IP Library › Granted Patent US 6,907,831
Granted Patent B1
US 6,907,831 · App. 10/733,744 · Granted Jun 21, 2005

Photolytic method of improving mercury capture in fossil (coal) fired systems

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Quick Facts
Patent No.
US 6,907,831
App. No.
10/733,744
Granted
Jun 21, 2005
Kind
B1
Abstract

A combustion-based system and related method includes a combustor for burning a combustible material, wherein an exhaust gas stream output by the combustor includes NO 2 and at least one metal including mercury. An ultraviolet light source is in optical communication with the exhaust gas stream. Ultraviolet light from the light source photochemically dissociates at least a portion of the NO 2 to form an NO 2 reduced exhaust stream. A sorbent containing filter media receives the NO 2 reduced exhaust stream and as a result of the reduction in NO 2 provides improved trapping efficiency of mercury.

Claims (22)

1. A combustion-based system, comprising:

a combustor for burning a combustible material, wherein an exhaust gas stream output by said combustor includes NO 2 and at least one metal including mercury;

at least one ultraviolet light source in optical communication with said exhaust gas stream, ultraviolet light from said light source photo-chemically dissociating at least a portion of said NO 2 to form an NO 2 reduced exhaust stream, and

a sorbent containing filter media for receiving said NO 2 reduced exhaust stream, said filter media trapping said at least one metal.

2. The system of claim 1 , wherein said system comprises a fossil fuel fired power plant.

3. The system of claim 1 , wherein said combustible material comprises coal.

4. The system of claim 1 , wherein said system comprises a waste incinerator.

5. The system of claim 1 , wherein said mercury in said exhaust stream is in the vapor phase.

6. The system of claim 1 , further comprising a particle collection device for trapping said sorbent.

7. The system of claim 1 , wherein said ultraviolet light source provides light in a wavelength range of 350 to 400 nm.

8. The system of claim 1 , wherein said system reduces an amount of NO 2 in said exhaust gas to below 20 parts per million.

9. The system of claim 1 , wherein said system reduces an amount of NO 2 in said exhaust gas to below 10 parts per million.

10. The system of claim 1 , wherein said system is exclusive of catalyst particles.

11. The system of claim 1 , wherein said sorbent media comprises activated carbon.

12. The system of claim 1 , wherein said light source is disposed in said exhaust gas stream.

13. The system of claim 1 , wherein said light source is disposed remote from said exhaust stream.

14. The system of claim 13 , wherein a optical fiber network transmits said ultraviolet light to said exhaust stream.

15. The method of claim 14 , wherein said ultraviolet light is in a wavelength range of 350 to 400 nm.

16. The method of claim 14 , wherein said exhaust gas stream is generated by combusting coal.

17. A method for reducing mercury emissions from combustion-based systems, comprising the steps of:

irradiating an exhaust gas stream including mercury and NO 2 with ultraviolet light, said light photo-chemically dissociating at least a portion of said NO 2 to form an NO 2 reduced gas stream, and

contacting said NO 2 reduced gas stream with a sorbent material, wherein said sorbent traps said mercury.