Separation of organic mixtures using gas separation or pervaporation and dephlegmation
View Patent ↗A process for treating mixtures of organic components, including azeotropic mixtures. The process includes a gas- or liquid-phase membrane separation step in conjunction with a dephlegmation step to treat at least a portion of the permeate vapor from the pervaporation step. The process yields a membrane residue stream, a stream enriched in the more volatile component as the overhead stream from the dephlegmator and a condensate stream enriched in the less volatile component as a bottoms stream from the dephlegmator. Any of these may be the principal product of the process.
1. A process for treating a mixture of two or more organic compounds, the process comprising:
(a) performing a membrane separation step by:
(i) providing a membrane having a feed side and a permeate side;
(ii) providing a driving force for transmembrane permeation;
(iii) passing the mixture as a feed fluid stream across the feed side;
(iii) withdrawing a residue fluid stream from the feed side;
(iv) withdrawing from the permeate side a permeate vapor stream enriched in at least one organic compound compared with the feed fluid stream;
(b) providing a dephlegmator having a coolant flow side and a gas stream flow side and adapted for partial condensation of a gas stream by providing countercurrent flow between the rising gas stream and a falling condensate stream;
(c) passing at least a portion of the permeate vapor stream into the dephlegmator as a feed gas stream;
(d) flowing a coolant across the coolant flow side in heat-exchanging relationship with the feed gas stream;
(e) withdrawing an overhead vapor stream from the dephlegmator;
(f) withdrawing a bottoms condensate stream from the dephlegmator.
2. The process of claim 1 , wherein the feed fluid stream is in the liquid phase.
3. The process of claim 1 , wherein the feed fluid stream is in the gas phase.
4. The process of claim 1 , wherein the membrane separation step (a) is carried out as a pervaporation step.
5. The process of claim 1 , wherein the membrane separation step (a) is carried out as a membrane distillation step.
6. The process of claim 1 , wherein the membrane separation step (a) is carried out as a vapor separation step.
7. The process of claim 1 , wherein the mixture comprises an azeotrope.
8. The process of claim 1 , wherein the mixture comprises an aromatic compound and an aliphatic compound.
9. The process of claim 1 , wherein the mixture comprises an organic compound selected from the group consisting of alcohols, aldehydes, ketones, ethers and esters.
10. The process of claim 1 , wherein the mixture comprises multiple isomers of an organic compound.
11. The process of claim 1 , wherein the mixture comprises a C 4-6 hydrocarbon.
12. The process of claim 1 , wherein the mixture comprises an olefin and a paraffin.
13. The process of claim 1 , wherein the mixture comprises a sulfur-containing compound.
14. The process of claim 1 , wherein the mixture comprises a flavor compound.
15. The process of claim 1 , wherein the mixture further comprises a minor amount of an inorganic component.
16. The process of claim 1 , wherein the feed fluid stream is heated prior to passing across the feed side.
17. The process of claim 1 , wherein the feed fluid stream is compressed prior to passing across the feed side.
18. The process of claim 1 , wherein the membrane is a polymeric membrane.
19. The process of claim 1 , wherein the membrane is an inorganic membrane.
20. The process of claim 1 , wherein the dephlegmator is a shell-and-tube dephlegmator.
21. The process of claim 1 , wherein the dephlegmator is a plate-fin dephlegmator.
22. The process of claim 1 , wherein the dephlegmator includes at least a section containing structured packing.
23. The process of claim 1 , wherein the coolant is water.
24. The process of claim 1 , carried out to recover a desired organic compound and wherein the overhead vapor stream contains at least about 90 wt % of the desired organic compound.
25. The process of claim 1 , carried out to recover a desired organic compound and wherein the bottoms condensate stream contains at least about 90 wt % of the desired organic compound.
26. The process of claim 1 , carried out to recover a desired organic compound and wherein the residue fluid stream contains at least about 90 wt % of the desired organic compound.
27. The process of claim 1 , further comprising drawing a partial vacuum on the permeate side by means of a vacuum pump.
28. The process of claim 1 , wherein the driving force is provided without using a vacuum pump on the permeate side.
29. The process of claim 1 , further comprising passing a sweep gas across the permeate side.
30. The process of claim 1 , wherein the feed gas stream is at a higher pressure than the permeate vapor stream.
31. The process of claim 1 , further comprising condensing the overhead vapor stream to form a liquid product.
32. The process of claim 1 , further comprising subjecting the overhead vapor stream to additional purification by passing at least a portion of the overhead vapor stream to a further treatment step selected from the group consisting of pervaporation, dephlegmation, distillation, condensation, phase separation, evaporation, stripping, scrubbing, absorption and adsorption.
33. The process of claim 1 , further comprising subjecting the overhead vapor stream to additional purification by distillation.
34. The process of claim 1 , further comprising subjecting the overhead vapor stream to additional purification by pervaporation.
35. The process of claim 1 , further comprising subjecting the overhead vapor stream to additional purification by dephlegmation.
36. The process of claim 1 , further comprising recirculating at least a portion of the overhead vapor stream as additional feed fluid to step (a).
37. The process of claim 1 , further comprising subjecting the bottoms condensate stream to additional purification by passing at least a portion of the bottoms condensate stream to a further treatment step selected from the group consisting of pervaporation, dephlegmation, distillation, phase separation, evaporation, stripping, scrubbing, absorption and adsorption.
38. The process of claim 1 , further comprising subjecting the bottoms condensate stream to additional purification by distillation.
39. The process of claim 1 , further comprising subjecting the bottoms condensate stream to additional purification by pervaporation.
40. The process of claim 1 , further comprising recirculating at least a portion of the bottoms condensate stream as additional feed fluid to step (a).
41. The process of claim 1 , further comprising subjecting the residue fluid stream to additional purification by passing at least a portion of the residue fluid stream to a further treatment step selected from the group consisting of pervaporation, dephlegmation, distillation, evaporation, condensation, phase separation, stripping, scrubbing, absorption and adsorption.
42. The process of claim 1 , further comprising subjecting the residue fluid stream to additional purification by distillation.
43. The process of claim 1 , further comprising subjecting the residue fluid stream to additional purification by pervaporation.
44. The process of claim 1 , further comprising subjecting the residue fluid stream to additional purification by dephlegmation.
45. The process of claim 1 , wherein the permeate vapor stream is enriched in the at least one organic compound by no more than about 10-fold compared with the feed fluid stream.
46. The process of claim 1 , wherein the membrane separation step (a) is carried out in multiple sub-steps connected in such a way that a previous residue stream from a previous sub-step forms a next feed stream to a next sub-step and each sub-step results in a sub-step permeate vapor stream, and in which at least two of the sub-step permeate vapor streams are combined to form the permeate vapor stream.
47. The process of claim 46 , wherein each next feed stream is heated prior to passing into each next sub-step.