U.S. patent number RE38,831 [Application Number 10/991,323] was granted by the patent office on 2005-10-18 for gas turbine having water spray injection control.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Fumiyuki Hirose, Nobuyuki Horii, Yasuhiro Katoh, Takaaki Kuwahara, Hidetaro Murata, Tetsuo Sasada, Isao Takehara, Motoaki Utamura.
United States Patent |
RE38,831 |
Horii , et al. |
October 18, 2005 |
Gas turbine having water spray injection control
Abstract
A gas turbine comprises a compressor for compressing a gas
supplied therein and discharging the compressed gas, a combustor in
which the discharged gas from the compressor and a fuel are
combusted, a turbine to be driven by a combustion gas from the
combustor, and a water injection unit which injects water into the
gas to be supplied to the compressor, thereby lowering the
temperature of the gas to be introduced into the compressor to a
temperature lower than the atmospheric temperature, and causing
water droplets having been injected in the gas and within the
compressor to be vaporized while flowing down therein, wherein the
quantity of water spray injection is controlled while monitoring
operational conditions of the gas turbine.
Inventors: |
Horii; Nobuyuki (Hitachi,
JP), Takehara; Isao (Hitachi, JP), Murata;
Hidetaro (Hitachi, JP), Utamura; Motoaki
(Hitachi, JP), Kuwahara; Takaaki (Hitachi,
JP), Sasada; Tetsuo (Hitachi, JP), Hirose;
Fumiyuki (Hitachi, JP), Katoh; Yasuhiro
(Hitachinaka, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
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Family
ID: |
27474584 |
Appl.
No.: |
10/991,323 |
Filed: |
November 18, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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156949 |
May 30, 2002 |
6530210 |
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855678 |
May 16, 2001 |
6711888 |
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106077 |
Jun 29, 1998 |
6260350 |
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Reissue of: |
244441 |
Sep 17, 2002 |
06568168 |
May 27, 2003 |
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Foreign Application Priority Data
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Jun 30, 1997 [JP] |
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9-174667 |
Jun 30, 1997 [JP] |
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9-174668 |
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Current U.S.
Class: |
60/39.3;
60/39.53 |
Current CPC
Class: |
F02C
7/1435 (20130101) |
Current International
Class: |
F02G
3/00 (20060101); F02C 7/00 (20060101); F02G
003/00 (); F02C 007/00 () |
Field of
Search: |
;60/39.3,39.53 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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781 909 |
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Jul 1997 |
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EP |
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61-37794 |
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Nov 1986 |
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JP |
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61-283723 |
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Dec 1986 |
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JP |
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2-211331 |
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Aug 1990 |
|
JP |
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56-43433 |
|
Apr 1991 |
|
JP |
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5-195809 |
|
Aug 1993 |
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JP |
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6-10702 |
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Jan 1994 |
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JP |
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7-97933 |
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Apr 1995 |
|
JP |
|
Other References
Boggio, "Benefits of Compressor Inlet Air Cooling for Gas Turbine
Co-generation Plants", ASME, 95-GT-311, Jun. 1995. .
Poletavkin, "Cycles and Thermal Circuits of Steam-gas Turbine
Installations, with Cooling of the Gas During Compression by the
Evaporation of Injected Water", Institute of High Temperature,
Academy of Sciences of the USSR, May 1970. .
Johnson, Sr., "The Theory and Operation of Evaporative Coolers for
Industrial Gas Turbine Installations", Journal of Engineering for
Gas Turbines and Power, Apr. 1989. .
Nolan et al, "Gas Turbine Performance Improvement Direct Mixing
Evaporative Cooling System", ASME 90-GT-368, Jun. 1990..
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Primary Examiner: Freay; Charles G.
Attorney, Agent or Firm: Mattingly, Stanger, Malur &
Brundidge, P.C.
Parent Case Text
This is a divisional application of U.S. Ser. No. 10/156,949, filed
May 30, 2002, now U.S. Pat. No. 6,530,210, which is a divisional
application of U.S. Ser. No. 09/855,678, filed May 16, 2001.[.now
abandoned.]. .Iadd., now U.S. Pat. No. 6,711,888, which is a
divisional application of U.S. Ser. No. 09/106,077, filed Jun. 29,
1998, now U.S. Pat. No. 6,260,350.Iaddend..
Claims
What is claimed is:
1. A gas turbine having a compressor for compressing air supplied
thereto and discharging the compressed air, a combustor for
combusting the compressed air from said compressor and a fuel and a
gas turbine to be driven by a combustion gas from said combustor,
comprising: a premixer provided in said combustor for burning
premixed gas formed by premixing fuel and air; an injection unit,
arranged within an intake air duct at an upstream side of said
compressor and constructed so that water droplets are sprayed into
the air to be supplied to the compressor to decrease the
temperature of the air to be supplied into said compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into said compressor with the air having
been decreased in temperature are evaporated during passage through
said compressor; and a controlling unit for controlling an
adiabatic efficiency of said compressor and controlling a quantity
of water spray on the basis of the adiabatic efficiency, during
operation of spraying water droplets.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a gas turbine and more
particularly, to a gas turbine which injects water droplets into an
intake air of a compressor of the gas turbine.
A conventional gas turbine is caused to drop its output in a summer
season when the temperature increases, therefore, various
arrangements have been proposed as a method to recover the dropped
output.
JP-A Laid-Open No. 7-97933, JU No. 61-37794, or JP-A Laid-Open No.
5-195809 disclose that the intake air of the compressor is
cooled.
Further, JP-A Laid-Open No. 61-283723 discloses that water is
supplied from the inlet of the compressor and from the intermediate
stage of the compressor in a combined system of a gassification
furnace and a gas turbine.
Further, JU-A No. 56-43433 discloses that a supply port through
which to supply water droplets is provided in its compressor, and
JP-A No. 2-211331 discloses a gas turbine which is provided with
two types of compressors of a high pressure and a low pressure, and
an intermediate cooler which is provided between these two types of
compressors. Still further, JP-A No. 6-10702 discloses a technique
to inject water into an intermediate section between an
upper-stream compressor stage and a down-stream compressor stage in
a compressor group having a plurality of compressor stages in order
to reduce power consumption.
However, what are disclosed by these related arts of JP-A No.
7-97933, JU No. 61-37794 or JP-A No. 5-195809 are addressed simply
to dropping temperatures of intake air to be admitted into the
compressor so as to be able to improve its output. JP-A No.
61-283723 merely discloses vaporization of water droplets in the
compressor and utilization thereof as a medium to cool the turbine
blades, and as a consequence, improvement of turbine cycle
characteristics.
Further, JP-A No. 2-211331 discloses the gas turbine which is
provided with an intermediate cooler which is provided between the
two types of compressors of high pressure and low pressure, and
wherein means for detecting a temperature and a humidity at the
inlet of the high pressure compressor are provided, and a feed
water flow to the intermediate cooler is controlled. However, this
control does not teach nor suggest water injection into the
compressor itself, and is not concerned with control of humidity at
the inlet of the compressor.
In consideration of an actual operation of a gas turbine or a
combined cycle using a gas turbine and a steam turbine, there is
required a development of a system which can realize a safety
operation of the gas turbine while always ensuring protection of
the gas turbine itself, and which can improve its output and
thermal efficiency using a simple arrangement.
SUMMARY OF THE INVENTION
An object of the invention is to provide a gas turbine which can
realize improvements both on its output and thermal efficiency
through injection of liquid droplets into intake air introduced to
the inlet of the compressor using simple facilities suitable for
actual application, and also a safety operating system using the
same.
A first present invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged at an upstream side of the compressor and
constructed so that water droplets are sprayed into the air to be
supplied to the compressor to lower the temperature of the air to
be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, a detection
unit for detecting the humidity of air to be supplied to the
compressor, and a controlling unit for controlling a quantity of
water droplets to be sprayed from the injection unit on the basis
of a signal from the detection unit.
For example, it is possible to control a spray quantity of the
liquid droplets according to the detected signal.
The humidity of intake air at the upstream side of the injection
unit, for example, is detected and a spray quantity of the liquid
droplets is controlled to be more when the humidity is low than
when it is high.
Further, it is preferable for the control unit to have a detection
unit for detecting the temperature and humidity of air supplied to
the compressor and control a spray quantity of water droplets
sprayed from the injection unit on the basis of the detection
signal. By detecting the temperature of air at the upstream side of
the injection unit, the spray quantity of water droplets is
controlled to be more at a lower temperature than at a higher
temperature, and the spray quantity of water droplets is controlled
to be more when the humidity of air at the upstream side of the
injection unit is lower than when the humidity is higher than when
low.
Further, it is possible to control the above-mentioned spray
quantity on the basis of output, etc. and use it as a limit value
of the spray quantity on the basis of the above-mentioned detection
signal. The control unit has a limit value set for a spray quantity
of water droplets from the injection unit on the basis of the
detection signal and controls the spray quantity to be within the
above-mentioned limit value.
For example, a spray quantity of water droplets is determined
according to output. In this case, the temperature of intake air at
the upstream side of the injection unit is detected, the
above-mentioned limit value is made higher when the temperature is
lower than when high, the above-mentioned limit value is made
higher when the humidity of intake air at the upstream of the
injection unit is lower than when high, and a spray quantity of the
water droplets is controlled (corrected) not to exceed the limit
value.
Thereby, the soundness of the compressor is secured and a high
output operation of the gas turbine can be executed. Since a water
spray quantity is adjusted by considering the humidity of intake
air when water droplets are injected into the intake air, a
quantity of water droplets introduced into the compressor without
evaporating until the injected water droplets reach the compressor
inlet can be controlled to be a proper quantity, and a quantity of
water droplets having been evaporated until they reach the
compressor inlet and a quantity of water droplets having been
evaporated within the compressor can be suitably controlled.
Therefore, the gas turbine can be operated at a high output while
securing the soundness of the plant, taking into consideration an
influence on the compressor.
Thereby, it is possible to practice water injection while securing
a safety operation of the gas turbine main body.
For example, when detecting means for detecting the temperature and
humidity of gas at the upstream side of the compressor is provided,
a water spray quantity limit value related to the temperature and
humidity is set and the water quantity is controlled so that a real
effective water spray quantity does not exceed the above-mentioned
water spray quantity limit value during a water spraying operation,
such cases can be considered that the effective water spray
quantity is calculated from the humidity of gas at the compressor
discharge portion and the humidity of gas at the upstream side of
the injection unit and that it is calculated from a water quantity
indication value of the water supply system and a drain occurrence
amount in the intake air duct of the upstream side of the
compressor. However, any case can be taken. The humidity of
compressor discharge air can be measured by continuously drafting
air into a tank for sampling which is provided with a humidity
detecting means.
A second invention is a gas turbine, having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, and characterized by comprising
an injection unit, arranged at an upstream side of the compressor
and constructed so that water droplets are sprayed into the air to
be supplied to the compressor to lower the temperature of the air
to be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, a detection
unit for detecting the opening of a compressor inlet vane, arranged
in the compressor, and a controlling unit for controlling a
quantity of water droplets to be sprayed from the injection unit on
the basis of a signal from the detection unit.
For example, it is possible to set a limit value of a quantity of
water droplets sprayed from the injection unit on the basis of the
above-mentioned detection signal and control the spray quantity to
be within the limit value. It is possible to set the
above-mentioned limit value to be larger when the above-mentioned
compressor vane opening is larger than when small. Since a quantity
of air decreases according to a change in the guide vane angle or
opening, a quantity of water is decreased as well.
Thereby, it is possible to inject a quantity of water corresponding
to a quantity of air at the compressor inlet at the time of partial
load operation. Further, it is possible to secure the soundness of
the apparatus and devices of the plant at the time of partial load
operation.
There are cases such that a quantity of air introduced into the
compressor is decreased by throttling the guide vane of the
compressor and that the quantity of air decreases because of a rise
in atmospheric temperature, however according to the present
construction, it is possible to inject a suitable quantity of water
according to an increase or decrease in an intake air quantity at
the time of a partial load operation. It is possible to suppress a
condition such as an excessive amount of water spray, and operate
the gas turbine at a high output while protecting the apparatus and
devices.
Further, it is preferable to detect the above-mentioned compressor
inlet guide vane angle and the compressor inlet air quantity and
limit the spray quantity of water droplets according to the intake
air quantity. In this case, it is further preferable to have
determined the water droplet spray quantity according to ratios
thereof to the compressor inlet air quantity because it is possible
to influence, on the water droplet spray quantity, difference
between individual machines of the same kind, a decrease in a
compressor intake air quantity due to aged deterioration and a
scale ratio in machine kinds of similar figures.
A third invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged at an upstream side of the compressor and
constructed so that water droplets are sprayed into the air to be
supplied to the compressor to lower the temperature of the air to
be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, and a
controlling unit for controlling the injection unit so as to stop
injection of water droplets from the injection unit at time of
starting of the gas turbine and start injection of water droplets
from the injection unit after the gas turbine has come into a rated
operation.
A shift of an operation of the gas turbine to a rated operation can
be detected by a prescribed opening of the compressor inlet guide
vane (an opening at time of normal operation, a full opening,
etc.). Further, it can be detected by coming into an operation of a
constant combustion temperature.
After the shift to the rated operation, for example, when a
difference occurs between a required output value and a real output
value, it is possible to operate by controlling the above-mentioned
water droplet spray quantity so that the real output becomes a
required output.
Thereby, it is possible to provide a gas turbine with a safe output
increasing mechanism by water spray while protecting the gas
turbine.
Even under the condition the gas turbine is operated at a constant
partial load, it is possible to control so as to execute a water
spray operation. Thereby, the thermal efficiency at the time of a
partial load operation can be improved.
A fourth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged at an upstream side of the compressor and
constructed so that water droplets are sprayed into the air to be
supplied to the compressor to lower the temperature of the air to
be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into said compressor with the air having been lowered in
temperature are evaporated during passage through the compressor,
the injection unit having a plurality of spray nozzles for spraying
water droplets, and a controlling unit for controlling the
injection unit so that the number of the spraying nozzles spraying
water droplets more than a prescribed quantity of water droplets
becomes more than the number of the spraying nozzles spraying water
droplets less than the prescribed quantity of water droplets.
For example, the above-mentioned injection unit has a water supply
apparatus, a water supply main pipe line for supplying water from
the water supply apparatus, a water supply header distributing
water supplied from the water supply main pipe to a plurality of
water supply pipes, and nozzles arranged on water supply pipes in
which water distributed by the header flows for spraying the water
droplets, and it can be further provided with a control unit which
control so that the number of water supply pipes for supplying the
water when the water droplet spray quantity is larger than a
prescribed amount becomes more than the number of water supply
pipes supplying the water when the water droplet spray quantity is
smaller than the prescribed quantity.
Further, in the case where the above-mentioned spray nozzle is a
two-fluid nozzle, the spray nozzle can be arranged so as to
communicate with an air supply main pipe supplying air from the air
supply apparatus, an air supply header distributing the air
supplied from the air supply main pipe and air supply pipes in
which air distributed by the header flows.
Further, for example, the construction of the above-mentioned water
supply header of the injection unit can be constructed as
follows:
The injection unit comprises a water supply apparatus, a water
supply main pipe supplying water from the water supply apparatus, a
main water supply header distributing water supplied from the water
supply main pipe to a plurality of water supply branch pipes, an
auxiliary water supply header distributing water flowing the water
supply branch pipes to a plurality of water supply pipes, and
nozzles, arranged on the water supply pipes in which water branched
by the auxiliary water supply header flows, for spraying water
droplets.
Thereby, even when the spray quantity of water droplets increases
and decreases, it is possible to stably spray water droplets and an
operation of high output can be carried out with the stable water
spray.
Further, it is possible to suppress non-uniformity in the water
quantity supplied to the spray nozzles, etc.
A fourth invention is characterized by providing a water supply
flow regulation valve on an upstream side of the water supply
header or water supply main header and controlling a water spray
quantity by the water supply flow regulation valve. Thereby, water
can be supplied simultaneously to the water spray nozzles at a
fixed flow rate.
Further, with respect to a control of a flow rate, it is possible
to provide a feed water flow regulation valve each between a
downstream side of the feed water main header and the upstream side
of the feed water auxiliary headers, and control a water spray
quantity by the feed water flow regulation valve according to a
required water spray quantity. It also is possible to control the
water spray quantity by changing the number of the operating feed
water auxiliary headers according to the water spray quantity.
Further, it is possible to provide a feed water regulation valve
between a downstream side of the feed water main header or feed
water auxiliary header and an upstream side of the spray water
piping and control a water spray quantity thereby. Further, it is
possible to provide a feed water flow regulation valve between a
downstream side of the spray water piping and an upstream side of
the spray nozzles and control the water spray quantity from the
spray nozzles thereby.
A fifth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged at an upstream side of the compressor and
constructed so that water droplets are sprayed into the air to be
supplied to the compressor to lower the temperature of the air to
be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, the injection
unit having a water supply system, an air supply system and a spray
nozzle for being supplied with water and air from the water supply
system and air supply system and spraying water droplets, and a
controlling unit for controlling the water supply quantity and air
supply quantity so as to suppress variation between a ratio of
water and air supplied to the spray nozzle when the water droplet
supply quantity is small and a ratio of water and air supplied to
the spray nozzle when the water droplet supply quantity is
large.
In this manner, an air supply quantity is controlled according to a
change in a water supply quantity so that a ratio of air and water
becomes constant (so that variation in the ratio is suppressed)
according to a water spray quantity.
Thereby, it is possible to obtain water droplets of prescribed
diameter while keeping the air quantity small (it is preferable in
a case where a water quantity is relatively small). In a case where
air is taken from the compressor, it is possible to supply a larger
amount of air from the taken air to the combustor, and an operation
of high output or high efficiency can be carried out even if the
water droplet spray quantity is changed.
A sixth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged at an upstream side of the compressor and
constructed so that water droplets are sprayed into the air to be
supplied to the compressor to lower the temperature of the air to
be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, the injection
unit having a water supply system, an air supply system and a spray
nozzle for being supplied with water from the water supply system
and spraying water droplets, and a controlling unit for controlling
the water supply quantity and air supply quantity as to increase a
ratio of water to air, supplied to the spray nozzle when a spray
quantity of water droplets is more, as compared with a small spray
quantity.
Thereby, it is possible to obtain water droplets of a prescribed
diameter while keeping the air quantity small (it is preferable
when the water quantity is relatively small). In a case where air
is taken from the compressor, it is possible to supply a larger
amount of air from the taken air to the combustor, and an operation
of high output or high efficiency can be carried out even if the
water droplet spray quantity changes.
A seventh invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged at an upstream side of the compressor and
constructed so that water droplets are sprayed into the air to be
supplied to the compressor to lower the temperature of the air to
be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, said
injection unit having a water supply system, an air supply system
and a spray nozzle for being supplied with water and air from the
water supply system and air supply system and spraying water
droplets, and a controlling unit for controlling the water supply
quantity and air supply quantity so as to increase and decrease the
water supply quantity according to an increase and a decrease of a
spray quantity of water droplets and maintain the air supply
quantity to be constant.
Thereby, it is possible to execute a high output operation by water
spray while keeping the soundness of the apparatus and devices,
with a simple control.
An eighth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, and characterized by comprising
an injection unit, arranged at an upstream side of the compressor
and constructed so that water droplets are sprayed into the air to
be supplied to the compressor to lower the temperature of the air
to be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, the injection
unit having a water supply system, an air supply system and a spray
nozzle for being supplied with water and air from the water supply
system and air supply system and spraying water droplets, and a
controlling unit for controlling the injection unit so as to start
supplying of air to the spray nozzle first and then start to
supplying of water to the spray nozzle, thereby to start spraying
of water droplets.
A ninth invention is a gas turbine, having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, and characterized by comprising
an injection unit, arranged at an upstream side of the compressor
and constructed so that water droplets are sprayed into the air to
be supplied to the compressor to lower the temperature of the air
to be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, the injection
unit having a water supply system, an air supply system and a spray
nozzle for being supplied with water and air from the water supply
system and air supply system and spraying water droplets, and a
controlling unit for controlling the injection unit so that the
water droplet spraying is stopped by decreasing a quantity of air
supplied to the spray nozzle first and then decreasing a quantity
of water supplied to the spray nozzle.
Thereby, it is possible to secure the soundness of the apparatus
and devices at a time of starting the water spray operation or at a
time of stopping the water spray operation, and it is possible to
provide a gas turbine which outputs a high output by the water
spray operation. Further, it is possible to suppress occurrence of
water droplets having an undesired diameter at the time of starting
and stopping.
A tenth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, and characterized by comprising
an injection unit, arranged at an upstream side of the compressor
and constructed so that water droplets are sprayed into the air to
be supplied to the compressor to lower the temperature of the air
to be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, and a
controlling unit for controlling the injection unit so as to first
issue a signal for stopping the water droplet spraying and then
issue an instruction to decrease the compressor inlet guide vane
opening on the basis of a gas turbine trip signal, during operation
of the injection unit.
Thereby, a high output can be obtained by the water spray
operation, and even if a gas turbine trip occurs during the water
spray operation, it is possible to provide a gas turbine of a high
safety which can effect a smooth trip, securing the soundness of
the apparatus and devices.
An eleventh invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
the compressor, and a controlling unit, having a plurality of air
temperature detectors arranged in the duct on a peripheral
direction, for controlling the injection unit so as to decrease a
quantity of water spray when a deviation in detected value reaches
to a prescribed value, during an operation of spraying water
droplets.
Further, it is possible to control the water spray quantity so as
to decrease when the a set temperature set by taking account of
icing and so on exceeds a prescribed value. When the water spray
quantity is decreased, it is possible to control so as to increase,
according to a detection value, a flow rate of water flowing in a
spray nozzle portion corresponding to a position in which a
detection value changes largely by a prescribed value form an
average value of the other detection values, or it is possible to
decrease the water spray quantity of the whole spray nozzles.
A twelfth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
the compressor, and a controlling unit for controlling the
injection unit so as to monitor a flow rate by weight of air
introduced into the compressor and decrease a quantity of water
spray when the flow rate reaches to a prescribed value, during
operation of spraying water droplets.
Thereby, since the change can be directly monitored, stall and
icing can be precisely suppressed, whereby a gas turbine which can
carry out a high output operation by water spray can be provided
while keeping the soundness of the apparatus and devices.
In a case where a device for measuring an air quantity at the
compressor inlet is provided and a water quantity is controlled
relative to the air quantity at the compressor inlet during the
water spray operation, any of the operations can be effected in one
of which one arbitrary constant value is set in advance as an
allowable variation range and the water quantity is decrease not to
exceed the allowable variation range, in the other of which water
supply is stopped when the water quantity exceeds the allowable
variation range. In a case of stopping of water supply, any methods
can be taken one of which is a method of stopping water supply by
an operation of the feed water stopping valve of the water supply
system when it exceeds the allowable variation range and other is a
method of stopping the water supply by stoping the feed water pump
of the water supply system.
Further, this control unit is preferable to be applied in the case
where such a water spray quantity is injected that some of the
quantity thereof has not been evaporated and remains as water
droplets in the intake duct and the quantity of the not-evaporated
liquid droplets are introduced into the compressor.
For example, the above-mentioned detection is executed at an
interval of several minutes (for example, 2 to 3 minutes), and it
is possible to judge after monitoring at the detection
interval.
Since an air quantity decreases as the atmospheric temperature
rises, in order to distinguish it from an decrease of the air
quantity due to stall, it is preferable to calculate an air
quantity change by detecting the air temperature.
Further, the air temperature is preferable to be detected at a
compressor inlet portion (for example, between a downstream side of
the injection unit and the compressor inlet).
It is possible to replace the detection of an inlet air flow rate
by detection of a compressor discharge pressure by providing a
detection device detecting a compressor discharge pressure on a
compressor discharge air flow passage.
Alternatively, it is possible to provide means for detecting a gas
turbine intake air temperature and a control unit controlling so as
to inject water spray when the air temperature becomes a constant
value or more. At this time, although a gas temperature at an
upstream side of the injection unit and a gas temperature at a
downstream side of the injection unit are considered as a gas
temperature to be detected for the control, any gas temperature can
be used. In a case where it is detected at the downstream side of
the injection unit, it is possible to detect the air temperature at
a plurality of points in the same plane in a flow direction. When
the air temperature lowers than a lower limit value, a water spray
injection quantity is limited according to the air temperature.
Otherwise, it is possible to stop the water supply.
Thereby, a stable operation of the gas turbine can be achieved
while avoiding an icing phenomenon on the compressor inlet guide
vanes.
Further, by providing means for detecting the temperature and
humidity of a gas turbine intake air and a calculator for
calculating a wet-bulb potential temperature from the humidity, or
providing means for detecting an air wet-bulb potential
temperature, it is possible to provide a control unit controlling
so as to inject water spray when the wet-bulb potential temperature
is a constant value or more. In this case, although a wet-bulb
potential temperature at a upstream side of the injection unit and
a wet-bulb potential temperature at a downstream side of the
injection unit are considered as a wet-bulb potential temperature
used for the control, any of which can be used. In a case where the
wet-bulb potential temperature lowers than a lower limit value, the
water spray injection quantity can be limited according to the
temperature or it is possible to stop the water supply.
Thereby, a stable operation of the gas turbine can be achieved
while avoiding an icing phenomenon on the compressor inlet guide
vanes.
A thirteenth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
the compressor, a detection unit for detecting the pressure of a
casing wall of an inlet guide vane portion of the compressor, and a
controlling unit for controlling a quantity of water spray on the
basis of the detected wall pressure, during an operation of water
droplet injection.
For example, the above-mentioned control unit monitors the casing
wall pressure at a compressor inlet guide vane inlet and controls
so as to decrease the water spray quantity when the flow rate
becomes a prescribed value or more, during the water spray
operation.
Thereby, it is possible to monitor the casing pressure of the
compressor inlet guide vane inlet and approximate an air flow rate
change thereby, whereby it is possible to easily detect a condition
change, and make the output high by the water spray injection while
easily securing the soundness of the apparatus and devices.
Further, other than it, it is possible to detect the pressure
inside the compressor and control so as to decrease the water
injection quantity on the basis of rising in the pressure more than
a prescribed value. Thereby, the detecting device is easily
installed and the air quantity can be easily detected.
Further, it is possible to detect a change in pressure inside the
compressor and to control so as to decrease the water spray
quantity when the pressure change becomes larger than a prescribed
value. Whereby, it is possible to directly measure an abnormal
condition and detect precisely the event.
A fourteenth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
the compressor, and a controlling unit for controlling the
injection unit so as to monitor a discharge pressure of the
compressor and decrease a quantity of water spray when the
discharge pressure becomes less a prescribed value, during an
operation of spraying water droplets.
For example, the above-mentioned control unit monitors a compressor
discharge pressure and control so as to the water spray quantity
when the discharge pressure becomes less than a prescribed value,
during a water spray injection operation. Thereby, it is possible
to rapidly detect an abnormal condition which is high in pressure
level, such as icing, stall, etc. Therefore, it is possible to
effect a high output operation by the water spray injection and
detect early occurrence of icing, stall, etc. and maintain the
soundness of the apparatus and devices.
When a means for detecting a compressor discharge pressure is
provided and a water injection quantity is controlled according to
the compressor discharge pressure during the water spray injection
operation, a constant value is set in advance as an allowable
variation range and it is possible to operate so as to decrease not
to exceed the allowable variation range or to operate so as to stop
the water supply when it exceed the allowable variation range.
A fifteenth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
the compressor, and a controlling unit for monitoring an adiabatic
efficiency of the compressor and controlling a quantity of water
spray on the basis of the adiabatic efficiency, during an operation
of water droplet injection.
For example, the above-mentioned control unit monitors a compressor
adiabatic efficiency and controls so as to decrease the water spray
quantity when the adiabatic efficiency lowers less than a
prescribed value, during the water spray injection operation.
Thereby, even if an atmospheric temperature changes, the
temperature can be detected, and an icing, stall, etc. can be
detected. Therefore, even if the atmospheric temperature changes,
it is possible to easily protect the apparatus and devices from the
icing, stall, etc. and to provide a gas turbine of high output by
the water spray injection. Further, mismatching between stages
inside the compressor can be detected, a further safe operation can
be effected.
When a means for measuring a compressor adiabatic efficiency is
provided and a water quantity is controlled according to the
compressor adiabatic efficiency during the water spray injection
operation, a constant value is set in advance as an allowable
variation range, and any of an operation in which the water
quantity is decreased not to exceed the allowable variation range
and an operation in which the water supply is stopped when it
exceeds the allowable variation range can be practiced.
A sixteenth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
said compressor, and a controlling unit for monitoring an exhaust
gas temperature and controlling a quantity of water spray on the
basis of the exhaust gas temperature, during an operation of water
droplet injection.
For example, the above-mentioned control unit monitors an exhaust
gas temperature and control so as to decrease the spray water
quantity when the exhaust gas temperature becomes a prescribed
value or more, during the water spray injection operation.
Thereby, it is possible to rapidly detect a change in event and
suitably protect the apparatus and devices from an abnormal
condition, and achieve a high output operation of the gas turbine
by the water spray injection.
By providing a means for detecting a combustion exhaust gas
temperature, when the water quantity is controlled according to the
combustion exhaust gas temperature during the water spray injection
operation, a constant value is set in advance as an allowable
variation range and any of an operation in which the water quantity
is decreased not to exceed the allowable variation range and an
operation in which the water supply is stopped when it exceeds the
allowable variation range, can be effected.
A seventeenth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
the compressor, and a controlling unit for monitoring vibrations of
a gas turbine bearing and controlling a quantity of water spray on
the basis of the vibration value, during an operation of water
droplet injection.
For example, the above-mentioned control unit monitors vibrations
of a gas turbine bearing and controls so as to decrease the water
spray quantity when the vibrations exceeds a prescribed value,
during the water spray injection operation.
Thereby, it can be directly detected that stool occurs partially in
a peripheral direction, and partial stall and icing can be directly
detected. It is possible to protect the apparatus and devices from
abnormality by detection of partial stall and icing, and provide a
high output operation of gas turbine by the water spray injection.
Further, it is possible to detect suitably vibrations due to
unbalance of a gas turbine rotating portion, caused by ununiformity
in water droplets introduced in the compressor and carry out a high
safety operation.
In a case where by providing a means for detecting vibrations of
the gas turbine bearing, and the water injection quantity is
controlled according to the vibrations of the bearing during the
water spray injection operation, a constant value is set in advance
as an allowable variation range, it is possible to effect an
operation that the water quantity is decreased not to exceed the
allowable variation range or an operation that the water supply is
stopped when it exceeds the allowable variation range.
An eighteenth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
the compressor, and a controlling unit for monitoring a thrust
bearing metal temperature of the gas turbine and controlling a
quantity of water spray injection on the basis of the thrust
bearing metal temperature, during an operation of water droplet
injection.
For example, the above-mentioned control unit monitors a metal
temperature of a gas turbine thrust bearing and controls so as to
decrease the water spray quantity when the metal temperature
exceeds a prescribed value, during the water spray injection
operation.
Thereby, a temperature change in the thrust bearing can be detected
and if an unbalance in the thrust bearing occurs, it can be surely
detected. It is possible to protect the apparatus and devices from
abnormality caused by the unbalance, and provide a high output
operation of gas turbine by the water spray injection.
In a case where by providing a means for detecting a metal
temperature of the gas turbine thrust bearing, and the water
quantity is controlled according to the metal temperature of the
thrust bearing during the water spray injection operation, a
constant value is set in advance as an allowable variation range,
it is possible to effect an operation that the water quantity is
decreased not to exceed the allowable variation range or an
operation that the water supply is stopped when it exceeds the
allowable variation range.
A nineteenth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
the compressor, and a controlling unit for monitoring an axial flow
velocity of fluid flowing in the compressor and controlling a
quantity of water spray on the basis of the axial flow velocity,
during an operation of water droplet injection.
For example, the above-mentioned control unit monitors an axial
flow velocity of fluid inside the compressor and controls so as to
decrease the water spray quantity when the axial flow velocity
lowered to a prescribed value or less, during the water spray
injection operation. Since it is determined irrespective of such
conditions as atmospheric temperature, etc., the control can be
easily carried out and a precise control can be effected with
respect to this point. Further, it is possible to determine a limit
value of a water spray quantity on the basis of this value and make
it a control ground, whereby direct control can be effected.
Thereby, it is possible to protect the apparatus and devices from
abnormality caused by an icing and so on and provide a high output
operation of gas turbine by the water spray injection.
In a case where by providing a means for calculating an axial flow
velocity inside the compressor, and the water quantity is
controlled according to the axial flow velocity of fluid in the
compressor during the water spray injection operation, although the
axial flow velocity can be considered to be calculated at any
stage, it is possible to calculate an axial flow velocity at the
final stage of the compressor from an air quantity at the
compressor inlet, a compressor discharge pressure and a compressor
discharge temperature. An operation method in which a constant
value is set in advance as an allowable variation range, and the
water quantity is decreased not to exceed the allowable variation
range and an operation that the water supply injection is stopped
when it exceeds the allowable variation range are considered,
however, any of the operations can be used. Further, When the water
supply is stopped, although there are a method of stopping water
supply by an operation of feed water shut-off valve of a feed water
system and a method of stopping water supply by stopping a feed
water pump, any of the methods can be used.
Alternatively, it is possible to provide a means for detecting a
drain quantity in the compressor inlet air intake portion and a
control unit controlling the water quantity according to the drain
quantity. An operation method in which an arbitrary constant value
is set in advance as an allowable variation range, and the water
quantity is decreased not to exceed the allowable variation range
and an operation method in which the water supply is stopped when
it exceeds the allowable variation range are considered, however,
any of the operation methods can be used. The drain quantity can be
detected by arranging a high level switch in the drain tank.
When the water supply is stopped, although there are a method of
stopping water supply by an operation of feed water shut-off valve
of a feed water system and a method and an operation method of
stopping water supply by stopping the feed water pump of the feed
water system, any of the methods can be used.
Thereby, since the compressor is made not to suck water droplets of
large diameter, it is possible to carry out a stable operation of
the compressor and gas turbine and to avoid wear of the compressor
blades.
A twentieth invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
said compressor, and a controlling unit for controlling said
injection unit so as to increase a quantity of fuel supplied to the
combustor at time of water droplet spraying, as compared with a
quantity of fuel supplied to the combustor at time of stopping
water droplet spraying.
Further, it is preferable to have a control unit controlling so as
to increase a fuel supply quantity supplied to the combustor more
than before the water spray injection starting on the basis of the
water spray injection starting and decrease the fuel supply
quantity less than before the water spray injection stopping on the
basis of the water spray injection stopping.
Further, at the time of water spray injection also, it is
preferable to provide a control unit controlling so as to increase
a fuel injection amount to the combustor more when the water
droplet spray injection quantity is more, than when the water spray
injection quantity is small.
Further, it is preferable to control (correct or compensate) the
fuel supply quantity according to the humidity.
In a case where a gas turbine exhaust gas temperature is used to
control a gas turbine inlet temperature constant, a method of
correcting a value detected of the gas turbine exhaust gas
temperature according to the humidity quantity at the gas turbine
inlet and a method of correcting a predetermined exhaust gas
temperature control line according to the humidity quantity at the
gas turbine inlet are considered.
Concretely, for example, it is possible to increase a fuel
injection amount by correcting the exhaust gas temperature control
line set based on water droplet spray not practiced toward a high
temperature side during the water spray injection operation.
Alternatively, it is possible to increase the fuel injection amount
by correcting a measure value of exhaust gas temperature.
In a case where detection of the humidity around the compressor is
practiced at an upstream side of the compressor, a method of
calculating it from the humidity of gas at the upstream side of the
injection unit, water spray injection quantity from the injection
unit and a drain amount occurred in the intake air duct can be
considered. The detection of humidity can be practiced at the
compressor discharge portion.
Thereby, an operation of the gas turbine that always keep the
combustion temperature constant without influence of the water
spray injection is possible and it is possible to achieve an output
improving effect by water spray injection to the maximum.
Thereby, the combustion temperature is suitably corrected (for
example, corrected to a higher temperature side) and a further
improvement on output can be achieved during the water spray
injection operation.
A twenty-first invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising an
injection unit, arranged within an intake air duct at an upstream
side of the compressor and constructed so that water droplets are
sprayed into the air to be supplied to the compressor to lower the
temperature of the air to be supplied into the compressor to a
temperature lower than an atmospheric temperature and the sprayed
water droplets introduced into the compressor with the air having
been lowered in temperature are evaporated during passage through
the compressor, a detection unit for detecting NOx concentration in
the exhaust gas, and a controlling unit for controlling a quantity
of water spray on the basis of the detected NOx concentration.
As compared with NOx countermeasures by water or steam spraying
into the combustor, a mixing condition of water and air is better
because a gas that air and water in the combustor are mixed
homogeneously flows in the combustor. Therefore, it is possible
realize a low NOx emission while suppressing combustion vibrations
and effecting stable combustion, with a simple apparatus.
Based on a value detected of NOx concentration of gas turbine
exhaust gas, a water quantity is controlled according to difference
between a target NOx concentration and the above-mentioned gas
turbine exhaust gas NOx concentration value, whereby it is possible
to decrease the NOx concentration to the target value.
A twenty-second invention is a gas turbine having a compressor for
compressing an air supplied therein and discharging a compressed
air, a combustor for combusting the compressed gas from the
compressor and a fuel and a gas turbine to be driven by a
combustion gas from the combustor, characterized by comprising a
premixer provided in the combustor for burning premixed gas formed
by premixing fuel and air an injection unit, arranged within an
intake air duct at an upstream side of the compressor and
constructed so that water droplets are sprayed into the air to be
supplied to the compressor to lower the temperature of the air to
be supplied into the compressor to a temperature lower than an
atmospheric temperature and the sprayed water droplets introduced
into the compressor with the air having been lowered in temperature
are evaporated during passage through the compressor, and a
controlling unit for monitoring an adiabatic efficiency of the
compressor and controlling a quantity of water spray on the basis
of the adiabatic efficiency, during an operation of water droplet
injection.
Further, it is preferable to control so that a ratio of fuel to air
in a premixed gas becomes higher when the water spray quantity is
more.
A variation in water spray quantities changes greatly a condition
of fluid. However, it is possible to suppress the combustion
condition becoming unstable during the water spray injection
operation by the invention. Therefore, it is possible to provide a
gas turbine which has a high stability of combustion and is able to
carry out a high output operation by water spray injection.
Further, in stead of the above-mentioned control unit, it is
possible to provide a NOx concentration detection device for
detecting a NOx concentration of the combustion exhaust gas, a
pressure variation detection device for detecting pressure
variation inside the combustor, and a control unit controlling so
as to increase the above-mentioned water droplet spray quantity
when the NOx concentration reaches to a prescribed value or more,
and decrease the water droplet spray quantity when the pressure
variation becomes a prescribed value or more.
Thereby, an operation that an output is made higher by the water
spray injection, an emitted NOx concentration is to lower and a
combustion stability is higher.
Further, by providing a means for detecting the NOx concentration
of gas turbine exhaust gas and the pressure variation in the
combustor, it is possible to control the water spray quantity at
the upstream side of the compressor so as to suppress the gas
turbine exhaust gas NOx concentration and the pressure variation in
the combustor within allowable values.
Further, in a case where steam or water is injected into the
combustor, also, in the similar manner, it is possible to control
the water injection quantity at the upstream side of the compressor
and the water or steam injection quantity to the combustor so that
the gas turbine exhaust gas NOx concentration and the combustor
inside pressure variation during an operation of the water spray
injection at the upstream side of the compressor each become within
an allowable value. Thereby, it is possible to achieve a stable
operation of the combustor.
Further, by providing a means for monitoring the gas turbine
exhaust gas NOx concentration and the combustor inside pressure
variation, it is possible to control a premixed combustion ratio so
that the gas turbine exhaust gas NOx concentration and the
combustor inside pressure variation each do not exceed a constant
value set in advance during the water spray injection operation.
Thereby, it is possible to achieve a stable operation of the
combustor.
With respect to the gas turbine explained above, it is possible to
make higher output of gas turbines already made and installed in
addition to gas turbines newly installed. In this case, the already
made gas turbines each are provided with the above-mentioned
injection unit, any of the above-mentioned control units according
to an object or demand, related apparatus and devices if necessary,
as a gas turbine output augmenting system.
In this manner, the above-mentioned operation of each of the
inventions can be achieved by providing the above-mentioned
injection unit, control unit, or, further necessary related
apparatus and devices even in already made gas turbines.
Further, if it is accepted that there may be some cases wherein the
above-mentioned operation and effect are not sufficiently
presented, instead of the above-mentioned injection unit, arranged
within an intake air duct at an upstream side of the compressor and
constructed so that water droplets are injected into the air to be
supplied to the compressor to lower the temperature of the air to
be supplied into the compressor than an atmospheric temperature and
the sprayed water droplets introduced into the compressor with the
air having lowered in temperature are evaporated during passage
through the compressor, or in addition to the above-mentioned
injection unit, the above-mentioned control unit can be employed
for a system or apparatus provided with a cooling device for
cooling air supplied to the compressor to increase output. The
cooling device can be a device for effecting direct or indirect
heat exchange with air supplied to the injection unit and the
compressor, using a cold heat source such as ice, liquid air,
etc.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic block diagram of a gas turbine of an
embodiment of the invention;
FIG. 2A is a diagram indicating gas turbine output characteristics
versus atmospheric temperatures;
FIG. 2B is a diagram indicating water injection quantities versus
atmospheric temperatures;
FIG. 3 is a diagram indicating allowable water injection quantities
relative to atmospheric temperatures and angles of compressor inlet
guide vanes (IGV);
FIG. 4 is a diagram indicating allowable water injection quantities
relative to atmospheric temperatures and relative humidities;
FIG. 5A is a diagram indicating a limit value for quantities of
water droplets to be introduced into the compressor;
FIG. 5B is a diagram indicating operation status along a wet air
curve;
FIG. 6 is a schematic block diagram of a gas turbine of another
embodiment of the invention;
FIG. 7 is a block diagram indicating the control contents of an
embodiment of the invention;
FIG. 8 is a diagram indicating relationship of water injection
quantities with particle diameter and air quantities when a air
water ratio is constant;
FIG. 9 is a schematic block diagram of a gas turbine of another
embodiment of the invention;
FIG. 10 is a diagram indicating relationships of water spray
quantities with auxiliary header water supply quantities;
FIG. 11A is a diagram indicating relationships of water spray
quantities with air water ratios and air quantities when the
particle diameter is constant;
FIG. 11B is a diagram indicating relationships of water spray
quantities with particle diameter and air water ratios when air
quantity is constant;
FIG. 12A is a schematic block diagram of a gas turbine of another
embodiment of the invention;
FIG. 12B is a section taken along a line B--B of FIG. 12A;
FIG. 13 is a diagram indicating water injection limits relative to
compressor inlet temperatures when atmospheric temperature is
low;
FIG. 14 is a schematic block diagram of a gas turbine of another
embodiment of the invention;
FIG. 15 is a diagram indicating operational status of the gas
turbine under occurrence of icing phenomena in the inlet of the
compressor;
FIG. 16 is a diagram indicating operational status of the gas
turbine under occurrence of stall phenomena within the
compressor;
FIG. 17A is a diagram indicating a change in velocity triangles of
a compressor rotor blade due to injection of water droplets into
the compressor;
FIG. 17B is a diagram indicating a change in incident angles of the
compressor rotor blade with respect to a quantity of water droplets
to be injected into the compressor;
FIG. 18 is a block diagram indicating a method for calculating an
axial velocity at the final stage of the compressor for the purpose
of water quantity limitation;
FIG. 19 is a schematic control block diagram indicating a control
controlling fuel injection quantities into a combustor;
FIG. 20 is a schematic control block diagram indicating a control
controlling fuel injection quantities into a combustor;
FIG. 21A is a diagrams indicating relationships of gas turbine
exhaust gas NOx concentrations and water injection quantities in
the compressor inlet;
FIG. 21B is a diagrams indicating relationships of combustion
vibrations and water injection quantities in the compressor
inlet;
FIG. 22A is a diagrams indicating a relationship of gas turbine
exhaust gas NOx concentrations and premixture combustion ratios in
the combustor; and
FIG. 22A is a diagrams indicating a relationship of combustion
vibrations and premixture combustion ratios in the combustor.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
A first embodiment of the invention will be described with
reference to FIGS. 1 and 2A and 2B.
A gas turbine according to this embodiment of the invention as
indicated in FIG. 1 comprises a compressor 1 which compresses and
discharges a gas, a combustor 2 to which the gas compressed by the
compressor is supplied, a turbine 3 which is driven by a combustion
gas of the combustor 2, and a generator 4 which is connected to the
shaft of the turbine 3. A gas turbine exhaust gas is introduced
into an exhaust heat recovery boiler 72 for heat exchange with a
steam or water which becomes a working medium to drive a steam
turbine 73, then it is discharged to the atmosphere. The steam
turbine 73 which is driven by the steam which is heated through the
heat exchange with the gas turbine exhaust gas is directly coupled
with the generator 4. A steam discharged from the steam turbine 73
is cooled by a condenser 74 to be condensed into water. An air
suction chamber 11 takes in air to be supplied to the compressor 1.
Further, a louver 10 is normally provided in the upstream side of
the suction chamber 11. The louver 10 is provided with an air
filter which is installed on the side of the compressor (in the
downstream side). Since the air filter is provided immediately
downstream of louver 10, its illustration is omitted. An intake
duct 13 is connected to the suction chamber 11 at the downstream
side thereof, and a silencer 12 is installed within the intake
duct. Further, within the intake duct 13, spray water piping 15,
atomizing air piping 16 and a spray nozzle or nozzles 17 are
provided in the downstream side of the silencer 12. The intake duct
13 is connected to a compressor intake portion 14 for introducing
air into the compressor 1. Further, the spray water piping 15 and
the atomizing air piping 16 are arranged as a plurality of systems.
In FIG. 1, a single system is illustrated.
Spray water is supplied from a feed water tank 18 to a feed water
header 25 via a foreign matter removal strainer 19, a feed water
pump 20, a feed water shut-off valve 21, a feed water supply
regulating valve 22, a water flowmeter 23, and a foreign matter
removal filter 24. Water is supplied from the feed water header 25
to the spray water piping 15 via a feed water header outlet flow
regulating valve 26.
In a case where two-fluid spray nozzles are used, a water droplet
atomizing air system becomes necessary. As a water droplet
atomizing air, an air extracted from the compressor is supplied to
a spray air header 32 via an air shut-off valve 27, an air pressure
regulating valve 28, a foreign matter removing cyclone separator
29, an air flow meter 30 and an air flow regulating valve 31. Air
is supplied from spray air header 32 to each spray air piping 16
disposed within intake duct 13.
In FIG. 1, air is indicated to be extracted from the discharge
portion of compressor 1, however, it may be extracted from an
intermediate stage of the compressor.
Signals of a feed water quantity and a spray air quantity measured
by the water flow meter 23 the and air flow meter 30 are
transmitted to a control unit 35. The control unit 35 computes a
required water quantity and air quantity from operating conditions
of the gas turbine itself, and controls the feed water flow
regulating valve 22 and the air flow regulating valve 31. Further,
through computation by comparing with the operation limits of the
gas turbine itself, the control unit sends open/close operation
signals to the feed water pump 20 and the feed water shut-off valve
21.
Gas turbine output augmentation according to water spray injection
quantities will be explained hereunder.
Water droplets sprayed or injected from the water spray nozzle 17
each are about 10 .mu.m by Sautor average particle diameter
(S.M.D.). Water droplets sprayed from the water spray nozzle 17 are
partly vaporized during flowing down within the intake duct 13
until they enter the compressor 1. The water droplets are mixed
with air introduced from the suction chamber 11. Suction air
including sprayed water droplets is introduced into the compressor
1 and the introduced water droplets evaporate during flowing within
the compressor 1. Then, compressed air discharged from the
compressor 1 and fuel are supplied to the combustor 2 and burn.
Combustion gas is supplied to the gas turbine 3 and drives it. The
turbine exhaust gas is introduced into the exhaust heat recovery
boiler 72 as a heat source, and steam generated there drives the
steam turbine 73. Detailed explanation will be given hereunder.
By introducing liquid droplets to be evaporated within the
compressor 1 in which the above-mentioned mixing gas flows and by
evaporation of the water droplets, it is possible to further
improve an efficiency under a partial load than in the
above-mentioned prior arts. When the water droplets entered into
the inside of the compressor evaporate and the vaporization is
completed within the compressor 1, the gas within the compressor 1
is subjected further to an adiabatic compression. At that time, a
specific heat at constant pressure of water vapor has a value of
approximately two-fold of that of air in the vicinity of a typical
temperature (300.degree. C.) within the compressor, therefore,
there is such an advantage that, in terms of thermal capacity
conversion of the vapor to air, its operating fluid is assumed to
increase by an addition of air which is equivalent to twice the
weight of water droplets to have been vaporized. That is, there is
an effect to lower an outlet mixed gas (air and vapor) temperature
of the compressor, or a temperature rise suppression effect. By
vaporization of water droplets within the compressor as described
above, a discharged mixed gas temperature at the outlet of the
compressor is caused to drop. Since a power of the compressor is
equal to a difference in enthalpies of mixed gas between inlet and
outlet of the compressor, and since enthalpy of mixed gas is
proportional to temperatures, when its outlet mixed gas temperature
of the compressed is decreased, the power of the compressor can be
reduced and an efficiency can be improved.
Assuming that a compressor inlet suction temperature is T1; a
compressor outlet temperature, T2; a combustion temperature, T3;
and a gas turbine outlet temperature, T4, a gas turbine efficiency
.eta. can be approximated by the following equation:
Since the second term on the righthand side of equation becomes
small when the compressor inlet temperature T2 lowers to T2'
(<T2) by mixing and evaporation of the sprayed water, it is
understood that the efficiency improves by water injection. In
other words, a heat energy Cp (T4-T1) to be discharged outside a
thermal engine of gas turbine does not change substantially before
and after the application of the invention, however, an input fuel
energy Cp (T3-T2') is caused to increase by Cp (T2-T2'), i.e.,
corresponding to a portion of drop in the compressor's work. On the
other hand, as described above, since the portion of drop in the
compressor's work is equivalent to the augmented output, all of
this fuel incremental portion substantially contributes to an
augmentation of output of the gas turbine. That is, an augmented
output portion has a thermal efficiency of 100%. Therefore, the gas
turbine's thermal efficiency can be improved. Since, the combustion
temperature is kept constant, an efficiency of bottoming cycle is
equal to that before application of the present invention, so that
a total thermal efficiency of the combined cycle can be
improved.
Further, when the particle size of the spray liquid droplets is
large, the droplets impinge on blades and casing of the compressor
1 and receive heat from the metal to evaporate, so that an effect
of reducing the temperature of working fluid may be prevented.
Therefore, from this point of view, the liquid particle size is
preferable to be small. The spray liquid droplets have a
distribution of particle size. From the point of view of
suppressing impingement on the blades and casing of the compressor
1 and preventing the blades from erosion, main sprayed liquid size
is made into a diameter of 50 .mu.m or less. From a point of view
of making less an influence of action on the blades, it is
preferable to be a maximum particle diameter of 50 .mu.m or
less.
Further, liquid particles of finer particle size can re distributed
uniformly in intake air and suppress occurrence of a temperature
distribution within the compressor 1. From this point of view, the
particle diameter is preferable to be 30 .mu.m or less by Sautor
average particle diameter (S.D.M.). Since liquid droplets jetted
from the spray nozzle have a distribution of particle size, it is
not easy to measure the particle size by maximum diameter.
Therefore, practically, the size measured by the above-mentioned
S.D.M. is used. The particle size is preferable to be small,
however, since a high precision manufacturing technique is required
for the spray nozzle making fine liquid droplets, a lower limit
that the particle size can be minimized technically is a practical
range of the particle size. Therefore, for example, a lower limit
in the above-mentioned main particle size, the maximum particle
size or the average particle size is 1 .mu.m. Further, the finer
the particle size is made, the larger the energy for making
particles of such sizes becomes, so that the lower limit can be
determined considering the energy used for production of fine
particles. Water droplets of such a size that they float in the air
and are difficult to drop have a good condition of contact surface
in general.
Air passes through the compressor 1 for a small time, and from the
point of view that liquid droplets are caused to be well evaporated
for this time and an evaporation efficiency is raised thereby,
S.D.M. is preferable to be 30 .mu.m or less.
Further, since a spray nozzle for making small diameter liquid
droplets requires a manufacturing technique of high precision, a
limit that the droplets can be made small becomes a lower limit of
the particle size or diameter. For example, it is 1 .mu.m.
When the size of liquid droplets is too large, it is difficult for
the liquid droplets to be evaporated well in the compressor 1.
The quantity of introduced liquid particles can be adjusted
according to a temperature, a humidity or an extent of output
augmentation as described later. For example, 0.2 wt % or more of a
suction air flow rate by weight can be introduced, taking into
consideration an evaporation quantity of sprayed water droplets
evaporating during flow from a spraying position to the compressor
inlet. An upper limit of introduced water droplets is determined
from a point of view of maintaining well the function of the
compressor as described later. For example, the upper limit is
determined to be 5 wt % and an introduction range of quantity of
water droplets can be determined to be that value or less.
In the intake duct 13, a quantity of air taken in the gas turbine
is increased by cooling the intake air and making the density of
the air higher. Inside the compressor 1, compressed air is cooled
and the power for the compressor 1 is decreased. Further, a working
fluid for the turbine increases by evaporating water droplets
within the compressor 1.
Therefore, since the power for the compressor 1 can be decreased
while increasing a turbine shaft output, a high output in the
turbine can be obtained. Further, it can contribute to an
improvement of the efficiency.
When a water spray quantity from the spray nozzle 17 is increasing,
at first (as a first stage) a compressor inlet air quantity
increases as a compressor inlet temperature lowers, whereby an
output increases. When a water spray quantity is being increased
further, as a second stage, an increasing rate of an output
augmentation ratio changes, the power for the compressor decreases
due to lowering of a compressor inside temperature, and the output
has a tendency to increase by an increase of a gas turbine working
fluid due to evaporation of water droplets.
This output augmenting method of the invention can be applied not
only to the combined cycle of the gas turbine and the steam turbine
as indicated in FIG. 1, but also to a power plant having a single
gas turbine.
Further, the sprayed water is not limited to pure water, and any
mixture solution with anti-freezing solution or alcohol such as
methanol, when the atmospheric temperature is low, or with other
materials may be used.
When a gas turbine output is increased by water spray, a water
spray quantity is within a range in which evaporation of the
injected water droplets is completed at an upstream side of the
compressor, and water droplets are not introduced inside the
compressor 1, whereby output augmentation can be effected only by
lowering of the compressor inlet temperature. In this case, only an
output increase until the above-mentioned first stage can be
obtained. When the atmospheric temperature is low or the
atmospheric humidity is high, since an evaporation quantity of
water droplets within the intake duct at the upstream side of the
compressor is small, an output augmentation amount is small,
however, a gas flow in the compressor is not deviated from a design
flow condition and a stable operation of the compressor can be
carried out.
Further, when an output of the gas turbine is increased by water
spray, a spray nozzle 17 is provided at an inlet of the compressor
1 as in the compressor intake portion 14, in the downstream side of
the intake duct 13, almost all quantity of the sprayed water is
introduced in the compressor 1 at a condition of water droplets,
and the water droplets are evaporated during flowing within the
compressor, whereby the heat of ambient air is absorbed, the
temperature within the compressor is lowered and the power for the
compressor is decreased. The output augmentation also can be
carried out thereby. In this case, an output augmentation amount is
smaller by such an amount that an output increase can be obtained
by lowering the compressor inlet temperature, and the output
increase can be achieved by an action of water droplets within the
compressor. In this method, a control is simple because the water
spray conditions are not related to the atmospheric humidity, and
the number of the spray nozzles can be reduced because the water
droplet size can be relatively large. Therefore, this can be
achieved by the most simple equipment as a gas turbine output
augmenting mechanism by water spray.
In this time, as indicated by line A in FIG. 2A, under normal
operation without application of water spray, outputs of the gas
turbine decline as shown by a line A in FIG. 2A since the air
quantity at the inlet of the compressor which is the working medium
decreases with an increase of the atmospheric temperature. Here, in
order to recover the drop of the gas turbine's output, when water
is sprayed in the upstream side of the compressor 1, a resultant
gas turbine output increases with respect to a same atmospheric
temperature as indicated by line B in FIG. 2A. As a method of water
injection, by predetermining line B, until an output of the
generator 4 arrives at an output value required for a given
atmospheric temperature, the control unit 35 sends an open
operation signal to the feed water flow regulating valve 22 to
increase its water spray quantity. At the same time, in order to
maintain atomized particle sizes constantly, the control unit also
sends an open operation signal to air flow regulating valve 31 in
proportion to an increases water Quantity to increase the injection
air.
Alternatively, as indicated in FIG. 2B, by determining an injection
planned quantity line having a predetermined margin with respect to
a water droplet limit quantity line which has been set relative to
atmospheric temperatures and humidities, water is sprayed
corresponding to the injection planned quantity. In this case where
a water droplet spray limit quantity (limit line) and a planned
injection quantity are indicated, a gas turbine output has an
augmentation value corresponding to the atmospheric temperature and
humidity during operation and the injection water quantity.
Also, output characteristics of FIG. 2A and quantities of water
injection (water spray) of FIG. 2B may be set with respect to the
inlet temperatures of the compressor. In the case they are set up
with respect to the atmospheric temperature, the temperature
detector 38 and humidity detector 75 provided in the upper stream
of the water injection unit as indicated in FIG. 1 will be used. In
the case they are set up with respect to the inlet temperature of
the compressor, the temperature detector 36 and humidity detector
61 which are provided between the down stream of the water
injection unit and the upper stream of the compressor are used. In
order to improve precision of measurements, detection at a
plurality of points may be made.
Further, in shift to a normal operation (for example, a rated
operation) of the gas turbine from starting by raising the r.p.m.
of the gas turbine and increasing a turbine load from a partial
load operation, an output augmentation by water spray at the
upstream side of the compressor 1 is carried out by stopping the
water spray injection in a time from the starting to the load
raising, and starting the water spray after shifting to the normal
operation.
For example, water spray from the water spray nozzle 17 is stopped
during the time from starting of the gas turbine to a partial load
operation, and the water spray is practiced by detecting the
condition that the gas turbine reaches an operation of a constant
combustion temperature under the conditions that the compressor
inlet guide vanes are fully opened and the combustion temperature
becomes maximum.
Alternatively, the water spray is stopped by detecting the
compressor inlet guide vane opening until the inlet guide vanes
reach to an opening at a normal operation from starting, and the
water spray from the spray nozzle 17 is started when the inlet
guide vanes reach the opening at the normal operation. Thereby,
misfire at the time of starting is prevented and the starting of
high stability is carried out. Further, a starting time of the gas
turbine in which a water spray operation is carried out can be
shortened.
Otherwise, in a case where in a gas turbine which comprises a
compressor 1, a combustor 2 and a turbine 3, and is provided with a
spray nozzle 17 for water spray injection as mentioned above, the
above-mentioned combustor 2 has a pilot burner for diffusion
combustion of fuel and a main burner for premixed combustion of a
premixture of fuel and an oxidizer such as air, after the gas
turbine has reached a rated r.p.m. at the time of starting, water
spray injection is started at a predetermined quantity by the spray
nozzle 17 before a load is output, and it is possible to effect a
combustor operation by the pilot burner and then start a load
operation by the main burner. And it may be possible to increase to
a rated load. Further, in a case where a plurality of main burners
are provided, it is preferable to conduct the water spray injection
even at the switching time at which the number of the burners used
is increased, or the like.
By controlling the spray nozzle 17 in this manner, even in the gas
turbine which is designed to be low in NOx concentration during
normal operation, it is possible to suppress occurrence of NOx at
the switching time from the pilot burner by which NOx may occur
temporarily at the stating time to the main burner. Therefore, it
is possible to execute low NOx combustion. Additionally, since the
water spray injection is started before a load is output, it is
possible to stably and smoothly increase the load.
Alternatively, it is possible that the water spray injection is
started at a predetermined quantity by the spray nozzle 17 after an
operation by the pilot burner starts to output a load, and then it
is shifted to a load operation to output a load by igniting the
main burner, and so on. Thereby, even with a gas turbine which is
designed to be low in NOx concentration during normal operation, it
is possible to suppress occurrence of NOx at the switching time
from the pilot burner by which NOx may occur temporarily at the
starting time to the main burner. Therefore, it is possible to
execute a low NOx operation even at the time of starting.
Additionally, since the water spray is injected before using the
main burner after starting to output a load by the pilot burner, it
is possible to surely generate pilot flame and increase a load.
Further, it is preferable for the spray nozzle 17 to provide a Si
strainer or Ca strainer for capturing Si or its compounds, or Ca or
its compound in feed water in the spray water piping 15. It is more
preferable to provide a strainer for capturing Si and Ca and their
compounds. It also is possible to remove foreign matter in the
make-up feed water tank 18, and to construct the above-mentioned
foreign matter removing filter 24 to be the above-mentioned
strainer for the Si, Ca, etc. Thereby, it is possible to suppress a
decrease in efficiency of the gas turbine according to time
passage, which decrease is caused by introduction of water droplets
into the compressor, which droplets include fine Si, Ca, etc.
included in feed water and are injected from the spray nozzle 17,
and by adhesion and accumulation of Si, Ca, etc. on the compressor
blades, etc. The provision of the strainer can contribute to
maintaining of the efficiency of gas turbine.
Alternatively, feed water is caused to be supplied to the spray
nozzle 17 through a desalting apparatus and the Si strainer or Ca
strainer. For example, it is preferable to cause feed water to be
supplied to the spray nozzle 17 after purifying the feed water in
the desalting apparatus, and then further purifying it in the Si
strainer or the Ca strainer. The desalting apparatus removes Na,
etc. in the feed water, and the strainer captures and removes Si,
etc. which is difficult to dissolve in the water.
For example, it is considered to provide the Si strainer and/or the
Ca strainer with a filter of mesh which captures Si or its
compounds of 1 .mu.m or larger and causes Si, its compounds of
smaller than 1 .mu.m to pass through. Taking account of a stable
operation of the gas turbine for a long time, it is more preferable
to provide a filter of mesh capturing of Si, its compounds of 0.3
.mu.m or larger and passing through of them smaller than the
size.
A second embodiment of the invention will be described with
reference to FIGS. 1 and 3.
In the second embodiment, a water spray quantity is controlled
according to an opening of inlet guide vanes of the compressor 1.
Concretely, a water spray quantity is made more when the compressor
inlet guide vane opening is larger than when small.
The present embodiment has basically the same construction as the
first embodiment. The second embodiment is provided with a control
unit in which signals of opening of the compressor inlet guide
vanes are inputted in the control unit 35 and a water spray
quantity is controlled according to the signals, in addition to the
construction of the first embodiment.
FIG. 3 shows planning lines for water injection (spray) quantities
controlled according to atmospheric temperatures, in which its
water spray quantity is controlled so as to differ according to
openings of the inlet guide vanes of the compressor.
In this embodiment, its water spray injection is executed when the
opening of its inlet guide vanes of the compressor is at an
intermediate opening, namely, under a partial loading condition.
According to a power demand from the plant, a partial load
operation with the load being kept constant is considered. In this
case, by water spray by the spray nozzle 17 at the upstream side of
the compressor 1, power for the compressor 1 is reduced and a
working fluid for the turbine 3 increases, whereby the same load
operation can be maintained with a smaller amount of fuel. That is,
a thermal efficiency at a partial load can be improved by the water
spray.
In the case of intermediate openings of the compressor inlet guide
vanes, a spray quantity also is decreased proportionally to a
decrease in a compressor inlet air flow rate. For example, a ratio
of the water spray quantity to a compressor inlet air quantity is
set or corrected, corresponding to an angle of the compressor inlet
guide vanes, independently of a rated load operating condition.
Thereby, a stable operation can be executed according to changes in
characteristics of the compressor and turbine from a partial load
operating condition to a rated load operating condition.
FIG. 3 indicates that a larger ratio of water spray quantity can be
applied in the case of a larger opening of the compressor inlet
guide vanes, however, since it depends on the types of gas turbines
and the characteristics and operation methods of the combustors
mounted thereon, it may be set so that the characteristics of each
component of individual type of machines are reflected.
Further, a water spray quantity of the spray nozzle 17 is
controlled on the basis of output, atmospheric pressure, etc, the
spray quantity may be controlled so as not to exceed a limit value
based on the compressor inlet guide vane openings. For example, in
the case of control of water spray quantities based on the
atmospheric pressure, a water spray quantity for each compressor
inlet guide opening in FIG. 3 is set as a water spray limit
quantity of FIG. 2B, and water spray injection planned line with a
prescribed margin can be set. In an actual operation, when a water
spray quantity limit value is determined, the control unit 35 sends
signals controlling the openings of the feed water regulating valve
22 and the atomizing air flow adjusting valve 31 so that the really
effective water spray quantity does not exceed the limit value.
Thereby, in the case of control based on the water spray injection
planned line, even if a rapid increase in the spray quantity occurs
because of a rapid load change or for any other reasons, the gas
turbine itself can be protected by using the water spray quantity
limit line.
A third embodiment of the present invention will be described
hereunder, referring to FIGS. 1, 2A, 2B, 4, 5A, 5B and 6.
In the present embodiment, a water spray quantity from the spray
nozzle 17 is controlled on the basis of the atmospheric temperature
and humidity. Concretely, a water spray quantity is made more when
the atmospheric temperature is higher than when low and the water
spray quantity is made larger when the humidity is lower than when
high.
The present embodiment has basically the same construction as the
first embodiment. The present embodiment is provided with a
temperature detecting device 38 and humidity detecting device 75 at
the upstream side of the spray nozzle 17, for example within the
intake chamber 11, in addition to the construction of the first
embodiment. Signals from the detectors are input in the control
unit 35 and a water spray quantity of the water spray nozzle 17 is
controlled according to the signals. FIG. 4 indicates a water spray
quantity limit line with respect to the atmospheric temperature and
humidity.
In a method of water spraying, a B line in FIG. 2A has been set in
advance, and a water spray quantity is increased until a required
output is output. However, in a case where an extent of aged
deterioration due to contamination of the compressor of the gas
turbine itself is large, and a case where a difference between
individual machines, caused by machining tolerance in the same kind
of machines is large, in order to take out of outputs of the B
line, a lot of water is needed to be injected. When an excessive
amount of water is injected into the gas turbine, a condition of
flow in the compressor is deviated from a designed flow condition,
a margin for surging decreases and an unstable operation of the
combustor is caused. Therefore, it is protected by the water
injection limit line determined according to the atmospheric
temperature and humidity, indicated by FIG. 4. In this case, in a
case where the above-mentioned aged deterioration and difference
between individual machines are large, a water spray quantity may
reach the water injection limit line before an output reaches the
output of the B line, so that a target output can not be obtained,
however, the gas turbine is protected from water injection of an
excessive quantity.
Further, in a water spray method, in the case where a planning
water injection quantity has been determined in advance with
respect to the atmospheric temperature, as shown in FIG. 2B, also,
the gas turbine itself can be protected with respect to a rapid
increase due to any reasons.
As shown in FIG. 4, the water spray quantity limit line is
determined according to the atmospheric temperature and humidity.
As items limiting a spray quantity, there may be a water droplet
quantity introduced inside the compressor, a quantity of humidity
introduced in the combustor, a compressor inlet temperature, a pump
capacity in the feed water system, designed pressure of the feed
water piping, a feed water apparatus supply capacity, etc. The pump
capacity of the feed water system, the designed pressure of the
feed water piping, the feed water capacity, etc. of them are not
referred to because usually, their capacities are assumed to have
been studied sufficiently at the time of design. Therefore, as
restricting conditions given by the gas turbine itself, a water
droplet quantity introduced into the compressor, a humidity
quantity flowing into the combustor and a compressor inlet
temperature are totalized to determine The water spray quantity
limit line as indicated in FIG. 4.
The water droplets introduced inside the compressor are evaporated
during flow-down inside the compressor, whereby heat is absorbed
from the ambient air and the temperature inside the compressor is
lowered. Since a decrease in temperature increases the density of
the air, axial flow velocity inside the compressor decreases, a
velocity triangle is deviated from a designed point at the
downstream stage. During usual operation, the axial flow velocity
of compressor after stage decreases when the atmospheric
temperature is low. Therefore, an operating condition inside the
compressor changes, by water spray, to a condition close to the
condition of normal operation at a low atmospheric temperature
without water spray. Therefore, when the atmospheric temperature is
low, an operating condition within the compressor has exceeded an
inherently allowable design range by water injection of a small
quantity, on the contrary, when the atmospheric temperature is
high, a water spray quantity can be increased. An operating
condition deviated from a design point in this manner is called as
mismatching within the compressor, it has reduced a margin for
surging. Since the mismatching within the compressor is caused by
evaporation of water droplets within the compressor, a quantity of
water droplets having been not evaporated in the intake duct 13 and
having entered the inside of the compressor cause a problem, and
the mismatching is not influenced by compressor inlet humidity due
to water evaporated in the intake duct 13. However, a quantity of
evaporation of water droplets in the intake duct 13 is determined
by the atmospheric temperature and humidity, and a compressor inlet
temperature is determined by the quantity of evaporation of water
droplets in the intake duct. Further, an allowable quantity value
of water droplets introduced into the compressor is determined by
the compressor inlet temperature, so that finally, a water spray
quantity limit line with respect to the compressor is determined by
correlation of the atmospheric temperature and humidity.
On the other hand, a quantity of humidity flowing in the combustor
causes an unstable operation. Further, since the temperature of an
air flowing in the compressor decreases by evaporation of water
droplets within the compressor, when the gas turbine is operated at
the same temperature, a quantity of injected fuel increases and
backfire of flames becomes easy to occur. Therefore, since all
quantity of humidity flowed in the combustor influences on an
operation of combustor, a water spray quantity limit line with
respect to the combustor is determined by correlation of the
atmospheric temperature and humidity.
A compressor inlet temperature may cause an icing phenomenon at the
compressor inlet when the atmospheric temperature is low such as in
winter season, icing occurrence is determined by the atmospheric
temperature and humidity.
The water spray quantity limit line is set by associating or
synthesizing the above-mentioned matters. However, according to
types of gas turbines, considered are the case where the
characteristics of the compressor are influential over all over
operational atmospheric temperatures, the case where the
characteristics of the combustor are influential on the contrary,
and the case where the characteristics of the compressor are
influential when the atmospheric temperature is low and the
characteristics of the combustor are influential when the
atmospheric temperature is high. In any of the cases, the water
spray quantity limit line is determined by the atmospheric
temperature and humidity.
After the water spray quantity limit line is determined based on
the atmospheric temperature and humidity at the time of a gas
turbine operation, the control unit 35 of FIG. 1 sends signals
controlling openings of the feed water regulating valve 22 and the
atomized air flow regulating valve 31 so that a real effective
water spray quantity does not exceed the limit value.
An effective water quantity is a water spray quantity obtained by
subtracting a quantity of drain occurred in the intake duct 13 from
a quantity of water sprayed in the intake duct 13 at the upstream
side of the compressor 1. The effective water quantity is indicated
by Gw3 in FIG. 5B. Further, a water quantity evaporated within the
intake duct 13 of the effective water quantity Gw3 is Gw2. A
remaining water quantity Gw1 is introduced into the compressor in
form of water droplets. In a wet-air diagram of FIG. 5B, for
example in a case where a condition of the compressor inlet before
water spraying is a point A, a water droplet quantity corresponding
Gw2 is evaporated within the intake duct by water spraying to lower
a temperature of the ambient air, and the condition of the
compressor inlet shifts to a point B. When the water spray quantity
is increased further, a quantity Gw1 of water droplets which have
not been evaporated is introduced into the compressor.
Therefore, the effective water spray quantity can be calculated
from an indication value Xs3 of a humidity detection device 55 for
a compressor discharge air, an indication value Xs1 of a humidity
detection device 75 at the upstream side of the injection unit
upstream of the compressor, as shown in FIG. 6. The indication
value of the humidity detection device may be relative humidity,
however, by setting the device so as to put out absolute humidity,
an effective water spray quantity can be calculated only by
subtracting an indication value Xs1 of the humidity detection
device 75 upstream of the injection unit from an indication value
Xs3 of the humidity detection device 55 for compressor discharge
air. Humidity detection signals are sent to the control unit 35 and
an effective water quantity Gw3 is calculated.
Referring to FIG. 6, an example of the humidity detector will be
explained hereunder.
In the case where a discharge air from the compressor is used for
water atomizing spray air, the piping branches at the downstream
side of the air shut-off valve 27 and an air pressure regulating
valve 28. A branch pipe 59 is connected to a sampling tank 56 for
measuring absolute humidity at the bottom. A flow adjusting valve
58 mounted on the branch pipe adjust a sampling air so that an
ambient temperature of the humidity sensor 55 does not rise above a
durability temperature. Considering the case of occurrence of
drain, a drain discharge valve 57 is provided on the lower side of
the sampling tank 56. Air supplied to the sampling tank 56 rises in
the tank to reach a ventilation hole 76. The above-mentioned
humidity sensor 55 is inserted to the position of the ventilation
hole 76 so that supplied air always contacts with the humidity
sensor 55. During an operation, air is always continuously flowed
into the sampling tank 56 under this condition and measure.
Further, in the case where extraction air from the middle stage of
the compressor is used as water atomizing spray air, a measuring
pipe may be connected to the discharge casing of the compressor or
a combustor mounting casing for directly measuring humidity.
Further, an effective water spray quantity may be calculated by
subtracting a quantity of drain in the intake duct from an
indication value of the water flow meter. In this case,
practically, it is difficult to detect instantaneous values of the
drain quantities occurred in the intake duct, so that usually an
integrated value is detected. Therefore, it is effective in the
case where a continuous operation is effected for 1 to 2 hours
under the same condition in gas turbine performance test, etc. and
the performance is detected by time-averaging the value. However,
it is not suitable for monitoring gas turbine operating conditions.
In order to solve this problem, it is carried out by making a
function of a drain quantity occurred in the intake duct to a water
spray quantity in advance. For example, such a function is formed
that a drain occurrence quantity increases as a water spray
quantity increase.
A fourth embodiment of the invention will be described hereunder,
referring to FIGS. 1, 5A, 5B and 6.
In the present embodiment, a water droplet quantity from the water
spray nozzle 17 is controlled on the basis of the temperature of an
inlet air entering the compressor. Concretely, for example, a water
spray quantity from the water spray nozzle 17 is made more when the
compressor inlet temperature is higher than when low.
Alternatively, a limit value of water spray quantity is made
variable so as to become higher when the compressor inlet
temperature is higher than when low.
Further, by inputting the compressor inlet temperature, compressor
discharge humidity and humidity of compressor discharge air, a
water spray quantity from the water spray nozzle 17 is controlled
on the basis of the values.
This embodiment, basically, can have a similar construction to that
of the first embodiment. That is, in addition to the construction
of the first embodiment, a temperature sensor 36 and a humidity
sensor 61 are provided on the intake duct 13 in the vicinity of the
compressor inlet, on the downstream side of the injection unit 17.
A humidity sensor 55 is provided so as to communicate with a
compressor discharge air. Signals form the sensor 55 are input into
the control unit 35 and a water quantity of the water spray nozzle
17 is controlled on the basis of the signals.
In some kinds of gas turbines, the stability of combustors is very
excellent and in some cases, a factor influential to determining
the water spray quantity limit line is mismatching within the
compressor. For example, in a case where the combustor is a type of
oil-burning diffusion combustion of which the construction is
relatively simple, the combustor can be considered to exhibit a
stable operation, being little influenced by a quantity of steam
contained in the combustion air, compared with combustors of
oil-burning preevaporation/premixing combustion and gas-burning
premixing lean combustion. In this case, a water spray quantity is
limited by mismatching within the compressor and lowness of
compressor inlet temperature in a winter season.
A limit line of a quantity of water droplets introduced inside the
compressor with respect to compressor inlet temperature is set as
shown in FIG. 5A. Thereby, water spray quantities are made variable
according to compressor inlet temperatures. Thereby, it is possible
to suppress mismatching within the compressor, caused by compressor
inside evaporation of water droplets introduced in the compressor
under a condition of water droplets which remain without being
evaporated in the intake duct. Thereby, the gas turbine itself can
be protected. A humidity quantity corresponding to Gw1 indicated in
FIG. 5B is limited on the basis of a compressor inlet
temperature.
Further, in the same manner as in the second embodiment, the
compressor inside water droplet introduction limit line may be set
as a function based on the compressor inlet temperature and angle
of the compressor inlet guide vanes 7.
When the system is really operated, the compressor inside water
droplet introduction quantity limit line is determined on the basis
of compressor inlet temperature at the time of operation of the gas
turbine, the control unit 35 in FIG. 1 sends signals for
controlling openings of the feed water flow regulating valve 22 and
water atomizing air flow regulating valve 31 so that a true water
droplet quantity introduced in the compressor during operation does
not exceed the limit value.
A compressor inlet temperature is detected by the gas temperature
sensor 36 arranged between the downstream side of the injection
unit and the compressor inlet.
A compressor inside water droplet introduction quantity Gw1
indicated by Gw1 in FIG. 5A, 5B can be computed from an indication
value of the humidity sensor 55 for compressor discharge air and an
indication value of the humidity sensor 61 set between the
downstream of the injection unit and the compressor inlet. The
indication value of the humidity sensor may be relative humidity,
by setting it in advance so as output absolute humidity, Gw1 can be
obtained by subtracting an indication value Xs2 of the humidity
sensor 61 downstream of the injection unit from an indication value
Xs3 of the humidity sensor 55 for compressor discharge air.
Detection signals of the humidity are sent to the control unit 35
in which a compressor inside water droplet introduction quantity
Gw1 is computed.
Referring to FIG. 6, an example of a measuring device of absolute
humidity of the compressor intake portion 14.
A measuring pipe 60 for sampling humidity is connected to the
bottom side of a sampling tank 62. The measuring pipe from the
upper portion of the sampling tank 62 is connected to a vacuum pump
66. Air inside the compressor intake portion 14 is introduced into
the sampling tank 62 and the humidity is measured. The reason that
the measuring pipe 60 is connected to the bottom side of the tank
62 and led to the vacuum pump from the upper portion of the tank is
because of preventing the humidity sensor 61 from contacting with
drain. Further, a sampling air flow regulating valve 63 is mounted
on the measuring pipe 60 and a drain discharge valve 64 is provided
on the bottom of the sampling tank 62.
An absolute humidity Xs2 of the compressor intake portion 14, used
for calculation of a compressor inside water droplet introduction
quantity Gw1 can be measured by continuously flowing air to the
sampling tank. The compressor intake portion 14 becomes negative
pressure to the atmospheric pressure because of pressure loss of
the intake duct 14. Use of the measuring means of this construction
prevents that an air flows back from the atmosphere into the
compressor intake portion 14 and measurement of the absolute
humidity of the compressor intake portion 14 is impossible, and
make it possible to execute a suitable measurement.
Further, as for a compressor inside water droplet introduction
quantity Gw1, an effective water spray quantity is directly
obtained by subtracting a drain quantity in the intake duct from an
indication value of the water flow meter, and the quantity Gw1 can
be computed by subtracting therefrom a quantity of water evaporated
within the intake duct. In this case, the quantity of water
evaporated within the intake duct is calculated by subtracting an
indication value Xs1 of the humidity sensor 75 upstream of the
injection unit from an indication value Xs2 of the humidity sensor
61 downstream of the injection unit. The quantity of drain occurred
within the intake duct can be made, in advance, into such a
function that it increases as a water spray quantity increases, for
example.
Further, it is preferable to provide a mode switch by which water
is sprayed according to months and days, and time. As for a
condition of months and days and time, from April to November, from
nine o'clock to 18 o'clock as the time of a large electric demand
or the time when a gas turbine output lowers according to elevation
of the atmospheric temperature are taken as the condition. Thereby,
the time for use of the output augmenting apparatus can be made
clear, so that it is easy to maintain and manage the equipment,
etc.
A fifth embodiment of the present invention will be described
hereunder, referring to FIGS. 1, 8, 9, 10, 11A and 11B.
In this embodiment, the intake duct 13 is provided with a plurality
of water spray nozzles 17, and it further comprises a water feed
apparatus, main feed water piping in which water flows from the
feed water apparatus, a feed water header causing water from the
main feed water pipe to branch into a plurality of feed water
pipes.
In the case of two-fluid nozzles, air supplied to the water spray
nozzles, and a construction therefor comprises an air supply
apparatus, a main air pipe in which air from the air supply
apparatus flows and an air supply header causing air supplied from
the main air pipe to branch into a plurality of air supply pipes in
the same manner as in the case of water. The air supply pipes are
connected to the water spray nozzles.
In this manner, the water spray nozzles 17 are divided into a
plurality of systems, and the systems (the number of the water
spray nozzles) used are controlled so that the number of the
systems in which water is supplied becomes larger when a water
spray quantity is more than when less.
The control unit controls so as to change the number of the water
spray nozzles 17 used for water spray, corresponding to water spray
quantities.
The present embodiment, basically, may have a similar construction
to that of the first embodiment. That is, in addition to the first
embodiment construction, a temperature detector 36 and humidity
detector 35 are provided, for example, on the intake duct 13 in the
vicinity of the compressor inlet at the downstream of the water
spray nozzles 17. The humidity detector 55 is provided so as to
communicate with compressor discharge air. Signals form the
humidity detectors are input into the control unit 35 to control a
water quantity of the water spray nozzles 17 on the basis of the
signals.
Water spray characteristics in a case where two fluid nozzles are
used are shown in FIG. 8. A water/air ratio is defined by a volume
ratio of atomizing air quantity and water spray quantity. Since
spray pressure decreases as a water quantity decreases under the
condition that an air water ratio is constant, particle size of
water droplets becomes large. Further, when one-fluid nozzles are
used, also, since spray pressure decreases as a water quantity
decreases, particle size of water droplets becomes large.
When water droplets sprayed from the water spray nozzles 17 becomes
large, erosion occurs by impingement of the water droplets on the
compressor blades, there is the possibility that the performance of
the compressor is worsened. However, when the size of the water
droplets is sufficiently small, the droplets do not impinge on the
compressor blades, but they flow with flowing air and evaporate
within the compressor. In order to pass water droplets through
between the compressor blades without impingement on the compressor
blades, although there is a difference by a design condition such
as air flow velocity and shape inside the compressor, the
above-mentioned average particle diameter is smaller than a
prescribed size. For example the diameter is made to be 20 .mu.m or
less. In the intake air humidification cooling system, even if a
water spray quantity changes, it is preferable that the particle
diameter of the water spray droplets is a prescribed value or
less.
In order to solve the problem, as shown in FIG. 1, when a water
spray quantity is small, the flow regulating valves 26
communicating with the spray water pipes are controlled so that a
part of the feed water valves 26 are opened and the others are
closed so as to supply water to a prescribed part of the spray
water pipes 15 communicating with the feed water header 25. In the
same manner, air distributed by the atomizing air header 32 is
controlled by the air flow regulating valves 33. When a water spray
quantity is increased, the number of the opened flow regulating
valves communicating with the spray water pipes is increased. The
number of the air flow regulating valves 33 also is increased
corresponding to the number of the feed water flow regulating
valves 26.
Further, a construction until the spray nozzles may be made by
increasing the number of feed water headers as shown in FIG. 9,
constructing a main feed water header 77 and auxiliary feed water
headers 78,79, and providing feed water flow regulating valves 80
and 81 and feed water flow meters 82 and 83 on feed water lines
connected to the auxiliary feed water headers 78, 79.
In this Figure, also, only one spray water pipe branched from the
auxiliary header 78, 79 is illustrated.
When a water spray quantity is small, only one auxiliary feed water
header 78 is used and so on, whereby water is sprayed by a part of
the number of installed water spray nozzles 17. Thereby, spray
pressure of the spray nozzles can be maintained high, whereby such
control is possible that water supply is in a water spray quantity
range in which water droplets become a certain size or less in the
nozzle spray characteristics of FIG. 8. Further, the spray pressure
increases with increase in the water spray quantity, however, in
order not to exceed the designed pressure in the feed water system,
two of the auxiliary feed water headers 78, 79 are used and so on
when the spray pressure becomes higher than a certain value,
whereby the number of the water spray nozzles 17 used for spray is
increased. The number of the installed auxiliary feed water headers
is determined by the design conditions such as the maximum water
quantity, the number of water spay nozzles, the minimum and maximum
water spray pressures, etc. In FIG. 9, the feed water system is
illustrated in which two auxiliary feed water headers are used.
Further, even in the case where the water spray quantity is small
as a whole, a stable output augmenting operation can be effected by
increasing a water spray quantity per one nozzle and suppressing
variation in average particle diameter of the water droplets,
caused by variation of the water spray quantity.
An operation method in which two auxiliary feed water headers are
used is shown in FIG. 10. In the case of the maximum water quantity
100%, one auxiliary feed water header is used until the water
quantity reaches to 50%. As a switching point at a water quantity
of 50%, by using the second auxiliary feed water header, the two
headers are used supplying water of the same quantity to then until
the water quantity reaches to 100%.
In this manner, according to the present embodiment, even if there
is variation in water spray quantity, water droplets of desired
particle size can be stably obtained, and an operation of variable
output argumentation can be carried out while keeping the soundness
of the apparatus and devices.
Further, by providing the feed water header with a plurality of
feed water pipes 15 without installing auxiliary feed water header,
and by arranging a feed water flow regulating valve and flow meter
at the downstream side of the main feed water header of the feed
water system, it is possible to change the number of water spray
nozzle pipes being operated.
Further, by providing a feed water flow regulating valve for each
water spray nozzle of the feed water system and providing air flow
regulating valve for each water atomizing air nozzle of the air
supply system, without providing auxiliary feed water header, it is
possible to change the number of water spray nozzles being
operated.
A sixth embodiment of the present invention will be described
hereunder, referring to FIGS. 1, 5, 6, 11A and 11B.
In this embodiment, a water quantity or air quantity supplied to
the water spray nozzles 17 are controlled according to a water
spray quantity.
The present embodiment, basically, may have a similar construction
to that of the first embodiment. In addition to the construction of
the first embodiment, the feed water outlet flow regulating valve
26 and atomizing air header flow regulating valve 33 are
controlled, according to a water spray quantity, so as to increase
and decrease an air supply quantity so that an air water ratio
becomes constant (so as to suppress a variation).
Thereby, water droplets of a certain particle size can be obtained
(in the case of a relatively large water quantity it is remarkable)
while suppressing an air flow rate to be small. When air is taken
from the compressor, a lot of air among the intake air can be
supplied to the combustor, and an operation so as to improve output
and efficiency can be carried out.
Further, the feed water outlet flow regulating valve 26 and
atomizing air header flow regulating valve 33 are controlled,
according to a water spray quantity, so as to increase and decrease
an air supply quantity so that a variation of an air water ratio
may be suppressed and, preferably, a air water ratio becomes
constant.
Concretely, an air water ratio is controlled to be small when a
water spray quantity is larger than when small.
Thereby, water droplets of a certain particle size can be obtained
(in the case of a relatively large water quantity it is remarkable)
while suppressing an air flow rate to be small. When air is taken
from the compressor, a lot of air among the intake air can be
supplied to the combustor, and an operation so as to improve output
and efficiency can be carried out.
Nozzle spray characteristics in which particle size of water
droplets is made constant are indicated in FIG. 11A. Since it is
necessary to make an air water ratio larger according to decrease
in the water spray quantity in order to make the particle size
constant, for example, a relationship between a water spray
quantity and an atomizing air quantity or an air water ratio, for
making the particle size constant, have been input in advance into
an arithmetic unit, and then by measuring a water spray quantity by
the feed water flow meter and calculating a necessary atomizing air
quantity, the atomizing air quantity is controlled. Thereby,
variation of particle size according to water spray quantity can be
suppressed. Therefore, erosion occurrence on the compressor blades
by impingement of the water droplets on the blades can be prevented
and a variable output augmenting operation can be executed while
maintaining the soundness of the apparatus and devices.
Alternatively, even by increasing and decreasing a feed water
quantity, even by changing the feed water header outlet flow
regulating valve 26 so as to make the air supply quantity constant,
according to a water spray quantity, the atomizing air header flow
regulating valve 33 is controlled to be constant. Thereby, a
variable output augmenting operation can be executed while
maintaining the soundness of the apparatus and devices by a simple
control.
For example, spray nozzle characteristics when an atomizing air
quantity is made constant is indicated in FIG. 11B. As indicated in
FIG. 11B, an air flow quantity has be determined on the basis of
the air water ratio at a water quantity of 100% of the water
nozzle, air of a constant quantity is supplied to the water spray
nozzle irrespective of variation in the water spray quantity.
Thereby, the particle size of sprayed water droplets becomes always
a rated size or less, and a variable output augmenting operation
can be executed while preventing occurrence of erosion by
relatively simple control.
A seventh embodiment of the present invention will be described
hereunder, referring to FIGS. 1 and 9.
In this embodiment, when water spray starts, a control is carried
out so that first, supply of atomizing air is started, and then
supply of atomized water is started. Further, when the water spray
is stopped, the control is executed so that first, the supply of
atomized water is stopped, and then the atomizing air supply is
stopped. Further, at the time of a water spray operation, control
devices for feed water and feed air supplied to the spray nozzles
are controlled so as to be throttled on the basis of a gas turbine
trip signal.
The present embodiment, basically, may have a similar construction
to that of the first embodiment. Concretely, the following control
is executed.
When the water spray is started on the basis of a water injection
instruction, first, the extraction air shut-off valve 17 of the
atomizing air system is opened. At this time, air flows by a
quantity of the air exhausted from a cyclone separator 29. Next,
the air flow regulating valve 84 is opened so as to flow by an
initial set flow rate and the air flows into the spray nozzle 17.
After the air passage through the nozzle 17 is completed, the feed
water system is started. The feed water pump 20 is started, the
feed water shut-off valve 21 is opened, and water of an initial set
flow rate is flowed by operation of a feed water flow regulating
valve 80. According to this process, the spray water is atomized by
water atomizing air sprayed, and sprayed from the spray nozzle 17.
Then, a spray water quantity is gradually increased until the water
quantity reaches a water injection instruction value.
Further, in the case where a plurality of auxiliary feed water
headers and auxiliary atomizing air headers are used as shown in
FIG. 9, a switching operation is executed at a water quantity of
50% in FIG. 10 according to an increase in water quantity, the air
flow regulating valve 84 is opened to flow air of a set flow rate,
and then the feed water flow regulating valve 81 is operated to
open. In this manner, by flowing air of a set flow rate first, it
is possible to maintain a water droplet atomizing characteristics
even in the process of increasing a quantity of water.
A process of stopping the water spray is explained, referring to
FIG. 9. First of all, the feed water shut-off valve 21 is closed,
and then the feed water flow regulating valves 80, 81 are fully
closed. Here, since in some cases, water downstream of the feed
water flow regulating valve is sprayed by injection of atomizing
air for several minutes, after time passage for a certain time
after stopping of supply of feedwater, the extraction air shut-off
valve 27 is closed, and the air flow regulating valves 80, 81 are
fully closed. In this manner, in the water spray stopping operation
process, also, the air spraying is stopped after the feedwater is
stopped, whereby the water atomizing characteristics can be
maintained after the stopping.
Thereby, water spray starting or stopping operation can be executed
while maintaining the soundness of the apparatus and devices.
Further, at the time of gas turbine trip during the water spray
operation, the feedwater shut-off valve 21 and the extraction air
shut-off valve 27 are fully closed by a trip signal. In this case,
although atomizing air sprayed is lacked and water of large
particle diameter in the feed water duct is sprayed or the water
drops by difference in weight, it occurs for a short time, so that
such a problem as erosion of the compressor blades is not caused
thereby.
Further, concretely, first, an instruction of stopping water spray
is issued on the basis of a signal of gas turbine trip. Then an
instruction of decreasing the compressor inlet guide vane opening
is issued. Thereby, the soundness of the plant can be secured
further at the time of gas turbine trip.
An eighth embodiment of the present invention will be described
hereunder, referring to FIGS. 1, 12A and 12B.
In this embodiment, by detecting a temperature distribution of air
at the inlet of the compressor 1 in a peripheral direction, a
control is carried out so that a temperature deviation does not
exceed a prescribed value.
The present embodiment, basically, may have a similar construction
to that of the first embodiment. In this embodiment, a plurality of
temperature detectors 36 are further arranged on the intake duct 13
as shown in the section taken along line A--A of FIG. 12A.
Water droplets 40 injected from injection nozzle 17 are partly
vaporized within the intake duct 12 thereby dropping the
temperature of ambient air, and are introduced into compressor 1.
At this time, when a water quantity supplied from some of a series
of water spray pipes 15 is insufficient due to clogging or the like
of spray nozzle 17, a difference in measured temperatures occurs
when intake duct air temperature detectors 36 are provided at a
plurality of positions. Since nonuniformity of flow at the intake
portion will normally cause unstable operation of the compressor,
uniformity in the temperatures is also required to be ensured.
Nonuniformity or deviation of temperature in the circumferential
direction at the intake portion of the is compressor implies that
correcting revolution numbers of the compressor differ in the
circumferential direction, which causes mismatching between stage
characteristics within the compressor.
Further, in the case where the temperature deviation at the inlet
of the compressor is due to the above-mentioned deviation of water
flow, there occurs a difference in amounts of water droplets to be
introduced into compressor 1 without having been vaporized within
intake duct 13 in the circumference direction of the intake
portion. Since water droplets introduced into compressor 1 serve to
drop ambient temperatures of a main air stream within compressor 1
by being vaporized therein, when a deviation of water droplet
distribution in the circumference direction is large, there occurs
that a temperature drop in a particular portion within the
compressor becomes large whileas a temperature drop in another
portion becomes small, thereby further deteriorating the
circumferential temperature deviation within the compressor.
Therefore, there may be considered such a case where an excess
drift water exceeding the limit value is unintentionally allowed to
flow partially within the compressor although the operation within
the injection water limit line is intended.
Further, when use of the inlet temperature and humidity of
compressor 1 is considered for the control of water quantity, the
above-mentioned temperature deviation will affect the control of
water quantity, and will cause such a case where an excess quantity
of water over the water quantity limit value is infected, or
contrarily an adequate amount of water which is required for
obtaining a target gas turbine output cannot be injected.
A value is predetermined arbitrarily as an allowable value for
temperature deviations, temperature signals at a plurality of
points detected by air temperature detector 36 indicated in FIGS.
12A, 12B are transmitted to control unit 35, then in the case when
a temperature deviation exceeds the predetermined allowable value,
the control unit controls the opening of the feed water header
outlet flow regulating valve 26 such that a supply water quantity
to be supplied from each water spray pipe 15 to its spray nozzle 17
becomes constant thereby suppressing the deviation within the
allowable value. For example, in such a case where injection nozzle
17 is clogged by foreign matters such as rust accumulated in the
piping, since a feed water pressure in each water spray piping 15
is the same, and since a water quantity to flow into a particular
water injection piping having many clogged nozzles decreases than
quantities in other water spray piping, there results in a
temperature deviation. Therefore, in order to balance water flows
among the water spray piping, openings of the feed water header
outlet flow regulating valves 26 of other water spray piping
without being subjected to clogging are decreased. Thereby, the
temperature deviation at the inlet of the compressor is eliminated
upon balancing of flows in respective water spray piping 15.
However, since the feed water quantity drops due to the decreased
opening of the feed water header outlet flow regulating valve 26,
the control unit 35 sends an open valve operation signal to the
feed water flow regulating valve 22 to raise the pressure of the
feed water header such that an indication by water flowmeter 23
increases to a target water flow. Further, when the feed water
pressure is raised, a quantity of water droplet atomizing air
becomes insufficient, thereby, the control unit 35 sends an open
valve operation signal also to the air flow regulating valve 31 to
raise its supply pressure and control the air flow to become at a
target value.
Thereby, partial occurrence of icing or stalling is suppressed and
a high output operation will be possible while securing the
soundness of the apparatus and device.
Further, instead of the construction shown in the section of A--A
of FIG. 12A, an air temperature detector 37 can be arranged at the
upstream side of the compressor inlet guide vanes as shown in the
section B--B of FIG. 12B. The section B--B is a section upstream of
the compressor inlet guide vanes 7. This construction can have a
similar effect to the construction shown by the section A--A. The
air temperature detectors 37 are arranged at the inlet of the
compressor inlet guide vanes 7 at an interval in the peripheral
direction, preferably, at an equi-interval, whereby more precise
temperature deviation can be detected, abnormality of the apparatus
and devices can be detected precisely and maintenance of the
apparatus and the devices can be effected.
Although an allowable value of preset temperature deviation should
be set to different values according to types or kinds of gas
turbines, in the present invention, it can be set to 15.degree. C.
or lower.
An example of operation of the present invention will be described
hereunder, referring to FIGS. 1 and 13.
FIG. 13 indicates icing limit at the inlet of the compressor 1.
For example, in the case of atmospheric condition being 10.degree.
C. and relative humidity being 30%, it is located at point A in
FIG. 13. Upon vaporization of a portion of injected water between
the downstream side of the water injection unit and the upstream
side of the compressor, an inlet temperature of the compressor 1
drops theoretically to 3.5.degree. C. at point C with a relative
humidity of 100%. However, an air velocity in the vicinity of the
compressor inlet guide vane 7 is accelerated to approximately 200
m/s. Thereby, a static temperature of air drops, and a recovery
temperature on the surface of blades of the compressor inlet guide
vane 7 decreases by 2-3.degree. C. Therefore, there is a
possibility for water droplets introduced into the compressor to
freeze on the wall surface of casing and on the compressor inlet
guide vane 7.
When an icing phenomenon takes place, the output of the gas turbine
drops due to a decrease in quantity of intake air to the compressor
1. Further, there is a possibility that the compressor blade is
damaged by periodical scattering of grown-up ice. Still further in
the case where partial icing in the circumferential direction at
the inlet of the compressor takes place, intake air quantities
sucked into the compressor become uneven in the circumferential
direction, thereby causing unbalanced vibrations of a rotating
portion of the gas turbine or unstable operation of the
compressor.
In actual operation, it is required to preset a lower limit value
of temperatures, which should be determined with an adequate margin
in consideration of an opening of compressor inlet guide vane 7
under operation, a temperature deviation in the circumferential
direction in the inlet of compressor 1, and respective variations
and precision of measurements of the air temperature detectors 36.
In this embodiment, it is preset at 15.degree. C. In FIG. 13, for
example, the lower limit value is set at 5.degree. C., and a region
3 which is lower than 5.degree. C. is defined as a water spray
prohibit region. Therefore, in the case of FIG. 13, a water spray
allowable region is until point B in which an inlet temperature of
the compressor 1 is 5.degree. C. and a relative humidity is
75%.
In FIG. 13, in the case where an atmospheric condition is located
in region 1, it does not occur theoretically that any inlet
temperature of the compressor 1 becomes lower than 5.degree. C.,
thereby eliminating any water spray limitation against icing.
Further, in the case where its atmospheric condition is located in
region 2, since it is possible for the inlet temperature of the
compressor 1 to drop below 5.degree. C. and enter region 3, the
water quantity is controlled such that the inlet temperature of the
compressor 1 will not drop below 5.degree. C. At this time, since
any partial icing at the inlet of the compressor should not be
allowed, the same water flow control as in the first embodiment of
the invention is executed such that every detected values of
temperature signals of air temperature detectors 36 will not drop
below 5.degree. C.
When the atmospheric condition enters region 3 of FIG. 13 during
operation, namely, when a dry bulb temperature of the atmospheric
condition becomes below 5.degree. C., since icing phenomenon starts
in two or three minutes, it becomes necessary to stop water supply
speedily, thereby, the control unit 35 sends a closing valve
operation signal to the feed water shut-off valve 21. Otherwise,
the feed water pump 20 is subjected to emergency stop.
In the case where the atmospheric condition of FIG. 6 is in region
2, that is, a dry bulb temperature of the atmosphere is below
5.degree. C., since a water spray quantity for control in actual
operation becomes small, an increase in output of the gas turbine
to be augmented is limited, thereby providing less advantage.
Therefore, without allowing the water control to be executed to the
verge of icing, when the wet bulb temperature drops below 5.degree.
C., the control unit 35 sends a closing valve operation signal to
the feed water shut-off valve 21. Otherwise, the feed water pump 20
is subjected to emergency stoppage. In this case, the possibility
of icing is completely eliminated, thereby ensuring a safer
operation.
In the suction chamber 11 in FIG. 1, the atmospheric condition
detector 38 and atmospheric humidity detector 75 are installed. The
atmospheric condition detector 38 and atmospheric humidity detector
75 may be placed anywhere in the upstream side of the water
injection unit provided that they are not affected by rain drops.
As a result of detection by the atmospheric temperature detector 38
and atmospheric humidity detector 75, it is found in which region
of FIG. 13 to be positioned. Further, a result of detection by the
compressor inlet suction duct air temperature detector 36 and
compressor inlet gas humidity detector 61 of FIG. 13 may be used as
well. Further, in the case where a signal of detected humidity is a
relative humidity, it may be converted to an absolute humidity in
control unit 35.
A ninth embodiment of the present invention will be described
hereunder, referring to FIGS. 1, 14, 15 and 16.
FIG. 14 is a schematic diagram showing an example of operational
condition detectors surrounding the gas turbine itself relating to
the water flow control.
The present embodiment, basically, may have the construction of the
first embodiment. In addition to the construction, as shown in FIG.
14, a compressor inlet total pressure gauge 39 is provided in the
upper portion of the compressor air intake portion 14, a wall
pressure detector 43 is provided in an inlet casing of the
compressor inlet guide vane 7, a compressor wall pressure variation
detecting pressure sensor 44 is provided in an intermediate stage
of the compressor, a compressor discharge portion temperature
detector 45 and a compressor discharge pressure detector 46 are
provided at a discharge portion of compressor 1, a gas turbine
exhaust gas temperature detector 47 is provided in a gas turbine
exhaust diffuser 8, a bearing vibration detector 42 is provided on
compressor frontal bearing 6, a bearing vibration detector 52 is
provided on a turbine exhaust side bearing 9, a metal temperature
detector 41 is provided on a thrust bearing 5, and a drain
detection level switch 48 is provided in the compressor air intake
portion. It is not necessary to provide all the above-mentioned
detectors, etc.
FIG. 15 indicates changes in the operating conditions of the entire
gas turbine under occurrence of icing phenomena.
Water spray injection starts at point A in FIG. 15, and in
accordance with an increasing quantity of water spray, a compressor
inlet temperature decreases. However, in such a condition where its
atmospheric temperature is too low, an icing phenomenon starts to
takes place from point B, thereby affecting the overall performance
of the gas turbine. When icing phenomenon takes place in the inlet
of the compressor, ice grows on the surfaces of inlet guide vane 7
and the casing, thereby decreasing a frontal annulus area of the
compressor, and thereby decreasing a compressor inlet air flow.
When the compressor inlet air flow decreases, a gas turbine output
drops. Further, since a velocity of air flow in the inlet of the
compressor drops, a pressure on the wall of casing in the inlet
portion of compressor inlet guide vane 7 increases. A decrease in
amounts of air flow at the inlet of the compressor will result in a
decrease in amounts of air flow at the inlet of the gas turbine,
thereby decreasing a discharge pressure of the compressor so far as
the operation is maintained at a constant combustion temperature.
When the discharge pressure of the compressor drops during
operation at the constant combustion temperature, an exhaust gas
temperature of the gas turbine increases. In the case where an
interstage mismatching occurs within the compressor triggered by
the icing phenomenon, an adiabatic efficiency of the compressor
drops remarkably, thereby increasing the discharge temperature of
the compressor.
FIG. 16 indicates changes in overall operational conditions of the
gas turbine under occurrence of a stall phenomenon.
Water injection is started from point A in FIG. 16. With an
increasing quantity of water injection, the inlet temperature of
the compressor decreases, and its output starts to increase.
However, in the case there is a non-uniform temperature
distribution at the inlet of the compressor, a non-uniform
distribution of water droplets introduced into the compressor in
the circumferential direction thereof, any interstage mismatching
within the compressor due to excess water injection therein or the
like, there is a possibility that a blade stalling phenomenon
within the compressor may result in. When there occurs a stalling
phenomenon of blades, a variation of wall pressures of the
compressor increases due to an unstable flow by the stalling. Since
a stalled blade region inhibits its air flow, the quantity of inlet
air of the compressor decreases. The decrease in the quantity of
the inlet air of the compressor causes to decrease the gas
turbine's output. Further, since an air flow velocity at the inlet
of the compressor is caused to decrease, a casing wall pressure in
the inlet portion of compressor inlet guide vane 7 increases. Since
the decrease of the inlet air quantity of the compressor results in
a decrease in the inlet air to the gas turbine, the discharge
pressure of the compressor is also decreased so long as operation
at a constant combustion temperature is maintained. When the
discharge pressure of the compressor is decreased under operation
at a constant combustion temperature, an exhaust gas temperature of
the gas turbine increases. The adiabatic efficiency of the
compressor drops remarkably due to the stalling phenomenon, thereby
increasing the discharge temperature of the compressor. Along with
a rise of variation level of compressor wall pressures, a vibration
in a rotating portion of the gas turbine increases as well thereby
increasing a value of vibration of its bearing.
Although, as mentioned above, the gas turbine itself is essentially
protected by the spray water quantity limit lines, in the long run
there may be considered such a case where use of the same limit
lines alone may not be able to ensure the protection of the gas
turbine itself in consideration of influences such as decreases in
surge margins due to ageing deteriorations of the compressor and
the like. Therefore, it becomes necessary for the operational
conditions in the circumference of the gas turbine inclusive
thereof to be detected and monitored for each item of detection
with respect to its predetermined allowable value of variation.
(1) Since the stall phenomenon within the compressor and the icing
phenomenon on the inlet guide vane 7 of the compressor result in
the drop of the compressor inlet air quantity, it becomes possible
to detect their occurrences by monitoring the compressor inlet air
quantity. In practical operation, in case the compressor inlet air
quantity drops lower than the predetermined allowable value within
a predetermined period of time, the control unit 35 sends a signal
to the feed water flow regulating valve 22 to decrease its opening
so as to decrease the water injection quantity. Further, in case
the allowable value for variation is exceeded, water supply may be
shut off to protect the gas turbine. In this case, the control unit
35 transmits a closing operation signal to the feed water shut-off
valve 21. Otherwise, the feed water pump 20 may be stopped in
emergency.
Here, the compressor inlet air quantity is calculated, for example,
using signals from the compressor inlet total pressure gauze 39
installed in the upper portion of the compressor intake portion 14,
the inlet portion casing wall pressure detector 43 in the inlet of
compressor inlet guide vane 7, and a temperature signal from the
intake duct air temperature detector 36.
Thereby, the icing or stalling phenomena can be surely detected, so
that the soundness of the gas turbine can be surely secured.
(2) Monitoring of the inlet portion casing wall pressure in the
inlet of compressor inlet guide vane 7 is executed in order to
detect the phenomena of stalling within the compressor and icing on
the compressor inlet guide vane, and to achieve the safety
operation of the gas turbine. In case the compressor inlet flow
decreases, the above-mentioned compressor guide vane inlet casing
wall pressure increases. For example, at stoppage of the gas
turbine, a compressor inlet flow quantity becomes 0, at this time,
its casing wall pressure is in the condition of atmospheric
pressure which is a maximum value. With an increasing speed of the
gas turbine and with an increase in the quantity of the inlet air
flow, a velocity of air increases, thereby decreasing its static
pressure, or its casing wall pressure drops.
The above-mentioned compressor guide vane inlet casing wall
pressure is used for calculation of the compressor inlet air
quantity. Both of them can be approximated in a linear function
with an adequate precision being ensured in an actual extent of the
gas turbine operation. Therefore, there is such an advantage that
when the operational condition of compressor 1 becomes unstable,
feed water can be shut off immediately only by referring to the
compressor guide vane inlet casing wall pressure, without need of
executing the result of calculation of the compressor inlet air
quantity.
In an actual operation, the casing wall pressure detector 43 is
installed in the inlet portion of compressor inlet guide vane 7,
and in case where the above-mentioned compressor inlet casing wall
pressure increases over the predetermined limit value for a
predetermined period of time, the control unit 35 is caused to send
a signal to the feed water flow regulating valve 22 to decrease the
opening thereof so as to decrease the quantity of water injection.
Further, in the case of exceeding the allowed value for variation,
water supply may be shut off to protect the gas turbine itself. In
this case, the control unit 35 sends a closing operation signal to
the feed water shut-off valve 21. Alternatively, the feed water
pump 20 may be stopped in emergency.
Thereby, the detectors can be easily installed, the phenomenon of
icing or stalling can be easily detected and the soundness of the
gas turbine can be secured.
(3) Monitoring of the compressor discharge pressure is executed in
order to detect the phenomena of stalling within the compressor and
icing on the compressor inlet guide vane, and achieve the safety
operation of the gas turbine. When the compressor inlet flow
quantity decreases, the above-mentioned compressor discharge
pressure drops so long as under operation at a constant combustion
temperature. A relationship between the compressor inlet air flow
and the compressor discharge pressure can be approximated by a
linear function with an adequate precision in the case of operation
at the constant combustion temperature. Therefore, there is such an
advantage that when the operational condition of the compressor 1
becomes unstable, water supply can be shut off immediately based on
the compressor discharge pressure without need of executing the
result of calculation of the compressor inlet air flow
quantity.
In actual operation, the compressor discharge pressure detector 46
is installed in the discharge portion of compressor 1, and in case
the above-mentioned compressor discharge pressure drops below the
predetermined limit value within a predetermined period of time,
the control unit 35 is caused to send a signal to the feed water
flow regulating valve 22 to decrease its opening so as to decrease
the quantity of water injection. Further, in case the allowable
value of variation is exceeded, water supply may be shut off for
protection of the gas turbine. In this case, the control unit 35
sends a closing operation signal to the feed water shut-off valve
21. Otherwise, the feed water pump 20 may be stopped in
emergency.
Since the pressure level is high and a change in the level can be
rapidly detected, the soundness of the gas turbine can be rapidly
secured upon occurrence of an icing or stalling phenomenon.
(4) Monitoring of the compressor discharge temperature is executed
in order to detect the phenomena of stalling within the compressor
and icing on the compressor inlet guide vane, and to ensure the
safety operation of the gas turbine. In case there occurs a stall
or icing phenomena with an increasing water injection quantity,
since the adiabatic efficiency of the compressor decreases, the
compressor discharge temperature does not drop but remains constant
or increases despite the increased quantity of water. Inherently,
the inlet temperature of the compressor should decrease by water
injection, and in addition, since the temperature of the main air
stream is to be decreased by vaporization of water droplets having
been introduced into the compressor, the compressor discharge
temperature should drop approximately in a linear relationship with
the quantity of infected water. Therefore, an instance that the
compressor discharge temperature does not drop indicates that the
compressor efficiency has dropped due to unstable operation within
the compressor.
In actual operation, the compressor discharge temperature detector
45 is installed in the discharge portion of the compressor 1, and
in case the above-mentioned compressor discharge pressure drops
below the predetermined limit value within the predetermined period
of time, the control unit 35 is caused to send a signal to the feed
water flow regulating valve 22 to decrease its opening so as to
decrease the quantity of water injection. Further, when in excess
of the allowable value of variation, water supply may be shut off
for protection of the gas turbine itself. In this case, the control
unit 35 sends a close operation signal to the feed water shut-off
valve 21. Otherwise, the feed water pump 20 may be stopped in
emergency.
(5) Monitoring of the compressor adiabatic efficiency is executed
in order to detect the stall phenomenon within the compressor and
icing phenomenon on the compressor inlet guide vane, as well as to
detect the interstage mismatching within the compressor, and to
attain the safety operation of the gas turbine. Since the
compressor discharge temperature drops with an increasing quantity
of water injection, apparently, the compressor adiabatic efficiency
increases. However, where there occurs any stall or icing phenomena
with an increased quantity of water injection, the adiabatic
efficiency of the compressor decreases. Further, a subtle
mismatching between interstages within the compressor which does
not appear remarkably from a mere detection of the above-mentioned
compressor inlet flow quantity, discharge pressure and discharge
temperature, can be detected more clearly by the compressor
adiabatic efficiency. The compressor discharge temperature which is
simple because it does not need calculation thereof tends to be
affected by a drop of the compressor discharge pressure when
detecting deterioration of performance of the compressor.
Therefore, there is such a case where the drop of performance of
the compressor cannot be detected after all without calculation of
the compressor adiabatic efficiency.
In practical application, on the basis of measurements by the
compressor inlet total pressure gauge 39 and intake duct air
temperature detector 36 which are installed in the upper portion of
compressor intake portion 14, and by the compressor discharge
temperature detector 45 and compressor discharge pressure detector
46 which are installed in the discharge portion of compressor 1,
when it is found that the above-mentioned compressor adiabatic
efficiency has dropped more than the predetermined limit value
within the predetermined period of time, the control unit 35 is
caused to send a signal to the feed water flow regulating valve 22
to decrease its opening so as to decrease the quantity of water
injection. Further, in case it is in excess of the allowable value
of variation, water supply may be shut off for protection of the
main body of the gas turbine. In this case, the control unit 35
sends a closing operation signal to the feed water shut-off valve
21. Otherwise, the feed water pump 20 may be stopped of its
operation in emergency.
Thereby, even if the atmospheric temperature changes, occurrence of
icing or stalling phenomena can be detected easily, whereby the
soundness of the gas turbine can be easily secured.
(6) Monitoring of gas turbine exhaust gas temperatures is executed
for detection of the stall phenomenon within the compressor and the
icing phenomenon on the compressor inlet guide vane, and for
attainment of the safety operation of the gas turbine. Upon
lowering of the compressor inlet flow quantity, the above-mentioned
compressor discharge pressure drops and the gas turbine exhaust gas
temperature rises so long as the operation at a constant combustion
temperature is maintained. Thereby, there is such an advantage that
in any case where the operating condition of compressor 1 becomes
unstable, feed water can be shut off immediately with reference to
the gas turbine exhaust gas temperatures.
In practical application, the gas turbine exhaust gas temperature
detector 47 is installed in the gas turbine exhaust diffuser 8, and
in case said exhaust gas temperature rises more than a
predetermined limit value within a predetermined period of time,
the control unit 35 is caused to send a signal to the feed water
flow regulating valve 22 to decrease its opening so as to decrease
the quantity of water injection. Further, in case in excess of its
allowable value for variation, water supply may be shut off for
protection of the main body of the gas turbine. In this case, the
control unit 35 sends a closing operation signal to the feed water
shut-off valve 21. Otherwise, the feed water pump 20 may be stopped
its operation in emergency.
Monitoring of fluctuations of gas turbine exhaust gas temperatures
is executed for detection of non-uniform distribution of water
droplets having been introduced into the compressor in the
circumferential direction thereof, unstable operation of the
combustor and for attainment of the safety operation of the gas
turbine. In the case of non-uniform distribution of the compressor
inlet temperatures, and non-uniform distribution of water droplets
having been introduced into the compressor in the circumferential
direction thereof, since there occur variations in quantities of
air and steam to be supplied to the combustor, stable operation of
the combustor is disturbed, and it appears as a variation in
turbine inlet temperatures, that is, as an increased fluctuation in
the exhaust gas temperatures.
In practical application, with reference to the gas turbine exhaust
gas temperature detector 47 installed in the gas turbine exhaust
diffuser 8, when a deviation of the exhaust gas temperature exceeds
the predetermined limit value, the control unit 35 sends a signal
to the feed water flow regulating valve 22 to decrease its opening
so as to decrease the quantity of water Injection. Further, in case
in excess of the allowable value for variation, water supply may be
shut off for protection of the main body of the gas turbine. In
this case, the control unit 35 sends a closing operation signal to
feed water shut-off valve 21. Otherwise, the feedwater pump 20 may
be stopped immediately.
Thereby, upon occurrence of icing or stalling phenomena, they can
be rapidly detected, so that the soundness of the gas turbine can
be rapidly secured.
(7) Monitoring of bearing vibrations is executed for detection of
non-uniformities of compressor inlet air quantities and water
droplets having been introduced into the compressor in the
circumferential directions thereof due to the stall phenomena
within the compressor or the icing phenomena on the compressor
inlet guide vane, and for attainment of the safety operation of the
gas turbine. When there occurs a stalling phenomenon, even if it is
a rotating stall such as to induce forced vibrations on the
compressor blades, or a stall flutter to induce a self oscillation
of compressor blades, it causes vibration levels of the rotating
body to increase. Therefore, there is such an advantage that when
the operational state of compressor 1 becomes unstable, water
supply can be shut off immediately responsive to the bearing
vibrations.
In practical operation, the bearing vibration detector 42 is
provided on the compressor frontal bearing 6, and bearing vibration
detector 52 is provided on the turbine exhaust side bearing 9, and
when a vibration value of said bearings rises in excess of a
predetermined limit value, the control unit 35 is caused to send a
signal to the feed water flow regulating valve 22 to decrease its
opening so as to decrease the quantity of water injection. Further,
when an allowable value for variations is exceeded, water supply
may be shut off for protection of the main body of gas turbine. In
this case, the control unit 35 sends a closing operation signal to
the feed water shut-off valve 21. Otherwise, the feed water pump 20
may be stopped immediately.
Thereby, partial occurrence of icing or stalling phenomena can be
directly detected. The soundness of the gas turbine can be secured
against such phenomena.
(8) Monitoring of metal temperatures of the thrust bearings is
executed for detection of changes in thrust forces in axial
directions of the compressor and the turbine caused by water
injection, and for attainment of the safety operation of the gas
turbine. By water injection, an interstage work distribution within
the compressor is caused to deviate from its original state of the
design. Therefore, a balance between thrust forces in axial
directions of the compressor and the turbine is disrupted, thereby
causing a surface pressure on the thrust bearing to increase, and
thereby causing the metal temperature of the bearing likely to
increase.
In actual operation, the metal temperature detector 41 is installed
on the thrust bearing 5, and when the thrust bearing metal
temperature rises more than a predetermined limit value, the
control unit 35 is caused to send a signal to the feed water flow
regulating valve 22 to decrease its opening so as to decrease the
quantity of water injection. Otherwise, when in excess of an
allowable value for variation, water supply may be shut off for
protection of the main body of gas turbine. In this case, the
control unit sends a closing operation signal to the feed water
shut-off valve 21. Otherwise, the feed water pump 20 may be stopped
of its operation immediately. Unbalance between the compressor 1
and the turbine 3 can be surely detected, so that the soundness of
the gas turbine can be surely secured.
(9) Monitoring of fluctuations in compressor wall pressures is
executed for detection of stalling phenomena within the compressor
and for achievement of the safety operation of the gas turbine. It
is difficult to discriminate, when its atmospheric condition
corresponds to regions 2 or 3 in FIG. 6 described with reference to
the second embodiment of the invention, whether it is a stall
phenomenon or an icing phenomenon simply from a compressor inlet
air quantity, a compressor inlet guide vane inlet casing wall
pressure, a compressor discharge pressure, a discharge temperature,
a compressor adiabatic efficiency, and a gas turbine exhaust gas
temperature. Further, in such a case where there are many stall
regions, and in addition, these stall regions are disposed
uniformly in the circumferential directions, they may not appear
clearly as bearing vibrations. Upon occurrence of a stall
phenomenon, and when it is such a forced vibration on compressor
blades due to rotating stall, since its stall region is caused to
shift toward the circumferential direction, a pressure fluctuation
involved in the stall can be detected directly.
In actual operation, the compressor wall pressure variation
detection pressure sensor 44 is installed in an intermediate stage
of the compressor 1, and when a fluctuation value of the compressor
wall pressure rises more than a predetermined limit value, the
control unit 35 is caused to send a signal to the feed water flow
regulating valve 22 to decrease its opening. Otherwise, when in
excess of an allowable value for variations, water supply may be
shut off for protection of the main body of gas turbine. In this
case, the control unit 35 sends a closing operation signal to the
feed water shut-off valve 21. Otherwise, the feed water pump 20 may
be stopped in emergency.
Since the stalling phenomenon can be directly detected, the
soundness of the gas turbine can be surely secured.
(10) Monitoring of discharge temperatures of the compressor at a
plurality of points is executed for detection of non-uniformities
of the compressor inlet air quantities and water droplets having
been introduced into the compressor in the circumferential
directions thereof due to icing phenomena on the compressor inlet
guide vane, and for attainment of the safety operation of the gas
turbine. Merely from a compressor inlet temperature alone, it is
difficult to detect a circumferential distribution of the water
droplets having been introduced into the compressor. Further, as a
means for detecting circumferential non-uniformities within the
compressor, this method is more direct than by the gas turbine
exhaust gas temperature and the bearing vibration.
In actual operation, a plurality of compressor discharge portion
temperature detectors 45 are installed uniformly in the
circumferential direction on a same plane in the discharge portion
of the compressor 1, and when a variation in temperatures of the
compressor discharge temperature detectors rises more than a
predetermined limit value, the control unit 35 is caused to send a
signal to the feedwater flow regulating valve 22 to decrease its
opening so as to decrease the quantity of water injection. Further,
when in excess of an allowable value of variations, water supply
may be shut off for protection of the main body of gas turbine. In
this case, the control unit 35 sends a closing operation signal to
the feedwater shut-off valve 21. Otherwise, the feedwater pump 20
may be stopped of its operation immediately in emergency.
Thereby, an icing or stalling phenomenon which occurs partially can
be suitably detected.
(11) Mismatching within the compressor is detected based on an
axial flow velocity at the compressor final stage, thereby
executing a safety operation of the gas turbine. FIG. 17A depicts
each velocity triangle on compressor rotor blades in presence and
absence of water injection in the upper stream of the compressor.
FIG. 17B depicts a relationship of incident angles of the
compressor rotor blades versus quantities of water droplets
introduced into the compressor.
The water droplets having been introduced into the compressor are
vaporized therein, absorbing heat from ambient main air stream, and
lowering the temperature of the main air stream, thereby resulting
in a reduced volume flow rate of air. This reduced volume flow rate
means that the axial flow velocity of the main air flow is reduced,
and its effect appears most significantly in the final stage of the
compressor. When the axial flow velocity drops, an incident angle
of a rotor blade in the inlet of compressor rotor blades becomes
large as indicated in FIG. 17A, thereby tending easily to cause a
positive stall thereof. When a stall occurs, a substantial drop in
the compressor efficiency results in, and in addition, a possible
damage of the blade due to stall flutter is feared to take place,
therefore, this occurrence must be avoided always in the practical
operation.
Therefore, a limit value for an allowable region in which the
incident angle of the compressor rotor blades is allowed to change
is set up, and it is ensured that the changes of its incident angle
are restricted within a range of incident angles which is
applicable corresponding to changes of atmospheric temperatures
under normal operation. In normal operation of the compressor, when
an incident angle of a compressor rotor blade in the rear stage
thereof becomes maximum is when its atmospheric temperature becomes
lowest. In this embodiment of the invention depicted in FIG. 17B,
an incident angle at 0.degree. C. of atmospheric temperature is
defined to be a limit value for the time of water injection. The
axial velocity within the compressor may be calculated at any stage
thereof. However, since the mismatching is most likely to occur in
the final stage thereof, the final stage is selected in this
embodiment.
FIG. 18 indicates a control unit for detecting a mismatching in the
final stage of the compressor by detecting an axial flow velocity
at the compressor final stage, and controlling a water spray
quantity of the spray nozzle 17 on the basis of the detected
value.
The incident angle depicted in FIG. 17B may be considered to be
determined approximately by its axial flow velocity alone provided
that the number of revolutions is constant at its rated value.
Therefore, the quantity of water is controlled such that the axial
flow velocity of the final stage of the compressor is ensured not
to drop below the predetermined limit value, namely, for example,
the axial flow velocity at 0.degree. C. of atmospheric temperature
under normal operation. Instead of the axial flow velocity of the
final stage of the compressor, a calculated incident angle or flow
efficiency may be used for control of the water quantity. In any
case of the above methods, calculation of the axial flow velocity
becomes necessary.
The axial flow velocity at the final stage of the compressor is
calculated on the basis of a compressor outlet flow quantity Gcd, a
compression outlet gas density .rho., and a compressor outlet
annulus area. The compressor outlet annulus area among them is a
constant value which is determined by dimensions of each type of
machines, therefore, it is only required to calculate compressor
outlet flow quantity Gcd and compression outlet gas density
.rho..
Compression outlet gas density .rho. can be calculated if a
pressure, temperature and gas constant at the outlet of the
compressor are known. As its pressure and temperature, detected
values of compressor discharge pressure Pcd and compressor
discharge temperature Tcd may be used. As for gas constant Rwet,
since components of the compressor outlet gas slightly differ from
components of inlet dry air due to vaporization of water droplets
within the compressor, gas constant Rwet may be obtained by
compensating gas constant Rdry of dry air with absolute humidity
Xs3 of the compressor discharge air. Further, in case a ratio of
the quantity of water injection relative to the compressor inlet
air flow is small, since its gas constant is less influenced, gas
constant Rdry of the dry air may be used without correction of
humidity to simplify the calculation.
Compressor outlet flow quantity Gcd is calculated by adding water
droplet quantity Gw1 having been vaporized within the compressor.
To compressor inlet wet-state air quantity Gwet. This is because
that since the entire portion of the water droplets having been
introduced into the compressor will be fully vaporized while
flowing down to the outlet portion of the compressor, in order to
calculate an axial flow velocity at the final stage of the
compressor, it becomes necessary to take into account an increase
in its working gas flow quantity due to vaporized wet contents.
Further, in the case where extraction of the gas from the
intermediate stage of the compressor is executed for use of cooling
the turbine blades, sealing the bearing and the like, an extracted
amount of the gas is subtracted.
Water droplet quantity Gw1 having been vaporized within the
compressor refers to the intra compressor water droplet injection
quantity described in the fourth embodiment of the invention, which
is calculated in the same manner as in the fourth embodiment.
Further, this may be substituted by the effective water injection
quantity described in the third embodiment of the invention, or an
indication by water flowmeter 23 may be used directly for
simplification.
Since a compressor inlet air flow to be calculated by a normal
measuring instrument is in a dry-state, wet-state compressor inlet
air quantity Gwet is calculated by compensating for a slight
difference in gas components due to vaporization of water droplets
within the compressor. For this compensation, absolute humidity Xs2
between the bottom stream of the compressor water injection unit
and the upper stream of the compressor is detected, and wet-state
compressor inlet flow quantity Gwet is calculated using a specific
gravity of the wet air. In order to simplify its calculation, a
dry-state compressor inlet flow quantity Gdry may be used as it is
without compensation.
The control unit 35 calculates an axial flow velocity at the final
stage of the compressor from compressor outlet flow quantity Gcd
and compressor outlet gas density .rho. which have been calculated,
then, in the case where its axial flow velocity is lowered more
than a predetermined limit value, the control unit 35 sends a
signal to the feedwater flow regulating valve 22 to decrease its
opening so as to reduce the quantity of water injection. Further,
when in excess of an allowable value for variations, water supply
may be shut off for protection of the main body of gas turbine. In
this case, the control unit 35 sends a closing operation signal to
the feedwater shut-off valve 21. Otherwise, the feedwater pump 20
may be stopped of its operation in emergency.
Monitoring of the quantity of drain at the inlet portion of the
compressor is executed to prevent an overflow of drain into the
compressor when by any reason the drain within the intake duct
fails to be discharged, and to ensure the safety operation of the
gas turbine and avoidance of wear or erosion of compressor
blades.
In the case where the intake duct 13 in the upstream side of the
gas turbine's compressor is located in the upper direction as
indicated in FIG. 14, if the drain outlet valves 53, 54 in a drain
discharge system are closed by malfunction or the like, a level of
drain in the compressor intake portion will rise as high as it
overflows into the compressor unless some measure is taken. If
drain is allowed to overflow into the compressor, it may cause a
serious problem such as wear of the compressor blades, unstable
operation of the compressor, an increased combustion vibration, a
blow-off of flame in the combustor, increased bearing vibrations
and the like, and thereby resulting in a failure which damages the
gas turbine itself.
An example of drain detection according to the invention is
depicted in FIG. 14. In the bottom portion of the compressor intake
portion, a drain discharge hole is provided, and a drain outlet
pipe 50 is provided with a drain slant to easily discharge the
drain. The drain having been discharged is recovered in a drain
groove. Drain level detector pipe 49 erecting vertically from drain
outlet pipe 50 is provided with a level switch 48. When the drain
level rises above a predetermined limit value, the control unit 35
is caused to send a signal to the feed water flow regulating valve
22 to decrease its opening so as to decrease the quantity of water
injection. Further, when in excess of an allowable value of
variations, water supply may be shut off for the protection of the
main body of gas turbine. In this case, the control unit 35 sends a
close operation signal to the feed water shut-off valve 21.
Otherwise, the feedwater pump 20 may be stopped in emergency.
A tenth embodiment of the invention will be described with
reference to FIGS. 1, 19 and 20.
Control unit controls so as to increase a fuel injection quantity
to the combustor 2 when water spray quantity from the spray nozzle
is more than when small.
FIG. 19 shows an example of detecting the humidity of air supplied
to the compressor and a water spray quantity of the spray nozzle
17, and controlling (or compensating) a fuel injection quantity to
the combustor 2 based on the detected values. FIG. 20 shows an
example of detecting the compressor discharge humidity and
controlling (or compensating) a fuel injection quantity to the
combustor 2 based on the detected values. A gas turbine exhaust gas
temperature according to the absolute humidity of compressor and
steam or water spray quantity of the combustor is compensated. By
changing of setting an exhaust gas temperature control line to be
higher or by compensating an exhaust gas measurement value, a fuel
injection quantity is increased.
It is normal for the gas turbine under a rated load to be operated
at a constant combustion temperature. However, a direct measurement
of a combustion temperature is difficult since its combustion
temperature is extremely high. Therefore, a gas turbine exhaust gas
temperature is measured instead of direct measurement of the
combustion temperature. In order to maintain the combustion
temperature at a constant value, an exhaust gas temperature control
line related to compressor discharge pressures or compressor
compression ratios is predetermined, and a quantity of fuel flow is
controlled so that measured values are on the control line. In a
gas turbine of such a type wherein water injection is carried out
in the upstream side of its compressor, an absolute humidity of air
discharged from the compressor increases more than normal due to
vaporization of water within the intake duct 13 and compressor 1,
thereby resulting in a change of components of the turbine inlet
gas due to its increased moisture component, and thereby changing a
ratio of specific heat of the gas serving as a working medium
within the turbine. In this case, although an effect of its added
moisture content on the turbine efficiency is small, a drop in the
ratio of specific heat due to the changes in the gas components
becomes predominant, and an attempt to maintain the combustion
temperature constantly results in an increase in its exhaust
temperature.
Therefore, in actual operation of the gas turbine, if the same
exhaust temperature control line is used irrespective of a
difference in ratios of specific heat, operation at a combustion
temperature lower than a design value occurs when its moisture
content in the inlet of the turbine becomes large, thereby
preventing the utmost utilization of the output improvement effect
of the invention from being demonstrated.
Therefore, a control is executed so as to increase an injection
quantity of fuel into the combustor 2 when a water injection
quantity from the spray nozzle is lager than when small.
Therefore, as indicated in FIG. 20, by measuring an absolute
humidity of a discharged air from the compressor, an exhaust gas
temperature correction quantity is calculated corresponding to a
change in combustion temperatures depending on its moisture
content. By subtracting the above-mentioned exhaust gas temperature
correction quantity from an actual exhaust gas temperature having
been measured, an exhaust gas temperature correction value for use
in the control of combustion temperatures is calculated. Thereby,
it becomes possible to operate the gas turbine at a constant
combustion temperature for any quantity of water infection, thereby
achieving a maximum output argumentation effect.
Further, depending on a type of combustor, a steam injection or
water injection is executed for its combustor in order to reduce
NOx. Also in this case, its wet content in the inlet of the turbine
increases, thereby changing a ratio of specific heat of the gas
serving as the working medium in the turbine, and when an attempt
is made to maintain its combustion temperature at a constant value,
its exhaust temperature increases. Therefore, by calculating a net
absolute humidity at the turbine inlet from a sum of a steam or
water injection quantity to the combustor and an absolute humidity
of compressor outlet air, then, an exhaust gas temperature
correction quantity corresponding to a change in combustion
temperatures resulting from its wet content is calculated. By
subtracting the above-mentioned exhaust gas temperature correction
quantity from an actual exhaust gas temperature having been
measured, an exhaust gas temperature correction value for use for
controlling combustion temperatures is calculated. Thereby, it
becomes possible to operate the gas turbine at a constant
combustion temperature for any quantity of water injection into the
compressor, and for any quantity of steam or water injection into
the combustor, thereby achieving a maximum output argumentation
effect.
Further, the exhaust gas temperature control line may be corrected
instead of correction of measured exhaust gas temperatures.
A detection means for absolute humidities of compressor discharge
air may be the same as in the third embodiment. Further, the
moisture content in the gas flowing into the combustor may be
calculated as shown in FIG. 19, instead of the direct detection of
the absolute humidity of the compressor discharge air, from an
absolute humidity of the atmosphere under operational conditions
and an effective water injection quantity. In this case,
calculation of the effective water injection quantity is executed
in the same manner as in the third embodiment of the invention.
An eleventh embodiment of the present invention will be described,
referring to FIGS. 1, 21A and 21B.
The present embodiment, basically, may have a similar construction
to that of the first embodiment. In addition to the construction, a
detector for detecting NOx concentration is provided on the exhaust
flow passage of the turbine 3.
By detecting NOx concentration, a water spray injection quantity
from the spray nozzle 17 is controlled not to exceed a limit value.
An example of the control is indicated in FIG. 7-d. In FIG. 7-d,
when the NOx concentration at the gas turbine inlet is higher than
a target NOx concentration, water spray is injected to decrease the
NOx concentration to the target value. In this case, a water spray
injection quantity is within a range which is lower than a maximum
water injection instruction value of FIG. 7-c.
Water spray injection increases a humidity of a compressor
discharge air which is a combustion air for the combustor, and has
the same effect as a NOx decreasing effect due to an increase of
humidity which is caused by water or steam injection into the
combustor. However, the method of water spray injection into the
compressor lowers an air temperature within the intake air duct and
is able to increase an output of the gas turbine by decreasing a
power for the compressor.
Further, as compared with the above-mentioned NOx emission
reduction executed by the water or steam injection into the
combustor, in the present embodiment, a gas that water and air
inside the combustor are homogeneously mixed flows in the
combustor, so that a mixing condition of water and air is better.
There fore, NOx emission can be reduced with simple construction,
suppressing combustion vibrations and maintaining a stable
combustion.
Further, In addition to the water spray injection by the spray
nozzle 17, a case where a mechanism for injecting steam into the
combustor is provided is shown in FIGS. 21A and 21B.
FIG. 21A indicates a relationship between water injection
quantities and NOx concentrations in gas turbine's exhaust gas, and
FIG. 21B indicates a relationship between water injection
quantities and combustion vibration.
In FIGS. 21A and 21B, an operational condition with zero quantity
of water injection in the upper stream of the compressor is defined
to be at point A. When a quantity of steam or water injection into
the combustor is constant, and when the quantity of water injection
in the upstream side of the compressor is increased, a NOx
concentration in the exhaust gas from the gas turbine decreases,
however, combustion vibrations of the combustor increase.
Therefore, the control unit 35 is caused to send a signal to the
feedwater flow regulating valve 22 to decrease its opening and
reduce the quantity of water injection so that the NOx
concentration and combustion vibrations will be within allowable
values, respectively.
Otherwise, in order to hold the combustion vibrations constant
while increasing the quantity of water injection in the upstream
side of the compressor, the quantity of steam or water injection
into the combustor may be reduced. However, there exists a
contradicting relationship that reduction of the quantity of steam
and water injection into the combustor will increase NOx
concentration in the gas turbine's exhaust gas. Therefore, by
monitoring both the above-mentioned combustion vibrations and the
NOx concentration in the exhaust gas, and suppressing both of them
within their allowable values, the quantity of steam and water
injection into the combustor is controlled such that the point of
operation in FIGS. 21A, 21B is caused to shift from point A to
point B, then to point C with an increasing quantity of water
injection.
A twelfth embodiment of the invention will be described hereunder,
referring to FIGS. 1, 22A and 22B.
In this embodiment, a control is executed so as to change a
premixed ratio of the gas turbine according to a time of water
spray injection of a large quantity and a time of water spray
injection of a small quantity. The control is executed so as to
increase a ratio of diffusion combustion when the water spray
injection is larger than when small.
The present embodiment, basically, may have a similar construction
to that of the first embodiment. In addition to the construction, a
detector for detecting NOx concentration is provided on the exhaust
flow passage of the turbine 3, and signals are input into the
control unit 35. Further, combustion vibrations are detected and
the signal is input into the control unit 35. For example, under
the normal operational condition after starting has been completed,
the control unit 35 controls so that a diffusion combustion ratio
becomes more at the time of water spray injection than at the time
of water injection stoppage so as to decrease a NOx emission
quantity, preferably to suppress combustion vibrations in addition
thereto. Further, the control is executed so as to increase the
diffusion combustion ratio when a water injection quantity is
larger when small.
FIG. 22A indicates a relationship of combustor's premixture
combustion ratios versus gas turbine exhaust gas NOx
concentrations, and FIG. 22B indicates a relationship of the
premixture combustion ratios versus combustion vibrations.
When a gas fuel such as a liquidified natural gas or the like is
used as a fuel for the combustor, the premixture combustion and
diffusion combustion are used in combination generally. When its
premixture combustion ratio is increased with an increasing load of
the gas turbine, its gas turbine exhaust gas NOx concentration is
caused to drop, however, there exists a point of operation where
its combustion vibration increases. Therefore, in actual operation
of the gas turbine, an optimal premixture combustion ratio is set
at which both the exhaust gas NOx concentration and the combustion
vibration can be suppressed within their allowable values. Normal
point of operation in the gas turbine is indicated by point A in
FIGS. 22A, 22B. However, in the case where water injection is
conducted in the upstream side of the compressor, the combustion
vibration tends to occur more easily than in normal operation under
the same premixture combustion ratio, thereby shifting its point of
operation to point B. Therefore, in order to suppress its
combustion vibration to the same level as point A of the normal
operating point of the gas turbine, it becomes necessary to
decrease its premixture combustion ratio and to increase its
diffusion combustion ratio. However, when its premixture combustion
ratio is decreased too small, the exhaust gas NOx concentration
will increase. Therefore, its premixture combustion ratio is
decreased to operating point C at which both of the combustion
vibration and the exhaust gas NOx concentration are ensured to be
suppressed within their allowable values.
Fluid conditions change greatly by whether or not water spray
injection is conducted and by variations in water injection
quantities. However, according to the present embodiment, it is
possible to cause the gas turbine to operate at a high output while
maintaining the soundness of the plant by suppressing the
combustion condition to come into instability and suppressing
variations in NOx concentration and combustor pressure.
Water spray injection quantities or water droplet atomizing air
quantities on the upstream side of the compressor are approximately
in proportion with supply pressures of water or atomizing air.
From the characteristics of the spray nozzle 17, a water spray
injection quantity and water supply pressure, and atomizing air
quantity and air supply pressure can be determined univocally.
However, in case where the spray nozzle 17 is choked, an opening
area reduces, so that in order to inject the same water spray
quantity, the supply pressure becomes higher. In an actual
operation, it is impossible to monitor choking of the spray nozzle
by eyes during continuous operation, a choking rate of the spray
nozzle is calculated on the basis of deviations of supply pressure
from the designed value. It is preferable to exchange the spray
nozzle with another in case the choking rate exceeds a
predetermined allowable value of choking rate.
Referring to FIG. 14, a drain preventing apparatus for pressure
detection piping is explained.
Of the pressure detecting piping around the gas turbine main body,
the following needs the drain preventing means, that is, a
compressor inlet total pressure pipe 39 installed on an upper
portion of the compressor intake portion 14, a wall pressure
detector 43 of a casing of the inlet of the compressor inlet guide
vane 7, and a compressor discharge pressure detector 46 at the
discharge portion of the compressor 1. In FIG. 14, only the
compressor inlet total pressor pipe 39 is shown. The measuring
piping 67 has a drain gradient so as to prevent drain from
remaining on the way, and it is provided with a drain recovery tank
69 at the lower portion thereof. The measuring piping 67 and 68 are
connected to an upper portion of the drain recovery tank 69. The
measuring piping 68 connects the drain recovery tank 69 to a
pressure transducer 71. A drain discharge valve 70 is provided on
the lower portion of the drain recovery tank 69. This embodiment
also is applied for the humidity detection piping 59 at the
compressor inlet and the humidity detecting piping 60 for
compressor discharge air.
According to the present invention, a gas turbine and a control
unit Which are able to improve both output and thermal efficiency
by water spray injection into the intake air introduced into the
compressor inlet, along a practical operational control method can
be provided.
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