Burner for operating a heat generator

• US 5,954,495 A
• Filed: 10/09/1998
• Issued: 09/21/1999
• Est. Priority Date: 10/14/1997
• Status: Expired due to Fees

• Current Assignee: Alstom SA
• Original Assignee: ABB Research Ltd. (ABB Limited)
• Inventors: Ruck, Thomas, Knopfel, Hans Peter
• Primary Examiner(s): DORITY, CARROLL B
• Application Number:
  US09/169,140
• Time in Patent Office: 347 Days
• Field of Search: 431/285, 431/284
• US Class Current: 431/285
• CPC Class Codes: F23C 2900/07002 Premix burners with air inlet slots obtained between offset curved wall surfaces, e.g. double cone burners
• CPC Class Codes: F23C 7/002 the air being submitted to a rotary or spinning motion cyclonic combustion chamber F23C3/006
• CPC Class Codes: F23D 11/402 Mixing chambers downstream of the nozzle
• 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 14/78 Cooling burner parts
• CPC Class Codes: F23D 17/002 gaseous or liquid fuel
• CPC Class Codes: F23D 23/00 Assemblies of two or more burners gas burners with provision for a retention flame F23D14/26
• CPC Class Codes: F23D 2900/14021 Premixing burners with swirling or vortices creating means for fuel or air

Abstract

In a burner for operating a combustion chamber, which burner essentially comprises a swirl generator (100), a transition piece (200) arranged downstream of the swirl generator, and a mixing tube (20), transition piece (200) and mixing tube (20) forming the mixing section of the burner and being arranged upstream of a combustion space (30), a pilot-burner system (300) is arranged in the lower region of the mixing tube (20), which pilot-burner system (300), at minimized pollutant emissions, stabilizes the flame front, in particular in the transient load ranges.

Claims

1. A burner for operating a heat generator, the burner comprising a swirl generator for a combustion-air flow and means for injecting at least one fuel into the combustion-air flow, a mixing section being arranged downstream of the swirl generator and having, inside a first part of the section in the direction of flow, a number of transition passages for passing a flow formed in the swirl generator into a mixing tube arranged downstream of these transition passages, wherein a pilot-burner system (300) is arranged about the lower region of the mixing tube (20) in such a way as to act in a combustion chamber (30) arranged downstream of the mixing tube (20), which pilot-burner system (300) comprises at least two media-carrying chambers (301, 302) and a further common chamber (308) arranged downstream, wherein the media (303, 304) from the other two chambers (301, 302) can be mixed in this chamber (308) arranged downstream, and wherein the chamber (308) arranged downstream has means for forming pilot burners (306) which act in the combustion space (30) and can be operated by the mixture of the two media (303, 304).

2. The burner as claimed in claim 1, wherein the media-carrying chambers (301, 303) are of annular and juxtaposed design, wherein a gaseous fuel (303) flows through the first annular chamber (301) and an air quantity (304) flows through the second annular chamber (302), and wherein fitted in the second annular chamber (302) are means (305) which enable the air (304) flowing there to bring about impingement cooling on a heat-shield plate (307) arranged at the end of the pilot-burner system (300).

3. The burner as claimed in claim 2 wherein the means for forming the impingement cooling is a perforated plate (305) forming a base in the juxtaposed annular chamber (302).

4. The burner as claimed in claim 1, wherein the means for injecting comprise a ring (190) arranged on the head side of the swirl generator (100) and in interaction with a fuel nozzle (103), wherein this ring (190) has a number of bores (161) arranged in the peripheral direction, and wherein a fuel (170) can be injected into an air quantity (160) flowing through the bores (161).

5. The burner as claimed in claim 4, wherein the bores (161) are directed so as to slant forward.

6. The burner as claimed in claim 4, wherein the fuel nozzle (103) is surrounded by an annular air chamber (180).

7. The burner as claimed in claim 1, wherein the burner front of the mixing tube (20) toward the combustion space (30) arranged downstream is formed with a breakaway edge (A).

8. The burner as claimed in claim 1, wherein the number of transition passages (201) in the mixing section (220) corresponds to the number of partial flows formed by the swirl generator (100).

9. The burner as claimed in claim 1, wherein the mixing tube (20) arranged downstream of the transition passages (201) is provided with openings (21) in the direction of flow and in the peripheral direction for injecting an air flow into the interior of the mixing tube (20).

10. The burner as claimed in claim 9, wherein the openings (21) run at an acute angle relative to the burner axis (60) of the mixing tube (20).

11. The burner as claimed in claim 1, wherein the cross section of flow of the mixing tube (20) downstream of the transition passages (201) is less than, equal to or greater than the cross section of the flow (40) formed in the swirl generator (100, 100a).

12. The burner as claimed in claim 1, wherein the combustion chamber (30) is arranged downstream of the mixing section (220), wherein there is a jump in cross section between the mixing section (220) and the combustion chamber (30), which jump in cross section induces the initial cross section of flow of the combustion chamber (30), and wherein a backflow zone (50) can take effect in the region of this jump in cross section.

13. The burner as claimed in claim 1, wherein there is a diffuser and/or a Venturi section upstream of the burner front (70).

14. The burner as claimed in claim 1, wherein the swirl generator (100) consists of at least two hollow, conical sectional bodies (101, 102;

130, 131, 132, 133;

140, 141, 142,

     143) which are nested one inside the other in the direction of flow, wherein the respective longitudinal symmetry axes (101b, 102b;

130a, 131a, 132a, 133a;

140a, 141a, 142a, 143a) of these sectional bodies run mutually offset in such a way that the adjacent walls of the sectional bodies form ducts (119,

     120), tangential in their longitudinal extent, for a combustion-air flow (115), and wherein at least one fuel nozzle (103) can take effect in the interior space (114) formed by the sectional bodies.

15. The burner as claimed in claim 14, wherein further fuel nozzles (117) are arranged in the region of the tangential ducts (119, 120) in their longitudinal extent.

16. The burner as claimed in claim 14, wherein the sectional bodies (140, 141, 142, 143) have a blade-shaped profile in cross section.

17. The burner as claimed in claim 14, wherein the sectional bodies have a fixed cone angle, increasing conicity, or decreasing conicity in the direction of flow.

18. The burner as claimed in claim 14, wherein the sectional bodies are nested spirally one inside the other.