Power plants – Combustion products used as motive fluid – Multiple fluid-operated motors
Reexamination Certificate
1998-11-23
2002-04-09
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
Multiple fluid-operated motors
C060S039300, C060S039780
Reexamination Certificate
active
06367242
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recovery type steam cooled gas turbine, and more particularly to a recovery type steam cooled gas turbine for warming steam cooling passages of combustor walls, moving blades, stationary blades, a rotor or the like upon starting the gas turbine, for preventing dew formation when feeding the steam, and for preventing rust generated by the condensed steam during the stopping operation.
2. Description of the Related Art
Recently, the combustion temperature of combustion gas for gas turbine has been increasing in accordance with demands for higher efficiency in power generation plants. Consequently, high temperature exhaust gas from a gas turbine is introduced into a waste heat recovery boiler and the exhaust gas heats the boiler to generate steam. Moreover, a composite power generation plant driven by a steam turbine using this steam has been developed. In such a composite power generation plant, a steam cooling method with superior cooling performance has been proposed for cooling high temperature components of the gas turbine instead of using an air cooling method.
FIG. 8
shows one example of the above-described steam cooled type gas turbine, and in particular shows an operation method when starting. In
FIG. 8
, numeral
70
denotes the gas turbine, numerals
71
-
1
,
71
-
2
and
71
-
3
denote stationary blades, numerals
72
-
1
,
72
-
2
and
72
-
3
denote moving blades, and numeral
73
denotes a rotor of the gas turbine
70
. Numerals
74
,
75
,
76
and
77
denote three-way valves, respectively. Numeral
80
denotes a steam feed pipe. Numeral
81
denotes an air feed pipe for introducing cooling air from a compressor (not shown) to the turbine blades. Numeral
82
denotes an air return pipe. Numerals
83
and
84
denote pipes for feeding the air or the steam cooling medium to the stationary blades
71
-
1
to
71
-
3
, respectively, and recovering it (In
FIG. 8
, this is only shown for the stationary blade
71
-
1
and the others are omitted). Numerals
85
and
86
denote pipes for feeding the cooling medium to the moving blades
72
-
1
to
72
-
3
, respectively, and recovering it. In the same manner, this is only shown for the moving blade
72
-
1
and the others are omitted. Numeral
87
denotes a pipe for connecting the three-way valves
77
and
75
to each other.
In the starting operation of thus constructed gas turbine, the three-way valve
77
is switched to close the steam feed pipe
80
side and open the air feed pipe
81
side to introduce the air from the compressor through the pipe
81
to the pipe
87
. This air is used as the cooling air for cooling the turbine blades during regular operation, but is used for warming the passages within the turbine blades during the starting operation. Thereafter, the air passes through the pipe
83
via the three-way valve
75
and is introduced to and passed the stationary blades
71
-
1
to
71
-
3
. Then, the air which has been passed out of the stationary blades passes through the pipe
84
and the three-way valve
74
and is recovered on the compressor side from the three-way valve
76
through the pipe
82
. Also, at the same time, the air passes through the pipe
85
from the three-way valve
75
and is introduced into the moving blades
72
-
1
to
72
-
3
to be passed through the moving blades. The air that has been passed out of the moving blades passes through the pipe
86
and the three-way valve
74
, to be recovered on the compressor side from the three-way valve
76
through the pipe
82
.
When the stationary blades
71
-
1
to
71
-
3
and the moving blades
72
-
1
to
72
-
3
are warmed by the air from the compressor to a temperature that is suitable for the steam flow, the three-way valves
77
and
76
are switched to close the air feed pipes
81
and
82
and open the steam feed pipe
80
to feed steam to the gas turbine blades instead of the air from the compressor. Then, when the steam passes through the stationary blades
71
-
1
to
71
-
3
and the moving blades
72
-
1
to
72
-
3
, the gas turbine enters normal operating conditions.
Thus, in the starting operation of the gas turbine, the cooling air from the compressor to be used as the cooling medium for cooling the high temperature components during regular operation is used for warming the flow passages within the gas turbine blades. When the temperature of the flow passages, i.e., the cooling medium flow passages, becomes, due to the air from the compressor, equal to or higher than a temperature at which dew is not formed when the steam flows, the three-way valve is switched to stop the flow of the cooling air and circulate the cooling steam.
Subsequently,
FIG. 7
shows another example of a method for starting a gas turbine using a steam cooled system. In
FIG. 7
, a gas turbine system
101
is composed of a compressor
104
, a combustor
106
coupled with the compressor
104
and a gas turbine
108
rotatably driven by the combustion gas. The compressor
104
and the gas turbine
108
are connected to each other through a single axis and are connected to the power generator
100
a.
A steam turbine system
102
is composed of a waste heat recovery boiler
112
for introducing the waste gas from the gas turbine
108
through an exhaust gas passage
111
, a steam turbine
114
rotatably driven by the steam fed from the boiler
112
through a steam passage
113
b
and a steam condenser
116
for converting back into water the waste steam (gas-liquid two-phase flow) of the steam turbine
114
introduced through a waste steam passage
115
. The condensed water generated in the steam condenser
116
is circulated to the waste heat recovery boiler
112
through a condenser pump
117
and a condenser pipe
118
. A power generator
100
b
is connected to the steam turbine
114
. Regulator valves
119
a
and
119
b
and check valves
200
a
and
200
b
are provided in the steam passages
113
a
and
113
b,
respectively. Also, a regulator valve
121
is provided in the steam passage
115
.
A cooling steam system
103
for cooling the gas turbine
108
is composed of a main system
122
a
and an auxiliary system
122
b.
The main system
122
a
is detoured so as to introduce a portion of one steam passage
113
a
to the stationary blades or moving blades which are the high temperature area
123
of the gas turbine
108
of a gas turbine system
101
. The steam feed source is the waste heat recovery boiler
112
.
In the auxiliary system
122
b,
the steam generating portion is connected to one steam passage
113
a
of the main system
122
a
by an auxiliary steam passage
127
having a check valve
125
and a regulator valve
126
, so that the auxiliary steam is fed to the high temperature area
123
of the gas turbine
108
. After cooling the high temperature area
123
, the auxiliary steam is fed to the steam turbine
114
and discharged to the waste steam passage
115
. An auxiliary circulation passage
128
is connected to the waste steam passage
115
so that the waste steam is circulated to the auxiliary boiler
124
through the auxiliary circulation passage
128
. A regulator valve
129
, a steam condenser
130
and an auxiliary steam pump
131
are provided along the flow direction at the auxiliary circulation passage
128
.
The gas turbine
108
is started only when the auxiliary boiler
124
has already started. In the initial stage, the regulator valve
126
of the auxiliary steam passage
127
is opened, and the cooling auxiliary steam is fed from the auxiliary boiler
124
through the check valve
125
to the high temperature area
123
within the gas turbine
108
. The cooled steam is introduced to the steam condenser
130
through the steam turbine
114
and the regulator valve
129
of the auxiliary circulation passage
128
and is returned as water back to the auxiliary boiler
124
by the auxiliary steam condenser pump
131
.
The amount of steam generated from the waste heat recovery boiler
112
is small in the initial stage of the sta
Hirokawa Kazuharu
Tanaka Katsunori
Uematsu Kazuo
Freay Charles G.
Gartenberg Ehud
Mitsubishi Heavy Industries Ltd.
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