Fuel splashplate for microturbine combustor

Abstract

A splashplate dish or disc shaped having a contoured face is inserted in and recessed from the top of the air tube feeding the combustor of a microturbine with a mixture of air and fuel. The splashplate permits the use of a single orifice fuel nozzle or injector to replace a multi orifice injector. The splashplate includes contoured segments circumferentially disposed around the face of the splashplate for splitting the fuel into discrete streams for mixing with the air admitted into the air tube. In one embodiment the splashplate includes radial slots circumferentially spaced around the face of the splashplate for directing the fuel directly into the air tube through the slots. In another embodiment a dimple or depression is located centrally of the splashplate where the fuel impinges before being dispersed in the plurality of streams. Attachment means are provided for centering and recessing the splashplate in the air tube.

Description

TECHNICAL FIELD

[0001] This invention relates to fuel nozzles for gas turbine engines and particularly to the fuel nozzle/air tube for the combustor of a microturbine.

BACKGROUND OF THE INVENTION

[0002] The microturbine is essentially a miniaturized gas turbine engine typically utilized for powering electrical generators. In certain configurations, the turbine and compressor are attached back-to-back on one end of a shaft that is common to the shaft connecting the armature of the electrical generator. Fuel and relatively hot pressurized air discharging from the compressor and recuperator are fed to an annular combustor where they are combined and combusted to further heat and accelerate the engine's working medium for powering the turbine. The engine working medium is adiabatically expanded in the turbine for extracting energy which, in turn, is utilized for rotating the compressor and armature. The working medium after leaving the turbine is directed to the recuperator where it is placed in indirect heat exchange with the compressor discharge air prior to being admitted into the combustor. The turbine exhaust is ultimately discharged from the recuperator. For further details of the microturbine reference should be made to co-pending patent application Ser. No. 09/934,640 filed on Aug. 22, 2001 by William R. Ryan entitled RECUPERATOR FOR USE WITH TURBINE/TURBO-ALTERNATOR, published and U.S. Pat. No. 6,314,717 granted to Teets et al on Nov. 13, 2001 entitled ELECTRICITY GENERATING SYSTEM HAVING AN ANNULAR COMBUSTOR both of which are commonly assigned to the assignee of this patent application, and both being incorporated by reference herein. Also, for more details of this invention reference should also be made to the microturbines manufactured by the assignee, Elliott Energy Systems, Inc., of Stuart, Fla. and, particularly of the types exemplified by Model Number TA-80.

[0003] A continuing effort is being made by scientist and engineers to improve on the efficiency of the microturbine engine from a standpoint of the quality of the emissions exhausting from the engine, the efficiency of the engine, the cost of manufacturing, and the maintenance thereof. To this end, it is contemplated that the burning efficiency, the quality of exhaust and costs can be improved by providing a splashplate judiciously located in the air tube associated with the fuel injector of the combustor. In accordance with this invention, the splashplate permits the use of a single orifice fuel injector and hence, eliminates the multiple orifices fuel injectors. Since the area of the orifice of the single orifice injector is larger than the area of the orifice of the multiple orifice injector, the likelihood of clogging owing to adhesion of foreign matter at the discharge orifice is minimized, if not eliminated. The use of the splashplate that creates the discrete streams of fuel for enhanced mixing affords the benefit of improved burning efficiency and lower maintenance. Because the splashplate of this invention replaces the multiple orifices in the fuel nozzle with a single orifice, lower manufacturing costs are achievable in addition to avoiding, if not eliminating, clogging of the discharge orifice. The invention contemplates shaping the aft end of the splashplate to avoid recirculation of the fuel/air mixture at inappropriate locations and hence, avoiding flaming at undesirable locations.

SUMMARY OF THE INVENTION

[0004] An object of this invention is to provide for the fuel injection system of the combustor of a microturbine engine a splashplate judiciously located in the air tube.

[0005] A feature of this invention is the provision of the splashplate as described mounted in the air tube wherein the face of the splashplate is formed in concaved/convex segments circumferentially formed therein to discretely form fuel streams to effectively mix with the air in the air tube.

[0006] Another feature of this invention is the provision of the splashplate as described wherein the face of the splashplate is formed with a central depression and the contoured segments circumferentially radiate therefrom.

[0007] Another feature of this invention is the configuration of the aft end of the splashplate to minimize or eliminate the occurrence of recirculation zones immediately downstream thereof.

[0008] Another feature of this invention is a splashplate as described including a plurality of radially extending slots circumferentially spaced therein for admitting the fuel impinging on the splashplate to mix with the air in the air tube.

[0009] Another feature of this invention is the attachment and centering mechanism for the splashplate of this invention wherein in one embodiment the attachment interconnects the fuel nozzle and splashplate for centering the splashplate relative to the fuel nozzle.

[0010] The foregoing and other features of the present invention will become more apparent from the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a perspective view of the annular combustion liner and the a partial showing of the fuel manifold of this invention with the splashplate out of view;

[0012] FIG. 2 is an end plan view illustrating the splashplate of this invention mounted to the air tube;

[0013] FIG. 3 is a view partly in schematic and partly in section taken along lines 3-3 of FIG. 2;

[0014] FIG. 4 is a partial view in perspective illustrating another embodiment of this invention;

[0015] FIG. 5 is a partial view in perspective illustrating another embodiment of this invention;

[0016] FIG. 6 is a partial view in perspective illustrating another embodiment of this invention;

[0017] FIG. 7 is a view in section taken along lines 7-7 of FIG. 6;

[0018] FIG. 8 is a sectional view illustrating a modification of this invention with a configured aft section for preventing localized recirculation; and

[0019] FIG. 9 is a schematic view illustrating an option for attaching the splashplate.

[0020] These figures merely serve to further clarify and illustrate the present invention and are not intended to limit the scope thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0021] While splashplates and buffer zones have been utilized in rocket engines and in gas turbine engines, the use of a splashplate in an air tube is an entirely different application for splashplates. In this invention, the splashplate is utilized to eliminate the multi-port fuel injectors and replace them with a single hole fuel injector. Since the same fuel flow is required in both the single and multi-holed injector, the cross sectional area of the single hole is substantially equal to the total cross sectional areas of the multi-port injectors, thus minimizing, if not eliminating, the potential of clogging the port. Moreover, the splashplate of this invention is an alternative method of assuring the creation of smaller particle sizes for enhanced mixing that is necessary for efficient burning. Heretofore, the fuel injector for the combustor of a microturbine utilized three holes so as to obtain the desired particle sizes in the streams of fuel. In the microturbine that utilizes gaseous fuel, the injector included three holes to produce three streams of gaseous fuel that is injected into the combustion zone. Obviously, the manufacturing costs for making a three ported injector is significantly more expensive than a single ported injector. The invention contemplates the use of liquid fuel as well as gaseous fuel.

[0022] To best appreciate this invention, reference will be made to FIG. 1 which illustrates the annular combustion liner generally illustrated by reference numeral 10 having an outer liner 12 and an inner liner 14 that is closed on one end at 16 and is opened on the opposite end and the outer and inner liner define an annular combustor passage where fuel/air (fuel can be either liquid or gas) is ignited and combusted to generate the working fluid for the engine. The working fluid discharges from the aft end 18 of the combustor 20 and flows into the turbine (not shown) for generating the power of the engine. A plurality of fuel injectors 20 fluidly connected to the fuel manifold 22 which is connected to a source of fuel (not shown) feed the circumferentially spaced primary air tubes 24. This particular combustor liner includes a dam defining the primary and secondary combustion zones and a plurality of vanes 26 connected to the dam for admitting air into the combustion zone and a plurality of circumferentially spaced combustion or dilution holes 28 for admitting air into the combustion zone. These elements are well known and do not constitute this invention. This invention modifies these existing components by including the splashplate that will be described immediately hereinbelow. For further details of the microturbine and the annular combustion liner reference should be made to U.S. patent application Ser. No. 06/165,876 filed on Jun. 10, 2002 by William F. Beacom entitled Vane and Method of Construction Thereof and commonly assigned to this assignee.

[0023] FIGS. 2 through 5 disclose a plurality of splashplates having different configuration and it is to be understood by those skilled in this technology that configurations can take many forms so long as the fuel injected thereon is divided into separate streams that discharge into the air tube. In each of the embodiments of the splashplates depicted in FIGS. 2 through 5, the splashplates 30, 32 and 34, respectively, are stamped out of sheet metal and are generally circular in shape whose diameter is less than the inside diameter of the air tube 36. (Similar elements have the same reference numerals in all of the Figs.). The fuel injector 38 directs fuel to impinge on the central portion of the splashplates 30, 32 and 34, respectively. In each of the splashplates the fuel is split up into different streams formed around the circumference of the respective splashplate and discharge into the air tube and mixed with the air flowing into the air tube directly into the combustion zone. The splashplates 30, 32 and 34 are configured differently and the face of each of the splashplates are wave-shaped (concave and convex) to define equal segments around the circumference for defining troughs or channels for defining separate streams of fuel. In FIG. 2 the splashplate 30 included a central depression or recess surface 40 and is formed adjacent to the plurality of circumferentially spaced troughs 42. The splashplate depicted in FIG. 4 includes a raised center portion 44 and similarly to FIG. 2 includes a plurality of circumferentially spaced segments that include troughs 46. FIG. 5 is configured similar to FIG. 4 where the raised central portion 48 is dimpled to define a depressed center 50 and the troughs 52 radiate off of this depressed center 50. The splashplates 30, 32 and 34 are mounted in place by a plurality (three in this instance) of inwardly bent and circumferentially spaced tabs 54 that fit into a complementary recess 56 formed on the fore edge 58 of the air tube 36 and secured thereby by suitable welds. It will be appreciated from the foregoing that the tabs 54 are angled so as to recess the respective splashplates into the air tube. Hence, the fuel impinging on the splashplate will not inadvertently spill overboard rather than flow directly into the combustion chamber.

[0024] The splashplate 60 depicted in FIG. 6 is formed from a metallic blank and includes a plurality of slots 62 circumferentially spaced in the segments of the circle and radiate from a central depression 64. The multi-streams of fuel formed by virtue of the impingement on the splashplate flow into the slots 62 where it mixes with the air in the air tube prior to being admitted into the combustion chamber. The aft end 61 of splashplate 60 is dome shaped and this shape serves to prevent the fuel/air mixture forming a localized recirculation zone adjacent to the aft end of the splashplate. Spaced tabs 63 (three are shown) extend from the periphery of the splashplate 60 and fit into complementary slots 69 formed on the top edge 65 of the air tube 67 for supporting the splashplate 60. The tabs 63 may be affixed by a suitable means such as weld or braze. This configuration as well as the one to be described in connection with FIG. 8 can be applied to all the other configured splashplates where it is found that localized recirculation is a problem. FIG. 8 is included to show that other configurations such as the cone shape aft end 71 can be employed with any of the splashplates.

[0025] The structure in FIG. 9 illustrates the option of attaching the splashplate to the fuel nozzle 72. In this instance the splashplate 70 includes three elongated brackets 76 (two being shown) that are welded to the outer periphery of the splashplate 70 at equal circumferential spaces and are bent over the fore shoulder 74 of the fuel nozzle 72 and are welded or attached by any other suitable means to the body of nozzle 72. This attachment means assures that the splashplate is oriented with respect to the discharge port or orifice of the fuel nozzle and that it is centered relative thereto and the air tube. Obviously, the fuel nozzle or injector needs to be removed before removing the liner when it is necessary to repair or overhaul the combustor.

[0026] What has been shown by this invention is a relatively inexpensive way to enhance the fuel delivery to a combustion section by eliminating the heretofore triple orifice injector and replacing it with a single orifice injector. The wavy or grooved shape of the various configured splashplates divides the fuel into multiple smaller streams for effectively mixing with the air in the air tubes before delivery into the combustion zone. Also, effective means are disclosed to eliminate or prevent recirculation zones localizing adjacent to the aft end of the splashplate. The invention is characterized by efficacious mixing while eliminating the more expensive multi-orifice fuel injector.

[0027] Although this invention has been shown and described with respect to detailed embodiments thereof, it will be appreciated and understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.

Claims

1. For the combustor of a microturbine engine including a plurality of air tubes feeding air into the combustion zone of the combustor, at least one splashplate mounted in one of said air tubes, said splashplate being circular in shape, at least one fuel nozzle for feeding fuel into said one air tube, said splashplate having a peripheral edge that is smaller in diameter than the diameter of said one air tube, said fuel nozzle directing the flow of fuel discharging therefrom to impinge on said splashplate, said splashplate having a forward facing face defining a particular configuration whereby the fuel impinging on said splashplate is broken up into discrete streams of fuel by said particular configuration on the face of said splashplate and fed into said one air tube to mix with the air in said one air tube prior to being admitted into the combustion zone.

2. For the combustor of a microturbine engine as claimed in claim 1 including a plurality of tabs having one end attached to said splashplate and another end attached to said one air tube supporting said splashplate in said one air tube and recessed from the end of said one air tube.

3. For the combustor of a microturbine engine as claimed in claim 1 including a bracket interconnecting said splashplate and said fuel nozzle for supporting said splashplate in said one air tube and said splashplate being recessed in said one air tube whereby said splashplate is centered relative to the fuel discharging from said fuel nozzle.

4. For the combustor of a microturbine engine as claimed in claim 1 including a plurality of circumferentially spaced radial slots formed in said one splashplate.

5. A plurality of circular shaped splashplates for the combustor of a microturbine engine in combination with a plurality of air tubes circumferentially mounted about the combustor for feeding air into the combustion zone of the combustor, each of said splashplates mounted in each of said air tubes, a plurality of fuel nozzles complementing the number of air tubes for feeding fuel into said plurality of air tubes, each of said splashplates having a peripheral edge that is smaller in diameter than the diameter of said air tube, each of said splashplates having a forward facing face defining a particular configuration whereby the fuel discharging from each of said fuel nozzles impinges on each of said splashplates and is broken up into discrete streams of fuel by said particular configuration on the face of each of said splashplates and fed into each of said air tubes to mix with the air therein prior to being admitted into the combustion zone.

6. A plurality of splashplates for the combustor of a microturbine engine as claimed in claim 5 wherein said forward facing face includes a plurality of circumferential segments extending from the center of the splashplate toward the peripheral edge of the splashplate.

7. A plurality of splashplates for the combustor of a microturbine engine as claimed in claim 6 wherein said segments are concave relative to the forward facing face.

8. A plurality of splashplates for the combustor of a microturbine engine as claimed in claim 6 wherein said segments are convex relative to the forward facing face.

9. A plurality of splashplates for the combustor of a microturbine engine as claimed in claim 7 including a recess centered in said forward facing face.

10. A plurality of splashplates for the combustor of a microturbine engine as claimed in claim 8 including a recess centered in said forward facing face.

11. A plurality of splashplates for the combustor of a microturbine engine as claimed in claim 10 including a radial slot formed in each of said segments for flowing fuel through said radial slot into said air tube to mix with the air therein.

12. A plurality of splashplates for the combustor of a microturbine engine as claimed in claim 5 wherein said fuel nozzle consists essentially of a single fuel discharging orifice.

13. A plurality of splashplates for the combustor of a microturbine engine as claimed in claim 5 including spaced tabs mounted on each of said splashplates and attached to each of said complementary air tubes for supporting each of the splashplates in each of said air tubes whereby said splashplates are recessed in said air tubes to prevent the fuel impinging on said splashplates from spilling out of the complementary air tube.

14. A plurality of splashplates for the combustor of a microturbine engine as claimed in claim 5 including a bracket interconnecting each of said splashplates with each of said fuel nozzles for supporting the complementary splashplate in said complementary air tube and each splashplate being recessed from the top of the complementary air tube to prevent the fuel impinging on said splashplates from spilling out of the complementary air tube.

15. In combination, a plurality of fuel nozzles, a complementary number of air tubes in fluid communication therewith and a complementary number of circular shaped splashplates for the combustor of a microturbine engine, each of said plurality of fuel nozzles consisting essentially of a single fuel discharging orifice, each of said air tubes circumferentially mounted about the combustor for feeding air into the combustion zone of the combustor, each of said splashplates mounted in each of said air tubes, each fuel nozzle of said plurality of fuel nozzles feeding fuel into a complementary air tube, each of said splashplates having a peripheral edge that is smaller in diameter than the diameter of said complementary air tube, each of said splashplates being circular in shape and having a forward facing face defining a particular configuration whereby the fuel discharging from each of said fuel nozzles impinges on each of said splashplates and is broken up into discrete streams of fuel by said particular configuration on the face of each of said splashplates and fed into each of said air tubes to mix with the air therein prior to being admitted into the combustion zone.

16. The combination as claimed in claim 15 wherein said forward facing face includes a plurality of circumferential segments extending from the center of the splashplate toward the peripheral edge of the splashplate.

17. The combination as claimed in claim 16 wherein said segments are concave relative to the forward facing face.

18. The combination as claimed in claim 16 wherein said segments are convex relative to the forward facing face.

19. The combination as claimed in claim 17 including a recess centered in said forward facing face.

20. The combination as claimed in claim 18 including a recess centered in said forward facing face.

21. The combination as claimed in claim 16 including a radial slot formed in each of said segments for flowing fuel through said radial slot into said air tube to mix with the air therein.

22. The combination as claimed in claim 15 including spaced tabs mounted on each of said splashplates and attached to each of said complementary air tubes for supporting each of the splashplates in each of said air tubes whereby said splashplates are recessed in said air tubes to prevent the fuel impinging on said splashplates from spilling out of the complementary air tube.

23. The combination as claimed in claim 15 including a bracket interconnecting each of said splashplates to each of said fuel nozzles for supporting the complementary splashplate in said complementary air tube and each of said splashplate being recessed from the top of the complementary air tube to prevent the fuel impinging on said splashplate from spilling out of the complementary air tube.

24. The combination as claimed in claim 15 including a rearwardly facing face portion on said splashplate, said rearwardly facing face portion being configured to prevent the fuel/air mixture from recirculating adjacent to the splashplate.

25. The combination as claimed in claim 24 wherein said configuration of said rearwardly facing face portion is dome shaped.

26. The combination as claimed in claim 24 wherein the configuration of the rearwardly facing face portion of said splashplate is conically shaped.