BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to gasification and combustors. More particularly  the subject disclosure relates to injector nozzles for gasification.
[0002] Many known integrated gasification combined-cycle (IGCC) plants include a gasification system that is integrated with at least one power-producing turbine system. For example  at least some known gasification systems convert a mixture of fuel  air or oxygen  steam  and/or CO2 into a synthetic gas  or “syngas”. The sysngas is channeled to the combustor of a gas turbine engine  which powers an electrical generator that supplies electrical power to a power grid. Exhaust from at least some known gas turbine engines is supplied to a heat recovery steam generator (HRSG) that generates steam for driving a steam turbine. Power generated by the steam turbine also drives an electrical generator that provides electrical power to the power grid.
[0003] At least some gasification systems include an injection system that supplies a gasifier reactor with process fluids to facilitate at least one exothermic reaction. Some gasification systems use multiple types of fuel to drive the gasification process. For example  a coal gasification plant primarily utilizes a coal slurry as fuel to drive gasification which converts the carbon in the coal into a gaseous fuel to produce electricity. When the gasifier is initialized  however  the system components downstream of the gasification chamber are not yet at a design point operating pressure  so the process efficiency is lacking. Thus  gasification of the coal slurry produces a higher amount of undesirable emissions such as sulfur and/or NOx until the downstream components are brought up to pressure.
[0004] In an attempt to alleviate these emissions issues  cleaner burning fuels  such as natural gas are often introduced into the gasification chamber during startup in place of the coal slurry. The natural gas is injected into the gasifier via a dedicated nozzle separate from that of the coal slurry.
BRIEF DESCRIPTION OF THE INVENTION
[0005] According to one aspect of the invention  an injector tip for a gasifier combustor nozzle includes a center body having a plurality of center body openings at a distal end configured to inject a fuel flow into a combustion zone of the combustor. One or more fuel passages are arranged around the center body and are configured to inject a fuel slurry into the combustion zone. One or more oxygen passages are arranged around the center body and are configured to inject an oxygen flow into the combustion zone.
[0006] According to another aspect of the invention  a method of fuel injection into a combustor includes injecting a first portion of a fuel flow into a combustion zone of the combustor through a plurality of center body openings in a distal end of a center body of an injector tip. A second portion of the fuel flow is injected into the combustion zone via one or more fuel passages arranged around the center body. The injection of the second portion of the fuel flow is suspended and a fuel slurry is injected into the combustion zone via one or more fuel passages.
[0007] These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] 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:
[0009] FIG. 1 is a schematic cross-sectional view of an embodiment of an injector tip for a gasifier nozzle;
[0010] FIG. 2 is a schematic of operation of an embodiment of an injector tip for a gasifier nozzle during startup operation; and
[0011] FIG. 3 is a schematic of operation of an embodiment of an injector tip for a gasifier nozzle during coal slurry operation.
[0012] The detailed description explains embodiments of the invention  together with advantages and features  by way of example with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Shown in FIG. 1 is an embodiment of an injection nozzle tip 10 for a gasifier. The nozzle tip 10 of the embodiment of FIG. 1 includes four separate and distinct channels for flow of streams of materials through the nozzle tip 10. First  the nozzle tip 10 includes a center body 12 which is  in some embodiments  located at a central axis 14 of the nozzle tip 10. The center body 12 includes a plurality of center body openings 16 located at a distal end 18 of the center body 12.
[0014] A plurality of fuel passages  or lances  are arranged surrounding the center body 12. An inner passage 20 is located around the center body 12  and in some embodiments is concentric with the center body 12. A middle passage 22 is located around the center body 12 outboard of the inner passage 20  and in some embodiments is concentric with the center body 12 and/or the inner passage 20. As shown in FIG. 1  an outer passage 24 is located around the center body 12 outboard of the middle passage 22  and in some embodiments is concentric with the center body 12  the inner passage 20 and/or the middle passage 22. In some embodiments  an inner passage end 26  a middle passage end 28  and/or an outer passage end 30 are flush with the distal end 18 of the center body 12.
[0015] At startup of the gasifier  as shown in FIG. 2  a fuel flow 32  for example  a low-sulfur fuel such as natural gas  is injected into a combustion zone 34 downstream of the nozzle tip 10 through the center body 12 via the center body openings 16. The fuel flow 32 of the low sulfur fuel is also injected into the combustion zone 34 through the middle passage 22. A flow of primary oxygen 36 is provided to the combustion zone 34 through the outer passage 24. The primary oxygen 36 is mixed with the fuel flow 32 in the combustion zone 34 and combusted therein. In some embodiments  a flow of secondary oxygen 38 may be injected into the combustion zone 34 through the inner passage 20 to provide further oxygen for combustion with the fuel flow 32.
[0016] Referring now to FIG. 3  during coal slurry mode operation of the gasifier  middle passage 22 is utilized to convey a flow of gasifier fuel  such as coal slurry 40 into the combustion zone 34. Primary oxygen 36 and secondary oxygen 38 are provided through the outer passage 24 and the inner passage 20  respectively. Since  during normal operation  the flow of coal slurry 40 drives the gasification process  the fuel flow 32 through the center body 12 is stopped  and a flow of a different fluid 42  such as carbon dioxide (which may be recycled)  nitrogen  steam  or water  is flowed through the center body openings 16. The fluid 42 can be purge gas  moderator gas or cooling liquid. The fluid 42 provides cooling to the center body 12  and also prevents plugging of the center body openings 16 with particulates from the combustion of the coal slurry 40. Further  the fluid 42 prevents burnbacks  combustion products backing upstream through the center body openings 16  in the center body 12.
[0017] During transitions in operation from  for example  startup operation and coal slurry mode operation  both fuel flow 32 and coal slurry 40 may be injected into the combustion zone 34  with the fuel flow 32 injected through the center body openings 16 and the coal slurry 40 injected through the middle passage 22. As the transition occurs from startup (all fuel flow 32) to coal slurry mode (all coal slurry 40)  an amount of each flow can be gradually changed to provide a smooth transition between the two modes. For example  as the operation moves from startup to coal slurry mode  the amount of fuel flow 32 injected through the center body openings 16 is gradually decreased while the amount of coal slurry 40 injected through the middle passage 22 is gradually increased. Further  switching between coal slurry mode and a standby mode  where the flow of coal slurry 40 is stopped and injection of the fuel flow 32 is resumed  can occur quickly since the nozzle tip 10 has the ability to inject either or both types of fuel via the separate center body 12 and middle passage 22.
[0018] In some embodiments  the inner tip end 26  the middle passage end 28  and/or the outer passage end 30 are flush with the distal end 18 of the center body 12. Having the ends all flush with each other prevents premixing of the fuels with the primary oxygen  which may be detrimental to performance of the gasifier. Further  the flush end configuration prevents burnback during coal slurry mode operation.
[0019] 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.

WHAT IS CLAIMED IS:
1. An injector tip (10) for a nozzle comprising:
a center body (12) having a plurality of center body openings (16) at a distal end (18) configured to inject a fuel flow (32) into a combustion zone (34) of a combustor;
one or more fuel passages (20 22 24) arranged around the center body (12) configured to inject a fuel slurry into the combustion zone (34); and
one or more oxygen passages (20 22 24) arranged around the center body (12) to inject an oxygen flow into the combustion zone (34).
2. The injector tip (10) of Claim 1  wherein at least one of the one or more fuel passages (20 22 24) or at least one of the one or more oxygen passages are substantially concentric with the center body (12).
3. The injector tip (10) of Claim 1  wherein at least one of the one or more fuel passages (20 22 24) or at least one of the one or more oxygen passages (20 22 24) are substantially flush with the distal end (18) of the center body (12).
4. The injector tip (10) of Claim 1  wherein the center body (12) is further configured to inject a purge fluid into the combustion zone (34).
5. The injector tip (10) of Claim 1  wherein the one or more fuel passages (20 22 24) are further configured to inject a fuel flow and/or a mixture of fuel flow (32) and fuel slurry into the combustion zone (34).
6. A method of fuel injection into a combustor comprising:
injecting a first portion of a fuel flow (32) into a combustion zone (34) of the combustor through a plurality of center body (12) openings in a distal end (18)of a center body (12) of an injector tip (10);
injecting a second portion of the fuel flow (32) into the combustion zone (34) via one or more fuel passages (20 22 24) arranged around the center body (12); and
suspending the injection of the second portion of the fuel flow (32); and
injecting a fuel slurry into the combustion zone (34) via one or more fuel passages (20 22 24).
7. The method of Claim 6  further comprising:
suspending the injection of the first portion of the fuel flow (32); and
injecting a fluid into the combustion zone (34) via the plurality of center body openings (16).
8. The method of Claim 6  wherein injecting the second portion of the fuel flow (32) and injecting the fuel slurry comprise simultaneously injecting the second portion of the fuel flow (32) and injecting the fuel slurry into the combustion zone (34) via the one or more fuel passages (20 22 24).
9. The method of Claim 6  wherein injecting the fuel slurry comprises injecting a coal slurry (40).
10. The method of Claim 6  further comprising injecting a flow of oxygen into the combustion zone (34) via one or more oxygen passages arranged around the center body (12).
Dated this the 26th Day of May  2012

MANISHA SINGH NAIR
Agent for the Applicant [IN/PA-740]
LEX ORBIS IP PRACTICE
INJECTOR TIP ASSEMBLY AND METHOD OF FUEL INJECTION

ABSTRACT
An injector tip for a nozzle (10) includes a center body (12) having a plurality of center body openings (16) at a distal end (18) configured to inject a fuel flow (32) into a combustion zone (34) of a combustor. One or more fuel passages (20  22  24) are arranged around the center body (12) and are configured to inject a fuel slurry into the combustion zone (34). One or more oxygen passages (20  22  24) are arranged around the center body (12) and are configured to inject an oxygen flow (36) into the combustion zone (34).