Power plants – Combustion products used as motive fluid
Reexamination Certificate
1998-05-29
2001-01-30
Kim, Ted (Department: 3746)
Power plants
Combustion products used as motive fluid
C060S039190, C060S039830, C290S002000
Reexamination Certificate
active
06178733
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to combustion turbine systems and prime movers for combustion turbine systems that can be used to power a blower that produces air for cooling an electrical generator and to selectively power a compressor of the combustion turbine system. This invention also relates to methods of using these prime movers and combustion turbine systems that employ them.
Combustion turbine systems generally include a compressor, a combustor and a turbine section. The compressor compresses air, and the air is directed to the combustor. In the combustor, the air is mixed with fuel, and this mixture is burned to produce a hot gas. The hot gas is sent through the turbine section of the combustion turbine system where a portion of the energy in the hot gas is converted into useful work. This work may include rotation of a rotor which drives a load, such as an electrical generator. After traveling through the turbine section, the hot gas is exhausted from the combustion turbine.
Typically, the compressor and the electrical generator are both mounted on the rotor that extends through the turbine section of the combustion turbine system.
Therefore, as the hot gas flows through the turbine section and causes the rotor to rotate, the compressor and the electrical generator are both driven by the rotation of the rotor. Thus, when the rotor shaft is driven in the turbine section by the expansion of the hot gas, electricity can be produced by the electrical generator.
Because electrical generators produce a significant amount of heat, they must be cooled. A heat exchanger may be disposed within the electrical generator in order to provide the requisite cooling. The heat exchanger may be employed in a cooling circuit that includes a blower for supplying air as the cooling medium to the heat exchanger and a cooler for cooling the air after it has been heated while traveling through the heat exchanger.
In prior art combustion turbine systems, the blower that provides cooling for the electrical generator may be mounted on a shaft of the electrical generator, so that rotation if the rotor shaft by the hot gas produced in the turbine section of the combustion turbine system will cause rotation of the blower. In other words, the combustion turbine acts as the prime mover for the blower.
In order to start a gas turbine, the compressor must be started so that is can provide the air at the requisite pressure for mixing with fuel to produce a hot gas to drive the rotor. As alluded to above, during normal operations of a combustion turbine system the compressor is powered by the hot gas that expands and drives the rotor in the turbine section. Since the mixture of fuel and compressed air needed to drive the turbine rotor and the compressor is not available upon starting the combustion turbine, a prime mover must be provided in order to start the compressor. Typically, the prime mover is an electrical induction motor. After the combustion turbine has been started and sufficient hot gas is produced, the compressor is powered by the rotation of the rotor and the prime mover that powers the compressor is no longer required.
In prior art combustion turbine systems, the prime mover for powering the blower motor for the cooling circuit of the electrical generator and the prime mover for starting the compressor were separate components. The prime mover for starting the compressor was used to merely start the compressor, and the prime mover for the blower was the combustion turbine.
This invention relates to improved combustion turbine systems that employ prime movers that can be used to selectively power a compressor upon starting a combustion turbine and be used to power a blower for producing a cooling medium for an electrical generator. This invention also relates to these prime movers themselves, and improved methods of using these combustion turbine systems employing the prime movers.
SUMMARY OF THE INVENTION
A combustion turbine system of this invention includes a rotor, a compressor, a combustor, a turbine section, a blower, an electrical generator and an external prime mover for powering the blower and turning the rotor. The compressor produces a compressed air that mixes with fuel in the combustor to produce a hot gas. This hot gas is sent through the turbine section of the combustion turbine system to drive the rotor. The electrical generator may be coupled to the rotor, so that rotation of the rotor causes operation of the electrical generator. The rotor may also be coupled to the compressor, so that the rotation of the rotor also drives the compressor. The blower provides a cooling medium for the electrical generator.
The prime mover is coupled to the blower so that it can power the blower and provide the cooling medium for the electrical generator. In addition, the prime mover is selectively connectable to the rotor, so that it can turn the rotor. In a preferred embodiment of this invention, the prime mover is an electrical motor. The prime mover can turn the rotor when the combustion turbine is not producing sufficient hot gas to drive the rotor, for example when the combustion turbine is being started. After the combustion turbine has been started and provides a sufficient amount of hot gas to turn the rotor, the prime mover for the rotor is no longer needed and can be disconnected from the rotor and the turbine section can act as the prime mover for the rotor.
In order to selectively couple the prime mover to the rotor, the combustion turbine system may have a clutch or torque converter disposed between the prime mover and the compressor. Upon starting the combustion turbine system, the clutch or torque converter can be operated to couple the prime mover to the rotor and thereby provide power to the rotor. After the combustor produces sufficient hot gas to drive the rotor and the compressor, the clutch can be operated to decouple the prime mover from the compressor. The blower may be disposed between the prime mover and the clutch, so that the prime mover powers the blower irrespective of the position of the clutch.
The blower may be disposed in either a closed cooling circuit for the electrical generator or an open cooling system. If employed in a closed cooling system, the system may include a heat exchanger. The head exchanger may be disposed in the electrical generator to cool the cooling medium. After being pressurized by the blower, the cooling medium can flow through the generator and absorb heat produced by the generator. The cooling medium may then be cooled by the heat exchanger and then recirculated by the blower through the cooling circuit.
If the blower is employed in an open loop cooling system, the blower sends ambient air through the generator to cool the generator. The air is not recirculated in this type of system, but rather is exhausted to atmosphere.
Since the blower is powered by the prime mover, the blower is not powered by the turbine as in a conventional system. The conventional shaft mounted blowers are less efficient than the external blower of this invention. Therefore, this invention may increase the efficiency of the turbine system.
The external blower of this invention can also be used with a steam turbine system. As is conventional, a steam turbine system may have a condenser, a turbine, a steam generator and an electrical generator. The electrical generator may be coupled to the steam turbine so that the steam turbine is the prime mover for the electrical generator. Similar to the electrical generator used in a gas turbine system, the electrical generator of the steam turbine system also requires cooling. According to this invention, an external blower that is external to the electrical generator may be used to supply a cooling medium to the generator. The blower is external in that it is not contained within the generator enclosure that encases the electrical generator.
Similar to the electrical generator of the gas turbine system, the electrical generator of the steam turbine system may have either an open or a closed loop coo
Eckert Seamans Cherin & Mellott , LLC
Kim Ted
Siemens Westinghouse Power Corporation
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