Patent Application
20100275573
The subject matter disclosed herein relates to fuel nozzle flashback detection.
A combustor of a gas turbine engine has a combustion zone defined therein and includes one or more fuel nozzles that provide combustible materials to the combustion zone. The fuel nozzles include arrangements of one or more burners that each have passages defined therein through which the combustible materials, such as mixtures of fuel and air, travel toward the combustion zone. As the combustible materials reach the aft ends of the burners, they are ignited and combust. Generally, this combustion occurs within the primary and secondary recirculation zones of the combustion zone and, while, temperatures at the burners can reach relatively highly elevated levels, these temperatures are usually within established temperature parameters for burner operation without significant damage.
Occasionally, however, flashbacks occur. During flashbacks combustion of the combustible materials takes place abnormally close to or within the burners and temperatures at the burners exceed the established temperature parameters. Since the burner components are not typically designed to withstand such conditions, damage to the burners and the fuel nozzles can ensue. This damage may necessitate a costly shutdown of the gas turbine engine, repairs and/or replacement of the burners and the fuel nozzles.
Mitigating a likelihood of a flashback for any particular fuel nozzle or burner can involve designing the fuel nozzle with a 20% margin on burner tube velocity for given fuels. That is, each particular fuel nozzle is designed for use with selected fuels with the expectation that certain quantities of those fuels would be supplied to the fuel nozzles at certain velocities during gas turbine operations. Drawbacks associated with the 20% margin exist, however, in that alternate fuels cannot be substituted for the given fuels at a later date without, at least, significant testing and damage risks.
According to one aspect of the invention, a combustor of a turbine engine having a combustion zone defined therein is provided and includes a fuel nozzle, including two or more burners, each of the burners having a passage defined therein through which combustible materials are permitted to travel toward the combustion zone, a plurality of sensors disposed in relative association with each of the burners to respectively sense static pressures within the passages of each of the burners and to respectively issue sensed static pressure signals accordingly, and a controller, coupled to the sensors and receptive of the signals, which is configured to determine from an analysis of the signals whether any of the burners are associated with a flashback risk and to mitigate the flashback risk in accordance with the determination.
According to another aspect of the invention, a burner of a fuel nozzle of a turbine engine combustor having a combustion zone defined therein is provided and includes an annular shroud terminating at a forward end of the combustor, a center body disposed within the annular shroud to define an annular passage extending between the annular shroud and the center body through which combustible materials travel toward the combustion zone, and a plurality of sensors, which are disposed in relative association with the shroud, to respectively sense static pressures within the passage and to respectively issue sensed static pressure signals accordingly for use in determining a flashback risk and for use in mitigating the flashback risk.
According to yet another aspect of the invention, a method of controlling a fuel nozzle of a turbine engine combustor, including two or more burners, is provided and includes sensing static pressures within a passage defined in each of the burners, analyzing the static pressures to calculate an average static pressure within the passage in each of the burners, comparing the average static pressures with one another, determining from a result of the comparison whether one or more of the burners is associated with a flashback risk, and mitigating the flashback risk associated with the one or more of the burners in accordance with the determination.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
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The combustible materials include mixtures of air and fuel in varying quantities based on turbine engine load requirements, emissions requirements and additional considerations. The air may be provided as compressed air produced by a compressor that enters the passage 80 by way of inlets 90 and 91. The fuel may be provided as varied types of premixed fuel, diffusion fuel and/or liquid fuel and is delivered in at least one or more of these forms to the annular passage 80 via fuel injectors 92 by way of a fuel delivery system 100, coupled to a fuel source, which includes lines 101, 102 and 103. Valves 110 are provided along each line 101, 102 and 103 that allow for quantities of fuel deliverable to the passage 80 to be controlled.
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While the pressure sensor 120 configurations described above relate to configurations of three or more pressure sensors 120 for each burner 60, these configurations are merely exemplary and it is understood that configurations of one or two pressure sensors 120 are possible.
The combustor 20 further includes a controller 130, which is coupled to each of the pressure sensors 120. The controller 130 is receptive of the sensed static pressure signals and includes a processing unit 131 and a memory unit 132, which is coupled to the processing unit 131. The memory unit 132 may be embodied as a computer readable medium having executable instructions stored thereon, which, when executed, cause the processing unit 131 to determine from an analysis of the signals whether any of the burners 60 are associated with a flashback risk.
The processing unit 131 analyses the signals by first calculating an average static pressure within the passages 80 of each of the burners 60. The processing unit 131, acting as a comparator, then compares the average static pressures of each of the burners 60 to one another. Here, the processing unit 131 judges that one or more of the burners 60 is associated with the flashback risk if the average static pressures within their respective passages 80 are less than the averages of the other ones of the burners by a threshold level. The threshold level may be established by testing done at the point of burner 60 manufacture. The threshold level may also be updated throughout the lifecycle of the turbine engine in accordance with ongoing performance analyses.
With the processing unit 131 of the controller 130 judging that a burner 60 is associated with a flashback risk, the controller 130 is further configured to mitigate the flashback risk. To this end, the controller 130 may be controllably coupled to at least the valves 110 of the fuel delivery system 100. In this way, the controller 130 may open or close the valves 110 in order to increase or decrease an amount of fuel deliverable to the burner 60 at risk. Thus, an at-risk burner 60 can be starved of fuel by way of the closing of its associated valve 110 and a flashback incident with respect to that burner 60 can be avoided. Additionally or alternatively, the controller 130 may be configured to decrease a turbine engine load. In this way, an overall fuel demand of the turbine engine is lowered along with temperatures within at least the combustion zone 21. Here, the possibility of flashback occurring in any particular burner 60 is correspondingly decreased.
With reference to
As described above, the determining includes judging that the one or more of the burners 60 is associated with the flashback risk if corresponding ones of the average static pressures are less than the average static pressures of other ones of the burners 60 by a threshold level. Similarly, the mitigating includes decreasing an amount of fuel deliverable to the one or more of the at-risk burners 60 and/or decreasing a turbine engine load.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
