Patent Application
20160053999
The subject matter disclosed herein relates to the art of turbomachines and, more particularly to a combustor for a gas turbomachine.
Turbomachines typically include a compressor portion and a turbine portion. The compressor portion forms a compressed air stream that is introduced into the turbine portion. In a gas turbomachine, a portion of the compressed airstream mixes with products of combustion forming a hot gas stream that is introduced into the turbine portion through a transition piece. In some cases, the products of combustion include un-combusted constituents that contribute to undesirable emissions.
The hot gas stream impacts turbomachine airfoils arranged in sequential stages along the hot gas path. The airfoils are generally connected to a wheel which, in turn, may be connected to a rotor. Typically, the rotor is operatively connected to a load. The hot gas stream imparts a force to the airfoils causing rotation. The rotation is transferred to the rotor. Thus, the turbine portion converts thermal energy from the hot gas stream into mechanical/rotational energy that is used to drive the load. The load may take on a variety of forms including a generator, a pump, an aircraft, a locomotive or the like.
According to an aspect of an exemplary embodiment, a combustor for a turbomachine includes a combustor body, and a combustor liner arranged in the combustor body and defining a combustion chamber extending from a head end to a combustor discharge. The combustor liner is spaced from the combustor body forming a compressor discharge casing (CDC) airflow passage. At least one nozzle is arranged at the head end of the combustor liner. The at least one nozzle includes an outlet configured and disposed to establish a flame zone. At least one recirculation member is arranged at the head end of the combustor liner. The at least one recirculation member is configured and disposed to guide oxygen-depleted combustion products from the flame zone back to the outlet of the at least one nozzle.
According to another aspect of an exemplary embodiment, a gas turbomachine includes a compressor portion, a turbine portion operatively connected to the compressor portion, and a combustor assembly including at least one combustor fluidically connecting the compressor portion and the turbine portion. The at least one combustor includes a combustor body, and a combustor liner arranged in the combustor body and defining a combustion chamber extending from a head end to a combustor discharge. The combustor liner is spaced from the combustor body forming a compressor discharge casing (CDC) airflow passage. At least one nozzle is arranged at the head end of the combustor liner. The at least one nozzle includes an outlet configured and disposed to establish a flame zone. At least one recirculation member is arranged at the head end of the combustor liner. The at least one recirculation member is configured and disposed to guide oxygen-depleted combustion products from the flame zone back to the outlet of the at least one nozzle.
According to yet another aspect of an exemplary embodiment, a gas turbomachine system includes a compressor portion, a turbine portion operatively connected to the compressor portion, an air inlet system fluidically connected to the compressor portion, a load operatively connected to one of the compressor portion and the turbine portion, and a combustor assembly including at least one combustor fluidically connecting the compressor portion and the turbine portion. The at least one combustor includes a combustor body, and a combustor liner arranged in the combustor body and defining a combustion chamber extending from a head end to a combustor discharge. The combustor liner is spaced from the combustor body forming a compressor discharge casing (CDC) airflow passage. At least one nozzle is arranged at the head end of the combustor liner. The at least one nozzle includes an outlet configured and disposed to establish a flame zone. At least one recirculation member is arranged at the head end of the combustor liner. The at least one recirculation member is configured and disposed to guide oxygen-depleted combustion products from the flame zone back to the outlet of the at least one nozzle.
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.
With initial reference to
Compressor portion 4 includes a diffuser 22 and a compressor discharge plenum 24 that are coupled in flow communication with each other and combustor assembly 8. With this arrangement, compressed air is passed through diffuser 22 and compressor discharge plenum 24 into combustor assembly 8. The compressed air is mixed with fuel and combusted to form hot gases. The hot gases are channeled to turbine portion 6. Turbine portion 6 converts thermal energy from the hot gases into mechanical/rotational energy.
Combustor 9 includes a combustor body 30 having a combustor cap 33 and a combustor liner 36. As shown, combustor liner 36 is positioned radially inward from combustor body 30 so as to define a combustion chamber 38. Combustion chamber 38 extends from a head end 39 to a compressor discharge 40. Combustor liner 36 is spaced from combustor body 30 forming a compressor discharge casing (CDC) airflow passage 43. A transition piece 45 connects combustor assembly 8 to turbine portion 6. Transition piece 45 channels combustion gases generated in combustion chamber 38 downstream towards a first stage (not separately labeled) of turbine portion 6. Transition piece 45 may include an inner wall 48 and an outer wall 49 that define an annular passage 54 that fluidically connects with CDC airflow passage 43. Inner wall 48 may also define a guide cavity 56 that extends between combustion chamber 38 and turbine portion 6. A nozzle assembly 60 is arranged at head end 39 of combustion liner 36. Nozzle assembly 60 includes one or more nozzles such as indicated at 62.
In accordance with an aspect of an exemplary embodiment, combustor 9 includes a recirculation member 80 arranged at head end 39. As shown in
In further accordance with an exemplary embodiment, inner surface 92 defines an interior cavity 96. A plurality of openings, one of which is shown at 100, extend through each of first, second, and third surface sections 86-88 fluidically connecting interior cavity 96 and combustion chamber 38. A plurality of guide elements, one of which is indicated at 104, are mounted to outer surface 90 at each of the plurality of openings 100. Each guide element 104 extends from a first end 106 coupled to outer surface 90 to a second, cantilevered end 107 through a bend portion 109. As will be discussed more fully below, guide elements 104 direct fluid passing from interior cavity 96 to flow along one of first, second, and third surface sections 86-88.
In still further accordance with an exemplary embodiment, combustor 9 includes a recirculation passage 115 arranged radially outwardly of recirculation member 80. A plurality of conduits, two of which are shown at 122 and 123, fluidically connect CDC airflow passage 43 and interior cavity 96. One or more of the plurality of conduits 122 and 123 may constitute an aerodynamically shaped vane 126. Specifically, one or more of conduits 122 and 123 may include an aerodynamically shaped cross-section in the shape of an airfoil, such as shown at 130. Of course, aerodynamically shaped vane 126 may include other profile geometries. Aerodynamically shaped vane 126 conditions an oxygen-depleted flow passing from combustion chamber 38 through recirculation passage 115, as will be detailed more fully below.
In accordance with an aspect of an exemplary embodiment, a flame 200 is established in combustion chamber 38. Flame 200 includes a base or root 210 arranged proximate to nozzle 60. Flame 200 establishes a flame zone 220 in which oxygen-depleted combustion products such as NOx are formed. Generally, the oxygen-depleted combustion products migrate radially outwardly in combustion chamber 38 toward combustor liner 36. In order to enhance combustor efficiency and reduce emissions, the oxygen-depleted combustion products are directed back to root 210 of flame 200 in flame zone 220.
More specifically, compressor air flowing through CDC airflow passage 43 passes into interior cavity 96 of recirculation member 80. The compressor air passes through openings 100 and is guided by guide element 104 about recirculation member 80 forming a low pressure zone at recirculation passage 115. The oxygen-depleted combustion products are drawn toward the low pressure zone (not separately labeled) and pass through recirculation passage 115. The oxygen-depleted combustion products mix with the compressor air and passes back to root 210 of flame 200 to be further combusted. In accordance with an aspect of an exemplary embodiment, the compressor air trips over a corner (not separately labeled) formed at a junction of first surface section 86 and second surface section 87 creating the low pressure zone. In accordance with another aspect of an exemplary embodiment, aerodynamically shaped vanes 126 reduce drag on the oxygen-depleted combustion products passing through recirculation passage 115 to enhance flow toward root 210.
At this point it should be understood that the exemplary embodiments describe a combustor having a recirculation member that creates a low pressure zone in a radially outer section of a combustion chamber. The low pressure zone draws in oxygen-depleted combustion products to mix with compressor air prior to being re-introduced to a flame zone. In this manner, the oxygen-depleted combustion products may be further combusted to improve combustor efficiency and reduce emissions.
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.
