Power plants – Combustion products used as motive fluid – Multiple fluid-operated motors
Reexamination Certificate
2000-10-27
2002-05-21
Kim, Ted (Department: 3746)
Power plants
Combustion products used as motive fluid
Multiple fluid-operated motors
C060S736000, C060S039780
Reexamination Certificate
active
06389797
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a gas turbine combined cycle system and more particularly to a gas turbine combined cycle system in which heating of fuel and cooling of gas turbine moving blade and stationary blade cooling air are carried out by steam generated at a waste heat recovery boiler so as to enhance an efficiency.
2. Description of the Prior Art
FIG. 14
is a system diagram of a gas turbine combined cycle system in the prior art. In
FIG. 14
, the prior art combined cycle system is constructed by a gas turbine
8
, a waste heat recovery boiler
9
and a steam turbine
29
. In the gas turbine
8
, suction air is taken into a compressor
2
to be compressed to a predetermined pressure and while the compressed air is partially used for cooling of gas turbine blades, the most part thereof is led into a combustor
3
to be mixed with fuel for generation of a high temperature gas. The high temperature gas enters a turbine
6
to expand for work and a turbine output after deduction of a compressor output generates an electric power at a generator
1
.
While outlet air of the compressor
2
is partially used for blade cooling in the turbine
6
, this air, having a high temperature, is cooled to a predetermined temperature at a blade cooling air cooler
4
using a cooling fan
5
and is then used for the turbine blade cooling. Thus, the air so led from the compressor
2
is once cooled at the blade cooling air cooler
4
using the cooling fan
5
to be then supplied into the turbine
6
. By this cooling using the cooling fan
5
, heat of the blade cooling air cooler
4
is discharged outside in vain and this has caused a reduction in the thermal efficiency of the gas turbine and the combined cycle system (gas turbine efficiency and combined efficiency). It is to be noted that the fuel is supplied into the combustor
3
without being preheated.
On the other hand, as for the waste heat recovery boiler
9
, outlet steam of a low pressure turbine
23
is converted into water from steam at a condenser
25
. Then, the water is pressurized at a feed water pump
26
and heated at a feed water heater
10
to become a saturated water. This saturated water is separated into three systems of water. The first one becomes a saturated steam at a low pressure evaporator
11
and becomes a superheated steam at a low pressure superheater
15
and is then supplied to an inlet of the low pressure turbine
23
. The second one is pressurized to a predetermined pressure at an intermediate pressure pump
28
, becomes a saturated water at an intermediate pressure economizer
12
, becomes a saturated steam at an intermediate pressure evaporator
14
and becomes a superheated steam at an intermediate pressure superheater
16
and is then supplied to an inlet of a reheater
20
.
And the third one is pressurized to a predetermined pressure at a high pressure pump
27
, becomes a saturated water at a first high pressure economizer
13
and a second high pressure economizer
17
, becomes a saturated steam at a high pressure evaporator
18
and becomes a superheated steam at a high pressure superheater
19
and is then led into a high pressure turbine
21
. The mentioned superheated steam enters the high pressure turbine
21
, the intermediate pressure turbine
22
and the low pressure turbine
23
, respectively, to expand for generating an output and this output is converted into an electric power at a generator
24
.
As mentioned above, in the prior art gas turbine combined cycle system, the fuel is supplied into the combustor without being preheated and the compressed air from the compressor is partially led into the blade cooling air cooler to be cooled and is then supplied for cooling of the gas turbine moving blades and stationary blades. Cooling of the combustor is also done by cooling air. The air for cooling the blades is once cooled at the blade cooling air cooler using the cooling fan and the heat obtained by the cooling is discharged outside in vain and this has caused a reduction in thermal efficiency of the gas turbine and the combined cycle system.
SUMMARY OF THE INVENTION
In view of the mentioned problem in the prior art, therefore, it is an object of the present invention to provide a gas turbine combined cycle system in which fuel to be supplied into a gas turbine combustor is preheated by steam taken from a waste heat recovery boiler, a combustor tail tube is cooled by the steam taken from the waste heat recovery boiler in place of air and gas turbine moving blades and stationary blades are also cooled by the steam taken from the waste heat recovery boiler and further the steam after used for cooling the combustor tail tube or the gas turbine moving blades and stationary blades is recovered to be recycled so that efficiency of the gas turbine and the combined cycle system may be enhanced.
In order to achieve the mentioned object, the present invention provides means of the following (1) to (13):
(1) A gas turbine combined cycle system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling system for cooling the combustor and blades of the turbine; and a waste heat recovery boiler having components of a feed water heater, an intermediate pressure economizer, a low pressure superheater, an intermediate pressure superheater, a high pressure superheater, a high pressure evaporator and a reheater and being fed with exhaust gas of the gas turbine so that condensed water coming from the condenser may be heated and vaporized via the components of the waste heat recovery boiler for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, characterized in that there is provided a fuel heater for heating the fuel before the fuel enters the combustor and saturated water coming from the intermediate pressure economizer of the waste heat recovery boiler is partially diverged to flow to the fuel heater for heating the fuel and the saturated water so used for heating the fuel is supplied to an inlet of the feed water heater.
(2) A gas turbine combined cycle system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling system for cooling the combustor and blades of the turbine; and a waste heat recovery boiler having components of a feed water heater, an intermediate pressure economizer, a low pressure superheater, an intermediate pressure superheater, a high pressure superheater, a high pressure evaporator and a reheater and being fed with exhaust gas of the gas turbine so that condensed water coming from the condenser may be heated and vaporized via the components of the waste heat recovery boiler for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, characterized in that there is provided a fuel heater for heating the fuel before the fuel enters the combustor and saturated water coming from the intermediate pressure economizer of the waste heat recovery boiler is partially diverged to flow to the fuel heater for heating the fuel and the saturated water so used for heating the fuel is supplied to the condenser.
(3) A gas turbine combined cycle system as mentioned in (1) or (2) above, characterized in that the cooling system for cooling the combust
Matsuda Hideo
Mori Hidetaka
Sugishita Hideaki
Uematsu Kazuo
Kim Ted
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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