Butadiene extraction process

Patent metadata

Field	Value
Publication number	US-9296667-B2
Application number	US-201314058637-A
Country	US
Kind code	B2
Filing date	Oct 21, 2013
Priority date	Oct 30, 2012
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

A process for recovering 1,3-butadiene from a C 4 fraction, where the butadiene extraction processes may be operated at an intermediate pressure using a liquid ring type compressor. The use of a liquid ring compressor, among other process options presented herein, may advantageously reduce capital and operating costs, similar to the compressorless option, while mitigating the risks associated with the higher operating temperatures and pressures associated with the compressorless option. Thus, the embodiments of the processes disclosed herein encompass the best features of the conventional design (low pressure, with a compressor) with the advantages of the compressorless design (low capital and operating cost), as well as other advantages unique to the systems disclosed herein.

First claim

What is claimed:

1. A process for recovering 1,3-butadiene from a C 4 fraction, comprising:
feeding a hydrocarbon fraction containing butanes, butenes, 1,2-butadiene, 1,3-butadiene, C 4 acetylenes, C 3 acetylenes, and C 5+ hydrocarbons to an extractive distillation system;
contacting the hydrocarbon fraction with a solvent in the extractive distillation system to selectively dissolve a portion of the hydrocarbon fraction;
recovering a vapor fraction comprising a first portion of the butanes and the butenes from the extractive distillation system;
recovering an enriched solvent fraction comprising the 1,3-butadiene, the 1,2-butadiene, C 4 acetylenes, C 3 acetylenes, C 5+ hydrocarbons, and a second portion of the butanes and the butenes;
feeding the enriched solvent fraction to a rectifier to at least partially degas the enriched solvent;
recovering a second portion of the butanes and butenes from the rectifier as an overheads fraction;
recovering the C 3 and C 4 acetylenes, 1,3-butadiene, 1,2-butadiene, and C 5+ hydrocarbons from the rectifier as a side draw fraction;
recovering a partially degassed solvent comprising 1,2-butadiene and C 4 acetylenes from the rectifier as a bottoms fraction;
feeding at least a portion of the partially degassed solvent to a degasser to further degas the solvent;
recovering an overheads fraction comprising at least one of C 4 acetylenes and 1,2-butadiene from the degasser;
recovering a side draw fraction comprising the C 4 acetylenes from the degasser;
recovering a bottoms fraction comprising degassed solvent from the degasser;
compressing the degasser overheads fraction using a liquid ring compressor; and
recycling at least a portion of the compressed degasser overheads fraction to the rectifier.

2. The process of claim 1 , further comprising phase separating the compressed degasser overheads fraction to recover a condensate fraction and recycling at least a portion of the condensate fraction to the liquid ring compressor.

3. The process of claim 1 , further comprising:
heating the partially degassed solvent via indirect heat exchange to vaporize at least a portion of the dissolved 1,2-butadiene and/or C 4 acetylenes;
feeding the heated partially degassed solvent to a degasser feed drum to phase separate the vaporized portion of the 1,2-butadiene and/or C 4 acetylenes from the heated partially degassed solvent;
recovering a vapor phase from the degasser feed drum comprising at least one of 1,2-butadiene and C 4 acetylenes;
recovering a liquid phase from the degasser feed drum;
feeding the liquid phase from the degasser feed drum to the degasser as the at least a portion of the partially degassed solvent.

4. The process of claim 3 , wherein the degasser feed drum and the degasser are integral.

5. The process of claim 3 , further comprising admixing the vapor phase recovered from the degasser feed drum and the at least a portion of the compressed degasser overheads and recycling the combined portion to the rectifier.

6. The process of claim 5 , wherein a ratio of the at least a portion of the compressed degasser overheads to the vapor phase is in a range from about 0.1:1 to 1:1.

7. The process of claim 3 , wherein the degasser feed drum operates at a pressure in the range from about 3.5 to about 5.5 kg/cm 2 gage and a temperature in the range from about 120° C. to about 140° C.

8. The process of claim 7 , wherein the degasser pressure is greater than an operating pressure of the rectifier.

9. The process of claim 3 , wherein the heating the partially degassed solvent via indirect heat exchange comprises at least one of:
contacting the partially degassed solvent with the degasser bottoms fraction via indirect heat exchange; and
contacting the partially degassed solvent with a heat exchange medium comprising at least one of a synthetic organic heat transfer fluid, water, and steam.

10. The process of claim 9 , wherein a heat exchanger(s) for contacting the partially degassed solvent comprises a suppressed vaporization heater.

11. The process of claim 1 , wherein the degasser operates at an overhead pressure in the range from about 1.5 to about 3.5 kg/cm 2 gage and an overhead temperature in the range from about 110° C. to about 140° C.

12. The process of claim 11 , wherein the degasser operates at a bottoms pressure in the range from about 160° C. to about 190° C.

13. The process of claim 1 , wherein the rectifier operates at an overhead pressure in the range from about 3 to about 5 kg/cm 2 gage and an overhead temperature in the range from about 50° C. to about 70° C.

14. The process of claim 13 , wherein the rectifier operates at a bottoms temperature in the range from about 70° C. to about 100° C.

15. The process of claim 14 , wherein heat is supplied to the rectifier via indirect heat exchange in a reboiler using a heating medium having a temperature of less than 130° C.

16. The process of claim 15 , wherein the reboiler comprises a single pass heat exchanger.

17. The process of claim 16 , wherein a process-side temperature increase across the reboiler is in the range from about 5° C. to about 15° C.

18. The process of claim 17 , wherein a percent vaporization across the reboiler is in the range from about 3 wt. % to about 9 wt. %.

Assignees

• Lummus Technology Inc

Inventors

• Schwint Kevin John
• Brummer Robert J

Classifications

• B01D3/40 Primary

  Extractive distillation · CPC title

• B01D19/0068

  General arrangements, e.g. flowsheets (B01D19/0063 takes precedence) · CPC title

• C07C11/167

  1, 3-Butadiene · CPC title

• C07C7/08 Primary

  by extractive distillation · CPC title

• B01D3/143

  by two or more of a fractionation, separation or rectification step · CPC title