System and method for decomposing ammonia from fly ash
View Patent ↗A system and method for decomposing ammonia from fly ash contaminated with ammonia is provided which includes maintaining the temperature of a bed of ammonia-contaminated fly ash at a decomposition temperature greater than 500° F. and less than 842° F. to decompose the ammonia from the fly ash. In a preferred embodiment, the ammonia-laden fly ash is maintained at a temperature less than a lowest carbon combustion temperature at which substantial combustion of carbon in fly ash begins to occur. A preferred embodiment includes a first chamber operating at a decomposition temperature greater than 500° F. and less than 842° F. followed by a second chamber operating at a higher carbon combustion temperature for carbon burn-out.
1. A method of removing ammonia from fly ash, the method comprising:
providing a chamber;
providing a supply of ammonia-laden fly ash;
introducing the supply of ammonia-laden fly ash into the chamber at a temperature below 800° F.;
fluidizing the supply of ammonia-laden fly ash;
maintaining the supply of ammonia-laden fly ash at a decomposition temperature greater than 500° F. and less than 800° F. to decompose the ammonia in the ammonia-laden fly ash; and
removing the resultant ammonia-free fly ash from the chamber.
2. The method of claim 1 , further comprising:
providing a second chamber;
introducing the resultant ammonia-free fly ash into the second chamber;
increasing the temperature of the resultant ammonia-free fly ash to a carbon combustion temperature at which substantial combustion of carbon in the fly ash occurs;
fluidizing the resultant ammonia-free fly ash; and
maintaining the resultant ammonia-free fly ash at the carbon combustion temperature to remove the carbon from the fly ash.
3. The method of claim 1 , wherein the step of maintaining the supply of ammonia-laden fly ash at a decomposition temperature greater than 500° F. and less than 800° F. to decompose the ammonia in the ammonia-laden fly ash further includes maintaining the ammonia-laden fly ash at a temperature less than a lowest carbon combustion temperature at which combustion of carbon in fly ash begins to occur.
4. The method of claim 1 , wherein the temperature of the supply of ammonia-laden fly ash is controlled by a temperature control unit.
5. The method of claim 4 , wherein the temperature control unit comprises a controller, a thermocouple, and a heat source.
6. The method of claim 5 , wherein the heat source is selected from a group consisting of: hot fly ash, hot exhaust gas, a heated air input, a liquefied petroleum gas burner and a natural gas burner.
7. The method of claim 1 , wherein the resultant ammonia-free fly ash has an ammonia concentration of less than 60 ppm.
8. The method of claim 1 , wherein the resultant ammonia-free fly ash has an ammonia concentration of less than 40 ppm.
9. The method in claim 1 , wherein a resultant flue gas contains less than 1% of the ammonia introduced into the system.
10. The method of claim 1 , wherein less than 1% of the ammonia introduced into the system forms NO x .
11. The method of claim 2 , wherein the temperature of the supply of ammonia-laden fly ash is controlled by a temperature control unit including a heat source selected from a group consisting of: hot fly ash, hot exhaust gas, a heated air input, a liquefied petroleum gas burner and a natural gas burner.
12. The method of claim 2 , wherein less than 1% of the ammonia introduced into the system forms NO x .