Burner with a series of fuel gas ejectors and a perforated flame holder

Patent metadata

Field	Value
Publication number	US-9562682-B2
Application number	US-201514741098-A
Country	US
Kind code	B2
Filing date	Jun 16, 2015
Priority date	Feb 14, 2013
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

A combustion system outputs fuel gas from a plurality of fuel ejectors toward a forward end of a burner wall and preheats a perforated flame holder by sustaining combustion reaction of the fuel gas at combustion zone between the burner wall and a perforated flame holder. The combustion system then outputs fuel gas from the fuel ejectors onto the perforated flame holder and sustains a combustion reaction of the fuel gas within the perforated flame holder.

First claim

What is claimed is:

1. A burner providing reduced NO x emissions comprising:
a burner wall having a forward end;
at least one first fuel gas nozzle positioned longitudinally rearward of and laterally outward from the forward end of the burner wall;
at least one fuel gas delivery port positioned in the first fuel gas nozzle to deliver fuel gas in a flow path outside of the burner wall to a combustion zone at the forward end of the burner wall;
at least one exterior ledge provided on the burner wall and positioned between the fuel gas delivery port and the forward end of the burner wall such that at least a portion of the fuel gas traveling in the flow path will contact the exterior ledge, the exterior ledge being spaced apart from the forward end; and
a perforated flame holder including:
an input face proximal to the front end of the burner wall;
an output face distal from the burner; and
a plurality of perforations extending between the input and output faces;

wherein the burner wall and the at least one first fuel gas nozzle are configured to preheat the perforated flame holder to a threshold temperature by supporting a first combustion reaction in the combustion zone; and further comprising
at least one second fuel gas nozzle configured to output fuel gas onto the perforated flame holder after the perforated flame holder has been heated to the threshold temperature; and further comprising
a control circuit operatively coupled to the at least one first fuel gas nozzle and the at least one second fuel gas nozzle;
wherein the control circuit is configured to:
cause the at least one first fuel gas nozzle to output fuel gas toward the forward end of the burner wall during a preheating phase;
terminate the preheating phase after the perforated flame holder has reached a threshold temperature; and
cause the at least one second fuel gas nozzle to output fuel gas onto the perforated flame holder after the preheating phase has been terminated.

2. The burner of claim 1 , wherein the exterior ledge is positioned longitudinally rearward of and laterally outward from the forward end of the burner wall.

3. The burner of claim 1 , wherein the combustion zone is positioned between the forward end of the burner wall and the perforated flame holder.

4. The burner of claim 1 , wherein the at least one first fuel gas nozzle is configured to output fuel gas onto the perforated flame holder after the perforated flame holder has been heated to the threshold temperature, the perforated flame holder being configured to support a combustion reaction of the fuel gas within the apertures.

5. The burner of claim 1 , comprising a motor coupled to the at least first one fuel gas nozzle and configured to reposition the at least one fuel gas nozzle to output fuel gas onto the perforated flame holder after the perforated flame holder has been heated to the threshold temperature.

6. The burner of claim 1 , comprising:
an opening in the burner wall at the forward end; and
a central channel in the burner wall configured to output an oxidant toward the perforated flame holder.

7. A burner providing reduced NOx emissions for use in a heating system having a flue gas therein, the burner comprising:
a burner wall having a forward end;
a series of first fuel gas ejectors, each having only a single fuel gas ejection port provided therein, the first fuel gas ejectors and the single fuel gas ejection ports provided therein being positioned and the fuel gas ejection ports being configured to deliver fuel gas from the first fuel gas ejectors in a plurality of adjacent free jet flow streams outside of the burner wall toward a combustion zone at the forward end of the burner wall, each of the adjacent free jet flow streams being effective for entraining a portion of the flue gas in the fuel gas and the fuel gas ejection ports being positioned longitudinally rearward and laterally outward with respect to the forward end of the burner wall;
an impact structure positioned between the fuel gas ejection ports and the forward end of the burner wall such that the impact structure will be contacted by at least a portion of the fuel gas traveling in the flow streams; and
a perforated flame holder including:
an input face proximal to the front end of the burner wall;
an output face distal from the burner; and
a plurality of perforations extending between the input and output faces;

wherein the burner wall and the first fuel gas ejectors are configured to preheat the perforated flame holder to a threshold temperature by supporting a first combustion reaction in the combustion zone; and further comprising
at least one second fuel gas ejector configured to output fuel gas onto the perforated flame holder after the perforated flame holder has been heated to the threshold temperature; and
a control circuit operatively coupled to the first fuel gas ejectors and the at least one second fuel gas ejector;
wherein the control circuit is configured to:
cause the first fuel gas ejectors to output fuel gas toward the forward end of the burner wall during a preheating phase;
terminate the preheating phase after the perforated flame holder has reached a threshold temperature; and
cause the at least one second fuel gas ejector to output fuel gas onto the perforated flame holder after the preheating phase has been terminated.

8. The burner of claim 7 , wherein the impact structure is an exterior ledge provided on the burner wall.

9. The burner of claim 8 , wherein the exterior ledge is spaced longitudinally rearward of and laterally outward from the forward end of the burner wall.

10. The burner of claim 9 , wherein:
the burner wall has a longitudinal axis; and
the fuel gas ejection ports are oriented such that the flow streams leave the fuel gas ejection ports at an angle from the longitudinal axis in the range of from about 13° to about 26°.

11. The burner of claim 7 , comprising a plurality of the at least one second fuel gas ejector positioned to eject fuel gas onto the perforated flame holder.

12. The burner of claim 11 , wherein the second fuel gas ejectors are configured to eject fuel onto the perforated flame holder after the perforated flame holder has been heated to threshold temperature.

13. The burner of claim 12 , wherein the first fuel gas ejectors are configured to stop ejecting fuel gas after the perforated flame holder has reached the threshold temperature.

14. The burner of claim 13 , wherein the control circuit is configured to control the ejection of fuel from the first and second fuel gas ejectors.

15. The burner of claim 7 , comprising a motor coupled to the first fuel gas ejectors and the control circuit, the motor being configured to reposition the first fuel gas ejectors to output fuel gas onto the perforated flame holder after the perforated flame holder has been preheated to the threshold temperature.

16. The burner of claim 15 , wherein the motor repositions the first fuel gas ejectors by moving the first fuel gas ejectors closer to the perforated flame holder.

17. The burner of claim 15 , wherein the motor repositions the first fuel gas ejectors by adjusting a position of the respective fuel gas ejection ports.

18. A method comprising:
preheating a perforated flame holder to a threshold temperature by:
ejecting fuel gas outside of a burner wall of the burner in free jet flow such that at least a portion of flue gas is entrained in said fuel gas and said fuel gas travels outside of said burner wall to a combustion zone having a beginning end substantially a

Assignees

• Clearsign Comb Corp

Inventors

• Karkow Douglas W
• Breidenthal Robert
• Colannino Joseph
• Wiklof Christopher A

Classifications

• F23N2221/00

  Pretreatment or prehandling · CPC title

• F23N2227/22

  Pilot burners · CPC title

• F23C2900/00

  Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor · CPC title

• F23D2203/1012

  tubular · CPC title

• F27D11/06

  Induction heating, i.e. in which the material being heated, or its container or elements embodied therein, form the secondary of a transformer · CPC title