JP4335409B2 - Gas turbine fuel supply system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel supply apparatus for a gas turbine having a steam cooling system for cooling a combustor using steam.
[0002]
[Prior art]
In recent years, as a gas turbine combustor, for example, a steam-cooled combustor that can achieve low NO _x even with a 1500 ° C. class gas turbine has attracted attention. That is, by cooling the combustor wall surface with steam, the air previously used for wall surface cooling is used for combustion, so that the premixed combustion temperature can be set to the air-cooled combustor despite the high temperature of the gas turbine. it is the low NO _X reduction is possible by suppressing the tears.
[0003]
For example, as shown in FIG. 3, such steam cooling forms a premixed gas of main fuel and combustion air around the cone 1 where the pilot fuel and combustion air react to form a diffusion flame. -It is employ | adopted for cooling of the tail cylinder 4 of the multi-nozzle type premix type combustor 3 which divides and arrange | positions the premixed flame formation nozzle 2 to eject.
[0004]
According to this, the cooling steam is first supplied to the longitudinal intermediate portion (see the manifold 6b) of the tail cylinder 4 by a cooling jacket (not shown) formed on the wall surface of the tail cylinder 4 and the manifolds 6a, 6b, 6c. From here, as shown by the arrows in the figure, the gas flow is divided into the upstream side and the downstream side to cool the wall surface, and then recovered from the inlet part (see the manifold 6a) and outlet part (see the manifold 6c) of the tail cylinder 4. It is like that.
[0005]
[Problems to be solved by the invention]
By the way, in a gas turbine having a steam-cooled combustor as described above, the steam (cooling) system including the combustor is warmed before startup, and damage to piping and the like due to increased thermal stress at startup Is avoided in advance.
[0006]
However, even at the time of the warm pipe, the leakage of steam at the connection part inside the gas turbine main body of the steam (cooling) system cannot be completely eliminated. Therefore, the steam leaked into the gas turbine main body passes through the combustion air supply passage (see the arrow in FIG. 3) and the like, and also from the fuel nozzle for the pilot fuel and the main fuel to the fuel manifold for the pilot fuel and the main fuel. Intrusion and condensation will occur.
[0007]
As a result, when the gas turbine is started, a part of the branch pipe from the fuel manifold to the fuel nozzle is partially blocked by water (condensed steam), and the fuel cannot be supplied sufficiently. Cannot be obtained, and as a result, the gas turbine cannot be started.
[0008]
The present invention has been made in view of the above-described situation, and reliably prevents leakage steam from entering the fuel manifold from the fuel nozzle during the warm pipe, thereby improving the reliability of the gas turbine plant. An object is to provide a fuel supply device.
[0009]
[Means for Solving the Problems]
In order to achieve such an object, a fuel supply apparatus for a gas turbine according to the present invention includes a fuel for supplying fuel to a fuel nozzle of the combustor in a gas turbine having a steam cooling system for cooling the combustor using steam. A gas supply system for preventing steam intrusion is connected to the supply system via a flow control valve, and the steam intrusion preventing gas is allowed to flow out from the fuel nozzle during warm pipes of the steam cooling system before starting the gas turbine. Features.
[0010]
Further, control air from a control air system provided for performing a separate nozzle purge is used as the vapor intrusion prevention gas.
[0011]
Further, nitrogen gas from a nitrogen gas supply system is used as the vapor intrusion prevention gas.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, a fuel supply apparatus for a gas turbine according to the present invention will be described in detail with reference to the drawings by way of examples.
[0013]
[First embodiment]
FIG. 1 is a system diagram of a fuel supply system of a gas turbine showing a first embodiment of the present invention. Note that the description of the steam cooling system of the combustor is omitted with reference to FIG.
[0014]
As shown in FIG. 1, a fuel such as a liquid from a fuel supply source (not shown) is supplied to a main fuel manifold through a main fuel passage 10, from which each multi-nozzle type premix combustor 3 (see FIG. 3). ) Are distributed and supplied to a plurality of main fuel nozzles. The main fuel passage 10 is provided with a fuel cutoff valve 11, a main fuel pressure adjustment valve 12, and a main fuel flow rate adjustment valve 13, which are hydraulic control valves in order from the upstream side.
[0015]
Further, the fuel is supplied to the pilot fuel manifold through a pilot fuel passage 14 branched from the main fuel passage 10 between the fuel cutoff valve 11 and the main fuel pressure control valve 12, and from here, each multi-nozzle type premix is supplied. The fuel is distributed and supplied to the pilot fuel nozzles of the combustor 3. The pilot fuel passage 14 is provided with a pilot fuel pressure control valve 15 and a pilot fuel flow rate control valve 16 each consisting of a hydraulic control valve in order from the upstream side. A fuel escape passage 17 is branched from the main fuel passage 10 immediately after the fuel cutoff valve 11 (downstream), and the operation of the gas turbine is stopped by a fuel relief valve 18 comprising a hydraulic control valve interposed in the fuel release passage 17. Sometimes fuel is released to the atmosphere.
[0016]
In this embodiment, in the oil-fired gas turbine combustor, the control air from the control air system for permanent nozzle purge passes through the main air passage 19 connected to the main fuel passage 10 downstream of the main fuel flow control valve 13. To the main fuel manifold, and from here to a plurality of main fuel nozzles of each multi-nozzle type premix combustor 3. In the main air passage 19, a nozzle purge air shut-off valve 20 comprising a pneumatic control valve and a nozzle purge air flow rate regulating valve 21 comprising a manual needle valve are interposed in order from the upstream side.
[0017]
Further, it branches from a main air passage 19 between the nozzle purge air shut-off valve 20 and the nozzle purge air flow control valve 21 and passes through a sub air passage 22 connected to a pilot fuel passage 14 downstream of the pilot fuel flow control valve 16. Thus, the control air is supplied to the pilot fuel manifold, and is distributed and supplied to the pilot fuel nozzles of the multi-nozzle type premix combustors 3 from here. The sub air passage 22 is provided with a nozzle purge air flow rate adjusting valve 23 comprising a manual needle valve.
[0018]
The nozzle purge air shut-off valve 20 is automatically or manually opened by a signal from a controller (not shown) at the time of warm pipe of the steam cooling system (see FIG. 3) before the gas turbine is started. The control valves 21 and 23 are set to a minute opening.
[0019]
With this configuration, the fuel cutoff valve 11 is closed (the main fuel pressure adjustment valve 12, the main fuel flow rate adjustment valve 13, the pilot fuel pressure adjustment valve 15 and the pilot fuel flow rate adjustment valve 16 are also closed), and the main When the steam cooling system is warmed before the gas turbine is started and the fuel supply to the fuel nozzle and the pilot fuel nozzle is stopped, the nozzle purge air shutoff valve 20 is opened and the nozzle purge air flow rate control valves 21 and 23 are slightly opened. Set to degrees.
[0020]
Thus, at this time, the control air from the control air system for nozzle purging is supplied to the main fuel manifold through the main fuel passage 10 and is supplied to the pilot fuel manifold through the pilot fuel passage 14. And control air is discharged from the pilot fuel nozzle.
[0021]
As a result, the steam leaked from the steam cooling system does not enter the main fuel manifold and the pilot fuel manifold side from the main fuel nozzle and the pilot fuel nozzle, and the main fuel nozzle and the pilot fuel are caused by the condensation of the intruding steam as described above. Blocking a part of the branch pipe connecting the nozzle, the main fuel manifold, and the pilot fuel manifold is avoided in advance.
[0022]
Further, in this embodiment, control air from the existing nozzle purge control air system is used as the gas for preventing vapor intrusion, so that cost reduction and space saving can be achieved compared to the case where a separate dedicated gas supply system is provided. I can plan.
[0023]
[Second Embodiment]
FIG. 2 is a system diagram of a fuel supply system of a gas turbine showing a second embodiment of the present invention.
[0024]
This is because, in place of the control air from the control air system for nozzle purge in the first embodiment, when the steam cooling system is warmed before the gas turbine is started, in the gas turbine combustor of the gas fuel, nitrogen that is permanently installed for safety is used. Nitrogen gas from the gas supply system is supplied to the main fuel passage 10 and the pilot fuel passage 14 immediately upstream (upstream) of the main fuel flow control valve 13 and the pilot fuel flow control valve 16, respectively.
[0025]
According to this, the same operation and effect as in the first embodiment can be obtained except that the main fuel flow rate adjusting valve 13 and the pilot fuel flow rate adjusting valve 16 are set to a very small opening during the warm pipe.
[0026]
The present invention is not limited to the above-described embodiments, and within a range that does not depart from the gist of the present invention, it is possible to change the supply location of nitrogen gas or control air in consideration of the flow rate control valve or to prevent vapor intrusion. It goes without saying that various modifications such as using other gases are possible.
[0027]
【The invention's effect】
As described above in detail based on the embodiments, the invention according to claim 1 of the present invention is directed to a fuel nozzle of the combustor in a gas turbine having a steam cooling system for cooling the combustor using steam. A gas supply system for preventing steam intrusion is connected to a fuel supply system for supplying fuel via a flow rate control valve, and the gas for preventing steam intrusion is supplied from the fuel nozzle during warm-up of the steam cooling system before starting the gas turbine. Therefore, it is possible to reliably prevent the leaked steam from entering the fuel manifold from the fuel nozzle during the warm pipe, thereby improving the reliability of the gas turbine plant.
[0028]
The invention according to claim 2 of the present invention is characterized by using control air from a control air system provided to perform nozzle purge separately as the vapor intrusion prevention gas. In addition to the same effect, the oil-fired gas turbine combustor uses control air from a permanent nozzle purge control air system, which reduces costs and saves space compared to providing a separate dedicated gas supply system. I can plan.
[0029]
The invention according to claim 3 of the present invention is characterized in that nitrogen gas from a nitrogen gas supply system is used as the gas for preventing vapor intrusion. Therefore, in addition to the same effect as that of the invention according to claim 1, gas Since the fuel gas turbine combustor uses nitrogen gas from a permanent nitrogen gas supply system, cost reduction and space saving can be achieved as compared with a case where a separate dedicated gas supply system is provided.
[Brief description of the drawings]
FIG. 1 is a system diagram of a fuel supply system of a gas turbine showing a first embodiment of the present invention.
FIG. 2 is a system diagram of a fuel supply system of a gas turbine showing a second embodiment of the present invention.
FIG. 3 is a side sectional view around a gas turbine combustor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cone 2 Premixed flame formation nozzle 3 Multi-nozzle type premixed combustor 4 Cylinder 6a, 6b, 6c Manifold 10 Main fuel passage 11 Fuel shut-off valve 12 Main fuel pressure control valve 13 Main fuel flow control valve 14 Pilot fuel passage 15 Pilot fuel pressure control valve 16 Pilot fuel flow control valve 17 Fuel escape passage 18 Fuel relief valve 19 Main air passage 20 Nozzle purge air shut-off valve 21 Nozzle purge air flow control valve 22 Sub air passage 23 Nozzle purge air flow control valve

Claims (3)

  In a gas turbine having a steam cooling system for cooling a combustor using steam, a gas supply system for preventing steam intrusion is connected to a fuel supply system for supplying fuel to a fuel nozzle of the combustor via a flow control valve. A gas turbine fuel supply apparatus for causing the steam intrusion prevention gas to flow out of the fuel nozzle during warm-up of the steam cooling system before starting the gas turbine. 2. The fuel supply apparatus for a gas turbine according to claim 1, wherein control air from a control air system provided for performing a separate nozzle purge is used as the vapor intrusion prevention gas.   2. The fuel supply apparatus for a gas turbine according to claim 1, wherein nitrogen gas from a nitrogen gas supply system is used as the vapor intrusion prevention gas.

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