Treatment system and method for a flue gas from a combustion process

1. A treatment system for a flue gas from a combustion process comprising

a condenser,

a compressor for compressing the flue gas deprived of moisture at the condenser,

a NO 2 scrubber column supplied with the compressed flue gas from the compressor,

a liquid supply line for supplying at least a part of the liquid condensed at the condenser to the NO 2 scrubber column, and

a liquid recirculation line for recirculating at least a part of the liquid from the NO 2 scrubber column to the condenser.

2. The system according to claim 1 , further comprising a feed pump for supplying liquid to the NO 2 scrubber column, and

a controller for regulating the feed pump on the basis of at least a feature of the liquid supplied to the NO 2 scrubber column.

3. The system according to claim 2 , further comprising at least a sensor for the pH of the liquid supplied to the NO 2 scrubber column.

4. The system according to claim 3 , wherein the controller controls the feed pump in order to keep the pH of the liquid supplied to the NO 2 scrubber column in the range 5.5-7 and preferably 6-7.

5. The system according to claim 1 , further comprising a heat exchanger for cooling the liquid supplied to the NO 2 scrubber column.

6. The system according to claim 5 , wherein the heat exchanger is on the liquid supply line.

7. A treatment method for a flue gas from a combustion process comprising

passing the flue gas through a condenser to condensate moisture contained therein,

compressing the flue gas deprived of moisture at a condenser,

passing the compressed flue gas through a NO 2 scrubber column to remove NO 2 ,

supplying at least a part of the liquid condensed at the condenser to the NO 2 scrubber column, and

recirculating at least a part of the liquid from the NO 2 scrubber column to the condenser.

8. The method according to claim 7 , further comprising regulating the supplying of at least a part of the liquid condensed at the condenser to the NO 2 scrubber column on the basis of at least a feature of the liquid supplied to the NO 2 scrubber column.

9. The method according to claim 8 , wherein the at least a feature of the liquid supplied to the NO 2 scrubber column is the pH.

10. The method according to claim 9 , further comprising regulating the feeding in order to keep the pH of the liquid supplied to the NO 2 scrubber column in the range 5.5-7 and preferably 6-7.

11. The method according to claim 7 , further comprising cooling the liquid supplied to the NO 2 scrubber column.

12. The method according to claim 11 , further comprising cooling the liquid supplied through the liquid supply line.