SYSTEM AND METHOD FOR CONTROLLING
TEMPERATURE OF AIR AT AN INLET OF A
GAS TURBINE
BACKGROUND

[0001] Embodiments of the present disclosure relate generally to a gas turbine, and more particularly to a system and method for controlling a temperature of air at an inlet of the gas turbine.

[0002] Typically, a gas turbine is used for generating power by compressing and combusting air that is received at an inlet of the gas turbine. The generated power may be used for applications, such as power generation, marine propulsion, gas compression, and the like. If the ambient temperature of the inlet air is very high, the density of the inlet air may be reduced. As the density of the inlet air is reduced, a mass flow rate of the inlet air is also reduced, which in turn degrades the power output of the gas turbine. Thus, it is desirable to control the temperature of the inlet air to improve the power output of the gas turbine.

[0003] Various techniques have been employed to augment the power output of the gas turbine. One technique is to cool the inlet air provided to the gas turbine prior to compressing and combusting the inlet air. Cooling the inlet air increases the density of the inlet air, thereby resulting in a higher mass flow rate through the gas turbine. The higher mass flow rate through the gas turbine may in turn result in an increase in power generated by the gas turbine. However, these techniques employ vapour compression and/or vapour absorption systems that entail use of additional independent hardware components. Also, these hardware components, such as an absorber, a generator, a compressor and heat exchangers, are expensive, thereby leading to higher manufacturing costs.

BRIEF DESCRIPTION

[0004] In accordance with one embodiment described herein, a system for controlling temperature of inlet air of a gas turbine is presented. The system includes an ejector operatively coupled to a heat recovery steam generator and configured to generate an intermediate pressure refrigerant by using a high pressure refrigerant. Also, the system includes a condenser operatively coupled to the ejector and configured to extract heat from the intermediate pressure refrigerant. Further, the system includes an expanding unit operatively coupled to the condenser and configured to expand the intermediate pressure refrigerant to generate a low pressure refrigerant. In addition, the system includes a heat exchanging unit configured to receive the low pressure refrigerant from the expanding unit, the high pressure refrigerant from the heat recovery steam generator, or both, and control the temperature of the inlet air based on the received low pressure refrigerant, the received high pressure refrigerant, or both.

[0005] In accordance with a further aspect of the present disclosure, a method for controlling temperature of inlet air of a gas turbine engine is presented. The method includes generating, by an ejector, an intermediate pressure refrigerant based on a high pressure refrigerant. Also, the method includes extracting, by a condenser, heat from the intermediate pressure refrigerant. Further, the method includes expanding, by an expanding unit, the intermediate pressure refrigerant to generate a low pressure refrigerant. In addition, the method includes controlling, by a heat exchanging unit, the temperature of the inlet air using the low pressure refrigerant, the high pressure refrigerant, or both.

[0006] In accordance with another aspect of the present disclosure, a system for controlling temperature of inlet air of a gas turbine engine is presented. The system includes an ejector operatively coupled to a heat recovery vapor generator and configured to generate an intermediate pressure refrigerant by using a high pressure refrigerant. Further, the system includes a condenser operatively coupled to the ejector and configured to generate a low pressure refrigerant from the intermediate pressure refrigerant. Also, the system includes an inner chiller unit configured to receive the low pressure refrigerant from the condenser, the high pressure refrigerant from the heat recovery vapor generator, or both, and control the temperature of the inlet air based on the received low pressure refrigerant, the received high pressure refrigerant, or both.

DRAWINGS

[0007] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0008] FIG. 1 is a diagrammatical representation of a system for controlling a temperature of inlet air provided to a gas turbine, in accordance with aspects of the present disclosure;

[0009] FIG. 2 is a diagrammatical representation of another embodiment of a system for controlling a temperature of inlet air provided to a gas turbine, in accordance with aspects of the present disclosure; and

[0010] FIG. 3 is a flow chart illustrating a method for controlling a temperature of inlet air provided to the gas turbine of FIG. 1, in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

[0011] As will be described in detail hereinafter, various embodiments of exemplary systems and methods for controlling a temperature of air at an inlet of a gas turbine are presented. By employing the methods and the various embodiments of the system described hereinafter, power output of the gas turbine may be substantially improved. Moreover, waste heat of the system may be effectively used to control the temperature of the inlet air provided to the gas turbine, which in turn enhances the power output of the gas turbine.

[0012] Turning now to the drawings and referring to FIG. 1, a diagrammatical representation of a system 100 for controlling a temperature of air at an inlet of a gas turbine, in accordance with aspects of the present disclosure, is depicted. It may be noted that the term "inlet air" may be used to refer to air at an inlet of the gas turbine. The system 100 may be a combined-cycle power plant. As will be appreciated, the combined-cycle power plant may be a combination of a Brayton cyle or topping cycle and a Rankine cycle or bottoming cycle. Moreover, as depicted in FIG. 1, the system 100 includes a gas portion 104 and a steam portion 106. The gas portion 104 may operate as the Brayton cycle or the topping cycle, while the steam portion 106 may operate as the Rankine cycle or the bottoming cycle. In one embodiment, the system 100 may be a cogeneration plant or a combined heat and power (CHP) plant.

[0013] The gas portion 104 may include a gas turbine 108 that is powered by combustion of a fuel, such as natural gas or fuel oil. Particularly, the gas turbine 108 may be configured to receive inlet air 102 and compress the received inlet air 102. Further, the gas turbine 108 may be configured to generate a combustion gas by combusting the compressed inlet air. Also, the gas turbine 108 may be configured to convert thermal or heat energy of the combustion gas into mechanical energy, which may then be used for applications, such as power generation, marine propulsion, and gas compression. In the embodiment of FIG. 1, the mechanical energy of the gas turbine 108 may be used to run a power generator 110.

[0014] Subsequent to the conversion of the thermal energy of the combustion gas into the mechanical energy, the gas turbine 108 may be configured to release the combustion gas as an exhaust gas. This exhaust gas may be provided to a heat recovery steam generator (HRSG) 112. Further, the HRSG 112 may be configured to generate steam by cooling the exhaust gas that is received from the gas turbine 108. Also, the generated steam may be provided to the steam portion 106 for producing additional power. In one embodiment, the steam portion 106 may include a steam turbine 114 that is configured to generate an additional mechanical power or energy from the received steam. Further, the additional mechanical power or energy may be used for one or more applications, such as power generation, gas compression, and the like. In the embodiment of FIG. 1, the mechanical power or energy generated by the steam turbine 114 may be used to run a power generator 116.

[0015] In accordance with further aspects of the present disclosure, the steam generated by the HRSG 112 may be expanded in the steam turbine 114. Further, the steam portion 106 may include a condenser 118 that may be configured to receive the expanded steam from the steam turbine 114 and convert the expanded steam into a condensate. Further, the condensate may be channeled to the HRSG 112 and may be used again in the Rankine cycle or bottoming cycle. In one embodiment, the condensate from the condenser 118 may be passed through pumps and/or feed water heaters (not shown) before being channeled or directed to the HRSG 112.

[0016] In the combined-cycle power plant 100, the inlet air 102 and by¬products may be effectively used by the topping cycle and the bottoming cycle to generate the power. However, if the ambient temperature of the inlet air 102 is very high, the density of the inlet air 102 may be reduced. This in turn reduces the mass flow rate of the inlet air 102 and degrades the power output of the gas turbine 108. Thus, it is desirable to control the temperature of the inlet air 102 to improve the power output of the gas turbine 108.
[0017] The embodiment where the system 100 is a cogeneration plant or CHP plant, the system 100 may not include the steam turbine 114. However, the steam that is generated from the heat recovery steam generator (HRSG) 112 may be used for heating and/or process applications. However, in some instances, the steam generated by the HRSG 112 may be directly provided to the condenser 118 for cooling. This direct cooling of the steam may result in the loss of substantial amount of energy in the plant. Thus, it may be desirable to chill or cool the steam before providing the steam to the condenser 118 to enhance power output of the gas turbine 108.

[0018] In a presently contemplated configuration, the system 100 may include an ejection cycle unit 119 and a heat exchanging unit 120 configured to control the temperature of the inlet air 102 provided to the gas turbine 108. It may be noted that in FIG. 1, the ejection cycle unit 119 and the heat exchanging unit 120 are shown in the combined-cycle power plant configuration. However, the ejection cycle unit 119 and the heat exchanging unit 120 may also be implemented in other power plants configurations, such as the cogeneration plant and the CHP plant configurations.

[0019] In one embodiment, the ejection cycle unit 119 may be incorporated into the bottoming cycle, as depicted in FIG. 1. In this example, the ejection cycle unit 119 may include the HRSG 112, the condenser 118, an ejector control valve 121, an ejector 122, a flow splitter 123, an expanding unit 124, and a primary heat exchanger 128. It may be noted that in a presently contemplated configuration, the primary heat exchanger 128 may be used as a coupling element or a common element between the ejection cycle unit 119 and the heat exchanging unit 120. Furthermore, it may also be noted that the components of the ejection cycle unit 119 and the heat exchanging unit 120 may be appropriately coupled by using piping or channels, as depicted in FIG. 1. Also, the advantage of using the ejection cycle unit 119 is that the existing components such as the condenser 118 and the HRSG 112 of the combined-cycle power plant 100 may be used along with other components to control the temperature of the inlet air 102 of the gas turbine 108.

[0020] Moreover, the ejector 122 may be configured to receive a first input 130 and a second input 132. The first input 130 may be a portion of the steam that is generated by the HRSG 112. Alternatively, the first input 130 may be a portion of the steam received from the steam turbine 114. In certain examples, the first input may be received from a high pressure turbine, an intermediate pressure turbine, and/or a low pressure turbine (not shown). Further, the ejector control valve 121 may be positioned at an inlet of the ejector 122 to control an amount of the steam that is received from the HRSG 112. It may be noted that the ejector control valve 121 may be positioned at the inlet of the ejector 122 and/or an outlet of the ejector 122. In one embodiment, the ejector control valve 121 and/or the ejector 122 may receive a control signal to control a flow rate of the steam from the HRSG 112 to the ejection cycle unit 119. In one example, the control signal may be received from a control unit 138. In another embodiment, the ejection cycle unit 119 may include a plurality of ejectors (not shown) and corresponding ejector control valves for each of the ejectors (not shown) that may be positioned between the HRSG 112 and the condenser 118. Also, the individual ejectors and their respective ejector control valves may be activated or deactivated based on a power load of the system 100. In one embodiment, the plurality of ejectors may include a first set of ejectors and a second set of ejectors. The first set of ejectors may have a discrete operation, where these ejectors are activated or deactivated. In a similar manner, the second set of ejectors may have a modulating operation, where these ejectors may control or vary the flow rate of the steam from the HRSG 112. In one embodiment, the steam that is received from the HRSG 112 may be a high pressure refrigerant (HPR). The ejector 122 may be configured to receive the second input 132 from the primary heat exchanger 128. In one example, the second input 132 may be a low pressure refrigerant (LPR).

[0021] Furthermore, the ejector 122 may be configured to use the low pressure refrigerant and the high pressure refrigerant to generate an intermediate pressure refrigerant. Particularly, the ejector 122 may be configured to compress the low pressure refrigerant by using the high pressure refrigerant to generate the intermediate pressure refrigerant. Also, the ejector 122 may be configured to direct the intermediate pressure refrigerant towards the condenser 118, where the condenser 118 may be configured to extract heat from the intermediate pressure refrigerant. The intermediate pressure refrigerant may be directed from the condenser 118 towards the expanding unit 124 via the flow splitter 123. In one embodiment, the flow splitter 123 may be used to control a flow rate of the intermediate pressure refrigerant based on an amount of steam provided by the HRSG 112 and/or the steam turbine 114. In one example, the flow splitter 123 may control the flow rate of the intermediate pressure refrigerant by splitting or directing a portion of the intermediate pressure refrigerant to the HRSG 112. Further, in the expanding unit 124, the received intermediate pressure refrigerant is expanded to produce a low pressure refrigerant. In one embodiment, the expanding unit 124 may include a Joule-Thomson (JT) expansion device that is used to reduce the pressure of the intermediate pressure refrigerant by contraction. In addition, the low pressure refrigerant may be channeled through the primary heat exchanger 128 and directed back to the ejector 122 to sustain the cycle in the ejection cycle unit 119.

[0022] Also, in addition to the primary heat exchanger 128, the heat exchanging unit 120 may include a secondary heat exchanger 134 and a pump 136. The secondary heat exchanger 134 may be coupled to an inlet of the gas turbine 108 that is configured to receive the inlet air 102 and channel the inlet air to the gas turbine 108. Further, a fluid may be circulated between the primary heat exchanger 128 and the secondary heat exchanger 134 via the pump 136. In one example, the circulating fluid may include a water-glycol mix. The circulating fluid may be configured to absorb the heat from the inlet air 102 while passing through the secondary heat exchanger 134. Moreover, the circulated fluid may transfer the absorbed heat to the low pressure refrigerant at the primary heat exchanger 128. This cycle may be sustained to maintain the temperature of the inlet air 102 at a value below a threshold temperature. In one example, the threshold temperature may be about 15 degree Celsius. Thus, by using the ejection cycle unit 119 and the heat exchanging unit 120, the temperature of the inlet air 102 may be controlled.

[0023] Further, under certain conditions, the gas turbine 108 may operate at a lower power load. In one example, the lower power load may be a power load of the gas turbine 108 that is below a threshold power load. Also, it may be noted that the power load is referred to as a desired amount of power that the gas turbine 108 has to generate to support one or more applications. Under these operating conditions, it may be desirable to increase the temperature of the inlet air 102 so as to increase the efficiency of the gas turbine 108. To that end, a high pressure refrigerant may be conveyed through a separate channel from the HRSG 112 to the primary heat exchanger 128 via a valve 154. In one embodiment, the high pressure refrigerant may include a hot fluid. This high pressure refrigerant may transfer the heat to the fluid that is circulated between the primary heat exchanger 128 and the secondary heat exchanger 134. The circulating fluid may in turn transfer the absorbed heat to the inlet air 102 to increase the temperature of the inlet air 102. Moreover, the high pressure refrigerant may be directed from the primary heat exchanger 128 to the condenser 118, where the high pressure refrigerant may be cooled and directed back to the HRSG 112. This cycle may be sustained to maintain the temperature of the inlet air 102 at a value above the threshold temperature, which in turn aids in increasing the efficiency of the gas turbine 108.

[0024] In addition, the system 100 may be configured to selectively allow passage of the high pressure refrigerant and/or the low pressure refrigerant through the primary heat exchanger 128 depending upon the temperature of the inlet air 102 and the power load of the gas turbine 108. Accordingly, the system 100 may include the control unit 138 configured to selectively allow the high pressure refrigerant or the low pressure refrigerant to pass through the primary heat exchanger 128.

[0025] In addition, the system 100 may also include a first valve 140 and a second valve 142. The first valve 140 may be coupled to an inlet of the primary heat exchanger 128 and configured to allow one of the high pressure refrigerant and the low pressure refrigerant to flow through the primary heat exchanger 128. Further, the second valve 142 may be coupled to an outlet of the primary heat exchanger 128 and configured to direct the high pressure refrigerant to the condenser 118 and the low pressure refrigerant to the ejector 122.

[0026] Moreover, the control unit 138 may be configured to determine the temperature of the inlet air 102. In one embodiment, the control unit 138 may use a first temperature sensor 144 and a second temperature sensor 150 to determine the temperature of the inlet air 102. In one example, the control unit 138 may use these temperature sensors 144, 150 to determine the temperature of the inlet air 102 before providing the inlet air 102 to the gas turbine 108. In particular, the control unit 138 may be configured to determine whether the temperature of the inlet air 102 is above the threshold temperature and the power load of the gas turbine 108 is above the threshold power load. If the temperature of the inlet air 102 is above the threshold temperature and the power load of the gas turbine 108 is above the threshold power load, the control unit 138 may be configured to communicate a first control signal to the first valve 140 and the second valve 142 to allow passage of the low pressure refrigerant through the primary heat exchanger 128 and towards the ejector 122. Passage of the low pressure refrigerant through the primary heat exchanger 128 aids in cooling the fluid in the heat exchanging unit 120, which in turn reduces the temperature of the inlet air 102. This reduction in temperature of the inlet air 102 may aid in increasing the power output of the gas turbine 108. Further, the increase in the power output of the gas turbine 108 may in turn support the power load of the gas turbine 108 that is above the threshold power load. In one embodiment, the control unit 138 may include a user interface 152 that is configured to receive one or more input signals from an operator and/or an external device. The input signals may indicate the power load of the gas turbine 108. Also, the input signals may indicate a value of the threshold power load and/or a value of the threshold temperature.

[0027] In a similar manner, the control unit 138 may be configured to determine whether the temperature of the inlet air 102 is below the threshold temperature and the power load of the gas turbine 108 is below the threshold power load. If the temperature of the inlet air 102 is below the threshold temperature and the power load of the gas turbine 108 is below the threshold power load, the control unit 138 may be configured to communicate a second control signal to the first valve 140 and the second valve 142 to allow passage of the high pressure refrigerant through the primary heat exchanger 128 and towards the condenser 118. Passage of the high pressure refrigerant through the primary heat exchanger 128 facilitates increasing the temperature of the fluid in the heat exchanging unit 120, which in turn increases the temperature of the inlet air 102. Thus, the temperature of the inlet air 102 may be controlled by selectively allowing passage of the high pressure refrigerant and/or the low pressure refrigerant to pass through the primary heat exchanger 128. In one embodiment, the threshold temperature and the threshold power load that is used by the control unit 138 to reduce the temperature of the inlet air 102 may be different from the threshold temperature and the threshold power load that is used by the control unit 138 to increase the temperature of the inlet air 102.

[0028] In one embodiment, the control unit 138 may be configured to communicate a third control signal to the pump 136 to deactivate the pump 136 and stop circulating the fluid between the primary heat exchanger 128 and the secondary heat exchanger 134. Particularly, when the temperature of the inlet air 102 is below the threshold temperature and the gas turbine 108 is running at a full load, the need to control the temperature of the inlet air 102 may be obviated. Accordingly, the pump 136 may be deactivated to save electrical power and to increase the efficiency of the system 100.

[0029] Further, it may be noted that the ejection cycle unit 119 may employ a variety of configurations to allow passage of the high pressure refrigerant and/or the low pressure refrigerant through the primary heat exchanger 128, and is not limited to the configuration shown in FIG. 1. Also, the other configurations may entail use of additional components, such as an auxiliary pump, a vapour-liquid separator, and an additional ejector, along with the existing components of the ejection cycle unit 119.

[0030] Referring to FIG. 2, a diagrammatical representation of another system 200 for controlling a temperature of an inlet air provided to a gas turbine, in accordance with aspects of the present disclosure, is depicted. The system 200 may be a simple-cycle power plant that includes a gas turbine 202 for generating power. The gas turbine 202 may be configured to receive inlet air 204. Also, the gas turbine 202 may be configured to compress and combust the inlet air 204 to generate a combustion gas. Further, the combustion gas may be used to generate power by converting the thermal energy of the combustion gas into mechanical energy. In one embodiment, the mechanical energy of the gas turbine 202 may be used to run a power generator 220. After converting the thermal energy of the combustion gas into mechanical energy, the combustion gas may exit the gas turbine 202 as an exhaust gas. The exhaust gas may be provided to a gas turbine stack 206. The exhaust gas may be delivered to the surrounding environment from the gas turbine stack 206.

[0031] In the exemplary embodiment of FIG. 2, the system 200 is shown as including an ejection cycle unit 208 configured to control the temperature of the inlet air 204. The ejection cycle unit 208 may be configured to utilize waste heat of the exhaust gas to control the temperature of the inlet air 204. Also, the ejection cycle unit 208 may be used in other gas turbine plants, such as aero-derivative gas turbines.

[0032] In a presently contemplated configuration, the ejection cycle unit 208 may include a heat recovery vapour generator (HRVG) 210, an inner chiller unit 212, a condenser 214, an ejector control valve 215, an ejector 216, a flow splitter 217, and a pump 218. Also, a refrigerant may be circulated in the ejection cycle unit 208 to control the temperature of the inlet air 204. The HRVG 210 may be coupled to an outlet of the gas turbine 202, while the inner chiller unit 212 may be coupled to an inlet of the gas turbine 202. Further, the refrigerant may be circulated between the HRVG 210 and the inner chiller unit 212 via use of the ejector 216, the condenser 214, and the pump 218. As depicted in FIG. 2, the refrigerant may be heated by the exhaust gas in the HRVG 210 and a hot high- pressure refrigerant vapour may be provided as a first input to the ejector 216 via a first control valve 224. In one embodiment, the ejector control valve 215 may be positioned at an inlet of the ejector 216 to control a flow rate of the high pressure refrigerant vapor received from the HRVG 210. In one example, the ejector control valve 215 and/or the ejector 216 may receive a control signal to control the flow rate of the high pressure refrigerant vapor received from the HRVG 210. In another embodiment, the ejection cycle unit 208 may include a plurality of ejectors and a corresponding ejector control valve (not shown) that may be positioned between the HRVG 210 and the condenser 214. Also, the plurality of ejectors may include a first set of ejectors and a second set of ejectors. The first set of ejectors may have a discrete operation, where these ejectors are activated or deactivated. In a similar manner, the second set of ejectors may have a modulating operation, where these ejectors may control or vary the flow rate of the high pressure refrigerant vapor received from the HRVG 210.

[0033] Also, the ejector 216 may receive a low pressure refrigerant vapour as a second input from the inner chiller unit 212. Further, the ejector 216 may use the high-pressure refrigerant vapor to compress the low pressure refrigerant vapour and generate an intermediate pressure refrigerant vapour. The intermediate pressure refrigerant vapor may be condensed by using the condenser 214 to produce a low pressure refrigerant liquid. Further, the low pressure refrigerant liquid may be split or divided into two streams by using the flow splitter 217. A first stream of the low pressure refrigerant liquid may be throttled in a valve 222 via a second control valve 226 and provided to the inner chiller unit 212 to cool the inlet air 204. The first stream of the low pressure refrigerant liquid may be configured to absorb heat from the inlet air 204 and reduce the temperature of the inlet air 204. Further, the first stream of the low pressure refrigerant vapour may be directed back to the ejector 216 or the condenser 214 via a third valve 219 to sustain this cycle. Similarly, a second stream of the low pressure refrigerant liquid from the condenser 214 may be processed via use of the pump 218 to increase the pressure of the second stream. Further, this high pressure refrigerant liquid may be directed back to the HRVG 210 and used to absorb the heat from the exhaust gas. This cycle may be sustained to maintain the temperature of the inlet air 204 at a value below a threshold temperature. As previously noted, the threshold temperature may be about 15 degrees Celsius, in one example.

[0034] In addition, if a power load of the gas turbine 202 is below a threshold power load, it may be desirable to increase the temperature of the inlet air 204 so as to improve the efficiency of the system 200. It may be noted that the power load is referred to as a desired amount of power that the gas turbine 108 has to generate to support one or more applications. To improve the system efficiency, the system 200 may include a control unit 228. The control unit along with the first control valve 224 and the second control valve 226 may be used to control the temperature of the inlet air 204. More specifically, the control unit 228 may use a first temperature sensor 230 and a second temperature sensor 232 to determine the temperature of the inlet air 204. In one example, the control unit 228 may use these temperature sensors 230, 232 to determine the temperature of the inlet air 204 before providing the inlet air 204 to the gas turbine 202.

[0035] In particular, the control unit 228 may be configured to determine whether the temperature of the inlet air 204 is below the threshold temperature and the power load of the gas turbine 202 is below the threshold power load. If the temperature of the inlet air 204 is below the threshold temperature and the power load of the gas turbine 202 is below the threshold power load, the control unit 228 may be configured to communicate a first control signal to the first valve 224, the second valve 226, and the third valve 219 to allow passage of the hot high-pressure refrigerant vapour from the HRVG 210 to the inner chiller unit 212 via a valve 238. Further, this high-pressure refrigerant vapor may be directed from the inner chiller unit 212 to the condenser 214 via the third valve 219. Passage of the hot high-pressure refrigerant vapour through the inner chiller unit 212 aids in heating the inlet air 204, which in turn increases the temperature of the inlet air 204. In one embodiment, the control unit 228 may include a user interface 236 that is configured to receive one or more input signals from an operator and/or an external device. The input signals may indicate the power load of the gas turbine 202. Also, the input signals may indicate a value of the threshold power load and/or a value of the threshold temperature.

[0036] In a similar manner, the control unit 228 may be configured to determine whether the temperature of the inlet air 204 is above the threshold temperature and the power load of the gas turbine 202 is above the threshold power load. If the temperature of the inlet air 204 is above the threshold temperature and the power load of the gas turbine 202 is above the threshold power load, the control unit 228 may be configured to communicate a second control signal to the first valve 224, the second valve 226, and the third valve 219 to allow passage of the hot high-pressure refrigerant vapour from the HRVG 210 to the ejector 216, where the high-pressure refrigerant vapour may be used to compress the low pressure refrigerant vapour and generate an intermediate pressure refrigerant vapour. The intermediate pressure refrigerant vapour may be condensed by using the condenser 214 to produce a low pressure refrigerant liquid. Further, the low pressure refrigerant liquid may be split or divided into two streams. A first stream of the low pressure refrigerant liquid may be throttled in the valve 222 via the second control valve 226 and provided to the inner chiller unit 212 to cool the inlet air 204, which in turn decreases the temperature of the inlet air 204. Further, the low pressure refrigerant is directed from the inner chiller unit 212 to the ejector 216 via the third valve 219. In one embodiment, the threshold temperature and the threshold power load that is used by the control unit 228 to reduce the temperature of the inlet air 204 may be different from the threshold temperature and the threshold power load that is used by the control unit 228 to increase the temperature of the inlet air 204.

[0037] Thus, the temperature of the inlet air 204 may be controlled by selectively allowing passage of the high pressure refrigerant and/or the low pressure refrigerant to pass through the inner chiller unit 212. Hence, by employing the ejection cycle unit 208 in the simple-cycle power plant 200, the temperature of the inlet air 204 may be effectively controlled. Also, the power output and/or efficiency of the gas turbine 202 may be substantially improved. It may be noted that the ejection cycle unit 208 may have different configurations with one or more additional components, and is not limited to the configuration shown in FIG. 2.

[0038] Turning to FIG. 3, a flow chart 300 illustrating a method for controlling a temperature of inlet air provided to a gas turbine, in accordance with aspects of the present disclosure, is depicted. For ease of understanding, the method 300 is described with reference to the components of FIG. 1. The method begins at step 302, wherein an intermediate pressure refrigerant is generated using a high pressure refrigerant. In one embodiment, the ejector 122 may be used to generate the intermediate pressure refrigerant. In addition, the ejector 122 may also be configured to receive a low pressure refrigerant from the primary heat exchanger 128. The ejector 122 may be configured to use the high pressure refrigerant to compress the low pressure refrigerant to produce the intermediate pressure refrigerant.

[0039] Subsequently, at step 304, heat from the intermediate pressure refrigerant may be extracted. In one embodiment, the condenser 118 may be used to extract the heat from the intermediate pressure refrigerant. As previously noted, the intermediate pressure refrigerant may include heat that is transferred from the high pressure refrigerant received from the HRSG 112. The condenser 118 may be used to dissipate this heat from the intermediate pressure refrigerant.

[0040] In addition, at step 306, the intermediate pressure refrigerant may be expanded to generate a low pressure refrigerant. In one example, the expanding unit 124 may be used to generate the low pressure refrigerant. Particularly, the expanding unit 124 may include a Joule-Thomson (JT) that may be configured to expand the intermediate pressure refrigerant to produce the low pressure refrigerant.

[0041] Furthermore, as indicated by step 308, the temperature of the inlet air 102 may be controlled using one of the low pressure refrigerant and the high pressure refrigerant. In one embodiment, the heat exchanging unit 120 may be used to control the temperature of the inlet air 102. Particularly, the control unit 138 may be configured to determine a temperature of the inlet air 102 and a power load of the gas turbine 108. If the temperature of the inlet air 102 is above a threshold temperature and the gas turbine 108 is operating above a threshold power load, the control unit 138 may be configured to communicate a first control signal to the first valve 140 and the second valve 142. In response to the first control signal, the first valve 140 and the second valve 142 may be configured to direct the low pressure refrigerant through the primary heat exchanger 128 and towards the ejector 122. While passing through the primary heat exchanger 128, the low pressure refrigerant may absorb heat from the fluid that is circulating in the heat exchanging unit 120. Further, the cooled circulating fluid may be channeled through the secondary heat exchanger 134 to absorb the heat from the inlet air 102 and reduce the temperature of the inlet air 102.

[0042] In a similar manner, if the temperature of the inlet air 102 is below the threshold temperature and the gas turbine 108 is operating below the threshold power load, the control unit 138 may be configured to transmit a second control signal to the first valve 140 and the second valve 142. In response to the second control signal, the first valve 140 and the second valve 142 may be configured to allow the high pressure refrigerant to pass through the primary heat exchanger 128. Furthermore, the high pressure refrigerant may be directed towards the condenser 118. While passing through the primary heat exchanger 128, the high pressure refrigerant may transfer heat to the fluid that is circulated in the heat exchanging unit 120. This fluid may in turn transfer the heat to the inlet air 102 thereby increasing the temperature of the inlet air 102. Thus, by employing the ejection cycle unit 119 and the heat exchanging unit 120, the temperature of the inlet air 102 may be controlled and the efficiency of the gas turbine 108 may be substantially improved.

[0043] The various embodiments of the system and method aid in controlling the temperature of the inlet air. Also, as the system employs the ejection cycle unit and the heat exchanging unit in the power plant, the temperature of the inlet air may be controlled based on the power output of the gas turbine. This in turn aids in improving the efficiency and/or the power output of the gas turbine. Also, the ejection cycle unit may be used to cool the inlet air at a much lower cost than traditional refrigeration systems.
[0044] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

CLAIMS:

1. A system for controlling a temperature of inlet air provided to a gas turbine, the system comprising:
an ejector operatively coupled to a heat recovery steam generator and configured to generate an intermediate pressure refrigerant by using a high pressure refrigerant;
a condenser operatively coupled to the ejector and configured to extract heat from the intermediate pressure refrigerant;
an expanding unit operatively coupled to the condenser and configured to expand the intermediate pressure refrigerant to generate a low pressure refrigerant;
a heat exchanging unit configured to:
receive the low pressure refrigerant from the expanding unit, the high pressure refrigerant from the heat recovery steam generator, or both; and
control the temperature of the inlet air based on the received low pressure refrigerant, the received high pressure refrigerant, or both.

2. The system of claim 1, wherein the ejector is operatively coupled to the heat exchanging unit and configured to: receive the low pressure refrigerant from the heat exchanging unit; and compress the received low pressure refrigerant to generate the intermediate pressure refrigerant.

3. The system of claim 2, wherein the ejector is configured to compress the low pressure refrigerant by employing the high pressure refrigerant received from the heat recovery steam generator.

4. The system of claim 1, wherein the heat exchanging unit comprises:
a primary heat exchanger configured to receive the low pressure refrigerant, the high pressure refrigerant, or both;
a secondary heat exchanger operatively coupled to an inlet of the gas turbine and configured to receive the inlet air; and
a pumping unit operatively coupled to the primary heat exchanger and the secondary heat exchanger and configured to circulate a circulating fluid between the primary heat exchanger and the secondary heat exchanger.

5. The system of claim 4, wherein the circulating fluid is configured to absorb heat from the inlet air while passing through the secondary heat exchanger, and wherein the circulating fluid is configured to transfer the absorbed heat to the low pressure refrigerant while passing through the primary heat exchanger.

6. The system of claim 4, wherein the circulating fluid is configured to absorb heat from the high pressure refrigerant while passing through the primary heat exchanger, and wherein the circulating fluid is configured to release the absorbed heat to the inlet air while passing through the secondary heat exchanger.

7. The system of claim 4, further comprising a control unit configured to control passage of the low pressure refrigerant, the high pressure refrigerant, or both through the primary heat exchanger.

8. The system of claim 7, further comprising:
a first valve coupled to an inlet of the primary heat exchanger; and a second valve coupled to an outlet of the primary heat exchanger.

9. The system of claim 8, wherein the control unit is configured to communicate a first control signal to the first valve and the second valve to allow the low pressure refrigerant to pass through the primary heat exchanger and direct the low pressure refrigerant towards the ejector.

10. The system of claim 9, wherein the control unit is configured to communicate the first control signal to the first valve and the second valve when the temperature of the inlet air is above a threshold temperature and a power load of the gas turbine is above a threshold power load.

11. The system of claim 8, wherein the control unit is configured to communicate a second control signal to the first valve and the second valve to allow the high pressure refrigerant to pass through the primary heat exchanger and direct the high pressure refrigerant towards the condenser.

12. The system of claim 11, wherein the control unit is configured to communicate the second control signal to the first valve and the second valve when the temperature of the inlet air is below a threshold temperature and the power load of the gas turbine is below a threshold power load.

13. A method for controlling temperature of inlet air of a gas turbine engine, the method comprising:
generating, by an ejector, an intermediate pressure refrigerant based on a high pressure refrigerant;
extracting, by a condenser, heat from the intermediate pressure refrigerant;
expanding, by an expanding unit, the intermediate pressure refrigerant to generate a low pressure refrigerant; and
controlling, by a heat exchanging unit, the temperature of the inlet air using the low pressure refrigerant, the high pressure refrigerant, or both.

14. The method of claim 13, wherein generating the intermediate
pressure refrigerant comprises:
receiving a low pressure refrigerant from the heat exchanging unit; and
compressing the received low pressure refrigerant to generate the intermediate pressure refrigerant.

15. The method of claim 14, wherein compressing the received low pressure refrigerant comprises employing the high pressure refrigerant received from a heat recovery steam generator to compress the received low pressure refrigerant.

16. The method of claim 13, wherein controlling the temperature of the inlet air comprises guiding the low pressure refrigerant, the high pressure refrigerant, or both through a primary heat exchanger.

17. The method of claim 16, further comprising communicating a first control signal to a first valve and a second valve to allow the low pressure refrigerant to pass through the primary heat exchanger and towards the ejector, wherein the first control signal is communicated to the first valve and the second valve when the temperature of the inlet air is above a threshold temperature and a power load of the gas turbine is above a threshold power load.

18. The method of claim 16, further comprising communicating a second control signal to a first valve and a second valve to allow the high pressure refrigerant to pass through the primary heat exchanger and towards the condenser, wherein the second control signal is communicated to the first valve and the second valve when the temperature of the inlet air is below a threshold temperature and a power load of the gas turbine is below a threshold power load.

19. A system for controlling a temperature of inlet air provided to a gas turbine, the system comprising:
an ejector operatively coupled to a heat recovery vapor generator and configured to generate an intermediate pressure refrigerant by using a high pressure refrigerant;
a condenser operatively coupled to the ejector and configured to generate a low pressure refrigerant from the intermediate pressure refrigerant;
an inner chiller unit configured to:
receive the low pressure refrigerant from the condenser, the high pressure refrigerant from the heat recovery vapor generator, or both; and
control the temperature of the inlet air based on the received low pressure refrigerant, the received high pressure refrigerant, or both.

20. The system of claim 19, further comprising a control unit configured to control passage of the low pressure refrigerant, the high pressure refrigerant, or both through the inner chiller unit based on the temperature of the inlet air.