Note: Descriptions are shown in the official language in which they were submitted.
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CA 02357492 2001-09-20
GAS TURBINE FUEL SYSTEM COMPRISING FUEL OIL DISTRIBUTION
CONTROL SYSTEM, FUEL OIL PURGE SYSTEM, PURGING AIR SUPPLY
SYSTEM AND FUEL NOZZLE WASH SYSTEM
This application is a division of Canadian Patent
Application Serial No. 2,270,672, filed on May 4, 1999.
BACKGROUND OF THE INVENTION:
Field of the Invention:
The present invention relates generally to a gas
turbine fuel system and more specifically to a gas turbine fuel
system comprising a fuel oil distribution control system, a
fuel oil purge system, a purging air supply system and a fuel
nozzle wash system in which fuel oil distribution is controlled
to. be done uniformly to a plurality of fuel nozzles with
enhanced reliability of fuel distribution and residual oil in
fuel pipings and nozzles when gas turbine operation is changed
over to gas fuel from oil fuel is purged effectively so that
load change caused by burning of the residual oil at the time
of purging is prevented.
Description of the Prior Art:
Fig. 9 is a block diagram of an entire gas turbine
fuel system comprising therein a fuel oil supply system, a fuel
oil purge system, a purging air supply system and a compressor
outlet wash system in the prior art. In Fig. 9, a combustor
X comprises therein a plurality, about 20 pieces for example,
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of fuel nozzles X1, Xz disposed along an inner periphery thereof .
The fuel nozzles X1 are supplied with fuel gas from a fuel gas
supply system and the fuel nozzles Xz are supplied with fuel
oil from a fuel oil supply system G. These gas and oil are
changed over to either one thereof to be supplied into the
combustor X for combustion. The fuel oil supply system G, as
mentioned, is a system for supplying therethrough fuel oil and
a fuel oil purge system H is a system for purging oil remaining
in the piping system or fuel nozzles when the fuel is changed
over to gas from oil. A purging air supply system J supplies
therethrough a purging air into the fuel oil purge system H.
A compressor outlet wash system K is a system for injecting
water into a compressor outlet for washing this compressor
outlet which communicates with the combustor. Description will
be made further on each of the above systems.
The fuel oil supply system G will be described first.
In the gas turbine, a stable combustion is required for a wide
range of fuel flow rate from ignition to power output.
Especially, in the low fuel flow rate range at the time of
ignition etc., there is only a small differential pressure of
the fuel nozzles in the combustor, which results in an unstable
combustion. In the recent gas turbine, there are provided a
large number of fuel nozzles of about 20 pieces and there arises
unbalance in the fuel flow rate by the influence of head
difference between upper ones and lower ones of the fuel nozzles
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which are disposed up and down. For this reason, a flow divider
is provided so that fuel is divided to be supplied uniformly
to each of the fuel nozzles. But this flow divider is not
necessarily of a sufficient reliability and thereby often
caused are troubles in the fuel system.
Fig. 10 is a diagrammatic view of the fuel oil supply
system G in the prior art. In Fig. 10, fuel oil is controlled
of flow rate by a flow control valve 11 to then flow through
a piping 12 and enters a flow divider 80 to be divided there
to flow through a plurality of pipings 82 of about 20 pieces
and to be supplied into each of the fuel nozzles XZ of the
combustor X. The gas turbine fuel nozzles XZ are disposed in
about 20 pieces along a circumference and there is a head
difference of about 4 m between the nozzles of upper position
and those of lower position. This head difference produces
unbalance in the fuel flow rate, especially in the low fuel flow
rate range at the time of ignition. For this reason, the flow
divider 80 is provided but this flow divider 80 is constructed
such that a spiral shaft is disposed in a cylindrical body and
while this shaft is rotated, fuel oil is flown into the
cylindrical body to be divided to flow through each of the
plurality of pipings 82 uniformly. A motor 81 is operated only
in the operation start time for ensuring a smooth start of
rotation of the flow divider 80.
Fig. 11 is a view showing relation between load
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transition (fuel flow rate) and system differential pressure
in the prior art gas turbine, wherein as load increases, fuel
flow rate increases from gas turbine ignition time to to rated
speed ( no load ) arrival time t1 and further to time t2 when the
system differential pressure including nozzle differential
pressure comes to a necessary nozzle differential pressure V1.
That is, during the time T from to to t2, the system differential
pressure does not reach the necessary nozzle differential
pressure V1 but it reaches V1 at time t2 to increase more
thereafter. Accordingly, the nozzle differential pressure is
low during the time shown by T and if there is a head difference
between said plurality of fuel nozzles, there occurs unbalance
of fuel flow rate between each of the fuel nozzles, hence the
flow divider 80 is operated so that the unbalance of the fuel
oil between each of the fuel nozzles may be eliminated. But
this flow divider 80 has a very small gap between the inner
rotational body and the stationary portion for its function and
this makes control of foreign matters difficult and has been
often causes of troubles in the fuel system.
Next, the fuel oil purge system H will be described.
Fig. 12 is a diagrammatic view of the fuel oil purge system in
the prior art at the time when the gas turbine fuel is changed
over. In Fig. 12, numeral 1 designates a flow control valve
in a fuel gas system, numeral 2 designates a piping therefor,
numeral 3 designates a fuel gas distributor, which distributes
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the fuel gas to the plurality of fuel nozzles X1 and numeral
4 designates a plurality of pipings, which supply therethrough
the fuel gas from the fuel gas distributor 3 to the respective
fuel nozzles X1.
Numeral 11 designates a flow control valve in a fuel
oil system, numeral 12 designates a piping therefor, numeral
13 designates a header, which distributes the fuel oil from the
piping 12 to the plurality of fuel nozzles Xz and numeral 14
designates a plurality of pipings, which are connected to the
header 13 and supply therethrough the fuel oil distributed by
the header 13 to the respective fuel nozzles Xz. Numeral 26
designates a purging air system piping, numeral 25 designates
an opening/closing valve, numeral 23 designates a drain valve
piping and numeral 24 designates an opening/closing valve
therefor. Combustor X comprises therein the fuel nozzles
X1. Xz.
In the mentioned system so constructed, while the
operation is done with the fuel oil being burned, the fuel oil
flowing through the flow control valve 11 and the piping 12 is
distributed by the header 13 to flow through the plurality of
pipings 14 to the respective fuel nozzles Xz. The fuel oil so
distributed is injected into the combustor X from the fuel
nozzles Xz for combustion there.
When the operation is done with the fuel being changed
over to gas from oil, the flow control valve 11 is closed and
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i.
the fuel gas is led instead into the piping 2 to be supplied
to the fuel nozzles X1 through the fuel gas distributor 3 and
the piping 4. In this case, the previous fuel oil remains as
it is in the pipings 12, 14 and this fuel oil, if left there,
is carbonized to stick there with a fear to cause blockage of
the pipings and nozzles . Hence, it is necessary to remove such
residual oil when the fuel is changed over to gas:
Thus, the opening/closing valve 25 is opened so that
purging air 40 is led into the piping 12 from the purging air
system piping 26. The purging air 40 enters the header 13
through the piping 12 to then flow through the pipings 14 to
the fuel nozzles Xz to be blown into the combustor X. Thereby,
the fuel oil which remains in the piping 12, header 13, pipings
14 and fuel nozzles XZ is all discharged into the combustor X.
This purging of the residual oil is done while the operation
is continued with the fuel gas being supplied and burned in the
combustor X. But there is a considerable quantity of such
residual oil itself in the piping 12, header 13, pipings 14 and
fuel nozzles X2 and also there are provided a large number of
the fuel nozzles Xz and same number of the pipings 14 connected
to the respective fuel nozzles X2. Accordingly, if the residual
oil in these portions is all discharged into the combustor X
and the operation is continued with the fuel gas so changed over,
then the fuel oil so discharged into the combustor X burns so
that the fuel increases beyond a planned supply value, which
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elevates combustion temperature to cause a large load change.
Hence, realization of a fuel oil purge system which does not
cause such a load change has long been desired.
Next, the purging air supply system ,7 will be
described. In the recent gas turbine, there is realized an
operation system wherein fuel is changed over to gas from oil,
as mentioned above. This operation system comprises therein
both of fuel oil system and fuel gas system and it is necessary
to purge fuel pipings and nozzles on the side not used.
Especially in the fuel oil system, oil remains in the pipings
and, if left as it is, is carbonized to stick there and there
is a fear of blockage of the pipings and nozzles.
Fig. 13 is a diagrammatic view of the purging air
supply system J in the prior art gas turbine. In Fig. 13,
numeral 110 designates a gas turbine, numeral 42 designates a
piping for taking out therethrough outlet air of air compressor
and numeral 90 designates an air cooler, which comprises
therein a multiplicity of tubes communicating with the piping
42. Numeral 91 designates a motor for rotating a fan 92 to
thereby supply air to the air cooler 90 and numeral 43
designates a piping connecting to outlet of the air cooler 90.
Numeral 93 designates also a piping, which diverges from the
piping 42 for obtaining air of the purge system and numeral 94
designates a cooler using water 95 for cooling the air from the
piping 93. Numeral 96 designates a piping connected to outlet
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of the cooler 94, numeral 97 designates a drain separator,
numeral 98 designates a piping connected to outlet of the drain
separator 97, numeral 53 designates a pressure elevation
compressor and numeral 99 designates a piping connected to
outlet of the pressure elevation compressor 53. Numeral 100
designates a cooling using water 101 for cooling the air which
has been heated to a high temperature by pressure elevation at
the pressure elevation compressor 53 to an appropriate
temperature as a fuel nozzle purging air. Numeral 48 designates
a piping for supplying therethrough the air which has been
cooled to the appropriate temperature as the purging air at the
cooler 100.
In the mentioned system so constructed, the air of
the compressor outlet of about 400°C is cooled at the air cooler
90 to about 200 to 250°C to be supplied into the gas turbine
110 as a rotor cooling air through the piping 43, wherein a
portion of the air of the compressor outlet diverges from the
piping 42 and is led into the cooler 94 through the piping 93
to be cooled to about 130°C to be then sent to inlet of the
pressure elevation compressor 53. This air is removed of drain
by the drain separator 97 disposed between the pipings 96 and
98. Then, the air is compressed to a predetermined pressure
at the pressure elevation compressor 53 and its temperature is
also elevated to about 200°C. This air of about 200°C is led
into the cooler 100 through the piping 99 to be cooled there
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CA 02357492 2001-09-20
to about 150°C which is appropriate for the purging and is then
supplied to each of the fuel systems through the piping 48 as
the purging air.
Thus, in the purging air supply system, as the inlet
temperature of the pressure elevation compressor 53 becomes
high, there is provided the cooler 94 for cooling the compressor
outlet air. of about 400°C to about 100 to 130°C. Also, as the
air, when compressed at the pressure elevation compressor 53,
is heated to about 200°C, it is cooled again at the cooler 100
to about 150°C. In this kind of system, therefore, there are
needed the coolers 94, 100 or the like, which requires large
facilities and spaces therefor. Hence, it has been needed to
improve these shortcomings and to attain cost reduction.
Next, the compressor outlet washing system K will be
described. Fig. 14 is a diagrammatic view of the compressor
outlet wash system in the prior art. In Fig. 14, letter X
designates a combustor, numeral 112 designates a compressor
outlet and numeral 113 designates a manifold for distributing
wash water in an annular form, as described later. Numeral 114
designates a plurality of wash nozzles, which are provided
along periphery of the manifold 113 for injecting therefrom
wash water into the compressor outlet 112. Numeral 11
designates a flow control valve for fuel oil, numeral 12
designates a piping and numeral 13 designates a header for
distributing fuel into a plurality of fuel supply pipings 14.
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Fuel oil is supplied from the respective fuel supply pipings
14 to a plurality of fuel nozzles X2.
Numeral 60 designates an air control valve for
leading a high pressure air into a wash tank 62 via a piping
61. The wash tank 62 stores therein the wash water for washing
interior of the compressor outlet 112. Numeral 63 designates
an opening/closing valve, through which the wash water flows
to be supplied into the manifold 113 via a piping 64. The wash
water supplied into the manifold 113 is injected from the
plurality of wash nozzles 114 into the surrounding area for
washing the interior of the compressor outlet 112. Numeral 65
designates an opening/closing valve and numeral 66 designates
a piping for supplying therethrough the wash water in a
necessary quantity into the wash tank 62.
In the gas turbine compressor outlet wash system so
constructed, when the compressor outlet 112 is to be washed,
the air control valve 60 is opened and the high pressure air
is led into the wash tank 62 via the piping 61 so that interior
of the wash tank 62 is pressurized. Then, the opening/closing
valve 13 is opened and the wash water is supplied into the
manifold 1I3 via the piping 64. The wash water is injected from
the wash nozzles 114 for washing the interior of the compressor
outlet 112.
On the other hand, as for the gas turbine operation,
fuel oil is led into the header 13 via the flow control valve
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11 and the piping 12 to be distributed there to flow into the
plurality of fuel supply pipings 14 uniformly and is then
supplied into the respective fuel nozzles XZ for combustion.
In the recent gas turbine, there is developed a dual
fuel system in which both fuel oil and fuel gas are usable and
the fuel is changed over to gas from oil, or to oil from gas,
as the case may be. In such a system, if, for example, the
operation done by oil is stopped or is continued with the fuel
being changed over to gas from oil, the fuel oil remaining in
the fuel pipings and nozzles is carbonized to stick there and
there arises a fear of blockage of the fuel pipings and nozzles .
Thus, attempt is being done for providing large scale
facilities by which the fuel pipings and nozzles are purged by
air or the like. But these exclusive purging facilities require
a large apparatus, which are naturally undesirable from
viewpoint of cost reduction.
SUMMARY OF THE INVENTION:
In view of the problems in the prior art gas turbine
fuel system, it is a principal object of the present invention
to provide a gas turbine fuel system comprising a fuel oil
supply system and a fuel gas supply system so that gas turbine
operation may be done with fuel being changed over to either
oil or gas and further comprising a control system in which fuel
is distributed to each fuel piping of said fuel oil supply
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system uniformly in an appropriate flow rate and pressure as
well as a purge system in which, while gas turbine operation
is done with gas fuel, residual oil in said fuel oil supply
system is purged effectively by air or water so that said
residual oil may not be carbonized.
In order to provide said gas turbine fuel system, the
present invention has objects to provide following first to
fourth systems:
First one is a gas turbine fuel oil distribution
control system in which a control valve is employed instead of
a flow divider, said control valve being constructed such that
differential pressure of each fuel nozzle is elevated at the
initial time of gas turbine operation, as well as fuel oil is
distributed so as to flow into each of fuel pipings connected
to fuel nozzles as uniformly as possible so that unbalance in
fuel oil flow rate caused by head difference between each fuel
nozzle is dissolved and unusual elevation of the differential
pressure at the time of high fuel flow rate is prevented.
Second one is a gas turbine fuel oil purge system in
which, when gas turbine operation is done with fuel being
changed over to gas from oil and residual oil in fuel pipings
and nozzles is to be purged, quantity of the residual oil to
be discharged into a combustor is made as small as possible as
well as the residual oil is purged securely to be discharged.
Third one is a gas turbine fuel nozzle purging air
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CA 02357492 2001-09-20
y'
supply system in which compressor outlet air of about 400°C is
cooled at a rotor cooling air cooler to an appropriate
temperature to enter a pressure elevation compressor, thereby
some of coolers are made unnecessary so that construction of
the purging air supply system is simplified, installation space
thereof is reduced and cost of facilities is reduced.
Fourth one is a gas turbine fuel nozzle wash system
in which existing gas turbine facilities may be used to be
modified with a simple construction so that, when fuel is
changed over to gas from oil, fuel nozzles are washed by water
and residual oil in the fuel nozzles is washed out, resulting
in contribution to cost reduction of the gas turbine plant.
In order to realize said objects, the present
invention provides means of following (1) to (5):
( 1 ) A gas turbine fuel system comprising a fuel oil
supply system for supplying fuel oil to a plurality of fuel
nozzles and a fuel gas supply system for supplying fuel gas to
said plurality of fuel nozzles so that gas turbine operation
may be done with fuel being changed over to either one of oil
and gas, characterized in further comprising a fuel oil
distribution control system for controlling flow rate and
pressure of fuel oil in each of fuel pipings connecting to said
fuel nozzles within a predetermined range by a control means
provided in said fuel oil supply system; a fuel oil purge system
provided close to said fuel nozzles in said fuel oil supply
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CA 02357492 2001-09-20
system for purging residual oil in said fuel oil supply system
and fuel nozzles by air; a purging air supply system for
supplying air to said fuel oil purge system; and a fuel nozzle
wash system for supplying wash water to upstream side of said
fuel nozzles in said fuel oil supply system connected to said
fuel nozzles.
In the invention of (1) above, the fuel oil
distribution control system causes fuel oil to flow into the
fuel oil supply system uniformly so that unbalance in the fuel
flow rate in each of the pipings is dissolved and the fuel oil
purge system purges effectively the residual oil in the fuel
oil supply system and fuel nozzles so that the problem of
pipings being blocked by carbonization of the fuel oil is
dissolved. Also, the purging air supply system supplies air
of appropriate temperature into the purge system so that air
supply to the purge system is ensured. Further, the fuel nozzle
wash system purges the residual oil by injecting water so that
reliability of purging the residual oil is enhanced. Said air
purge and water purge may be done by either of them being changed
over to one from the other as the case may be.
(2) A gas turbine fuel oil distribution control
system, characterized in that there are provided a series
control valve comprising a plurality of valves for controlling
pressure loss in a fuel oil supply system so as to correspond
to a plurality of fuel nozzles, each of said plurality of valves
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i
being driven controllably at same time with same opening; a
drive unit for driving said series control valve; and a control
unit for controlling said drive unit, and said control unit is
inputted with a system differential pressure signal and a load
signal of said fuel oil supply system to put out to said drive
unit a signal to throttle said series control valve
approximately to an intermediate opening while the system
differential pressure is a predetermined low differential
pressure and a signal to open said series control valve fully
for a predetermined time when said system differential pressure
comes to a predetermined high differential pressure.
In the gas turbine fuel oil distribution control
system of the invention of ( 2 ) above, while the series control
valve is controlled of the opening by the control unit and the
drive unit, the control unit is inputted with differential
pressure signal and load signal of the fuel oil supply system
or the fuel nozzles to put out to the drive unit a signal to
throttle the series control valve approximately to an
intermediate opening while the system differential pressure is
a predetermined low differential pressure during the time from
gas turbine ignition to rated speed arrival. In the high fuel
flow rate area, when the system differential pressure comes to
a predetermined high differential pressure, a signal to open
the series control valve fully is put out to the drive unit.
Thus, the differential pressure each of the fuel
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nozzles is set to a higher differential pressure than the
necessary nozzle differential pressure by the series control
valve and the gas turbine operation is done with the fuel oil
being so controlled that unbalance in the fuel flow rate as so
far occurred in the low fuel flow rate area is reduced, hence
the prior art flow divider becomes unnecessary and reliability
of the fuel oil distribution is enhanced.
(3) A gas turbine fuel oil purge system in a gas
turbine fuel oil supply system comprising a plurality of fuel
oil supply pipings for supplying fuel oil to a plurality of fuel
nozzles via a header; and a drain piping connected to said
plurality of fuel oil supply pipings, characterized in that
there are provided a sealing connection pipe close to said fuel
nozzles in each of said fuel oil supply pipings between said
header and fuel nozzles; and a purging air supply piping for
supplying air to each said sealing connection pipe, and each
said sealing connection pipe causes the air from said purging
air supply piping to flow toward said fuel nozzles as well as
to flow into said fuel oil supply pipings on the opposite side
of said fuel nozzles to be discharged from said drain piping.
In the gas turbine fuel oil purge system of the
invention of (3) above, the sealing connection pipe and the
purging air supply piping are provided close to the fuel nozzles
in each of the fuel oil supply pipings and air from the sealing
connection pipe is injected from each of the fuel nozzles so
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that the residual oil only in the very short piping between the
sealing connection pipe and each of the fuel nozzles is
discharged into the combustor. At the same time, the combustion
gas in the combustor is prevented from flowing reversely into
the fuel oil supply pipings by the air injected from the fuel
nozzles, hence the air so injected has a function of sealing
as well.
At the same time of said sealing function, the air
also flows from the sealing connection pipe into the fuel oil
supply pipings on the opposite side of the fuel nozzles and
after flowing through the fuel oil supply pipings and the drain
piping, it is discharged outside of the system. Hy this flow
of air, all the residual oil in the fuel oil supply pipings is
discharged outside of the system from the drain piping.
According to the invention of (3) above, therefore, when the
fuel is changed over to gas from oil and the residual oil in
the pipings is to be purged, the residual oil to be injected
into the combustor is only the residual oil in the very short
piping close to the fuel nozzles and other residual oil is
discharged outside of the system from the drain piping, hence
load change caused by burning of the residual oil is reduced.
(4) A gas turbine fuel nozzle purging air supply
system in a gas turbine air system for supplying air, extracted
from compressor outlet air and cooled at an air cooler, to a
rotor as rotor cooling air as well as for supplying air,
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diverging from said air extracted from compressor outlet air
and being elevated of pressure at a pressure elevation
compressor, to be used as fuel nozzle purging air,
characterized in that said air cooler comprises a first cooler
and a second cooler, air cooled at said first cooler is used
for said rotor cooling air and air diverging from the air cooled
at said first cooler is sent to said second cooler to be cooled
and then sent to said pressure elevation compressor.
In the gas turbine fuel nozzle purging air supply
system of the invention of ( 4 ) above, the air cooler comprises
the first and second coolers and the air cooled at the first
cooler is used as the rotor cooling air to be supplied for rotor
cooling. Further, a portion of the air cooled at the first
cooler diverges to enter the second cooler to be cooled again,
thus the compressor outlet air is cooled to a lower temperature
and is led into the pressure elevation compressor. When the
air is compressed to a higher pressure at the pressure elevation
compressor, its temperature also is elevated, but as the air
at the pressure elevation compressor inlet is cooled enough to
the lower temperature at the first and second coolers, even if
it is elevated of temperature, it can be used as the fuel nozzle
purging air without being cooled further.
In the prior art system, air extracted from the
compressor outlet air is cooled at a separate cooler and is led
into the pressure elevation compressor to be compressed and
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thus to be elevated of temperature. This air so elevated of
temperature is cooled again at another separate cooler to be
adjusted to a lower temperature which is appropriate for the
purging air. In the prior art system, therefore, separate
coolers are needed and large facilities and space therefor are
required. But in the invention of (4) above, the air cooler
for the rotor cooling air is made in two units which are used
for cooling the purging air as well, separate coolers are not
needed, facilities are simplified and cost reduction is
attained.
(5) A gas turbine fuel nozzle wash system in a gas
turbine wash system comprising a fuel oil supply system for
supplying fuel oil to fuel nozzles in a combustor; a compressor
wash water supply system for supplying wash water to a
compressor which supplies compressed air to said combustor; and
a wash water tank for supplying the wash water to said
compressor wash water supply system, characterized in that
there are provided a wash water by-pass piping and an
opening/closing valve between said fuel oil supply system and
compressor wash water supply system and when said opening/
closing valve is opened, the wash water is supplied to said fuel
nozzles from said wash water tank via said fuel oil supply
system to be injected from said fuel nozzles so that said fuel
nozzles are washable.
In the gas turbine fuel nozzle wash system of the
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invention of (5) above, the wash water by-pass piping and
the opening/closing valve are provided between the existing
fuel oil supply system and compressor outlet wash system so
that the wash water for compressor washing in the wash water
tank is led into the fuel oil supply system. When the fuel
is changed over to gas from oil, the oil remains in the fuel
nozzles and is carbonized to stick there, which results in a
fear of blockage of the fuel nozzles. Hence, when the fuel
is changed over to gas, wash water for the compressor
washing is led to the fuel nozzles via the wash water by-
pass piping and fuel oil supply system to be injected from
the fuel nozzles, thus the fuel nozzles are washed and fear
of blockage of the nozzles is cleared. Accordingly, the
existing pipings are made use of and wash water for the
compressor washing is used for nozzle washing as well,
thereby facilities cost is reduced and washing of the fuel
nozzles with simple structure becomes possible.
In one embodiment, the invention provides a gas turbine
fuel system comprising a fuel oil supply system for
supplying fuel oil to a plurality of fuel nozzles (X2) and a
fuel gas supply system for supplying fuel gas to said
plurality of fuel nozzles (X1) so that gas turbine operation
may be done with fuel being changed over to either one of
oil and gas, characterized in further comprising a fuel oil
distribution control system (A) for controlling flow rate
and pressure of fuel oil in each of fuel pipings connecting
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to said fuel nozzles (X2) within a predetermined range by a
control means provided in said fuel oil supply system; a
fuel oil purge system (B) provided upstream to said fuel
nozzles (X2) in said fuel oil supply system for purging
residual oil in said fuel oil supply system and fuel nozzles
(X2) by air; a purging air supply system (C) for supplying
air to said fuel oil purge system (B); and a fuel nozzle
wash system (D) for supplying wash water to upstream side of
said fuel nozzles (X2) in said fuel oil supply system
connected to said fuel nozzles (X2).
BRIEF DESCRIPTION OF THE DRAWINGS:
Fig. 1 is a block diagram of an entire gas turbine fuel
system comprising a fuel oil distribution control system, a
fuel oil purge system, a purging air supply system and a
fuel nozzle wash system of one embodiment according to the
present invention.
Fig. 2 is a diagrammatic view of the fuel oil
distribution control system of Fig. 1.
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Fig. 3 is a view showing relation between load
transition (fuel flow rate) and system differential pressure
in the fuel oil distribution control system of Fig. 1.
Fig. 4 is a diagrammatic view of the fuel oil purge
system of Fig. 1.
Fig. 5 is a diagrammatic view of the purging air
supply system of Fig. 1.
Fig. 6 is a diagrammatic view of the fuel nozzle wash
system of Fig. 1.
Fig. 7 is a diagrammatic view showing one application
example of the fuel nozzle wash system of Fig. 6.
Fig.. 8 is a diagrammatic view showing another
application example of the fuel nozzle wash system of Fig. 6.
Fig. 9 is a block diagram of an entire gas turbine
fuel system comprising a fuel oil supply system, a fuel oil
purge system, a purging air,supply system and a compressor
outlet wash system in the prior art.
Fig. 10 is a diagrammatic view of the fuel oil supply
system of Fig. 9.
Fig. 11 is a view showing relation between load
transition (fuel flow rate) and system differential pressure
in the fuel oil supply system of Fig. 9.
Fig. 12 is a diagrammatic view of the fuel oil purge
system of Fig. 9.
Fig. 13 is a diagrammatic view of the purging air
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i.
supply system of Fig. 9.
Fig. 14 is a diagrammatic view of the compressor
outlet wash system of Fig. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
Herebelow, description will be made concretely on
embodiments according to the present invention with reference
to figures . Fig. 1 is a block diagram of an entire gas turbine
fuel system comprising therein a fuel oil distribution control
system, a fuel oil purge system, a purging air supply system
and a fuel nozzle wash system of one embodiment according to
the present invention. Fig. 1 is a view of block diagram in
contrast with that in the prior art of Fig. 9.
In Fig. 1, there are provided in a combustor X a
plurality of fuel nozzles X1 and Xz, respectively, and like in
the prior art, fuel nozzles X1 and supplied with fuel gas from
a fuel gas supply system and fuel nozzles X2 are supplied with
fuel oil from a fuel oil supply system. Letter A designates
a fuel oil distribution control system, which corresponds to
the fuel oil supply system G of Fig. 9. Letter B designates
a fuel oil purge system, which corresponds to the fuel oil purge
system H of Fig. 9, letter C designates a purging air supply
system, which corresponds to the purging air supply system J
of Fig. 9, and letter D designates a fuel nozzle wash system,
which corresponds to the compressor outlet wash system K of
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CA 02357492 2001-09-20
.
Fig. 9. Letters E, F designates selector valves, respectively,
wherein in case of air purge, the valve E is opened and the valve
F is closed and in case of water purge, the valve E is closed
and the valve F is opened, reversely, and purging may be done
by either one of the air purge and the water purge or by
combination thereof in which the water purge is done first and
then the air purge is done.
Description will be made below on each of the
mentioned systems . Fig. 2 is a diagrammatic view of the fuel
oil distribution control system A of Fig. 1, which is a view
of the system in contrast with that in the prior art of Fig.
10. In Fig. 2, parts having same functions as those of the prior
art shown in Fig. 10 are given same reference letters or
numerals with description thereon being omitted and
characteristic portions of the present invention, that is,
portions 10 to 14, 20 and 21, will be described in detail.
In Fig. 2, numeral 13 designates a header and numeral
14 designates a plurality of pipings connecting to the header
13. Numeral 10 designates a series control valve, which has
a series of control valves in same number of pieces as that of
the fuel nozzles XZ so that each of the valves is controlled
at same time with same opening, that is, if the number of the
fuel nozzles X2 is 20 for example, the series control valve 10
is a 20 series control valve. While illustration of the
structure of the series control valve 10 is omitted, it is for
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CA 02357492 2001-09-20
example such that each of the valves is linked by a link
mechanism such as a cylinder and opening of the valves is
controlled simultaneously.
Numeral 21 designates a drive unit, which controls
opening of the series control valve 10 simultaneously, as
mentioned above, and comprises a hydraulic or pneumatic
cylinder or an electromotive cylinder or the like. Numeral 20
designates a control unit, which puts out an output signal to
the drive unit 21 so that opening of the series control valve
10 may be controlled, as described later.
In the construction as mentioned above, fuel oil
passes through a flow control valve 11 and a piping 12 to be
led into the header 13 and is then supplied into the respective
pipings 14 whose number of pieces is same as that of the fuel
nozzles X2. The respective pipings 14 connect to the respective
valves of the series control valve 10 and the fuel oil is
supplied through the series control valve 10 and pipings
15 to the respective fuel nozzles XZ for combustion in the
combustor X.
The series control valve 10 is controlled of the valve
opening via the drive unit 21 by signal from the control unit
20, as described later, such that while a nozzle differential
pressure is low, the opening is throttled to an intermediate
opening and when the nozzle differential pressure increases in
a high fuel flow rate area, the valve is opened fully to make
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CA 02357492 2001-09-20
flow resistance smaller, thus unusual elevation of the system
differential pressure is prevented.
Fig. 3 is a view showing relation between load
transition (fuel flow rate) and the system differential
pressure in the fuel oil distribution control system A of
Fig. 2. In Fig. 3, while the system differential pressure is
lower than the necessary nozzle differential pressure v1 from
time to when the gas turbine is ignited to time t1 when it
arrives at rated speed ( no load ) , the series control valve 10
is throttled to an intermediate opening so that the system
differential pressure is elevated higher than the necessary
nozzle differential pressure V1, which is shown by broken line
in Fig. 3, as fuel flow rate increases.
. At the time t1, the system differential pressure
arrives at differential pressure v2 beyond which there may
occur an unusually large differential pressure. Then, the
series control valve 10 is opened fully to make flow resistance
smaller and the system differential pressure is reduced rapidly.
Then, at time t1', the series control valve 10 is throttled
again to an intermediate opening. After the time t1', the
system differential pressure goes up again as the fuel flow rate
increases and when it arrives at V2, the series control valve
10 is opened fully again and thereafter same is repeated so that
control is done.
The system differential pressures V1, VZ are set in
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CA 02357492 2001-09-20
the control unit 20 to be stored and when the control unit 20
is inputted with gas turbine load signal and system
differential pressure signal, it checks the respective system
differential pressures at times to, t1 and t1' in the load
transition and when the ignition is done at to, signal to
throttle the opening of the series control valve 10 is put out
to the drive unit 21 so that the opening of the series control
valve 10 is throttled to an intermediate level and when the
system differential pressure comes to VZ, signal to open the
series control valve 10 fully is put out to the drive unit 21
so that the valve is opened completely and same control is
repeated thereafter.
According to the fuel oil distribution control system
A as described above, opening of the series control valve 10
is controlled by the control unit 20 and the drive unit 21 so
that while the system differential pressure is low for the time
of low load after the ignition, opening of the series control
valve 10 is throttled to elevate the system differential
pressure and unbalance in the fuel flow rate due to head
difference of the fuel nozzles is dissolved thereby and in the
high fuel flow rate area, the valve is opened fully and unusual
elevation of the system differential pressure is prevented
thereby. Thus, there is needed no such a flow divider as in
the prior art, fuel oil flow unbalance between each of the fuel
nozzles is prevented securely and reliability is enhanced.
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CA 02357492 2001-09-20
Next, the fuel oil purge system B will be described
with reference to Fig. 4. In Fig. 4, parts shown by reference
numerals or letters 1 to 4, 11 to 14, 23, X, X1 and XZ are same
as those in the prior art shown in Fig. 12 with description
thereon being omitted and characteristic portions of the
present invention, that is, parts shown by reference numerals
30 to 33, will be described in detail.
In Fig. 4, numeral 30 designates a purging air system
piping, numeral 31 designates an opening/closing valve,
numeral 32 designates a plurality of sealing connection pipes
and numeral 33 designates a plurality of pipings . Each of the
pipings 33 connects at its one end to each of the fuel nozzles
XZ and at its the other end to each of the sealing connection
pipes 32 and length of each of the pipings 33 is made as shorter
as possible preferably. Also, each of the sealing connection
pipes 32 is a T type connection pipe which comprises ports
connecting to the pipings 14 and 33 and the purging air system
piping 30, respectively.
Thus, the purging air system piping 30 is connected
closer to the fuel nozzles X2, as compared with the prior art
purging air system piping 26, between the header 13 and the fuel
nozzles XZ, hence residual oil in the pipings to be discharged
into the combustor X is reduced, as described later.
In the fuel oil purge system B constructed as above,
while operation is done by fuel oil, the fuel oil passes through
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CA 02357492 2001-09-20
the flow control valve 11 and the piping 12 to enter the header
13 and is distributed there to flow through the plurality of
pipings 14 and the sealing connection pipes 32 to be then
supplied into the plurality of fuel nozzles X2 via the pipings
33 and is injected into the combustor X for combustion.
When operation is to be done with the fuel being
changed over to gas from oil, the flow control valve ll~is closed
and fuel gas is supplied instead through the flow control valve
1, piping 2, fuel gas distributor 3 and piping 4 to enter the
respective fuel nozzles X1 to be burned in the combustor X. In
this case, there remains the previous fuel oil in the piping
12, header 13, piping 14 and piping 33 and if this remaining
fuel oil is left there as it is, it is carbonized to stick there,
thus when the fuel oil has been stopped to be changed over to
fuel gas, it is necessary to purge the remaining fuel oil while
operation is being done by the fuel gas.
In case of the purging, the opening/closing valve 31
is opened first so that purging air 41 is led into the purging
air system piping 30 to flow through one end each of the sealing
connection pipes 32 and the piping 33 to enter the fuel nozzles
XZ and is then injected into the combustor X from the fuel
nozzles to be burned. At same time, the purging air 41 is also
flown into the piping 14 through the other end each of the
sealing connection pipes 32.
Further, the opening/closing valve 24 is also opened
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CA 02357492 2001-09-20
to communicate with the drain valve piping 23. Thus, the
purging air 4I passes through the purging air system 30, sealing
connection pipes 32 and pipings 14 and further through the
header 13, piping 12, opening/closing valve 24 and drain valve
piping 23 and is discharged outside. Hy said flow of the purging
air 41, the fuel oil remaining in the pipings 33 is discharged
into the combustor X and the fuel oil remaining in the pipings
14, header 13 and piping 12 on the opposite side is discharged
outside of the system via the drain valve piping 23.
When the purging of the residual oil is to be done
while the operation is being done with fuel gas, as the purging
air 41 from the purging air system piping 30 flows through said
one end each of the sealing connection pipes 32 toward the
combustor X to be injected from the fuel nozzles Xz, the purging
air 41 has a sealing function to prevent reverse flow of the
combustion gas from the combustor X and in addition to this
sealing function, the purging air 41 causes the residual oil
in the pipings 14, header 13 and piping 12 on the opposite side
of the sealing connection pipes 32 to be discharged outside of
the system from the drain valve piping 23.
In the prior art case shown in Fig. 12, if the
opening/closing valve 24 of the drain valve piping 23 is opened
during the operation, there may arise a case that the combustion
gas from the combustor X is sucked to flow reversely through
the pipings 14, header 13 and piping 12 so that the residual
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CA 02357492 2001-09-20
oil in the pipings may burn by the high temperature combustion
gas to damage the pipings, but in the system of the present
invention, the purging air 41 is flown from the sealing
connection pipes 32 toward the combustor X to be injected from
the fuel nozzles Xz so as to seal the combustion gas, thus the
shortcomings in the prior art is prevented.
According to the fuel oil purge system B as described
above, the construction is made such that the purging air system
piping 30 and the sealing connection pipes 32 are connected
closer to the fuel nozzles X2 between the pipings 14 and the
fuel nozzles XZ and the purging air 41 having the sealing
function as well is injected from the fuel nozzles XZ so that
the residual oil in the pipings 33 is discharged as well as the
combustion gas from the combustor X is prevented from flowing
reversely into the pipings 14 side.
Further, the purging air 41 from the sealing
connection pipes 32 is flown through the pipings 14, header 13
and piping 12 to be discharged from the drain valve piping 23
so that the residual oil in these pipings is discharged outside
of the system from the drain valve piping 23, thus when the fuel
is changed over to gas from oil and residual oil in the pipings
is to be purged, the residual oil to be discharged into the
combustor X is only that remaining in the short pipings 33,
thereby load change caused by combustion of the residual oil
is reduced and a large load change is prevented.
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CA 02357492 2001-09-20
Next, the purging air supply system C will be
described with reference to Fig. 5. In Fig. 5, parts shown by
reference numerals 110, 42, 43, 48 and 53 are same as those in
the prior art shown in Fig. 13 with description thereon being
omitted and characteristic portions of the present invention,
that is, air coolers shown by reference numerals 50, 51 and
pipings thereof as well as simplified system accompanied
therewith, will be described in detail.
In Fig. 5, numeral 50 designates a first air cooler
and numeral 51 designates a second air cooler. Both of the air
coolers 50, 51 are cooled by air sent from a fan 45 driven by
a motor 44. In these air coolers 50, 51, compressor outlet air
is led into the first air cooler 50 via the piping 42 and the
aid after cooled is led from outlet of the first air cooler 50
into the gas turbine 110 as rotor cooling air via the piping
43. At same time, a portion of the air at the outlet of the
first air cooler 50 is extracted to be led into the second air
cooler 51 via a piping 49.
The air cooled at the second air cooler 51 is led into
a drain separator 52 via a piping 46 to be removed of drain and
is then led into the pressure elevation compressor 53 via a
piping 47 to be elevated of pressure and thereby to be heated
to an appropriate temperature as purging air. Thus, this air
is supplied as fuel nozzle purging air via the piping 48.
In the purging air supply system C constructed as
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CA 02357492 2001-09-20
above, the compressor outlet air is of about 400°C and is led
into the first air cooler 50 via the piping 42 to be cooled to
about 200 to 250°C by air sent from the fan 45 and is then
supplied into the .gas turbine 110 as the rotor cooling air like
in the prior art.
The air cooled at the first air cooler 50 is of about
200 to 250°C and a portion thereof diverges into the piping 49
to enter the second air cooler 51. The air entering the second
air cooler 51 is cooled, like in the first air cooler 50, by
air from the fan 45 driven by the motor 44. The air so cooled
is of about 60 to 80°C and is led into the drain separator 52
via the piping 46 to be removed of drain and then enters the
pressure elevation compressor 53 via the piping 47 to be
elevated of pressure and thereby to be elevated of temperature
to about 100 to 130°C. This air of about 100 to 130°C is
supplied
to be used as the fuel nozzle purging air via the piping 48.
According to the purging air supply system C
described above, the air cooler for obtaining the rotor cooling
air is constructed in two units of the first air cooler 50 and
the second air cooler 51 and the compressor outlet air of about
400°C is cooled to about 200 to 250°C at the first air cooler
50 to be used as the rotor cooling air. At the second air cooler
51, the air so cooled to about 200 to 250°C is further cooled
to about 60 to 80°C.
The air so cooled to about 60 to 80°C is used as inlet
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CA 02357492 2001-09-20
air of the pressure elevation compressor, hence the air after
elevated of pressure is of temperature of about 100 to 130°C
which is appropriate as the fuel nozzle purging air. In the
prior art case as shown in Fig. 13, the air entering the pressure
elevation compressor 53, which is the compressor outlet air,
is of a high temperature of about 400°C, hence it is cooled as
first step to about 130°C at the cooler 94 and it is~elevated
of pressure at the pressure elevation compressor 53. But this
air is thereby elevated of temperature to about 200°C, hence
it is cooled again at the cooler 100 for obtaining air of about
150°C.
For this purpose, there are needed the coolers 94,
100 which are large facilities . But in the purging air supply
system C of the present invention, the air cooler is made in
two units of the first air cooler 50 for obtaining the rotor
cooling air and the second air cooler 51 for obtaining the fuel
nozzle purging air, thereby the coolers 94, 100 become
unnecessary, which results in simplification of facilities,
reduction of installation space and reduction of cost.
Finally, the fuel nozzle wash system D will be
described with reference to Figs . 6 to 8 . In Figs . 6 to 8, same
parts as those in the prior art shown in Fig. 14 are given same
reference numerals or letters with description thereon being
omitted and characteristic portions of the present invention,
that is, portions shown by reference numerals 71 to 75, will
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CA 02357492 2001-09-20
be described in detail.
In Fig. 6, numeral 71 designates a by-pass piping,
which connects to the upstream side of the opening/closing
valve 63 so that wash water from the wash tank 62 flows
therethrough to by-pass. Numeral 72 designates an
opening/closing valve and numeral 73 designates a header for
distributing the wash water. Numeral 74 designates a~plurality
of wash water supply pipings and numeral 75 designates a
plurality of connection pipes which are connected to the
respective fuel supply pipings 14.
The wash water led from the wash water tank 62 into
the header 73 via the by-pass piping 71 is distributed to flow
into the respective wash water supply pipings 74 and to further
flow into the respective fuel supply pipings 14 via the
connection pipes 75 and then enters the respective fuel nozzles
XZ.
In the fuel nozzle wash system D constructed as above,
when the fuel nozzles XZ are to be washed, the flow control valve
11 is closed, the opening/closing valve 63 is also closed, the
opening/closing valve 72 is opened and the air control valve
60 is opened. Thus, high pressure air is led into the wash water
tank 62 to pressurize the wash water in the tank so that the
wash water is led into the header 13.
The wash water is distributed at the header 13 to flow
into the respective wash water supply pipings and further to
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CA 02357492 2001-09-20
flow into the respective fuel supply pipings 14 via the
connection pipes 75 and is then injected into the combustor X
from the respective fuel nozzles so that residual oil in the
fuel nozzles Xz is washed and removed. The water containing
the residual oil injected from the fuel nozzles X2 is so
discharged into the combustor X and is vaporized by the high
temperature there. -
Fig. 7 is a diagrammatic view showing one application
example of the fuel nozzle wash system D of the present
invention. In Fig. 7, what is different from that shown in Fig.
6 is that the by-pass piping does not diverge from the piping
64 of the compressor wash system but is connected directly to
the wash water tank 62 and the opening/closing valve 72 is
provided in this by-pass piping 67, so that the fuel nozzle wash
system is made in a separate system from the compressor wash
system. Construction of other portions of Fig. 7 is same as
that of Fig. 6. In the application example shown in Fig. 7 also,
same function and effect of the invention as those of the wash
system shown in Fig. 6 can be obtained.
Fig. 8 is a diagrammatic view showing another
application example of the fuel nozzle wash system D of the
present invention. In Fig. 8, what is different from that shown
in Fig. 6 is that the by-pass piping is connected to the
downstream side of the opening/closing valve 63 of the
compressor wash system. In this system of Fig. 8, the
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CA 02357492 2001-09-20
compressor wash system and the fuel nozzle wash system are
operated at same time by the single opening/closing valve.63,
wherein the opening/closing valve 72 shown in Figs . 6 and 7 is
eliminated. Construction of other portions of Fig. 8 is same
as that of Figs . 6 and 7 . In the application example shown in
Fig. 8 also, same function and effect of the invention as those
of the wash system shown in Figs. 6 and 7 can be obtained.
According to the fuel nozzle wash systems D shown in
Figs. 6 and 7, the construction is made such that there are
provided the by-pass pipings 71, 67 for flowing therethrough
the wash water from the wash water tank 62 of the compressor
outlet wash system to by-pass and the wash water flows through
the header 73, wash water supply pipings 74 and connection pipes
75 to the respective fuel supply pipings 14 and is then supplied
into the fuel nozzles Xz for washing the residual oil in the
fuel nozzles Xz. Also, according to the fuel nozzle wash system
D shown in Fig. 8, the construction is made such that the piping
64 of the compressor outlet wash system and the piping 68 of
the fuel nozzle wash system are connected to the wash water tank
62 via the single opening/closing valve 63. Thus, by these
constructions, washing of the fuel nozzles XZ can be done by
the wash water from the wash water tank 62 of the compressor
outlet wash system and there is needed no exclusive wash
apparatus of the fuel nozzles XZ, hence the wash system can be
made in a simple piping structure, which contributes to cost
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CA 02357492 2001-09-20
reduction of the gas turbine plant.
It is understood that the invention is not limited
to the particular construction and arrangement herein
illustrated and described but embraces such modified forms
thereof as come within the scope of the appended claims.
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