhead vapor from said distillation column system, thereby at least partially condensing said carbon dioxide-enriched overhead vapor.

2. The process of claim 1, wherein the intermediate liquid, or at least one of the intermediate liquids, is enriched in the at least one less volatile impurity.

3. The process of claim 1, wherein said heat pump cycle comprises:

after optionally at least partially vaporizing said carbon dioxide-containing working fluid from said distillation column system by indirect heat exchange, warming said carbon dioxide-containing working fluid by indirect heat exchange to produce warmed carbon dioxide-containing gas;

compressing said warmed carbon dioxide-containing gas to form compressed carbon dioxide-containing recycle gas;

cooling and optionally at least partially condensing said compressed carbon dioxide-containing recycle gas by indirect heat exchange to produce cooled carbon dioxide-containing recycle fluid; and

recycling at least a portion of said cooled carbon dioxide-containing recycle fluid to said distillation column system,

wherein said working fluid is expanded as required either prior to said optional vaporization and warming to produce said warmed carbon dioxide-containing gas, or after said cooling and optional at least partial condensation to produce said cooled carbon-dioxide containing recycle fluid prior to recycling said cooled carbon dioxide-containing recycle fluid to said distillation column system.

7. The process of claim 3, wherein said carbon dioxide-containing working fluid is said carbon dioxide-enriched overhead vapor from said distillation column system.

9. The process of claim 1, wherein said working fluid is carbon dioxide-enriched overhead vapor, said heat pump cycle comprising:

warming said carbon dioxide-enriched overhead vapor by indirect heat exchange to produce warmed carbon dioxide-enriched gas;

compressing said carbon dioxide-enriched gas to produce compressed carbon dioxide-enriched recycle gas;

using said compressed carbon dioxide-enriched recycle gas to provide at least a part of the reboil duty required to vaporize said intermediate liquid(s) thereby cooling and condensing said compressed carbon dioxide-enriched recycle gas to produce carbon dioxide-enriched liquid;

expanding said carbon dioxide-enriched liquid to produce expanded carbon dioxide-enriched liquid; and

using at least a portion of said expanded carbon dioxide-enriched liquid to provide said reflux to said distillation column system.

10. The process of claim 3, wherein said carbon dioxide-containing working fluid is said intermediate liquid from said distillation column system.

14. The process of claim 1, wherein said working fluid is an intermediate liquid from said distillation column system, said heat pump cycle comprising:

expanding said intermediate liquid to produce expanded intermediate liquid;

vaporizing said expanded intermediate liquid by indirect heat exchange against said carbon dioxide-enriched overhead vapor to produce intermediate gas and condensed carbon dioxide-enriched overhead vapor;

compressing said intermediate gas to produce compressed intermediate recycle gas;

cooling said compressed intermediate recycle gas by indirect heat exchange to produce cooled intermediate recycle gas; and

feeding said cooled intermediate recycle gas to said distillation column system,

wherein said condensed carbon dioxide-enriched overhead vapor is used at least in part as said carbon dioxide-enriched liquid providing said reflux to said distillation column system.

16. The process of claim 1, wherein a portion of said working fluid is purged from said process.

17. The process of claim 1, wherein said reflux for said distillation column system is provided by at least one condensed recycle fluid from said heat pump cycle after suitable pressure reduction.

18. The process of claim 1, wherein the refrigeration duty required to cool and at least partially condense at least one recycle fluid from said heat pump cycle is provided by indirect heat exchange against at least one “

cold”

process stream.

19. The process of claim 1, wherein said crude carbon dioxide is crude carbon dioxide fluid derived from a natural source of carbon dioxide and expanded prior to feeding to said distillation column system.

25. The process of claim 1, wherein said crude carbon dioxide is derived from supercritical crude carbon dioxide fluid and carbon dioxide-enriched liquid is produced as a product.

29. The process of claim 1, wherein said crude carbon dioxide is derived from crude carbon dioxide vapor and carbon dioxide-enriched gas is produced as a product.

33. The process of claim 1, wherein said impurity-enriched bottoms liquid, or said liquid derived from impurity-enriched bottoms liquid, is pumped and warmed by indirect heat exchange to provide impurity-rich waste liquid.

36. The process of claim 1, wherein the operating pressure(s) said distillation column system is from about 10 bar to about 25 bar.

37. The process of claim 1, wherein said at least one impurity is hydrogen sulfide (H₂S).

38. The process of claim 1, wherein said process is auto-refrigerated.

39. The process of claim 1, wherein said heat pump cycle has a single recycle pressure.

40. Apparatus for carrying out the process of claim 9, said apparatus comprising:

a distillation column system for operation at super-atmospheric pressure(s) for separating crude carbon dioxide feed to produce carbon-dioxide-enriched overhead vapor and bottoms liquid enriched with said at least one impurity;

a first heat exchanger arrangement in fluid flow communication with said distillation column system for warming at least a portion of said carbon dioxide-enriched overhead vapor by indirect heat exchange to produce warmed carbon dioxide-enriched gas;

a compressor system in fluid flow communication with said first heat exchanger arrangement for compressing said warmed carbon dioxide-enriched gas to produce at least one compressed carbon dioxide-enriched recycle gas;

a second heat exchanger arrangement in fluid flow communication with said compressor system for cooling and at least partially condensing at least a portion of said compressed carbon dioxide-enriched recycle gas by indirect heat exchange to produce carbon dioxide-enriched liquid and vapor for the distillation column system;

a first expansion device in fluid flow communication with said second heat exchanger arrangement for expanding said carbon dioxide-enriched liquid to produce expanded carbon dioxide-enriched liquid;

a conduit arrangement for feeding expanded carbon dioxide-enriched liquid as reflux to said distillation column system; and

a third heat exchanger arrangement for re-boiling said impurity-enriched bottoms liquid by indirect heat exchange to produce vapor for said distillation column system.

41. Apparatus for carrying out the process of claim 14, said apparatus comprising:

a distillation column system for operation at super-atmospheric pressure(s) for separating crude carbon dioxide feed to produce carbon-dioxide-enriched overhead vapor and bottoms liquid enriched with said at least one impurity;

a first expansion device in fluid flow communication with said distillation column system for expanding an intermediate liquid from said distillation column system to produce expanded intermediate liquid;

a first heat exchanger arrangement in fluid flow communication with said first expansion device for vaporizing at least a portion of said expanded intermediate liquid by indirect heat exchange against carbon dioxide-enriched overhead vapor in or taken from said distillation column system to produce expanded intermediate gas and condensed carbon dioxide-enriched overhead vapor;

a compressor system in fluid flow communication with said first distillation column system for compressing said expanded intermediate gas to produce compressed intermediate recycle gas;

a second heat exchanger arrangement in fluid flow communication with said compressor system for cooling said compressed intermediate recycle gas by indirect heat exchange to produce cooled intermediate recycle gas; and

a conduit arrangement for feeding said cooled intermediate recycle gas as supplementary feed to said distillation column system.

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