Power plants – Combustion products used as motive fluid
Reexamination Certificate
1999-05-07
2001-06-26
Thorpe, Timothy S. (Department: 3746)
Power plants
Combustion products used as motive fluid
Reexamination Certificate
active
06250064
ABSTRACT:
TECHNICAL FIELD
This invention relates to an integrated air saturation and supersaturation system for gas turbine combustion air.
BACKGROUND OF THE INVENTION
Known equipment to humidify gas turbine inlet (i.e., combustion) air for performance augmentation have included one or the other of the systems described below. These systems are generally used under high load conditions and relatively high ambient temperatures (over about 40° F.).
An evaporative cooler system includes an absorbtive media or other system located in a low velocity section of the air intake duct, and is supplied with water which is exposed to the air flowing through the media for evaporation of the water by energy in the air. The energy used for evaporating the water reduces the temperature of the air to near the saturation point, or wet bulb temperature. The reduced temperature of the air entering the gas turbine compressor increases the gas turbine temperature ratio and mass flow, thereby increasing gas turbine output and efficiency. This system does not have the ability to supersaturate the combustion air, however, without the potential for large water drop entrainment which potentially erodes the compressor blades.
An inlet fogging system includes a plurality of manifolds and nozzles that spray finely atomized water into the combustion air for the gas turbine. The fogging systems are located in the air intake duct and have the ability to humidify air to (or near) the saturation point and in most applications to supersaturate the air. Supersaturation of the air in the duct leads to the potential for the formation of large water drops that can erode compressor blades. Condensation of water in the intake duct also requires a drain system to dispose of the unwanted water. Water entrained in the air entering the compressor does cool the air being compressed to reduce compressor power consumption and thereby increase gas turbine power output. Inlet foggers are difficult to control, however, since measurement of supersaturation is impossible.
A compressor intercooling system involves cooling of air between sections of an air compressor, reducing the compressor power consumption and thereby increasing gas turbine power output. Cooling of the air by intercoolers have included (1) heat exchangers where energy removed from the air is rejected to an external media; and (2) evaporative intercoolers in which water is evaporated into the air being compressed. Heat exchanger type intercoolers remove energy from the gas turbine system which must be replaced by energy from fuel burned, so they significantly decrease efficiency, albeit they do increase power output. Evaporative intercoolers perform essentially the same function as inlet air supersaturation, but evaporative intercooling is performed in interstage pressure vessels, which are costly and which introduce pressure drops which degrade gas turbine performance. Moreover, intercooling systems typically must be used under all operating conditions.
BRIEF SUMMARY OF THE INVENTION
This invention relates to an integrated air saturation and supersaturation system for gas turbine combustion air to provide maximum augmentation of power and efficiency during high load operation at ambient air temperature in excess of a practical minimum temperature of about 40° F. (4.44° C.).
In the exemplary embodiments, the integral system includes a spray type or media type evaporative cooler which introduces atomized water into the gas turbine inlet air in the inlet region of the intake duct (well upstream of the compressor inlet) which humidifies the air with water at or near the saturation point. At the same time, water spray nozzles are located in the gas turbine air intake duct in close proximity to the compressor inlet, at the outlet end of the intake duct, which introduce finely atomized water to the previously humidified combustion air to supersaturate it and thus cool the compressor as explained further herein.
The system also includes a control arrangement to deliver and manage the saturation and supersaturation water introduced into the gas turbine inlet or combustion air to optimize the gas turbine performance augmentation within the overall limits of the gas turbine components.
Accordingly, in its broader aspects, the present invention relates to a gas turbine combustion air cooling system comprising a duct having an inlet region and an outlet, said duct adapted to supply ambient air to an inlet of a compressor; a first set of nozzles for spraying atomized water into the ambient air at a location adjacent the duct inlet; a second set of nozzles for spraying atomized water into the ambient air to supersaturate the ambient air at a location proximate the compressor inlet; and control means for apportioning water to the first and second sets of nozzles.
In another aspect, the invention relates to a method of augmenting gas turbine power output in a system comprising a gas turbine, a combustor and a compressor comprising a) saturating combustion air upstream of an inlet to the compressor with water to cool the combustion air to a temperature at or near the wet bulb temperature; and b) supersaturating the combustion air at a location closely adjacent the inlet to the compressor to thereby permit liquid water entrained in the combustion air to enter the compressor where it is evaporated to cool the air being compressed in the compressor.
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George Anthony James
Tomlinson Leroy Omar
General Electric Co.
Nixon & Vanderhye
Rodriguez W
Thorpe Timothy S.
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