Separation device for carbon dioxide, method for the operation thereof, and separating unit

1. A device for separating off carbon dioxide, comprising:

an absorption unit,

a desorption unit assigned to the absorption unit, and

a separation unit for separating off salts from a scrubbing solution,

wherein the absorption unit and the desorption unit are connected to each other via a first conduit for a regenerated scrubbing solution and a second conduit for a loaded scrubbing solution,

wherein the separation unit comprises a crystallizer for forming salt crystals and a first separator unit on the downstream side thereof for separating off the salt crystals,

wherein the crystallizer comprises a crystallization chamber for forming the salt crystals and a classifying appliance, constructed as a countercurrent classifier, for separating the salt crystals according to their particle size,

wherein a first branch conduit is connected to the crystallization chamber, which first branch conduit opens out into the countercurrent classifier via a second separator unit, where this substream acts as a counterflow,

wherein the second separator unit is adapted to retain large and medium salt crystals, and

wherein the second separator unit is connected to the crystallization chamber via a conduit for supplying the retained salt crystals.

2. The device for separating off carbon dioxide as claimed in claim 1 , wherein the separation unit is connected into the first conduit.

3. The device for separating off carbon dioxide as claimed in claim 1 , wherein the second separator unit is constructed as a filter.

4. The device for separating off carbon dioxide as claimed in claim 1 , wherein the first separator unit comprises a centrifuge.

5. The device for separating off carbon dioxide as claimed in claim 1 , wherein a second branch conduit is connected to the crystallizer, which second branch conduit is returned back to the crystallizer via a comminution appliance.

6. The device for separating off carbon dioxide as claimed in claim 1 , wherein the device is adapted for separating off carbon dioxide from a flue gas of a fossil-fuelled power plant.

7. A method for separating off carbon dioxide, comprising:

a loaded scrubbing solution is conducted from an absorption unit to a desorption unit and a regenerated scrubbing solution is conducted from the desorption unit to the absorption unit,

the scrubbing solution is fed to a separation unit in which, by means of a crystallizer, salt crystals are formed in the scrubbing solution and are separated off by means of a downstream separator unit,

the salt crystals are formed in a crystallization chamber of the crystallizer and are separated according to their particle size in a classifying appliance of the crystallizer by means of a counterflow,

a first substream of the scrubbing solution is taken off from the crystallization chamber,

the first substream is fed as counterflow to the classifying appliance,

large and medium salt crystals situated in the first substream that has been taken off are retained, and

the retained salt crystals are fed via a separate conduit into the crystallization chamber.

8. The method for separating off carbon dioxide as claimed in claim 7 , wherein the method is adapted for separating off carbon dioxide from a flue gas of a fossil-fuelled power plant.

9. The method as claimed in claim 7 , wherein filtration is performed for separating off the salt crystals from the first substream.

10. The method as claimed in claim 7 , wherein centrifugation is performed for separating off the salt particles by means of the separator unit.

11. The method as claimed in claim 7 , wherein a second substream of the scrubbing solution is taken off from the crystallizer and salt crystals present in the second substream are comminuted, and wherein the second substream is returned back to the crystallizer.

12. A separation unit for separating off salts from a scrubbing solution used in a device for separating off carbon dioxide, comprising an absorption unit and a desorption unit assigned to the absorption unit, wherein the absorption unit and the desorption unit are connected to one another via a first conduit for a regenerated scrubbing solution and a second conduit for a loaded scrubbing solution,

wherein the separation unit comprises

a crystallizer for forming salt crystals, and

a first separator unit downstream thereof for separating off the salt crystals,

wherein the crystallizer comprises a crystallization chamber for forming the salt crystals and a classifying appliance, constructed as a countercurrent classifier, for separating the salt crystals according to their particle size,

wherein a first branch conduit is connected to the crystallization chamber, which first branch conduit opens out into the countercurrent classifier via a second separator unit, where this substream acts as counterflow, and

wherein the second separator unit is connected via a conduit to the crystallization chamber for supplying salt crystals which are separated off.

13. The separation unit as claimed in claim 12 , wherein the second separator unit is constructed as a filter.

14. The separation unit as claimed in claim 12 , wherein the first separator unit comprises a centrifuge.

15. The separation unit as claimed in claim 12 , wherein a second branch conduit is connected to the crystallizer, which second branch conduit is returned back to the crystallizer via a comminution appliance.