Patent EA-004519-B1 (EA)
Title: Process for gas recovery
Inventor: MAK JOHN
IPC: F25J3/02
Filed: 2001-06-27
Abstract: 1. A process for gas recovery comprising: providing a feedstock into a refluxed absorber operating at a first pressure, producing a bottoms product stream in the absorber and feeding the bottoms product stream into a distillation column fluidly coupled to the absorber, providing a feedstock into the distillation column, the distillation column is operated at a second pressure that is at least 100 psi lower than the first pressure, producing a distillation column overhead stream, wherein the distillation column overhead stream is separated into a gaseous portion that is liquefied and provides the absorber reflux stream and a fluid portion that provides reflux for the distillation column, wherein at least a portion of the bottoms product stream is expanded and provides cooling for at least one of the absorber reflux stream and the distillation column feed stream. 2. The process of claim 1 wherein the distillation column comprises a de ethanizer column. 3. The process of claim 2 wherein the feedstock is at a pressure of between 1000 psig and 2000 psig. 4. The process of claim 3 wherein at least a portion of the feedstock is expanded in a turboexpander. 5. The process of claim 3 wherein the bottoms product stream has a pressure and wherein expanding the bottoms product stream reduces the bottoms product stream pressure in a range of 100-250 psi. 6. The process of claim 3 wherein the expanded bottoms product stream has a temperature between -95 degree F to -125 degree F. 7. The process of claim 3 wherein the expanded absorber bottoms product stream is fed as the distillation column feed stream into the distillation column at a position that is at least three trays below an upmost tray of the distillation column. 8. The process of claim 3 wherein the expanded bottoms product stream further provides cooling for a distillation column overhead stream. 9. The process of claim 3 wherein the distillation column produces a distillation column overhead stream that is compressed, cooled, and fed into the absorber as the absorber reflux stream. 10. The process of claim 3 wherein the feedstock comprises propane, and wherein the distillation column produces a distillation column product stream that comprises at least 95% of the propane in the feedstock. 11. The process of claim 2 wherein the feedstock is at a pressure of between 550 psig and 800 psig. 12. The process of claim 11 wherein the feedstock is fed into the absorber without passing through a turboexpander. 13. The process of claim 11 wherein the bottoms product stream has a pressure and wherein expanding the bottoms product stream reduces the bottoms product stream pressure in a range of 100-250 psi. 14. The process of claim 11 wherein the bottoms product stream has a temperature between-50 degree F to-70 degree F. 15. The process of claim 11 wherein the expanded bottoms product stream is fed as the distillation column feed stream into the distillation column at a position that is at least three trays below an upmost tray in the distillation column. 16. The process of claim 11 wherein at least a portion of the feedstock is fed into a lower section of the distillation column. 17. The process of claim 11 further comprising an external refrigeration coupled to the distillation column. 18. The process of claim 1 wherein the distillation column comprises a demethanizer. 19. The process of claim 18 wherein the feedstock is at a pressure of between1000 psig and 2000 psig. 20. The process of claim 18 wherein at least a portion of the feedstock is expanded in a turboexpander. 21. The process of claim 18 wherein the bottoms product stream has a pressure and wherein expanding the bottoms product stream reduces the bottoms product stream pressure in a range of 100-250 psi. 22. The process of claim 18 wherein the expanded bottoms product stream has a temperaturebetween-95 degree F to-125 degree F. 23. The process of claim 18 wherein the expanded bottoms product stream is fed as the distillation column feed stream into the distillation column. 24. The process of claim 18 wherein the distillation column produces a methane rich distillation column overhead stream that is compressed, cooled, and fed into the absorber as the absorber reflux stream. 25. The process of claim 18 wherein the distillation column produces a distillation column product stream that comprises no more than 500 ppm carbon dioxide. 26. The process of claim 18 wherein the feedstock is split into a first portion and a second portion, and wherein an external refrigeration cools at least part of the first portion. 27. The process of claim 26 further comprising at least one side reboiler coupled to the distillation column, wherein the at least one side reboiler is fluidly coupled to the demethanizer between a top tray and a position eight trays below the top tray, provides heat duty for stripping CO2 from a demethanizer product stream, provides reboiling of the distillation column, and further provides cooling of the first portion of the feedstock. 28. The process of claim 1, wherein the absorber and the distillation column are configured into a single tower configuration.