EP3117147B1

EP3117147B1 - Combustion chamber of a gas turbine assembly

Info

Publication number: EP3117147B1
Application number: EP15715825.4A
Authority: EP
Inventors: Antonino LUTRI
Original assignee: Ansaldo Energia SpA
Current assignee: Ansaldo Energia SpA
Priority date: 2014-03-03
Filing date: 2015-03-03
Publication date: 2019-01-16
Anticipated expiration: 2035-03-03
Also published as: CN106164590A; CN106164590B; WO2015132728A1; EP3117147A1

Description

TECHNICAL FIELD

The present invention relates to a combustion chamber of a gas turbine assembly.

BACKGROUND ART

As known, the combustion chambers of gas turbines must be internally lined with heat shields that allow protecting the structure and the members of the machine from very high temperatures. Inside the combustion chamber, in fact, temperatures can exceed 1500-1600 °C and are therefore high enough to melt the surrounding metal structures.
In gas turbines of plants for the production of electricity, heat shields generally include a plurality of contiguous tiles of a refractory material arranged in arrays or rows along respective circumferences, so as to form a surface as much as possible continuous.
The tiles are fixed to a casing of the combustion chamber by respective metal supporting elements. For most of the tiles, the supporting elements are defined by pairs of elastic guides which extend longitudinally with respect to the casing and act in contrast with the sidewalls of the tiles. The latter are shaped so as to be contiguous to the sidewalls of adjacent tiles and also protect the respective supporting elements from the effects of combustion. The elastic guides are normally fixed permanently to the wall and the tiles are slidably inserted along the wall of the combustion chamber casing in the longitudinal direction.
At least one row of tiles, however, must be fixed by removable supporting elements to be tightened after the placement of the tiles themselves. For this reason, part of the removable supporting elements remains necessarily exposed to high temperatures.
Combustion chambers are normally provided with cooling systems which, through the circulation of a stream of relatively cool air, allow limiting the temperatures of the tile supports and the damage that might result therefrom.
Despite any precautions, however, the exposed portions of the supporting elements tend to deteriorate and may undergo irreversible and potentially catastrophic damage. In particular, extensive burns and cracks may occur which impair the functionality of the supports. In some cases, the detachment of metal portions may occur, which may be conveyed towards the turbine by the flow of flue gas and cause the destruction of several blades.
On the one hand, therefore, the operational safety of the combustion chamber is reduced over time. With use, in fact, the risk of mechanical failures that impair the efficacy of the heat shield against the parts that should be protected increases, and may cause serious structural damage.
On the other hand, also the simple loss of efficacy of the heat shield forces to relatively frequent maintenance operations in which damaged elements need to be replaced. The plant management costs are thus high, especially in view of the long periods of downtime necessary for carrying out the operations. These, in fact, require disassembly of important parts of the machine, the inspection and replacement of damaged components and the subsequent reassemble and may prevent the operation of the system even for weeks.
DE 36 25 056 A1 discloses a combustion chamber of a gas turbine assembly, comprising a casing, defining a combustion volume therein; a heat shield, which lines the inside of the casing and comprises a plurality of tiles of a refractory material; and structural elements shaped so as to define housing seats of the tiles and to withhold the tiles in the respective housing seats. The structural elements comprise supporting elements for a group of tiles. The supporting elements have respective protecting plates which delimit a respective portion of the combustion volume. Moreover, each supporting element comprises a base, fixed to the casing, and a pair of elastic fastening elements, extending from the base opposite to each other and shaped so as to withhold portions of respective first tiles against the casing. The protecting plate of each supporting element is carried by at least one respective elastic fastening element and is arranged to cover the base.
Other examples of known supporting elements are disclosed in US 5 113 660 A and in US 5 957 067 A .

DISCLOSURE OF INVENTION

It is therefore an object of the present invention to provide a combustion chamber of a gas turbine assembly.
According to the present invention, a combustion chamber of a gas turbine assembly is provided, as defined in claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings, which show some non-limiting embodiment examples thereof, in which:

figure 1 is a perspective view of a portion of a gas turbine assembly according to an embodiment of the present invention;
figure 2 is a front view of the combustion chamber in figure 1, partially sectional along an axial longitudinal plane;
figure 3 shows an enlarged detail of the view in figure 2, where supporting elements for heat insulating tiles according to an embodiment of the present invention are shown;
figure 4 is a front view of one of the supporting elements in figure 2;
figure 5 is a rear view of the supporting element in figure 4;
figure 6 is a right side view of the supporting element in figure 4;
figure 7 is a bottom plan view of the supporting element in figure 4, sectioned along the track plane VII-VII in figure 4;
figure 8 is a simplified and enlarged perspective view, partially sectioned along an axial longitudinal plane and with parts removed for clarity, of a portion of the combustion chamber in figure 2;
figure 9 is a front view of a combustion chamber of a gas turbine assembly according to a different embodiment of the present invention, partially sectional along an axial longitudinal plane;
figure 10 shows an enlarged detail of the view in figure 9, where supporting elements for heat insulating tiles according to an embodiment of the present invention are shown.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to figure 1, a gas turbine assembly of a plant for the production of electricity, only partially shown, is indicated as a whole with reference numeral 1. The gas turbine assembly 1 comprises a compressor 2, a combustion chamber 3 and a gas turbine 5. A rotor 7 comprises a compressor portion 7a and turbine portion 7b.
The combustion chamber 3, also shown in figure 2, is of the silo type and, in one embodiment, comprises a casing 8 defined by a substantially cylindrical tower which extends about a vertical axis A and defines a combustion volume 8a therein. The combustion volume is superiorly delimited by a roof 8b of the casing 8 and fluidically communicates on an opposite side with the gas turbine 5. The combustion chamber 3 is provided with burners 9 which allow burning a mixture of air coming from compressor 2 and fuel supplied through a supply line (not shown).
The combustion chamber 3 is also internally lined with a heat shield 10, which comprises a plurality of tiles 12 arranged in adjacent rows about axis A.
Tiles 12a of a closing row are fixed to casing 8 by supporting elements 15, described in detail hereafter. Tiles 12 of the other rows may be fixed to casing 8 by conventional supporting elements, not shown herein for convenience. In the embodiment of figure 2, the closing row of tiles 12a is arranged centrally. Tiles 12a of the closing row are the last ones to be mounted after all the other tiles have been placed in their respective positions, normally by sliding them along longitudinal rails (not shown) with respect to casing 8. Conversely, tiles 12a are the first ones to be removed when part or all of the heat shield 10 needs to be removed.
Tiles 12a of the closing row are fixed to the casing 8 each by four respective supporting elements 15, two on each sidewall, as shown in more detail in figure 3.
Figures 4-7 show one of the supporting elements 15, to which reference shall be made, meaning that the others are the same.
The supporting element 15 comprises a base 16, a pair of elastic fastening elements 17 and a protecting plate 18 which, in one embodiment, are made in one piece.
Base 16 is tightened against casing 8 by a fixing plate 19 (figure 3).
The elastic fastening elements 17 extend in opposite directions from base 16 in a substantially symmetrical way and are shaped so as to withhold portions of respective tiles 12a against casing 8, as shown in figure 7 (where casing 8 and tiles 12a are shown with a dashed and dotted line). More precisely, the elastic fastening elements 17 are inclined by angles α substantially symmetrical with respect to base 16 and extend transversely to the sidewalls of the respective tiles 12a. Angles α are comprised between 30° and 60° and, in one embodiment, they are about 46.5°. Ends of the elastic fastening elements 17 opposite to base 16 are arranged in contrast against respective edges of tiles 12a, so as to prevent tiles 12a themselves from separating from casing 8.
As shown in figures 4-7, the protecting plate 18, substantially rectangular in shape, is connected to one of the elastic fastening elements 17 and is arranged to cover base 16. In one embodiment, the protecting plate 18 is substantially parallel to base 16 and extends between tiles 12a supported by the supporting element 15. In practice, the protecting plate 18 closes the gap between tiles 12a, where the supporting element 15 is arranged (figures 3 and 7), and prevents base 16 and the elastic fastening elements 17 from being directly exposed to the atmosphere present in the combustion volume 8a. One side of the protecting plate 18 not engaged against tiles 12a is shaped to accommodate a fastening element 20 (figure 3).
In each supporting element 15, a face 18a of the protecting plate 18 oriented towards the inside of casing 8 is covered with a heat insulating layer 22 of a heat insulating material which acts as a thermal protection element for the protecting plate 18 itself. The heat insulating layer 22 completely covers the protecting plate 18 and slopes down to disappear on a connecting portion 24 of the supporting element 15 between the protecting plate 18 and the elastic fastening element 17 connected thereto.
In one embodiment, the heat insulating material is a refractory material, for example a ceramic material having a porosity value greater than 20%. In a different embodiment, the heat insulating material contains a MCrAlY alloy, where M can be iron, cobalt, nickel or cobalt/nickel.
The heat insulating layer 22 has such a thickness as to prevent potentially harmful temperatures from propagating to the supporting element 15. For example, the thickness of the heat insulating layer 18 is between 75 µm and 175 µm, preferably between 100 µm and 150 µm.
The presence of the heat insulating layer 22 avoiods or at least substantially reduces the risk of damage to the protecting plate 18 as a result of the high temperatures which develop inside the combustion volume 8a. Accordingly, the structural and functional integrity of the heat shield 10 is maintained longer, on one hand preserving the efficiency of the machine and, on the other hand, reducing the need for maintenance operations and the associated costs for downtime. Moreover, the danger of breakage and catastrophic damage is prevented.
With reference to figure 8, an annular ridge 25 axially delimits a seat 26 for housing an upper row of tiles 12b adjacent to a roof 8b of casing 8. The annular ridge 25, which is part of the structure of casing 8, is made of a metal material while roof 8b is lined with a refractory material.
Tiles 12b are arranged in seat 26 and have upper edges 12c protruding towards roof 8b of casing 8, so as to cover respective portions of the annular ridge 25. Edges 12c therefore perform the function of thermal protection elements for the annular ridge 25.
Advantageously, tiles 12b have a first face 12d, adjacent to casing 8, and a second face 12e, oriented towards the combustion volume 8a, inclined with respect to each other. In this way, tiles 12b have a first thickness S1 at edges 12c and a second thickness S2, smaller than the first thickness S1, at second edges 12f, opposite to the first edges 12c. In particular, the first thickness S1 is sufficient to shape tiles 12b so that edges 12c may cover the annular ridge 25. On the other hand, the second thickness at edges 12f is substantially equal to the thickness of the contiguous tiles 12. The surface of the heat shield 10, which delimits the combustion volume 8a, is therefore substantially free from discontinuity, without the need to increase the thickness of the other tiles 12 in order to obtain the protruding edges 12c beyond what is required by the insulation needs.
According to a different embodiment of the invention, shown in figures 9 and 10, a combustion chamber 103 of a gas turbine, of the silo type, comprises a casing 108 which extends about an axis A' and internally delimits a combustion volume 108a.
Casing 108 is internally lined with a heat shield 110, which comprises a plurality of tiles 112 arranged in adjacent rows about axis A'.
In this case, the heat shield 110 has two closing rows, more precisely comprising tiles 112a adjacent to a roof 108b of casing 108 and tiles 112b contiguous to tiles 112a.
Tiles 112a, 112b are fixed to casing 108 by means of supporting elements 15, of the type already described with reference to figure 4-7. Each tile 112a, 112b has a pair of supporting elements 15 on each sidewall.
Finally, it is clear that changes and variations may be made to the combustion chamber described without departing from the scope of the present invention, as defined in the appended claims.

Claims

A combustion chamber of a gas turbine assembly, comprising:
a casing (8; 108), defining a combustion volume (8a; 108a) therein;

a heat shield (10; 110), which lines the inside of the casing (8; 108) and comprises a plurality of tiles (12, 12a, 12b; 112, 112a, 112b) of a refractory material;

structural elements (15; 25) shaped so as to define housing seats (26) of the tiles (12, 12a, 12b; 112, 112a, 112b) and withhold the tiles (12, 12a, 12b; 112, 112a, 112b) in the respective housing seats (26);

wherein the structural elements (15; 25) comprise supporting elements (15) for a group of first tiles (12a; 112a, 112b), each having a protecting plate (18) which delimits a respective portion of the combustion volume (8a; 108a) ;

wherein each supporting element (15) comprises a base (16), fixed to the casing (8; 108), and a pair of elastic fastening elements (17), extending from the base (16) opposite to each other and shaped so as to withhold portions of respective first tiles (12a; 112a, 112b) against the casing (8; 108); wherein the protecting plate (18) of each supporting element (15) is carried by at least one respective elastic fastening element (17) and is arranged to cover the base (16);

characterized by thermal protection elements (22), arranged so as to cover portions of the structural elements (15; 25) facing the inside of the casing (8; 108); wherein the thermal protection elements comprise heat insulating layers (22) of heat insulating material, lining respective faces (18a) of respective protecting plates (18) oriented towards the inside of the casing (8; 108).
A combustion chamber according to claim 1, wherein the heat insulating material is a refractory material.
A combustion chamber according to claim 1 or 2, wherein the heat insulating material is a ceramic material with a porosity value higher than 20%.
A combustion chamber according to claim 1 or 2, wherein the heat insulating material contains a MCrAlY alloy.
A combustion chamber according to any one of the preceding claims, wherein a thickness of the heat insulating layers (22) is between 75 µm and 175 µm, preferably between 100 µm and 150 µm.
A combustion chamber according to any one of the preceding claims, wherein the protecting plate (18) is essentially parallel to the respective base (16) in each supporting element (15).
A combustion chamber according to any one of the preceding claims, wherein the heat insulating layers (22) are arranged on faces (18a) of the protecting plates (18) opposite to the respective bases (16).
A combustion chamber according to any one of the preceding claims, wherein the protecting plates (18) extend between the first tiles (12a; 112a, 112b) supported by the respective supporting elements (15).
A combustion chamber according to any one of the preceding claims, wherein the structural elements (15; 25) comprise an annular ridge (25), axially delimiting the housing seat (26) of a group of second tiles (12b) adjacent to a roof (8b) of the casing (8); and wherein the thermal protection elements comprise first edges (12c) of the second tiles (12b), protruding so as to cover respective portions of the annular ridge (25).
A combustion chamber according to claim 9, wherein the second tiles (12b) have a first thickness (S1) at the first edges (12c) and a second thickness (S2), smaller than the first thickness (S1), at the second edges (12f), opposite to the first edges (12c).
A combustion chamber according to claim 10, wherein the thickness of third tiles (12) adjacent to the second tiles (12b) is equal to the second thickness (S2).
A combustion chamber according to claim 10 or 11, wherein each second tile (12) has a first face (12d) and a second face (12e) inclined with respect to the first face (12d) in a direction from the first edge (12c) to the second edge (12f).