Method for calibrating a gas turbine combustor during repair or production using a calibration pin

Abstract

A method for calibrating a gas turbine burner during repair or production; the method comprising the steps of: a) providing a gas turbine burner provided with a plurality of holes configured for injecting fuel gas in a flow of air, each hole comprising an outlet having an initial outlet diameter; b) deforming each hole outlet using a calibration device configured to deform the outlet, reducing the initial outlet diameter to a smaller outlet diameter.

Description

[0001] Cross-references to related applications This patent application claims priority to European patent application No. 21171664.2, filed on April 30, 2021, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] This invention relates to the technical field of gas turbine assemblies for power devices. As is known in such assemblies, an introduced airflow is compressed in a compressor and then mixed with fuel (gaseous fuel and / or oil fuel) in a combustor to generate a hot gas flow to expand in the turbine. The combustor includes multiple burners, each having multiple orifices configured for injecting fuel into the airflow. Rotation of the turbine generates rotational work on a rotor, which is then connected to a generator for power production. Within this technical field, the invention relates in detail to how to improve combustion performance. Background Technology

[0003] As is known, a gas turbine for a power device includes a compressor assembly, a combustor assembly, and a turbine assembly. The compressor assembly is configured to compress incoming air supplied at the compressor inlet. The compressed air exiting the compressor assembly flows into a volume (called a “compression chamber”) and from there into a combustor assembly. The combustor assembly typically includes multiple burners configured to inject fuel (at least one type of fuel) into the compressed air stream. Each burner includes multiple orifices configured to inject gaseous fuel into the air stream. The mixture of fuel and compressed air enters the combustion chamber, where it is ignited. The resulting hot gas stream exits the combustion chamber and performs rotational work on a rotor connected to a generator by traveling through the turbine assembly. As is known, the turbine assembly includes multiple stages or rows of rotating blades intervened by multiple stages or rows of stator blades (called guide vanes). The rotating blades are supported by the rotor, while the stator blades are supported by a concentric housing surrounding the turbine assembly (called a “guide vane carrier”).

[0004] To achieve high efficiency, the hot gas flow must have a very high turbine inlet temperature. However, generally, this high temperature involves undesirable high NOx emission levels. So-called "sequential" gas turbines are particularly suitable for reducing these emissions and increasing operational flexibility without compromising efficiency. Generally, a sequential gas turbine comprises first and second combustion stages, each with multiple burners. Currently, at least two different types of sequential gas turbines are known. According to a first embodiment, the first and second burners are annular in shape and physically separated by a turbine blade stage called a high-pressure turbine. Downstream of the second burner is a second turbine unit (called a low-pressure turbine). This type of gas turbine is manufactured by the applicant and is commercially available as "GT26". According to a second embodiment of a sequential gas turbine, the gas turbine does not have a high-pressure turbine, and the burner assembly is implemented in the form of multiple tubular burners arranged in a ring around the gas turbine axis. Each tubular burner includes a first burner and a second burner, which are arranged directly downstream of each other within a common cylindrical housing. This second type of sequential gas turbine is manufactured by the applicant and is commercially available as "GT36". This invention can be applied in all the gas turbines described above, and generally in all gas turbines equipped with a burner having a gas fuel injection port.

[0005] According to the present invention, each of the aforementioned injection orifices includes an inlet connected to a fuel gas source and an outlet perpendicular to the air flowing through the burner slot. As is known, to achieve optimal burner performance in a gas turbine, it is necessary to reduce the fuel gas scatter, for example, to ±2% for the GT26 manufactured by the applicant. Because access to the inside of the burner slot is restricted, the orifices for injecting fuel gas can only be generated by EDM (Electrical Discharge Machining), an inherently imprecise process. In this case, the individual burner scatter of the total fuel gas scatter is ±10%, which causes flame temperature variations greater than 100°C between individual burners. Furthermore, the fuel gas scatter between individual orifices is ±15%, which causes localized flame temperature variations.

[0006] According to existing technological practices, solutions for limiting the gas dispersion of fuel gas leaving the incinerator injection orifices stipulate that the incinerator should be selectively assembled to reduce the circumferential temperature distribution along the downstream measured hot gas path. Calibration orifices can also be installed in each incinerator to reduce fuel flow dispersion. However, this solution is not used because it would increase the pressure drop across the incinerator, requiring a larger gas compressor. Furthermore, this solution does not improve the distribution of fuel gas along the incinerator air duct.

[0007] Based on the practice of this existing technology, there is now a need for a new and creative solution to limit the fuel gas dispersion of the gas leaving the fuel injection orifice in a gas turbine burner. Summary of the Invention

[0008] Accordingly, the main objective of the present invention is to provide a method for calibrating a gas turbine burner, wherein the method can be readily performed during the reconditioning or production of gas turbine components.

[0009] As described above, we refer to a component as a gas turbine assembly, which includes: - Compressor; - At least one burner; - At least one turbine.

[0010] Even if not listed, other smaller components of these components are well known to those skilled in the art. As is known, each burner includes multiple incinerators, i.e., devices configured to inject fuel (in this case, gaseous fuel) into an air stream from a compressor. From this point, according to the main definition of the invention, the method comprises the following steps: a) Provide a gas turbine burner (typically a gas turbine includes multiple burners), the gas turbine burner including multiple orifices configured for injecting gaseous fuel into an airflow (i.e., compressed air leaving the compressor); each gaseous fuel injection orifice includes an outlet having an initial or first outlet diameter, preferably generated as by EDM (the orifice outlet is perpendicular to the airflow). b) By using a tool or device to deform the outlet of the hole, the tool or device being configured such that the outlet of each hole is deformed by changing from the initial EDM outlet diameter to a smaller outlet diameter.

[0011] Controlling the reduction of the outlet diameter using a specific device allows overcoming the aforementioned problems of the prior art, namely, easily ensuring improved airflow distribution and minimal airflow dispersion between individual injection orifices. The resulting orifice diameter is checked using a standard measuring pin to ensure reduced orifice diameter variation, i.e., improved fuel distribution in the incinerator air chamber.

[0012] According to a preferred embodiment of the invention, the reduction of the deformed orifice outlet is performed using a calibration pin device (i.e., preferably comprising a pin having a diameter slightly larger than the initial EDM outlet diameter of each orifice and a device for enlarging the base). In this example, the base is provided with a circular protruding ring around the pin, such that by pressing the pin into each orifice, a circular indentation is obtained at the orifice outlet, thereby uniformly reducing the outlet diameter.

[0013] Preferably, the calibration pin is a hardened pin, that is, a pin made of a material harder than the incinerator.

[0014] The invention also provides a final step to check whether the reduced outlet diameter after deformation is greater than the required minimum diameter. To allow this check, a minimum diameter measuring pin is inserted into each hole.

[0015] Of course, the present invention also relates to any gas turbine incinerator in which the gas injection orifice is calibrated by performing the method according to any one of the preceding claims. Finally, the present invention also relates to any gas turbine assembly comprising at least one incinerator as calibrated as described above.

[0016] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide a further explanation of the invention as claimed. Other advantages and features of the invention will become apparent from the following description, figures, and claims.

[0017] The features of the invention that are considered novel are set forth in particular in the appended claims. Attached Figure Description

[0018] Further benefits and advantages of the invention will become apparent after a careful reading of the detailed description with proper reference to the accompanying drawings.

[0019] However, the invention itself can be better understood by referring to the following detailed description of the invention, together with the appendix. Figure 1 The following describes exemplary embodiments of the present invention, as shown in the accompanying drawings: - Figure 1 and Figure 2 This is a schematic view of two gas turbine components to which the method of the present invention can be applied; - Figure 3 This is a schematic embodiment of a turbine incinerator that can be calibrated according to the present invention; - Figure 4-6 Embodiments of a calibration apparatus suitable for performing the claimed method are disclosed; - Figure 7 and Figure 8 Publicly available for use in separate by Figure 4-6 The device injects fuel gas into the burner orifice in the airflow before and after calibration. Detailed Implementation

[0020] The technical content and detailed description of the present invention are described below with reference to preferred embodiments in conjunction with the accompanying drawings, but are not intended to limit its scope. Any equivalent technical changes and modifications made according to the appended claims are covered by the claims claimed for protection under this invention.

[0021] As mentioned above, the technical field of this application relates to gas turbine assemblies for power devices. Those skilled in the art will know that gas turbine assemblies include a compressor, a burner assembly, and at least one turbine. The compressor and turbine extend along a main axis and are preferably coupled to a common rotor.

[0022] Now refer to Figure 1 , Figure 1 This is a schematic view of a first non-limiting example of a gas turbine assembly for power device 1, in which the method of the invention can be applied. According to Figure 1 In one embodiment, the gas turbine is a so-called "sequential combustion gas turbine," which is equipped with high-pressure and low-pressure turbines. Following the main airflow 2, Figure 1 The gas turbine 1 includes a compressor 3, a first burner 31, a high-pressure turbine 5, a second burner 32, and a low-pressure turbine 7. The compressor 3 and the two turbines 5 and 7 are part of or connected to a common rotor 8, which rotates about an axis 9 and is surrounded by a concentric housing 10. The compressor 3 is supplied with air and includes rotating blades 18 and stator guide vanes 19 configured to compress the air entering the compressor 3. Leaving the compressor, the compressed air flows into a pressure chamber 11 and from there into a plurality of first burners 12 of the first burner 31 arranged in a circular pattern around the axis 9. Each first burner 12 is configured to inject at least one type of fuel (e.g., gaseous fuel connected to at least one first fuel supply section 13) into the compressed air stream. Preferably, the first burner 12 may be defined as a “premixed” burner because it is configured to mix the compressed air and the injected fuel before ignition. The fuel / compressed air mixture flows into an annular first combustion chamber 4, where the mixture is ignited. During startup, the mixture is initially ignited by an igniter (e.g., a spark igniter); once ignited, the ignition is self-sustaining and the igniter is shut off. The resulting hot gas exits the first combustion chamber 4 and partially expands in the high-pressure turbine 5, doing work on the rotor 8. Downstream of the high-pressure turbine 5, the partially expanded hot gas flows into rows of second burners 33, where at least one type of fuel is injected by fuel guns 14 (each burner has one gun). The partially expanded gas, having reached a high temperature and containing sufficient oxygen for further combustion, occurs by auto-ignition in the second combustion chamber 6 (located downstream of the rows of second burners 33). These second burners 33 are also referred to as “reheat” burners. The reheated hot gas exits the second combustion chamber 6 and flows in the low-pressure turbine 7, where it expands and does work on the rotor 8. The low-pressure turbine 7 comprises multiple stages: rows of rotor blades 15 arranged in series in the main flow direction. These rows of blades 15 are intervened by rows of stator guide vanes 16. Rotor blades 15 are connected to rotor 8, while stator guide vanes 16 are connected to guide vane carrier 17, which is a concentric housing surrounding low-pressure turbine 7.

[0023] Now refer to Figure 2 , Figure 2 This is a schematic view of a second non-limiting example of a gas turbine to which the methods of the present invention can be applied. Furthermore, this gas turbine 20 is a "sequential combustion gas turbine." Specifically, Figure 2 A partial view of a gas turbine 20 having a compressor 29, a turbine 21 and a sequential burner 22 is disclosed. Figure 2 The sequential burner 22 has multiple so-called tubular burners, i.e., a number of bolted tubular housings, each of which includes multiple first burners 24, first combustion chambers 25, second burners 26, and second combustion chambers 27. Upstream of the second burners 26, a mixer may be provided for adding air to the hot gas leaving the first combustion chamber 25 and for generating turbulence in the air / hot gas mixture. The sequential burner arrangement is at least partially housed within a housing 28, which supports individual tubular burners 22 arranged in a circular pattern around a turbine axis 23. Furthermore, each of the first burners 24 in this embodiment is a “premixed” burner configured to produce a premixed flame. As the hot gas exits the second combustion chamber 27, it then expands in the turbine 21, doing work on the rotor 30.

[0024] As mentioned earlier, Figure 1 and Figure 2 The example is a non-limiting example of a gas turbine that can be calibrated according to the present invention.

[0025] Figure 3 This is a schematic embodiment of a turbine incinerator that can be calibrated according to the present invention. The incinerator 12 can be used in... Figure 1 and Figure 2 The incinerator is assembled in a gas turbine. In this example, the upstream end 32 is connected to a gaseous fuel source 13, and the downstream end 33 is tapered and has multiple injection holes 31 configured to inject gaseous fuel from source 13 into the airflow. As described earlier, these holes must be calibrated to improve incinerator performance. In practice, the fuel gas holes in this incinerator are generated by EDM, and therefore these holes are not accurately calibrated.

[0026] Figure 4-6 Embodiments of a calibration apparatus suitable for performing the claimed method (i.e., suitable for calibrating the orifices 31 of the incinerator 12) are disclosed. Using the term "calibration," we mean the step of deforming the orifice outlet by using a device configured such that the outlet of each orifice is deformed from its original outlet diameter (generated via EDM technology) to a reduced outlet diameter. Specifically, Figure 4-6A calibration pin 34 device is disclosed, comprising a pin 35 (cylindrical body) having a diameter slightly larger than the initial EDM outlet diameter of each hole 31. Note that these holes 31 are not cylindrical before calibration; they have a slight taper, allowing the pin 35 to enter the holes 31 until the enlarged base 36 of the device presses into contact with the outer surface of the incinerator surrounding the holes 31. The face of the base 36 configured to contact the incinerator surface surrounding the holes 31 is provided with a circular protruding ring 37 arranged around the pin 37. In this example, the circular protruding ring 37 exposes a sharp edge in a circular V-shape that presses against the surface of the incinerator surrounding the holes 31 during use. In this example, the pin diameter is 2.2 mm (marked D), while the V-shaped edge has a diameter equal to 2.5 mm (marked D'). As disclosed in the following figures, the height of the protrusion 37 is configured to deform the edge of the EDM hole 31 outlet.

[0027] Figure 7 and Figure 8 Publicly available for use in separate by Figure 4-6 The device injects fuel gas into the burner orifice in the airflow before and after calibration. Reference numeral 38 refers to the burner surface surrounding orifice 31, i.e., the burner surface in contact with pin base 36. Reference numeral 39 refers to the orifice outlet before calibration, and reference numeral 40 refers to the orifice outlet before calibration. Reference numeral 39 refers to the gaseous fuel flow. As disclosed, after calibration, due to deformation of the outlet itself, the outlet end 40 reveals a smaller diameter than the original outlet diameter. In fact, by pressing pin 35 into orifice 31, base 36 contacts surface 38, and by pressing again (as indicated by F'), a protruding V-shaped ring creates a circular indentation 41 around the outlet. Due to this indentation, the edge of the orifice outlet deforms to reduce the outlet diameter with respect to the airflow. Figure 8 The markings d and d' in the figure refer to the outlet diameter before and after calibration, respectively.

[0028] While the invention has been explained with reference to its preferred embodiments as mentioned above, it is to be understood that many other possible modifications and variations may be made without departing from the scope of the invention. Therefore, it is contemplated that one or more of the appended claims will cover such modifications and variations that fall within the true scope of the invention.

Claims

1. A method for calibrating a gas turbine burner (12) for power equipment during repair or production; the method comprising the steps of: a) Provide: - A gas turbine burner comprising a plurality of orifices (31) configured for injecting gaseous fuel into an airflow, each orifice (31) comprising an outlet (39) having an initial outlet diameter; - A calibration pin device (34) comprising a pin (35) and an enlarged base (36) having a diameter slightly smaller than the initial outlet diameter of each hole (31); The base (36) is provided with a circularly protruding V-shaped ring (37) surrounding the pin (35); b) By pressing the pin into each hole (31) to deform the hole outlet (39) such that a ring indentation is obtained at the outlet (39) of each hole (31) by the protruding V-shaped ring, and such that the outlet (39) of each hole (31) is deformed from the initial outlet diameter to a smaller outlet diameter.

2. The method according to claim 1, wherein In step a), at least the gas injection orifice is manufactured by an EDM process.

3. The method according to any of the preceding claims, wherein, The method also includes a step of checking whether the reduced outlet diameter after the deformation is greater than the minimum required diameter.

4. The method of claim 3, wherein, The inspection process is performed by inserting a measuring pin into each hole to check for the minimum diameter.

Images