U.S. patent application number 12/422536 was filed with the patent office on 2010-10-14 for combined convection/effusion cooled one-piece can combustor.
This patent application is currently assigned to General Electric Company. Invention is credited to Ronald James Chila, Kevin Weston McMahan.
Application Number | 20100257863 12/422536 |
Document ID | / |
Family ID | 42335150 |
Filed Date | 2010-10-14 |
United States Patent
Application |
20100257863 |
Kind Code |
A1 |
Chila; Ronald James ; et
al. |
October 14, 2010 |
COMBINED CONVECTION/EFFUSION COOLED ONE-PIECE CAN COMBUSTOR
Abstract
An industrial turbine engine comprises a combustion section, an
air discharge section downstream of the combustion section, a
transition region between the combustion and air discharge section,
a combustion transition piece and a sleeve. The transition piece
defines an interior space for combusted gas flow. The sleeve
surrounds the combustor transition piece so as to form a flow
annulus between the sleeve and the transition piece. The sleeve
includes a first set of apertures for directing cooling air from
compressor discharge air into the flow annulus. The transition
piece includes an outer surface bounding the flow annulus and an
inner surface bounding the interior surface, and includes a second
set of apertures for directing cooling air in the flow annulus to
the interior space. Each of the second set of apertures extends
from an entry portion on the outer surface to an exit portion on
the inner surface.
Inventors: |
Chila; Ronald James; (Greer,
SC) ; McMahan; Kevin Weston; (Greer, SC) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH STREET, SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
42335150 |
Appl. No.: |
12/422536 |
Filed: |
April 13, 2009 |
Current U.S.
Class: |
60/755 |
Current CPC
Class: |
F23R 2900/03041
20130101; F23R 3/005 20130101; F23R 3/06 20130101 |
Class at
Publication: |
60/755 |
International
Class: |
F23R 3/00 20060101
F23R003/00 |
Claims
1. A turbine engine comprising: a combustion section; an air
discharge section downstream of the combustion section; a
transition region between the combustion section and air discharge
section; a combustor transition piece defining the combustion
section and transition region, said transition piece adapted to
carry combusted gas flow to a first stage of the turbine engine
corresponding to the air discharge section, the transition piece
defining an interior space for combusted gas flow; and a sleeve
surrounding the combustor transition piece so as to form a flow
annulus between the sleeve and the transition piece, said sleeve
including a first set of apertures for directing cooling air from
compressor discharge air into the flow annulus, wherein the
transition piece includes an outer surface bounding the flow
annulus and an inner surface bounding the interior space, the
transition piece includes a second set of apertures for directing
cooling air in the flow annulus to the interior space, and each of
the second set of apertures extends from an entry portion on the
outer surface to an exit portion on the inner surface.
2. The turbine engine of claim 1, wherein the first set of
apertures are normal to the sleeve.
3. The turbine engine of claim 1, wherein the first set of
apertures has a constant diameter ranging from 0.1 inch to 1.0
inch.
4. The turbine engine of claim 1, wherein one of the entry portion
and the exit portion is located further downstream than the other
of the entry portion and the exit portion.
5. The turbine engine of claim 4, wherein the combustor transition
piece is a can-annular, reverse-flow type such that combusted gas
flow and compressor discharge air flow are configured to be in
opposing directions such that longitudinal axes through the second
set of apertures form an acute angle with a direction of combusted
gas flow and an obtuse angle with a direction of compressor
discharge air flow.
6. The turbine engine of claim 1, wherein longitudinal axes through
the second set of apertures are oriented to form an acute angle
with a downstream tangent to the outer surface.
7. The turbine engine of claim 6, wherein the acute angle ranges
from 20.degree. to 35.degree..
8. The turbine engine of claim 1, wherein the second set of
apertures have a constant diameter from the entry portion to the
exit portion ranging from 0.02 inch to 0.04 inch.
9. The turbine engine of claim 1, wherein the second set of
apertures are substantially normal to the outer surface.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to means of cooling
components of a gas turbine, and more particularly, to the cooling
of a one-piece can combustor by a combination of convection cooling
and effusion cooling.
[0003] 2. Description of the Related Art
[0004] A gas turbine can operate with great efficiency if the
turbine inlet temperature can be raised to a maximum. However, the
combustion chamber, from which combusted gas originates before
entering the turbine inlet, reaches operating temperatures well
over 1500.degree. F. and even most advanced alloys cannot withstand
such temperatures for extended periods of use. Thus, the
performance and longevity of a turbine is highly dependent on the
degree of cooling that can be provided to the turbine components
which are exposed to extreme heating conditions.
[0005] The general concept of using compressor discharge air to
cool turbine components is known in the art. However, developments
and variations in turbine designs are not necessarily accompanied
by specific structures that are implemented with cooling mechanisms
for the turbine components. Thus, there is a need to embody cooling
mechanisms into newly developed turbine designs.
BRIEF DESCRIPTION OF THE INVENTION
[0006] Accordingly, it is an aspect of the present invention to
enhance conventional gas turbines.
[0007] To achieve the foregoing and other aspects and in accordance
with the present invention, an industrial turbine engine is
provided that comprises a combustion section, an air discharge
section downstream of the combustion section, a transition region
between the combustion and air discharge section, a combustor
transition piece defining the combustion section and transition
region, and a sleeve. Said transition piece is adapted to carry
combusted gas flow to a first stage of the turbine corresponding to
the air discharge section. The transition piece defines an interior
space for combusted gas flow. The sleeve surrounds the combustor
transition piece so as to form a flow annulus between the sleeve
and the transition piece. Said sleeve includes a first set of
apertures for directing cooling air from compressor discharge air
into the flow annulus. The transition piece includes an outer
surface bounding the flow annulus and an inner surface bounding the
interior surface. The transition piece includes a second set of
apertures for directing cooling air in the flow annulus to the
interior space. Each of the second set of apertures extends from an
entry portion on the outer surface to an exit portion on the inner
surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The foregoing and other aspects of the present invention
will become apparent to those skilled in the art to which the
present invention relates upon reading the following description
with reference to the accompanying drawings, in which:
[0009] FIG. 1 shows an example embodiment of a one-piece can
combustor in which the present invention can be implemented.
[0010] FIG. 2 shows a close-up, perspective view of a sleeve with
cooling air entry holes surrounding a transition piece with
effusion holes.
[0011] FIG. 3 shows a cross-sectional view across the cooling air
entry holes of the sleeve and effusion holes of the transition
piece.
DETAILED DESCRIPTION OF THE INVENTION
[0012] Example embodiments that incorporate one or more aspects of
the present invention are described and illustrated in the
drawings. These illustrated examples are not intended to be a
limitation on the present invention. For example, one or more
aspects of the present invention can be utilized in other
embodiments and even other types of devices.
[0013] FIG. 1 shows an embodiment of a single piece combustor 10 in
which the present invention can be implemented. This example
embodiment is a can-annular reverse-flow combustor 10 although the
invention is applicable to other types of combustors. The combustor
10 generates gases needed to drive the rotary motion of a turbine
by combusting air and fuel within a confined space and discharging
the resulting combustion gases through a stationary row of vanes.
In operation, discharge air from a compressor reverses direction as
it passes over the outside of the combustors 10 and again enters
the combustor 10 en route to the turbine. Compressed air and fuel
are burned in the combustion chamber. The combustion gases flow at
high velocity into a turbine section via a transition piece 120. As
discharge air flows over the outside surface of the transition
piece 120, it provides convective cooling to the combustor
components.
[0014] In FIG. 1, a transition piece 120 transitions directly from
a circular combustor head-end 100 to a turbine annulus sector 102
(corresponding to the first stage of the turbine indicated at 16)
with a single piece. The single piece transition piece 120 may be
formed from two halves or several components welded or joined
together for ease of assembly or manufacture. A sleeve 129 also
transitions directly from the circular combustor head-end 100 to an
aft frame 128 of the transition piece 120 with a single piece. The
single piece sleeve 129 may be formed from two halves and welded or
joined together for ease of assembly. The joint between the sleeve
129 and the aft frame 128 forms a substantially closed end to a
cooling annulus 124. It should be noted that "single" also means
multiple pieces joined together wherein the joining is by any
appropriate means to join elements, and/or unitary, and/or
one-piece, and the like.
[0015] In FIG. 1, there is an annular flow of the discharge air
that is convectively processed over the outside surface of the
transition piece 120. In the example embodiment, the discharge air
flows through the sleeve 129 which forms an annular gap so that the
flow velocities can be sufficiently high to produce high heat
transfer coefficients. The sleeve 129 surrounds the transition
piece 120 forming a flow annulus 124 therebetween. As indicated by
arrows, cross flow cooling air traveling in the annulus 124
continues to flow upstream in a direction perpendicular to cooling
air flowing through holes, slots, openings or other apertures 400
formed about the circumference of the sleeve 129. The sleeve 129
has a series of holes, slots, openings or other apertures 400 that
allow the discharge air to move into the sleeve 129 at velocities
that properly balance the competing requirements of high heat
transfer and low pressure drop. A circled area of the transition
piece 120 will be discussed in more detail in FIGS. 2-3.
[0016] In conventional combustors, a combustor liner and a flow
sleeve are generally found upstream of the transition piece and the
sleeve respectively. However, in the one-piece can combustor of
FIG. 1, the combustor liner and the flow sleeve have been
eliminated in order to provide a combustor of shorter length. The
major components in a one-piece can combustor include a circular
cap 134, an end cover 136 supporting a plurality of fuel nozzles
138, the transition piece 120 and sleeve 129.
[0017] FIG. 2 shows a close-up, perspective view of the transition
piece 120 and the sleeve 129. The sleeve 129 is radially outward
with respect to the transition piece 120 and surrounds the
transition piece 120 forming the flow annulus 124 in between. The
sleeve 129 is formed with a plurality of first apertures or holes
400 to allow compressor discharge air to enter the flow annulus 124
from the exterior space 302. The single-piece transition piece 120
is formed with a plurality of second apertures or effusion holes
200. It must be noted that FIG. 2 shows one example arrangement of
the first and second apertures 200, 400 which is not to be
construed as a limitation on the invention. The formation of the
apertures 200, 400 may be at or extend to other selected areas or
over the entire surface of the transition piece 120 and the sleeve
129 respectively. The apertures 200, 400 may be formed in a
circumferentially dispersed manner or may extend from an upstream
portion to a downstream portion of the transition piece 120 and the
sleeve 129 respectively. Moreover, FIG. 2 shows only one of
multiple possible arrangements in which the plurality of apertures
200, 400 can be patterned. For example, FIG. 2 shows the second
apertures 200 in orthogonal arrangement about one another. In
another example, each second aperture 200 in a row may be slightly
offset relative to second apertures in an adjacent row. The first
apertures 400 are also arranged in rows and columns but the spacing
between the first apertures 400 may differ in a row direction
relative a column direction. The spacing between the first
apertures 400 may also differ from the second apertures 200 as
shown in FIG. 3 in part due to the difference in their sizes. Such
variety in arrangement is within the scope of the present
invention.
[0018] FIG. 3 shows a cross-section through the sleeve 129 and the
transition piece 120. Again, a limited number of apertures 200, 400
are shown on the transition piece 120 and the sleeve 129 for
simplicity of illustration. In particular, FIG. 3 shows a wall 500
that is part of the sleeve 129 and a wall 300 that is part of the
transition piece 120. The wall 500 separates an exterior space 302
from the flow annulus 124. The distance between the wall 300 and
the wall 500 may range from 0.5 inch to 3.0 inches.
[0019] The first apertures 400 are configured to be normal to the
wall 500 such that air flow I is adapted to not strike or directly
impinge an outer surface 300a of the transition piece 120
perpendicularly. The first apertures 400 may be formed directly
above the second apertures 200 (FIG. 3), may be formed to be offset
from the second apertures 200 (FIG. 2) so that no second apertures
are found below the first apertures 400, or may be formed to be
above an area of the wall 300 that in part includes the second
apertures 200 and in part does not include the second apertures
200. In a configuration where the first apertures 400 are not
directly above the second apertures 200, a greater portion of the
air flow I is allowed to flow over an outer surface 300a of the
transition piece 120 rather than enter the apertures 200 upon
arrival at the outer surface 300a.
[0020] FIG. 3 also shows an outer surface 300a and an inner surface
300b of the wall 300. The area above the wall 300 is the flow
annulus 124 while the area below the wall is the interior space 304
of the transition piece 120. A right side of FIG. 3 corresponds to
an upstream area within the turbine while a left side of FIG. 3
corresponds to a downstream area within the turbine. Flow C, made
up of compression discharge air which is cooler than combusted hot
gas, originates from the compressor but approaches the transition
piece 120 in the flow annulus 124 from a downstream area of the
turbine and moves upstream as is typical in a can-annular, reverse
flow combustor. Flow I, also made up of compressor discharge air,
moves upstream in the exterior space 302 from a downstream area of
the turbine and enters the flow annulus 124 through the first
apertures 400. Flow H, made up of hot gas, originates from the
combustion chamber and is directed downstream in the interior space
304 of the transition piece 120.
[0021] As shown in FIG. 3, the second apertures 200 extend from the
outer surface 300a to the inner surface 300b of the wall 300. The
present invention encompasses second apertures 200 formed to be
normal to the wall 300 and formed at an angle .theta. to the wall
300. In FIG. 3, the apertures 200 are shown at the angle .theta.
such that exit portions 200b of the apertures 200 are downstream or
rearward relative to entry portions 200a of the apertures 200. In
one embodiment, the angle .theta. formed by the longitudinal axes
200c of the apertures 200 and a direction 202 that is tangential to
the wall 300 and is pointed downstream may be acute at 30 degrees
and may range from 20 to 35 degrees. However, other smaller and
larger angles are also contemplated. In FIG. 3, the downstream
tangent points to the left. Although the second apertures 200 are
substantially cylindrical, the entry portions 200a and the exit
portions 200b will have elliptical shapes if the apertures 200 are
not normal to the wall 300. However, the apertures 200, 400 may
have a cross section that is not circular and, for example, is
polygonal.
[0022] Another variation of the apertures 200 is that the angular
position of the entry portion 200a may be different from the
angular position of the exit portion 200b on the circumference of
the transition piece 120. Moreover, the exit portion 200b of the
apertures 200 may be upstream or forward relative to the entry
portion 200a of the apertures 200 thereby creating an obtuse angle
between the longitudinal axes of the apertures 200 and the
direction 202.
[0023] In FIG. 3, the second apertures 200 have a substantially
cylindrical geometry with a constant diameter from the entry
portion to the exit portion. In one embodiment, the diameter may be
0.03 inch and alternatively may range from 0.02 inch to 0.04 inch.
However, other dimensions for the apertures 200 are also
contemplated.
[0024] The first apertures 400 also have a substantially
cylindrical geometry with a constant diameter. In one embodiment,
the diameter may range from 0.1 inch to 1.0 inch. However, other
dimensions for the apertures 400 are also contemplated.
[0025] Also, the apertures 200, 400 may gradually increase or
decrease in diameter through the walls 300, 500 respectively.
[0026] The second apertures 200 may be formed on the wall 300 of
the transition piece 120 by laser drilling or other machining
methods selected based on factors such as cost and precision. The
larger dimensions of the first apertures 400 allow for more
tolerance and thus similar or more cost-effective machining methods
may be used to form the apertures 400.
[0027] In FIG. 3, flow I caused by the first apertures or holes 400
cools the transition piece 120 by forming jets of air that do not
strike or directly impinge on the outer surface 300a. Flow C in the
flow annulus provides convective cooling of the transition piece
120 by removing heat while traveling along the outer surface 300a.
Flow E created by the second apertures or effusion holes 200
provides jets of air at all or selected areas of the transition
piece 120 that cool the transition piece 120 as the cooling air
passes through the apertures 200 contacting internal surfaces
therein. Effusion cooling is a form of transpiration cooling. An
aperture that is angled to the wall will have a larger internal
surface area compared to an aperture normal to the wall due to
increased length so that heat transfer is prolonged and greater
cooling of the transition piece 120 can be achieved. Moreover,
after the cool air exits the exit portion 200b of the apertures
200, a layer or film of cooling air is formed adjacent the inner
surface 300b of the wall 300 of the transition piece 120. Formation
of such a layer of cooling air on the inner surface 300b further
cools the transition piece 120. The formation of such a layer is
facilitated by an angled aperture compared to a normal aperture
since the degree of change required in direction by the cool air is
reduced. However, the present invention encompasses the two
variations of normal and angled apertures. Cooling by the film
formed on the inner surface can improve as the hole sizes and
angles are decreased. However, smaller holes are more prone to
blockage from impurities. In comparison, larger holes can cause
excessive penetration of the hot gas stream by the cool air jets
and reduce the efficiency of the turbine. Therefore, such benefits
and drawbacks must therefore be collectively considered when
determining the geometry of the effusion holes.
[0028] The invention has been described with reference to the
example embodiments described above. Modifications and alterations
will occur to others upon a reading and understanding of this
specification. Example embodiments incorporating one or more
aspects of the invention are intended to include all such
modifications and alterations insofar as they come within the scope
of the appended claims.
* * * * *