EP2341287A1

EP2341287A1 - Method for maintenance of a combustion chamber of a gas turbine plant and assembling frame for a tile of a combustion chamber

Info

Publication number: EP2341287A1
Application number: EP10197445A
Authority: EP
Inventors: Domenico Iasparro; Matteo Lagostena; Maximiliano Oliva
Original assignee: Ansaldo Energia SpA
Current assignee: Ansaldo Energia SpA
Priority date: 2009-12-30
Filing date: 2010-12-30
Publication date: 2011-07-06
Anticipated expiration: 2030-12-30
Also published as: EP2341287B1; ITMI20092346A1; IT1397226B1

Abstract

A method for the maintenance of a combustion chamber (1), which is provided with a casing (2) and a plurality of first tiles (4) made of refractory material fixed to the casing (2) by means of coupling elements (9), which engage respective lateral faces (6) of the first tiles (4), includes:
- removing coupling elements (9);
- fixing to the casing (2) an assembling frame (21) provided with a central connection element (31);
- centrally fixing a second tile (4a) to the central connection element (31) of the assembling frame (21).

Description

The present invention relates to a method for the maintenance of a combustion chamber of a gas turbine plant for the production of energy and to an assembling frame for a tile of a combustion chamber.
As known, the maintenance of gas turbine plants includes the periodic inspection, repair and replacement, where necessary, of the thermo-insulating coatings of the combustion chambers. The integrity of the thermo-insulating coatings is of fundamental importance since, as known, extremely high temperatures, over 1000°C, are generated inside the combustion chambers. Imperfect thermal insulation could obviously prove to be dangerous for the machine and for the safety of operators inside the plant.
The thermo-insulating coatings normally consist of quadrangular tiles made of refractory material, of several decimetres per side. The tiles are removably mounted in rows by coupling elements to the casing of the combustion chamber. The tiles are mounted in close contact with one another, so as to define a substantially continuous wall which ensures an efficient thermal insulation.
After several cycles of operation, one or more of the tiles may detach from the casing and the casing portions beneath the detached tiles may be subject to damages due to overheating. Normally, the damage also affects the tile coupling elements, which are to be replaced.
However, the overheating damages to the casing often make the replacement of the coupling elements impossible, as well as the replacement of the detached tile.
In these cases, the optimal restoration of the damaged casing areas and assembling of the missing tiles is normally performed. For the restoration of the combustion chamber casing, disassembling the casing and transporting the same to a suitably-equipped maintenance workshop is generally required.
Moreover, disassembling the casing also entails performing the long and laborious operation of taking off the rotor.
In essence, in order to repair the combustion chamber casing, the plant manager is forced to keep the plant idle for a substantially long period, a minimum of 20-30 days, with evident disadvantages from an economic point of view.
It is an object of the present invention to provide a method for the maintenance of a combustion chamber which is free from the prior art drawbacks described herein; in particular, it is an object of the invention to provide a simple, quick method of maintenance which allows the operation of the combustion chamber to be restored in the shortest possible time.
In accordance with these objects, the present invention relates to a method for the maintenance of a combustion chamber of a gas turbine plant; the combustion chamber comprising a casing and a plurality of first tiles of refractory material fixed to the casing by coupling elements, which engage respective lateral faces of the first tiles;
the method comprising the steps of:

removing coupling elements;
fixing to the casing an assembling frame provided with a central connection element;
centrally fixing a second tile to the central connection element of the assembling frame.

It is a further object of the invention to provide an assembling frame for a tile of a combustion chamber which is quick and simple to be used.
In accordance with these objects, the present invention relates to an assembling frame for a tile of a combustion chamber of a gas turbine plant; the assembling frame being provided with at least one through hole for fixing the assembling frame to the casing and with a central connection element for fixing a tile to the assembling frame.
Further features and advantages of the present invention will become apparent from the following description of a non-limiting, exemplary embodiment thereof, with reference to the accompanying drawings, in which:

figure 1 is a diagrammatic view, with parts in section and parts removed for clarity, of a combustion chamber of a gas turbine plant for the production of energy;
figure 2 is a perspective diagrammatic view, with parts removed for clarity, of a detail of the combustion chamber in figure 1;
figure 3 is a top plan view, with parts removed for clarity, of a second detail of the combustion chamber in figure 1 during a first step of the method for the maintenance of the combustion chamber according to the present invention;
figure 4 is a top plan view, with parts removed for clarity, of the detail in figure 3 during a second step of the method for the maintenance of the combustion chamber;
figure 5 is a top plan view, with parts removed for clarity, of the detail in figure 3 during a third step of the method for the maintenance of the combustion chamber.

Figure 1 shows a combustion chamber 1 provided with a casing 2, which defines an area intended for combustion reaction.
Preferably, combustion chamber 1 is of annular type.
Casing 2 has a substantially annular shape and is provided with an internal coating 3, defined by a plurality of tiles 4 made of refractory material arranged in adjacent columns.
With reference to figure 2, tiles 4 have a quadrangular shape and grooves 5 on opposite lateral faces 6. The opposite lateral faces 6 are adjacent to a face 7 facing the interior of combustion chamber 1.
Tiles 4 are fixed to an internal face 8 (seen in figure 3) of casing 2 by coupling elements 9. In the non-limiting example described and illustrated herein, each tile 4 is fixed to the internal face 8 of casing 2 by means of four coupling elements 9.
Each coupling element 9 is fixed to the internal face 8 of casing 2 and is provided with a main body 10a.
Main body 10a is substantially a bar provided, at a first end, with a fixing hole 10b to the internal face 8 and, at a second end, with a fin 10c which engages, in use, the respective groove 5 of the respective tile 4.
When an overheating damage occurs to casing 2, upon the detachment of one of tiles 4, combustion chamber 1 is repaired in accordance with the method of maintenance according to the present invention.
The method for the maintenance of combustion chamber 1 substantially includes removing the coupling elements 9 of the detached tile and eliminating any fused and crystallized material present on area 11 of the internal face 8 beneath the detached tile, e.g. by means of a grinding operation.
With reference to figure 3, once these operations have been carried out, area 11 of the internal face 8 has two longitudinal grooves 12, which were originally intended to accommodate the coupling elements 9.
The method then includes making a coupling hole 13 along each groove 12, preferably in a substantially central position in the groove 12 itself, and making a plurality of cooling holes 15. The cooling holes 15 are in direct communication with a cooling channel (not shown in the accompanying figures for simplicity) along which a cooling fluid flows, preferably air from the compressor. The cooling holes 15 are arranged so as to evenly distribute the cooling fluid along the area 11 of the internal face 8 in order to optimize the cooling of the substitute tile 4a.
Moreover, the method includes making a central cooling hole 17, substantially arranged at the centre of the area 11 and connected to the cooling channel (not shown in the accompanying figures for simplicity).
The method then includes making holes 18 at the ends of the two longitudinal grooves 12 and fixing four flow guiding elements 19 to holes 18, which are adapted to guide the flow of the cooling fluid thus avoiding the leakage thereof at the ends of grooves 12.
Next to each coupling hole 13 is a hole 20, which is the hole originally used for fixing the coupling elements 9.
With reference to figure 4, once these operations have been carried out, the method includes fixing an assembling frame 21 to casing 2.
The assembling frame 21 comprises an external edge 22 having a quadrangular shape substantially identical to that of the detached tile 4, and a central body 23, which is fixed to the external edge 22 and has a substantially rhomboidal shape. The central body 23 is preferably welded to the external edge 22.
The external edge 22 has two appendixes 25, each of which is provided with a through hole 26.
The assembling frame 21 is fixed by screwing two connecting screws 27 into the respective through holes 26 of the external edge 22 and into the respective coupling holes 13 (not seen in figure 4).
The external edge 22 is further provided, at the four vertices thereof, with recirculation channels 28 for the cooling fluid.
Moreover, the external edge 22 has four through holes 29 for accommodating respective spacers 30, adapted to keep a predetermined distance between the substitute tile 4a and the adjacent tiles 4.
The central body 23 of the assembling frame 21 is further provided with a main hole 31, arranged in a central position, and with a plurality of cooling passages 32, which allow the flowing of the cooling fluid to cool the substitute tile 4a.
With reference to figure 5, at this point, the method includes centrally fixing the substitute tile 4a to the assembling frame 21.
The substitute tile 4a is provided with a central through hole 33.
According to a preferred embodiment, the substitute tile 4a is made of metal material, preferably of nickel alloy, and is coated with refractory material, preferably with ceramic material.
The step of centrally fixing the substitute tile 4a to the assembling frame 21 substantially includes arranging an elastic element (not shown for simplicity) about the main hole 31 of the assembling frame 21, and screwing a central blocking screw 34 to central through hole 33 and to main hole 31.
In the non-limiting example described and illustrated herein, the elastic element is provided with a threaded part, which is screwed, in use, to the main hole 31 of the assembling frame 21.
Preferably, the elastic element is a pack of Belleville washers, pre-assembled in the workshop.
Central cooling hole 17 provides for cooling the central blocking screw 34.
In the non-limiting example described and illustrated herein, the central blocking screw 34 has a length such as to partially engage, in use, the cooling hole 17 as well.
Therefore, the dimensioning of the central cooling hole 17 depends on the size of the central blocking screw 34 (the central cooling hole 17 should necessarily have a greater diameter than the central blocking screw 34) and on the temperatures to which the central blocking screw 34 is subjected.
In the non-limiting example described and illustrated herein, the central cooling hole 17 has a diameter of about 17 mm.
The method of maintenance according to the present invention advantageously includes restoring the thermo-insulating coating of casing 2 of combustion chamber 4 in the shortest possible time.
If the overheating damage of the area 11 of casing 2 beneath the detached tile 4 is not particularly serious, the method according to the present invention allows the coating to be quickly restored by applying the substitute tile 4a.
Indeed, the method includes centrally fixing a substitute tile 4a to an assembling frame 21 which in turn is fixed to casing 2.
The overheating damage to the area 11 does not often allow the coupling elements 9 normally used for fixing the refractory tiles 4 to be reapplied.
Moreover, centrally fixing the substitute tile 4a directly to casing 2 may not occur due to various reasons. Firstly, the hole which is to be made in casing 2 should be of sufficient dimensions to accommodate the threaded part of the washer pack and the central blocking screw 34 of the substitute tile 4a. In the example described and illustrated herein, such a hole should have a minimum dimension of about 52 mm. Obtaining a hole of such dimensions on a surface already damaged by overheating is hazardous, as it could cause the wall of casing 2 to collapse. Moreover, obtaining a hole of such dimensions would cause a high production of shavings which would dirty the interior of combustion chamber 4.
Therefore, the method described herein allows a substitute tile 4a to be fixed in a simple, quick and safe manner, thus minimizing the standstill times of the energy production plant.
Finally, it is apparent that modifications and variations may be made to the method for the maintenance of the combustion chamber and to the assembling frame described herein, without departing from the scope of the appended claims.

Claims

Method for the maintenance of a combustion chamber (1) of a gas turbine plant; the combustion chamber (1) comprising a casing (2) and a plurality of first tiles (4) of refractory material fixed to the casing (2) by coupling elements (9), which engage respective lateral faces (6) of the first tiles (4);
the method comprising the steps of:
- removing coupling elements (9);

- fixing to the casing (2) an assembling frame (21) provided with a central connection element (31);

- centrally fixing a second tile (4a) to the central connection element (31) of the assembling frame (21).
Method according to claim 1, wherein the step of fixing to the casing (2) an assembling frame (21) comprises the step of making on the casing (2) a plurality of cooling holes (15) for the flowing of a cooling fluid.
Method according to claim 2, wherein the casing (2) is provided with at least one groove (12); the step of fixing to the casing (2) an assembling frame (21) comprising the step of fixing to the casing (2) at least one cooling fluid guiding element (19) at the ends of the groove (12).
Method according to anyone of the claims from 1 to 3, wherein the step of fixing to the casing (2) an assembling frame (21) comprises the step of making on the casing (2) at least one coupling hole (13) for fixing the assembling frame (21) to the casing (2).
Method according to claim 4, wherein the assembling frame (21) is provided with at least one through hole (26); the step of fixing to the casing (2) an assembling frame (21) comprising the step of screwing at least one connecting screw (27) to the through hole (26) and to the coupling hole (13) of the casing (2).
Method according to claim 5, wherein the second tile (4a) comprises a central through hole (33); the step of centrally fixing the second tile (4a) to the central connecting element (31) of the assembling frame (21) comprises the step of screwing a central blocking screw (34) to the central through hole (33) and to the central connecting element (31) of the assembling frame (21).
Method according to claim 6, wherein the central connecting element (31) of the assembling frame (21) is a hole.
Method according to anyone of the foregoing claims, wherein the second tile (4a) is made of metal material coated with refractory material.
Assembling frame (21) for a tile of a combustion chamber (1) of a gas turbine plant; the assembling frame (21) being provided with at least one through hole (26) for fixing the assembling frame (21) to the casing (2) and with a central connecting element (31) for fixing a tile to the assembling frame (21).
Assembling frame according to claim 9, comprising an external edge (22) and a central body (23); the central body (23) being provided with the central connecting element (31).
Assembling frame according to claim 9 or 10, wherein the central connecting element (31) is a hole.
Assembling frame according to claim 10 or 11, wherein the central body (23) is provided with cooling passages (32) for the flowing of a cooling fluid.