Air directed fuel injection

Abstract

A combustion chamber for a gas turbine is provided. The combustion chamber has a pilot burner device, a fuel injector, an ignitor unit and an air blast injector. The pilot burner device has a pilot body with a pilot surface facing an inner volume of the combustion chamber. The fuel injector has a fuel outlet for injecting a fuel into the inner volume, wherein the fuel outlet is arranged at the pilot surface. The ignitor unit is arranged at the pilot surface such that fuel which passes the ignitor unit is ignitable. The air blast injector is adapted for injecting an air blast into the inner volume, wherein the air blast injector includes an air blast outlet arranged at the pilot surface such that the air blast is injectable in the direction to the fuel outlet and the ignitor unit for directing the fuel to the ignitor unit.

Claims

1. A combustion chamber for a gas turbine, the combustion chamber comprising a pilot burner device comprising a pilot body with a pilot surface which is facing an inner volume of the combustion chamber, wherein the pilot body is mounted to a hole in an end face of the combustion chamber such that the pilot surface is perpendicular to a flow of combustion gases in the inner volume, a fuel injector comprising a fuel outlet for injecting a fuel into the inner volume, wherein the fuel outlet is arranged at the pilot surface, an ignitor unit for igniting the fuel inside the inner volume, wherein the ignitor unit is arranged at the pilot surface such that the fuel which passes the ignitor unit is ignitable, and an air blast injector for injecting an air blast into the inner volume, wherein the air blast injector comprises an air blast outlet, wherein the air blast outlet comprises at least one aperture formed in the pilot surface and wherein the fuel outlet, the at least one aperture and the ignitor unit are spaced from each other in a circumferential direction such that air from the air blast injector is configured to direct the air blast in the circumferential direction toward the fuel outlet and then the ignitor unit, which is effective to direct the fuel to the ignitor unit.

2. The combustion chamber according to claim 1, wherein the fuel injector, the ignitor unit and the air blast injector are arranged along the circumferential direction around a centre axis of the pilot burner device.

3. The combustion chamber according to claim 1, wherein the fuel injector comprises a fuel nozzle at the fuel outlet such that the fuel is injectable in an atomized manner.

4. The combustion chamber according to claim 1, wherein the air blast outlet is formed for injecting the air blast with an air blast spray cone.

5. The combustion chamber according to claim 1, wherein the pilot body comprises a first passage which connects the inner volume with an environment of the pilot burner device, wherein the fuel injector is inserted into the first passage, wherein the pilot body further comprises a second passage which connects the inner volume with the environment of the pilot burner device, and wherein the air blast injector is inserted into the second passage.

6. The combustion chamber according to claim 1, wherein the pilot body comprises a common passage which connects the inner volume with an environment of the pilot burner device, and wherein the fuel injector and the air blast injector are inserted into the common passage.

7. The combustion chamber according to claim 1, further comprising a further air blast injector for injecting a further air blast into the inner volume, wherein the further air blast injector comprises a further air blast outlet which is arranged at the pilot surface such that the further air blast is injectable in a direction to the fuel outlet and the ignitor unit for directing the fuel to the ignitor unit.

8. A method for operating a combustion chamber, the method comprising inecting a fuel into an inner volume of the combustion chamber by a fuel injector, wherein the combustion chamber comprises a pilot burner device comprising a pilot body with a pilot surface which is facing the inner volume of the combustion chamber, wherein the pilot body is mounted to a hole in an end face of the combustion chamber such that the pilot surface is perpendicular to a flow of combustion gases in the inner volume, wherein the fuel injector comprises a fuel outlet which is arranged at the pilot surface, igniting the fuel inside the inner volume by an ignitor unit, wherein the ignitor unit is arranged at the pilot surface such that the fuel which passes the ignitor unit is ignitable, and injecting an air blast into the inner volume by an air blast injector which is arranged at the pilot surface, wherein the air blast injector comprises an air blast outlet, wherein the air blast outlet comprises at least one aperture formed in the pilot surface, and wherein the fuel outlet, the at least one aperture and the ignitor unit are spaced from each other in a circumferential direction such that air from the air blast injector is configured to direct the air blast in the circumferential direction toward the fuel outlet and then the ignitor unit, which is effective to direct the fuel to the ignitor unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The aspects defined above and further aspects of the present invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to the examples of embodiment. The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited.

(2) FIG. 1 shows a top view of a pilot burner device according to an exemplary embodiment of the present invention;

(3) FIG. 2 shows a perspective view of a pilot burner device according to FIG. 1;

(4) FIG. 3 shows a schematical view of a pilot burner device comprising three passages according to an exemplary embodiment of the present invention;

(5) FIG. 4 shows a schematical view of a pilot burner device comprising a common passage according to an exemplary embodiment of the present invention;

(6) FIG. 5 shows a schematical view of a pilot burner device comprising a recess into which a fuel injector is installed according to an exemplary embodiment of the present invention;

(7) FIG. 6 shows a schematical view of a pilot burner device comprising a recess into which a fuel injector and an ignitor unit is installed, according to an exemplary embodiment of the present invention;

(8) FIG. 7 shows a perspective view of a pilot burner device comprising a recess with curved lateral surfaces according to an exemplary embodiment of the present invention;

(9) FIG. 8 shows a perspective view of a pilot burner device comprising a recess with a groove-like shape, according to an exemplary embodiment of the present invention; and

(10) FIG. 9 shows a conventional pilot burner device.

DETAILED DESCRIPTION

(11) The illustrations in the drawings are schematic. It is noted that in different figures similar or identical elements are provided with the same reference signs.

(12) FIG. 1 shows a combustion chamber 120 for a gas turbine. In particular, FIG. 1 shows an end face of the combustion chamber 120. The combustion chamber 120 comprises a pilot burner device, a fuel injector 102, an ignitor unit 103 and an air blast injector 104.

(13) The pilot burner device comprises a pilot body 100 with a pilot surface 101 which is facing an inner volume (burner volume) of the combustion chamber 120. The pilot body 100 may be mounted to an open end (e.g. a hole in the end face) of the combustion chamber 120.

(14) The fuel injector 102 comprises a fuel outlet for injecting a fuel into the inner volume. The fuel outlet is arranged at the pilot surface 101. The ignitor unit 103 is adapted for igniting the fuel inside the inner volume, wherein the ignitor unit 103 is arranged at the pilot surface 101 such that the fuel which passes the ignitor unit 103 is ignitable.

(15) The air blast injector 104 is adapted for injecting an air blast into the inner volume. The air blast injector 104 comprises an air blast outlet which is arranged at the pilot surface 101 such that the air blast is injectable in the direction to the fuel outlet and the ignitor unit 103 for directing the fuel to the ignitor unit 103.

(16) A combustion fluid comprises fuel and air streams inside the inner volume along a circumferential direction around a centre axis 105 of the pilot burner device and hence of the combustion chamber 120, for example. Along the flow direction 106 (i.e. the circumferential direction), the air blast injector 104, the fuel injector 102 and the ignitor unit 103 are arranged one after another at the pilot surface 101.

(17) Hence, the air blast of the air blast injector 104 is directed to the fuel injector 102 and further to the ignitor unit 103. Hence, the air blast guides the injected fuel at the fuel injector outlet to the ignitor unit 103 such that more fuel is guided to the ignitor unit 103.

(18) Specifically, the air blast injector 104 injects an air blast along an air blast injecting direction 107, wherein the air blast injecting direction 107 streams generally along the pilot surface 101. In particular, the air blast injecting direction 107 is directed at least with a (directional) component perpendicular to a normal of the pilot surface 101 and streams at least partially parallel to the pilot surface 101. Furthermore, the air blast injector 104 may inject the air blast in such a way that an air blast spray cone 108 is formed. Hence, the air blast stream comprises a larger width at the region of the fuel injector 102 and the ignitor unit 103, such that more injected fuel may be captured and directed to the ignitor unit 103.

(19) Additionally, as shown in FIG. 1, further air blast injectors 104′ may be arranged to the pilot surface 101 for injecting further air blast streams in the direction to the fuel injector 102 and the ignitor unit 103. The further air blast streams may slightly differ in its direction to the air blast injecting direction 107 so that a large air blast streaming field may be generated.

(20) Furthermore, a recess 501 with similar features as shown in FIG. 5 may be formed into the pilot body 100 shown in FIG. 1, wherein the fuel injector 102 may be installed into the recess 501.

(21) FIG. 2 shows the same features as FIG. 1, wherein in FIG. 2 a perspective view of the pilot burner device as shown in FIG. 1 is shown.

(22) FIG. 3 shows a further exemplary embodiment of a pilot burner device according to the invention, wherein the pilot body 100 comprises a first passage 301 which connects the inner volume with an environment of the pilot burner device, wherein the fuel injector 102 is inserted into the first passage 301. The fuel injector 102 may be for example a fuel lance which is detachably inserted into the first passage 301 such that the fuel outlet is positioned at the pilot surface 101. Spaced apart to the first passage 301, the pilot body 100 further comprises a second passage 302 which connects the inner volume with the environment of the pilot burner device, wherein the air blast injector 104 is inserted (e.g. detachably) into the second passage 302. The injectors 102 and 104 and the ignitor unit 103 may for example be tube-like in shape and extend through the pilot body.

(23) As can be taken from FIG. 3, the fuel injector 102 injects the fuel in an atomized manner, i.e. with a fuel spray 304. The air blast injector 104 injects the air blast in an air blast injecting direction 107. As can be taken from FIG. 3, the air blast injecting direction 107 comprises a component which is almost parallel to the pilot surface 101 and comprises an angle perpendicular to a normal of the pilot surface 101.

(24) The fuel injector 102 and hence the second passage 302 are arranged within the pilot body 100 in such a way that the air blast directs with the air blast injecting direction 107 the fuel spray 304 to the direction to a third passage 303 into which the ignitor unit 103 is arranged close to the pilot surface 101.

(25) Furthermore, the first passage 301, the second passage 302 and the third passage 303 are arranged to the pilot body 100 in such a way, that the flow direction 106 of the combustion fluid supports the air blast injector 104. Specifically, along a flow direction 106 of the fluid inside the inner volume, first, the air blast injector 104 is located, next, the fuel injector 102 is located further downstream and finally further downstream the ignitor unit 103 is located.

(26) FIG. 4 shows an exemplary embodiment of the pilot body 100 into which a common passage 401 is formed which connects the inner volume with an environment of the pilot burner device. The fuel injector 102 and the air blast injector are inserted together into the common passage 401. Hence, as more simple design of the pilot body 100 may be provided because for example only a common passage 401 and a third passage 303 for the ignitor unit 103 is necessary. In a further exemplary embodiment can the air blast injector 104 be arranged around the fuel injector 102 as eccentric tube directing the air blast to a desired sector of the circumference of the fuel injector 102.

(27) FIG. 5 shows a further exemplary embodiment of the pilot burner device of the combustion chamber 120. The pilot burner device comprises a pilot body 100 with a pilot surface 101 which is directed to an inner volume of the combustion chamber 120. Furthermore, a recess 501 is formed into the pilot body 100. The fuel outlet of a fuel injector 102 for injecting a fuel into the inner volume is arranged within the recess 501. The recess 501 is located and formed off-centred from the centre axis 105.

(28) Hence, the “off-centred” location of the recess 501 at the pilot surface 101 defines a location of the recess 501 which is spaced apart from the centre axis 105 of the pilot burner device. In particular, the centre axis 105 of the pilot body does not run through the “off-centred” recess 501.

(29) For example, the fuel may be injected by the fuel injector 102 almost parallel to a normal of a section of the pilot surface 101 surrounding the recess 501 and/or parallel to a center axis 105 of the pilot burner device. In the recess 501, the injected fuel is not directly blown away from the recess 501 by a combustion fluid inside the inner volume which streams generally along a flow direction 106. In the recess 501, the fuel has time to spread and diffuse before the combustion fluid in the inner volume streaming along the flow direction 106 takes the injected fuel away to the ignitor unit 103. If the diffused and atomized fuel passes the ignitor unit 103, ignition occurs. In particular, the ignitor unit 103 is located at the pilot surface 101 further downstream with respect to the flow direction 106 in comparison to the further upstream located recess 501 and hence the fuel injector 102.

(30) Further upstream with respect to the flow direction 106, an air blast injector 104 for injecting an air blast into the inner volume is for example arranged to the pilot body 100. The air blast injector 104 comprises an air blast outlet which is arranged upstream with respect to the flow direction 106 in comparison to the fuel injector 102 and the ignitor unit 103. The air blast is injectable in the direction to the fuel outlet and the ignitor unit 103 for directing the fuel to the ignitor unit 103. The air blast injector 104 may be arranged at a surface section of the pilot surface 101 surrounding the recess 501 (see FIG. 6) or, as can be taken from FIG. 5, arranged within the recess 501.

(31) Specifically, the recess 501 may comprise a base area 502 which is spaced from the section of the pilot surface 101 surrounding the recess 501. Furthermore, the recess 501 comprises a lateral surface 503, wherein the lateral surface 503 connects the section of the pilot surface 101 surrounding the recess 501 and the base area 502.

(32) As can be taken in the exemplary embodiment of FIG. 5, the air blast injector 104 may be installed at the lateral surface 503.

(33) The pilot body 100 may comprise a first passage 301 into which the fuel injector 102, such as a fuel lance, is detachably insertable. Furthermore, in particular further upstream of the first passage 301 with respect to the flow direction 106, a second passage 302 may be formed into the pilot body 100, wherein to the second passage 302 the air blast injector 104 is detachably insertable.

(34) FIG. 6 shows a further exemplary embodiment of the present invention, wherein the recess 501 in the pilot body 100 comprises the base area 502 and the lateral surface 503.

(35) The fuel injector 102 is arranged at the lateral surface 503. Furthermore, further downstream of the fuel injector 102 with respect to the flow direction 106, the ignitor unit 103 is arranged to the base area 502 or, as shown in FIG. 6, to the lateral surface 503. The fuel injector 102 injects the fuel into the recess 501 in an atomized manner, wherein the fuel injector 102 directs the fuel directly to the ignitor unit 103 which is located inside the recess 501. Hence, the atomized fuel is ignited when passing the ignitor unit 103. Next, the fluid in the inner volume flowing along the flow direction 106 takes the ignited fuel away from the recess 501 and guides the ignited fuel further into the inner volume.

(36) In order to improve the ignition efficiency, the air blast injector 104 is attached to the pilot body 100 further upstream of the fuel injector 102 and the ignitor unit 103. For example, the air blast injector 104 is located upstream of the fuel injector 102 and the ignitor unit 103 at the surface section of the pilot surface 101 surrounding the recess 501. Alternatively, the air blast injector 104 may also be located at the lateral surface 503 at a location which is located further upstream to the fuel injector 102 and the ignitor unit 103 (see e.g. in FIG. 5).

(37) The term “upstream” and “downstream” relates to the flow direction 106 of the fluid inside the inner volume around the centre axis 105.

(38) FIG. 7 shows an exemplary embodiment of the combustion chamber 120 and the pilot burner device as shown in FIG. 5. As can be taken from FIG. 7, the lateral surface 503 may comprise a curved shape, in particular in a convex shape. As can be taken from FIG. 7, the flow direction 106 of the fluid inside the inner volume flows along a circumferential direction around the centre axis 105. At the base area 502, the fuel injector 102 is installed. The air blast injector 104 is installed at the lateral face 503 such that an air blast is injected along the circumferential direction (flow direction 106) to the fuel injector 102 and further to the ignitor unit 103. The ignitor unit 103 is located onto the pilot surface 101 of the combustion chamber 120.

(39) As can be taken from FIG. 7, the base area 502 may be a hole through which the fuel injector 102 is attachable, such that the fuel outlet is arranged within the base area 502. Furthermore, a further recess 501′ into which a further fuel injector may be installed may be formed into the pilot body 101. In particular, along the circumferential direction around the centre axis 105, a plurality of recesses 501, 501′ may be formed into the pilot body 101.

(40) FIG. 8 shows a pilot burner body 100 with the same features as shown in FIG. 7, whereas the recess 501 is formed with a groove-like profile which has an open area in the side surface of the pilot burner body 100. The groove shaped recess 501 as shown in FIG. 8 may be easier to manufacture with respect to the tubular and donut-like shaped recess 501 as shown in FIG. 7.

(41) It should be noted that the term “comprising” does not exclude other elements or steps and “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.