Patent Application
20160053681
The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a liquid fuel combustor having an oxygen-depleted gas (ODG) injection system 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.
In some cases, combustors may combust liquid fuels such as heavy fuel oil (HFO) or a combination of liquid and gaseous fuels. Liquid fuels are generally atomized upon introduction to the combustion chamber. Atomization of the liquid fuels produces droplets that are exposed to an ignition source and combusted. In some cases, larger droplets tend to migrate radially outward and may remain un-combusted. Un-combusted fuel may flow through the turbomachine and exit with exhaust gases contributing to emissions such as CO, unburned hydrocarbons, or UHC, and the like that are currently subject to regulation.
According to one aspect of an exemplary embodiment, a liquid fuel combustor for a gas turbomachine includes a combustor body and a combustor liner arranged in the combustor body 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 a first inlet, a second inlet, and an outlet configured and disposed to establish a flame zone. The first inlet is configured to receive a first fluid and the second inlet is configured to receive a second fluid. The second fluid includes a liquid fuel. An oxygen-depleted gas (ODG) injection system is arranged radially outwardly of the at least one nozzle. The ODG injection system is configured and disposed to deliver an oxygen-depleted gas stream into the combustion chamber to vaporize a portion of the second fluid.
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 liquid fuel combustor fluidically connecting the compressor portion and the turbine portion. The at least one liquid fuel combustor includes a combustor body and a combustor liner arranged in the combustor body 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 a first inlet, a second inlet, and an outlet configured and disposed to establish a flame zone. The first inlet is configured to receive a first fluid and the second inlet is configured to receive a second fluid. The second fluid includes a liquid fuel. An oxygen-deplete gas (ODG) injection system is arranged radially outwardly of the at least one nozzle. The ODG injection system is configured and disposed to deliver an oxygen-depleted gas stream into the combustion chamber to vaporize a portion of the second fluid.
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 liquid fuel combustor fluidically connecting the compressor portion and the turbine portion. The at least one liquid fuel combustor includes a combustor body and a combustor liner arranged in the combustor body 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 a first inlet, a second inlet, and an outlet configured and disposed to establish a flame zone. The first inlet is configured to receive a first fluid and the second inlet is configured to receive a second fluid. The second fluid includes a liquid fuel. An oxygen-depleted gas (ODG) injection system is arranged radially outwardly of the at least one nozzle. The ODG injection system is configured and disposed to deliver an oxygen-depleted gas stream into the combustion chamber to vaporize a portion of the second fluid in oxygen-depleted combustion products.
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 fluidic 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.
Liquid fuel 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 combustor liner 36. Nozzle assembly 60 includes at least one nozzle indicated at 62.
In accordance with an aspect of an exemplary embodiment illustrated in
In accordance with an aspect of an exemplary embodiment, liquid fuel combustor 9 includes an oxygen-depleted gas (ODG) injection system 83 arranged radially outwardly of nozzle 62. ODG injection system 83 introduces a hot oxygen-depleted gas stream into combustion chamber 38. The oxygen-depleted gas stream may be at a temperature in a range of 250° F. (121° C.) to 1800° F. (982° C.) and facilitates combustion of un-combusted fuel particles, such as droplets 81 that may migrate radially outwardly of flame zone 80. Of course, it should be understood that the temperature range may vary. Oxygen-depleted gases may originate at liquid fuel combustor 9, or may be introduced from a different source. Regardless of the source of the oxygen-depleted gas, ODG injection system 83 promotes more complete vaporization of the combustible mixture to reduce emissions, such as NOx.
In accordance with an aspect of an exemplary embodiment, ODG injection system 83 takes the form of a recirculation member 84 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, liquid fuel combustor 9 includes a recirculation passage 115 arranged radially outwardly of recirculation member 84. 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 62. 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 into combustion chamber 38 toward un-combusted droplets 230 that may migrate radially outwardly of flame zone 220 and toward root 210 of flame 200 to enhance combustion.
More specifically, compressor air flowing through CDC airflow passage 43 passes into interior cavity 96 of recirculation member 84. The compressor air passes through openings 100 and is guided by guide element 104 about recirculation member 84 forming a low pressure zone (not separately labeled) at recirculation passage 115. The oxygen-depleted combustion products are drawn toward the low pressure zone and pass through recirculation passage 115. The oxygen-depleted combustion products mix with the compressor air and pass back into combustion chamber 38 to enhance combustion of un-combusted fuel particles/droplets. In accordance with an aspect of the exemplary embodiment, the oxygen-deplete gas captures/transports droplets 230 back toward a base of flame 200.
In accordance with another 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 into combustion chamber 38.
At this point it should be understood that the exemplary embodiments describe a combustor having an oxygen-depleted gas (ODG) injection system that introduces an oxygen-depleted gas back into the combustion chamber to promote combustion of un-combusted fuel particles. The oxygen-depleted gas may originate in combustion chamber 38, may mix with compressor gas, or may be introduced from a remote source. Regardless of the source, the oxygen-depleted gas mixes with un-combusted fuel particles to promote combustion. In accordance with one aspect of the exemplary embodiment, the oxygen-depleted gases may mix with, capture, and carry the un-combusted fuel particles back toward a base of a combustor flame 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.
