Combined cycle power plant with exhaust gas recirculation intercooling

Abstract

The combined cycle power plant (100) provides a gas turbine engine (102) including a compressor (106) having a compressor inlet (168), a compressor outlet (170), and an intermediate stage inlet (172) defined therebetween. 【Solution means】The turbine (110) also includes a turbine outlet configured to discharge a first exhaust gas flow (112) therefrom. The heat recovery steam generator (114) is configured to receive the first exhaust gas flow (112), extract heat from the first exhaust gas flow (112), and discharge a second exhaust gas flow (120) therefrom. The recirculation compressor (404) pressurizes a first portion of the second exhaust gas flow (120) and recirculates it towards the compressor intermediate stage inlet (172), or the admission compressor (174) pressurizes an air flow towards the compressor intermediate stage inlet (172). The first cooler (148) cools an air flow directed towards the compressor (106), thereby defining a cooled air flow (180), and the first cooler (148) provides the cooled air flow (180) to the intermediate stage inlet (172) of the compressor (106).

Description

Technical Field

[0001] The present disclosure generally relates to power generation systems, and more specifically to systems that use cooling air or recirculated exhaust gas for compressor intercooling.

Background Art

[0002] Gas turbine systems are used to generate electricity and typically include a compressor, a combustor, and a turbine. Operating a gas turbine system at a higher operating temperature generally improves performance, efficiency, and output. Therefore, during operation, components in various gas paths within the system may be exposed to high-temperature flows. Continued exposure to high-temperature flows over a long period of time can cause excessive loads on the components or shorten their service life. Accordingly, at least some of the gas turbine components known to be exposed to high-temperature airflows are cooled, enabling the gas turbine system to continue operating at high temperatures. For example, for cooling purposes, some components may be supplied with compressor bleed air or the like. However, air that is compressed by the compressor and not used to generate combustion gas generally reduces the overall efficiency of the gas turbine system.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] In one aspect, a combined cycle power plant is provided that includes a gas turbine engine including a compressor having a compressor inlet, a compressor outlet, and an intermediate stage inlet defined therebetween, and a turbine outlet directed to discharge a first exhaust gas stream therefrom. A heat recovery steam generator receives the first exhaust gas stream therein, extracts heat from the first exhaust gas stream, and discharges a second exhaust gas stream therefrom. A recirculation compressor pressurizes a first portion of the second exhaust gas stream toward the compressor for recirculation, and a first cooler cools the first portion of the second exhaust gas stream after compression, thereby defining a cooled exhaust gas stream, and the first cooler discharges the cooled exhaust gas stream to the intermediate stage inlet of the compressor.

[0005] In another aspect, a gas turbine assembly is provided that includes a gas turbine engine. The gas turbine engine includes a compressor having a compressor inlet, a compressor outlet, and an intermediate stage inlet defined therebetween. The gas turbine engine further includes a turbine outlet directed to discharge a first exhaust gas stream therefrom. An admission compressor pressurizes the flow toward the compressor. A first cooler cools the compressed flow discharged from the admission compressor, thereby defining a pressurized and cooled flow, and the first cooler discharges the pressurized and cooled flow to the intermediate stage inlet of the compressor.

[0006] In a further aspect, a combined cycle power plant is provided that includes a gas turbine engine including a compressor having a compressor inlet, a compressor outlet, and an intermediate stage inlet defined therebetween, and a turbine outlet configured to discharge a first exhaust gas stream therefrom. A heat recovery steam generator receives the first exhaust gas stream therein, extracts heat from the first exhaust gas stream, and discharges a second exhaust gas stream therefrom. At least one of a recirculation compressor that pressurizes a first portion of the second exhaust gas stream for recirculation toward the compressor and an admission compressor that pressurizes an ambient air stream toward the compressor. A first cooler cools at least one of the ambient air stream or the first portion of the second exhaust gas stream, thereby defining a cooled exhaust gas stream, and the first cooler discharges the cooled exhaust gas stream to the intermediate stage inlet of the compressor.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0008] The embodiments described herein relate to a power generation system that uses injected cooling air or recirculated exhaust gas for compressor intercooling. Exhaust gas recirculation has conventionally been supplied to the inlet of a gas turbine, but in the system described herein, the recirculated exhaust gas is compressed so that it can flow to the inter-stage compressor inlet after the gas has been cooled. This effectively transforms a simple Brayton cycle engine into an engine with an intercooler. Alternatively, pressurized and cooled ambient air may be supplied to the compressor intermediate stage intake.

[0009] The advantages of introducing cooled ambient air or recirculated exhaust gas into the inter-stage intake of the compressor of a gas turbine include the following. a) The introduction of the cooled flow results in a temperature drop of the working fluid and a drop in the compressor outlet temperature, which increases the output, and the combination enables more fuel to be burned. Combustion becomes possible. b) The physical size of the exhaust gas recirculation piping / duct is reduced, enabling recirculation to the compressor inlet, thus reducing costs and facilitating the routing of the exhaust line. c) The gas temperature in the compressor and at the compressor discharge decreases, the rotor temperature decreases, and the service life of the gas turbine rotor and high-temperature gas path components is extended. d) By flowing outside air that has passed through an aftercooler rather than exhaust gas through the boost compressor, it is useful in a conventional gas turbine combined cycle system that does not use exhaust gas recirculation, particularly for engines with a limit on compressor discharge volume and / or turbines operating in an environment where high-temperature output is beneficial.

[0010] Unless otherwise indicated, approximate expressions such as "substantially", "essentially", "about", etc. used in this specification indicate that the term may apply only to an approximate degree, not to an absolute or perfect degree, as would be recognized by a person skilled in the art. Thus, a value modified by terms such as "about", "substantially", "essentially" is not limited to the specifically stated exact value. In at least some instances, the approximate expression may correspond to the accuracy of the instrument used to measure the value. Further, unless otherwise specified, terms such as "first", "second", etc. are used in this specification merely as labels and are not intended to impose an order, position, or hierarchical requirement on the items they refer to. Further, a reference to a "second" item does not require or exclude the existence of a "first" or smaller-numbered item, or a "third" or larger-numbered item.

[0011] FIG. 1 is a schematic diagram of an exemplary combined cycle power plant 100. In an exemplary embodiment, the power plant 100 includes a gas turbine assembly 102 and a steam turbine 104. The gas turbine assembly 102 includes a compressor 106, a combustor 108, and a turbine 110 coupled in a series flow relationship. During operation, the combustor 108 receives air from the compressor section 106, receives fuel from a fuel supply, mixes the fuel and air to produce a fuel-air mixture, and burns this mixture to produce combustion gases. The combustion gases flow through the turbine 110 and are discharged from the turbine 110 as a first exhaust gas stream 112. In an exemplary embodiment, the power plant 100 also includes a steam cycle device including a heat recovery steam generator (HRSG) 114 and a steam turbine 104. In some embodiments, the steam cycle device may also include other components including a condenser 116 and at least one circulation pump 117. Further, in other embodiments, the steam cycle device may also include at least one additional HRSG 114.

[0012] In an exemplary embodiment, the HRSG 114 includes an inlet 118 that receives the first exhaust gas stream 112 from the gas turbine assembly 102. Heat is extracted from the first exhaust gas stream 112, and a second exhaust gas stream 120 is discharged from a first outlet 122. The second exhaust gas stream 120 is at a lower temperature than the temperature of the first exhaust gas stream 112 entering the inlet 118. The HRSG 114 also includes a second outlet 124 that discharges a first steam stream 126. The steam turbine 104 receives the first steam stream 126 and then discharges an intermediate extraction stream 128 therefrom. The steam that is not extracted in the stream 128 continues to expand until it condenses in the condenser 116. In some embodiments, the steam turbine 104 may include an additional steam inflow from the HRSG 114. In an exemplary embodiment, the gas turbine assembly 102 and the steam turbine 104 are coupled to a generator 132 that generates electricity using a working fluid flowing through each. Alternatively, the turbine assembly 102 and the steam turbine 104 may be on separate shafts, each coupled to a separate generator.

[0013] In an exemplary embodiment, the power plant 100 also includes a carbon capture system 134. During operation, the carbon capture system 134 produces a carbon dioxide stream 138. The carbon capture system 134 can include one or more separators that are used alone or in combination with other separation processes such as carbon dioxide selective membrane technologies, absorption processes, diaphragms. The exhaust stream or the carbon-removed exhaust stream 140 may be discharged from the carbon capture system 134 to the ambient environment. The exhaust stream 140 may be further processed before being discharged to the environment or elsewhere. At least a portion of the carbon dioxide stream 138 may be pressurized, for example, to supercritical pressure for transportation and / or storage.

[0014] The carbon dioxide recovery system 134 generally includes an absorber 142, a stripper 144, and a stripper reboiler 146. During operation, the second exhaust gas stream 120 discharged from the HRSG 114 flows towards the absorber 142. The exhaust gas may be pre-treated to remove impurities such as particulate matter, SOx, and NOx before entering the absorber 142. Further, in an exemplary embodiment, a first cooler 148 is coupled between the HRSG 114 and the carbon recovery system 134. Alternatively, the carbon recovery system 134 may include at least one booster blower (not shown) for pressurizing the flow towards the carbon recovery system 134. The first cooler 148 may be, but is not limited to, a quench tower. The first cooler 148 cools a portion of the second exhaust gas stream 120 and directs it towards the carbon recovery system 134. A solvent 152 rich in carbon dioxide is discharged from the absorber 142 and sent to the stripper 144 via a pump 154. A solvent 156 lean in carbon dioxide is discharged from the stripper 144 and returned to the upper portion of the absorber 142 via the reboiler 146, a pump 166, and a heat exchanger 158. The absorber 142 can be of any typical structure for gas-liquid contact and absorption. The absorber 142 and the stripper 144 can incorporate various internal components such as, for example, trays, packing, and / or supports. In one embodiment, the absorber 142 absorbs carbon dioxide by countercurrent flow from the incoming exhaust gas. The stripper 144 removes carbon dioxide from the solvent 152. The absorber 142 and the stripper 144 can be of various sizes based on the amount of carbon dioxide to be removed and can be sized according to various engineering design equations. Further, a single stripper 144 may serve multiple absorbers 142 and may be coupled thereto.

[0015] The solvent is typically a solution or dispersion of one or more absorbent compounds. More specifically, the solvent is any compound that, when mixed with water, gives rise to an absorbent fluid that increases the ability of the fluid to preferentially remove carbon dioxide from the exhaust gas as compared to the case of water alone. For example, the solvent is monoethanolamine (MEA), but is not limited thereto. Inhibitors may be included in the solvent to suppress the decomposition of the solvent.

[0016] In an exemplary embodiment, the solvent 152 is preheated with respect to the solvent 156 in a countercurrent heat exchanger 158 and then sent to the stripper 144. The stripper 144 is a pressurizing unit, and carbon dioxide is recovered from the solvent 152. The stripper 144 generally incorporates a reboiler 146 and receives a portion of the solvent 156 exiting the stripper 144. The reboiler 146 evaporates the solvent 156 and returns the solvent vapor 160 to the stripper 144 to facilitate the separation of carbon dioxide. One stripper may be coupled to a plurality of reboilers 146. The reboiler 146 receives steam via the stream 128, such as steam from the steam turbine 104, and performs heating in the reboiler 146.

[0017] The steam 162 exiting the stripper 144 is partially condensed in the condenser 136. The condensed portion of the steam 162 is returned to the stripper 144 as reflux 164. The reflux 164 may be transferred via an accumulator (not shown) and a pump (not shown) before entering the stripper 144. The carbon dioxide stream 138 is taken out of the condenser 136 after compression for transportation and / or storage.

[0018] In an exemplary embodiment, compressor 106 includes an inlet 168, an outlet 170, and an interstage inlet 172 defined therebetween. Power plant 100 includes an admission compressor 174 and a controller 176. Depending on the use in power plant 100, admission compressor 174 may be configured to be used as a recirculation compressor. In an exemplary embodiment, a cooler 178, also known as an aftercooler, is coupled between admission compressor 174 and interstage inlet 172. Cooler 178 cools the pressurized air discharged from compressor 174 to generate a cooled admission stream 180. More specifically, cooler 178 discharges the cooled stream 180 toward interstage inlet 172 to improve the performance of plant 100 as described herein.

[0019] However, the power consumption due to the operation of the booster blower and / or compressor 174 reduces the plant output. The intermediate cooling provided to compressor 106 by compressor 174 and its aftercooler 178 promotes the improvement of the output of power plant 100 by reducing the compression work in compressor 106 and enabling more fuel to be burned in combustor 108.

[0020] For example, the controller 176 may monitor the power consumption of any booster blower and / or compressor 174 (and any large auxiliary device within a particular plant), and also determine, for example, steam cycle losses resulting from the discharge of the steam stream 128 towards the carbon capture system 134. The controller 176 can also dynamically determine the power consumption and steam cycle losses and accordingly adjust the operation of the power plant 100. Thus, in one embodiment, the operation of any booster blower, and / or compressor 174 (and / or any other large auxiliary load) is adjusted by the controller 176, facilitating the improvement of the plant output to a level that overcomes power consumption and steam cycle losses. That is, the controller 176 can selectively modulate the flow of any stream flowing into the compressor 106, as described herein, to improve the output of the power plant. In one exemplary embodiment, the use of cooled injection should increase the output boost of the power plant by at least about 5% to about 10% compared to providing substantially the same exhaust gas flow recirculation at the gas turbine inlet. Further, since the temperature of the compressor exhaust can be more easily controlled, a greater performance improvement is possible on hot days when the temperature of the compressor exhaust is typically a limiting factor in at least some known power generation systems.

[0021] An example of a gas turbine parameter that can be monitored to determine an improvement in gas turbine output is the compressor discharge temperature. In an exemplary embodiment, the power plant 100 includes a sensor (not shown) coupled to the outlet 170 that is used to monitor the temperature of the compressed gas discharged therefrom. The controller 176 can adjust the cooled stream 180 supplied to the intermediate stage inlet 172 to maintain the compressor discharge temperature within a predetermined temperature range. The controller 176 facilitates extending the service life of the components within the power plant 100. Thus, the adjustment of the stream provides an option that can be used by the operator of the power plant 100 when determining a method to optimize the performance of the power plant 100.

[0022] It should be noted that the gas turbine assembly 102 may be used independently of the HRSG 114 and the carbon capture system 134. In other words, the turbine assembly 102 may operate as a simple gas turbine assembly 102 that uses the cooled intermediate air intake provided via the admission compressor 174 and the cooler 178. More specifically, in an exemplary embodiment, when the turbine assembly 102 is used as a single simple cycle gas turbine, the assembly 102 operates using the cooled intermediate stage air introduction and operates without an inlet boost (shown in FIGS. 2 and 3).

[0023] By operating the gas turbine assembly 102 as a simple gas turbine, the need for high-cost rotor alloys and additional cooling air is eliminated, and the use of steel compressor wheels is enabled, especially under operating conditions such as hot days when the compressor outlet air temperature is most likely to be the highest. Furthermore, since the air flow rate is low and the operating temperature of the air entering the cooler 178 is high compared to the heat sink (ambient), the physical size and cost of the cooler 178 are relatively modest compared to known power plant systems used to cool the air at the gas turbine inlet. Additionally, the incoming air reduces the compressor exhaust discharge temperature while promoting a reduction in the work required by the compressor 106, so the incoming air promotes output enhancement.

[0024] FIG. 2 is a schematic diagram of an alternative gas turbine assembly 102 for use with the combined cycle power plant 100 (shown in FIG. 1). Unlike the embodiment of FIG. 1 which illustrates an unboosted gas turbine assembly 102, in the exemplary embodiment of FIG. 2, the gas turbine assembly 102 utilizes an external inlet boost blower 182. More specifically, in the exemplary embodiment, the external air boost blower 182 pressurizes the air flow 188 flowing into the inlet 168 of the compressor 106. The boost blower 182 can be used to supercharge the gas turbine assembly 102, thereby facilitating an improvement or enhancement of the gas turbine output. Further, the combination of the boost blower 182 and the cooled intake air flow 180 supplied to the compressor 106 enables the controller 176 (shown in FIG. 1) to enhance the control of the discharge temperature of the compressor 106, and as a result, increases the potential for enhanced output from the turbine assembly 102.

[0025] FIG. 3 is a schematic diagram of another alternative gas turbine assembly 102 that may be used with the combined cycle power plant 100 (shown in FIG. 1). Unlike the embodiment of FIG. 1 showing the unboosted gas turbine assembly 102 and the embodiment of FIG. 2 showing the external boost blower, in the exemplary embodiment of FIG. 3, the gas turbine assembly utilizes a shaft-driven boost compressor 190. More specifically, in the exemplary embodiment, the turbine assembly includes a shaft-driven, inlet boost compressor 190 that pressurizes the ambient air flow 194 flowing toward the interstage inlet 172 of the compressor 106. Similar to the boost blower 182 (shown in FIG. 2), the compressor 190 may be used to supercharge the gas turbine assembly 102. However, the compressor 190 can provide an increased supercharge flow rate to the gas turbine assembly 102 compared to the boost blower 182. The increased supercharge facilitates improving the output of the gas turbine over that of the boost blower 182. The combination of the compressor 190 and the cooled intake air flow 180 supplied to the compressor 106 allows the controller 176 (shown in FIG. 1) to provide enhanced control of the discharge temperature of the compressor 106, thereby increasing the potential for enhanced output from the turbine assembly 102.

[0026] Any of the gas turbine assemblies shown in FIGS. 1 - 3 may or may not be used with the carbon capture system 134. Further, in some embodiments, any of the gas turbine assemblies 102 described herein may be used with recirculated exhaust gas admission, i.e., compressed aftercooled exhaust flow, rather than compressed aftercooled admission stream 180. In such embodiments, the recirculated exhaust gas may be routed from downstream or upstream of the first cooler.

[0027] FIG. 4 is a schematic diagram of an alternative combined cycle power plant 100 (shown in FIG. 1) that includes a gas turbine assembly 102. The embodiment shown in FIG. 4 is similar to the embodiment shown in FIG. 1, although there are differences noted herein below, and thus the same reference numbers as used in FIG. 1 are used in FIG. 4. In FIG. 4, the plant 100 utilizes exhaust gas recirculation 402 with a post - combustion carbon capture system 134. The exhaust gas recirculation flow 402 is drawn from downstream of the first cooler 148 and flows toward the exhaust gas recirculation compressor 404.

[0028] A cooler 406 is coupled between the recirculation compressor 404 and the intermediate stage inlet 172. The cooler 406 cools the pressurized air discharged from the compressor 404 to produce a cooled suction flow 180. More specifically, the cooler 406 discharges the cooled flow 180 toward the intermediate stage inlet 172 to improve the performance of the plant 100 as described herein. In an exemplary embodiment, since the flow 402 is drawn from downstream of the cooler 148, the exhaust flow is cleaned and cooled, so that the compression force of the recirculation compressor 404 is reduced, and also reduced after cooling which is necessary to facilitate control of the compressor discharge temperature.

[0029] In an exemplary embodiment, when compressed after-cooled air is supplied to the intermediate stage inlet 172, the pressurized air flow 180 is clean, so that the cooler 406 and the admission compressor 404 may be disposed relatively close physically to the cooler 148 such that the pipe diameter and plant cost for the vapor 180 are reduced. In embodiments for retrofitting an existing plant, the compressor 106 may be configured to use the exhaust gas discharged from the compressor 404. In such embodiments, the assembly 102 not only obtains the advantages described above, but also obtains performance advantages generally associated with exhaust gas recirculation, such as incomplete combustion, higher exhaust carbon dioxide emissions, lower nitrous oxide emissions, etc. Further, in an exemplary embodiment, the combination of the operation and pressurization of the gas turbine assembly 102 and the HRSG system 114 facilitates overcoming the draft losses through the cooler or quench tower 148 and the carbon recovery system 134. In other alternative embodiments, a booster fan may be used within the carbon recovery system 134 depending on equipment and plant design constraints and economic considerations.

[0030] FIG. 5 is a schematic diagram of another alternative combined cycle power plant 100 that includes a gas turbine assembly 102. FIG. 6 is a schematic diagram of yet another alternative combined cycle power plant 100 that includes a gas turbine assembly 102. Each alternative embodiment is similar to the embodiment illustrated in FIG. 1, although there are differences as noted below, and thus the same reference numerals as those used in FIG. 1 are used in FIGS. 5 and 6.

[0031] In FIG. 5, the plant 100 utilizes exhaust gas recirculation 402 with a post-carbon capture system 134. Further, in the exemplary embodiment shown in FIG. 5, generally the plant 100 uses a compressed exhaust gas recirculation intake passage with an aftercooler that is directed to the main gas turbine, in combination with exhaust gas recirculation to the gas turbine inlet. More specifically, the exhaust gas recirculation flow 402 is drawn from downstream of the first cooler 148, and a portion 502 is directed towards the exhaust gas recirculation compressor 404. A cooler 406 is coupled between the recirculation compressor 404 and the intermediate stage inlet 172. The cooler 406 cools the pressurized air discharged from the compressor 404 to produce a cooled intake flow 180. More specifically, the cooler 406 discharges the cooled flow 180 towards the intermediate stage inlet 172 in order to improve the performance of the plant 100, as described herein.

[0032] The remaining portion 504 of the exhaust gas recirculation flow 402 drawn from downstream of the cooler 148 flows toward an exhaust gas boost blower 506. The boost blower 506 discharges a pressurized and cooled flow 510 toward the compressor inlet 168. In an exemplary embodiment, since the flow 402 is drawn from downstream of the cooler 148, the exhaust flow is cleaned and cooled. The combination of the exhaust gas recirculation compressor 404 and the exhaust gas blower 506 facilitates maximizing the total flow rate of the exhaust gas recirculation using the existing gas turbine within the plant 100. More specifically, in the exemplary embodiment of FIG. 5, since the exhaust gas boost blower 506 is combined with or paired with the inlet air boost blower 182, the gas turbine compressor 106 can operate at an inlet pressure higher than the ambient or atmospheric pressure such that the power output of the plant is optimized.

[0033] Furthermore, the embodiment shown in FIG. 5 also enables overcoming any losses associated with the extraction of the flow to the carbon capture system 134. More specifically, in the plant embodiment shown in FIG. 5, the plant 100 is sufficiently pressurized such that any plant output losses associated with the operation of the carbon capture system 134 are overcome.

[0034] The embodiment shown in FIG. 6 is similar to the embodiment shown in FIG. 5, except that the exhaust gas recirculation compressor does not draw the exhaust gas recirculation 502 from downstream of the blower 506 before the flow 402 enters the blower 506 as shown in FIG. 5. Such an embodiment simplifies the flow control of the exhaust gas recirculation and, as a result, the compressor 404 and associated piping can be physically placed closer to the turbine assembly 102, which may facilitate reducing the cost of the entire plant.

[0035] The embodiments described herein relate to the introduction of cooled ambient air or recirculated exhaust gas into a gas turbine compressor intake. In conventional exhaust gas recirculation, the gas turbine inlet is heated, as a result of which the density of the flow of working fluid entering the compressor is reduced, and the output of the gas turbine and the plant is reduced. The compressor outlet temperature can also be limited and / or controlled using the cooled intermediate stage intake and control methods described herein. Accordingly, the embodiments described herein facilitate output enhancement, reduction of the physical size of the exhaust recirculation piping / ducts, and reduction of the gas temperature within and at the discharge of the compressor.

[0036] A further aspect of the present disclosure is provided by the subject matter of the following clauses. [Embodiment 1] A combined cycle power plant including a gas turbine engine, the gas turbine engine comprising a compressor having a compressor inlet, a compressor outlet, and an interstage inlet defined therebetween, the gas turbine engine further comprising a turbine outlet configured to discharge a first exhaust gas stream therefrom, and a heat recovery steam generator configured to: receive the first exhaust gas stream therein; extract heat from the first exhaust gas stream; discharge a second exhaust gas streamand discharge a second exhaust gas stream therefrom), and a recirculation compressor configured to selectively pressurize a first portion of the second exhaust gas stream for recirculation towards the compressor, and a first cooler configured to cool the first portion of the second exhaust gas stream after compression, thereby defining a cooled exhaust gas stream, wherein the first cooler discharges the cooled exhaust gas stream to the interstage inlet of the compressor, a combined cycle power plant.; [Embodiment 2] A steam turbine configured to discharge a steam stream therefrom, a carbon capture system configured to receive the steam stream, and a controller. The controller is configured to monitor power consumption of the recirculation compressor, determine steam cycle losses resulting from channeling the steam stream towards the carbon capture system, and modulate the flow and temperature of the first portion of the second exhaust gas stream recirculated towards the compressor to facilitate increasing the output of the combined cycle power plant, as described in any of the preceding embodiments. [Embodiment 3] Further comprising a controller, the controller being configured to perform: monitoring a temperature of a compressor discharge stream at the compressor outlet; and modulating the flow of cooled exhaust gas provided to the interstage inlet to facilitate maintaining the temperature of the compressor discharge stream within a predefined temperature range; a combined cycle power plant according to any of the preceding embodiments. [Embodiment 4] Further comprising an exhaust gas recirculation line configured to channel a second portion of the second exhaust gas stream towards the compressor inlet; a combined cycle power plant according to any of the preceding embodiments. [Embodiment 5] Further comprising a splitter configured to separate the second exhaust gas stream into the first portion, the second portion, and a third portion, the splitter sized to define the first portion from between about 5% to about 10% of the second exhaust gas system, the second portion from less than about 40% of the second exhaust gas stream, and the third portion from a remainder, by mass of the second exhaust gas stream, a combined cycle power plant according to any of the preceding embodiments. [Embodiment 6] Further comprising a carbon capture system configured to receive the third portion of the second exhaust gas stream, a combined cycle power plant according to any of the preceding embodiments. [Embodiment 7] A combined cycle power plant according to any one of the preceding embodiments, further comprising a second cooler between the heat recovery steam generator and the carbon capture system, the second cooler being configured to cool a third portion of the second exhaust gas stream directed towards the carbon capture system. [Embodiment 8] A combined cycle power plant according to any one of the preceding embodiments, further comprising an exhaust gas boost blower configured to channel the second exhaust gas stream towards a recirculation compressor, and a splitter configured to separate the second exhaust gas stream discharged from the exhaust gas boost blower into a first portion directed towards the recirculation compressor and a second portion directed towards the compressor inlet. [Embodiment 9] A gas turbine assembly including a gas turbine engine, the gas turbine engine including a compressor having a compressor inlet, a compressor outlet, and an interstage inlet defined therebetween, the gas turbine engine further including a turbine outlet configured to discharge a first exhaust gas stream therefrom, an admission compressor configured to pressurize one of an exhaust gas stream for recirculation towards the compressor and an ambient air stream channeled towards the compressor, and a first cooler configured to cool the compressed flow discharged from the admission compressor, thereby defining a pressurized cooled stream, the first cooler discharging the pressurized cooled stream to the interstage inlet of the compressor, gas turbine assembly. [Embodiment 10] The gas turbine assembly according to any of the preceding embodiments, further comprising an external inlet boost blower configured to selectively pressurize an ambient airflow stream prior to the airflow stream being discharged towards the compressor inlet. [Embodiment 11] The gas turbine assembly according to any of the preceding embodiments, further comprising an inlet boost compressor rotatably coupled to the compressor, the inlet boost compressor configured to pressurize an ambient airflow stream discharged towards the compressor inlet. [Embodiment 12] Further including a controller, the controller is configured to perform the steps of: monitoring a temperature of a compressor discharge stream at the compressor outlet; and modulating at least one of the flow and a temperature of the cooled stream provided to the compressor interstage inlet to facilitate maintaining the temperature of the compressor discharge stream within a predefined temperature range. The gas turbine assembly according to any one of the preceding embodiments. [Embodiment 13] The gas turbine assembly according to any one of the preceding embodiments, further including one of: an external inlet boost blower configured to selectively supercharge the gas turbine assembly; and a shaft-driven inlet boost compressor configured to selectively supercharge the gas turbine assembly. [Embodiment 14] A combined cycle power plant including a gas turbine engine, wherein the gas turbine engine includes a compressor having a compressor inlet, a compressor outlet, and an interstage inlet defined therebetween, and the gas turbine engine further includes a turbine outlet configured to discharge a first exhaust gas stream therefrom, and a heat recovery steam generator configured to receive the first exhaust gas stream therein, extract heat from the first exhaust gas stream, and discharge a second exhaust gas stream therefromand discharging a second exhaust gas stream therefrom), and a recirculation compressor configured to selectively pressurize a first portion of the second exhaust gas stream for recirculation towards the compressor, and either an admission compressor configured to pressurize an ambient airflow stream towards the compressor, and a first cooler configured to cool at least one of the ambient airflow stream or the first portion of the second exhaust gas stream after compression, thereby defining a cooled exhaust gas stream, wherein the first cooler discharges the cooled exhaust gas stream to the interstage inlet of the compressor.; [Embodiment 15] an ambient airflow blower configured to pressurize an ambient airflow stream channeled towards the compressor inlet, a steam turbine configured to discharge a steam stream therefrom, a carbon capture system configured to receive the steam stream, and a controller. The controller monitors power consumption of one of the recirculation compressor and the admission compressor, determines steam cycle losses resulting from discharging the steam stream towards the carbon capture system, and modulates the flow of at least one of the ambient airflow stream or the first portion of the second exhaust gas stream channeled towards either the compressor or the ambient airflow blower pressurizing an to pump the ambient airflow towards the compressor and facilitate increasing the output of the combined cycle power planta combined cycle power plant according to any one of the preceding embodiments, configured to perform (an ambient airflow stream towards the compressor to facilitate increasing the output of the combined cycle power plant). [Embodiment 16] a combined cycle power plant according to any one of the preceding embodiments, further comprising a controller configured to perform a step of monitoring a compressor discharge temperature at the compressor outlet and a step of modulating at least one of the flow and a temperature of one of the cooled recirculated exhaust gas provided to the compressor interstage inlet or the cooled ambient airflow stream provided to the interstage inlet to facilitate maintaining the compressor discharge temperature within a predefined temperature range. [Embodiment 17] The combined cycle power plant according to any of the preceding embodiments, further comprising an exhaust gas recirculation line configured to channel the second exhaust gas stream towards the compressor inlet. [Embodiment 18] The combined cycle power plant according to any of the preceding embodiments, further comprising a splitter configured to separate the second exhaust gas stream into the first portion, the second portion, and a third portion, the splitter sized to define the first portion from between about 5% to about 10% of the second exhaust gas stream, the second portion from less than about 40% of the second exhaust gas stream, and the third portion from a remainder, by mass of the second exhaust gas stream. [Embodiment 19] The combined cycle power plant according to any of the preceding embodiments, further comprising a carbon capture system configured to receive the third portion of the second exhaust gas stream. [Embodiment 20] The combined cycle power plant according to any of the preceding embodiments, further comprising a second cooler located upstream from the splitter.

[0037] The foregoing description is for illustrative purposes only, and those skilled in the art will recognize that modifications can be made to the described embodiments without departing from the scope of the disclosed invention. Modifications within the scope of the present invention will become apparent to those skilled in the art upon review of the present disclosure. Such modifications are intended to be included within the scope of the appended claims. The systems and methods described herein are not limited to the specific embodiments described herein, but rather, the various system components may be utilized separately and independently from the other systems and components described herein. For example, the introduction of a cooled intermediate stage can be implemented and utilized in connection with any application where enhanced output is desired.

[0038] Although shown in some of the drawings, it may not be shown in other drawings, this is for convenience only. Further, the reference to "one embodiment" in the foregoing description is not intended to be construed as excluding the existence of additional embodiments that also incorporate the described features. In accordance with the principles of this specification, any feature of a drawing may be referenced and / or claimed in combination with any feature of another drawing.

[0039] Although the present invention has been described with respect to various specific embodiments, those skilled in the art will recognize that modifications can be made and implemented within the spirit and scope of the claims.

Explanation of Signs

[0040] 100: Combined cycle power plant 102: Gas turbine assembly 104: Steam turbine 106: Compressor 108: Combustor 110: Turbine 112: First exhaust gas stream 114: Heat recovery steam generator (HRSG) 116: Condenser 117: Circulation pump 118: Inlet 120: Second exhaust gas stream 122: First outlet 124: Second outlet 126: First steam stream 128: Intermediate extraction stream 132: Generator 134: Carbon capture system 134 is a carbon dioxide stream 138: Carbon dioxide stream 140: Exhaust stream 142: Absorber 144: Stripper 146: Stripper reboiler / reboiler 148: First cooler 152: Solvent rich in carbon dioxide 154: Pump 156: Solvent lean in carbon dioxide 158: Heat exchanger / countercurrent heat exchanger 160: Solvent vapor 162: Steam 164: Reflux 166: Pump 168: Inlet 170: Outlet 172: Intermediate stage inlet 174: Admission compressor 176: Controller 178: Cooler / aftercooler 180: Cooled intake stream / compressed aftercooler inflow stream 182: External inlet booster blower / external air booster blower / booster blower 188: Air stream 190: Shaft-driven booster compressor / shaft-driven inlet booster compressor 194: Ambient air stream 402: Exhaust gas recirculation stream 404: Exhaust gas recirculation compressor 406: Cooler 502: Part / exhaust gas recirculation 504: Remaining part 506: Exhaust gas booster blower 510: Pressurized and cooled stream

Claims

1. A combined cycle power plant (100) including a gas turbine engine (102), wherein the gas turbine engine includes a compressor (106) having a compressor inlet (168), a compressor outlet (170), and an intermediate stage inlet (172) defined therebetween, and the gas turbine engine (102) further includes a turbine (110) outlet configured to discharge a first exhaust gas stream therefrom, a heat recovery steam generator (114) configured to receive the first exhaust gas stream (112), extract heat from the first exhaust gas stream (112), and discharge a second exhaust gas stream (120), a recirculation compressor (404) configured to selectively pressurize a first portion of the second exhaust gas stream (120) and recirculate it toward the compressor (106), and a first cooler (148) configured to cool the first portion of the second exhaust gas stream (120), wherein the first cooler (148) discharges a cooled exhaust gas stream (180) to the intermediate stage inlet (172) of the compressor (106). A combined cycle power plant (100).

2. Further including a steam turbine (104) configured to discharge a steam stream (128) therefrom, a carbon capture system (134) configured to receive the steam stream (128), and a controller (176), wherein the controller (176) monitors the power consumption of the recirculation compressor (404), determines the steam cycle loss by directing the steam stream (128) toward the carbon capture system (134), and adjusts the flow and temperature of the first portion of the second exhaust gas stream recirculated toward the compressor to facilitate increasing the output of the combined cycle power plant. The combined cycle power plant (100) according to Claim 1, which is configured to perform the steps of

3. Further including a controller (176), wherein the controller (176) monitors the temperature of the compressor discharge fluid at the compressor outlet (170), and adjusts the flow rate of the cooled exhaust gas (180) supplied to the intermediate stage inlet (172) to facilitate maintaining the temperature of the compressor discharge fluid within a predetermined temperature range. The combined cycle power plant (100) according to Claim 1, which is configured to perform the steps of

4. The combined cycle power plant (100) according to claim 1, further comprising an exhaust gas recirculation (402) line configured to flow the second portion of the second exhaust gas stream (120) towards the compressor inlet (168).

5. The combined cycle power plant (100) according to claim 4, further comprising a splitter configured to separate the second exhaust gas stream (120) into a first portion, a second portion, and a third portion, the splitter sizing the first portion between about 5% and about 10% of the second exhaust gas system, the second portion less than about 40% of the second exhaust gas stream (120), and the third portion the remaining portion, as defined by the mass of the second exhaust gas stream (120).

6. The combined cycle power plant (100) according to claim 5, further comprising a carbon capture system (134) configured to receive the third portion of the second exhaust gas stream (120).

7. The combined cycle power plant (100) according to claim 6, further comprising a second cooler (178) between the heat recovery steam generator (114) and the carbon capture system (134), the second cooler (178) being configured to cool the third portion of the second exhaust gas stream (120) towards the carbon capture system (134).

8. The combined cycle power plant (100) according to claim 1, further comprising an exhaust gas boost blower (506) configured to flow the second exhaust gas stream (120) towards the recirculation compressor (404), and a splitter configured to separate the second exhaust gas stream (120) discharged from the exhaust gas boost blower (506) into a first portion towards the recirculation compressor (404) and a second portion towards the compressor inlet (168).

9. A gas turbine assembly (102) including a gas turbine engine (102), the gas turbine engine including a compressor (106) having a compressor inlet (168), a compressor outlet (170), and an intermediate stage inlet (172) defined therebetween, the gas turbine engine (102) further including a turbine (110) outlet configured to discharge a first exhaust gas flow (112) therefrom, an admission compressor (174) configured to pressurize either an exhaust gas flow (402) recirculating toward the compressor (106) or an ambient air flow (194) directed toward the compressor (106), and a first cooler (148) configured to cool the compressed flow discharged from the admission compressor (174), thereby defining a pressurized and cooled flow, the gas turbine assembly (102) wherein the first cooler (148) discharges the pressurized and cooled flow (180) to the intermediate stage inlet (172) of the compressor (106).

10. The gas turbine assembly according to claim 9, further comprising an external inlet boost blower (182) configured to selectively boost the ambient air flow (194) before the air flow (194) is discharged toward the compressor inlet (168).

11. The gas turbine assembly according to claim 9, further comprising an inlet boost compressor (190) rotatably coupled to the compressor (106), the inlet boost compressor (190) being configured to increase the pressure of the ambient air flow (194) discharged toward the compressor inlet (168).

12. The gas turbine assembly according to claim 9, further comprising a controller configured to monitor the temperature of the compressor discharge flow at the compressor outlet (170) and to adjust at least one of the flow rate and temperature of the cooled fluid (180) supplied to the compressor intermediate stage inlet (170) to facilitate maintaining the temperature of the compressor discharge flow within a predetermined temperature range.

13. An external inlet boost blower (182) configured to selectively supercharge the gas turbine assembly (102), and a shaft-driven inlet boost compressor (190) configured to selectively supercharge the gas turbine assembly (102), the gas turbine assembly according to claim 9, further comprising one of them.

14. A combined cycle power plant (100), A gas turbine engine (102) comprising a compressor (106) having a compressor inlet (168), a compressor outlet (170), and an intermediate stage inlet (172) defined therebetween, and further comprising a turbine (110) outlet configured to discharge a first exhaust gas stream (112) therefrom. A heat recovery steam generator (114) configured to receive the first exhaust gas stream (112), extract heat from the first exhaust gas stream (112), and discharge a second exhaust gas stream (120) therefrom. At least one of a recirculation compressor (404) and an admission compressor (174), The recirculation compressor (404) is configured to selectively pressurize a first portion of the second exhaust gas stream (120) and recirculate it towards the compressor (106). The admission compressor (174) is configured to pressurize an ambient air stream (194) towards the compressor (106), at least one of the recirculation compressor (404) and the admission compressor (174). A first cooler (148) configured to cool at least one of the ambient air stream (194) or a first portion of the second exhaust gas stream (120) after compression, thereby defining a cooled exhaust gas stream (180), and the first cooler (148) discharges the cooled exhaust gas stream (180) to the intermediate stage inlet (172) of the compressor (106). A controller configured to regulate at least one of the ambient air stream or a first portion of the second exhaust gas stream, and pressurize the ambient air stream flowing towards either the compressor or the ambient air blower, promoting an increase in the output of the combined cycle power plant (100).

15. A steam turbine (104) configured to discharge a steam flow (128) therefrom, a carbon capture system (134) configured to receive the steam flow (128), and a controller (176), further comprising, wherein the controller (176) monitors the power consumption of one of the recirculation compressor (404) and the admission compressor (174), The combined cycle power plant (100) according to claim 14, wherein the combined cycle power plant (100) is configured to determine a steam cycle loss caused by discharging the steam flow (128) toward the carbon capture system (134).

16. Further comprising a controller (176), wherein the controller (176) monitors the discharge temperature of the compressor (106) at the compressor outlet (170), The combined cycle power plant (100) according to claim 14, further comprising a controller (176) configured to adjust at least one of the flow rate and temperature of at least one of the cooled recirculation exhaust gas (180) supplied to the intermediate stage inlet (172) of the compressor or the cooled ambient air flow (194) supplied to the intermediate stage inlet (172) of the compressor to facilitate maintaining the discharge temperature of the compressor within a predetermined temperature range.

17. The combined cycle power plant (100) according to claim 14, further comprising an exhaust gas recirculation line configured to direct the second exhaust gas flow (120) toward the compressor inlet (168).

18. The combined cycle power plant (100) according to claim 17, further comprising a splitter configured to separate the second exhaust gas flow (120) into a first portion, a second portion, and a third portion, wherein the splitter is configured such that the first portion is between about 5% and about 10% of the second exhaust gas flow (120), the second portion is less than about 40% of the second exhaust gas flow (120), and the third portion is the remainder of the second exhaust gas flow (120), and is sized to be defined by mass.

19. The combined cycle power plant (100) according to claim 18, further comprising a carbon capture system configured to receive the third portion of the second exhaust gas flow (120).

20. The combined cycle power plant (100) according to claim 19, further comprising a second cooler (178) located upstream of the splitter.

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