Patent Application
20120260657
The present disclosure relates to a gas turbine, such as, a gas turbine that includes a combustor.
Known gas turbines can include combustors wherein compressed air coming from the compressor is fed and mixed with a gaseous or liquid fuel that is combusted in the combustor.
Under certain conditions, such as when low emissions are pursued or at part load, for example, pressure oscillations can be generated in the combustor due to thermo acoustic instabilities. These pressure oscillations can cause structural damages or excessive wear of the gas turbine components and, in addition, a noisy operation.
In an effort to guarantee an acceptable gas turbine lifetime and control noise, pressure oscillations during operation of the gas turbine should be damped.
In known implementations damping can be achieved by passive damping structures. Examples of these passive damping structures are Helmholtz resonators, quarter-wave tubes, screen or perforated screech liners. During manufacture, known gas turbines are first designed and optimized without passive damping structures. Passive damping structures can be later added, as necessary, based on desired results of a specified implementation. As a result, in order to provide proper cooling of damping structures, cooling air should be diverted from other gas turbine regions, causing an increase in operating temperature and shortening its operational lifetime.
In addition, as often as air is taken away from the combustor (or in sequential combustion gas turbines from the first combustor) the flame temperature increases thus increasing the NOx emissions.
U.S. Pat. No. 7,104,065 discloses a damping arrangement for a combustor with a two-walled combustion chamber and a further outer wall defining a gastight volume connected to the inner of the combustion chamber. In addition to the drawbacks already described, this damping arrangement is functionally separated from the other components of the combustor and, moreover, it proved difficult to incorporate it in the combustor, due to the limited space available.
An exemplary combustor is disclosed comprising: at least a portion having an inner liner and an outer cover plate which together form an interposed cooling chamber; a plurality of hollow elements extend from said liner and protrude into the cooling chamber, each hollow element defining a damping volume connected to a combustion chamber via a calibrated duct, such that during operation said hollow elements damp pressure pulsations and, also transfer heat.
An exemplary combustor is disclosed comprising: a combustion chamber; an interposed cooling chamber formed of an inner liner and an outer cover plate; and a plurality of hollow elements protruding into the cooling chamber, wherein each hollow element has an open-end connected to the combustion chamber via a duct.
Further characteristics and advantages of the disclosure will be more apparent from the description of exemplary embodiments of the combustor according to the present disclosure, illustrated by way of non-limiting example in the accompanying drawings, in which:
Exemplary embodiments of the present disclosure provide a combustor by which the said problems of the known systems are eliminated.
Exemplary combustors disclosed herein can guarantee proper cooling in any operating condition, to increase its lifetime, and enable the control of NOx emissions.
Exemplary embodiments of the present disclosure provide a combustor in which the damping system is functionally integrated with the other components of the combustor and is also incorporated thereinto.
The combustor 1, including at least one of a mixing tube 2, a combustion chamber 3, and a front plate 2a, has at least a portion 4 that includes an inner liner 5 and an outer cover plate 6. The outer cover plate 6 together with the inner liner 5 establish (e.g. form, define) an interposed cooling chamber 7.
Any portions of at least one of the mixing tube 2, combustion chamber 3, and front plate 2a or also all the walls of at least one of the mixing tube 2, the combustion chamber 3, and front plate 2a may have this structure.
As shown in
As the hollow elements 9 are arranged to transfer heat to dissipate it, other exemplary embodiments having various arrangements for their disposition are possible.
The shape of the hollow elements 9 is chosen and optimised in accordance with the acceptable pressure drop. In this respect different shapes are possible for the hollow elements 9, such as cylindrical shape (
The adjustable top wall 24 of the fixing hollow elements 9f of
The operation of an exemplary combustor of the present disclosure is apparent from the description and illustrations provided above, and from an exemplary operation that follows.
The mixture formed in the mixing tube 2 is combusted in the combustion chamber 3 generating hot gases G that are expanded in a turbine (not shown). In this respect reference 27 identifies the flame.
During combustion pressure oscillations can be generated and cause hot gases to go into and out from the damping volumes 10 of the hollow elements 9, 9f via the calibrated ducts 11. These oscillations cause energy to be dissipated and, thus, the pressure oscillations to be damped. In addition, since in the cooling chamber 7 cooling air circulates (as indicated by arrow F), the mixing tube 2, the combustion chamber 3 and the front plate 2a are cooled.
Advantageously, since the hollow elements 9, 9f project into the cooling chamber 7, the cooling air impinges them such that a very intense cooling effect is achieved. When the hollow elements 9, 9f have a purge hole 13, cooling effect is further increased, because cooling air enters into the damping volume 10 via the purge hole 13 and cools the damping volume 10, and flows out from the damping volume 10 through the calibrated duct 11. This structure allows a very efficient damping effect to be achieved, because the combustor is provided with a plurality of Helmholtz dampers that if needed may also be placed along the whole wall of the combustor (i.e. mixing tube 2, combustion chamber 3 and front plate 2a).
In addition, because the damping volumes 10 can be of different sizes (volumes) and be chosen according to the desired specifications and the possibility to also introduce damping material 17 into the damping volumes 10, the structure of exemplary embodiments provided in the present disclosure can damp pressure oscillations in a very wide range. Moreover, the cooling effect is very efficient because the hollow elements 9, 9f that project into the cooling chamber 10 operate like heat exchanging fins. Cooling effect can also be increased in hollow elements 9 and/or 9f via purge holes 13.
Thus, it will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09170877.6 | Sep 2009 | EP | regional |
This application is a continuation application under 35 U.S.C. §120 to PCT/EP2010/063513 which was filed as an International application on Sep. 15, 2010 designating the U.S., and which claims priority to European Patent Application No. 09170877.6 filed in Europe on Sep. 21, 2009, the entire contents of which are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2010/063513 | Sep 2010 | US |
| Child | 13424839 | US |
