Gas turbine assembly

Abstract

A gas turbine assembly comprising: a compressor (3) configured to compress air; the compressor (3) extending along a longitudinal axis and provided with an outlet diffuser (26) and a compressor casing (9a); a plenum (30) being a closed volume delimited at least by an outer shell (31) coupled to the compressor casing (9a) and the outlet diffuser (26); the outlet diffuser (26) being designed to discharge the compressed air into the plenum (30); a combustor (4) arranged partially in the plenum (30); at least one pressure sensor (7; 7a; 7b; 7c) facing an area of the plenum (30) comprised between the outer shell (31) and the outlet diffuser (26).

Description

[0001] Cross Reference to Related Applications

[0002] This patent application claims priority from European patent application no. 19425103.9, filed on December 31, 2019, the entire disclosure of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present invention relates to a gas turbine assembly.

[0004] In particular, the gas turbine assembly of the present invention is part of a power plant for the production of electric energy. BACKGROUND

[0005] As known, a gas turbine assembly for a power plant comprises a compressor, a combustor and a turbine.

[0006] In particular, the compressor comprises an inlet supplied with air and a plurality of rotating vanes through which the air is compressed. The compressed air exiting the compressor flows into a plenum, i.e. a closed volume delimited by a casing, and from there enters the combustor. Inside the combustor, the compressed air is mixed with at least one fuel and combusted. The hot gases produced exit the combustor and expand in the turbine. In the turbine, the expansion of the hot gases causes the rotating vanes, connected to a rotor, to move, thus doing work.

[0007] In recent years, under the pressure of increasingly stringent regulations regarding the emission of polluting substances, combustion technology has shifted towards the use of so-called "lean premix" technology, which provides for the use of combustors in which the fuel is premixed with air before combustion.

[0008] In this type of combustor, in which a lean fuel mixture is burned, at high power, it is possible that acoustic oscillations are spontaneously triggered (here and in the following identified with the term "rumble" typically used in the reference sector), which are destructive to the structural integrity of the combustor.

[0009] Therefore, monitoring the acoustic pressure oscillations in the combustor is fundamental for the reliable and efficient operation of the gas turbine assembly.

[0010] However, the acoustic pressure oscillations should be monitored in a reliable manner, since the risks associated with non-optimal monitoring are very serious: reduction in power output and loss of combustor component integrity.

[0011] However, the current solutions are not able to detect the pressure fluctuations in a reliable manner. In particular, for correct engine operation, especially for certain frequency bandwidths of interest, the known solutions do not exhibit complete sensitivity to the dynamic phenomena of interest. SUMMARY

[0012] It is therefore an object of the present application to provide a gas turbine assembly which is able to avoid or at least mitigate the described drawbacks.

[0013] In particular, it is an object of the present application to provide a gas turbine assembly configured to allow a reliable detection of pressure fluctuations.

[0014] According to the present application, there is provided a gas turbine assembly comprising:

[0015] • a compressor configured to compress air; the compressor extending along a longitudinal axis and being provided with an outlet diffuser and a compressor casing;

[0016] • a plenum which is a closed volume delimited at least by an outer shell coupled to the compressor casing and by the outlet diffuser; the outlet diffuser being designed to discharge the compressed air into the plenum;

[0017] • a combustor arranged partially in the plenum;

[0018] • at least one pressure sensor facing an area of the plenum comprised between the outer shell and the outlet diffuser.

[0019] Thanks to the arrangement of the pressure sensor according to the present application, an enhanced monitoring of the pressure amplitude is achieved with a significant improvement of the engine tuning and operation without affecting the overall engine efficiency in terms of air consumption or operating conditions variations. In particular, thanks to the position of the pressure sensor according to the present application, a better sensitivity is achieved for all the bandwidth of frequencies of interest.

[0020] Advantageously, the present application can be applied to existing gas turbine assemblies. BRIEF DESCRIPTION OF DRAWINGS

[0021] The present application will now be described with reference to the accompanying drawings, which show some non-limiting embodiments, in which:

[0022] - Figure 1 is a schematic cross-sectional view of a gas turbine assembly according to the present application (with some components removed);

[0023] - Figure 2 is an enlarged view of a detail of the gas turbine assembly of Figure 1 ;

[0024] - Figure 3 is a schematic cross-sectional view of further details of the gas turbine assembly of Figure 1 ;

[0025] - Figure 4 is a schematic cross-sectional view of further details of the gas turbine assembly of Figure 2 according to an alternative embodiment (with some components removed). DETAILED DESCRIPTION

[0026] In Figure 1 , reference 1 refers to a gas turbine assembly (schematically shown in Figure 1 ).

[0027] The gas turbine assembly 1 comprises a compressor 3, a combustor 4, a gas turbine 5, at least one pressure sensor 7 and a control device (not shown in the figures).

[0028] The compressor 3 and the turbine 5 are mounted on the same shaft to form a rotor 8 extending along an axis A.

[0029] The rotor 8 is coupled to an electric generator (not shown in the figures for simplicity).

[0030] In more detail, the rotor 8 comprises a front shaft 10, a plurality of rotor assemblies 11 and a rear shaft 13.

[0031] Each rotor assembly 11 comprises a rotor disc 15 and a plurality of rotor blades 16 coupled to the rotor disc 15 and arranged radially.

[0032] The plurality of rotor discs 15 is arranged in succession between the front shaft 10 and the rear shaft 13 and is clamped in a set, preferably by means of a central tie rod 14. As an alternative, the rotor discs can be welded together.

[0033] A central shaft 17 separates the rotor discs 15 of the compressor 3 from the rotor discs 15 of the turbine 5 and extends through the combustor 4.

[0034] Furthermore, stator assemblies 22 alternate with the compressor rotor assemblies 11.

[0035] Each stator assembly 22 comprises a stator ring 24 and a plurality of stator vanes 25 arranged radially and coupled to the stator ring 24.

[0036] In particular, the stator vanes 25 in the compressor 3 are coupled to the stator ring 24 and to a compressor stator casing 9a, while the stator vanes 25 in the turbine 5 are coupled to the stator ring 24 and to a turbine stator casing 9b.

[0037] The compressor 3 is also provided with an outlet diffuser 26 arranged at the outlet of the compressor 3.

[0038] The diffuser 26 is designed to discharge the compressed air into a plenum 30.

[0039] With reference to Figure 2 , the diffuser 26 comprises two casings 27a, 27b which define a channel with an ever-increasing section in order to reduce the speed of the air flow travelling. The casings 27a, 27b couple the compressor stator casing 9a.

[0040] Preferably, the casing 27a facing the plenum 30 is provided with a substantially cylindrical first portion 28a and a substantially truncated-cone-shaped second portion 28b folded on the first portion 28a. The first portion 28a defines an outer face 29a, while the second portion substantially defines an outer face 29b.

[0041] The plenum 30 is a closed volume delimited at least by the outer shell 31 and by the outlet diffuser 26, in which the compressed air coming from the outlet diffuser 26 is collected.

[0042] The plenum 30 is also delimited by other components of the gas turbine assembly 1, such as the gas turbine casing 9b.

[0043] At least a portion of the combustor 4 is arranged in the plenum 30.

[0044] The outer shell 31 is coupled to the compressor stator casing 9a.

[0045] Preferably, the outer shell 31 has at least one truncated-cone-shaped portion 32.

[0046] Preferably, the portion 32 is provided with a plurality of holes 33 housing the fuel supply pipes 35 of the combustor 4.

[0047] Preferably, the radius of the portion 32 increases towards the turbine 5.

[0048] Preferably, the outer shell 31 is fixed to the first portion 38 of the compressor stator casing 9a by means of bolts 39.

[0049] Preferably, a partition 40 is arranged between the second portion 42 of the compressor stator casing 9a and the outer shell 31.

[0050] Preferably, the partition 40 is arranged on a plane substantially perpendicular to the longitudinal axis A.

[0051] More preferably, the partition 40 is arranged at substantially the same axial position as the last stator stage 22 of the compressor 3.

[0052] The partition 40 is preferably substantially coupled to the end of the portion 32 having the smallest radius.

[0053] Preferably, the second portion 42 of the compressor stator casing 9a is configured to support at least the last stator stage 22 of the compressor 3.

[0054] In the non-limiting example disclosed and shown here, the second portion 42 of the compressor stator casing 9a is configured to support the last seven stator stages 22 of the compressor 3.

[0055] The diffuser 26 is coupled to the second portion 42 of the compressor stator casing 9a.

[0056] Preferably, the outer shell 31 is also coupled to the turbine stator casing 9b.

[0057] In use, air is supplied to the compressor 3. In the compressor 3, the rotation of the compressor rotor assembly 11, alternating with the stator assembly 22, compresses the air passing through.

[0058] The compressed air leaving the compressor 3 flows into the plenum 30 through the diffuser 26. The compressed air flows from the plenum 30 into the combustor 4. Inside the combustor 4, the compressed air is mixed with at least one fuel and combusted. The hot gases produced leave the combustor 4 and expand in the turbine 5.

[0059] In the compressor 3 and in the turbine 5, the flow proceeds in the forward direction D.

[0060] With reference to Figure 2 The gas turbine assembly 1 comprises at least one pressure sensor 7 facing a region of the plenum 30 comprised between the diffuser 26 and the portion 32 of the casing 31.

[0061] Preferably, the gas turbine assembly 1 comprises at least one pressure sensor 7 facing a region of the plenum 30 comprised between the diffuser 26 and the portion 32 of the casing 31.

[0062] Preferably, the gas turbine assembly 1 comprises at least one pressure sensor 7a arranged in the plenum 30 between the diffuser 26 and the portion 32 of the casing 31 closer to the diffuser 26 than to the casing 31.

[0063] Preferably, the gas turbine assembly 1 comprises at least one pressure sensor 7a arranged closer to the diffuser 26 between the diffuser 26 and the portion 32 of the casing 31.

[0064] More preferably, the pressure sensor 7a faces a region comprised between the outer face 29a and the outer face 29b.

[0065] In the non-limiting example disclosed and shown here, the pressure sensor 7a is arranged close to the coupling region between the casing 27a and the compressor stator casing 9a.

[0066] Preferably, the pressure sensor 7a is coupled to the portion of the casing 27a coupled to the compressor stator casing 9a.

[0067] In the non-limiting example disclosed and shown here, a plurality of pressure sensors 7a are arranged along a circumference extending around the longitudinal axis A. In other words, the pressure sensors 7a are arranged in different sectors of the plenum 30.

[0068] Preferably, the gas turbine assembly 1 comprises at least one pressure sensor 7b arranged in a pressure tapping interface 43 made in the casing 31.

[0069] In the non-limiting example disclosed and illustrated here, the pressure measurement interface 43 is defined by a tube 45 housed in a hole 46 of the casing 31.

[0070] Preferably, the hole 46 is made in the portion 32 of the casing 31.

[0071] According to a variant not illustrated, the sensor can be arranged between the diffuser 26 and the portion 32 of the casing 31 closer to the casing 31 than to the diffuser 26.

[0072] In the non-limiting example disclosed and illustrated here, the plurality of pressure sensors 7b is arranged along a circumference extending around the longitudinal axis A. In other words, the pressure sensors 7b are arranged in different sectors of the plenum 30.

[0073] According to an embodiment not illustrated, the gas turbine assembly comprises only one sensor between the sensor 7a and the sensor 7b.

[0074] The sensor data detected by the sensor 7a and / or by the sensor 7b are sent to the control device.

[0075] Figure 4 An alternative embodiment according to the application is illustrated, in which the sensor 7b is replaced by a sensor 7c arranged at an end 48 of a pipe 47 extending from the casing 31 into the plenum 30. The pipe 47 is oriented so that the end 48 is arranged closer to the diffuser 26 than to the casing 31.

[0076] In the non-limiting example disclosed and illustrated here, the pipe 47 is housed in a hole 49 of the casing 31.

[0077] Preferably, the hole 49 is made in the portion 32 of the casing 31.

[0078] In the non-limiting example disclosed and illustrated here, the plurality of pressure sensors 7c is arranged along a circumference extending around the longitudinal axis A. In other words, the pressure sensors 7c are arranged in different sectors of the plenum 30.

[0079] The sensor data detected by the sensor 7a and / or by the sensor 7c are sent to the control device.

[0080] According to an embodiment not illustrated, the gas turbine assembly comprises only one sensor between the sensor 7a and the sensor 7c.

[0081] According to an embodiment not illustrated, the gas turbine assembly comprises all the sensors 7a, 7b and 7c.

[0082] Preferably, the total number of pressure sensors 7a and / or 7b and / or 7c to be installed in the combustor 4 is mainly related to the acoustic modes that must be monitored.

[0083] The final position of the sensors 7a and / or 7b and / or 7c depends on the acoustic mode to be monitored, also taking into account the necessity of thermal structural behavior and / or avoiding any interference with existing components.

[0084] Preferably, the pressure sensors 7a and / or 7b and / or 7c are pressure probes.

[0085] Finally, it is clear that modifications and variants can be made to the method and to the gas turbine assembly described herein, without departing from the scope of the present application as defined in the annexed claims.

Claims

1. A gas turbine assembly, comprising: • Compressor (3), the compressor (3) being configured to compress air; The compressor (3) extends along the longitudinal axis and is provided with an outlet diffuser (26) and a compressor housing (9a); • Air chamber (30), the air chamber (30) being a closed volume defined at least by a housing (31) connected to the compressor housing (9a) and the outlet diffuser (26); the outlet diffuser (26) being designed to discharge compressed air into the air chamber (30); • Burner (4), which is partially arranged in the gas chamber (30); • At least one pressure sensor (7; 7a; 7b; 7c) facing the area of ​​the air chamber (30) between the housing (31) and the outlet diffuser (26).

2. The gas turbine assembly according to claim 1, characterized in that, The housing (31) includes a truncated cone-shaped portion (32); the at least one pressure sensor (7; 7a; 7b; 7c) faces the region of the air chamber (30) between the portion (32) and the outlet diffuser (26).

3. The gas turbine assembly according to claim 1, characterized in that, At least one first sensor (7a) is arranged in the region of the air chamber (30) included between the housing (31) and the outlet diffuser (26) to be closer to the outlet diffuser (26) than to the housing (31).

4. The gas turbine assembly according to claim 3, characterized in that, The outlet diffuser (26) includes at least two housings (27a, 27b) defining a channel with an increasing cross-section, the at least two housings (27a, 27b) being coupled to a compressor stator housing (9a); the housing (27a) facing the gas chamber (30) has a generally cylindrical first portion (28a) and a generally truncated conical second portion (28b) folded over the first portion (28a); the first portion (28a) defines a first outer surface (29a); the second portion defines a second outer surface (29b).

5. The gas turbine assembly according to claim 4, characterized in that, At least one first sensor (7a) is arranged to face the region included between the first outer surface (29a) and the second outer surface (29b).

6. The gas turbine assembly according to any one of claims 3 to 5, characterized in that, The first pressure sensor (7a) is arranged near the connection area between the outlet diffuser (26) and the compressor stator housing (9a).

7. The gas turbine assembly according to any one of claims 3 to 5, characterized in that, It includes a plurality of first pressure sensors (7a) arranged along a circumference extending around the longitudinal axis (A).

8. The gas turbine assembly according to any one of claims 1 to 5, characterized in that, At least one second pressure sensor (7b) is arranged between the diffuser (26) and the housing (31) closer to the housing (31) than to the diffuser (26).

9. The gas turbine assembly according to any one of claims 1 to 5, characterized in that, At least one second pressure sensor (7b) is arranged in a pressure measuring interface (43) manufactured in the housing (31).

10. The gas turbine assembly according to claim 9, characterized in that, The pressure measuring interface (43) is defined by a tube (45) housed in a hole (46) in the housing (31).

11. The gas turbine assembly according to claim 8, characterized in that, It includes a plurality of second pressure sensors (7b) arranged along a circumference extending around the longitudinal axis (A).

12. The gas turbine assembly according to any one of claims 1 to 5, characterized in that, At least one third sensor (7c) is arranged at the end (48) of a pipe (47) extending from the housing (31) into the air chamber (30).

13. The gas turbine assembly according to claim 12, characterized in that, The conduit (47) is oriented such that the end (48) is arranged closer to the outlet diffuser (26) than to the housing (31).

14. The gas turbine assembly according to claim 12, characterized in that, The pipe (47) is accommodated in the hole (49) of the outer casing (31).

15. The gas turbine assembly according to claim 12, characterized in that, It includes a plurality of third pressure sensors (7c) arranged along a circumference extending around the longitudinal axis (A).

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