SYSTEM AND METHOD FOR COMBUSTION OF NON-GASEOUS FUELS AND DERIVATIVES THEREOF

Abstract

The present disclosure relates to apparatuses and methods that are useful for one or more aspects of a power production plant. More particularly, the disclosure relates to combustor apparatuses and methods for a combustor adapted to utilize different fuel mixtures derived from gasification of a solid fuel. Combustion of the different fuel mixtures within the combustor can be facilitated by arranging elements of the combustor controlled so that a defined set of combustion characteristics remains substantially constant across a range of different fuel mixtures.

Claims

1. A power production plant comprising: a gasifier configured for receiving a solid fuel and providing a gaseous fuel; a combustor configured for receiving the gaseous fuel, an oxidant, and a diluent, and outputting a combustor exhaust stream; and a turbine configured to receive the combustor exhaust stream; wherein the combustor includes an outer casing and a combustor liner defining a combustion chamber therein, at least a portion of an outer surface of the combustor liner being configured to receive a flow of any one or more of the fuel, the oxidant, and the diluent thereagainst prior to being received by the combustion chamber to thereby provide for cooling of the combustor liner.

2. The power production plant of claim 1, wherein the outer surface of the combustor liner includes a periphery and a length, and wherein substantially the entirety of the outer surface of the combustor liner, about the periphery and along the length thereof, is configured to receive the flow of any one or more of the fuel, the oxidant, or the diluent thereagainst prior to being received by the combustion chamber.

3. The power production plant of claim 1, wherein the combustor liner comprises a plurality of longitudinally-extending reinforcing rib members engaged with the outer surface of the combustor liner, wherein at least a portion of the outer surface of the combustor liner between adjacent reinforcing rib members is configured to receive the flow of any one or more of the fuel, the oxidant, and the diluent thereagainst prior to being received by the combustion chamber.

4. The power production plant of claim 3, further comprising a sleeve member extending about the outer surface of the combustor liner and the plurality of reinforcing rib members, the sleeve member cooperating with at least the reinforcing rib members to define a plurality of longitudinally-extending cooling channels about the outer surface of the combustor liner, the flow of any one or more of the fuel, the oxidant, and the diluent being directed through the cooling channels and against the outside surface of the combustion chamber prior to being received by the combustion chamber.

5. The power production plant of claim 1, wherein the combustor liner comprises one or more openings defined therein and adapted for passage therethrough of the oxidant into the combustion chamber.

6. The power production plant of claim 1, wherein the combustor liner comprises one or more openings defined therein and adapted for passage therethrough of the diluent into the combustion chamber.

7. The power production plant of claim 1, wherein the combustor liner comprises a first, inner liner and a second, outer liner.

8. The power production plant of claim 7, wherein the inner liner and the outer liner are spaced apart so as to define a space therebetween, the space being adapted for passage therethrough of the diluent.

9. The power production plant of claim 1, wherein the combustion chamber defines a reaction zone and a dilution zone.

10. The power production plant of claim 1, wherein the combustor further comprises an oxidant injector engaging an upstream end of the combustor liner.

11. The power production plant of claim 10, wherein the oxidant injector comprises a first stage oxidant injector arranged to introduce at least a first portion of at least the oxidant into the combustion chamber.

12. The power production plant of claim 11, wherein the first stage oxidant injector includes a swirler device configured to direct the oxidant into the combustion chamber at an angle relative to axial.

13. The power production plant of claim 12, wherein the swirler device comprises a plurality of angled oxidant vents configured to direct the oxidant into the combustion chamber at an angle of about 20 degrees to about 85 degrees relative to axial.

14. The power production plant of claim 10, wherein the oxidant injector includes a passage therethrough configured for engagement by a fuel nozzle.

15. The power production plant of claim 11, wherein the oxidant injector comprises a second stage oxidant injector arranged to introduce a second portion of at least the oxidant through a wall of the combustor liner defining the combustion chamber.

16. The power production plant of claim 15, wherein the second stage oxidant injector is arranged relative to the first stage oxidant injector so that the second portion of at least the oxidant is introduced through the wall of the combustor liner downstream from the first stage oxidant injector.

17. A power production plant comprising: a gasifier configured for receiving a solid fuel and providing a gaseous fuel; a combustor having a combustor liner defining a combustion chamber configured for receiving the gaseous fuel, an oxidant, and a diluent, and outputting a combustor exhaust stream, the combustion chamber defining a reaction zone and a dilution zone; and an injection arrangement configured to inject at least the oxidant into the combustion chamber of the combustor, the injection arrangement including: a first stage oxidant injector engaging an end of the combustor liner, the first stage oxidant injector being arranged to introduce a first portion of at least the oxidant into the reaction zone of the combustion chamber through a swirler device, the swirler device of the first stage oxidant injector providing for mixing of the oxidant with the fuel, and producing recirculation about the reaction zone; and a second stage oxidant injector arranged to introduce a second portion of at least the oxidant into the reaction zone, through a wall of the combustor liner defining the combustion chamber, downstream of the first stage oxidant injector and prior to the dilution zone of the combustion chamber, the second stage oxidant injector being configured to stabilize a flame produced by combustion and to provide additional mixing of the oxidant with the fuel prior to the dilution zone.

18. The power production plant of claim 17, wherein at least a portion of an outer surface of the combustor liner is configured to receive a flow of any one or more of the fuel, the oxidant, and the diluent thereagainst prior to being received by the combustion chamber to thereby provide for cooling of the combustor liner.

19. The power production plant of claim 17, wherein the combustor liner comprises a plurality of longitudinally-extending reinforcing rib members engaged with the outer surface of the combustor liner, wherein at least a portion of the outer surface of the combustor liner between adjacent reinforcing rib members is configured to receive the flow of any one or more of the fuel, the oxidant, and the diluent thereagainst prior to being received by the combustion chamber.

20. The power production plant of claim 17, wherein the combustor liner comprises one or more openings defined therein and adapted for passage therethrough of the diluent into the combustion chamber.

21. A power production method comprising: gasifying a solid fuel to form a gaseous fuel; injecting the gaseous fuel from the gasifier into a combustor with an oxidant and a diluent so as to combust the fuel and form a combustor exhaust stream; and passing the combustor exhaust stream through a turbine to generate power; wherein the combustor includes an outer casing and a combustor liner defining a combustion chamber therein, and wherein a flow of any one or more of the gaseous fuel, the oxidant, and the diluent is passed along at least a portion of an outer surface of the combustor liner prior to being received by the combustion chamber to thereby provide for cooling of the combustor liner.

22. The power production method of claim 21, wherein the combustor liner comprises a plurality of longitudinally-extending reinforcing rib members engaged with the outer surface of the combustor liner, and wherein the flow of any one or more of the fuel, the oxidant, is passed along at least a portion of the outer surface of the combustor liner between adjacent reinforcing rib members prior to being received by the combustion chamber.

23. The power production method of claim 21, wherein the combustor liner comprises one or more openings defined therein, and wherein at least a portion of the oxidant is passed through the one or more openings into the combustion chamber.

24. The power production method of claim 21, wherein the combustor liner comprises one or more openings defined therein, and wherein at least a portion of the diluent is passed through the one or more openings into the combustion chamber.

25. The power production method of claim 21, comprising passing at least a portion of the oxidant into the combustion chamber through an oxidant injector engaging an upstream end of the combustor liner.

26. The power production method of claim 25, comprising passing a portion of the oxidant into the combustion chamber through a first stage oxidant injector that includes a swirler device that directs the oxidant into the combustion chamber at an angle of about 20 degrees to about 85 degrees relative to axial.

27. The power production method of claim 25, comprising passing the gaseous fuel into the combustion chamber through a fuel nozzle that is engaging a passage through the oxidant injector.

28. The power production method of claim 25, comprising passing a portion of the oxidant into the combustion chamber through a second stage oxidant injector passing through a wall of the combustor liner defining the combustion chamber.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0041] FIG. 1 is an illustration of a power production plant useful for carrying out a power product method according to exemplary embodiments of the present disclosure;

[0042] FIG. 2 is a partial cross-sectional view of a combustor useful in a power production plant and power production method according to exemplary embodiments of the present disclosure;

[0043] FIG. 3A is a perspective illustration of a combustor liner useful in a power production plant and power production method according to exemplary embodiments of the present disclosure;

[0044] FIG. 3B is a partial cross-sectional view of a combustor liner useful in a power production plant and power production method according to exemplary embodiments of the present disclosure;

[0045] FIG. 4 is a partial perspective illustration of a fuel nozzle useful in a power production plant and power production method according to exemplary embodiments of the present disclosure; and

[0046] FIG. 5 is a partial perspective illustration of a swirler device useful in a power production plant and power production method according to exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION

[0047] The present subject matter will now be described more fully hereinafter with reference to exemplary embodiments thereof. These exemplary embodiments are described so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. Indeed, the subject matter can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification, and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise.

[0048] The present disclosure relates to systems and methods adapted for power production utilizing solid fuels such as coal. The solid fuels specifically can be partially oxidized to provide a gaseous fuel, such as synthesis gas (or syngas) that is combusted in a power production plant and process. As such, in some embodiments, the disclosure encompasses coal syngas oxy-combustion in a high pressure supercritical CO.sub.2 environment. The present disclosure therefore encompasses systems and methods wherein coal and another solid hydrocarbon feedstock material can be partially oxidized into a syngas, which can then be fed into a combustor in the oxy-combustion system and method.

[0049] In one or more embodiments, a solid fuel can be partially oxidized to provide a gaseous fuel that is itself combusted in a power production plant and process. As such, as used herein, reference to a “gaseous fuel,” “fuel gas,” or the like is understood to reference a fuel in gas form that is directly derived from the partial oxidation of a solid fuel—e.g, gasification of a solid fuel. The term “syngas” in particular is understood to mean a gas of variable chemistry arising from the partial oxidation of coal. For example, coal and/or another solid feedstock material can partially oxidized in a gasifier to produce high temperature raw syngas, which can contain varying combinations of H.sub.2, CO, CH.sub.4, CO.sub.2, H.sub.2S, and other minor species. Likewise, other solid fuels can be partially oxidized to provide a gaseous fuel. The raw syngas can be further processed, for example, by cooling and cleaning to remove ash, soluble acid(s), water, and heavy metal(s). Sulfur species can be removed by existing acid gas removal process or stay in the syngas for combustion. Existing gasifiers, including entrained flow gasifiers, fluidized bed gasifiers, and moving bed gasifiers can be used for gasification of various coal feedstock or other solid feedstock materials. The cleaned coal syngas chemistry varies by different coal feedstock, different gasifiers, different coal feeding systems, and different syngas cleanup procedures.

[0050] The properties of a syngas fuel, including combustion properties, can differ significantly based upon the actual chemistry of the syngas fuel. For example, syngas fuels that are rich in hydrogen and methane will exhibit fuel properties from syngas fuels that are rich in carbon monoxide. The heating value of syngas is strongly impacted by the CO.sub.2 content in the syngas, and this can differ significantly depending upon the type of coal gasifier that is utilized to produce the syngas. For example, syngas produced from slurry fed gasifiers can have a CO.sub.2 content in excess of 20% by mass, while syngas produced from dry fed gasifiers can typically have a CO.sub.2 content of less than 10% by mass. Therefore, for a given mass of each fuel, properties such as flame characteristics, thermal energy delivered to the downstream system temperature profiles, exhaust gas conditions, and exhaust gas compositions can vary significantly.

[0051] Since a combustor for a power production facility must be designed as a fixed chamber, only a narrow range of fuel mixtures can be matched with the combustor design conditions (and therefore flame and combustor outlet conditions) and thus be tolerable for use in the combustor. Further, mixtures within this range may still cause perturbations in combustor or flame behavior that must be tightly controlled. The present disclosure thus is beneficial in that it can achieve power production utilizing coal or another solid fuel as the initial fuel source by providing partial oxidation followed by combustion of the produced syngas in a combustor that is configured to accommodate the varying chemistries of the produced syngas.

[0052] The present disclosure thus can relate to power production plants and processes including a variety of elements. Non-limiting examples of elements that may be included in power production plants and processes according to the present disclosure are described in U.S. Pat. Nos. 8,776,532, 9,581,082, and U.S. Pat. Pub. No. 2017/0241338, the disclosures of which are incorporated herein by reference.

[0053] A power production plant and methods of operation thereof are further described herein in relation to FIG. 1. As seen therein, the power production plant 100 includes elements suitable for partial oxidation of a solid fuel, such as coal, to form a gaseous fuel that is combusted in a combustor that is configured for continuous operation even when fuels of differing chemistries are utilized. As such, it is possible to utilize solid fuels of different grades that result in formation of gaseous fuels with varying chemistries without need for changing the combustor.

[0054] Referencing FIG. 1, in exemplary embodiments, a power production plant 100 can include an air source 101 that provides air into an air separation unit (ASU) 102 to form a stream of substantially pure oxygen in line 103 and line 104. Although not illustrated, it is understood that the ASU 102 may include a variety of compressors and/or pumps configured to provide the oxygen in lines 103 and 104 at increased pressures (which may differ or be substantially the same). If desired, however, additional compressors and/or pumps may be provided in line 103 and/or line 104 to provide the desired level of compression. The oxygen in line 103 is directed to a gasifier 105, which can be a single gasifier or a plurality of gasifiers, and any suitable type of gasifier as otherwise noted herein may be utilized. Solid fuel from solid fuel source 106 can be provided to a prep station 107 where, for example, the solid fuel may be ground with one or more grinders to provide a particularized solid fuel of the desired average particle size. In the prep station 107, the solid fuel may be entrained in a fluidizing medium, such as substantially pure carbon dioxide (although other fluidizing media may be used in addition or in the alternative). The solid fuel prepared in the prep station 107 is passed through line 108 to the gasifier 105 and exits in line 109 as a partially oxidized, gaseous fuel. For example, when the solid fuel is coal, a synthesis gas (“syngas”) of varying chemistries may be provided through line 109. The gaseous fuel in line 109 is passed through a scrubbing unit 110, which unit can include one or more elements for removing particulates and other non-fuel components of present in the gaseous fuel. The cleaned gaseous fuel is passed in line 111 to a heat exchanger 112, which can be used to provide low grade heating as otherwise described herein. The cooled gaseous fuel exits the heat exchanger in line 113, is compressed in the gaseous fuel compressor 114, and is delivered through line 115 to a combustor 116.

[0055] The gaseous fuel from line 115 is combusted in the combustor 116 with the oxygen from line 104, which optionally may be diluted with a diluent, such as an inert gas, carbon dioxide, or water. Preferably, recycle carbon dioxide in line 155 is also input to the combustor 116. The combustor exhaust stream exits the combustor 116 in line 117 and is expanded in a turbine 118 to generate power with generator 119. The turbine exhaust in line 120 is passed through a heat exchanger 125 where it is cooled and exits in line 126 before passage through a cooler 127 that provides the exhaust stream through line 128 at near ambient temperature to a water separator 130. Water exits the separator 130 in line 132, and the water stream may further include solubilized impurities, such as H.sub.2SO.sub.4 and HNO.sub.3. Substantially pure carbon dioxide exits the separator 130 in line 131, is compressed in compressor 135, passes through line 136 to cooler 137 to increase the density of the carbon dioxide, and exits in line 138. A portion of the carbon dioxide in line 138 can be passed through line 140 to the solid fuel prep station 107 (e.g., to be used as a fluidizing medium). The remainder of the high density carbon dioxide passes in line 139 to pump 145 where it is pumped to a pressure suitable for input to the combustor 116 and exits as line 150. A portion of the high pressure carbon dioxide in line 150 may be exported from the power production plant 100 in line 151. The remaining portion of the substantially pure, high pressure, recycle carbon dioxide from line 150 is directed through line 152 through the heat exchanger 125 to be re-heated against the turbine exhaust in line 120. The heated, recycle carbon dioxide passes in line 155 to the combustor 116.

[0056] In one or more embodiments, the present disclosure particularly provides a combustor (116, 216) that can be configured for combusting a gaseous fuel that is subject to varying chemistries arising from formation of the gaseous fuel through partial oxidation of a solid fuel. As such, the combustor (116, 216) can have a combustion chamber 270 configured to receive a fuel, an oxidant, and a diluent, directly, indirectly, or both directly and indirectly. For example, the fuel, the oxidant, and the diluent can be received into the combustion chamber 270 directly via an injection mechanism or a diffusion mechanism. For example, the fuel, the oxidant, and the diluent can be received into the combustion chamber 270 indirectly by way of a mixing arrangement, wherein the fuel, the oxidant, and the diluent are pre-mixed prior to being introduced into the combustion chamber 270.

[0057] Referring to FIG. 2, the combustion chamber 270 of the combustor 216 can be defined by a combustor liner 260 that is surrounded by an outer casing 265. The outer casing 265 can include one or more cooling elements, such as cooling orifices 282, though which a cooling fluid may be circulated. In some embodiments, the cooling fluid may be the same material as used for the diluent as further discussed herein. At least a portion of an outer surface of the combustor liner 260 can be configured to receive a flow of any one or more of the fuel, the oxidant, and the diluent thereagainst prior to any one or more of the fuel, the oxidant, or the diluent being directed into the combustion chamber 270 to thereby provide for cooling of the combustor liner. In some embodiments, the outer surface of the combustor liner 260 can include a periphery and a length, and substantially the entirety of the outer surface of the combustor liner, about the periphery and along the length thereof, can be configured to receive the flow of any one or more of the fuel, the oxidant, or the diluent thereagainst prior to any one or more of the fuel, the oxidant, or the diluent being directed into the combustion chamber 270.

[0058] Backside wall cooling or outer wall surface cooling can be beneficial, in some embodiments, to keep operational temperatures of the combustor liner 260 below a particular threshold. This can be achieved in some instances by flowing supercritical carbon dioxide (“sCO.sub.2”), oxidant, and/or fuel flow along a length of the combustor liner prior to supplying the sCO.sub.2, oxidant and/or fuel to the combustor. High pressure sCO.sub.2 has a high specific heat value, which may reduce the amount of sCO.sub.2 required for the effectively cooling the combustor liner 260 compared to other types of cooling gases.

[0059] In addition to the foregoing (or in the alternative), the sCO.sub.2 cooling the combustor liner 260 can be subsequently directed (“recycled”) to other processes associated with the power system implementing such a combustor. In this manner, energy loss through the combustor wall and/or liner can be reduced, and the combustion cycle efficiency can be improved.

[0060] In the exemplary embodiments illustrated in FIG. 2, the combustor liner 260 includes a plurality of perforations 261 so that injected fluid flowing along the outer periphery of the combustor liner may pass therethrough into the combustion chamber 270. The combustion chamber 270 can be divided into a reaction zone 271 and a dilution zone 273. The reaction zone (RZ) 271 can be the portion of the combustion chamber 270 proximate the fuel nozzle 280—i.e., at the front, or upstream portion of the combustion chamber. The dilution zone (DZ) 273 can be proximate the exit 291 of the combustion chamber 270—i.e., at the end or downstream portion of the combustion chamber. In some embodiments, the reaction zone 271 and the dilution zone 273 can each encompass approximately half of the total volume of the combustion chamber 270. A volume ratio (RZ/DZ) of the combustion chamber 270 encompassed by the reaction zone 271 relative to the dilution zone 273 can be about 0.1 to about 5, about 0.25 to about 4, about 0.5 to about 2, or about 0.75 to about 1.5.

[0061] For combustion, fuel gas enters in line 215 to pass through the fuel nozzle 280 into the combustion chamber 270, and particularly the reaction zone 271. The fuel gas in line 215 can be diluted through addition of diluent through line 255a. The diluent may be, for example, an inert gas, carbon dioxide, water, or a mixture thereof. The fuel nozzle 280 can include a cone 281a with a plurality of perforations 281b. The perforations 281b in the cone 281a can be aligned at a defined angle from the axial (e.g., about 15 degrees to about 80 degrees, about 20 degrees to about 70 degrees, about 25 degrees to about 60 degrees, or about 30 degrees to about 50 degrees from the axial) to distribute the fuel through the reaction zone 271 as the fuel mixes with the oxidizer and burns. Oxidant in line 204 enters the oxidant injector 285, which includes a first stage oxidant injector 285a and a second stage oxidant injector 285b. Oxidant in the first stage oxidant injector 285a can enter the combustion chamber 270 substantially co-linear with the fuel gas entering through the fuel nozzle 280. As further described below, the first stage oxidant injector 285a can be substantially configured to impart a defined directional flow to the oxidant, such as providing a swirling flow within the combustion chamber 270, particularly within the reaction zone 271. Although two openings are illustrated in FIG. 2 defining the first stage oxidant injector 285a, it is understood that the first stage oxidant injector 285a may substantially surround the fuel nozzle 280 and thus define a plurality of openings for oxidant injection—e.g., at least 2, at least 3, at least 4, at least 5, at least 6, or even more openings (such as 2 to 20, 3 to 16, or 4 to 12 openings). The second stage oxidant injector 285b can comprise one or more perforations or other portals configured through the combustor liner 260. As such, the oxidant can pass around a portion of the outer periphery of the combustor liner 260, particularly around a portion of the outer periphery of the combustor liner that is at least partially defining the reaction zone 271 within the combustion chamber 270. Oxidant entering the combustion chamber 270 through the second stage oxidant injector 285b can be injected substantially perpendicularly to the flow of the oxidant entering through the first stage oxidant injector 285a. Again, although four openings are illustrated in FIG. 2 defining the second stage oxidant injector 285b, it is understood that the second stage oxidant injector 285b may substantially surround the a portion of the combustor chamber 270 and thus define a plurality of openings for oxidant injection through the combustor liner 260—e.g., at least 2, at least 3, at least 4, at least 5, at least 6, or even more openings (such as 2 to 20, 3 to 16, or 4 to 12 openings). The openings defining the second stage oxidant injector 285b may be longitudinally spaced along a portion of the combustor liner 260 as illustrated. In some embodiments, the openings defining the second stage oxidant injector 285b may be aligned in a single row around the outer periphery of the combustor liner 260 or may be aligned in a plurality of rows around the outer periphery of the combustor liner. The oxidant in line 204 can be diluted through addition of diluent through line 255b. The diluent may be, for example, an inert gas, carbon dioxide, water, or a mixture thereof. At the inlet to the combustion chamber 270, the combustor liner 260 fits over the oxidant injector 285 to provide radial support while also allowing for axial, thermal growth. The periphery of the combustor liner 260 is configured to manage the cooling flow used for cooling the liner and managing the second stage oxidizer supply.

[0062] A diluent stream 255c may be passed directly into the combustion chamber 270 through the combustor liner 260 in one or more embodiments. The diluent stream 255c thus may be injected around at least a portion of the outer periphery of the combustor liner 260 for passage through the perforations 261 or other openings into the combustion chamber 270. The diluent stream 255c can particularly be injected into the dilution zone 273.

[0063] The combustor liner 260 is further illustrated in FIG. 3a and FIG. 3b. In one or more embodiments, the combustor liner 260 can be configured to include a plurality of longitudinally-extending reinforcing members engaged with the outer surface of the combustor liner, wherein at least a portion of the outer surface of the combustor liner between adjacent reinforcing members is configured to receive a flow of any one or more of the fuel, the oxidant, or the diluent thereagainst prior to any one or more of the fuel, the oxidant, or the diluent being directed into the combustion chamber. As illustrated, the outer surface 260a of the combustor liner 260 includes a plurality of ribs 263 extending outward from the outer surface of the combustor liner, and a plurality of cooling channels 264 are defined by adjacent ribs and the outer surface of the combustor liner. At least a portion of the second stage oxidant injector 285b can be defined in the combustor liner 260 in the form of a plurality of oxidant ports 285b′ that extend outward from the combustor liner. The oxidant for injection through the second stage oxidant injector 285b can thus flow along at least a portion of the combustor liner 260 in the channels 264 between the ribs 263 to provide for backside cooling of the combustor liner prior to injection into the combustion chamber 270. As illustrated, the oxidant ports 285b′ forming the second stage oxidant injector 285b are radially aligned around the outer periphery of the combustor liner 260 in a single array. It is understood, however, that different alignments are also encompassed. For example, a plurality of arrays may be utilized. Moreover, a random spacing may be utilized.

[0064] In addition to the foregoing, a plurality of diluent ports 261′ may be included in the combustor liner 260, the diluent ports extending outward from the outer surface 260a of the combustor liner. The diluent ports 261′ are positioned downstream relative to the oxidant ports 285b′. As such, the oxidant ports 285b′ may be substantially positionally aligned with the reaction zone 271 within the combustion chamber 270, and the diluent ports 261′ may be substantially positionally aligned with the dilution zone 273 of the combustion chamber. The diluent for injection into the combustion chamber 270 can thus flow along at least a portion of the combustor liner 260 in the channels 264 between the ribs 263 to provide for backside cooling of the combustor liner prior to injection into the combustion chamber. As illustrated, the diluent ports 261′ are radially aligned around the outer periphery of the combustor liner 260 in a plurality arrays. It is understood, however, that different alignments are also encompassed. For example, a single array or a greater number of arrays may be utilized. Moreover, a random spacing may be utilized.

[0065] The combustor liner 260 and/or the outer casing 265 of the combustor 216 may include additional structural elements as needed. For example, in order to separate the cooling flows provided by the oxidant and the diluent along the outer periphery of the combustor liner 260, a separating wall 293 may be included between the oxidant ports 285b′ and the diluent ports 261′ so that only oxidant may flow along the upstream portion of the combustor liner 261 and only diluent may flow along the downstream portion of the combustor liner 261. In some embodiments, the combustor line can comprise a plurality of layers. For example, as seen in FIG. 3a, a first, inner layer 260′ of the combustor liner 260 extends outward from the upstream end 260c of the combustor liner. The first layer 260′ thus may engage the oxidant injector 285 as otherwise described herein. Oxidant may be passed along the outer periphery of the combustor liner 260 for passage into the oxidant port 285b′. Diluent may be passed in a space 266 between the first layer 260′ and a second, outer layer 260″. The ribs 263 and channels 264 may thus be defined in the second, outer layer 260″ of the combustor liner 260. The diluent may exit the downstream end 260d of the combustor liner 260 and circulate outward to the outer periphery of the combustor line to flow back and into the diluent ports 261′.

[0066] In yet further embodiments, as seen in FIG. 3b, a sleeve member 267 can extend about the outer surface of the combustor liner 260 and the plurality of reinforcing ribs 263. The sleeve member 267 can cooperate with at least the ribs 263 to define the plurality of longitudinally-extending cooling channels 264 about the outer surface of the combustion chamber 270. The flow of any one or more of the fuel, the oxidant, or the diluent can be directed through the cooling channels 264 and against the outside surface 260a of the combustor liner 260 prior to any one or more of the fuel, the oxidant, or the diluent being directed into the combustion chamber 270. In some embodiments, supercritical carbon dioxide (sCO.sub.2) may particularly be used as the diluent that is directed to flow along the channels. This sCO.sub.2 cooling flow along the channels provides, for example, backside or outer surface convective cooling of the combustor liner, which facilitates maintaining the combustor liner below material temperature limitations.

[0067] In operation, the same fuel nozzle 280 and oxidant injector 285 can be utilized with varying fuel chemistries by adjusting the oxidant to diluent ratio and/or the fuel to diluent ratio.

[0068] This can be achieved by varying the ratios in the injected streams and/or by varying the amount of diluent that is added directly to the combustion chamber 270 in the diluent stream 255c. The combustion reaction can be completed in a substantially uniform temperature range (e.g., about 1,200° C. to about 3,000° C., about 1,400° C. to about 2,800° C., or about 1,600° C. to about 2,400° C.) in the reaction zone to form a combustor exhaust stream 299 that is cooled in the dilution zone 273 to a near uniform temperature range (e.g., about 600° C. to about 1,500° C., about 800° C. to about 1,400° C., or about 900° C. to about 1,200° C.). The combustor 216 is preferably sized to accommodate the required heat release rate, flow rates, and residence times to produce well mixed turbine inlet flows with complete combustion, the combustor exhaust comprising being carbon dioxide rich.

[0069] In one or more embodiments, the first stage oxidant injector 285a can be configured to introduce a first portion of the oxidant from line 204 (optionally include diluent from line 255b) into the reaction zone 271 of the combustion chamber 270 through a swirler device. In an exemplary embodiments illustrated in FIG. 2, a swirl plate 286 can be included with the oxidant injector 285 and preferably is positioned at the outlet of the oxidant injector into the combustion chamber 270. The swirl plate 286 can comprise a central orifice 286a through which the fuel nozzle 280 may extend. As such, the central orifice 286a can have in internal diameter that is substantially identical to an external diameter of the fuel nozzle 280, although the relative dimensions may vary as needed to accommodate additional components, such as a sealing arrangement that may be provided between the fuel nozzle and the swirl plate as desired. The swirl plate 286 further includes a plurality of oxidant vents 286b—i.e., openings in the swirl plate to allow flow of oxidant from the oxidant injector 285 to pass therethrough. As illustrated, by including the swirl plate 286, the first stage oxidant injector 285a may substantially surround the fuel nozzle 280 and thus define a plurality of openings for oxidant injection—e.g., at least 2, at least 3, at least 4, at least 5, at least 6, or even more openings (such as 2 to 20, 3 to 16, or 4 to 12 openings). The oxidant vents 286b in the swirl plate 286 preferably are angularly aligned to direct the oxidant into the combustion chamber 270 at an angle relative to axial. In some embodiments, the angular alignment can be configured to produce a desired swirl number. For example, the oxidant vents 286b can be angularly aligned to direct oxidizer into the combustion chamber at an angle relative to axial that is in the range of about 20 degrees to about 85 degrees, about 30 degrees to about 80 degrees, about 40 degrees to about 75 degrees, or about 50 degrees to about 70 degrees. The angular alignment can be configured to provide an effective swirl number of about 1 to about 10, about 1.1 to about 5, or about 1.2 to about 2.

[0070] The swirler device utilized in the first stage oxidant injector 285a preferably is configured to provide for mixing of the oxidant with the fuel so as to produce recirculation within the reaction zone 271 about a center axis to induce a flame-stabilizing vortex breakdown and to enhance mixing. The second stage oxidant injector 285b can be configured to introduce a second portion of the oxidant (optionally including diluent) into the combustion chamber 270 through the combustor liner 260. The injection of the oxidant through the second stage oxidant injector 285b preferably is provided downstream of the first stage oxidant injector 285a but still positioned to introduce the oxidant into the reaction zone 271 of the combustion chamber 270 (i.e., upstream from the dilution zone 273). The second stage oxidant injector 285b can be configured to stabilize a flame produced by combustion and provide additional mixing of the oxidant with the fuel upstream from the dilution zone 273. The mass flow of the oxidant (optionally including a diluent) through the first stage oxidant injector 285a and the second stage oxidant injector 285b can vary and may be adjustable in response to changes in the fuel chemistry. The mass flow ratio of the first stage oxidant injector 285a to the second stage oxidant injector 285b can be about 0.1 to about 8, about 0.25 to about 5, about 0.5 to about 2, or about 0.75 to about 1.5. The mass ratio of the first stage oxidant injector 285a to the second stage oxidant injector 285b can be tuned to provide efficient fuel/oxidant mixing and a complete fuel burnout of the fuel, oxidant, and diluent fuel mixture.

[0071] Many modifications and other embodiments of the presently disclosed subject matter will come to mind to one skilled in the art to which this subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the present disclosure is not to be limited to the specific embodiments described herein and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.