Gas turbine efficiency and regulation speed improvements using supplementary air system continuous and storage systems and methods of using the same

Abstract

The present invention discloses a novel apparatus and methods for augmenting the power of a gas turbine engine, improving gas turbine engine operation, and reducing the response time necessary to meet changing demands of a power plant. Improvements in power augmentation and engine operation include additional heated compressed air injection from a power augmentation system and a motor-generator in selective operation with the power augmentation system.

Claims

1. A back-up power supply system for a power plant comprising: a reciprocating engine coupled to a generator and an intercooled compressor; where the reciprocating engine provides shaft power to turn the generator resulting in electricity production from the generator available for use by the power plant for start-up operations of a gas turbine engine and to the intercooled compressor for providing compressed air to the gas turbine engine of the power plant, and where the compressed air of the intercooled compressor is heated with exhaust from the reciprocating engine.

2. The back-up power supply system of claim 1, wherein the generator produces a maximum of two megawatts of electricity.

3. The back-up power supply system of claim 1, wherein the electricity generated by the generator provides an electrical supply required to start a gas turbine engine when grid power is unavailable.

4. The back-up power supply system of claim 1, wherein the reciprocating engine generates a heat source during operation.

5. The back-up power supply system of claim 1 further comprising a clutch engaging the reciprocating engine and the generator.

6. The back-up power supply system of claim 1, wherein coupling the generator to the reciprocating engine provides a standalone power supply.

7. The back-up power supply system of claim 1, wherein the generator provides electrical power to the power plant when the power plant is offline.

8. The back-up power supply system of claim 1, wherein the reciprocating engine and the generator are used in parallel to respond to increasing power to an electric grid.

9. The back-up power supply system of claim 1, wherein the generator is a combined motor-generator.

10. A back-up power supply system for a power plant comprising: a fueled engine; a generator coupled to the fueled engine; and an intercooled compressor; wherein the fueled engine is a reciprocating engine providing shaft power to the generator for producing a supply of electricity for use by the power plant for start-up operations of a gas turbine engine and to the intercooled compressor for providing compressed air to the gas turbine engine of the power plant.

11. The back-up power supply system of claim 10, wherein the generator provides a maximum of two megawatts of power to the power plant.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The present invention is described in detail below with reference to the attached drawing figures, wherein:

(2) FIG. 1 is a schematic drawing of an embodiment of the present invention having a supplemental energy system with a recuperated engine driving the supplemental compressor.

(3) FIG. 2 is a schematic drawing of an embodiment of the present invention having a supplemental energy system with a recuperated engine driving the supplemental compressor and energy storage.

(4) FIG. 3 is a schematic drawing of an embodiment of the present invention incorporating a continuous power augmentation system.

(5) FIG. 4 is a schematic drawing of an embodiment of the present invention in which an auxiliary steam turbine is drives the supplemental compressor.

(6) FIG. 5 is a schematic drawing of an embodiment of the present invention in which includes an auxiliary steam turbine driving the supplemental compressor and energy storage.

(7) FIG. 6 is a schematic drawing of an embodiment of the present invention installed in conjunction with two gas turbines and a steam turbine.

(8) FIG. 7 is a schematic drawing of an embodiment of the present invention installed in conjunction with one gas turbine and a steam turbine.

(9) FIG. 8 is a schematic drawing of an embodiment of the present invention installed in conjunction with one gas turbine.

(10) FIG. 9 is a schematic drawing of an embodiment of the present invention utilizing a power augmentation system and a motor-generator.

(11) FIG. 10 is a flow diagram depicting an alternate embodiment of the present invention.

(12) FIG. 11 is a flow diagram depicting yet another alternate embodiment of the present invention.

DETAILED DESCRIPTION

(13) The components of one embodiment of the present invention are shown in FIG. 1 as they are used with an existing gas turbine system 1. The existing gas turbine system 1, which compresses ambient air 2, includes a compressor 10, combustor 12, combustion case 14, turbine 16 and generator 18. A fueled engine 20 is used to drive a multistage intercooled supplemental compressor 22 which compresses ambient air 24 and discharges compressed air 26. As used herein, the term fueled engine means a reciprocating internal combustion engine, a gas turbine (in addition to the gas turbine in the existing gas turbine system 1, or a similar machine that converts fuel into energy through an exothermic reaction such as combustion (e.g., gasoline, diesel, natural gas, or biofuel and similar fuel). The fueled engine draws in ambient air 42 and as a result of the combustion process, produces hot exhaust gas 32. As those skilled in the art will readily appreciate, as air in the supplemental compressor 22 passes from one compressor stage to the next, the air is intercooled by use of an intercooler heat exchanger 28, such as a cooling tower, to reduce the work required to compress the air at the subsequent compressor stage. As used herein, the term intercooler heat exchanger means a heat exchanger that receives compressed air from an upstream stage of a compressor, and cools that air before delivering it to another compression stage downstream of the upstream compressor stage. Use of the intercooler heat exchanger 28 increases the efficiency of the supplemental compressor 22, which makes it more efficient than the compressor 10 of the existing gas turbine system 1. As those skilled in the art will readily appreciate, although referred to herein as an intercooler, the intercooler heat exchanger 28 actually includes an intercooler and an after-cooler as described in greater detail below.

(14) This embodiment further includes a recuperator 30, which is a heat exchanger that receives the exhaust gas 32 from the fueled engine 20 and the compressed air 26 from the supplemental compressor 22. Flow of compressed air from the supplemental compressor 22 to the recuperator 30 is controlled by the recuperator flow control valve 44. Within the recuperator 30, the hot exhaust gas 32 heats the compressed air 26 and then exits the recuperator 30 as substantially cooler exhaust gas 34. At the same time in the recuperator 30, the compressed air 26 absorbs heat from the exhaust gas 32 and then exits the recuperator 30 as substantially hotter compressed air 36 than when it entered the recuperator 30. The substantially hotter compressed air 36 is then discharged from the recuperator 30 into the combustion case 14 of the gas turbine system 1 where it becomes an addition to the mass flow through the turbine 16.

(15) The cooler exhaust gas 34 is then discharged to atmosphere. A selective catalytic reduction (SCR) device (not shown) of the type known in the art, can be inserted before, in the middle of, or after the recuperator 30 to achieve the most desirable condition for the SCR function. Alternately, after the SCR device, the cooler exhaust gas 34 can be injected into the exhaust gas 38 of the turbine 16 as shown in FIG. 1, and then the mixed flow exhaust 38 will either be discharged to the atmosphere (in the case for the simple cycle gas turbine) or directed to the heat recovery steam generator (HRSG) of a steam turbine of the type known in the art (not shown) in combined cycle power plants. If the mixed flow exhaust 38 is to be discharged into the HRSG, the means used must ensure that the exhaust gas 38 flow from the turbine 16 into the HRSG and the SCR device is not disrupted. On F-Class engines, such as the General Electric Frame 9FA industrial gas turbine, there are large compressor bleed lines that, for starting purposes, bypass air around the turbine section and dump air into the exhaust plenum of the turbine 16. These bleed lines are not in use when the gas turbine system 1 is loaded, and therefore are a good place to discharge the cooler exhaust gas 34 after it exits the recuperator 30, since these compressor bleed lines are already designed to minimize the impact on the HRSG and SCR device. By injecting the exhaust 32 from the fueled engine 20 into to exhaust 38 of the gas turbine system 1, the SCR of the gas turbine system 1 may be used to clean the exhaust 32, thus eliminating an expensive system on the fueled engine 20.

(16) It turns out that gasoline, diesel, natural gas, or biofuel and similar reciprocating engines are not sensitive to back pressure, so putting the recuperator 30, on the fueled engine 20 does not cause a measurable effect on the performance of the fueled engine 20. This is significant because other heat recovery systems, such as the HRSGs used in the exhaust of a typical gas turbine power plants, create a significant power loss all of the time, independent of whether a power augmentation system is in use or not.

(17) The power from the fueled engine 20 is used to drive the intercooled compressor 22. If the installation does include a HS G and a steam turbine, the auxiliary heat from the engine jacket, oil cooler and turbocharger on the fueled engine 20 can be transferred into the steam cycle of the steam turbine via the HSRG (typically the low pressure and temperature condensate line) Likewise, heat removed by the intercooler heat exchanger 28 from the air as it is compressed in the multistage supplemental compressor 22 can be transferred into the steam cycle in a similar manner, prior to the compressed air being cooled by the cooling tower, to lower the temperature of the compressed air to the desired temperature prior to entering the subsequent compression stage of the supplemental compressor 22. If an auxiliary gas turbine is used as the fueled engine 20 instead of a reciprocating engine, lower emission rates will be achievable, which will allow emission permitting even in the strictest environmental areas. Also, if the auxiliary gas turbine is used as the fueled engine 20, the exhaust gas from the auxiliary gas turbine can be piped directly to the exhaust bleed pipes of the existing gas turbine system 1 described above, thus avoiding the cost and maintenance of an additional SCR device.

(18) When peaking with this system, the gas turbine system 1 will most likely be down in power output and flow (assuming that the peaking is needed in the summer when higher ambient air temperatures reduce total mass flow through the gas turbine system 1 which in turn reduces power output of the gas turbine system 1 as a whole, and the supplemental compressor 22 will just bring the air mass flow through the gas turbine system 1 back up to where the flow would have been on a cooler day (i.e. a day on which the full rated power of the gas turbine system 1 could be achieved).

(19) FIG. 2 shows the embodiment of FIG. 1 with the addition of compressed air storage. The compressed air storage system includes an air storage tank 50, a hydraulic fluid tank 52, and a pump 54 for transferring hydraulic fluid, such as water, between the hydraulic fluid tank 52 and the air storage tank 50. According to preferred embodiments, during periods when increased power delivery is needed, the air exit valve 46 opens, the air bypass valve 48 opens, the air inlet valve 56 closes, and the supplemental compressor 22 is operated, driven by the fueled engine 20. As one skilled in the art will readily appreciate, if compressed air is to be stored for later use, it will likely need to be stored at a higher pressure, thus, the supplemental compressor 22 would preferably have additional stages of compression, as compared to the supplemental compressor 22 of the embodiment shown in FIG. 1. These additional stages may be driven by the fueled engine 20 all the time, or may be capable of being driven intermittently by installing a clutch type mechanism that only engages the additional stages when the fueled engine 20 is operated to store compressed air in the air storage tank 50 (where the desired storage pressure is substantially higher to minimize the required volume of the air storage tank 50). Alternatively, the additional stages may be decoupled from the fueled engine 20 and driven by a separately fueled engine (not shown) or other means, such as an electric motor.

(20) The compressed air 26 flowing from the supplemental compressor 22 is forced to flow to the mixer 58 as opposed to towards the intercooler heat exchanger 28 because the air inlet valve 56, which controls air flow exiting the intercooler heat exchanger 28, is closed. The compressed air 26 flowing from the outlet of the supplemental compressor 22 is mixed in the mixer 58 with the compressed air exiting the air storage tank 50 and introduced to the recuperator 30 where it absorbs heat from the exhaust gas of the fueled engine 20 before being introduced into the combustion case 14 using the process described below. As those skilled in the art will readily appreciate, for thermal efficiency purposes, the recuperator 30 would ideally be a counter-flow heat exchanger, since that would allow the maximum amount of heat from the exhaust 32 to be transferred to the compressed air exiting the air storage tank 50. Alternately, if the recuperator 30 is made up of one or more cross-flow heat exchangers, it can have a first stage, which is a first cross-flow heat exchanger, followed by a second stage, which is a second cross-flow heat exchanger. In this configuration, where the exhaust 32 first enters the first stage of the recuperator, is partially cooled, then flows to the second stage of the recuperator. At the same time, the compressed air exiting the air storage tank 50 first enters the second stage of the recuperator 30, where additional heat is extracted from the partially cooled exhaust 32, thereby pre-heating the compressed air. The compressed air then flows to the first stage of the recuperator 30 where it is heated by exhaust 32 that has not yet been partially cooled, prior to flowing to the mixer 58 to join the air flowing from the supplemental compressor 22. In this case, the two stage recuperator acts more like a counter-flow heat exchanger, yielding higher thermal efficiency in the heating of the compressed air.

(21) As those skilled in the art will readily appreciate, since the air being compressed in the supplemental compressor 22 is bypassing the intercooler heat exchanger 28 due to the bypass valve 48 being open, the compressed air exiting the supplemental compressor 22 retains some of the heat of compression, and when mixed with the compressed air flowing from the air storage tank 50, will increase the temperature of the mixed air so that when the mixed air enters the recuperator 30, it is hotter than it would be if only compressed air from the air storage tank 50 was being fed into the recuperator 30. Likewise, if the air exiting the air storage tank 50 is first preheated in a second stage of the recuperator as described above prior to entering the mixer 58, an even hotter mixture of compressed air will result, which may be desirable under some conditions.

(22) As the combustion turbine system 1 continues to be operated in this manner, the pressure of the compressed air in the air storage tank 50 decreases. If the pressure of the compressed air in the air storage tank 50 reaches the pressure of the air in the combustion case 14, compressed air will stop flowing from the air storage tank 50 into the gas turbine system 1. To prevent this from happening, as the pressure of the compressed air in the air storage tank 50 approaches the pressure of the air in the combustion case 14, the fluid control valve 60 remains closed, and the hydraulic pump 54 begins pumping a fluid, such as water, from the hydraulic fluid tank 52 into the air storage tank 50 at a pressure high enough to drive the compressed air therein out of the air storage tank 50, thus allowing essentially all of the compressed air in the air storage tank to be delivered to the combustion case 14.

(23) As those skilled in the art will readily appreciate, if additional compressor stages, or high pressure compressor stages, are added separate from the supplemental compressor 22 driven by the fueled engine 20, then, if desired, air from the gas turbine combustion case 14 can be bled and allowed to flow in reverse of the substantially hotter compressed air 36 as bleed air from the gas turbine combustion case 14 and take the place of air from the separately fueled engine 20 driven supplemental compressor 22. In this case, the bleed air could be cooled in the intercooler heat exchanger 28, or a cooling tower, and then delivered to the inlet of the high pressure stages of the supplemental compressor 22. This may be especially desirable if low turn down capability is desired, as the bleed air results in additional gas turbine power loss, and the drive system for the high pressure stages of the supplemental compressor 22 can driven by an electric motor, consuming electrical power generated by the gas turbine system 1, which also results in additional gas turbine power loss. As those skilled in the art will readily appreciate, this is not an operating mode that would be desirable during periods when supplemental power production from the gas turbine system is desired.

(24) According to preferred embodiments, independent of whether or not the hydraulic system is used, when the air stops flowing from the air storage tank 50, the supplemental compressor 22 can continue to run and deliver power augmentation to the gas turbine system 1. According to other preferred embodiments, such as the one shown in FIG. 1, the supplemental compressor 22 is started and run without use of an air storage tank 50. Preferably, an intercooler heat exchanger 28 is used to cool air from a low pressure stage to a high pressure stage in the supplemental compressor 22 that compresses ambient air 24 through a multistage compressor 22.

(25) The air inlet valve 56, the air outlet valve 46, the bypass valve 48, and the supplemental flow control valve 44, are operated to obtain the desired operating conditions of the gas turbine system 1. For example, if it is desired to charge the air storage tank 50 with compressed air, the air outlet valve 46, the bypass valve 48 and the supplemental flow control valve 44 are closed, the air inlet valve 56 is opened and the fueled engine 20 is used to drive the supplemental compressor 22. As air is compressed in the supplemental compressor 22, it is cooled by the intercooler heat exchanger 28 because the bypass valve 48 is closed, forcing the compressed air to flow through the intercooler heat exchanger 28. Air exiting the supplemental compressor 22 then flows through the air inlet valve 56 and into the air storage tank 50. Likewise, if it is desired to discharge compressed air from the air storage tank 50 and into the combustion case 14 the air outlet valve 46, the bypass valve 48 and the supplemental flow control valve 44 are opened, and the air inlet valve 56 can be closed, and the fueled engine 20 can be used to drive the supplemental compressor 22.

(26) As air is compressed in the supplemental compressor 22, it heats up due to the heat of compression, and it is not cooled in the intercooler heat exchanger because bypass valve 48 is open, thereby bypassing the intercooler heat exchanger. Compressed air from the air storage tank 50 then flows through the mixer 58 where it is mixed with hot air from the supplemental compressor 22 and then flows to the recuperator 30 where it absorbs heat transferred to the recuperator 30 from the exhaust gas 32 of the fueled engine 20 and then flows on to the combustion case 14. In the event that all of the airflow from the supplemental compressor 22 is not needed by the gas turbine system 1, this embodiment can be operated in a hybrid mode where the some of the air flowing from the supplemental compressor 22 flows to the mixer 58 and some of the air flow from the supplemental compressor 22 flows through the intercooler heat exchanger 28 and then through the air inlet valve 56 and into the air storage tank 50.

(27) As those skilled in the art will readily appreciate, the preheated air mixture could be introduced into the combustion turbine at other locations, depending on the desired goal. For example, the preheated air mixture could be introduced into the turbine 16 to cool components therein, thereby reducing or eliminating the need to extract bleed air from the compressor to cool these components. Of course, if this were the intended use of the preheated air mixture, the mixture's desired temperature would be lower, and the mixture ratio in the mixer 58 would need to be changed accordingly, with consideration as to how much heat, if any, is to be added to the preheated air mixture by the recuperator 30 prior to introducing the compressed air mixture into the cooling circuit(s) of the turbine 16. Note that for this intended use, the preheated air mixture could be introduced into the turbine 16 at the same temperature at which the cooling air from the compressor 10 is typically introduced into the TCLA system of the turbine 16, or at a cooler temperature to enhance overall combustion turbine efficiency (since less TCLA cooling air would be required to cool the turbine components).

(28) It is to be understood that when the air storage tank 50 has hydraulic fluid in it prior to the beginning of a charging cycle to add compressed air to the air storage tank 50, the fluid control valve 60 is opened so that as compressed air flows into the air storage tank 50 it drives the hydraulic fluid therein out of the air storage tank 50, through the fluid control valve 60, and back into the hydraulic fluid tank 52. By controlling the pressure and temperature of the air entering the turbine system 1, the gas turbine system's turbine 16 can be operated at increased power because the mass flow of the gas turbine system 1 is effectively increased, which among other things, allows for increased fuel flow into the gas turbine's combustor 12. This increase in fuel flow is similar to the increase in fuel flow associated with cold day operation of the gas turbine system 1 where an increased mass flow through the entire gas turbine system 1 occurs because the ambient air density is greater than it is on a warmer (normal) day.

(29) During periods of higher energy demand, the air flowing from the air storage tank 50 and supplemental compressor 22 may be introduced to the gas turbine system 1 in a manner that offsets the need to bleed cooling air from the compressor 10, thereby allowing more of the air compressed in the compressor 10 to flow through the combustor 12 and on to the turbine 16, thereby increasing the net available power of the gas turbine system 1. The output of the gas turbine 16 is very proportional to the mass flow rate through the gas turbine system 1, and the system described above, as compared to the prior art patents, delivers higher flow rate augmentation to the gas turbine 16 with the same air storage volume and the same supplemental compressor size, when the two are used simultaneously to provide compressed air, resulting in a hybrid system that costs much less than the price of prior art systems, while providing comparable levels of power augmentation.

(30) The supplemental compressor 22 increases the pressure of the ambient air 24 through at least one stage of compression, which is then cooled in the intercooler heat exchanger 28, further compressed in a subsequent stage of the supplemental compressor 22, and then after-cooled in the intercooler heat exchanger 28 (where the compressed air exiting the last stage of the supplemental compressor 22 is then after-cooled in the same intercooler heat exchanger 28), and then the cooled, compressed, high pressure air is delivered to the air storage tank 50 via the open air inlet valve 56 and the inlet manifold 62, and is stored in the air storage tank 50.

(31) As the pressurized air flowing through the intercooler heat exchanger 28 is cooled, the heat transferred therefrom can be used to heat water in the H SG to improve the efficiency of the steam turbine. An alternate method to cool the compressed air in the intercooler heat exchanger 28 is to use relatively cool water from the steam cycle (not shown) on a combined cycle plant. In this configuration, the water would flow into the intercooler heat exchanger 28 and pick up the heat that is extracted from the compressed air from the supplemental compressor 22, and the then warmer water would exit the intercooler heat exchanger 28 and flow back to the steam cycle. With this configuration, heat is captured during both the storage cycle described in this paragraph, and the power augmentation cycle described below.

(32) According to preferred embodiments, the air storage tank 50 is above-ground, preferably on a barge, skid, trailer or other mobile platform and is adapted or configured to be easily installed and transported. The additional components, excluding the gas turbine system 1, should add less than 20,000 square feet, preferably less than 15,000 square feet, and most preferably less than 10,000 square feet to the overall footprint of the power plant. A continuous augmentation system of the present invention takes up 1% of the footprint of a combined cycle plant and delivers from three to five times the power per square foot as compared to the rest of the plant, thus it is very space efficient, while a continuous augmentation system of the present invention with storage system takes up 5% of the footprint of the combined cycle plant and delivers from one to two times the power per square foot of the power plant.

(33) FIG. 3 shows another embodiment of the present invention in which an auxiliary gas turbine 64 is used to provide supplemental air flow at times when additional power output from the gas turbine system 1 is needed. The auxiliary gas turbine 64 includes a supplemental compressor section 66 and a supplemental turbine section 68. In this embodiment, the auxiliary gas turbine is designed so that substantially all of the power produced by the supplemental turbine section 68 is used to drive the supplemental compressor section 66. As used herein the term substantially all means that more than 90% of the power produced by the supplemental turbine section 68 is used to drive the supplemental compressor 66, because major accessories, such as the electric generator used with the gas turbine system 1, are not drawing power from the auxiliary gas turbine section 68. Manufacturers of small gas turbines, such as Solar Turbines Inc., have the capability to mix and match compressors and combustors/turbines because they build their systems with multiple bearings to support the supplemental compressor section 66 and the supplemental turbine section 68. A specialized turbine, with an oversized gas turbine compressor 66 and with a regular sized turbine/combustion system 68 is used to provide additional supplemental airflow to the gas turbine system 1, and the excess compressed air 70 output from the oversized compressor 66, which is in excess of what is needed to run the turbine/combustion system 68, flows through the combustion case flow control valve 74, when it is in the open position, and is discharged into the combustion case 14 of the gas turbine system 1 to increase the total mass flow through the turbine 16 of the gas turbine system 1, and therefore increases the total power output by the gas turbine system 1. For example, a 50 lb/sec combustor/turbine section 68 that would normally be rated for 4 MW, may actually be generating 8 MW, but the compressor is drawing 4 MW, so the net output from the generator is 4 MW. If such a turbine were coupled with a 100 lb/sec compressor on it, but only 50 lbs/sec were fed to the combustor/turbine section 68, the other 50 lb/sec could be fed to the combustion case of the gas turbine system 1. The exhaust 72 of the 50 lb/sec combustor/turbine section 68 could be injected into the exhaust 38 of the main turbine 16 similar to the manner described in the embodiment shown in FIG. 1, and jointly sent to the SCR. Optionally, the exhaust can be separately treated, if required.

(34) Obviously, the pressure from the 100 lb/sec compressor 66 has to be sufficient to drive the compressed air output therefrom into the combustion case 14. Fortunately, many of the smaller gas turbine engines are based on derivatives of aircraft engines and have much higher pressure ratios than the large industrial gas turbines used at most power plants. As shown in FIG. 3, this embodiment of the present invention does not include the recuperator 30, the intercooled compressor 22, or the intercooler heat exchanger 28 shown in FIGS. 1 and 2. Of course, the embodiment shown in FIG. 3 does not provide the efficiency improvement of the intercooled embodiments shown in FIGS. 1 and 2, however the initial cost of the embodiment shown in FIG. 3 is substantially less, which may make it an attractive option to operators of power plants that typically provide power in times of peak demand, and that therefore are not run much and are less sensitive to fuel efficiency. When the auxiliary gas turbine 64 is not running, the combustion case flow control valve 74 is closed.

(35) The embodiment shown in FIG. 4 shows another way to incorporate a supplemental compressor 22 into the gas turbine system 1. In some situations, the gas turbine augmentation of the present invention with (i) the additional mass flow to the HRSG, and/or (ii) the additional heat from the intercooler heat exchanger 28 and fueled engine 20 (as compared to a gas turbine system 1 that does not incorporate the present invention), may be too much for the steam turbine and/or the steam turbine generator to handle if all of the additional heat flows to the steam turbine generator (especially if the power plant has duct burners to replace the missing exhaust energy on hot days). In this case, the additional steam generated as a result of adding the heat of compression generated by the supplemental compressor 22 can be extracted from the steam cycle HRSG. As it happens, when compressed air augmentation is added to the gas turbine system 1, the heat energy extracted from the intercooler heat exchanger 28 generates about the same amount of energy that it takes to drive the supplemental compressor 22. In other words, if you had a steam turbine that generated 100 MW normally and 108 MW when the supplemental compressor 22 was injecting compressed air into the gas turbine system 1, the extra 8 MW is approximately equal to the power requirement to drive the intercooled supplemental compressor 22. Therefore, if some of the steam is extracted from the steam cycle of the power plant, and the steam turbine is kept at 100 MW, a small auxiliary steam turbine 76 can be used to drive the intercooled supplemental compressor 22, and there would be no additional source of emissions at the power plant.

(36) In FIG. 4, an auxiliary steam turbine 76 drives the intercooled supplemental compressor 22 and the steam 78 that is used to drive the steam engine 76, which comes from the HRSG (not shown) of the power plant, is the extra steam produced from the heat, being added to the HRSG, which was extracted by the intercooler heat exchanger 22 during compression of air in the supplemental compressor 22. The exhaust 80 of the steam engine 76 is returned to the HRSG where it is used to produce more steam. This embodiment of the present invention results in a significant efficiency improvement because the compression process of the supplemental compressor 22 is much more efficient than the compressor 10 of the gas turbine system 1. In this situation, the power augmentation level will, of course, be reduced as the steam turbine will not be putting out additional MW, however there will be no other source of emissions/fuel burn.

(37) FIG. 5 shows the embodiment of FIG. 4 with the addition of compressed air storage. This implementation of compressed air energy storage is similar to that described with respect to FIG. 2, as is the operation thereof. As those skilled in the art will readily appreciate, the power augmentation level of the embodiment shown in FIG. 5 is less than the embodiment shown in FIG. 2, since the steam turbine will not be putting out additional MW, however there will be no other source of emissions/fuel burn.

(38) FIGS. 6-8 show various implementations of the embodiment shown in FIG. 1, referred to as the TurboPHASE system. TurboPHASE, which is a supplemental power system for gas turbine systems, is a modular, packaged turbocharger that can be added to most, if not all, gas turbines, and can add up to 20% more output to existing simple cycle and combined cycle plants, while improving efficiency (i.e. heat rate) by up to 7%. The TurboPHASE system is compatible with all types of inlet chilling or fogging systems, and when properly implemented, will leave emissions rates (e.g. ppm of NOx, CO, etc.) unchanged, while the specific emissions rates should improve as the result of improvement in heat rate. Since only clean air, at the appropriate temperature, is injected into the turbine, the TurboPHASE system has no negative effect on gas turbine maintenance requirements. Due to the factory-assembled & tested modules that make up the TurboPHASE system, installation at an existing power plant is quick, requiring only a few days of the gas turbine system being down for outage to complete connections and to perform commissioning.

(39) FIG. 6 shows an implementation of the embodiment of the present invention shown in FIG. 1 in conjunction with two 135 MW General Electric Frame 9E industrial gas turbines 82, 84 in a combined cycle configuration with a 135 MW steam turbine 86 (ST). The results of this implementation are shown below in Table 1.

(40) TABLE-US-00001 TABLE 1 (7.0% additional Flow added to 2 1 9E combined cycle on a 59 F. day (71 lbs/sec GT)) Existing plant With TurboPHASE Compressor Pressure ratio 12.7 13.6 Compressor discharge temperature 673 F. 760 F. Compressor discharge pressure 185 psi 197 psi Turbine firing temperature 2035 F. 2035 F. Turbine exhaust temperature 1000 F. 981 F. (19 F.) 9E GT Output (MW each) 135 MW (base load each) +23 MW (+17% output) Increased Flow N/A +20.7 Increase PR turbine output (delta) N/A +5.6 Increase PR compressor load (delta) N/A 3.3 ST Output (MW) 135 MW (base load) +16 MW (+12%) Increased Flow N/A +9.4 Cooler Exhaust Temperature N/A 2.9 Jacket Heat and IC Heat put into ST N/A +9.9 9E Plant Output SC (MW) 135 MW (base load) 158 MW (+23 MW or +17%) 9E Plant Output CC (MW) 405 MW (base load) 467 MW (+62 MW or +15%) Base Load Fuel Burn per GT 1397 MMBTU/hr 1514 MMBTU/hr Fuelburn of aux engine delivering 71 N/A 96 MMBTU/hr (740 Gal/hr ~15,000 hp) lb/sec Total additional fuelburn of GT N/A 11 MMBTU/hr (+1%) Increase Fuel Flow N/A 98 MMBTU/hr (+7%) Increased PR/higher N/A 77 MMBTU/hr CDT/mixed temp Total Plant Fuelburn CC 2974 MMBTU/hr 3028 MMBTU/hr Heatrate SC 10350 BTU/kWh 9582 BTU/kWh (767 BTU/kWh or 7%) Heatrate CC 6900 BTU/kWh 6483 BTU/kWh (416 BTU/kWh or 6%)

(41) As is clear from Table 1, the implementation increased power output from each of the gas turbines by 23 MW, and increased power output from the steam turbine by 6 MW, for a total of 52 MW (223 MW+6 MW=52 MW). The TurboPHASE system increases air flow to the gas turbines by 7%, is operable at any ambient temperature, and yields a 4% heat rate improvement. In doing so, the pressure ratio (PR) at the gas turbine outlet of each gas turbine increased by 5.6, while the PR of the compressor load exhibited a 3.3 decrease. The total fuel consumption rate for the combined cycle (CC) plant increased by 54 MMBTU/hr while the heat rate for the CC plant decreased by 416 BTU kWh. For informational purposes, Table 1 also shows that if the implementation had been on a simple cycle (SC) plant, the increased power output from each of the gas turbines by would have totaled 46 MW, while the heat rate would have decreased by 767 BTU/kWh. As an option, the intercooler heat exchanger can be eliminated and the supplemental compressor heat and engine heat added to the steam turbine cycle, which increases ST output from +6 MW to +16 MW (62 MW total) and improves heat rate by 6%.

(42) FIG. 7 shows an implementation of the embodiment shown in FIG. 1 on a CC plant comprising one General Electric Frame 9FA industrial gas turbine 82 and one 138 MW steam turbine. In this implementation, power output by the 9FA industrial gas turbine 82 is increased by 42 MW from 260 MW, and power output by the steam turbine 88 is increased by 8 MW, for a total power output increase of 50 MW, along with a heat rate improvement of 0.25%. As an option, the intercooler heat exchanger 28 can be eliminated and the heat of compression of the supplemental compressor 22 and the heat from the exhaust 32 of the fueled engine can be added to the H SG in the steam cycle, which increases ST output from +8 MW to +14 MW (56 MW total) and improves heat rate to 1.8%.

(43) FIG. 8 shows an implementation of the embodiment shown in FIG. 1 on a SC plant comprising one General Electric Frame 9B (or 9E) industrial gas turbine 90. In this implementation, power output by the 9B is increased by 23 MW from 135 MW, along with a heat rate improvement of 7%.

(44) Implementation of the embodiments of the present invention preferably provide the following benefits: (i) Installation is quick and simple, with no major electric tie-in required; (ii) No change in gas turbine firing temperature, so gas turbine maintenance costs are unchanged; (iii) It uses existing ports on gas turbine system's combustion case to inject air; (iv) High efficiency, recuperated and internal combustion engine-driven inter-cooled supplemental compressor improves both SC and CC heat rates; (v) It is compatible with water injection, fogging, inlet chilling, steam injection, and duct burners; (vi) Air is injected into gas turbine combustion case at compatible temperatures and pressures; (vii) The internal combustion, reciprocating, fueled engine can burn natural gas, low BTU biofuel or diesel (also available with small steam turbine driver and small gas turbine driver for the fueled engine.); and (viii) Energy storage option also available: approximately 2 times the price and 2 times the efficiency improvement.

(45) Referring now to FIG. 9, a further embodiment of the present invention relates to enhancements for providing additional power to a gas turbine engine 1 as well as additional power external to the gas turbine engine 1. A typical gas turbine engine 1 has an axial compressor 10, a combustion system 12 consisting of one or more combustors, a compressor discharge plenum 14, a turbine 16 and a generator 18. The gas turbine engine 1 compresses air 20, adds fuel 24, and ignites the mixture to generate hot gasses 22 passing through the turbine 16, where the turbine 16 drives the compressor 10 and the generator 18 through shaft A.

(46) The present invention also comprises a power augmentation system 120 having a fueled engine 151 that generates shaft power for driving an intercooled compressor 116, also referred to interchangeably herein as a supplemental compressor. The intercooled compressor 116 takes ambient air 115, compresses the air 115, and yields a relatively cool compressed air 117 exiting the intercooled compressor 116. The compressed air 117 is later heated in a recuperator 171, resulting in heated compressed air 141, which is then injected into the gas turbine engine 1 when the injection control valve 142 is open. The compressed air 117 passing through the recuperator 171 is heated by heat transferred from the exhaust 152 of the fueled engine 151, which is driving the intercooled compressor 116. That is, the fueled engine 151, operating on a diesel or natural gas fuel 124 produces mechanical power and, as a by-product, heat exhaust. This heated exhaust 152 passes through the recuperator 171, and due to the heat exchange process occurring in the recuperator 171, the compressed air 117 is heated, resulting in heated compressed air 141 and a warm exhaust 153 exiting the recuperator 171 after some of the energy is transferred to the compressed air 117.

(47) In an alternate embodiment of the present invention, an auxiliary heater 191 can be added to the power augmentation system 120 if air injection temperatures are lower than desired in order to raise the heated air temperature even further prior to injection. The auxiliary heater 191, which can be either an electric or fueled heater, can be positioned between the recuperator 171 and the injection control valve 142, as shown in FIG. 9.

(48) As discussed above, the ambient air 150 is compressed through the intercooled compressor 116. As one skilled in the art understands, an intercooled compressor 116 produces cooled compressed air by passing each stage of compressed air through an intercooler 205. The intercooler 205 has coolant 202 entering the coolers, where the coolant 202 is typically water or water with an additive to keep it from freezing. The coolant temperature is a main component to the efficiency of the intercooled compressor 116. The colder the coolant 202, the more efficient the compression process. Coolant exits the intercooler 205 at a coolant outlet 207.

(49) Referring still to FIG. 9, a motor-generator 181 is coupled to the shaft B which couples the fueled engine 151 to the intercooled compressor 116. The motor-generator can be a standard multi-pole design depending on the speed and frequency of the grid. The motor-generator 181 is coupled to the power augmentation system 120, including the fueled engine 151 and intercooled compressor 116, by way of a clutch. The clutch can be selectively engaged and disengaged as the need for the motor-generator 181 changes. Although automatic type engage/disengage clutches are available like an SSS clutch, it is envisioned that the operation of the system will be for infrequent emergency applications and a manual system on the same SSS clutch can be deployed in these cases. The motor-generator 181 provides numerous benefits to the present invention. First, during times of additional power requirements, the power of the fueled engine 151 can be enhanced by driving the electric motor portion of motor-generator 181 to generate additional pressurized air flow. Additional air flow to the gas turbine engine can provide an incremental increase in electrical power from the power plant to the grid. Second, during times of rapid load fluctuations in load demands, the electric motor portion of the motor-generator 181 and fueled engine 151 can be used in combination to absorb incremental power or to rapidly deliver incremental power. Furthermore, during periods when the power plant needs power electrical power to start up the power plant, the fueled engine 151 can provide mechanical shaft power to drive the motor-generator 181 so as to generate the electrical power to start the power plant.

(50) As one skilled in the art understands, in order to start the gas turbine engine 1, electrical power from the grid is required to help start turning the turbine and compressor of the gas turbine engine 1. Standalone back-up power supplies can be placed at a power plant for starting the power plant when electrical power is not available. However, since these back-up systems are costly and used infrequently, they are an inefficient use of an operator's assets. Coupling a motor-generator 181 to the power augmentation system disclosed herein alleviates the concern of being able to start a power plant without electricity from the grid and does so in a more cost effective manner. That is, coupling the motor-generator 181 to the fueled engine of the power augmentation system 120 forms a standalone back-up power supply for a power plant and provides a way to start the gas turbine engine 1 when there is no grid power available.

(51) The present invention can also eliminate the need for grid power to be available to the power plant when the plant is offline for maintenance. That is, many power plants rely on grid power to provide electricity to the plant when it is down for maintenance. In fact, power plants pay for this capacity to be available to them on a monthly basis. Therefore, by having a power augmentation 120 and motor-generator system 181 disclosed herein, back-up power is available to the power plant when the plant is offline.

(52) Another unique aspect of the present invention is using the fueled engine 151 and motor-generator 181 together to increase the airflow provided to the intercooled compressor 116, compared to the air flow that can be generated by just the intercooled compressor 116 and fueled engine 151. More specifically, for a typical F-class gas turbine power plant, such as a General Electric Frame 7FA gas turbine, the fueled engine 151 can generate about 2 MW of power to the power augmentation system disclosed herein, which results in about an additional 5.5 MW of electricity due to the additional heated compressed air provided from the intercooled compressor 116 to the gas turbine engine 1. Adding the motor-generator 181 can provide an additional 2 MW of power to the drive train, for a total of 4 MW, which would result in approximately an 11 MW increase in power output from the power augmentation system components. However, 2 MW of the 11 MW generated would be consumed by the motor-generator 181, resulting in a net output increase of about 9 MW.

(53) Another benefit of the system disclosed in FIG. 9 is that the fueled engine 151 and motor-generator 181 can be used in parallel to provide extremely fast regulation response for either increasing or decreasing power to the grid. For example, the combination of the electric motor portion of motor-generator 181 and the fueled engine 151 can be used to provide the 2 MW of power necessary to drive the power augmentation system 120, also known as TurboPHASE. The load on the fueled engine 151 can swing from 0% to 100% and the motor-generator 181 can then provide power from 100% to 0% in order to maintain the 2 MW to the power augmentation system, allowing it to operate uninterrupted. Thus, the 2 MW of load swing effectively provides a method to provide 2 MW of high speed regulation capacity which can provide a plant output of 3.5 MW to 5.5 MW without changing anything on the gas turbine engine 1.

(54) As shown in FIG. 9, the heated compressed air 141 can be injected in the gas turbine engine 1 through the injection control valve 142. The injection location shown in FIG. 9 is into the compressor discharge plenum 14, which is fluidly upstream of the one or more combustors 12 of gas turbine engine 1. However, as it will be understood by one of ordinary skill in the art, the point of injection of the heated compressed air 141 could be at other points upstream or downstream of the compressor discharge plenum 14 of the gas turbine engine 1, including components external to the gas turbine engine 1, such as for combined cycle purposes of steam generation or other co-generation needs.

(55) The power augmentation system 120 of the present invention is typically a self-contained system that is configured to be supplied in a container capable of being assembled or disassembled from a power plant with little disruption to existing power plant operations. The container in which the power augmentation system 120 is located may be a permanent fixture added to a power plant or located on site for a temporary time period. The container is sized sufficiently so as to have room for the motor-generator 181 and associated clutch mechanisms.

(56) Referring now to FIG. 10, in an embodiment of the present invention, a method 200 of increasing power output from a gas turbine energy system is disclosed, where the gas turbine energy system has a fueled engine, a supplemental compressor, and a motor-generator coupled together. In a step 202, the fueled engine is operated to generate mechanical power which is to be directed to the supplemental compressor. Then, in a step 204, the motor-generator is operated with electricity from a power grid to produce a mechanical output. In a step 206, the mechanical output from the motor-generator is directed to provide additional mechanical power to the supplemental compressor. Then, in a step 208, the supplemental compressor is operated with the mechanical power from both the fueled engine and the motor generator to generate compressed air. As it can be understood by one skilled in the art, providing additional power to drive the supplemental compressor, compared to the mechanical power available from only the fueled engine, provides additional shaft power for compressing additional air, thereby increasing the compressed air flow output from the supplemental compressor.

(57) In yet another embodiment of the present invention, a method 300 of providing an auxiliary power source is disclosed, where the auxiliary power source is driven by a fueled engine. Referring to FIG. 11, in a step 302, a fueled engine, supplemental compressor, and a motor-generator are provided. In a step 304, the fueled engine is operated to generate mechanical power. Then, in a step 306, one of the supplemental compressor or the motor-generator is selected to receive the mechanical power from the fueled engine. Depending on the drid control signal, a control algorithm can be used to determine which system gets the mechanical power. For example, if the gas turbine is not running, the mechanical power can go to the generator to put power on the grid quickly. If the gas turbine is running, more power can be made with the same mechanical power going to the air compressor, because the air going to the gas turbine results in 2-3 times more power depending on the type of gas turbine. Next, in a step 308, the mechanical power is directed to the supplemental compressor or the motor generator. If the motor-generator is selected to receive the mechanical output from the fueled engine, a clutch is engaged such that the shaft powered by the fueled engine then drives the motor-generator. Then, in a step 310, the supplemental compressor or the motor-generator is operated with mechanical power from the fueled engine, and in a step 312, output, in the form of auxiliary power, such as compressed air source, electrical output, or additional mechanical power, is output from the compressor or the motor-generator.

(58) While the invention has been described in what is known as presently the preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment but, on the contrary, is intended to cover various modifications and equivalent arrangements within the scope of the following claims. The present invention has been described in relation to particular embodiments, which are intended in all respects to be illustrative rather than restrictive.

(59) From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects set forth above, together with other advantages which are obvious and inherent to the system and method. It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and within the scope of the claims.