Claims
- 1. In a process for the fractionation of a gas comprising a mixture of hydrocarbons and inerts in a distillation column having at least one feed point to produce a gaseous overhead fraction containing lighter hydrocarbons and a bottoms product fraction containing heavier hydrocarbons, the improvement comprising the step of passing a physical scrubbing agent into an upper section of the column to scrub out from said gaseous overhead fraction containing lighter hydrocarbons, a heavier hydrocarbon fraction thereof which would otherwise be withdrawn from the column in said gaseous overhead fraction, thereby producing a gaseous overhead fraction containing a lower concentration of heavier hydrocarbons than would be the case without said scrubbing step, and wherein said scrubbing agent introduced into said upper column section contains at least a portion of said heavy hydrocarbon bottoms fraction.
- 2. A process according to claim 1, wherein said scrubbing agent consists essentially of said heavy hydrocarbon bottoms fraction.
- 3. A process according to claim 2, wherein said gas comprising a mixture of hydrocarbons, prior to entering the distillation column, is cooled to form liquid and gaseous phases and both of said phases are fed to the distillation column.
- 4. A process according to claim 3, further comprising withdrawing a secondary gaseous fraction from the middle of the column, but below the lowermost feed point.
- 5. A process according to claim 4, further comprising subcooling the scrubbing agent prior to passing same into the column.
- 6. A process according to claim 3, further comprising subcooling the scrubbing agent prior to passing same into the column.
- 7. A process according to claim 3, wherein said scrubbing medium is cooled to a temperature of between -30.degree. and +30.degree. C.
- 8. A process according to claim 7, wherein the distillation column is operated at a pressure of between 10 and 42 bar.
- 9. A process according to claim 2, further comprising withdrawing a secondary gaseous fraction from the middle of the column, but below the lowermost feed point.
- 10. A process according to claim 9, further comprising liquefying the secondary gaseous fraction under pressure.
- 11. A process according to claim 9, further comprising subcooling the scrubbing agent prior to passing same into the column.
- 12. A process according to claim 9, further comprising withdrawing liquid from the distillation column at a point where the liquid is cooler than the bottoms liquid and cooling said scrubbing agent in indirect heat exchange relationship with said withdrawn liquid.
- 13. A process according to claim 9, wherein said gas comprising a mixture of hydrocarbons is rich in C.sub.2 + hydrocarbons, the C.sub.2 and C.sub.3 content of the physical scrubbing agent is less than 5 mol % and less than 10 mol %, respectively, and said secondary gaseous fraction is rich in C.sub.2 and C.sub.3 hydrocarbons having a content of methane and lighter hydrocarbons of not more than 5 mol %.
- 14. A process according to claim 2, further comprising subcooling the scrubbing agent prior to passing same into the column.
- 15. A process according to claim 2, further comprising withdrawing liquid from the distillation column at a point where the liquid is cooler than the bottoms liquid and cooling said scrubbing agent in indirect heat exchange relationship with said withdrawn liquid.
- 16. A process according to claim 1, wherein said gas comprising a mixture of hydrocarbons, prior to entering the distillation column, is cooled to form liquid and gaseous phases and both of said phases are fed to the distillation column.
- 17. A process according to claim 16, wherein said liquid and gaseous phases are fed separately to the distillation column.
- 18. A process according to claim 1, further comprising withdrawing a secondary gaseous fraction from the middle of the column, but below the lowermost feed point.
- 19. A process according to claim 18, further comprising subcooling the scrubbing agent prior to passing same into the column.
- 20. A process according to claim 18, wherein said overhead gaseous fraction comprises CH.sub.4 and C.sub.2 H.sub.6 and said second gaseous fraction comprises C.sub.3+ product.
- 21. A process according to claim 18, wherein said gas comprising a mixture of hydrocarbons further comprises CO.sub.2, said gaseous overhead fraction comprises CH.sub.4 and C.sub.2 hydrocarbons, and said second gaseous fraction comprises CO.sub.2.
- 22. A process according to claim 21, wherein said gas comprises a mixture of hydrocarbons containing more than 40 mol % CO.sub.2.
- 23. A process according to claim 1, further comprising subcooling the scrubbing agent prior to passing same into the column.
- 24. A process according to claim 23, further comprising withdrawing liquid from the distillation column at a point where the liquid is cooler than the bottoms liquid and cooling said scrubbing agent in indirect heat exchange relationship with said withdrawn liquid.
- 25. A process according to claim 23, wherein the hydrocarbon fraction to be scrubbed out is a C.sub.2 hydrocarbon fraction and the scrubbing agent is sub-cooled to a temperature of about 0.degree. C.
- 26. A process according to claim 1, further comprising subcooling the scrubbing agent prior to passing same into the column.
- 27. A process according to claim 1, wherein said gas comprises a mixture of hydrocarbons containing 0-40 mol % CH.sub.4 and inerts.
- 28. A process according to claim 1, wherein said gas comprises a mixture of hydrocarbons containing 0-20 mol % CH.sub.4 and inerts.
- 29. A process according to claim 1, wherein said scrubbing agent has a composition different than the hydrocarbon fraction which is scrubbed out of the gas mixture.
- 30. A process for the fractionation of a gas comprising a mixture of hydrocarbons and inerts in a distillation column having at least one feed point to produce a gaseous overhead fraction containing lighter hydrocarbons and a bottoms product fraction containing heavier hydrocarbons,
- the improvement comprising passing a physical scrubbing agent into an upper section of the column to scrub out a hydrocarbon fraction which would otherwise be withdrawn from the column in the gaseous overhead fraction and cooling said physical scrubbing agent prior to its delivery to the upper section of the column, said physical scrubbing agent being cooled by indirect heat exchange with a liquid withdrawn from the distillation column at a point where the liquid is cooler than the bottoms liquid.
Priority Claims (1)
Number |
Date |
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Kind |
3528071 |
Aug 1985 |
DEX |
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Parent Case Info
This application is a continuation of application Ser. No. 893,517 filed Aug. 5, 1986, now abandoned.
US Referenced Citations (5)
Continuations (1)
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Number |
Date |
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Parent |
893517 |
Aug 1986 |
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