This application claims priority under 35 U.S.C. ยง119 to European application no. No. 10152618.4, filed 4 Feb. 2010, the entirety of which is incorporated by reference herein.
1. Field of Endeavor
The present invention relates to a combustion device of a gas turbine.
2. Brief Description of the Related Art
With reference to
Typically, a zone of the annular combustion chamber 3 downstream of the burners 2 is delimited by a front plate 5; the casings of the burners 2 are connected to this front plate 5.
With reference to
The front sheet 8 and the impingement sheet 7 have aligned holes 11, 12 into which the burners 2 are housed, to project (only for few millimeters) into the combustion chamber 3.
For this reason, in order to seal the combustion chamber 3, between the front sheet 8 and impingement sheet 7, and encircling each of the holes 11, 12, a piston ring 15 is provided.
In fact, since the combustion device 1 is housed within a plenum 6 into which compressed air (from the compressor) is supplied, sealing of the combustion chamber is needed to avoid that an amount of air different from the design amount takes part in the combustion, affecting, inter alia, the flame stability and the NOx emissions.
During operation, the borders of the holes 11 and 12 and the piston ring 15 proved to withstand large damages, due to fretting and wearing.
Damages of those elements may be detrimental to correct operation of the gas turbine, since air in excess of the design amount could enter the combustion chamber, causing the aforementioned drawbacks, such as a reduction of the flame stability and an increase in the NOx emissions.
One of numerous aspects of the present invention includes a combustion device by which the aforementioned problems of the known art are addressed.
Another aspect of the invention includes a combustion device having a front plate with front sheets and impingement sheets provided with holes, for housing the burner casings, and piston rings that, during operation, incur reduced damage when compared to existing traditional combustion devices, in particular due to fretting and wearing.
Another aspect of the invention includes a combustion device that allows operation with increased flame stability and reduced emissions (in particular NOx emissions).
Advantageously, a combustion device in embodiments of the invention and its components has an increased lifetime.
Further characteristics and advantages of the invention will be more apparent from the description of a preferred but non-exclusive embodiment of the combustion device, illustrated by way of non-limiting example in the accompanying drawings, in which:
With reference to the figures, a combustion device 1 is illustrated; the combustion device 1 has the features already described and, thus, it includes a plurality of burners 2 connected to a front plate 5 of a combustion chamber 3; those components are housed in a plenum 6 into which compressed air (from the compressor) in supplied.
The front plate 5 has an annular structure and is preferably made of a plurality of sectors 16 joined together (
Each of these sectors 16 has, spaced apart from one another, a front sheet 8 and an impingement sheet 7 with aligned holes (respectively identified by the reference numbers 11 and 12).
Each couple of holes 11 and 12 houses one burner 2.
In addition, a piston ring 15 is provided between the front sheet 8 and impingement sheet 7 to seal the holes 11, 12, preventing compressed air contained in the plenum 6 from entering into the combustion chamber 3.
Advantageously, the axial length of the borders of the holes 11 and/or 12 (i.e., the length of these borders along an axis 18 perpendicular to the corresponding front or impingement sheet 8, 7) is longer than the thickness of the corresponding front sheet 8 and/or impingement sheet 7.
In order to define a border of the holes 11 and/or 12 longer than the thickness of the corresponding front sheet 8 and/or impingement sheet 7, the front sheet 8 and/or impingement sheet 7 are preferably made in two different pieces, one of them defining the holes 11 and/or 12.
In particular, a first piece 20 defining the holes 11 and/or 12 is welded to a second piece 21 defining the main portion of the front sheet 8 and/or impingement sheet 7.
Preferably, the first piece 20 and the second piece 21 define the front sheet 8; in addition a heat resistant protective layer 9 is provided on the side of the front sheet 8 facing the inner of the combustion chamber 3 covering a welding 24 (advantageously an orbital welding) between the first piece 20 and second piece 21.
Advantageously, the border of the hole 11 has a wear resistant protective coating 25 that extends up to the first piece side 26 facing the piston ring 15. Naturally also the hole 12 may be provided with the protective coating 25 also extending up to the second piece side facing the piston ring.
The first piece 20 and the second piece 21 have cooling through holes.
In this respect, the cooling through holes 28 of the first piece 20 may be realized in a portion having the same thickness of the second piece 21 and/or in a portion having a larger thickness thereof and are preferably inclined with respect to a hole axis 30.
As shown, the through holes 28 of the first piece 20 converge towards the inner of the combustion chamber 3.
The cooling through holes 32 of the second piece 21 are preferably parallel to the axis 18.
Moreover, as shown in the figures, the inner diameter of the piston ring 15 is smaller than the inner diameter of the hole 11 of the front sheet 8 that is smaller than the inner diameter of the hole 12 of the impingement sheet 7.
In the following, particular embodiments will be described in detail; the same references are used through all those embodiments to identify identical or similar elements.
Tests showed that surprisingly, during operation, the borders of the holes 11 and 12 and the piston ring 15 incurred much less damages due to fretting and wearing than in traditional configurations.
This allowed reduced air leakage from the plenum 6 into the combustion chamber 3, such that better combustion conditions and lifetime increase are achieved.
Naturally the features described may be independently provided from one another.
In practice the materials used and the dimensions can be chosen at will according to requirements and to the state of the art.
While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.
Number | Date | Country | Kind |
---|---|---|---|
10152618 | Feb 2010 | EP | regional |
Number | Name | Date | Kind |
---|---|---|---|
5273249 | Peterson et al. | Dec 1993 | A |
5509270 | Pearce et al. | Apr 1996 | A |
7690207 | Markarian et al. | Apr 2010 | B2 |
7770397 | Patel et al. | Aug 2010 | B2 |
20080092546 | Stastny et al. | Apr 2008 | A1 |
20080236169 | Hawie et al. | Oct 2008 | A1 |
20080264444 | Minor et al. | Oct 2008 | A1 |
20080282703 | Morenko et al. | Nov 2008 | A1 |
20110120132 | Rudrapatna et al. | May 2011 | A1 |
Number | Date | Country |
---|---|---|
1271059 | Jan 2003 | EP |
1507121 | Feb 2005 | EP |
1741982 | Jan 2007 | EP |
1767855 | Mar 2007 | EP |
Entry |
---|
European Search Report for EP Patent App. No. 10152618.4 (Aug. 19, 2010). |
Number | Date | Country | |
---|---|---|---|
20110185746 A1 | Aug 2011 | US |