System and method for controlling temperature in an air intake

Abstract

The system includes a temperature control system (11) configured to be coupled to an air intake section (14) of a gas turbine system (10). The temperature control system (11) includes a variable heating system (12) having one or more heaters (28) configured to heat the airflow in the air intake section (14) when the airflow is cooled by an evaporative cooling system (13, 26). The temperature control system (11) is configured to control the variable heating system (12) to change the amount of heat supplied by one or more heaters (28) based on at least one temperature measurement for a temperature threshold.

Description

Background Technology

[0001] The gist of the present specification is to a gas turbine, and more specifically, to a system and method for changing the temperature of air received by an air intake of a gas turbine.

[0002] A gas turbine, or gas turbine engine, may include an air intake section, a compressor section, a combustion section, a turbine section, and an exhaust section. During operation, the air intake section receives intake air from the surrounding environment, and the compressor section compresses the intake air. The compressed air flows into the combustion section, which uses the compressed air to generate hot combustion gases for the combustion of one or more fuels. The hot combustion gases drive the rotation of the turbine section, which in turn drives the compressor section and one or more loads, such as a generator.

[0003] The temperature of the air received from the intake section by the compressor section affects the compression of the air and the power output by the gas turbine. For example, a lower intake air temperature allows the compressor section to supply a greater mass flow of compressed air to the combustion section at a lower temperature, thereby increasing the power output by the gas turbine. However, if the gas turbine produces too much power as a result of the intake air temperature being too low, regulation (e.g., partial closure of the inlet guide vane) may be performed to reduce the power output of the gas turbine. A higher intake air temperature causes the compressor section to supply a smaller mass flow of compressed air to the combustion section at a higher temperature, thereby reducing the power output by the gas turbine.

[0004] There is a need to control the temperature of the air intake to control the mass flow of compressed air and the power output of the gas turbine.

[0005] Specific embodiments corresponding to the claims and categories of the original application are summarized below. These embodiments are not intended to limit the scope of the art, but rather are intended to provide a brief overview of possible forms of the art. In practice, the system and method may include various forms that may be similar or different from the embodiments presented below.

[0006] In a given embodiment, the system includes a temperature control system configured to be coupled to an air intake section of a gas turbine system. The temperature control system includes a variable heating system having one or more heaters configured to heat the airflow in the air intake section when the airflow is cooled by an evaporative cooling system. The temperature control system is configured to control the variable heating system to vary the amount of heat supplied by one or more heaters based on at least one temperature measurement relative to a temperature threshold.

[0007] In a given embodiment, the method comprises the step of controlling a temperature control system to control the temperature of an airflow in an air intake section of a gas turbine system. The method comprises the step of controlling an evaporative cooling system to cool the airflow in the air intake section. The method further comprises the step of controlling a variable heating system having one or more heaters to heat the airflow in the air intake section, wherein the step of controlling the variable heating system comprises the step of changing the amount of heat supplied by one or more heaters based on at least one temperature measurement relative to a temperature threshold.

[0008] In a given embodiment, the system includes a temperature control system configured to be coupled to an air intake section of a gas turbine system. The temperature control system includes an evaporative cooling system configured to cool the airflow in the air intake section. The temperature control system also includes a variable heating system having one or more heaters configured to heat the airflow in the air intake section. Additionally, the temperature control system includes a controller configured to control the variable heating system to vary the amount of heat supplied by one or more heaters based on at least one temperature measurement relative to a temperature threshold. Brief explanation of the drawing

[0009] These and other features, aspects, and advantages of the present invention will be better understood when reading the following detailed description with reference to the accompanying drawings, in which similar characters indicate similar parts throughout the drawings. FIG. 1 is a block diagram of an embodiment of a gas turbine system having a temperature control system equipped with an evaporative cooling system and a variable heating system. Figure 2 is a diagram of an embodiment of an evaporative cooling system of the gas turbine system of Figure 1. Figure 3 is a diagram of one embodiment of the variable heating system of the gas turbine of Figure 1. FIG. 4 is a flowchart of one embodiment of a process for controlling the temperature in the intake section of a gas turbine system using the temperature control system of FIG. 1 to 3. Specific details for implementing the invention

[0010] One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, not all features of actual embodiments may be described in the specification. It should be understood that in the development of any such actual embodiment, as in any engineering or design project, numerous embodiment-specific decisions must be made to achieve specific goals of the developers, such as adhering to system-related and business-related constraints, and that these may vary from embodiment to embodiment. Furthermore, it should be understood that while such development efforts may be complex and time-consuming, they will nevertheless be routine tasks of design, manufacturing, and production for those skilled in the art who have an interest in this disclosure.

[0011] When introducing elements of various examples of the present invention, the articles “a,” “an,” “the,” and “said” are intended to imply that one or more of the elements are present. The terms “comprising,” “including,” and “having” are intended to be inclusive and imply that there may be additional elements other than those listed. Additionally, it should be understood that references to “one example” or “an example” of the present invention are not intended to be interpreted as excluding the existence of additional examples that also include the mentioned features.

[0012] In this context, the terms “about” or “approximately” are intended to imply that the indicated value is not accurate and that the actual value may differ from the indicated value in a manner that does not substantially alter the relevant operation. For example, the terms “about” or “approximately” as used herein are intended to indicate a suitable value within a specific tolerance (e.g., ±10%, ±5%, ±1%, ±0.5%) as will be understood by those skilled in the art.

[0013] As discussed in detail below, the disclosed embodiment includes a temperature control system in an air intake section upstream of the compressor section of a gas turbine, wherein the temperature control system includes a cooling system (e.g., an evaporative cooling system) and a variable heating system (e.g., one or more heaters). The variable heating system is configured to regulate the temperature while enabling continuous operation of the evaporative cooling system. The evaporative cooling system helps to increase the efficiency of the compressor section by lowering the temperature of the intake air upstream of the compressor section. In particular, the evaporative cooling system is configured to lower the temperature of the intake air so that the compressor section can supply a greater mass flow of compressed air to the combustion section at a lower temperature, thereby increasing the power output by the gas turbine.

[0014] If the temperature of the intake air drops below one or more lower temperature thresholds, the temperature control system may enable the variable heating system to optionally offset the cooling effect by raising the temperature of the intake air to a temperature above one or more temperature thresholds. The lower temperature thresholds may include an anti-icing temperature threshold. The anti-icing temperature threshold may be a lower temperature limit to help suppress ice formation, e.g., a temperature above the freezing temperature. In some embodiments, the temperature threshold may be selected to achieve a power output by the gas turbine at a predetermined level without the need to at least partially close the compressor's inlet guide vanes (IGV). In some embodiments, the temperature threshold may be selected to reduce the emission level below the threshold.

[0015] An evaporative cooling system may be configured to cool intake air by mixing intake air with an evaporated liquid (e.g., water vapor) from an evaporative cooling medium containing an absorbed cooling liquid (e.g., water). However, the operating state of the evaporative cooling system may be completely wet when in use or completely dry when not in use. That is, in some embodiments, the evaporative cooling system may not have a "part-load" operating point. Unless otherwise disclosed, the evaporative cooling system may supercool intake air.

[0016] There are many cases where gas turbines are output-limited, and any additional power exceeding these output limits cannot be allowed to the power grid. In such cases, the gas turbine operator will typically need to stop the evaporative cooling system and / or at least partially close the inlet guide vanes (IGVs) of the compressor section. Stopping the evaporative cooler can cause the unit to produce less power output than transmitted, and therefore, this measure is not always a viable option. While closing the IGVs allows the gas turbine operator to modulate the unit output to avoid exceeding output limits, doing so negatively and significantly affects the efficiency of the gas turbine and results in increased fuel consumption. The disclosed embodiments are intended to address these drawbacks of conventional evaporative cooling systems.

[0017] Accordingly, the disclosed embodiment complements an evaporative cooling system with a variable heating system that enables granular control of the temperature of the air received by the air intake section to achieve a desired power output. Generally, the variable heating system includes a variable heating controller and one or more variable heaters (e.g., electric heaters, heat exchangers, etc.) that may be positioned within the air intake section, for example, in proximity to the evaporative cooling system (e.g., upstream, downstream, or largely overlapping axial positions relative to the evaporative cooling system). In some cases, the variable heating system may be refitted within an existing air intake section containing the evaporative cooling system.

[0018] In general operation, the variable heating controller is configured to generate a control signal based on feedback indicating conditions of the gas turbine and / or ambient air to cause one or more heaters to heat the received air. In some embodiments, the variable heating controller may receive feedback from one or more sensors (e.g., temperature, humidity, pressure, etc.) indicating conditions (e.g., temperature, humidity, pressure, etc.) of the ambient air or air within various components of the gas turbine (e.g., air in the compressor before compression, air flowing into the combustion section after compression, temperature of the exhaust gas, etc., as further discussed herein). In some embodiments, the feedback may include operating conditions of the gas turbine, such as the current power output by the gas turbine, the position of the inlet guide vanes (IGV), etc. Furthermore, the controller may use the feedback to modify the operation of one or more heaters when the operating parameters of the gas turbine deviate from a threshold, such as the desired power output of the gas turbine. In this way, the variable heating system can at least partially automate the control of the temperature of the air received by the gas turbine to achieve the desired power output and efficiency.

[0019] FIG. 1 is a diagram of one embodiment of a gas turbine system (10) having a temperature control system (11) configured to control the temperature of the flow (e.g., air flow) of intake air (9) into the gas turbine system (10). In particular, the temperature control system (11) includes a variable heating system (12) and a cooling system (13) (e.g., evaporative cooling system (26)) which is positioned along an air intake section (14) (e.g., an air intake duct) and configured to provide a desired temperature of the intake air (9). In a given embodiment, the variable heating system (12) is configured to provide a variable amount of heat to the intake air while the cooling system (13) (e.g., evaporative cooling system (26)) is operating continuously in a full operating mode. In other words, the evaporative cooling system (26) may be operating in a simply "on" configuration while the variable heating system (12) is used to control the temperature of the intake air based on one or more temperature thresholds.

[0020] As discussed in more detail below, the variable heating system (12) may be integrated with and / or separated from the cooling system (13, 26). For example, the variable heating system (12) may be at least partially or completely contained within the cooling system (13, 26) (e.g., within a common enclosure (15)), or upstream of the cooling system (13, 26) and / or downstream of the cooling system (13, 26). Furthermore, the variable heating system (12) and / or the cooling system (13, 26) may be at least partially or completely contained within the air intake section (14) (e.g., an air intake duct).

[0021] In the illustrated embodiment, the gas turbine system (10) comprises an air intake section (14) having a temperature control system (11), a compressor section (16) fluidly communicating with the air intake section (14), a combustion section (18), and a turbine (20). The compressor section (16) may include a plurality of inlet guide vanes (IGV) (22) arranged downstream of the air intake section (14). In at least some cases, for example in a land-based gas turbine, the turbine (20) may drive a generator (24). The air intake section (14) includes a cooling system (13) (e.g., an evaporative cooling system (26)) for cooling the air received by the air intake section (14), as discussed in more detail with respect to FIG. 2.

[0022] The air intake section (14) also includes one or more heaters (28) of the variable heating system (12). One or more heaters (28) may be arranged in various locations within the air intake section (14), for example, in series and / or parallel with respect to the flow direction through the air intake section (14). For example, one or more heaters (28) may be arranged in a first axial location (30) upstream of the evaporative cooling system (26), a second axial location (32) that at least partially overlaps with the axial location of the evaporative cooling system (26), and / or a third axial location (34) downstream of the evaporative cooling system (26). As discussed in more detail with respect to FIG. 3, the approximate axial position of one or more heaters (28) for the evaporative cooling system (26) can provide certain advantages, such as reducing the possibility of freezing of the IGV (22) and reducing the amount of cooling fluid from the evaporative cooling system (26) consumed by the air received by the air intake section (14).

[0023] When in operation, the air intake section (14) receives air (e.g., intake air (9)) from the surrounding environment. While the air flows through the air intake section (14), an evaporative cooling system (26) can cool the air and / or one or more heaters (28) can heat the air. Subsequently, the cooled and / or heated air flows through a plurality of IGVs (22) positioned at the inlet of the compressor section (16). Generally, the positioning of the plurality of IGVs (22) can control the amount of air flowing into the compressor section (16) and, accordingly, control the power output by the gas turbine (10). The compressor section (16) includes one or more compressor stages (e.g., 1 to 30 compressor stages) that progressively compress the air upstream of the combustion section (18).

[0024] The combustion section (18) burns fuel together with compressed air from the compressor section (16) to produce high-temperature combustion gas (or exhaust gas). The combustion section (18) may include one or more combustors, such as an annular combustor or a plurality of combustor cans, arranged circumferentially around the axis of the gas turbine (10). Each combustor of the combustion section (18) includes one or more fuel nozzles (19) for injecting fuel into a combustion chamber for combustion. The high-temperature combustion gas (or exhaust gas) flows through the turbine section (20) and drives its rotation. For example, the high-temperature combustion gas can drive the rotation of one or more turbine stages (e.g., one to five turbine stages) of the turbine section (20). The rotating turbine section (20) then drives the rotation of one or more loads, such as the compressor section (16) and the generator (24), through a common shaft.

[0025] In a given embodiment, the operation of the temperature control system (11) (e.g., variable heating system (12) and cooling system (13, 26)) and / or the gas turbine system (10) may be at least partially controlled by a controller (36) having a processor (38) capable of executing instructions stored in memory (40) and / or a storage medium (42), or based on input provided by a user through an input / output (I / O) device (44). The memory (40) and / or the storage medium (42) may be, for example, a read-only memory (ROM), random access memory (RAM), flash memory, an optical storage medium, or a hard disk drive. For example, during operation, the processor (38) may transmit a suitable control signal to actuate the valve of the fuel supply system (21) to regulate the fuel supply to the fuel nozzle (19) of the combustion section (18). As an additional example, the processor (38) may transmit a suitable control signal to control the operation of a temperature control system (11), such as a cooling system (13, 26) and a variable heating system (12) (e.g., one or more heaters (28)) to control the temperature of the intake air (9). As another example, the processor (38) may transmit a suitable control signal to control the operation of an IGV (22), such as opening or closing the IGV (22) based on the operation of the gas turbine (10) and the temperature control system (11).

[0026] In a given embodiment, the controller (36) may function to control the operation of one or more heaters (28), evaporative cooling systems (26), and / or IGVs (22) based on feedback from an operator (e.g., via an I / O device (44)) and / or sensors (46) coupled to the intake section (14), compressor section (16), combustion section (18), turbine section (20), and / or generator (24). For example, the sensors (46) may include temperature sensors, pressure sensors, humidity sensors, exhaust emission sensors, vibration sensors, gap sensors, flame sensors, or any combination thereof. As a further example, the sensors (46) in the intake section (14) and / or compressor section (16) may monitor the temperature, pressure, and humidity of the airflow (9). The sensors (46) in the combustion section (18) may monitor the temperature and pressure of the incoming fuel and air, the temperature and pressure of the combustion gas, and the emission level in the combustion gas. For example, the emissions may include, in particular, nitrogen oxide (NOx), sulfur oxide (SOx), carbon dioxide (CO2), carbon monoxide (CO), and particulate matter. Similarly, a sensor (46) within the turbine section (20) may monitor the temperature, pressure, and emission levels within the high-temperature combustion gas, vibrations in the turbine section (20), the gap between the rotating and stationary parts, and the power output by the turbine section (20). A sensor (46) coupled to the generator (24) may monitor the electrical output, the temperature of the generator (24), the grid stability of the power grid, and other parameters associated with the operation of the generator (24). It should be noted that the location of the sensor (46) illustrated in FIG. 1 is intended to be exemplary and non-limiting. That is, the sensor (46) may be placed at one or more of the illustrated locations as well as at any other location within the gas turbine system (10). A temperature control system (11) may be configured to regulate the temperature of the intake air based on sensor input from any of the sensors (46).

[0027] FIG. 2 is a diagram of one embodiment of an evaporative cooling system (26) having a plurality of evaporative coolers (27). In a given embodiment, a temperature control system (11) may selectively enable or disable one or more of the plurality of evaporative coolers (27) to change the cooling capacity of the evaporative cooling system (26). In the illustrated embodiment, each evaporative cooler (27) of the evaporative cooling system (26) includes a fluid tank (48) for storing a cooling fluid (e.g., water), and an evaporative cooling medium (50) for placing the cooling fluid in a heat exchange relationship with the air received by the air intake section (14).

[0028] When in operation, the cooling fluid exits the fluid tank (48) through a pump suction line (52) that supplies the cooling fluid to the pump (54). The cooling fluid exits the pump (54) through a supply line (56) through which the cooling fluid flows through a flow meter (58). As illustrated in the illustrated embodiment, a primary line (60) and a secondary line (62) in parallel with the primary line (60) are positioned downstream of the flow meter (58). The secondary line (62) includes an orifice plate (64) capable of controlling the flow of the cooling fluid flowing from the supply line (56). Additionally, the secondary line (62) may include one or more additional valves (66) (e.g., trim valves). As illustrated, the secondary line (62) joins the primary line (60) at a union (68). However, in other embodiments, the evaporative cooling system (26) may not include a secondary line (62), a flow meter (58), and an orifice plate (64). In either case, the flow of cooling fluid from the pump (54) may flow into the evaporative cooling medium (50), where the cooling fluid is absorbed by the evaporative cooling medium (50) and the evaporative cooling medium (50) is consequently wetted as described above. In some embodiments, a collector pan (70) may be located downstream of the evaporative cooling medium (50). The collector pan (70) may collect any residual cooling fluid flowing from the evaporative cooling medium (50) and provide the flow of cooling fluid to a drain line (72) that supplies the fluid back into the fluid tank (48).

[0029] In a given embodiment, each evaporative cooler (27) of the evaporative cooling system (26) may include a plurality of evaporative cooling media (50), wherein each evaporative cooling media (50) has one or more supply lines (56) configured to provide cooling fluid from one or more fluid tanks (48). The evaporative cooling media (50) may be arranged in series or in parallel. The evaporative cooling media (50) facilitate evaporative cooling to help cool the intake air (9) in the intake section (14). For example, each evaporative cooler (27) of the evaporative cooling system (26) may include two, three, four, five, or more of the supply lines (56) and evaporative cooling media (50). It should be noted that such an embodiment may enable the gas turbine system (10) to operate at a desired power output under a wider range of operating temperatures, such as extreme high and low temperatures. For example, the evaporative cooling system (26) may be configured to selectively enable or disable one or more of the evaporative coolers (27) and / or one or more of the evaporative cooling media (50) within each of the evaporative coolers (27).

[0030] It should be noted that in a given embodiment, a controller (e.g., a controller (36) as discussed above with respect to FIG. 1) may function to control the operation of the pump (54) and / or the flow meter (58). Furthermore, in at least some cases, the controller (36) may receive measurements from one or more sensors (46) that can provide an indication of the operation of the evaporative cooling system (26), such as whether the pump (54) is operating and / or the level of the cooling fluid in the fluid tank (48). Additionally, the controller (36) may receive flow measurements from the flow meter (58). In either case, as discussed in more detail with respect to FIG. 4, the controller (36) may use these measurements to control the operation of both the cooling system (13, 26) and the variable heating system (12).

[0031] FIG. 3 is a diagram of one embodiment of a variable heating system (12) of the temperature control system (11) of FIG. 1, further illustrating various heaters (28) configured to heat the air (9) received by the air intake section (14). For example, the heaters (28) may include a heated fluid injector (74), an electric heater (76), and a heat exchanger (78). Although only one heated fluid injector (74), one electric heater (76), and one heat exchanger (78) are illustrated, a certain embodiment of the variable heating system (12) may include any number (e.g., one, two, three, four, five, or more) of heated fluid injectors (74), electric heaters (76), and / or heat exchangers (78) at one or more of the axial positions (30, 32, and / or 34) within the air intake section (14) as illustrated in FIG. 1.

[0032] In a given embodiment, a plurality of identical or different heaters (28) (e.g., heated fluid injector (74), electric heater (76), and / or heat exchanger (78)) may be arranged in series and / or parallel with respect to the direction of airflow through the air intake section (14). If the variable heating system (12) includes different heaters (28) (e.g., 74, 76, and / or 78) arranged in series as shown in FIG. 3, the different heaters (28) may be arranged in any order. In a given embodiment, any of the heaters (28) (e.g., 74, 76, and / or 78) may be located at a first, second, third, fourth, fifth, or subsequent position in the sequence of heaters (28), and any of the heaters (28) (74, 76, and / or 78) may be located at an axial position (30, 32, and / or 34) shown in FIG. 1. For example, each of the heaters (28) (e.g., 74, 76, and / or 78) may be located near a downstream portion (80) of the air intake section (14), an upstream portion (82) of the air intake section (14), or an intermediate portion (83) of the air intake section (14) between the downstream portion (80) and the upstream portion (82).

[0033] It should be noted that the relative position of one or more heaters (28) (e.g., 74, 76, and / or 78) to the evaporative cooling system (26) may provide certain advantages. For example, when one or more heaters (28) are positioned close to the upstream portion (82) (e.g., at the axial position (30) upstream of the evaporative cooling system (26) as shown in FIG. 1), the variable heating system (12) may allow the IGV (22) to maintain a position for the desired power output. However, additional heat (e.g., increased temperature of the airflow (9), thereby reducing relative humidity) may increase the water consumption of the evaporative cooling system (26), potentially reducing efficiency and / or performance and / or increasing costs. When one or more heaters (28) are positioned close to the downstream portion (80) (e.g., at an axial position (34) downstream of the evaporative cooling system (26) as shown in FIG. 1), the variable heating system (12) can also enable the IGV (22) to maintain a position for the desired power output. However, additional heat (e.g., increased temperature of the airflow (9)) will not increase the water consumption of the evaporative cooling system (26) because heat will be added after the airflow (9) has been cooled by the evaporative cooling system (26).

[0034] The heated fluid injector (74) comprises a circuit (84) that can be selectively coupled to a flow path of a heated fluid (86) (e.g., air, exhaust gas, an inert gas such as nitrogen, water such as steam, or any combination thereof) through a corresponding valve (88). In a given embodiment, the heated fluid (86) may include a waste heat source to improve the efficiency of a plant, e.g., a power plant. The waste heat may include, for example, exhaust gas from a turbine section (20), a furnace, a boiler, or other combustion system. The heated fluid injector (74) may include one or more fluid nozzles coupled to the wall of the air intake section (14), a grid of perforated fluid conduits within the air intake section (14), a grid of fluid conduits having fluid nozzles within the air intake section (14), or any combination thereof. As used herein, each flow path comprises a conduit that directs the heated fluid along a predetermined path between the components of the variable heating system (12).

[0035] Additionally, the heated fluid injector (74) includes a heated fluid outlet (90) capable of providing the heated fluid (86) to the air intake section (14) to mix with the air from the surrounding environment and heat the air from the surrounding environment. Thus, by directly injecting the heated fluid (86) into the air flow (9), the heated fluid injector (74) can be considered as a direct heating unit. In a given embodiment, the variable heating system (12) may include a plurality of heated fluid injectors (74), each comprising two or more of the circuits (84), each configured to inject the heated fluid (86) into the air intake section (14) to exchange heat between the air flow (9) received from the surrounding environment by the air intake section (14) and the heated fluid (86). For example, the heated fluid injector (74) may include two, three, four, five, or more of the circuits (84) (circuits (84a, 84b, 84c) are illustrated in FIG. 3).

[0036] In some embodiments, the heated fluid (86) may be thermally coupled to a heat source (92) (e.g., an electric heater, a combustion system such as a furnace, etc.) configured to raise the temperature of the heated fluid (86) in response to a control signal received by the controller (36). For example, the controller (36) may receive feedback indicating the ambient temperature of the air in the surrounding environment via a sensor (46) and may control the temperature of the heated fluid (86) by adjusting (e.g., increasing or decreasing) the current output by the heat source (92) based on this feedback. In other embodiments, the heat source (92) may continuously heat and / or maintain the temperature of the heated fluid (86) at a predetermined temperature. Although only one heated fluid injector (74) is illustrated, it should be noted that in at least some embodiments, the variable heating system (12) may include a plurality of heated fluid injectors (74) arranged in series, in parallel, or both.

[0037] During operation, the variable heating system (12) (e.g., controller (36)) selectively combines one or more of the circuits (84a, 84b, 84c) with the heated fluid injector (74) through the valves (88a, 88b, 88c) based on operating parameters of the gas turbine system (10), such as ambient temperature, relative humidity, compressor inlet temperature, plant output load, gas turbine exhaust temperature, compressor discharge temperature, combustor ignition temperature, steam temperature, steam flow, or any combination thereof. For example, the controller (36) may receive feedback indicating the temperature of the air flow (9) through the sensor (46) and, based on this feedback, may selectively adjust the position of the valves (88a, 88b, and / or 88c) (e.g., open, partially open, partially closed, or fully closed). In a given embodiment, a single valve may combine two or more of the circuits (84a, 84b, 84c), and thus, adjusting the position of the valve (88) may allow the heated fluid (86) to flow through a plurality of circuits (84). In any case, when one or more of the circuits (84a, 84b, 84c) are fluidly coupled to the heated fluid (86) through the valves (88a, 88b, 88c), the circuits (84a, 84b, 84c) may provide flow of at least a portion of the heated fluid (86) to the air intake section (14) through the heated fluid outlets (90a, 90b, 90c).

[0038] An electric heater (76) (e.g., a heating coil) is electrically coupled to a power supply unit (94). During operation, the power supply unit (94) may provide current to a heating element (77) (e.g., a resistor) of the electric heater (76). The heating element (77) converts the current into heat, thereby raising the temperature of the airflow (9) within the air intake section (14). Although only one heated electric heater (76) is illustrated, it should be noted that in at least some embodiments, the variable heating system (12) may include a plurality of electric heaters (76) arranged in series, in parallel, or both.

[0039] The heat exchanger (78) includes a circuit (84) that can be optionally coupled to the flow path of the heat transfer fluid (96). The heat exchanger (78) may include a shell and tube heat exchanger, a plate and shell heat exchanger, a plate fin heat exchanger, a spiral coil heat exchanger, or any suitable heat exchanger for the air intake section (14). For example, the heat exchanger may include one or more tubes (79) having fins (81), wherein the heat transfer fluid (96) passes through the tubes (79) and the air flow (9) passes around the tubes (79) along the fins (81), thereby indirectly transferring heat from the heat transfer fluid (96) to the air flow (9).

[0040] In a given embodiment, the variable heating system (12) may include a plurality of heat exchangers (78), each of which includes two or more circuits (84) configured to exchange heat between a heat transfer fluid (96) within each circuit and an air flow (9) passing through or over the circuit (84). For example, the heat exchanger (78) may include two, three, four, five, or more of the circuits (84). As illustrated, the heat exchanger (78) includes three circuits (84d, 84e, 84f) each coupled to a respective valve (88d, 88e, 88f). The heat exchanger (78), one or more circuits (84), and each valve (88) are collectively referred to as a heat exchanger system that is part of the variable heating system (12). Additionally, each of the circuits (84) illustrated in FIG. 4 is a single-pass circuit, but in other embodiments, one or more of the circuits (84) may be double-pass or multi-pass circuits. Although only one heat exchanger (78) is illustrated, it should be noted that in at least some embodiments, the variable heating system (12) may include a plurality of heat exchangers (78) arranged in series, in parallel, or both.

[0041] During operation, the variable heating system (12) (e.g., controller (36)) selectively connects one or more of the circuits (84d, 84e, 84f) to the heat exchanger (78) via valves (88d, 88e, 88f) based on operating parameters of the gas turbine system (10), such as ambient temperature, relative humidity, compressor inlet temperature, plant output load, gas turbine exhaust temperature, compressor discharge temperature, combustor ignition temperature, steam temperature, steam flow, or any combination thereof. For example, the controller (36) may receive feedback indicating the temperature of the air flow (9) via a sensor (46) and may selectively adjust the position of the valves (88d, 88e, and / or 88f) based on this feedback. In a given embodiment, at least one of the circuits (84d, 84e, 84f) may not include a valve (88), and thus is an uninterrupted connection that allows the heating fluid to flow continuously through at least one circuit (84d, 84e, 84f) of the heat exchanger (78) during the operation of the variable heating system (12). In another embodiment, each of the circuits (84) includes a corresponding valve (88). In yet another embodiment, a single valve (88) may fluidly connect multiple circuits (84) to the heat exchanger (78).

[0042] FIG. 4 is a flowchart illustrating an embodiment of a process (98) for operating a temperature control system (11) including a variable heating system (12) and a cooling system (13, 26) as discussed above with reference to FIGS. 1 through 3. It should be understood that the steps discussed herein are merely illustrative, and that certain steps may be omitted or performed in a different order than that described below. In some embodiments, the process (98) may be stored in memory (40) and / or storage (42) and executed by the processor (38) of the controller (36), or stored in another suitable memory and executed by another suitable processing circuit or a separate suitable processing circuit associated with the gas turbine system (10).

[0043] As illustrated in the exemplary embodiment of FIG. 4, in block (100), the processor (38) receives feedback indicating operating parameters of the gas turbine system (10). In the exemplary embodiment, the operating parameters may include the temperature of the ambient air or intake air into the air intake section (14) and / or into the compressor section (16). For example, the air temperature may be measured upstream of the cooling system (13, 26) and / or IGV (22), or downstream of it. Alternatively or additionally, the operating parameters may include the surface temperature and / or component temperature of the cooling system (13, 26) and / or IGV (22). The temperature feedback mentioned above may be used to help control the temperature of the intake air for power enhancement. In a given embodiment, the operating parameters may also include ambient conditions (e.g., relative humidity, ambient temperature, etc.), operating parameters of the gas turbine system (10) (e.g., position of the inlet guide vane (22), discharge temperature or pressure from the compressor section (16), fuel / air ratio in the combustion section (18), flame temperature, fuel efficiency or consumption, exhaust emission level, power output by the gas turbine system (10), load on the gas turbine system (10), etc.) and / or operating conditions of other related systems, such as a steam turbine in a combined cycle power plant (e.g., steam temperature, steam pressure, steam flow, etc.). Generally, the operating parameters may be any parameters indicating the need to control the temperature of the intake air into the air intake section (14) of the gas turbine system (10).

[0044] In some embodiments, before or during block (100), the processor (38) may receive an input indicating the desired power output of the gas turbine system. For example, the processor (38) may receive feedback indicating the ambient temperature and / or relative humidity of the ambient environment, a temperature threshold, and / or a humidity threshold. Subsequently, the processor (38) may determine the current power output based on such feedback. For example, memory (40) and / or storage (42) may store a lookup table and / or lookup plot containing the power output based on the ambient temperature and / or humidity associated with the ambient environment and / or components of the gas turbine system (10). In such embodiments, the processor (38) may determine whether the current power output of the gas turbine system is greater than or less than the desired power output of the gas turbine system, as generally discussed with respect to block (102).

[0045] In some embodiments, a lookup table and / or a lookup plot may enable the processor (38) to determine the current power output of the gas turbine system (10) when the evaporative cooling system (26) is active. A given evaporative cooling system may not have a partial load operating point, and thus it may be advantageous to use the evaporative cooling system (26) to cool the ambient air (e.g., for power boosting), but it should be noted that the evaporative cooling system (26) may supercool the air.

[0046] When feedback indicating operating parameters is received by the processor (38), the processor (38) may compare such feedback with a threshold range, as shown in block (102). The threshold range may be determined by the operator during the manufacture of the variable heating system (12). Additionally, or alternatively, the threshold may be determined through experimental testing and stored in the memory (40) of the controller (36). Additionally, the threshold range may be a threshold value. That is, the processor (38) may determine whether the feedback is greater or less than the threshold value rather than within the threshold range. As some non-limiting examples, the threshold value or threshold range may be a threshold position of the IGV (e.g., maximum or minimum position), a temperature threshold, a humidity threshold, a power output (MW) threshold, etc. Generally, the threshold may be any threshold range or threshold value associated with the performance and / or capacity of the gas turbine system (10), the ambient environment, or both.

[0047] In a given embodiment, the processor (38) may compare feedback, such as the current power output, with a desired power output or a desired power output range. In an illustrated embodiment, the processor (38) may compare the feedback (e.g., ambient air temperature, air flow (9), and / or temperature in the cooling system (13, 26) or IGV (22)) with a temperature threshold. For example, the temperature threshold may correspond to a temperature at which the gas turbine system (10) can achieve a desired power output. In a given embodiment, the process (98) may evaluate the feedback (e.g., measured temperature) for a plurality of temperature thresholds that may correspond to different locations and / or components (e.g., ambient air, temperature in the cooling system (12, 26), and temperature in the IGV (22)). The process (98) may also evaluate the feedback (e.g., measured temperature) for a plurality of temperature thresholds, each of which may trigger a different control action depending on the severity of the temperature.

[0048] In block (104), the processor (38) of the controller (36) provides a control signal suitable for the cooling system (13) (e.g., evaporative cooling system (26)) according to the cooling requirements in the gas turbine system (10). For example, the processor (38) of the controller (36) can selectively control the evaporative cooling system (26) to operate when power boosting is required (i.e., "on" condition) or to stop when power boosting is not required (i.e., "off" condition). However, in the illustrated embodiment, the processor (38) of the controller (36) may be configured to control the evaporative cooling system (26) to operate continuously under normal conditions, because the variable heating system (12) may be used to control the temperature of the air flow (9) that is cooled by the evaporative cooling system (26).

[0049] In block (106), the processor (38) of the controller (36) provides a control signal suitable for the variable heating system (12) to control the temperature of the intake air, regardless of whether it is cooled by the cooling system (13, 26). For example, in an embodiment where the cooling system (13) (e.g., evaporative cooling system (26)) operates continuously during the operation of the gas turbine system (10), the variable heating system (12) may be controlled to control the temperature of the intake air cooled by the cooling system (13) to increase the temperature of the intake air when the temperature falls below one or more temperature thresholds, for example as discussed above. Accordingly, the processor (38) of the controller (36) controls the variable heating system (12) by controlling the heater (28) and, for example, by transmitting a control signal to the valve(s) (88) of the heated fluid injector (74) and / or heat exchanger (78) (e.g., as described above with respect to FIG. 3). Alternatively or additionally, the processor (38) provides a control signal suitable for a power supply (94) electrically coupled to an electric heater (76) that thereby generates heat within the air intake section (14). In some embodiments, the controller (36) may provide a signal suitable for a pump coupled to one of the circuits (84) to control the flow rate of the heated fluid (86) or heat transfer fluid (96) based on feedback.

[0050] In some embodiments, the processor (38) may provide a control signal suitable for the variable heating system (12) based on the desired power output of the gas turbine system (10). That is, the processor (38) may determine the amount of heat to be supplied using the variable heating system (12) to produce the desired power output based on a lookup table or plot stored in the feedback and / or memory (40) and / or storage (42). In at least some cases, the processor (38) may determine the amount of heat to be supplied based on the presence and / or operation of the evaporative cooling system (26). In this way, the disclosed variable heating system (12) may enable the gas turbine system (10) to operate more efficiently, even when implementing a certain evaporative cooling system (26) capable of supercooling the air by supplying heat to the airflow (9) and changing the temperature of the airflow (9) to an amount associated with the desired power output.

[0051] The technical effect of the present system and method is to improve the performance of the gas turbine system by enabling the continuous operation of the cooling system (13) (e.g., evaporative cooling system (26)) within the air intake section (14) to help increase the efficiency and / or power output of the gas turbine system (10) while controlling the temperature of the intake air through the variable heating system (12) to achieve a target temperature. The target temperature of the intake air may be the lowest possible temperature based on a lower temperature threshold, or the target temperature may fall within a temperature range having an upper temperature threshold and a lower temperature threshold. The target temperature may be selected to achieve the desired power output of the gas turbine system. The target temperature may also be selected to allow the IGV (22) to be maintained in a desired position (e.g., open position), which may not otherwise be possible if the cooling system (13) supercools the intake air.

[0052] In a given embodiment, the variable heating system (12) may be modified into a gas turbine system (10) having an evaporative cooling system (26), or the variable heating system (12) and the cooling system (13) (e.g., the evaporative cooling system (26)) may be installed collectively within a new gas turbine system (10). In either case, the variable heating system (12) may control (e.g., increase or decrease) the temperature of the air cooled by the evaporative cooling system (26) before the air is compressed within the compressor section (16).

[0053] This description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including manufacturing and using any device or system and performing any included method. The patentable scope of the invention is limited by the claims and may include other examples that come to mind to a person skilled in the art. If such other examples have structural elements that are not different from the literal expression of the claims, or if they include equivalent structural elements that differ only slightly from the literal expression of the claims, such other examples are intended to be within the scope of the claims.

Claims

Claim 1 A system comprising a temperature control system (11) configured to be coupled to an air intake section (14) of a gas turbine system (10), wherein the gas turbine system (10) has a compressor section (16) fluidly communicating with the air intake section (14), and wherein the temperature control system (11) comprises a variable heating system (12) having one or more heaters (28) configured to heat the airflow in the air intake section (14) when the airflow is cooled by an evaporative cooling system (13, 26), and wherein the temperature control system (11) is configured to control the variable heating system (12) to change the amount of heat supplied by the one or more heaters (28) based on at least one temperature measurement for a temperature threshold, wherein the temperature threshold is selected to achieve a power output by the gas turbine at a predetermined level without at least partially closing the inlet guide vane (22) of the compressor section (16). Claim 2 A system comprising a temperature control system (11) configured to be coupled to an air intake section (14) of a gas turbine system (10), wherein the gas turbine system (10) has a compressor section (16) in fluid communication with the air intake section (14), and the temperature control system (11) comprises: an evaporative cooling system (13, 26) configured to cool an airflow in the air intake section (14); a variable heating system (12) having one or more heaters (28) configured to heat the airflow in the air intake section (14); and a controller configured to control the variable heating system (12) to change the amount of heat supplied by the one or more heaters (28) based on at least one temperature measurement for a temperature threshold, wherein the temperature threshold is selected to achieve a power output by the gas turbine at a predetermined level without at least partially closing the inlet guide vane (22) of the compressor section (16). Claim 3 In claim 1 or 2, the evaporative cooling system (13, 26) comprises one or more evaporative cooling media (50) configured to receive and evaporate a cooling liquid. Claim 4 A system according to claim 1 or 2, wherein one or more heaters (28) are arranged in series, in parallel, or in a combination thereof. Claim 5 A system according to claim 1 or 2, wherein the one or more heaters (28) are positioned upstream of the evaporative cooling system (13, 26), positioned downstream of the evaporative cooling system (13, 26), or positioned in common with the evaporative cooling system (13, 26) or integrated therewith. Claim 6 A system according to claim 1 or 2, wherein the one or more heaters (28) comprise at least one of a fluid injector (74), an electric heater (76), or a heat exchanger (78). Claim 7 A system according to claim 1 or 2, wherein the evaporative cooling system (13, 26) is configured to cool the airflow to increase the power output by the gas turbine system (10). Claim 8 A system according to claim 1 or 2, wherein the variable heating system (12) is configured to heat the airflow to offset the cooling by the evaporative cooling system (13, 26), in order to avoid closing the inlet guide vane (22) of the compressor section (16) of the gas turbine system (10), to reduce the amount of closing of the inlet guide vane (22), or both. Claim 9 A system comprising the air intake section (14) having the temperature control system (11) in claim 1 or 2. Claim 10 In claim 9, a system comprising the gas turbine system (10) having the air intake section (14). Claim 11 A method for controlling a temperature control system (11) to control the temperature of an airflow in an air intake section (14) of a gas turbine system (10), wherein the gas turbine system (10) has a compressor section (16) in fluid communication with the air intake section (14), and the method comprises: a step of controlling an evaporative cooling system (13, 26) to cool the airflow in the air intake section (14); and a step of controlling a variable heating system (12) having one or more heaters (28) to heat the airflow in the air intake section (14) - the step of controlling the variable heating system (12) includes a step of changing the amount of heat supplied by the one or more heaters (28) based on at least one temperature measurement for a temperature threshold - wherein the temperature threshold is selected to achieve a power output by the gas turbine at a predetermined level without at least partially closing the inlet guide vane (22) of the compressor section (16). Claim 12 In claim 11, the step of controlling the evaporative cooling system (13, 26) includes the step of cooling the airflow to increase the power output by the gas turbine system (10). Claim 13 In claim 12, the step of controlling the variable heating system (12) includes the step of heating the airflow after the airflow has been cooled by the evaporative cooling system (13, 26). Claim 14 In claim 11, the step of controlling the variable heating system (12) comprises changing the amount of heat based on at least one relative humidity measurement for a humidity threshold. Claim 15 A method according to claim 11, wherein the step of controlling the variable heating system (12) includes the step of heating the airflow to offset the cooling by the evaporative cooling system (13, 26) in order to avoid closing the inlet guide vane (22) of the compressor section (16) of the gas turbine system (10).

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