Title of Invention

A FUEL INJECTOR FOR A GAS TURBINE ENGINE

Abstract A fuel injector comprising: a fuel supply conduit (1) for conveying fuel from a base end (3) of the fuel injector to a tip end (5) of the injector; a nozzle (7) at the tip end (5) of the injector for injecting the fuel into a combustion chamber; thermal conductor means (11,12) for conducting heat from said nozzle (7) at the tip end of the injector to the base end of the injector to cool the nozzle; and a housing (13) for said fuel supply conduit (1), said nozzle (7) and said thermal conductor means, wherein said thermal conductor means is thermally insulated from said fuel supply conduit (1) between said tip (5) and base (3) ends of the injector.
Full Text WO 2006/087367 1 PCT/EP2006/060050
Description:
A fuel injector
This invention relates to a fuel injector.
More particularly, the invention relates to a fuel injector
comprising: a fuel supply conduit for conveying fuel from a
base end of the fuel injector to a tip end of the injector; a
nozzle at the tip end of the injector for injecting the fuel
into a combustion chamber; and a housing for the fuel supply
conduit and the nozzle.
It is important to carefully manage the temperature of
the nozzle at the tip end of the injector so as to avoid the
formation of carbon deposits on the internal surfaces of the
nozzle and the fuel supply conduit to the nozzle. Such carbon
deposits potentially arise due to chemical cracking of the
liquid fuel at temperatures exceeding known values. For
example, diesels and kerosenes typically chemically crack at
temperatures exceeding about 200°C.
It is known to tolerate the formation of a certain
amount of carbon provided the flow rate of the liquid fuel
through the fuel supply conduit and nozzle is sufficiently
high to prevent most of this carbon from adhering to the
internal surfaces of these components. This approach has been
used in fuel injectors for gas turbine engines, where there
is careful control of the near wall Reynolds numbers in the
regions of the fuel supply conduit and nozzle at greatest
risk. Thus, in such fuel injectors the temperature of the
nozzle may exceed 200°C. However, a problem arises where the
gas turbine engine is required to operate over a wide range
of loads such that the liquid fuel flow rate may reduce but
the nozzle temperature remain around or above 200°C. This
occurs for example in gas turbine engines employing so called
staged systems such as those used on Dry Low Emissions (DLE)
combustors.
According to the present invention there is provided a
fuel injector comprising: a fuel supply conduit for conveying
fuel from a base end of the fuel injector to a tip end of the
injector; a nozzle at the tip end of the injector for

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injecting the fuel into a combustion chamber; thermal
conductor means for conducting heat from said nozzle at the
tip end of the injector to the base end of the injector to
cool the nozzle; and a housing for said fuel supply conduit,
said nozzle and said thermal conductor means.
In a first fuel injector according to the present
invention said housing extends the full length of said fuel
supply conduit.
In a second fuel injector according to the present
invention said housing does not extend along a mid-portion of
the length of said fuel supply conduit such that over this
mid-portion the fuel supply conduit and said thermal
conductor means are exposed to the exterior of said fuel
injector.
Preferably, said thermal conductor means is in physical
contact with said nozzle, but is thermally insulated from
both said fuel supply conduit and said housing between said
tip and base ends of the injector. The thermal insulation
suitably comprises a physical spacing between said thermal
conductor means and both said fuel supply conduit and said
housing between said tip and base ends of the injector.
Preferably, there is minimal physical contact between
said thermal conductor means and said housing at the tip end
of the injector.
Preferably, said thermal conductor means is recessed
from the end face of said tip end of the injector, and said
housing is formed so as to extend between said thermal
conductor means and said end face of said tip end of the
injector.
Preferably, said thermal conductor means is in physical
contact with said housing at the base end of the injector.
Preferably, cooling is applied to said base end of the
injector. The cooling is suitably achieved by utilising
assist gas used by the injector to assist in the injection of
fuel into the combustion chamber.
Preferably, said thermal conductor means is in the form
of a tube which extends between said tip and base ends of the

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injector, and surrounds and is co-axial with said fuel supply
conduit.
The invention will now be described, by way of example,
with reference to the accompanying schematic drawings, in
which Figs 1 to 4 are respectively longitudinal cross-
sections through first to fourth fuel injectors in accordance
with the present invention.
Referring to Fig 1, the first fuel injector comprises: a
fuel supply conduit 1 for conveying fuel from a base end 3 of
the fuel injector to a tip end 5 of the injector; a nozzle 7
at tip end 5 for injecting the fuel into a combustion
chamber, see fuel spray 9; a tube 11 of high thermal
conductance for conducting heat from nozzle 7 at tip end 5 to
base end 3 to cool nozzle 7; and a housing 13 for fuel supply
conduit 1, nozzle 7 and tube 11.
At tip end 5 tube 11 is in physical contact with nozzle
7 such as to achieve good thermal communication with nozzle
7. Similarly, at base end 3 tube 11 is in physical contact
with housing 13 such as to achieve good thermal communication
with housing 13. This physical contact is achieved by means
of flange 12 of tube 11. Between tip end 5 and base end 3,
tube 11 is physically spaced from both fuel supply conduit 1
and housing 13 so as to be thermally insulated from these
components between the tip and base ends. At tip end 5 tube
11 is centred within housing 13 by location means 14. The
form of location means 14 must be such that there is minimal
physical contact between tube 11 and housing 13 so as to
ensure minimal thermal communication between these
components. Accordingly, location means 14 suitably comprises
posts having tapered ends or a ring having a knife edge. At
base end 3 fuel supply conduit 1 communicates with fuel
supply end fitting 16.
The end 15 of tube 11 at tip end 5 of the injector is
recessed from the end face 17 of tip end 5 so as to distance
tube 11 from the heat at end face 17. Further, housing 13
includes shroud formation 19 which extends between end 15 of
tube 11 and end face 17 to screen tube 11 from the heat at
end face 17.

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In use of the fuel injector, a temperature gradient is
present along tube 11 between hot tip end 5 and much cooler
base end 3. Consequently, heat within nozzle 7 is conducted
along tube 11 to base end 3 to cool nozzle 7 and fuel supply
conduit 1. The minimal physical contact between tube 11 and
housing 13 ensures that heat take-up by tube 11 is almost
exclusively from nozzle 7, i.e. ensures that tube 11 operates
to cool nozzle 7 only and not housing 13. The spacing between
tube 11 and both fuel supply conduit 1 and housing 13 ensures
that the temperature gradient along tube 11 is not upset by
thermal communication with either of these components. The
recessing of end 15 of tube 11, and the screening of end 15
by shroud formation 19, ensures minimal take-up by tube 11 of
the heat at end face 17 of tip end 5, thereby maximising heat
take-up from nozzle 7.
Tube 11 is suitably made from aluminium, copper or
magnesium. In the case of copper it is appropriate to coat
the tube, eg with chrome, to protect against interaction with
nickel that may be present in the fuel injector/engine. Tube
11 may also be made from tungsten or graphite. In the case of
graphite the tube would be constructed from discrete pieces
of graphite, eg bars of graphite, assembled within an
appropriate support structure, eg of aluminium or other
metal, due to the low strength of graphite. Each of the
discrete pieces of graphite would be appropriately
directionally oriented to provide the high thermal
conductance.
It is to be realised that there are principally two
paths by which heat present in nozzle 7 may be conducted away
from nozzle 7. These paths are high conductance tube 11 and
fuel supply conduit 1. It is of course desired to minimise
the heat taken by fuel supply conduit 1 so as to
minimise/prevent chemical cracking of the fuel within conduit
1. The design of the fuel injector should be such that at the
very least 60% of the heat flux is taken by tube 11 with the
remaining 40% taken by fuel supply conduit 1. It is
preferable that at least 80% of the heat flux is taken by
tube 11 with the remaining 20% taken by conduit 1. It is more

WO 2006/087367 5 PCT/EP2006/060050
preferable that at least 90% of the heat flux is taken by
tube 11 with the remaining 10% taken by conduit 1.
Additional cooling of base end 3 may be used to make
steeper the temperature gradient along tube 11 and hence
improve the efficiency of cooling of nozzle 7 and fuel supply
conduit 1. An example of such additional cooling is present
in the second fuel injector of Fig 2.
In the second fuel injector of Fig 2 like parts to those
of the first fuel injector of Fig 1 are labelled with the
same reference numerals. The second fuel injector differs
from the first in that air is used to assist the formation of
fuel spray 9, and also to help cool base end 3 of the fuel
injector. Thus, air enters via port 31, circulates around air
assist gallery 33 to help cool base end 3, travels between
flange 12 and fitting 16, travels along the space between
fuel supply conduit 1 and tube 11, and enters nozzle 7 where
it assists in known manner the formation of fuel spray 9.
In the third fuel injector of Fig 3 like parts to those
of the first fuel injector of Fig 1 are labelled with the
same reference numerals. The third fuel injector differs from
the first in that housing 13 does not extend along a mid-
portion of the length of fuel supply conduit 1 and tube 11
such that over this mid-portion conduit 1 and tube 11 are
exposed to the exterior of the fuel injector. In other words,
at region 41 conduit 1 and tube 11 leave housing 13 so as to
be exposed to the exterior of the fuel injector, to return to
housing 13 at region 43.
In the fourth fuel injector of Fig 4 like parts to those
of the second fuel injector of Fig 2 are labelled with the
same reference numerals. The fourth fuel injector differs
from the second in that housing 13 does not extend along a
mid-portion of the length of fuel supply conduit 1 and tube
11 such that over this mid-portion conduit 1 and tube 11 are
exposed to the exterior of the fuel injector. In other words,
at region 51 conduit 1 and tube 11 leave housing 13 so as to
be exposed to the exterior of the fuel injector, to return to
housing 13 at region 53.

WO 2006/087367 6 PCT/EP2006/060050
It is to be appreciated that a fuel injector according
to the present invention when utilised in a gas turbine
engine increases the load range over which the engine may
operate without risk of problem due to carbon deposits. It
does this by very efficiently cooling the nozzle of the fuel
injector. This enables the flow rate of fuel within the
injector to drop without risk that the flow is then
insufficient to prevent the adherence of carbon deposits on
the internals of the injector.

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PCT/EP2006/060050
Patent Claims:
1. A fuel injector comprising: a fuel supply conduit (1)
for conveying fuel from a base end (3) of the fuel injector
to a tip end (5) of the injector; a nozzle (7) at the tip end
(5) of the injector for injecting the fuel into a combustion
chamber; thermal conductor means (11) for conducting heat
from said nozzle (7) at the tip end (5) of the injector to
the base end (3) of the injector to cool the nozzle (7) and
recessed from an end face (17) of said tip end (5) of the
injector; and a housing (13) for said fuel supply conduit
(1), said nozzle (7) and said thermal conductor means (11),
wherein said thermal conductor means (11) is thermally
insulated from said fuel supply conduit (1) between said tip
and base ends (5,3) of the injector and said housing (13) is
formed so as to extend between said thermal conductor means
(11) and said end face (17) of said tip end (5) of the
injector and to screen an end (15) of thermal conductor means
(11) by shroud formation (19).
2. An injector according to claim 1 wherein said housing
extends the full length of said fuel supply conduit.
3. An injector according to claim 1 wherein said housing
does not extend along a mid-portion of the length of said
fuel supply conduit such that over this mid-portion the fuel
supply conduit and said thermal conductor means are exposed
to the exterior of said fuel injector.
4. An injector according to claim 1 or claim 2 or claim 3
wherein said thermal conductor means is in physical contact
with said nozzle, and is thermally insulated from said
housing between said tip and base ends of the injector.
5. An injector according to claim 4 wherein said thermal
insulation comprises a physical spacing between said thermal
conductor means and both said fuel supply conduit and said
housing between said tip and base ends of the injector.

2005P00543WO
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PCT/EP2006/060050
6. An injector according to any one of the preceding claims
wherein there is minimal physical contact between said
thermal conductor means and said housing at the tip end of
the injector.
7. An injector according to any one of the preceding claims
wherein said thermal conductor means is in physical contact
with said housing at the base end of the injector.
8. An injector according to any one of the preceding claims
wherein cooling is applied to said base end of the injector.
9. An injector according to claim 8 wherein said cooling is
achieved by utilising assist gas used by the injector to
assist in the injection of fuel into the combustion chamber.
10. An injector according to any one of the preceding claims
wherein said thermal conductor means is in the form of a tube
which extends between said tip and base ends of the injector,
and surrounds and is co-axial with said fuel supply conduit.
11. An injector according to any one of the preceding claims
wherein said thermal conductor means comprises a material
selected from the group consisting of aluminium, copper,
magnesium, tungsten and graphite.
12. An injector according to any one of the preceding claims
wherein said thermal conductor means is designed such that it
takes at least 60% of the heat flux from said nozzle.
13. An injector according to any one of the preceding claims
wherein said thermal conductor means is designed such that it
takes at least 80% of the heat flux from said nozzle.
14. An injector according to any one of the preceding claims
wherein said thermal conductor means is designed such that is
takes at least 90% of the heat flux from said nozzle.

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PCT/EP2006/060050
15. An injector according to any one of the preceding claims
suitable for use in a gas turbine engine.

A fuel injector comprising: a fuel supply conduit (1) for conveying fuel from a base end (3) of the fuel injector to
a tip end (5) of the injector; a nozzle (7) at the tip end (5) of the injector for injecting the fuel into a combustion chamber; thermal
conductor means (11,12) for conducting heat from said nozzle (7) at the tip end of the injector to the base end of the injector to
cool the nozzle; and a housing (13) for said fuel supply conduit (1), said nozzle (7) and said thermal conductor means, wherein
said thermal conductor means is thermally insulated from said fuel supply conduit (1) between said tip (5) and base (3) ends of the
injector.

Documents:

02806-kolnp-2007-abstract.pdf

02806-kolnp-2007-claims.pdf

02806-kolnp-2007-correspondence others 1.1.pdf

02806-kolnp-2007-correspondence others 1.2.pdf

02806-kolnp-2007-correspondence others.pdf

02806-kolnp-2007-description complete.pdf

02806-kolnp-2007-drawings.pdf

02806-kolnp-2007-form 1.pdf

02806-kolnp-2007-form 18.pdf

02806-kolnp-2007-form 2.pdf

02806-kolnp-2007-form 3.pdf

02806-kolnp-2007-form 5.pdf

02806-kolnp-2007-gpa.pdf

02806-kolnp-2007-international publication.pdf

02806-kolnp-2007-international search report.pdf

02806-kolnp-2007-pct request form.pdf

2806-KOLNP-2007-ABSTRACT.pdf

2806-KOLNP-2007-AMANDED CLAIMS.pdf

2806-KOLNP-2007-DESCRIPTION (COMPLETE).pdf

2806-KOLNP-2007-DRAWINGS.pdf

2806-KOLNP-2007-EXAMINATION REPORT REPLY RECIEVED.pdf

2806-KOLNP-2007-FORM 1.pdf

2806-KOLNP-2007-FORM 2.pdf

2806-KOLNP-2007-FORM 3.pdf

2806-KOLNP-2007-FORM-27.pdf

2806-KOLNP-2007-OTHERS.pdf

2806-KOLNP-2007-PETITION UNDER RULE 137.pdf

abstract-02806-kolnp-2007.jpg


Patent Number 247690
Indian Patent Application Number 2806/KOLNP/2007
PG Journal Number 18/2011
Publication Date 06-May-2011
Grant Date 02-May-2011
Date of Filing 01-Aug-2007
Name of Patentee SIEMENS AKTIENGESELLSCHAFT
Applicant Address WITTELSBACHERPLATZ 2, 80333 MUNCHEN
Inventors:
# Inventor's Name Inventor's Address
1 SENIOR, PETER 8, MARSTON CRESENT, COUNTERSTHORPE LEICESTERSHIRE LE8 5PY
2 GOODWIN, PETER, JARVIS 1, WELLINGTON CLOSE, SKELLINGTHORPE LINCOLNSHIRE LN6 5UH
3 WILBRAHAM, NIGEL 44, COLDSTREAM DRIVE, WORDSLEY, STOURBRIDGE WEST MIDLANDS DY8 5QZ
PCT International Classification Number F02M 51/06
PCT International Application Number PCT/EP2006/060050
PCT International Filing date 2006-02-17
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 0503497.0 2005-02-19 U.K.