The present invention generally involves a combustor and method for conditioning flow through the combustor. In particular embodiments of the present invention, one or more modular inserts may be installed inside the combustor to reduce the combustion dynamics and/or recirculation zones inside the combustor.
Combustors are commonly used in industrial and power generation operations to ignite fuel to produce combustion gases having a high temperature and pressure. For example, gas turbines typically include one or more combustors to generate power or thrust. A typical gas turbine used to generate electrical power includes an axial compressor at the front, one or more combustors around the middle, and a turbine at the rear. Ambient air may be supplied to the compressor, and rotating blades and stationary vanes in the compressor progressively impart kinetic energy to the working fluid (air) to produce a compressed working fluid at a highly energized state. The compressed working fluid exits the compressor and flows through one or more nozzles into a combustion chamber in each combustor where the compressed working fluid mixes with fuel and ignites to generate combustion gases having a high temperature and pressure. The combustion gases expand in the turbine to produce work. For example, expansion of the combustion gases in the turbine may rotate a shaft connected to a generator to produce electricity.
Various operating parameters influence the design and operation of combustors. For example, higher combustion gas temperatures generally improve the thermodynamic efficiency of the combustor. However, higher combustion gas temperatures also promote flashback or flame holding conditions in which the combustion flame migrates towards the fuel being supplied by the nozzles, possibly causing severe damage to the nozzles in a relatively short amount of time. In addition, higher combustion gas temperatures generally increase the disassociation rate of diatomic nitrogen, increasing the production of nitrogen oxides (NOx). A leaner fuel-working fluid stoichiometry and/or water or steam injection into the combustion chamber may reduce flame temperatures and NOx production. However, the leaner fuel mixture and/or water or steam injection may create vibrations and/or pressure pulses collectively referred to as combustion dynamics.
Increased combustion dynamics may adversely affect the useful life of the combustor hardware and/or downstream components. Alternately, or in addition, high frequencies of combustion dynamics may produce pressure pulses inside the nozzles and/or combustion chamber that affect the stability of the combustion flame, reduce the design margins for flashback or flame holding, and/or increase undesirable emissions. Therefore, a combustor and method that conditions flow through the combustor to reduce combustion dynamics would be useful to enhancing the thermodynamic efficiency of the combustor, protecting the combustor from catastrophic damage, and/or reducing undesirable emissions over a wide range of combustor operating levels.
Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.
One embodiment of the present invention is a combustor that includes an end cover and a casing adjacent to the end cover, wherein the end cover and casing at least partially define a volume inside the combustor. The combustor further includes an end cap that extends radially across at least a portion of the combustor, at least one nozzle arranged in the end cap to provide fluid communication through the end cap, and means for conditioning flow through the volume.
Another embodiment of the present invention is a combustor that includes an end cover and a casing adjacent to the end cover, wherein the end cover and casing at least partially define a volume inside the combustor. An end cap extends radially across at least a portion of the combustor, and at least one nozzle is arranged in the end cap to provide fluid communication through the end cap. The combustor further includes at least one of an annular insert adjacent to the end cover, a first arcuate insert adjacent to the end cover, or a second arcuate insert adjacent to the end cap, wherein the second arcuate insert has a convex surface.
Embodiments of the present invention may also include a method for conditioning flow through a combustor. The method includes flowing a working fluid through a volume at least partially defined by an end cover, a casing, and an end cap that extends radially across at least a portion of the combustor and flowing the working fluid across an annular insert adjacent to the end cover.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.
Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Various embodiments of the present invention include a combustor and method for conditioning flow through the combustor. In particular embodiments, one or more modular inserts may be installed inside the combustor to reduce the acoustic volume and/or recirculation zones inside the combustor, producing a corresponding decrease in the pressure drop across the combustor and/or dynamics produced by the combustor. The optimum location, number, size, and shape of the modular inserts may be readily determined by one of ordinary skill in the art through computational fluid dynamics calculations and/or validated in laboratory testing. Although exemplary embodiments of the present invention will be described generally in the context of a combustor incorporated into a gas turbine for purposes of illustration, one of ordinary skill in the art will readily appreciate that embodiments of the present invention may be applied to any combustor and are not limited to a gas turbine combustor unless specifically recited in the claims. In addition, as used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify particular structure, location, function, or importance of the individual components.
The various embodiments of the present invention include means for conditioning flow through the volume 16. As used herein, the function “conditioning flow through the volume” includes improving one or more features of the working fluid flowing through the head end. For example, the function “conditioning flow through the volume” may include reducing the size of low flow regions or areas in the head end to reduce the differential pressure of the working fluid across the head end. Alternately or in addition, the function “conditioning flow through the volume” may include reducing the acoustic volume of the head end to reduce combustion dynamics produced by the working fluid flowing through the head end.
The structure for “conditioning flow through the volume” may include one or more modular inserts as shown, for example, in
Alternately or in addition, the means for conditioning flow may include one or more arcuate inserts 50, alone or in combination with the annular insert 40, as shown in
In the particular embodiment shown in
In still further embodiments within the scope of the present invention, the structure for “conditioning flow through the volume” may include one or more modular inserts as shown, for example, in
The various embodiments of the present invention shown in
The various embodiments shown and described with respect to
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.