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United States Patent |
6,182,450
|
Horner
|
February 6, 2001
|
Gas turbine in-line intercooler
Abstract
A gas turbine engine including in-line intercooling wherein compressor
intercooling is achieved without removing the compressor main flow
airstream from the compressor flowpath is described. In an exemplary
embodiment, a gas turbine engine suitable for use in connection with
in-line intercooling includes a low pressure compressor, a high pressure
compressor, and a combustor. The engine also includes a high pressure
turbine, a low pressure turbine, and a power turbine. For intercooling,
fins are located in an exterior surface of the compressor struts in the
compressor flowpath between the outlet of the low pressure compressor and
the inlet of the high pressure compressor. Coolant flowpaths are provided
in the compressor struts, and such flowpaths are in flow communication
with a heat exchanger. In operation, air flows through the low pressure
compressor, and compressed air is supplied from the low pressure
compressor to the high pressure compressor. The fins increase the heat
transfer area between the gas turbine main compressor airflow and the
coolant flow in the struts. Specifically, the flowpaths in the struts
serve as heat sinks for cooling the high temperature compressor mainstream
flow. The cooled airflow is supplied to the inlet of the high pressure
compressor, and the highly compressed air is delivered to the combustor.
Airflow from the combustor drives the high pressure turbine, the low
pressure turbine, and the power turbine. Waste heat is captured by the
boilers, and the heat from the boilers in the form of steam is delivered
to upstream components. The steam could, alternatively, be delivered to a
steam turbine or to other equipment.
Inventors:
|
Horner; Michael W. (West Chester, OH)
|
Assignee:
|
General Electric Company (Cincinnati, OH)
|
Appl. No.:
|
955799 |
Filed:
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October 22, 1997 |
Intern'l Class: |
F02C 007/143 |
Field of Search: |
60/39.07,726,728,39.75,39.161
415/115,116
|
References Cited
U.S. Patent Documents
3628885 | Dec., 1971 | Sidenstick et al. | 416/217.
|
3751909 | Aug., 1973 | Kohler | 60/39.
|
3756020 | Sep., 1973 | Moskowitz et al. | 60/760.
|
3796045 | Mar., 1974 | Foster-Pegg | 60/39.
|
3811495 | May., 1974 | Laing | 165/85.
|
4576547 | Mar., 1986 | Weiner et al. | 415/116.
|
4949544 | Aug., 1990 | Hines | 60/728.
|
5553448 | Sep., 1996 | Farrell et al. | 60/39.
|
5669217 | Sep., 1997 | Anderson | 60/39.
|
5722229 | Mar., 1998 | Provost | 60/39.
|
5722241 | Mar., 1998 | Huber | 60/728.
|
5768884 | Jun., 1998 | Hines | 60/39.
|
Primary Examiner: Kim; Ted
Attorney, Agent or Firm: Hess; Andrew C., Andes; William Scott
Claims
What is claimed is:
1. A gas turbine engine, comprising:
a high pressure compressor;
in-line heat exchanger intercooling apparatus for cooling gas flowing to
said high pressure compressor, said in-line heat exchanger comprising a
plurality of struts located upstream from and in flow communication with
said high pressure compressor, each of said struts comprising a plurality
of fins;
a high pressure turbine located downstream of said compressor; and
a power turbine located downstream of said high pressure turbine.
2. A gas turbine engine in accordance with claim 1 wherein said engine
further comprises a booster located upstream of said high pressure
compressor, and said in-line intercooling apparatus is positioned to cool
gas flowing from an outlet of said booster towards said high pressure
compressor.
3. A gas turbine engine in accordance with claim 1 further comprising a
combustor located downstream of said high pressure compressor, and wherein
cooling by said in-line intercooling apparatus reduces a temperature of
gas at an outlet of said high pressure compressor and at an outlet of said
combustor during operation of said engine.
4. A gas turbine in accordance with claim 3 further comprising a low
pressure turbine, said high pressure turbine, said low pressure turbine,
and said power turbine located downstream of said combustor.
5. A gas turbine engine in accordance with claim 4 further comprising at
least one waste heat recovery steam boiler located downstream of said
power turbine.
6. A gas turbine engine in accordance with claim 1 further comprising a
frame housing upstream of said high pressure compressor, said plurality of
struts extending from said frame, and said in-line cooling apparatus
comprises coolant flow paths in said upstream struts.
7. A gas turbine engine in accordance with claim 6 wherein said plurality
of fins extend axially from said plurality of struts with respect to a
direction of airflow.
8. A gas turbine engine in accordance with claim 6 further comprising a
heat exchanger in flow communication with said coolant flow paths in said
upstream struts.
Description
FIELD OF THE INVENTION
This invention relates generally to gas turbine engines and more
particularly, to an in-line intercooler which eliminates removing the
compressor main flow airstream from the compressor flowpath.
BACKGROUND OF THE INVENTION
Gas turbine engines typically include a compressor for compressing a
working fluid, such as air. The compressed air is injected into a
combustor which beats the fluid, and the fluid is then expanded through a
turbine. The compressor typically includes a low pressure compressor and a
high pressure compressor.
The output of known gas turbine engines may be limited by the temperature
of the working fluid at the output of the high pressure compressor,
sometimes referred to as "T3", and by the temperature of the working fluid
in the combustor outlet, sometimes referred to as "T41". To provide
increased power output and cycle thermal efficiency without exceeding the
T3 and T41 temperature limits, it is known to use an intercooler
positioned in the fluid flow path between the low pressure compressor and
the high pressure compressor.
Known intercoolers generally require the extraction and reintroduction of
the entire gas turbine mainstream flow from and into the main gas turbine
flowpath. Requiring that the entire gas turbine mainstream flow be
extracted and reintroduced into the mainstream flow reduces the thermal
efficiency of the cycle and adds component costs to an engine. Such
intercoolers also introduce pressure losses associated with the removal of
air, the actual cooling of that air, and ducting it back to the
compressor. In addition, and in order to accommodate the entire mainstream
flow, known intercoolers typically must have a large capacity. A
significant amount of water is required by such high capacity
intercoolers, and such high water consumption increases the operational
costs. Of course, a larger capacity intercooler is more expensive, both to
fabricate and operate, than a typical smaller capacity intercooler. Also,
It would be desirable to provide intercooling yet eliminate the requirement
that the entire mainstream flow be extracted and reintroduced into the
main gas turbine flow. It also would be desirable to reduce the required
capacity for an intercooler yet provide substantially the same operational
results.
SUMMARY OF THE INVENTION
These and other objects may be attained by a gas turbine engine including
in-line intercooling wherein compressor intercooling is achieved without
removing the compressor main flow airstream from the compressor flowpath.
In an exemplary embodiment, a gas turbine engine suitable for use in
connection with in-line intercooling includes a low pressure compressor, a
high pressure compressor, and a combustor. The engine also includes a high
pressure turbine, a low pressure turbine, and a power turbine.
For intercooling, fins are located in an exterior surface of the compressor
struts in the compressor flowpath between the outlet of the low pressure
compressor and the inlet of the high pressure compressor. Coolant
flowpaths are provided in the compressor struts, and such flowpaths are in
flow communication with a heat exchanger.
In operation, air flows through the low pressure compressor, and compressed
air is supplied from the low pressure compressor to the high pressure
compressor. The fins increase the heat transfer area between the gas
turbine main compressor airflow and the coolant flow in the struts.
Specifically, the flowpaths in the struts serve as heat sinks for cooling
the high temperature compressor mainstream flow. The cooled airflow is
supplied to the inlet of the high pressure compressor, and the highly
compressed air is delivered to the combustor. Airflow from the combustor
drives the high pressure turbine, the low pressure turbine, and the power
turbine. Waste heat is captured by the boilers and the heat from the
boilers in the form of steam is delivered to upstream components.
The in-line intercooling provides an advantage in that the temperature of
the airflow at the outlet of the high pressure compressor (temperature T3)
and the temperature of the airflow at the outlet of the combustor
(temperature T41) are reduced as compared to such temperatures without
intercooling. Specifically, the combination of the fins and coolant flow
through the struts extract heat from the hot air flowing into and through
the high pressure compressor, and by extracting such heat from the air
flow, the T3 and T41 temperatures are reduced and compressive horsepower
is reduced. Reducing the T3 and T41 temperatures provides the advantage
that the engine is not T3 and T41 constrained, and therefore, the engine
may operate at higher output levels than is possible without intercooling.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of a gas turbine engine including
in-line intercooling in accordance with one embodiment of the present
invention.
FIG. 2 is a cross section through a portion of the front frame structure
for the high pressure compressor shown in FIG. 1.
FIG. 3 illustrates air flow by one of the struts shown schematically in
FIG. 2.
FIG. 4 is a cross sectional view through the strut shown in FIG. 3.
FIG. 5 is a side view of a portion of the strut shown in FIG. 3.
FIGS. 6a, 6b, 6c, and 6d illustrate alternative embodiments of the shapes
of the strut fins shown in FIG. 5.
FIG. 7 is a cross sectional view through a strut in accordance with another
embodiment of the present invention.
FIG. 8 is a cross sectional view through a strut in accordance with yet
another embodiment of the present invention.
FIG. 9 is a cross sectional view through a strut in accordance with still
yet another embodiment of the present invention.
DETAILED DESCRIPTION
Set forth below are exemplary configurations of in-line intercooling in
accordance with various embodiments of the present invention. Initially,
it should be understood that although specific implementations are
illustrated and described, in-line intercooling can be practiced using
many alternative structures and in a wide variety of engines. In addition,
and as described below in more detail, in-line intercooling can be
performed at various locations in the engine, and is not limited to
practice at an intermediate location between the low pressure compressor
and the high pressure compressor as described below.
Referring now specifically to the drawings, FIG. 1 is a schematic
illustration of a gas turbine engine 10 which, as is well known, includes
a low pressure compressor 12, a high pressure compressor 14, and a
combustor 16. Engine 10 also includes a high pressure turbine 18, a low
pressure turbine 20, and a power turbine 22.
In-line intercooling apparatus 24 is provided for cooling the airflow from
the low pressure compressor to an inlet of high pressure compressor 14.
Further details regarding various embodiments of apparatus 24 are set
forth below. For purposes of FIG. 1, however, it should be understood that
apparatus 24 is in-line with high pressure compressor 14 in that the
airflow to compressor 14 need not be extracted and reintroduced into the
main gas flow.
Waste heat boilers 28, 30, and 32 are located downstream of power turbine
22. As is known in the art, feed water is supplied to boilers 28, 30, and
32 via a feedwater line 34, and water in the form of steam is communicated
from boilers 28, 30, and 32 to various upstream components. Particularly,
steam from boiler 28 is provided to an inlet 36 of combustor 16, steam
from boiler 30 is provided to an inlet of low pressure turbine 20 and an
inlet of power turbine 22, and steam from boiler 32 is provided to a last
stage of power turbine 22. Except for in-line injection apparatus 24, the
various components of turbine 10 are known in the art.
In operation, air flows through low pressure compressor 12, and compressed
air is supplied from low pressure compressor 12 to high pressure
compressor 14. In-line intercooling apparatus 24 cools the air flow
supplied to high pressure compressor 14, and the air is further compressed
by high pressure compressor 14. The highly compressed air is delivered to
combustor 16. Airflow from combustor 16 drives high pressure turbine 18,
low pressure turbine 20, and power turbine 22. Waste heat is captured by
boilers 28, 30, and 32, and the waste heat steam is delivered to upstream
components coupled to boilers 28, 30 and 32 as described above.
In-line intercooling apparatus 24 provides the advantage that the airflow
to high pressure compressor need not be extracted and reintroduced into
the main airflow for intercooling. Rather, with apparatus 24, intercooling
is provided within the main airflow. Therefore, the thermal efficiency of
engine 10 is believed to be improved, and pressure losses are believed to
be less, as compared to an engine using a known intercooler. Further, less
coolant is believed to be used in connection with apparatus 24 than in
known large capacity intercoolers.
FIG. 2 is a cross section through a portion of a front frame 50 for high
pressure compressor 26 and illustrating various aspects of in-line
intercooling apparatus 24. Specifically, frame 50 includes an outer shell
52 and an inner shell 54, and a plurality of struts 56 extend from and
between outer and inner shells 52 and 54. Shells 52 and 54 are
substantially cylindrical, and the main airflow through engine 10 is
between shells 52 and 54.
In accordance with the present invention, struts 56 include a plurality of
fins 58. Struts 56 and fins 58 are shown schematically in FIG. 2. Fins 58
extend from the exterior surface of struts 56 and increase the heat
transfer area between the gas turbine main compressor airflow and, as
described below, coolant flowing through struts 56.
To enhance intercooling, front frame (including struts) 50 may be
fabricated from a high thermal conductivity material, such as aluminum or
an aluminum alloy. Such material is believed to provide a very high heat
transfer effectiveness for struts 56 and fins 58.
FIG. 3 illustrates air flow by one strut 56. As shown in FIG. 3, a bleed
door or perforated plate 60 is located on outer shell 56 and allows air to
bleed from between inner and outer shells 52 and 54. Such bleed flow often
is required in the operation of a two-shaft aeroderivative gas generator.
Further, an inboard coolant manifold 62 may be secured to strut 56. Such
manifold 62 would, of course, be connected in a coolant return circuit
directing the flow to a heat exchanger.
FIG. 4 is a cross sectional view through strut 56 shown in FIG. 3. Strut 56
includes fins (only one fin is visible in FIG. 4) 58 and inner coolant
passages 64 and 65 in strut main body 66 which operates as a heat sink for
the high temperature compressor mainstream flow. More particularly,
coolant is supplied to passage 64, and as such coolant is heated, such
heated coolant is replaced by cooled coolant. Heat is removed from the
coolant by the heat exchanger. Alternatively, the coolant can be
discharged or to a second heat exchange fluid (e.g., air, fuel, or water).
As a result of such heat transfer, heat is extracted from the main airflow
prior to entering high pressure compressor 14 (FIG. 1).
FIG. 5 is a side view of a portion of strut 56. Line A--A shown in FIG. 3
generally indicates the location at which fins 58 may need to be
terminated if compressor bleed flow is required. Such termination of fins
58 would permit unobstructed flow to bleed doors or passages. In addition,
parameters such as fin spacing S, fin thickness T, fin height H, the fin
profile shape, and circumferential fin spacing CS (FIG. 2) are selected to
balance operating and manufacturing considerations such as the heat
transfer rate to achieve the desired level of cooling of mainstream air,
ease of manufacture, manufacturing cost, durability, and achieving an
acceptable level of mainstream pressure loss.
With respect to a geometric shape of fins, FIGS. 6a, 6b, 6c, and 6d
illustrate alternative embodiments. An ideal fin shape 68 is shown in FIG.
6a. Such a fin shape is believed to provide preferred results for
aerodynamic considerations and heat transfer. Such a fin shape may,
however, be difficult to manufacture. FIG. 6b illustrates a triangular
shaped fin 70 with a rounded edge 72, FIG. 6c illustrates a rectangular
shaped fin 74, and FIG. 6d illustrates a bullet shaped fin 76. These fin
shapes are believed to at least merit consideration when selecting a fin
shape for a specific application.
Rather than being separate, it is contemplated that the fins could be
connected between adjacent struts. With such a configuration, continuous
rings would be located around the front frame annulus. Of course, many
other variations of the fins are possible.
In addition, and referring to FIGS. 7, 8, and 9, alternative configurations
of struts also are possible. Fins 80 are illustrated in phantom in FIGS.
7, 8, and 9. For example, FIG. 7 is a cross sectional view through a strut
82 in accordance with another embodiment of the present invention. Strut
82 includes an inner passage 84 formed by an inner member 86 which may
include impingement holes 88 therethrough. An outer member 90 surrounds
inner member, and coolant (e.g., liquid or gas) flows through inner member
86 and through impingement holes 88 to a space 92 between inner and outer
members 86 and 90.
Another strut 94 is shown in FIG. 8. Particularly, radial openings 96 are
formed in a strut train body 98. Coolant flows through such radial
openings 96 for transferring heat from the main airflow through the engine
to the coolant.
In FIG. 9, a strut 100 includes a main body 102 having an inner coolant
passages 104 and 105 with turbulator ribs 106 formed on their interior
surfaces. Such ribs 106 increase the heat transfer area between strut 100
and coolant flowing through passages 104 and 105.
Intercooling provided by the above described in-line intercooling apparatus
extracts heat from the air compressed in the low pressure compressor,
which reduces both the temperature and volume of air entering the high
pressure compressor. Such reduction in temperature reduces both the T3 and
T41 temperatures while reducing compressor required horsepower, and
greater output can be achieved. Such intercooling also provides the
advantage that the airflow to high pressure compressor need not be
extracted and reintroduced into the main airflow for intercooling. Rather,
with the in-line apparatus, intercooling is provided within the main
airflow. Therefore, the thermal efficiency of the engine is believed to be
improved, and pressure losses are believed to be less, as compared to an
engine using a known intercooler. Further, less coolant is believed to be
used in connection with in-line apparatus than in known large capacity
intercoolers.
From the preceding description of various embodiments of the present
invention, it is evident that the objects of the invention are attained.
Although the invention has been described and illustrated in detail, it is
to be clearly understood that the same is intended by way of illustration
and example only and is not to be taken by way of limitation. Accordingly,
the spirit and scope of the invention are to be limited only by the terms
of the appended claims.
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