Method and device for separating carbon dioxide from a gas stream and for removing degradation products in the washing medium by photolytic decomposition
A method for separating carbon dioxide from a gas stream, in particular from a flue gas stream, wherein, a gas stream is brought into contact with a washing medium in an absorber of a separation device and the carbon dioxide contained in the gas stream is separated; the charged washing medium is supplied to a desorber of the separation device to release the carbon dioxide; a vapor stream is removed from the desorber and is supplied to a cooling unit to form a condensate; degradation products, in particular nitrosamines, contained in at least a partial stream of the condensate are photolytically decomposed to decomposition products; at least the decomposition products, in particular nitrites and amines, are removed; and at least a partial stream of the condensate is returned to the desorber. A corresponding separation device separates carbon dioxide from a gas stream.
1. A method for separating carbon dioxide from a gas stream, the method comprising:
bringing into contact a gas stream in an absorber of a separation device with a washing medium and separating the carbon dioxide contained in the gas stream in the absorber of the separation device, wherein an amino acid salt solution is used as a washing medium,
supplying the charged washing medium, in order to release the carbon dioxide to a desorber of the separation device,
removing a vapor stream from the desorber and supplying the vapor stream to a cooling unit to form a condensate,
photolytically decomposing degradation products contained in at least a partial stream of the condensate to decomposition products,
removing at least the decomposition products, and
returning at least a partial stream of the condensate to the desorber,
wherein a first partial stream of the charged washing medium from the absorber is supplied to a first desorber stage of the desorber without preheating, and a second partial stream of the charged washing medium from the absorber is supplied to a second desorber stage of the desorber.
2. The method of claim 1 , wherein the degradation products are photolytically decomposed by UV radiation.
3. The method of claim 1 , wherein the at least a partial stream of the condensate is removed, and wherein the degradation products contained in the removed partial stream are photolytically decomposed to the decomposition products.
4. The method of claim 3 , wherein the removed partial stream is replaced by fresh water.
5. The method of claim 1 , wherein the decomposition products are removed together with the condensate supplied to a recovery facility.
6. The method of claim 1 , wherein the decomposition products are separated from the condensate in a processing unit.
7. The method of claim 6 , wherein the decomposition products separated from the condensate in the processing unit are supplied to a recovery facility.
8. The method of claim 6 , wherein the purified condensate is returned from the processing unit to the desorber.
9. The method of claim 1 , wherein the decomposition products are separated from the condensate by means of reverse osmosis.
10. The method of claim 1 , wherein washing medium discharged from the desorber is supplied to a pressure vessel.
11. The method of claim 10 , wherein a second partial stream of the washing medium is supplied from the pressure vessel to the absorber.
12. The method of claim 10 , wherein a first partial stream of the washing medium is supplied from the pressure vessel to the desorber.
13. The method of claim 12 , wherein degradation products contained in the washing medium are photolytically decomposed to decomposition products.
14. The method of claim 13 , wherein washing medium which has been purified of decomposition products is supplied to the desorber.
15. The method of claim 13 , wherein the degradation products comprise nitrosamines.
16. The method of claim 1 , wherein washing medium from the desorber is at least partially supplied to a reboiler.
17. The method of claim 1 , wherein the degradation products comprise nitrosamines and the decomposition products comprise nitrites and amines.
18. The method of claim 1 , wherein the second partial stream is supplied to the second desorber stage of the desorber preheated.
19. A separation device for separating carbon dioxide from a gas stream, comprising
an absorber for separating carbon dioxide from the gas stream by means of an amino acid salt solution as a washing medium,
a desorber fluid-dynamically coupled to the absorber for releasing carbon dioxide absorbed in the washing medium,
a cooling unit fluid-dynamically connected to the desorber to form a condensate from a vapor stream which is removable from the desorber,
a branch point arranged between the cooling unit and the desorber for at least a partial stream of the condensate, and
a radiation source for photolytic decomposition of degradation products contained in the condensate,
wherein the radiation source is fluid-dynamically connected upstream and/or downstream from the branch point, and
wherein the absorber is fluid-dynamically connected to a first desorber stage of the desorber via a discharge line, and a branch line is fluid-dynamically connected to the discharge line and a second desorber stage of the desorber,
wherein a first partial stream of charged washing medium from the absorber is supplied to the first desorber stage without preheating via the discharge line, and a second partial stream of charged washing medium from the absorber is supplied to the second desorber stage via the branch line.
20. The separation device of claim 19 , wherein the radiation source is a UV radiation source.
21. The separation device of claim 19 , wherein the radiation source configured downstream from the branch point is connected to a condensate discharge line.
22. The separation device of claim 21 , wherein the condensate discharge line is fluid-dynamically connected to a removal line for removing decomposition products formed by photolytic decomposition of the degradation products in the condensate, said removal line leading to a recovery facility.
23. The separation device of claim 22 , wherein the decomposition products comprise nitrites and amines.
24. The separation device of claim 19 , wherein the radiation source configured upstream from the branch point is connected to a condensate return line.
25. The separation device of claim 24 , wherein a fresh water line is fluid-dynamically connected to the condensate return line.
26. The separation device of claim 19 , wherein a processing unit for separating the decomposition products from the condensate is fluid-dynamically configured downstream from the radiation source.
27. The separation device of claim 26 , wherein the branch point for removing the decomposition products separated from the condensate is configured in the processing unit.
28. The separation device of claim 26 , wherein the processing unit comprises a reverse osmosis system.
29. The separation device of claim 26 , wherein a removal line for removing the separated decomposition products is connected to the processing unit, said removal line leading to a recovery facility.
30. The separation device of claim 29 , further comprising a heat exchanger fluid-dynamically connected to the branch line and configured to preheat washing medium enroute to the second desorber stage.
31. The separation device of claim 29 , wherein the decomposition products comprise nitrites and amines.
32. The separation device of claim 19 , wherein the desorber is connected to a pressure vessel via a discharge line.
33. The separation device of claim 32 , wherein the pressure vessel is fluid-dynamically connected to the desorber via a discharge line.
34. The separation device of claim 33 , wherein a UV radiation source is arranged on the discharge line of the pressure vessel.
35. The separation device of claim 32 , wherein the pressure vessel is fluid-dynamically connected to the absorber via a further discharge line.
36. The separation device of claim 19 , wherein a reboiler is connected to the desorber.
37. The separation device of claim 19 , wherein the degradation products comprise nitrosamines.