U.S. patent application number 12/165800 was filed with the patent office on 2010-01-07 for inlet air heating system for a gas turbine engine.
Invention is credited to Craig F. Smith.
Application Number | 20100003123 12/165800 |
Document ID | / |
Family ID | 41136885 |
Filed Date | 2010-01-07 |
United States Patent
Application |
20100003123 |
Kind Code |
A1 |
Smith; Craig F. |
January 7, 2010 |
INLET AIR HEATING SYSTEM FOR A GAS TURBINE ENGINE
Abstract
A gas turbine engine has an inlet for delivering air into a
compressor section. The compressor section is connected to feed air
into a combustion section, wherein the air mixes with fuel and
combusts. The combustion section is connected to turbine rotors
such that products of combustion can pass over the turbine rotors
to drive the turbine rotors. An exhaust communicates with the
turbine sections to receive the products of combustion. A bleed tap
communicates the exhaust to the inlet. A control controls the
amount of exhaust gasses tapped into the inlet to achieve desired
operating conditions.
Inventors: |
Smith; Craig F.; (Ashford,
CT) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS/PRATT & WHITNEY
400 WEST MAPLE ROAD, SUITE 350
BIRMINGHAM
MI
48009
US
|
Family ID: |
41136885 |
Appl. No.: |
12/165800 |
Filed: |
July 1, 2008 |
Current U.S.
Class: |
415/116 |
Current CPC
Class: |
F02C 3/34 20130101; F02C
1/08 20130101; F05D 2270/082 20130101 |
Class at
Publication: |
415/116 |
International
Class: |
F04D 31/00 20060101
F04D031/00 |
Claims
1. A gas turbine engine comprising: an inlet for delivering air
into a compressor section; the compressor section connected to feed
air into a combustion section, wherein the air mixes with fuel and
combusts, and the combustion section connected to a turbine section
such that products of combustion can pass over a turbine rotor in
the turbine section to drive the turbine rotor; an exhaust for
communicating with the turbine section to receive the products of
combustion; and a tap communicating said exhaust to said inlet, and
a control for controlling an amount of exhaust gas tapped into the
inlet to achieve desired operating conditions.
2. The gas turbine engine as set forth in claim 1, wherein the
amount of gas tapped from the exhaust to the inlet is controlled to
achieve a desired inlet temperature at the inlet.
3. The gas turbine engine as set forth in claim 2, wherein
temperature sensors sense the temperature at the inlet and the
exhaust and send signals to the control.
4. The gas turbine engine as set forth in claim 1, wherein the
control controls a blower to control the amount of exhaust gas
passing from the exhaust to the inlet.
5. The gas turbine engine as set forth in claim 1, wherein the
control controls a damper to control the amount of exhaust gas
passing from the exhaust to the inlet.
6. The gas turbine engine as set forth in claim 1, wherein the
turbine rotors drive a generator to create electricity.
7. The gas turbine engine as set forth in claim 1 wherein the
combustion section is of a dry low NOx type.
8. A method of operating a gas turbine engine comprising the steps
of: (a) delivering air from an inlet to a compressor section; (b)
compressing air and delivering the air into a combustion section,
mixing the compressed air with fuel and combusting the mixture,
passing products of the combustion over turbine rotors to drive the
turbine rotors; (c) receiving the products of combustion at an
exhaust; and (d) tapping gas from said exhaust to said inlet, and
controlling the amount of gas tapped to the inlet to achieve
desired operating conditions in the gas turbine engine.
9. The method as set forth in claim 8, wherein the amount of tapped
gas is controlled to achieve a desired inlet temperature at the
inlet;
10. The method as set forth in claim 8, wherein the turbine rotors
drive a generator to create electricity.
11. A system for controlling the power provided by a gas turbine
engine comprising: a tap line to tap exhaust gas from an exhaust of
a gas turbine engine, and deliver the tapped exhaust gas to an
inlet of the gas turbine engine; and a control for controlling an
amount of tapped exhaust gas that is delivered to the inlet of the
gas turbine engine to achieve desired operating conditions.
12. The system as set forth in claim 11, wherein the amount of gas
tapped from the exhaust to the inlet is controlled to achieve a
desired inlet temperature at the inlet.
13. The system as set forth in claim 12, wherein temperature
sensors sense the temperature at the inlet and the exhaust and send
signals to the control.
14. The system engine as set forth in claim 11, wherein the control
controls a blower to control the amount of exhaust gas passing from
the exhaust to the inlet.
15. The system as set forth in claim 11, wherein the control
controls a damper to control the amount of exhaust gas passing from
the exhaust to the inlet.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to gas turbine
engines and more particularly to an inlet air heating system of the
engine and method of operating the same.
[0002] Gas turbine engines are known, and typically include an
inlet through which air passes to a compressor section. The air is
compressed in the compressor section and passed downstream into a
combustion section. In the combustion section, air is mixed with
fuel and burned. Products of this combustion pass downstream across
turbine rotors, to drive the rotors. A good deal of control is
included in modern gas turbine engines.
[0003] One recent advancement in gas turbine engines is the
so-called dry low NOx or "DLN" combustion systems. These are often
utilized in industrial gas turbine engines to achieve very low
levels of NOx emissions, without any need for water injection.
These engines typically have a very narrow operating range over
which emissions are kept low.
[0004] One way to increase the operating range is a concept known
as inlet bleed heat. Inlet bleed heat involves bleeding off
compressor discharge air and injecting it into the inlet air
passing into the gas turbine engine. This heat increases inlet air
temperature and reduces the power provided by the gas turbine
engine. The use of the bleed air reduces the power in that as the
inlet temperature increases, the provided power decreases.
Unfortunately, bleeding off compressor discharge air reduces engine
efficiency.
SUMMARY OF THE INVENTION
[0005] A gas turbine engine has an inlet for delivering air into a
compressor section. The compressor section is connected to feed air
into a combustion section, where the air mixes with fuel and
combusts. The combustion section is connected to turbine rotors
such that products of combustion can pass over the turbine rotors
to drive the turbine rotors. An exhaust communicates with the
turbine sections to receive the products of combustion. A bleed tap
communicates the exhaust to the inlet. A control controls the
amount of exhaust gasses tapped into the inlet to achieve desired
operating conditions without a loss in engine efficiency. Also, an
inventive method and a system for reducing the power from a gas
turbine engine are claimed.
[0006] These and other features of the present invention can be
best understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic view of a gas turbine engine
incorporating a unique inlet air heating system.
[0008] FIG. 2 shows a second embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0009] A gas turbine engine 20 is illustrated in FIG. 1. An inlet
22 delivers air to a low pressure compressor section 24, and
downstream to a high pressure compressor section 26. Air from the
compressor section 26 passes into a combustion section 27, and is
mixed with fuel and burned. Preferably, the combustion section 27
is of a dry low NOx premix (DLN) type wherein fuel and air are
premixed prior to combustion to assure flame temperatures are kept
uniformly low to prevent formation of NOx. Products of this
combustion pass over a high pressure turbine 28, and a low pressure
turbine 30, driving the turbine rotors 128 and 130. The turbine
rotors in turn drive compressor rotor 126 and compressor rotor 124,
respectively. Downstream of the turbine sections the products of
combustion pass into an exhaust 32. As shown, a tap line 34 taps a
portion of the exhaust gas through a blower 36, and into a tap line
38. The tap line 38 bleeds gas into inlet 22 in controlled amounts.
Although no fan section is shown, the present invention also
extends to engines including a fan located upstream of the
compressor sections 26, 24.
[0010] The amount of gas bled into the inlet 22 is controlled to
achieve a desired amount of power to be delivered from the turbine
sections 28 and 30. As shown schematically in FIG. 1, the turbine
sections 28 and 30 deliver power to a generator 40.
[0011] In some applications, if the pressure difference between the
exhaust 32 and the inlet 22 is sufficient, blower 36 may not be
necessary. As an example, if a heat recovery steam boiler is
included, the pressure difference might be sufficient. Instead, a
simple damper 42, as shown schematically in FIG. 2, may be
sufficient. As should be appreciated, the damper is rotated under
the control of a motor 44 to control the amount of air delivered
from exhaust 32 to inlet 22.
[0012] Notably, the exhaust gasses may have corrosive materials
produced when burning fuel. Thus, with this system bleeding air
from the exhaust through the lines 34, 38, the material and
coatings of the turbine sections 28 and 30, and even perhaps the
compressor sections 24 and 26, should be selected to resist any
potential corrosion issues.
[0013] By recirculating gas from the exhaust 32 to the inlet 22,
the temperature of the inlet air can be increased, and the oxygen
content reduced. Reducing the oxygen content may further reduce NOx
emissions.
[0014] A worker of ordinary skill in this art would recognize how
much air to deliver from the exhaust 32 to the inlet 22 dependent
upon the relative temperatures at the two locations preferably
measured by sensor 39 and sensor 41, respectively. Sensors 39, 41
send signals to a control 43 for the blower motor 36, or the damper
motor 44. Control 43 can be any appropriate processor. Dependent on
the desired temperature, and operating temperature, the air
delivered to the compressor 24 can be between zero and twenty
percent exhaust gas.
[0015] Also, the tap lines 34 and 38, along with the blower motor
36, or damper 42, can be connected to existing gas turbine
engines.
[0016] Although an embodiment of this invention has been disclosed,
a worker of ordinary skill in this art would recognize that certain
modifications would come within the scope of this invention. For
that reason, the following claims should be studied to determine
the true scope and content of this invention.
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