Patent Application
20140060072
The subject matter disclosed herein relates to gas turbine systems, and more particularly to a method of starting a gas turbine system.
Reliable starting of the gas turbine system includes successful “light-off” of a fuel, such as a liquid fuel. Successful light-off is dependent upon an appropriate level of firing fuel flow during a firing attempt, among other things. Overall, firing occurs inside an envelope of a maximum allowable firing time and a maximum allowable amount of fuel. Typically, a single constant firing fuel flow setting is employed during a starting process, however, a variety of factors associated with the starting process may lead to different firing fuel flow settings being beneficial. In such a way, various firing fuel flow settings may lead to more efficient and reliable starting processes based on the number of factors alluded to above.
According to one aspect of the invention, a method of starting a gas turbine system is provided. The method includes approximating a temperature of at least one turbine system component. Also included is selectively determining a flow rate for a fuel to be delivered to a combustor for combustion therein, wherein the flow rate is dependent upon the temperature of the at least one turbine system component. Further included is delivering the fuel to the combustor at the flow rate selectively determined.
According to another aspect of the invention, a method of starting a gas turbine system is provided. The method includes determining a temperature of a turbine system component. Also included is determining whether the temperature is within a first range, a second range or a third range. Further included is delivering a fuel to a combustor at a first fuel flow rate if the temperature is within the first range. Yet further included is delivering the fuel to the combustor at a second fuel flow rate if the temperature is within the second range. Also included is delivering the fuel to the combustor at a third fuel flow rate if the temperature is within the third range, wherein the third range is between the first range and the second range.
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.
Referring to
The combustor 14 uses a combustible liquid and/or gas fuel, such as natural gas or a hydrogen rich synthetic gas, to run the gas turbine system 10. For example, fuel nozzles 20 are in fluid communication with an air supply and a fuel supply 22. The fuel nozzles 20 create an air-fuel mixture, and discharge the air-fuel mixture into the combustor 14, thereby causing a combustion that creates a hot pressurized exhaust gas. The combustor 14 directs the hot pressurized gas through a transition piece into a turbine nozzle (or “stage one nozzle”), and other stages of buckets and nozzles causing rotation of the turbine 16 within a turbine casing 24. Rotation of the turbine 16 causes the shaft 18 to rotate, thereby compressing the air as it flows into the compressor 12.
An embodiment of the gas turbine system 10, and more specifically the combustor 14, employing liquid fuel for combustion purposes requires the provision of liquid fuel to the combustor 14 for combustion therein. The liquid fuel is supplied at various flow rates that are dependent upon various parameters associated with the gas turbine system 10, such as the temperature of one or more turbine system components. Successful “light-off” of liquid fuel is dependent upon an appropriate flow rate of liquid fuel during a firing attempt of the gas turbine system 10. To reliably produce successful light-off, various parameters, such as temperature as noted above, are taken into account to determine the appropriate flow rate of liquid fuel to be provided during the firing attempt. Generally speaking, during a relatively “cold start,” a greater flow rate of fuel is appropriate, when compared to a relatively “hot start.” This is based on the increased likelihood of a “choking out” of a combustor flame if too much fuel is supplied during the hot firing attempt. Conversely, during a colder start, too low of a flow rate will result in a diminished likelihood of successful light-off.
Referring now to
The at least one turbine system component employed to make the thermal determination of the gas turbine system 10 may include a variety of gas turbine components. Examples of components or regions of the gas turbine system 10 that may be employed include the combustor 14, a compressor inlet region, a compressor discharge region, a turbine section exhaust region, an outer casing of the turbine 16 or the compressor 12, and the wheel space of the turbine 16, such as the first stage wheel space that is disposed proximate an outlet of the combustor 14. It is to be understood that the preceding examples are merely illustrative and are not intended to be limiting of components and/or regions that may be employed to determine the thermal state of the gas turbine system 10.
Referring now to
As illustrated, the first embodiment includes determining whether the temperature of the at least one turbine system component is above or below a predetermined temperature 106. The predetermined temperature 106 corresponds to a temperature that delineates a cold start and a hot start. A first flow rate 108 or a second flow rate 110 is selected based on the determination of whether the at least one turbine system component is above or below the predetermined temperature 106. The first flow rate 108 corresponds to a cold start, where the temperature of the at least one turbine system component is below the predetermined temperature 106. Conversely, the second flow rate 110 corresponds to a hot start, where the temperature of the at least one turbine system component is above the predetermined temperature 106. As shown, the first flow rate 108 is greater than the second flow rate 110, based on the above-described desirability to provide more liquid fuel during a cold firing attempt than during a hot firing attempt.
Referring now to
As noted above, the third fuel flow rate 216 is variable and is a function of temperature. The third range 210 defines a range of temperatures that are not characterized as hot or cold and the varying rate of liquid fuel delivered at temperatures over the third range 210 increases efficiency of the gas turbine system 10, and more particularly the combustion process by increasing the reliability of successful light-off of the fuel during the firing attempt. Rather than providing a constant flow rate over the third range 210, the third fuel flow rate 216 is a function of temperature and may be of a linear variance. The precise flow rates over the third range 210 may be linearly interpolated between the first range 202 and the second range 206 or may be empirically determined.
Irrespective of the method of determining the precise flow rates comprising the third fuel flow rate 216 over the third range 210, the flow diagram of
Advantageously, an efficient and reliable firing fuel flow is selected based on determining the state (i.e., thermal condition) of the gas turbine system 10 at firing and employing a firing fuel flow rate based on the state of the gas turbine system 10. Such a system and method reduces cost and reliability problems of liquid fuel fired gas turbine systems during starting procedures.
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.
