Claims
- 1. A process for preventing the accumulation of undesirable oxides of nitrogen during the recovery of one or more desired hydrocarbons from cat-cracked gas comprising:
- passing said gas through an alkaline solution to remove acid gases;
- passing said gas through a depropanizer at a temperature between about -28.89.degree. C. (-20.degree. F.) to -40.degree. C. (-40.degree. F.) to form a first portion and a second portion;
- passing said first portion through an absorber demethanizer at a temperature above about -45.56.degree. (-50.degree. F.) to form a third portion and a fourth portion;
- recovering at least one desired hydrocarbon from said third portion at temperatures above about -106.67.degree. C. (-160.degree. F.).
- 2. The process of claim 1 wherein said recovering step comprises chilling said third portion to a temperature between about -78.89.degree. C. (-110.degree. F.) and -101.11.degree. C. (-150.degree. F.) whereby said third portion is separated into a fifth and a sixth portion.
- 3. The process of claim 2 wherein said chilling step comprises heat exchanging said sixth portion with said third portion after expansion of said third portion.
- 4. The process of claim 3 wherein said expansion is a Joule Thomson expansion.
- 5. The process of claim 1 wherein said first portion primarily comprises hydrocarbons having no more than three carbon atoms and said second portion primarily comprises hydrocarbons having at least four carbon atoms.
- 6. The process of claim 4 wherein said first portion primarily comprises hydrocarbons having no more than three carbon atoms and said second portion primarily comprises hydrocarbons having at least four carbon atoms.
- 7. The process of claim 1 wherein said third portion primarily comprises compounds selected from the group consisting of methane, hydrogen, nitrogen-containing compounds, and a small proportion of hydrocarbons having two and three carbon atoms, and said fourth portion primarily comprises hydrocarbons having at least two carbon atoms.
- 8. The process of claim 6 wherein said third portion primarily comprises compounds selected from the group consisting of methane, hydrogen, nitrogen-containing compounds, and a small proportion of hydrocarbons having two and three carbon atoms, and said fourth portion primarily comprises hydrocarbons having at least two carbon atoms.
- 9. The process of claim 2 wherein said fifth portion comprises a fraction enriched in hydrocarbons having two and three carbon atoms and said sixth portion primarily comprises compounds selected from the group consisting of hydrogen, methane, and nitric oxide.
- 10. The process of claim 8 wherein said fifth portion primarily comprises hydrocarbons having two and three carbon atoms and said sixth portion primarily comprises compounds selected from the group consisting of hydrogen, methane, and nitric oxide.
- 11. The process of claim 1 wherein said recovering step comprises absorbing said at least one desired hydrocarbon from said third portion using a hydrocarbon absorbent having more than three carbon atoms.
- 12. The process of claim 1 wherein said first portion is passed through said absorber demethanizer at temperatures between about -28.89.degree. C. (-20.degree. F.) and -40.degree. C. (-40.degree. F.).
- 13. The process of claim 12 wherein said recovering step comprises chilling said third portion to a temperature between about -78.89.degree. C. (-110.degree. F.) and -101.11.degree. C. (-150.degree. F.) whereby said third portion is separated into a fifth and a sixth portion.
- 14. The process of claim 13 wherein said chilling step comprises heat exchanging said sixth portion with said third portion after expansion of said third portion.
- 15. The process of claim 14 wherein said expansion is Joule Thomson expansion.
- 16. The process of claim 12 wherein said first portion primarily comprises hydrocarbons having no more than three carbon atoms and said second portion primarily comprises hydrocarbons having at least four carbon atoms.
- 17. The process of claim 13 wherein said first portion primarily comprises hydrocarbons having no more than three carbon atoms and said second portion primarily comprises hydrocarbons having at least four carbon atoms.
- 18. The process of claim 16 wherein said third portion primarily comprises compounds selected from the group consisting of methane, hydrogen, nitrogen-containing compounds, and a small proportion of hydrocarbons having two and three carbon atoms, and said fourth portion primarily comprises hydrocarbons having at least two carbon atoms.
- 19. The process of claim 17 wherein said third portion primarily comprises compounds selected from the group consisting of methane, hydrogen, nitrogen-containing compounds, and a small proportion of hydrocarbons having two and three carbon atoms, and said fourth portion primarily comprises hydrocarbons having at least two carbon atoms.
- 20. The process of claim 18 wherein said fifth portion primarily comprises a fraction enriched in hydrocarbons having two and three carbon atoms and said sixth portion primarily comprises compounds selected from the group consisting of hydrogen, methane, and nitric oxide.
- 21. The process of claim 19 wherein said fifth portion primarily comprises hydrocarbons having two and three carbon atoms and said sixth portion primarily comprises compounds selected from the group consisting of hydrogen, methane, and nitric oxide.
- 22. The process of claim 12 wherein said recovering step comprises absorbing said at least one desired hydrocarbon from said third portion using a hydrocarbon absorbent having more than three carbon atoms.
- 23. The process of claim 13 wherein said temperature of said third portion is reduced to between about -78.89.degree. C. (-110.degree. F.) and -90.degree. C. (-130-.degree. F.) during said chilling step.
- 24. The process of claim 19 wherein said temperature of said third portion is reduced to between about -78.89.degree. C. (-110.degree. F.) and -90.degree. C. (-13020 F.) during said chilling step.
- 25. The process of claim 12 wherein said desired hydrocarbon is an olefin.
- 26. The process of claim 24 wherein said desired hydrocarbon is an olefin.
Parent Case Info
This is a continuation of application Ser. No. 07/967,835, filed Oct. 28, 1992, now U.S. Pat. No. 5,444,176.
US Referenced Citations (3)
Continuations (1)
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Number |
Date |
Country |
Parent |
967835 |
Oct 1992 |
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