Patent Publication Number: US-10330321-B2

Title: Circumferentially and axially staged can combustor for gas turbine engine

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to PCT Patent Application No. PCT/US14/61366 filed Oct. 20, 2014, which claims priority to U.S. Provisional Application Ser. No. 61/895,169 filed Oct. 24, 2013, which are hereby incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     The present disclosure relates to a gas turbine engine and, more particularly, to a combustor section therefor. 
     Gas turbine engines generally include a compressor section to pressurize an airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases. Combustion of the hydrocarbon fuel in the presence of pressurized air may produce nitrogen oxide (NO X ) emissions that are subjected to excessively stringent controls by regulatory authorities, and thus may be sought to be minimized. 
     Dry Low NOx (DLN) combustor sections utilize a fuel-to-air lean premix strategy which operates near flame stability envelope limits where noise, flame blow-off (BO), and flashback may affect engine performance such that the DLN strategy may be limited to land-based industrial gas turbine architectures. In some DLN strategies, significant piloting is utilized to control combustion dynamics. Such strategies, although effective, may produce nitrogen oxide (NO X ) emissions that are subjected to excessively stringent controls by regulatory authorities and thus may be sought to be minimized. 
     SUMMARY 
     A combustor section for a gas turbine engine, according to one disclosed non-limiting embodiment of the present disclosure, includes a can combustor, a pilot fuel injection system and a main fuel injection system. The can combustor includes a combustion chamber. The pilot fuel injection system is in axial communication with the combustion chamber. The main fuel injection system is in radial communication with the combustion chamber. The main fuel injection system includes a multiple of first main fuel nozzles that circumferentially alternate with a multiple of second main fuel nozzles. 
     In a further embodiment of the present disclosure, the multiple of first main fuel nozzles and/or the multiple of second main fuel nozzles are fueled in pairs. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, the multiple of first main fuel nozzles are fueled through the multiple of second main fuel nozzles such that the multiple of first main fuel nozzles are each downstream to a respective one of the multiple of second main fuel nozzles. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, a valve is included in each of the multiple of second main fuel nozzles which selectively communicate fuel to a respective one of the multiple of first main fuel nozzles. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, the pilot fuel injection system includes a multiple of forward fuel injectors. One of the forward fuel injectors is within each of a multiple of can combustors. 
     A gas turbine engine, according to another disclosed non-limiting embodiment of the present disclosure, includes a compressor section, a turbine section, a combustor section, a pilot fuel injection system and a main fuel injection system. The combustion section is between the compressor section and the turbine section. The combustor section includes a multiple of can combustors each including a combustion chamber. The pilot fuel injection system is in axial communication with the combustion chamber of each of the can combustors. The a main fuel injection system is in radial communication with the combustion chamber of each of the can combustors. The main fuel injection system includes a multiple of first main fuel nozzles that alternate with a multiple of second main fuel nozzles around each of the can combustors. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, the multiple of can combustors communicate with a transition section in communication with the turbine section. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, the pilot fuel injection system includes a multiple of forward fuel injectors. One of the forward fuel injectors is within each of the multiple of can combustors. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, the multiple of first main fuel nozzles and/or the multiple of second main fuel nozzles are fueled in pairs. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, the multiple of first main fuel nozzles are fueled through the multiple of second main fuel nozzles such that the multiple of first main fuel nozzles are each downstream to a respective one of the multiple of second main fuel nozzles. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, a valve is included in each of the multiple of second main fuel nozzles which selectively communicate fuel to a respective one of the multiple of first main fuel nozzles. 
     A method of communicating fuel to a combustor section of a gas turbine engine, according to another disclosed non-limiting embodiment of the present disclosure, includes communicating pilot fuel axially into a combustion chamber; communicating fuel radially inboard into the combustion chamber; and circumferentially varying the fuel communicating radially inboard into the combustion chamber to control combustion dynamics. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, the method includes selectively communicating the fuel radially inboard into the combustion chamber through a multiple of first main fuel nozzles, and a multiple of second main fuel nozzles. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, the multiple of first main fuel nozzles are each downstream to a respective one of the multiple of second main fuel nozzles to circulate fuel through the multiple of second main fuel nozzles when the multiple of second main fuel nozzles are inactive. 
     In a further embodiment of any of the foregoing embodiments of the present disclosure, each quench zone overlaps with a respectively adjacent quench zone to define a shear region. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiments. The drawings that accompany the detailed description can be briefly described as follows: 
         FIG. 1  is a schematic view of an example gas turbine engine architecture with a combustor section having a multiple of combustor cans; 
         FIG. 2  is a schematic view of an example gas turbine engine in an industrial gas turbine environment; 
         FIG. 3  is a schematic cross-section of another example gas turbine engine; 
         FIG. 4  is a lateral schematic sectional view of the combustor section of one of a multiple of can combustors; 
         FIG. 5  is an schematic sectional view of one can combustor; and 
         FIG. 6  is a chart of example power conditions for the combustor section. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  generally includes a compressor section  24 , a combustor section  26  and a turbine section  28 . The engine  20  may be located within an enclosure  30  (see  FIG. 2 ) typical of an industrial gas turbine (IGT). Although depicted as specific engine architecture in the disclosed non-limiting embodiments, it should be understood that the concepts described herein are not limited to only such an architecture as the teachings may be applied to other gas turbine architectures with a can combustor architecture. 
     The combustor section  26  generally includes a multiple of can combustors  40  which circumferentially surround the engine central longitudinal axis A. It should be appreciated that various vertical or silo orientation arrangements may be provided for the multiple of can combustors  40  to include but not be limited to angled (shown) and axial arrangements (see  FIG. 3 ). 
     With reference to  FIG. 4 , each of the multiple of can combustors  40  receives compressed air from the compressor section  24  through an annulus  42 . The compressed airflow is communicated from the annulus  42 , through a pilot fuel injection system  44  and a main fuel injection system  46  into a combustion chamber  48  of each of the multiple of can combustors  40 . That is, the compressed airflow is directed through the annulus  42  around each combustion chamber  48  toward an end cap  50  of each can combustor  40 . The airflow passes from the annulus  42  through a multiple of nozzle swirler arrangements of the fuel injection systems  44 ,  46  from the annulus  42  to the combustion chamber  48 . The fuel and air injected by the pilot fuel injection system  44  and the main fuel injection system  46  is mixed and burned within the combustion chamber  48  of each of the multiple of can combustors  40 , then collectively communicated through a transition section  52  (also shown in  FIG. 1 ) for expansion through the turbine section  28 . Each of the multiple of can combustors  40  locates the pilot fuel injection system  44  upstream of the main fuel injection system  46  with respect to the transition section  52 . 
     The main fuel injection system  46  communicates with the combustion chamber  48  downstream of the pilot fuel injection system  44  and includes a multiple of main fuel nozzles  60  (illustrated schematically) located around each combustion chamber  48  to introduce a portion of the fuel required for desired combustion performance, e.g., emissions, operability, durability as well as to lean-out the fuel contribution provided by the pilot fuel injection system  44 . Each of the multiple of main fuel nozzles  60  are located along an axis R generally transverse to an axis F defined by an axial fuel nozzle  62  located within the end cap  50  of each can combustor  40 . 
     A radially outer fuel manifold  64  (illustrated schematically in  FIG. 5 ) of the main fuel injection system  46  communicates fuel to each of the multiple of main fuel nozzles  60 . Each of the multiple of main fuel nozzles  60  directs the fuel through a main swirler  66  located coaxially with a radial outer port  68  to communicate an air-fuel mixture into the combustion chamber  48 . 
     With reference to  FIG. 5 , the multiple of main fuel nozzles  60  and associated swirlers  66  (see  FIG. 4 ) of the main fuel injection system  46  includes alternating first main fuel nozzles  60 A that alternate with a multiple of second main fuel nozzles  60 B around the combustion chamber  48 . It should be appreciated that “alternate” as defined herein includes various patterns such as  60 A,  60 B,  60 A . . . ;  60 A,  60 A,  60 B,  60 B,  60 A . . . etc. 
     The first and second main fuel nozzles  60 A,  60 B in the disclosed non-limiting embodiment receive fuel from the radially outer fuel manifold  64  in pairs. In this disclosed non-limiting embodiment, a fuel stem  70  from the radially outer fuel manifold  64  communicates fuel to one of the first multiple of main fuel nozzles  60 A first through an adjacent one of the multiple of second main fuel nozzles  60 B. That is, each of the multiple of main fuel nozzle  60 A are downstream to an associated one of the multiple of second main fuel nozzles  60 B with respect to fuel flow. 
     A valve  72  (illustrated schematically) is associated with each of the multiple of second main fuel nozzles  60 B such that under an example low power condition and partial power condition, the valve  72  is closed to direct fuel to the one of the first multiple of main fuel nozzle  60 A yet circulates fuel with respect to the multiple of second main fuel nozzles  60 B to avoid fuel coking therein. That is, each fuel stem  70  feeds one of the multiple of first main fuel nozzles  60 A and thru the valve  72 , one of the multiple of second main fuel nozzles  60 B of each associated pair fueled by that fuel stem  70 . 
     In one disclosed non-limiting embodiment (see  FIG. 6 ), under a low power condition such as idle, the pilot fuel injection system  44  receives 100% of the fuel while the first and second multiple of main fuel nozzles  60 A,  60 B receive 0% of the fuel. Under a partial power condition, the pilot fuel injection system  44  receives about 20%-40% of the fuel, the multiple of first main fuel nozzles  60 A receive the balance of about 80%-60% of the fuel and the multiple of second main fuel nozzles  60 B receive 0% of the fuel as the valve  72  is closed. That is, the fuel distribution is axially variable in each can combustor  40 . Notably, the fuel circulates thru at least a portion of the multiple of second main fuel nozzles  60 B when the valve  72  is closed prior to communication to the respective multiple of first main fuel nozzles  60 A of each pair. Under a high power condition, the pilot fuel injection system  44  receives about 20% of the fuel, the multiple of first main fuel nozzles  60 A receive about 30%-40% of the fuel and the multiple of second main fuel nozzles  60 B also receive about 30%-40% of the fuel as the valve  72  is open. 
     The pilot fuel injection system  44  maintains stability at low power while the axially staged main fuel injection system  46  facilitates control of heat release axially to control longitudinal acoustic modes. The main fuel injection system  46  may also be circumferentially staged to control heat release and thereby control tangential acoustic modes and may also be premixed to control emissions. Advantageously, other fuel distributions may alternatively or additionally be provided for these as well as other operational conditions. For example, the fuel distribution between the first and multiple of second main fuel nozzles  60 A,  60 B may be readily circumferentially varied to control combustion dynamics. Such control of combustion dynamics may additionally be utilized to vary the acoustic field within the combustor  56 . 
     The pilot fuel injection system  44  facilitates stability at all power levels, while the main fuel injection system  46  provides axially staged injection and circumferentially staged injection controllability. NOx formation is not only a function of temperature, but also of flame residence time and Oxygen concentration in the reaction zone. Increasing the flame strain tends to reduce the residence time in the flame, but may also increase the Oxygen concentration in the flame. These intermediate effects of strain rates tend to increase the production rate of NOx. At high strain rates, however, the reduction in flame temperature overcomes the influence of the Oxygen concentration, and NOx production rates are reduced. 
     The use of the terms “a” and “an” and “the” and similar references in the context of description (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. It should be appreciated that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting. 
     Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
     It should be appreciated that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be appreciated that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. 
     Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
     The foregoing description is exemplary rather than defined by the features within. Various non-limiting embodiments are disclosed herein; however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be appreciated that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.