Integrated olefin recovery process

• US 20080141712A1
• Filed: 12/16/2006
• Published: 06/19/2008
• Est. Priority Date: 12/16/2006
• Status: Active Grant

• Current Assignee: Kellogg Brown & Root LLC (KBR Incorporated)
• Original Assignee: Kellogg Brown & Root LLC (KBR Incorporated)
• Inventors: Verma, Vijender Kumar
• Granted Patent: US 8,256,243 B2
• Time in Patent Office: Days
• US Class Current: 62/620
• CPC Class Codes: C07C 11/02 Alkenes
• CPC Class Codes: C07C 7/005 Processes comprising at least two steps in series
• 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 2200/74 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 2200/94 Details relating to the withdrawal point
• CPC Class Codes: F25J 2215/62 Ethane or ethylene
• CPC Class Codes: F25J 2230/08 Cold compressor, i.e. suction of the gas at cryogenic temperature and generally without afterstage-cooler
• CPC Class Codes: F25J 2270/02 Internal refrigeration with liquid vaporising loop
• 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 3/0219 Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature
• CPC Class Codes: F25J 3/0233 separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0238 separation of CnHm with 2 carbon atoms or more
• CPC Class Codes: F25J 3/0242 separation of CnHm with 3 carbon atoms or more
• CPC Class Codes: Y02P 20/10 Process efficiency

Abstract

Methods and apparatus for the integration of a fractionation process and an olefin refrigeration system, wherein the fractionation process olefin effluent is supplied to the refrigeration system, can eliminate a fractionation process condenser and reflux drum typically present. A plurality of bottoms streams can be collected from the fractionation process. The olefin refrigerant can be supplied to alternate olefin refrigerant consumers, as desired. A column in the fractionation process can be refluxed with an olefin stream from refrigeration system, and olefin product can be collected or exported via line.

Claims

1. ) A process for separating a light hydrocarbon stream comprising at least one alkane component and at least one olefin component, comprising:

supplying the light hydrocarbon streams to a fractionation column to obtain an overhead olefin vapor stream;

supplying a plurality of olefin refrigerant vapor streams to an olefin refrigeration compressor train, wherein one of the said plurality of streams comprises the overhead olefin vapor stream from the fractionation column;

chilling and condensing olefin refrigerant from the olefin refrigeration compressor train to obtain liquid olefin refrigerant;

refluxing the fractionation column with a first portion of the liquid olefin refrigerant;

using a second portion of the liquid olefin refrigerant to form at least one olefin refrigerant vapor stream for the supply to the olefin refrigerant compressor train; and

recovering a third portion of the liquid olefin refrigerant as an olefin product stream.

2. ) The process of claim 1 wherein the light hydrocarbon streams comprises propane and propylene and the fractionation column is a propane-propylene splitter.

3. ) The process of claim 1 wherein the light hydrocarbon streams comprises ethane and ethylene, and the fractionation column comprises an advanced deethanizer with the first portions of liquid olefin refrigerant refluxing a deethanizer column and an ethylene-ethane splitter.

4. ) The process of claim 3 further comprising heat pumping the ethylene-ethane splitter with ethylene from the ethylene refrigeration compressor train.

5. ) The process of claim 1 further comprising supplying a portion of the olefin refrigerant to additional refrigerant consumers for heating and expansion, and returning olefin refrigerant vapor from the additional refrigerant consumers to the olefin refrigeration compressor train.

6. ) A process for deethanizing a light hydrocarbon stream comprising olefins, comprising:

supplying at least one light hydrocarbon stream comprising ethylene and ethane to a deethanizer;

feeding a side stream of ethylene and ethane from the deethanizer to an ethylene-ethane splitter;

supplying ethylene vapor from the deethanizer and splitter to an ethylene refrigeration compressor train to form ethylene liquid;

refluxing the deethanizer and splitter with a portion of the ethylene liquid from the refrigeration train;

recovering and exporting a portion of the ethylene liquid from the refrigeration train; and

recovering ethane liquid from the splitter.

7. ) The process of claim 6, further comprising heat pumping the ethylene-ethane splitter with ethylene from the ethylene refrigeration compressor train.

8. ) The process of claim 6, further comprising supplying a portion of the ethylene liquid from the ethylene refrigeration compressor train to additional refrigeration consumers.

9. ) The process of claim 8, further comprising returning ethylene vapor from the additional refrigeration consumers to the ethylene refrigeration compressor train.

10. ) An apparatus for deethanizing light hydrocarbons comprising olefins, the apparatus comprising:

a line to feed a hydrocarbon stream comprising ethane and ethylene to a deethanizer;

a line to supply an ethylene-ethane side draw from the deethanizer to an ethylene-ethane splitter;

lines for supplying ethylene vapor from the deethanizer and the splitter to an ethylene refrigeration compressor train;

lines for refluxing the deethanizer and splitter with liquid ethylene from the refrigeration compressor train;

a first product line for collecting liquid ethane from the splitter; and

a second product line for collecting liquid ethylene from the ethylene refrigeration compressor train.

11. ) The apparatus of claim 10 further comprising a line for heat pumping the splitter with ethylene from the ethylene refrigeration compressor train.

12. ) The apparatus of claim 10 further comprising lines to supply ethylene liquid to a plurality of refrigeration consumers for heating refrigeration, and to return ethylene vapor from the refrigeration consumers to the ethylene refrigeration compressor train.

13. ) A method for retrofitting an advanced deethanizer for operating the deethanizer without an overhead condenser, reflux drum or reflux pump, comprising the steps of:

providing an advanced deethanizer to receive hydrocarbon feeds stream comprising ethane and ethylene to obtain an overhead ethylene vapor stream, an overhead condenser for cooling the ethylene vapor stream, an ethylene-ethane splitter supplied with a side draw from the deethanizer to obtain ethylene overhead vapor and ethane bottom streams, and an ethylene refrigeration compressor train, wherein the compressor train is supplied with the ethylene overhead vapor stream from the splitter;

installing a line to bypass the overhead condenser and supply the overhead ethylene vapor stream from the deethanizer to the ethylene refrigeration compressor train; and

installing a line from the refrigeration compressor train to supply liquid ethylene to reflux the deethanizer.

14. ) In a process for recovering olefins from a cracking furnace effluent, comprising compression of the effluent and fractionation in a demethanizer, deethanizer, depropanizer, debutanizer, ethylene-ethane splitter and propane-propylene splitter, to obtain purified streams of at least ethane, ethylene, propane and propylene, the improvement comprising:

supplying at least one light hydrocarbon stream comprising ethylene and ethane to the deethanizer;

feeding a side stream of ethylene and ethane from the deethanizer to the ethylene-ethane splitter;

supplying ethylene vapor from the deethanizer and splitter to an ethylene refrigeration compressor train to form ethylene liquid; and

refluxing the deethanizer and splitter with a portion of ethylene liquid from the refrigeration train.

15. ) In a process for recovering olefins from a cracking furnace effluent, comprising compression of the effluent and fractionation in a demethanizer, deethanizer, depropanizer, debutanizer, ethylene-ethane splitter and propane-propylene splitter, to obtain purified streams of at least ethane, ethylene, propane and propylene, the improvement comprising:

feeding at least one light hydrocarbon stream comprising ethylene and ethane to the deethanizer to obtain an ethylene-ethane overhead vapor stream;

supplying the overhead vapor stream from the deethanizer to the ethylene-ethane splitter to obtain an overhead ethylene vapor stream;

supplying the ethylene vapor stream from the splitter to an ethylene refrigeration compressor train to obtain ethylene liquid;

refluxing the ethylene-ethane splitter with the ethylene liquid;

refluxing the deethanizer with a liquid sidedraw from the splitter; and

recovering and exporting a portion of the ethylene refrigerant.

16. ) The improvement of claim 15, further comprising heat pumping the ethylene-ethane splitter with ethylene from the ethylene refrigeration compressor train.

17. ) The improvement of claim 15, further comprising supplying a portion of the ethylene liquid to additional refrigeration consumers for refrigeration, and returning ethylene vapor from the additional refrigeration consumers to the ethylene refrigeration compressor train.

18. ) The improvement of claim 15, wherein the process comprises a front end high pressure demethanizer scheme, wherein the overhead vapor stream is supplied from the deethanizer directly to a acetylene converter, through a drum and then to the ethylene-ethane splitter, and wherein the liquid sidedraw from the splitter is pumped to the accumulator and then from the accumulator to the deethanizer.

19. ) The improvement of claim 15, wherein the process comprises a front end standard pressure demethanizer scheme, wherein the overhead vapor stream is supplied from the deethanizer directly to a acetylene converter, through a green oil wash tower in contact with a portion of the splitter sidedraw and then to the ethylene-ethane splitter, and wherein the splitter sidedraw is pumped to the green oil wash tower and to the deethanizer.

20. ) The improvement of claim 20, wherein a sidestream of the splitter sidedraw is pumped to the green oil wash tower and then from the green oil wash tower to the deethanizer.

21. ) An apparatus for separating a light hydrocarbon stream comprising at least one alkane component and at least one olefin component, comprising:

means for supplying the light hydrocarbon stream to a fractionation column to obtain an overhead olefin vapor stream;

means for supplying a plurality of olefin refrigerant vapor streams to an olefin refrigeration compressor train, wherein one of the said plurality of streams comprises the overhead olefin vapor stream from the fractionation column;

means for chilling and condensing olefin refrigerant from the olefin refrigeration compressor train to obtain liquid olefin refrigerant;

means for refluxing the fractionation column with a first portion of the liquid olefin refrigerant;

means for expanding and heating a second portion of the liquid olefin refrigerant to form at least one olefin refrigerant vapor stream for the supply to the olefin refrigerant compressor train; and

means for recovering a third portion of the liquid olefin refrigerant as an olefin product stream.