Reduced liquid discharge in wet flue gas desulfurization

1. A method for removing contaminants from a flue gas stream, the method comprising:

removing fly ash from a flue gas stream utilizing a particle collector;

contacting the flue gas stream with an alkaline reagent in a wet scrubber;

discharging a purge liquid from the wet scrubber; and

combining at least a portion of the purge liquid with at least a portion of fly ash circulating within a dry circulating fluid bed scrubber (CDS) to form moistened fly ash, whereby the moistened fly ash removes at least a portion of contaminants present in the flue gas stream.

2. A method according to claim 1 , wherein after discharging the purge liquid from the wet scrubber particles present in said purge liquid are removed therefrom or reduced, before combining at least a portion of the purge liquid with at least a portion of the fly ash.

3. A method according to claim 1 , wherein the particle collector is one of a bag house, an electrostatic precipitator and a fabric filter.

4. A method according to claim 1 wherein said alkaline reagent is selected from one of lime and limestone.

5. A method according to claim 1 wherein said purge liquid comprises water.

6. A method according to claim 1 wherein the portion of fly ash is present in the moistened fly ash in an amount of between about 94% to about 98% by weight based on the total weight of the moistened fly ash.

7. A method according to claim 6 wherein the portion of fly ash is present in the moistened fly ash in an amount of between about 94% to about 95% by weight based on the total weight of the moistened fly ash.

8. A method according to claim 1 wherein the portion of fly ash is present in the moistened fly ash in an amount of between about 30% to about 50% by weight based on the total weight of the moistened fly ash.

9. A method according to claim 1 , wherein the contaminants comprise SOx, Hel, and acidic gases.

10. A method of reusing an amount of purge liquid in a flue gas stream treatment system, the method comprising the steps of:

removing fly ash from a flue gas stream and transporting the fly ash to a dry circulating fluid bed scrubber (CDS); and

combining at least a portion of the purge liquid with at least a portion of fly ash circulating within the CDS to form moistened fly ash.

11. A method according to claim 10 wherein removing the fly ash from the flue gas stream comprises introducing the flue gas stream to a particle collector.

12. A method according to claim 10 wherein the moistened fly ash reacts with the flue gas stream so as to remove at least a portion of contaminants present in the flue gas stream.

13. A system for reducing or eliminating an amount of purge liquid sent to a wastewater treatment plant in a flue gas treatment system, the system comprising:

means for removing fly ash from a flue gas stream and diverting the fly ash to a dry circulating fluid bed scrubber (CDS);

means for discharging a purge liquid from a wet scrubber and diverting the purge liquid to the CDS; and

means for combining at least a portion of the purge liquid with at least a portion of fly ash circulating within the CDS to form a moistened fly ash and whereby the moistened fly ash removes at least a portion of contaminants present in the flue gas stream.

14. A system according to claim 13 wherein the purge liquid comprises water.

15. A system according to claim 13 wherein the means for removing fly ash from a flue gas stream is one of a bag house, an electrostatic precipitator and a fabric filter.

16. A system according to claim 13 wherein the means for combining the removed fly ash with at least a portion of the purge liquid to form a moistened fly ash comprises a dry circulating bed scrubber (CDS).