Advanced C2-splitter feed rectifier

• US 9,103,586 B2
• Filed: 12/16/2006
• Issued: 08/11/2015
• 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
• Primary Examiner(s): Ciric, Ljiljana
• Assistant Examiner(s): COX, ALEXIS K
• Application Number:
  US11/639,909
• Publication Number:
  US 20080141713A1
• Time in Patent Office: 3,160 Days
• Field of Search: 62617-620, 626/30, 626/31
• US Class Current: 1/1
• CPC Class Codes: C07C 11/02 Alkenes
• CPC Class Codes: C07C 11/24 Acetylene production of acetylene gas by wet methods C10H
• CPC Class Codes: C07C 7/005 Processes comprising at least two steps in series
• CPC Class Codes: F25J 2200/74 Refluxing the column with at least a part of the partially condensed overhead gas
• CPC Class Codes: F25J 2200/78 Refluxing the column with a liquid stream originating from an upstream or downstream fractionator column
• CPC Class Codes: F25J 2215/62 Ethane or ethylene
• CPC Class Codes: F25J 2270/90 External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
• CPC Class Codes: F25J 2290/80 Retrofitting, revamping or debottlenecking of existing plant
• 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

Abstract

Processes to separate a light hydrocarbon stream comprising ethylene, ethane, and C3+ hydrocarbons into an ethylene stream, an ethane stream, and a C3+ hydrocarbon stream, including: feeding the light hydrocarbon stream to a deethanizer; separating the light hydrocarbons in the deethanizer to form a C3+ hydrocarbon bottoms stream and a C2-rich overhead stream comprising ethylene and ethane; separating the C2-rich stream in a C2-rectifier to form a first ethylene stream and an ethane-rich bottoms stream; and separating the ethane-rich bottoms stream in a C2-splitter to form a second ethylene stream and an ethane stream.

Claims

1. A process to separate one or more light hydrocarbon streams comprising ethylene, ethane, and C3+ hydrocarbons into an ethylene stream, an ethane stream, and a C3+ hydrocarbon stream, comprising:

feeding the one or more light hydrocarbon streams to a deethanizer;

separating the light hydrocarbons in the deethanizer to form a C3+ hydrocarbon bottoms stream and a C2-rich overhead stream comprising ethylene and ethane;

separating the C2-rich overhead stream in a C2-rectifier to form a first ethylene stream and an ethane-rich bottoms stream, wherein the C2-rectifier is operated without reboiling the ethylene introduced to the C2-rectifier;

separating the ethane-rich bottoms stream in a C2-splitter to form a second ethylene stream and an ethane stream; and

mixing the first ethylene stream and the second ethylene stream to form a combined ethylene stream.

2. The process of claim 1, wherein the C2-rich overhead stream further comprises acetylene, and the process further comprises

recovering the acetylene in an acetylene recovery unit to form an acetylene stream and a stream lean in acetylene;

and

separating the stream lean in acetylene in the C2-rectifier to form the ethylene stream and the ethane-rich bottoms stream.

3. The process of claim 1 wherein the C2-rich overhead stream further comprises acetylene, the process further comprising:

contacting the C2-rich overhead stream with a hydrogen rich stream in an acetylene converter unit to convert the acetylene to ethane and ethylene to form a stream lean in acetylene; and

feeding the acetylene-lean stream to the C2-rectifier.

4. The process of claim 1 wherein the one or more light hydrocarbon streams comprise a product stream from a depropanizer, a demethanizer, a debutanizer, a demethanizer stripper, a cracker furnace effluent, or a combination thereof.

5. The process of claim 1 wherein the C2-splitter is fitted with a reboiler to further increase an amount of the second ethylene stream separated from the ethane-rich bottoms stream.

6. The process of claim 1, further comprising refluxing a portion of the ethylene as ethylene condensate to the C2-rectifier.

7. The process of claim 1, further comprising condensing the combined ethylene stream to provide an ethylene condensate and refluxing at least a portion of the ethylene condensate to the C2-splitter.

8. The process of claim 1, wherein the C2 rich overhead stream is introduced to the C2 rectifier as a vapor.

9. The process of claim 1, wherein the C2-rich overhead stream is introduced to the C2 rectifier at a location below a bottom tray of the C2 rectifier and wherein the C2 splitter comprises two reboilers and one side condenser.

10. A method to retrofit a process to separate light hydrocarbons comprising operation of a deethanizer to separate the light hydrocarbons into a C3+ hydrocarbon bottoms stream and a C2-rich overheads stream comprising ethylene and ethane, and a C2-splitter to separate the C2-rich overheads into an ethylene stream and an ethane stream, wherein the ethylene is condensed and collected in a C2-splitter overheads condensation system, and wherein the C2-splitter is capacity-limited, the method comprising:

installing a C2-rectifier to separate the C2-rich overheads stream from the deethanizer into a first ethylene stream and an ethane-rich stream, wherein the C2-rectifier is operated without reboiling the ethylene introduced to the C2-rectifier;

installing a line to transmit the C2-rich overheads stream to the C2-rectifier;

installing a line to transmit the ethane-rich stream from the C2-rectifier to the C2-splitter; and

installing a line to transmit the first ethylene stream to the C2-splitter overheads condensation system such that the first ethylene stream mixes with the ethylene stream from the C2-splitter.

11. The method of claim 10 further comprising:

installing a line to transmit a reflux from the C2-splitter overheads condensation system to the C2-rectifier.

12. The method of claim 11 further comprising installing a C2-rectifier overheads condensation system to condense and collect the ethylene in the first ethylene stream and to supply reflux to the C2-rectifier.

13. The method of claim 10 further comprising:

installing a line to transmit reflux from the C2-splitter overheads condensation system to the C2-rectifier; and

installing a line to collect the first ethylene stream as a side-draw from the C2-rectifier.

14. The method of claim 10 wherein the process to separate light hydrocarbons further comprises operating an acetylene recovery unit.

15. The method of claim 10 wherein the C2-splitter is fitted with a reboiler to further increase an amount of the ethylene stream separated from the ethane-rich stream.

16. A method for olefin production, comprising:

separating one or more light hydrocarbon streams comprising ethylene, ethane, and one or more C3+ hydrocarbons into a C2 hydrocarbon-containing stream and a C3+ hydrocarbon-containing stream;

rectifying the C2 hydrocarbon-containing stream in a C2-rectifier into a first ethylene stream and an ethane-rich bottoms stream by contacting the C2 hydrocarbon-containing stream with a liquid, ethylene rich stream, wherein the C2-rectifier is operated without reboiling the ethylene introduced to the C2-rectifier;

separating the ethane-rich bottoms stream to form a second ethylene stream and an ethane stream;

mixing the first ethylene stream and the second ethylene stream to form a combined ethylene stream; and

condensing the combined ethylene stream to provide an ethylene condensate.

17. The method of claim 16, wherein rectifying the C2 hydrocarbon-containing stream into a first ethylene stream and an ethane-rich bottoms stream is performed in a rectifier wherein vapor from the C2 hydrocarbon-containing stream is contacted with the liquid of the liquid, ethylene rich stream.

18. The method of claim 16, wherein rectifying the C2 hydrocarbon-containing stream into a first ethylene stream and an ethane-rich bottoms stream is performed in a rectifier having a fractional distillation zone wherein vapor from the C2 hydrocarbon-containing stream is contacted with the liquid of the liquid, ethylene rich stream.