Low NOX gas combustion systems

• US 5,431,557 A
• Filed: 12/16/1993
• Issued: 07/11/1995
• Est. Priority Date: 12/16/1993
• Status: Expired due to Fees

• Current Assignee: Laars, Inc.
• Original Assignee: Teledyne Industries Incorporated (Teledyne Technologies Incorporated)
• Inventors: Hamos, Robert E.
• Primary Examiner(s): Price, Carl D.
• Application Number:
  US08/167,155
• Time in Patent Office: 572 Days
• Field of Search: 431/7, 431/12, 431/326, 431/328, 431/329
• US Class Current: 431/7
• CPC Class Codes: F23D 14/02 Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
• CPC Class Codes: F23D 14/16 using permeable blocks
• CPC Class Codes: F24H 1/40 with water tube or tubes

Abstract

Air pollution from combustion of air/gas mixtures is reduced effectively and reliably at a porous burner providing flames with a downstream reaction zone where the ignition of the air/gas mixture initiates. The porous burner is loaded with the air/gas mixture sufficiently, such as at from 1000 to 2500 kWm^-2 or 2200 to 5500 Btu/sqin-hr, to locate the downstream reaction zone at a downstream surface of the porous burner, while the air/gas mixture is provided with sufficient excess air, such as more than a quarter of excess air, for the flames to burn blue. In a typical combustion of that air/gas mixture, less than 20 ppm of NO_x are produced. A related method loads the porous burner with the air/gas mixture at from 1000 to 2000 kWm^-2 or 2200 to 4400 Btu/sqin-hr, while providing that air/gas mixture with more than about forty-five percent of excess air for the flames to burn blue. That combustion of the air/gas mixture including its excess air produces less than 10 ppm of NO_x.

Claims

1. A method of operating a porous burner with an air/gas mixture, comprising in combination:

igniting said air/gas mixture at said porous burner to produce flames with a downstream reaction zone;

loading said porous burner with said air/gas mixture sufficiently by force-feeding to locate said downstream reaction zone at a downstream surface of said porous burner; and

providing said air/gas mixture with sufficient excess air for said flames to burn blue in a combustion of said air/gas mixture including said excess air producing less than 20 ppm of NO_x.

2. A method as in claim 1, wherein:

said air/gas mixture is provided with more than a quarter of excess air.

3. A method as in claim 1, including:

intimately admixing the gas and the air in said air/gas mixture by forcing said air/gas mixture including said excess air through a flow impedance ahead of said porous burner.

4. A method as in claim 3, wherein:

said air/gas mixture is provided with more than a quarter of excess air.

5. A method as in claim 1, including:

intimately admixing the gas and the air in said air/gas mixture by forcing said air/gas mixture including said excess air through a bent path ahead of said porous burner.

6. A method as in claim 5, wherein:

said air/gas mixture is provided with more than a quarter of excess air.

7. A method as in claim 1, wherein:

the gas and the air in said air/gas mixture are intimately admixed by feeding said air/gas mixture including said excess air through a blower and force-feeding air/gas mixture including said excess air to said porous burner with said blower.

8. A method as in claim 7, wherein:

said air/gas mixture is provided with more than a quarter of excess air.

9. A method of operating a porous burner with an air/gas mixture, comprising in combination:

igniting said air/gas mixture at said porous burner to produce flames with a downstream reaction zone;

loading said porous burner with said air/gas mixture at from 1000 to 2500 kWm^-2 or 2200 to 5500 Btu/sqin-hr;

by force-feeding and

providing said air/gas mixture with sufficient excess air for said flames to burn blue in a combustion of said air/gas mixture including said excess air producing less than 20 ppm of NO_x.

10. A method as in claim 9, wherein:

said air/gas mixture is provided with more than a quarter of excess air.

11. A method as in claim 9, including:

intimately admixing the gas and the air in said air/gas mixture by forcing said air/gas mixture including said excess air through a flow impedance ahead of said porous burner.

12. A method as in claim 11, wherein:

said air/gas mixture is provided with more than a quarter of excess air.

13. A method as in claim 9, including:

intimately admixing the gas and the air in said air/gas mixture by forcing said air/gas mixture including said excess air through a bent path ahead of said porous burner.

14. A method as in claim 13, wherein:

said air/gas mixture is provided with more than a quarter of excess air.

15. A method as in claim 9, wherein:

the gas and the air in said air/gas mixture are intimately admixed by feeding said air/gas mixture including said excess air through a blower and force-feeding air/gas mixture including said excess air to said porous burner with said blower.

16. A method as in claim 15, wherein:

said air/gas mixture is provided with more than a quarter of excess air.

17. A method of operating a porous burner with an air/gas mixture, comprising in combination:

igniting said air/gas mixture at said porous burner to produce flames with a downstream reaction zone;

loading said porous burner with said air/gas mixture at from 1000 to 2000 kWm^-2 or 2200 to 4400 Btu/sqin-hr;

by force-feeding and

providing said air/gas mixture with more than about forty-five percent of excess air for said flames to burn blue in a combustion of said air/gas mixture including said excess air producing less than 10 ppm of NO_x.

18. A method as in claim 17, including:

intimately admixing the gas and the air in said air/gas mixture by forcing said air/gas mixture including said excess air through a flow impedance ahead of said porous burner.

19. A method as in claim 17, including:

intimately admixing the gas and the air in said air/gas mixture by forcing said air/gas mixture including said excess air through a bent path ahead of said porous burner.

20. A method as in claim 17, wherein:

the gas and the air in said air/gas mixture are intimately admixed by feeding said air/gas mixture including said excess air through a blower and force-feeding air/gas mixture including said excess air to said porous burner with said blower.