Apparatus and method for the removal of contaminants in gases

• US 6,136,072 A
• Filed: 12/21/1998
• Issued: 10/24/2000
• Est. Priority Date: 01/20/1998
• Status: Expired due to Fees

• Current Assignee: Electric Power Research Institute Incorporated
• Original Assignee: Electric Power Research Institute Incorporated
• Inventors: Sjostrom, Sharon, Chang, Ramsay
• Primary Examiner(s): SMITH, DUANE
• Application Number:
  US09/218,802
• Time in Patent Office: 673 Days
• Field of Search: 95/134, 95/133, 95/148, 95/280, 55/285, 55/302, 96/134, 96/135, 96/140, 96/141, 96/143, 96/144, 96/146, 96/154
• US Class Current: 95/134
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 2259/40096 by using electrical resistance heating
• CPC Class Codes: B01D 53/04 with stationary adsorbents B01D53/025 takes precedence
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: F23J 15/02 of purifiers, e.g. for removing noxious material traps for solid residues F23J3/04
• CPC Class Codes: F23J 2215/60 Heavy metals; Compounds thereof
• CPC Class Codes: F23J 2219/60 Sorption with dry devices, e.g. beds

Abstract

An apparatus and method are described for removing vapor phase contaminants from a gas stream by placing a porous element having a sorbent material into ductwork through which the gas stream passes. In a first mode of operation, vapor phase contaminants are adsorbed by the sorbent. In a second mode of operation, the porous element is cleaned of any accumulated deposits, for example fly ash, while in place without having to stop the gas flow. In a third mode of operation, the sorbent can be regenerated in place and without having to stop the gas flow by heating and collecting the desorbed contaminants. This invention is particularly suited for the removal of vapor phase mercury from flue gas generated by a combustion process.

Claims

1. An apparatus for removing a vapor phase contaminant from a gas stream, said apparatus comprising:

a duct through which a gas stream is passed;

a porous hollow element having a sorbent material connected to said duct and extending into the interior of said duct;

a heating supply connected to said porous hollow element;

a cleaning gas supply connected to said porous hollow element; and

an exhaust system connected to said porous hollow element.

2. The apparatus of claim 1 wherein said porous hollow element is coated with said sorbent material.

3. The apparatus of claim 1 wherein said porous hollow element is substantially composed of said sorbent material.

4. The apparatus of claim 1 wherein said sorbent material is selected from the group consisting of activated carbon, silver, selenium and gold.

5. The apparatus of claim 1 wherein said heating supply comprises a power supply in direct electrical connection with said porous hollow element.

6. The apparatus of claim 1 wherein said heating supply comprises a source of microwave energy directed to said porous hollow element.

7. The apparatus of claim 1 wherein said cleaning gas supply comprises a uniform reverse gas flow.

8. The apparatus of claim 1 wherein said cleaning gas supply comprises a pulse gas supply.

9. The apparatus of claim 1 wherein said exhaust system comprises a condenser.

10. The apparatus of claim 1 wherein said exhaust system comprises an absorber.

11. The apparatus of claim 1 wherein said porous hollow element is shaped like a tube.

12. The apparatus of claim 1 wherein said porous hollow element is shaped like a plate.

13. A method for removing a vapor phase contaminant from a gas stream in a duct, said method comprising the steps of:

adsorbing a vapor phase contaminant onto a sorbent material on a porous hollow element;

cleaning said porous hollow element while the gas stream continues to flow in the duct;

regenerating said sorbent material while the gas stream continues to flow in the duct by heating said sorbent material and passing a portion of the gas stream into the interior of said porous hollow element and out of the duct; and

collecting said vapor phase contaminant from said portion of the gas stream.

14. The method of claim 13 wherein said cleaning step includes the step of cleaning said porous hollow element by passing a cleaning gas from the exterior of the duct to the interior of said porous hollow element and through the wall of said porous hollow element into the duct.

15. The method of claim 14 wherein said cleaning step includes the step of cleaning said porous hollow element by passing a cleaning gas in pulses from the exterior of the duct to the interior of said porous hollow element and through the wall of said porous hollow element into the duct.

16. The method of claim 13 wherein said regenerating step includes the step of regenerating said sorbent material by heating said sorbent material electrically.

17. The method of claim 13 wherein said regenerating step includes the step of regenerating said sorbent material by heating said sorbent material by directing microwave energy to said porous hollow element.

18. The method of claim 13 wherein said collecting step includes the step of collecting said vapor phase contaminant by condensing said vapor phase contaminant.

19. The method of claim 13 wherein said collecting step includes the step of collecting said vapor phase contaminant by absorbing said vapor phase contaminant.