Secondary fuel nozzle with readily customizable pilot fuel flow rate

• US 6,857,271 B2
• Filed: 12/16/2002
• Issued: 02/22/2005
• Est. Priority Date: 12/16/2002
• Status: Expired due to Term

• Current Assignee: Ansaldo Energia Switzerland AG (Ansaldo Energia SPA)
• Original Assignee: Power Systems Mfg. LLC (Hanwha Corporation)
• Inventors: Kraft, Robert J., Cires, Alfredo
• Primary Examiner(s): Kim, Ted
• Application Number:
  US10/320,990
• Publication Number:
  US 20040123597A1
• Time in Patent Office: 799 Days
• Field of Search: 607/37, 607/40, 607/46, 607/47, 607/48, 239399-406
• US Class Current: 60/737
• CPC Class Codes: F02C 7/32 Arrangement, mounting, or driving, of auxiliaries
• CPC Class Codes: F23D 14/64 with injectors
• CPC Class Codes: F23R 3/286 having fuel-air premixing devices F23R3/30 takes precedence

Abstract

An improved secondary fuel distribution system having a readily adjustable premix pilot nozzle for use in a gas turbine combustor is disclosed. The secondary fuel nozzle assembly has a premix fuel nozzle comprising an annular tubular manifold and a premix pilot nozzle. Multiple embodiments of premix pilot nozzles are disclosed that have a fuel flow rate that can be controlled and adjusted as required, including a plate and feed hole combination, a pressfit premix pilot nozzle, and a premix pilot nozzle that is threaded into the secondary fuel nozzle assembly.

Claims

1. A method of providing a secondary fuel distribution system having an annular premix nozzle and a separate premix pilot nozzle with a means to adjust and fine tune a fuel flow through said premix pilot nozzle, said method comprising the steps:

providing a housing for receiving fuel from a supply source and delivering fuel to a secondary fuel nozzle assembly which is attached to said housing, said secondary fuel nozzle assembly comprising;

an elongated tube having opposing first and second ends and having a centerline defined therethrough;

a nozzle tip region located proximate said elongated tube second end;

a premix fuel nozzle comprising an annular tubular manifold circumferentially disposed around said elongated tube by a set of support members which are fixed to an extend radially outwards from said elongated tube, said manifold in fluid communication with said support members and having a plurality of first holes situated about its periphery facing in a downstream direction for dispersing fuel to a combustor, such that said fuel mixes with air passing around said manifold, wherein at least one of said first holes is offset circumferentially from said support member;

a central core coaxial with said centerline and located radially within said elongated tube thereby forming a first passage between said central core and said elongated tube, said central core extending from proximate said elongated tube first opposing end to said second opposing end, said central core containing a second passage extending from proximate said elongated tube first opposing end to proximate said premix fuel nozzle for supplying fuel to said premix fuel nozzle, said central core also containing a third passage extending from downstream of said premix fuel nozzle to proximate said second opposing end each of said second and third passages are coaxial with said centerline, said central core further containing a plurality of air flow channels in fluid communication with said third passage and arranged in an annular array about said centerline, said air flow channels having an air flow inlet region and air flow exit region, and said first passage extending from proximate said first opposing end to upstream of said air flow inlet region of said air flow channels;

means for transferring fuel from said first passage to said nozzle tip region;

a premix pilot nozzle fixed to said central core at an axial position proximate said premix fuel nozzle such that said pilot nozzle is positioned within said third passage and coaxial with said centerline, said premix pilot nozzle having opposing first and second ends, an outer surface, and an internal passage, said pilot nozzle having a plurality of second holes proximate said pilot nozzle second end for dispersing fuel to said third passage, and a plate fixed to said first end of said premix pilot nozzle;

determining a desired fuel flow rate for said premix pilot nozzle; and

,

placing at least one feed hole in said plate such that said internal passage is in fluid communication with said second passage and said at least one feed hole can be sized to match said desired fuel flow rate.

2. The method of claim 1 wherein said plate is brazed to said premix pilot nozzle.

3. The method of claim 1 wherein said plate is welded to said premix pilot nozzle.

4. The method of claim 1 wherein said at least one feed hole has an effective flow area greater than the combined effective flow area of said second holes in said premix pilot nozzle.

5. The method of claim 1 wherein said premix pilot nozzle is of circular cross section and said internal passage has a passage diameter.

6. The method of claim 1 wherein said at least one feed hole of said plate restricts the flow of fuel to said premix pilot nozzle such that the pressure of fuel in said second passage is higher than the fuel pressure in said internal passage of said premix pilot fuel nozzle.

7. The method of claim 1 wherein said secondary fuel nozzle assembly further comprises a swirler positioned proximate said nozzle tip region of said third passage.

8. The method of claim 1 wherein said means for transferring fuel from said first passage to said nozzle tip region comprises a plurality of tubes arranged in an annular array about said centerline, radially between said central core and said elongated tube, and extending from said first passage to said nozzle tip region.