Exhaust duct for gas turbine engines

Abstract

To provide an exhaust duct for a gas turbine engine, which is useful for recovering exhaust heat from exhaust gas of the gas turbine engine without expense and additional space required for providing a heat recovery steam generator.SOLUTION: There is disclosed an exhaust duct for a gas turbine engine 50, which comprises a silencer section 12. At least two plate-shaped silencer baffles 20 are provided inside the silencer section 12. At least one of the plate-shaped silencer baffles is configured as a heat exchange device in that it comprises at least one internal cavity suitable for receiving a heat exchange fluid and leakproof with respect to the interior of the exhaust duct, in which the at least one internal cavity is fluidly connected to the outside of the exhaust duct at an inlet port and an outlet port.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present disclosure relates to an exhaust duct for a gas turbine engine of the type recited in the claims.

Background Art

[0002] The exhaust gas of a gas turbine engine is still several hundred degrees Celsius after leaving the expansion turbine and can typically be in the range of 500°C to 600°C under high partial load and full load conditions in modern gas turbine engines. Therefore, due to the exhaust gas, the large enthalpy flow that was added when burning fuel before expanding in the expansion turbine is discharged into the atmosphere and lost for technical use. The resulting enthalpy loss has an adverse effect on efficiency.

[0003] It is known in the art to recover the exhaust enthalpy of a gas turbine engine with a heat recovery steam generator and use the steam thus generated in a steam turbine to generate electricity. The steam can also be used for industrial purposes. However, constructing a combined cycle power generation plant in which a steam turbine as a bottoming cycle uses the exhaust energy from a gas turbine engine requires a large capital investment, which, despite excellent overall efficiency, is economically attractive only if the plant can be operated, for example, for more than 5000 hours per year and at a high output of at least 75% of the rated output, at least essentially as a base load power generation plant. Furthermore, a number of facilities inside the exhaust duct result in additional pressure losses and thus reduce the efficiency and output of the gas turbine engine itself. In addition, a heat recovery steam generator requires space that is not always available. In particular, the installation of a heat recovery steam generator may not be an option for adding to an existing single cycle gas turbine engine power plant.

[0004] U.S. Patent Application Publication No. 2013 / 0327052 teaches how to connect multiple gas turbine engines to a common stack and place a heat exchanger in the common stack. Furthermore, the document teaches how to improve heat transfer from the exhaust gas to the heat exchanger by providing a heat exchanger in the common stack, introducing non-laminar flow through a common exhaust stack, and applying dew point control.

[0005] U.S. Patent No. 8,069,660 discloses a heat recovery system incorporated within a silencer chamber. According to the teachings of this document, the exhaust flow first enters a first silencer chamber and is then divided into two sub-flows. The first of the sub-flows is transported from the first silencer chamber to a second silencer chamber, and from there to a third silencer chamber. The second of the sub-flows bypasses the second silencer chamber and is directed directly to the third silencer chamber. Thus, the second sub-flow flows through a conduit positioned around the silencer chamber in a heat recovery channel formed between the inner housing and the heat recovery outer housing. The heat transfer fluid is guided through the heat recovery channel, exchanges heat with the exhaust gas in the silencer chamber through the inner wall, and exchanges heat with the second sub-flow of exhaust gas flowing through the conduit, as the heat transfer fluid flows around the conduit. The teachings of the document do not specifically refer to applications related to gas turbine engines.

[0006] U.S. Patent No. 3,235,001 teaches a combination of silencer and heat exchanger suitable for installation at the outlet or inlet of a combustion engine. The combination of silencer and heat exchanger comprises a housing. On the front side of the housing, a front panel partially closes the housing, leaving open a front inlet formed between the front panel and the outer panel of the housing. On the rear side of the housing, the interior of the housing is connected to the engine inlet, thereby forming a rear inlet around a duct that connects the interior of the housing to the engine inlet and the outer panel of the housing. Thus, the fluid flow can enter the interior of the housing through the rear and front inlets, deflected radially inward toward the center of the housing, and from there toward the engine inlet. A heat exchanger assembly is provided inside the housing, and the heat exchanger assembly comprises a tube with square fins on the outside, thereby improving the flow around the tube and the heat exchange between the tube and the tube. [Overview of the project]

[0007] The object of this disclosure is to provide means for enabling the recovery of exhaust heat from a gas turbine engine. A more specific object of the subject matter of this disclosure is to provide an exhaust duct for the type of gas turbine engine described first. In one embodiment, an exhaust duct for a gas turbine engine is provided that enables the recovery of waste heat from the exhaust gas without adding additional equipment inside the exhaust duct that would result in pressure loss. In another embodiment, the heat exchanger is integrated into existing equipment within the exhaust duct. In yet another embodiment, the heat exchanger is provided in a manner that minimizes additional capital investment.

[0008] This is achieved by the subject matter described in claim 1.

[0009] Further effects and benefits of the disclosed subject matter, whether or not explicitly mentioned, will become apparent upon consideration of the disclosures provided below.

[0010] Accordingly, an exhaust duct for a gas turbine engine is disclosed, comprising a silencer section having an inlet and an outlet, and a flow direction from the inlet to the outlet. The flow direction can be determined by geometric shape, aerodynamic design, etc. It is understood that the inlet is configured to be located closer to the exhaust outlet of the gas turbine engine than the outlet of the silencer section. At least two plate-shaped silencer baffles are provided inside the silencer section and are arranged parallel to each other. Each silencer baffle extends along the flow direction of the silencer section from its upstream edge to its downstream edge. Each of the at least two plate-shaped silencer baffles has a side that extends along the flow direction of the silencer section from its upstream edge to its downstream edge. The upstream edge is particularly rounded and can form a so-called "bullnose" of the baffle for aerodynamic reasons. The side of the silencer baffle extends further across the flow cross section of the silencer section. The two sides of two adjacent plate-shaped silencer baffles are positioned facing each other, forming an exhaust flow path between them. At least one of the plate-shaped silencer baffles is configured as a heat exchanger, in that it comprises at least one internal cavity suitable for receiving a heat exchange fluid. Those skilled in the art will understand that the internal cavity suitable for receiving the heat exchange fluid is leak-proof to the inside of the exhaust duct. The at least one internal cavity is fluidically connected to the outside of the exhaust duct at an inlet port and an outlet port. In particular, the inlet and outlet ports extend through one or more side walls of the exhaust duct.

[0011] A baffle configured as a heat exchange device may also be referred to as a heat exchange baffle or heat exchange silencer baffle below.

[0012] Within the framework of this disclosure, it should be noted that the use of the indefinite article "a" or "an" never specifies a singularity and does not preclude the presence of multiple specified members or features. Therefore, it should be read as meaning "at least one" or "one or more."

[0013] In embodiments, at least one internal cavity may be provided outside the exhaust duct, i.e., as at least one internal duct fluidly connected through the wall of the exhaust duct. In exemplary embodiments, at least one internal duct may extend adjacent to and along the leading edge of at least one plate-shaped silencer baffle, extending from an inlet port to an outlet port. Similarly, at least one internal duct may extend in a meandering shape inside at least one silencer baffle, extending from an inlet port to an outlet port.

[0014] In exemplary embodiments further disclosed herein, at least one side of a silencer baffle is provided as a side wall, each side wall provided as a hollow body having two sheets with a space left between the sheets, each of the sheets being perforated by a number of openings, the openings on the sheets of the side wall being connected by tubes bridging the space, thereby fluidly connecting the two opposing sides of the side wall through the tubes. The tubes do not necessarily have to have a circular cross-section. The connections of the tubes to the sheets are airtightly sealed with each sheet. Thus, cavities suitable for receiving heat exchange fluids are formed on the inside of the side wall and on the outside of the tubes in the space between the sheets.

[0015] In exemplary embodiments further disclosed herein, all internal cavities suitable for receiving a heat exchange fluid, i.e., all internal cavities of all silencer baffles configured as heat exchangers, having internal cavities suitable for receiving a heat exchange fluid, are connected to two common headers, and each internal cavity for the heat exchange fluid is fluidically connected to the two common headers. Given that the internal cavities are intended for the flow of the heat exchange fluid, the headers can be referred to as an inlet header and an outlet header.

[0016] A gas turbine engine is further disclosed, wherein the exhaust side of the expansion turbine is connected to an exhaust duct of the type described above. A power plant comprising at least one of the disclosed gas turbine engines, i.e., a power plant in which the expansion turbine is connected to an exhaust duct of the type described above, is further disclosed.

[0017] In addition to the gas turbine engine, the power plant may be equipped with a compressed air energy storage (CAES) system, where the inlet port of a silencer baffle configured as a heat exchanger is fluidically connected to a CAES storage tank, and the outlet port of the silencer baffle configured as a heat exchanger is fluidically connected to a CAES expansion turbine.

[0018] In further embodiments, the power plant may be essentially the type of power plant disclosed in U.S. Patent Application Publication No. 2019 / 0195131. The power plant includes a turbocharger in addition to a gas turbine engine, the turbocharger comprising at least one low-pressure compressor, at least one high-pressure compressor, and at least one turbine for driving the compressor. Each compressor may be located on a common shaft together with the individual turbines and driven by the individual turbines. The turbocharger may then comprise at least one low-pressure turbocharger and one or more high-pressure turbochargers, the compressors of the low-pressure turbochargers delivering fluid to the high-pressure compressors. For example, multiple low-pressure turbochargers may be arranged parallel to each other and in series with a single high-pressure turbocharger in order to use the same turbocharger while considering different volumetric flow rates of the high-pressure and low-pressure compressors. In other embodiments, one or more high-pressure compressors and one or more low-pressure compressors may be fluidically arranged so that the compressors of the low-pressure turbocharger deliver fluid to the high-pressure compressors, while being provided on a common shaft for driving the compressors, particularly having a single turbine. The compressor outlet of at least one low-pressure compressor is fluidically connected to the inlet port of a silencer baffle configured as a heat exchanger, and to the compressor inlet of at least one high-pressure compressor. An intercooler may be fluidically interposed between the compressor outlet of at least one low-pressure compressor and the compressor inlet of at least one high-pressure compressor. The outlet port of the silencer baffle configured as a heat exchanger is fluidically connected to the turbine inlet of at least one turbine of the turbocharger. The turbine outlet of at least one turbine of the turbocharger is fluidically connected to a back pressure control device, and the compressor outlet of at least one high-pressure compressor is connected to the working fluid passage of the gas turbine engine downstream of the compressor and upstream of the combustor of the gas turbine engine, i.e., fluidically connected to the combustor of the gas turbine engine.Therefore, the waste heat recovered in the heat exchange baffle can be used to drive an external compressor to supply additional air to the combustor of the gas turbine engine, thus increasing the turbine output of the gas turbine engine and / or reducing the flow through the compressor of the gas turbine engine, thus reducing the power consumption of the compressor of the gas turbine engine. Back pressure valves are used to control the discharge pressure of the high-pressure compressor of a turbocharger.

[0019] In yet another embodiment of the power plant disclosed herein, a silencer baffle configured as a heat exchanger is fluidly interposed between the compressor and combustor of a gas turbine engine through its inlet and outlet ports, thereby configured to receive at least a portion of the fluid flow from the compressor to the combustor. In a more specific embodiment, the compressor is an auxiliary compressor distinct from the compressor of the gas turbine engine, and the compressor is motor-driven in particular. During partial load operation, the compressor can charge a battery, which is used to power a motor to drive the auxiliary compressor during periods of high power demand and to boost the output of the gas turbine engine.

[0020] In the power plant embodiments disclosed herein, the gas turbine engine includes an intake preheating circuit comprising an intake preheating heat exchanger located upstream of the compressor of the gas turbine engine. One exemplary particular non-limiting embodiment of a gas turbine engine with an intake preheating heat exchanger is disclosed in U.S. Patent Application Publication No. 2018 / 0135467. Silencer baffles configured as heat exchangers are incorporated into the intake preheating circuit through their inlet and outlet ports, thereby allowing fluids contained in the intake preheating circuit to flow through an internal cavity for heat exchange fluids located inside the heat exchange silencer baffles. Such applications are found to be useful in improving the partial load efficiency of the gas turbine engine, or otherwise may allow the gas turbine engine to operate in normal operating mode at a low percentage of its ISO rated power.

[0021] In yet another embodiment of the power plant disclosed herein, the gas turbine engine includes a fuel preheating circuit, the fuel preheating circuit includes a fuel preheating heat exchanger located upstream of the combustor of the gas turbine engine in the fuel flow path. Silencer baffles configured as heat exchangers are incorporated into the fuel preheating circuit through their inlet and outlet ports, thereby allowing the fluid contained in the fuel preheating circuit to flow through an internal cavity for heat exchange fluid located inside the heat exchange silencer baffles.

[0022] In yet another embodiment of the power plant disclosed herein, the compressor of a gas turbine engine has an extraction port downstream of the compressor inlet and upstream of the compressor outlet. A first line extends from the extraction port to the low-pressure inlet port of an external compressor, thereby fluidically connecting the extraction port to the low-pressure inlet port of the external compressor. A second line is connected to the high-pressure outlet port of the external compressor, fluidly connecting the high-pressure outlet port of the external compressor to the inlet port of a silencer baffle configured as a heat exchanger. A third line is connected to the high-pressure outlet of the compressor of the gas turbine engine and to at least one of the combustors of the gas turbine engine, fluidly connecting the outlet port of the silencer baffle configured as a heat exchanger to the high-pressure outlet of the compressor of the gas turbine engine and / or the combustor of the gas turbine engine.

[0023] It will be understood that the features and embodiments described above can be combined with each other. Furthermore, it will be understood that further embodiments are conceivable within the scope of the present disclosure and the subject matter claimed, although these will be obvious and clear to those skilled in the art.

[0024] The subject matter of this disclosure is described in more detail hereby by selected exemplary embodiments shown in the accompanying drawings. The drawings are as follows: [Brief explanation of the drawing]

[0025] [Figure 1]Perspective view of an exemplary embodiment of an exhaust duct of a gas turbine engine. [Figure 2] Cross-sectional view of a silencer section of an exhaust duct of a gas turbine engine having a rectangular cross-section. [Figure 3] Cross-sectional view of a first exemplary embodiment of a heat exchange silencer baffle. [Figure 4] Cross-sectional view of a second exemplary embodiment of a heat exchange silencer baffle. [Figure 5] Perspective view of a third exemplary embodiment of a heat exchange silencer baffle. [Figure 6] Another cross-sectional view of the baffle illustrated in FIG. 5. [Figure 7] Portion of a heat exchange silencer section of an exhaust duct in an isometric view, outlining the connection of heat exchange baffles to inlet and outlet headers. [Figure 8] Schematic diagram of an embodiment of a power plant comprising a gas turbine engine and a compressed air energy storage plant, using a heat exchange silencer section of the exhaust duct of the gas turbine engine to preheat the working fluid of the compressed air energy storage plant. [Figure 9] Schematic diagram of an embodiment of a power plant with turbocharger drive air injection, using a heat exchange silencer section of the exhaust duct of a gas turbine engine to supply energy for driving a turbocharger. [Figure 10] Schematic diagram of an embodiment of a power plant with an external motor-driven booster compressor, using a heat exchange silencer section of the exhaust duct of a gas turbine engine to preheat air from an external compressor. [Figure 11] Schematic diagram of an embodiment of a power plant with gas turbine intake preheating, using a heat exchange silencer section of the exhaust duct of a gas turbine engine to provide heat to an intake air preheater. [Figure 12] Schematic diagram of a further embodiment of a gas turbine power plant, using a heat exchange silencer section of the exhaust duct of a gas turbine engine to preheat air extracted from the compressor of the gas turbine engine. [Modes for carrying out the invention]

[0026] It should be understood that the drawings are highly schematic, and details not necessary for explanation have been omitted to facilitate understanding and depiction. The drawings show only selected exemplary embodiments, and it should be further understood that embodiments not shown are within the scope disclosed herein and / or the subject matter claimed.

[0027] The subject matter described herein will be better understood by those skilled in the art through the exemplary embodiments shown in the accompanying drawings and outlined below. It should be understood that these exemplary embodiments are provided solely for illustrative purposes to enable a better understanding of the subject matter described herein and are not intended to limit the subject matter outlined in the claims.

[0028] Figure 1 shows an example of an exhaust duct 1 for a gas turbine engine. The exhaust duct 1 comprises a stack 10. An exhaust duct transition section 11 is configured to connect to the downstream end of a gas turbine engine 50 (Schematically shown in Figures 8 to 12). The silencer section 12 of the exhaust duct comprises a silencer baffle 20, which can be seen in this partial cross-sectional view. In the illustrated example, the stack 10 and the silencer section 12 have rounded cross-sections, and the exhaust duct transition section 11 is shown with a rectangular cross-section. However, it is quite possible for either the stack 10 or the silencer section 12 to have a rectangular cross-section, and the exhaust duct transition section 11 may have a rounded or circular cross-section. Similarly, although the silencer section 12 is exemplified as being located in the vertical section of the exhaust duct 1, the silencer section 12 may also be located in the horizontal section of the exhaust duct 1. These facts are readily apparent to those skilled in the art.

[0029] Figure 2 illustrates a cross-sectional view of a silencer section 12 having a rectangular cross-section as an example. The exhaust duct 1 is defined by a duct wall 13. As can be understood, the flow of exhaust gases within the silencer section 12 is perpendicular to the plane of the drawing. A number of silencer baffles 20 are arranged across the cross-section of the exhaust duct 1, essentially parallel to one another, so that two adjacent silencer baffles 20 form a flow path between them. According to the subject matter disclosed herein, at least one of the silencer baffles 20, and each of the silencer baffles 20 in some embodiments, is configured as a heat exchanger, or heat exchange silencer baffle, as will be outlined in more detail below.

[0030] Generally speaking, the silencer baffle 20 is configured as a heat exchanger in that it has at least one internal cavity suitable for receiving a heat exchange fluid. Those skilled in the art will understand that the internal cavity for receiving the heat exchange fluid is leak-proof to the inside of the exhaust duct 1, thereby preventing the heat exchange fluid from leaking from the internal cavity of the silencer baffle 20 into the exhaust duct 1. At least one internal cavity is fluidically connected to the outside of the exhaust duct 1. Figure 3 shows a cross-sectional view of a first exemplary embodiment of the silencer baffle 20 configured as a heat exchanger, the cross-section being perpendicular to the sides 25 and 26 of the baffle. The sides traverse the exhaust duct 1 in the silencer section 12 and extend along the flow direction of the silencer section 12 from the upstream edge 21 to the downstream edge. The flow of exhaust gas is from left to right in the drawing. In certain embodiments, the upstream edge 21 of the silencer baffle 20 is rounded to form a so-called bullnose section of the silencer section 12 in order to reduce aerodynamic drag and thus reduce pressure loss of the silencer baffle 20. In the illustrated embodiment, an internal cavity 22 suitable for receiving heat exchange fluid is provided in the bullnose section of the silencer baffle 20 as a duct extending along the front (or upstream) edge 21 of the silencer baffle 20. The duct 22 extends along the entire "span width" of the silencer baffle 20 and has an open end with a port, which extends through the wall of the exhaust duct 1 to allow the duct 22 to be in fluid communication with the outside of the exhaust duct 1 when the baffle 20 is installed in the silencer section 12. The port is not shown in this description but will be readily apparent to those skilled in the art. Downstream of the bullnose section, the baffle 20 is hollow between the side walls 250 and 260. Sides 25 and 26 are located outside side walls 250 and 260, respectively.

[0031] Figure 4 shows a second embodiment of a silencer baffle 20 configured as a heat exchanger, in a cross-section parallel to the main surface of the baffle 20. In this exemplary embodiment, the internal cavity 22 is provided as a duct that winds inside the baffle between the sides 25, 26. The duct 22 is fluidly connected to ports 23 and 24, which can be called an inlet port and an outlet port, respectively. The type of heat exchange duct illustrated in Figure 4 may also be provided in the inner lining of an exhaust stack wall 13, which is illustrated, for example, in Figure 2 above or in Figure 7 below. Although the duct inside the exhaust stack wall is not explicitly shown, it will be readily apparent to those skilled in the art from this disclosure.

[0032] It will be understood that both types of ducts shown in Figures 3 and 4 can be combined into a single baffle 20.

[0033] In one embodiment shown in Figures 5 and 6, the side walls 250, 260 of the baffle 20 are provided as hollow bodies formed between sheets 251, 252, with space remaining between the sheets, with the side wall 250 being shown in more detail. Although only one hollow side wall 250 is shown, those skilled in the art will readily understand that the side wall 260 may be the same. The side wall 250 comprises sheets 251, 252 spaced apart from each other, such that the side wall 250 itself constitutes a hollow body. The side surface 25 of the baffle 20 is provided on the outside of the sheet 251.

[0034] Figure 6 shows a cross-sectional view of the side wall 250 in the line of sight designated by "VI-VI" in Figure 5. Each of the sheets 251 and 252 is perforated by a number of openings, and the openings on the two sheets 251 and 252 of the side wall 250 are aligned with each other. Each pair of opposing openings is connected by a tube 27 that bridges the space between the sheets 251 and 252. Thus, the tube 27 fluidly connects the two opposing sides of the side wall 250 through the tube 27. Furthermore, the tube 27 airtightly seals with each of the sheets 251 and 252, thereby forming a cavity 22 suitable for receiving heat exchange fluid in the space between the two sheets 251 and 252 and outside the tube 27.

[0035] Figure 7 shows a portion of the heat exchange silencer section 12 of the exhaust duct 1 in an isometric view, further illustrating the fluid connections of the heat exchange baffle 20. As outlined above, the baffle 20 is located in a portion of the exhaust duct 1 formed by the duct wall 13. Outside the exhaust duct, headers 28 and 29 are connected to the supply and return lines. Ports 23 and 24 extend through the duct wall 13 and connect to headers 28 and 29 an internal cavity 22 for receiving the heat exchange fluid inside the baffle 20. As is easily understood, there may be one port 23 and one port 24 associated with each heat exchange baffle 20. Needless to say, the number of heat exchange baffles 20 and the number of ports 23 and 24 may differ from those shown in the exemplary embodiment, respectively. Thus, the heat exchange baffle 20 is connected to the supply and return headers 28, 29.

[0036] A gas turbine engine 50 in which the exhaust side of the expansion turbine 53 is fluidly connected to a heat exchange silencer section 12 having one or more heat exchange silencer baffles 20 of any type outlined above, can be usefully applied to many applications, some of which are outlined in more detail below. It should be understood that the exemplary applications mentioned below are not exhaustive and are shown merely as examples.

[0037] Figure 8 illustrates a first exemplary embodiment of the use of the subject matter described above in a power plant. The power plant comprises a gas turbine engine 50 and a compressed air energy storage (also known as CAES) plant 100. The gas turbine engine 50 comprises a compressor 51, a combustor 52, and an expansion turbine 53, and is arranged to drive a generator 54. Exhaust gas 61 from the expansion turbine 53 is discharged through a stack 10. In the flow path of the exhaust gas 61, a silencer section 12 of the exhaust duct is located upstream of the stack 10. Inside the silencer section 12, a silencer baffle 20 is configured as a heat exchanger, as described above.

[0038] The CAES plant 100 comprises a compressed air storage tank 101, a main air heater 102, an expansion turbine 103, and a generator 104 driven by the expansion turbine 103. A heat exchange baffle 20 of the silencer section 12 is fluidically interposed between the compressed air storage tank 101 and the main air heater 102. This is achieved by the inlet port of the heat exchange silencer baffle 20 inside the silencer section 12 being fluidically connected to the compressed air storage tank 101, and the outlet port of the heat exchange silencer baffle 20 being fluidically connected to the expansion turbine 103 via the main air heater 102. Thus, the air discharged from the compressed air storage tank 101 flows through an internal cavity 22 for receiving heat exchange fluid inside the baffle 20 of the silencer section 12 before being supplied to the main air heater 102.

[0039] Therefore, when the gas turbine engine 50 and the CAES plant 100 are operating simultaneously, the air discharged from the compressed air storage tank 101 passes through the heat exchange baffle 20 inside the silencer section 12 and is heated by heat exchange with the gas turbine engine exhaust gas 61 before entering the main air heater 102, thereby cooling the gas turbine engine exhaust gas 61. This reduces the energy required to heat the air to a specific temperature within the main air heater 102, reducing the heat energy loss associated with the exhaust gas flow 61 through the stack 10, thereby improving the overall power plant efficiency. Depending on the thermal power requirements of the CAES plant 100, the heat exchange capacity of the heat exchange silencer section 12, and the match between the desired inlet temperature for the CAES expansion turbine 103 and the temperature to which the heat exchange silencer section 12 can heat the air discharged from the compressed air storage tank 101, the heat exchange silencer section 12 can function as the main air heater for the CAES plant, and therefore the heater 102 can be omitted. However, it should be noted that in a configuration without the CAES heater 102, the operation of the CAES plant 100 is entirely dependent on the operation of the gas turbine engine 50, whereas in the presence of the CAES heater 102, the CAES plant 100 can be operated independently of the gas turbine engine 50.

[0040] A second exemplary example of a power plant utilizing the heat exchange silencer arrangement disclosed herein is a gas turbine power plant with turbocharger-driven air injection, essentially as described in U.S. Patent Application Publication No. 2019 / 0195131, shown in Figure 9. In addition to the gas turbine engine 50, the power plant includes a turbocharger comprising a low-pressure turbocharger 70 and a high-pressure turbocharger 75 in the illustrated exemplary embodiment. The exemplary embodiment shows three low-pressure turbochargers and one high-pressure turbocharger. As will become apparent below, on the one hand, the mass flow rate through the compressor of the low-pressure turbocharger 70 is greater than the mass flow rate through the high-pressure turbocharger 75. Furthermore, due to the compression of air in the compressor 71 of the low-pressure turbocharger 70, the inlet flow of the compressor 76 of the high-pressure turbocharger 75 is smaller than the inlet mass flow rate of the compressor 71 of the low-pressure turbocharger 70, even with the same mass flow rate. Considering these effects when matching the number of low-pressure turbochargers, in principle, it becomes possible to use the same type of turbocharger for both the high-pressure turbocharger 75 and the low-pressure turbocharger 70.

[0041] The gas turbine engine 50 discharges exhaust gas from the expansion turbine 53 through the transition section 11 to the exhaust duct 1. The exhaust gas then passes through the heat exchange silencer section 12 and enters the stack 10. During operation, intake air 65 is compressed by the low-pressure compressor 71 and discharged from the low-pressure compressor as low-pressure compressed air 66. The compressor outlet of the low-pressure compressor 71 is fluidically connected to the inlet port of the heat exchange silencer baffle 20 located inside the heat exchange silencer section 12, and to the compressor inlet of the high-pressure compressor 76. Thus, the low-pressure compressed air 66 is divided into a first partial flow that enters the heat exchange silencer baffle 20 of the heat exchange silencer section 12, and a second partial flow that is supplied to the inlet of the high-pressure compressor 76 via the intercooler 73. The outlet port of the heat exchange silencer baffle 20, located inside the heat exchange silencer section 12, is fluidly connected to the turbine inlet of the expansion turbine 72 of the low-pressure turbocharger 70 and the turbine inlet of the expansion turbine 77 of the high-pressure turbocharger 75. Thus, heated low-pressure compressed air 67 from the heat exchange silencer section 12 is delivered to the expansion turbines 72 and 77, where it expands and is discharged as exhaust air 69. In expanding the heated low-pressure compressed air, the expansion turbines 72 and 77 generate power to drive the compressors 71 and 76.

[0042] The compressor outlet of the high-pressure compressor 76 is fluidically connected to the combustor 52 of the gas turbine engine 50. Thus, the high-pressure compressed air 68 from the high-pressure compressor 76 is delivered to the combustor 52 and added to the mass flow rate delivered to the combustor 52 by the compressor 51 of the gas turbine engine. Consequently, the expansion turbine 53 of the gas turbine engine can expand a larger mass flow rate than that delivered by the compressor 51. This configuration increases the mechanical power output from the expansion turbine 53 and / or reduces the power consumption of the compressor 51, resulting in more power being available to drive the generator 54 to generate electrical energy. The turbine outlet of the high-pressure expansion turbine 77 is fluidically connected to a back pressure control device 78, thus enabling control of the pressure of the high-pressure compressed air 68.

[0043] A further exemplary example of a power plant incorporating the subject matter described herein is shown in Figure 10, in which an external motor-driven compressor 111 is used to increase the output of a gas turbine engine 50. Such applications are found to be useful during both periods of low-grid and peak-grid power demand. For example, in the case of low-grid power demand, a battery is charged with electricity generated by a generator driven by the gas turbine engine 50. In the case of peak-grid power demand, the stored electrical energy can be used to drive a motor, which then drives the compressor 111. Generally, the compressor 111 compresses the intake air 65 and supplies the resulting additional compressed air to the gas turbine engine or combustor 52, essentially downstream or at the outlet of the compressor 51. In either case, the outlet of the compressor 111 is in fluid communication with the combustor 52.

[0044] In the embodiments described herein, the expansion turbine 53 of the gas turbine engine 50 discharges exhaust gas into an exhaust duct having a heat exchange silencer section 12 equipped with a heat exchange silencer baffle 20. The heat exchange silencer baffle 20 is fluidically interposed between the compressor 111 and the combustor 52 through its inlet and outlet ports and is configured to receive at least a portion of the fluid flow being transported from the compressor 111 to the combustor 52. Thus, compressed air 81 from the compressor 111 flows through the heat exchange silencer baffle 20 and is supplied to the gas turbine engine 50 downstream of the compressor 51 as heated compressed air 82.

[0045] A temperature sensor 115 detects the temperature of the heated compressed air 82 and transmits the temperature of the heated compressed air 82 to the controller 116. Through a control valve 113, the controller 116 controls the mass flow rate of the compressed air 81 through the heat exchange silencer baffle 20, adapting the mass flow rate of the compressed air 81 to the available heat to achieve a desired target temperature for the heated compressed air. A stop valve 112 allows the line for the compressed air 81 to be closed when the compressor 111 is not operating. Through heat exchange with the exhaust gas of the gas turbine engine 50, the compressed air 82 is introduced into the gas turbine engine 50 at a high temperature, and thus the temperature rise of the fraction of the gas turbine engine working fluid flow through the combustor 52 is reduced. Thus, fuel consumption of the gas turbine engine 50 is reduced by heating the auxiliary air 82 supplied to the gas turbine engine 50 by the compressor 111.

[0046] Another exemplary example of a power plant to which a gas turbine engine having the type of heat exchange silencer section described herein is applied to improve efficiency is shown in Figure 11. As described above, one exemplary particular non-limiting embodiment of a gas turbine engine with an intake preheating heat exchanger is disclosed in U.S. Patent Application Publication No. 2018 / 0135467. The gas turbine engine 50 comprises an intake preheating circuit, which comprises an intake preheating heat exchanger 56 located in the inlet housing 55 and upstream of the compressor 51 of the gas turbine engine 50 in the working fluid flow of the gas turbine engine 50. Intake preheating increases the power consumption of the compressor 51 of the gas turbine engine 50 but is known to be an efficient means when operating the gas turbine engine 50 at very low loads. As is well known to those skilled in the art, by changing the temperature of the intake 60, the relative output of the gas turbine engine 50 can be changed by a constant megawatt output. Thus, the operating point can be shifted to achieve good overall efficiency and improved emissions.

[0047] The heat exchange silencer baffles 20 are incorporated into the intake preheating circuit through their inlet and outlet ports, thereby allowing the fluid contained in the intake preheating circuit to flow through an internal cavity for the heat exchange fluid located inside the heat exchange silencer baffles 20. In a manner commonly known to those skilled in the art, the intake preheating circuit includes a pump 117 that transports fluid from a tank 118. The fluid is generally supplied from the pump through the heat exchange silencer baffles 20 located inside the heat exchange silencer section 12 of the exhaust duct.

[0048] During operation of the gas turbine engine, exhaust gases from the expansion turbine 53 flow through the heat exchange silencer section 12. Therefore, the fluid, transported by the pump 117 and flowing through the heat exchange baffle 20, is heated by heat exchange with the exhaust gases from the gas turbine engine 50, flows through the intake preheating heat exchanger 56, heats the intake air 60 flowing through the compressor 51 by heat exchange with water, and is returned to the tank 118. In the intake preheating circuit, a temperature sensor 115 is located downstream of the heat exchange silencer baffle 20 and connected to a controller 116. The controller 116 acts on a three-way control valve 114, which controls the flow of water through a bypass line that bypasses the heat exchange baffle 20, thereby controlling the temperature of the fluid entering the intake heat exchanger 56. It should be noted that the temperature sensor 115 may also be located in the flow of heated intake air 60 from the intake heat exchanger 56 to the compressor 51 of the gas turbine engine 50. In this way, the intake air temperature can be directly controlled. Furthermore, in the exemplary embodiments described herein, the intake preheating circuit includes a stop valve 112 for completely shutting off the fluid flow within the intake preheating circuit to avoid final thermally driven convection that may occur even if the pump 117 is shut off.

[0049] A very similar arrangement can be used to apply exhaust heat recovery in the heat exchange silencer baffle 20 for fuel preheating. In this case, the intake preheating heat exchanger 56 is simply replaced with a fuel preheating heat exchanger that is supplied with fuel instead of intake air.

[0050] A further exemplary embodiment of a gas turbine power plant utilizing the exhaust duct described herein, having a heat exchange silencer section, is shown in Figure 12. Partially compressed air is extracted from the compressor 51 of the gas turbine engine 50 at an extraction port downstream of the compressor inlet and upstream of the compressor outlet, and further compressed by an external compressor 111. The high-pressure outlet port of the compressor 111 is fluidically connected to the inlet port of the heat exchange silencer baffle 20. Thus, the compressed air from the external compressor 111 flows through the heat exchange baffle 20.

[0051] Further lines are connected to at least one of the high-pressure outlet of the compressor 51 and the combustor 52 of the gas turbine engine 50, thus fluidly connecting the outlet port of the heat exchange silencer baffle to the combustor of the gas turbine engine. Thus, exhaust heat from the gas turbine engine 50 is recovered and reintroduced into the gas turbine engine process. A temperature sensor 115 detects the temperature of the compressed air downstream of the heat exchange silencer baffle 20. The detected temperature is transmitted to a controller 116, which then controls a three-way control valve 114. The three-way control valve 114 allows a fraction of the compressed air from the compressor 111 to be bypassed around the heat exchange baffle 20, thus enabling control of the temperature of the compressed air downstream of the heat exchange silencer baffle 20. A stop valve 112 located in the extraction flow path allows the external flow path from the extraction port through the heat exchange silencer baffle 20 to the combustor 52 of the gas turbine engine 50 to be closed.

[0052] While the subject matter of this disclosure is illustrated by exemplary embodiments, it will be understood that these are not intended in any way to limit the scope of the claimed invention. The claims cover embodiments not expressly illustrated or disclosed herein, and embodiments that deviate from the embodiments disclosed in exemplary embodiments for carrying out the teachings of this disclosure will still be encompassed by the claims. [Explanation of Symbols]

[0053] 1. Exhaust duct 10 stacks 11 Exhaust duct transition section 12 Heat exchange silencer section 13 Duct walls, exhaust stack walls 20 Heat exchange silencer baffle 21 Upstream edge 22 Internal cavities, ducts 23 Entrance Port 24 Exit Ports 25 Side view 26 Side view 27 tube 28 Supply Header 29 Return Header 50 Gas turbine engine 51 Compressor 52 Combustor 53 Expansion Turbine 54 Generators 55 Entrance Housing 56 Intake preheating heat exchanger 60 Intake 61 Exhaust gas flow, gas turbine engine exhaust gas 65 Intake 66 Low-pressure compressed air 67 Low-pressure compressed air 68. High-pressure compressed air 69 Exhaust air 70 Low-pressure turbocharger 71 Low-pressure compressor 72 Expansion Turbine 73 Intercooler 75 High-pressure turbocharger 76. High-pressure compressor 77 High-pressure expansion turbine 78 Back pressure control device 81 Compressed air 82. Heated compressed air, auxiliary air 100 Compressed Air Energy Storage (CAES) Plant 101 Compressed air storage tank 102 Main air heater, CAES heater 103 CAES Expansion Turbine 104 Generator 111 External motor-driven compressor 112 Stop valve 113 Control valve 114 Three-way control valve 115 Temperature Sensor 116 Controllers 117 Pump 118 tanks 250 side wall 251 seats 252 seats 260 side wall

Claims

1. An exhaust duct (1) for a gas turbine engine (50), wherein the exhaust duct (1) comprises a silencer section (12), and the silencer section (12) has an inlet and an outlet, and a flow direction from the inlet to the outlet. At least two plate-shaped silencer baffles (20) are provided inside the silencer section (12) and are arranged parallel to each other, and each silencer baffle (20) extends along the flow direction of the silencer section (12) from the upstream edge (21) to the downstream edge. Each of the at least two plate-shaped silencer baffles (20) has sides (25, 26) extending from the upstream edge (21) to the downstream edge along the flow direction of the silencer section (12), and the two sides (25, 26) of two adjacent plate-shaped silencer baffles (20) are arranged facing each other, forming an exhaust passage between them. Furthermore, at least one of the plate-shaped silencer baffles (20) is configured as a heat exchanger such that at least one of the plate-shaped silencer baffles (20) has at least one internal cavity (22) suitable for receiving heat exchange fluid, and the at least one internal cavity (22) suitable for receiving heat exchange fluid is prevented from leaking fluid into the exhaust duct and is fluidly connected to the outside of the exhaust duct (1) at inlet and outlet ports (23, 24). Exhaust duct (1).

2. The exhaust duct (1) according to claim 1, wherein the at least one internal cavity (22) is provided as at least one internal duct fluidly connected to the outside of the exhaust duct (1).

3. The exhaust duct (1) according to claim 2, wherein at least one internal duct extends adjacent to and along the upstream edge (21) of at least one plate-shaped silencer baffle (20).

4. The exhaust duct (1) according to any one of claims 2 to 3, wherein at least one internal duct extends in a meandering shape inside at least one silencer baffle (20).

5. At least one side (25, 26) of the silencer baffle (20) is provided on a side wall (250, 260), and each side wall (250, 260) is provided as a hollow body having two sheets (251, 252) with a space remaining between the two sheets (251, 252), each of the sheets (251, 252) being perforated by a number of openings, and each aligned pair of openings on the sheets (251, 252) of the side wall (250, 260) is the space An exhaust duct (1) according to any one of claims 2 to 4, wherein the internal cavity (22) suitable for receiving a heat exchange fluid is formed in the space between the two sheets (251, 252) and outside the pipe (27), and is connected by a pipe (27) that bridges the space between the two sheets (251, 252) and seals airtightly with each of the sheets (251, 252), thereby fluidly connecting the two opposing sides of the side walls (250, 260) through the pipe (27).

6. The exhaust duct (1) according to any one of claims 1 to 5, wherein all internal cavities (22) suitable for receiving heat exchange fluids of all silencer baffles (20) configured as heat exchangers are connected to two common headers (28, 29), and each internal cavity (22) for the heat exchange fluid is fluidly connected to the two common headers (28, 29).

7. A gas turbine engine (50) comprising an expansion turbine (53) and an exhaust duct according to any one of claims 1 to 6, A gas turbine engine (50) in which the exhaust side of the expansion turbine (53) is connected to the exhaust duct (1).

8. A power plant comprising at least one gas turbine engine (50) as described in claim 7, further comprising a compressed air energy storage (CAES) system, wherein the inlet port (23) of the silencer baffle (20) configured as a heat exchanger is fluidly connected to a CAES storage tank, and the outlet port (24) of the silencer baffle (20) configured as a heat exchanger is fluidly connected to a CAES expansion turbine (103).

9. A gas turbine engine (50) according to claim 7, further comprising a turbocharger, the turbocharger comprising at least one low-pressure compressor (71), at least one high-pressure compressor (76), and at least one turbine (72, 77) for driving the compressors (71, 76), The compressor outlet of the at least one low-pressure compressor (71) is fluidly connected to the inlet port (23) of the silencer baffle (20) configured as a heat exchanger, and to the compressor inlet of the at least one high-pressure compressor (76). The outlet port (24) of the silencer baffle (20), which is configured as a heat exchanger, is fluidly connected to the turbine inlet of at least one turbine (72, 77) of the turbocharger. The turbine outlet of at least one turbine (72, 77) of the turbocharger is fluidly connected to a back pressure control device (78). The compressor outlet of at least one high-pressure compressor (76) is fluidly connected to the combustor (52) of the gas turbine engine (50). Power plant.

10. A power plant comprising at least one gas turbine engine (50) as described in claim 7, wherein the silencer baffle (20), configured as a heat exchanger, is fluidly interposed between the compressor (111) and the combustor (52) of the gas turbine engine (50) through its inlet and outlet ports (23, 24), and the silencer baffle (20), configured as a heat exchanger, is configured to receive at least a portion of the fluid flow transported from the compressor (111) to the combustor (52).

11. The power plant according to claim 10, wherein the compressor (111) is an auxiliary compressor different from the compressor (51) of the gas turbine engine (50), and the compressor (111) is motor-driven.

12. A power plant comprising at least one gas turbine engine (50) as described in claim 7, wherein the gas turbine engine (50) comprises an intake preheating circuit, the intake preheating circuit comprises an intake preheating heat exchanger (56) located upstream of the compressor (51) of the gas turbine engine (50), and the silencer baffle (20), configured as a heat exchanger, is incorporated into the intake preheating circuit through its inlet and outlet ports (23, 24), thereby causing the fluid contained in the intake preheating circuit to flow through the internal cavity (22) for heat exchange fluid located inside the silencer baffle (20), configured as a heat exchanger.

13. A power plant comprising at least one gas turbine engine (50) as described in claim 7, wherein the gas turbine engine (50) comprises a fuel preheating circuit, the fuel preheating circuit comprises a fuel preheating heat exchanger provided upstream of the combustor (52) of the gas turbine engine (50) in a fuel flow path, and the silencer baffle (20), configured as a heat exchanger, is incorporated into the fuel preheating circuit through its inlet and outlet ports (23, 24), thereby causing the fluid contained in the fuel preheating circuit to flow through the internal cavity (22) for heat exchange fluid provided inside the silencer baffle (20), configured as a heat exchanger.

14. The present invention comprises at least one gas turbine engine (50) as described in claim 7, wherein the compressor (51) of the gas turbine engine (50) has an extraction port downstream of the compressor inlet and upstream of the compressor outlet, a first line extending from the extraction port to the low-pressure inlet port of an external compressor (111), thereby fluidly connecting the extraction port to the low-pressure inlet port of the external compressor (111), and a second line connected to the high-pressure outlet port of the external compressor (111) and a heat exchanger. A power plant in which the inlet port (23) of the silencer baffle (20) configured as a heat exchanger is fluidly connected, and a third line is connected to at least one of the high-pressure outlet of the compressor (51) of the gas turbine engine (50) and the combustor (52) of the gas turbine engine (50), and the outlet port (24) of the silencer baffle (20) configured as a heat exchanger is fluidly connected to at least one of the high-pressure outlet of the compressor (51) of the gas turbine engine (50) and the combustor (52) of the gas turbine engine (50).

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