Arrangement for sealing a steam-cooled gas turbine

Details Arrangement for sealing a steam-cooled gas turbine Arrangement for sealing a steam-cooled gas turbine

2000-09-29

2003-02-25

Verdier, Christopher (Department: 3745)

Rotary kinetic fluid motors or pumps

With changing state confined heat exchange mass

C415S116000, C416S09600A, C403S335000, C403S359100, C277S630000, C277S637000

Reexamination Certificate

active

06524061

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a steam-cooled gas turbine and, in particular, to an arrangement for sealing spindle bolts of a steam-cooled gas turbine.
2. Description of the Related Art
In order to improve the efficiency of a gas turbine, the temperature of the combustion gas at the inlet of the gas turbine has recently been increased to 1,500 degrees Celsius. In order to protect the stator and the blades from the high temperature combustion gas, a so-called steam-cooled gas turbine, in which these elements are cooled by relatively low temperature steam, is under development. In such a steam-cooled gas turbine, steam is supplied from a steam source such as, for example, a steam extracting pipe in a steam turbine in a combined cycle or in an auxiliary boiler. In particular, the steam for cooling the blades of a gas turbine is supplied from a steam source through a steam passage formed to extend through the rotor to the respective blades fixed to the rotor.
The steam passage includes a plurality of steam supply passages longitudinally extending in the rotor from its tail end, an annular steam supply chamber, which is fluidicly connected to the plurality of steam supply passages, for distributing the steam equally to the respective blades, a steam recovery chamber for receiving the steam equally from the blades, and a plurality of steam recovery passages for directing steam from steam recovery chambers to the outside of the steam-cooled gas turbine.
FIG. 14
is a partial section of a rotor of a steam-cooled gas turbine according to a prior art turbine and shows first and second rotor disks
110
and
120
of a rotor
100
. The disks
110
and
120
include a plurality of longitudinally extending spindle bolt holes
112
and
122
which are circumferentially arranged at intervals. The first and second rotor disks
110
and
120
are connected together with the other rotor disks (not shown) of the gas turbine by spindle bolts
102
inserted through the holes
112
and
122
so as to provide the integral rotating rotor
100
of the steam-cooled gas turbine.
The first and second rotor disks
110
and
120
further include a plurality of steam passages
114
and
124
, circumferentially arranged at intervals, for supplying and recovering the steam for cooling the blades. The steam passages
114
and
124
are disposed in the peripheral portions of the rotor disks
110
and
120
radially outside of the holes
112
and
122
. A plurality of steam supply conduits
104
, which provide a steam supply passage for supplying the steam to the blades, and a plurality of steam recovery conduits
106
, which provide a steam recovery passage for directing the steam used for cooling the blades to the outside of the steam-cooled gas turbine, are circumferentially alternatively provided in the steam passages
114
and
124
.
A steam supply chamber
130
, for equally distributing the steam to the primary blades (not shown), which are attached to the first rotor disk
110
, is formed in the axially outer end face of the first rotor disk
110
. A steam recovery chamber
132
, for equally receiving the steam used for cooling the primary and secondary blades, is formed between the first and second rotor disks
110
and
120
. Likewise, a steam supply chamber
134
for equally distributing the steam to the secondary blades is formed between the second rotor disk
120
and a third rotor disk (not shown).
In general, extracted steam from a low pressure steam turbine is used as cooling steam. The steam is supplied to the steam supply conduits
104
, from which the steam is further supplied to the primary and secondary blades through the steam supply chambers
130
and
134
. The steam used for cooling the primary and secondary blades is received by the steam recovery chamber
132
from which the steam is directed to the outside of the steam-cooled gas turbine through the steam recovery conduits
106
.
The spindle bolt holes
112
and
124
have a diameter which is larger than the outer diameter of the spindle bolts to ensure the workability of assembly of the rotor by connecting the rotor discs to each other by spindle bolts. Therefore, relatively large gaps result between the spindle bolt holes and the spindle bolts. On the other hand, the steam recovery chambers
132
and
134
which are formed in the rotor are fluidly connected to the spindle bolt holes
112
and
122
so that steam leaks through the gaps between the first and second rotor discs
110
and
120
and the spindle bolts
102
result. The steam leakage through the gaps between the secondary rotor disc
120
and the spindle bolts
102
flows into the steam recovery chamber
132
so that it can be recovered through the steam recovery conduits
106
. However, the steam leakage through the gaps between the first rotor disc
110
and the spindle bolts
102
cannot be recovered, which decreases the overall efficiency of a plant which utilizes the steam-cooled gas turbine.
In order to reduce the steam leakage through the gaps between the first rotor disc
110
and the spindle bolts
102
, in the prior art, for example Japanese Unexamined Patent Publication No. 11-50803, annular sealing members
140
, as shown in
FIGS. 14 and 15
, are provided. Snap rings
142
are used as a fastener for securing the sealing members
140
to the first rotor disk
110
. The snap rings
142
are fitted in grooves
116
which are formed in the first rotor disc
110
. When the rotor rotates, the centrifugal force applied thereto results in deformations in the respective snap rings
142
, which in particular reduces the diameter of the snap rings
142
, which may result in detachment of the snap rings
142
from the grooves
116
.
As shown in
FIG. 14
, the steam supply chamber
130
is provided at one of the ends of the rotor
100
, which end is disposed in the central portion of the steam-cooled gas turbine. The steam leakage from the steam supply chamber
130
may result in a problem of condensation around the bearings in the central portion of the steam-cooled gas turbine. Therefore, a severe sealing arrangement around the steam supply chamber
130
is required. Further, in order to allow inspection or the execution of maintenance in the steam supply chamber
130
, a simple sealing arrangement is desired.
SUMMARY OF THE INVENTION
The invention is directed to solve the prior art problems, and to provide a steam-cooled gas turbine improved to prevent the detachment of the fastener.
Another objective of the invention is to provide an arrangement for sealing or reducing the steam leakage through the gap between the first rotor disk and the spindle bolts, which arrangement is improved to prevent the detachment of the fastener for securing the sealing members to the first rotor disk.
Another objective of the invention is to provide a method of assembling such steam-cooled gas turbine.
Another objective of the invention is to provide a steam-cooled gas turbine which includes a steam chamber closed by a closure which can be assembled easily.
The invention provides a steam-cooled gas turbine with a plurality of blades cooled by steam supplied from an external steam source. The steam-cooled gas turbine has a rotor for supporting the blades. The rotor is composed of a plurality of rotor disks which includes a plurality of spindle bolt holes circumferentially arranged at intervals and spindle bolts extending through the spindle bolt holes to connect the plurality of rotor disks to each other to define the rotor. The rotor includes a steam supply passage extending in the rotor, a steam supply chamber, fluidly connected to the steam supply passage and the respective blades, for distributing the steam to the respective blades from the steam source through the steam supply passage, a steam recovery chamber, fluidly connected to the respective blades, for equally receiving the steam used for cooling the blades, and a steam recovery passage, fluidly connected to the steam recovery chamber, for directing the steam from the steam recovery

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