A BURNER FOR AN EXPANDER, A COMBUSTOR AND EXPANDER COMPRISING THE SAME

Description

DESCRIPTION TECHNICAL FIELD

[0001] This description relates to combustors for turbomachinery and parts thereof. The embodiments described herein refer in particular to combustors suitable for for use in oxy-fuel expanders, such as carbon dioxide expanders su- 10 percritical (sCO expanders).

[0002] In the sense herein intended, an sCO2 expander is an expander in which the carbon dioxide supercritical state is present in at least a portion of the pathway process gas flow inside the expander. EARLY ART 15

[0003] Fossil fuels are a major source of chemical energy used for the generation of mechanical power. Fossil fuels are mixed with air and burned to generate a high-pressure, high-temperature flue gas, which is expanded in an expander. The expander converts the enthalpy of the flue gas in mechanical power available on the expander output shaft and used 20 to drive a load, such as a compressor or compressor unit, or to rotate an electric generator and convert mechanical power into electrical power.

[0004] One of the main concerns regarding the combustion of combustibles fossil fuels concerns the production of carbon dioxide, a greenhouse gas that is considered one of the major contributors to global warming and climate change. 25 tico.

[0005] To reduce the environmental impact of power generation through the combustion of fossil fuels, the possibility of creating a cata- post-combustion ture of carbon dioxide. Systems have been developed to capture -1- rare carbon dioxide, to treat the flue gas released from gas turbines and remove carbon dioxide from it, before discharging the flue gas in the environment. The costs of a plant to capture carbon dioxide are high, both in terms of CAPEX, both in terms of energy required to run the plant, and 5 reduces the overall thermodynamic efficiency of the system. The percentage of carbon dioxide carbon dioxide in the flue gas is low. This requires that large volumes be treated of flue gas through the carbon dioxide capture plant and makes the pro- particularly inefficient capture process.

[0006] In recent years, oxy-fuel cycles, also known as 10 as oxy-fuel cycles or oxy-fuel combustion cycles, where the fuel, such as natural gas or another fossil fuel, is mixed in a oxidizing mixture consisting mainly of oxygen (O) and carbon dioxide (CO ) at high pressure. The mixture of fuel, oxidizer, and carbon dioxide burns in a combustor of an expander, thus producing a pressurized flue gas 15 composed exclusively or almost exclusively of carbon dioxide and ac- here.

[0007] The burnt gas expands in the expander to generate mechanical power. The released flue gas, discharged on the exhaust side of the expander, is cooled fed into a regenerative heat exchanger and further refrigerated to make 20 condense the water, which can then be removed from the refrigerated flue gas. The low temperature flue gas, consisting mainly or exclusively of carbon dioxide, is pressurized and recycled through the heat exchanger re- generative towards the expander combustor.

[0008] The oxygen fed to the expander combustor can be obtained me- 25 diante separation from the ambient air, removing nitrogen from it, so that the working fluid fed to the combustor consists mainly of oxygen and carbon dioxide and does not contain nitrogen. The resulting combustion gas consists of mainly from water and carbon dioxide. Water is removed from the combustion gas I am by condensation and the part of the flue gas without water, which is not 30 recycled to the combustor, can be effectively treated in a capture unit of carbon dioxide. -2-

[0009] The oxy-fuel cycle summarized above is a semi-closed cycle, as only a fraction of the flue gas exits the cycle after the water has been removed from it.

[0010] Oxy-combustion cycles, such as those described above, are particularly 5 interesting in terms of efficiency, reduction of harmful emissions and ease of collection CO turbulence. However, they operate under supercritical CO conditions in corre- 2 2 expander inlet slope and are characterized by high pressure and high temperature values ​​inside the expander and in particular inside the combus- store. These operating conditions place difficult constraints on the design of the 10 crate.

[0011] It is highly desirable to improve the design of combustors suitable for supercritical carbon dioxide expanders or other expanders that operate in con- similar expressions.

[0012] This description concerns improvements to combustor burners, 15 which are in particular aimed at improving the operating conditions of the burner in a supercritical carbon dioxide expander or in turbomachinery where con- equally difficult expressions. SUMMARY

[0013] In one aspect, a burner for a turbomachine is described herein. 20 power generator, which is especially useful in an expander that works in supercritical carbon dioxide conditions, or in other turbomachinery where they are present similar thermodynamic conditions. The burner comprises a central body with an oxidizer duct extending along the axis of the burner and having at least an oxidizer outlet port. The burner also comprises an annular wall in- 25 termedia, which extends coaxially around the central body. Between the central body and the intermediate annular wall is formed a first annular flow path of oxy- dante. At least one fuel passage extends through the annular wall intermediate and has at least one fuel port. An outer annular wall surrounds the intermediate annular wall and a second annular flow path of oxidant is 30 formed between the intermediate annular wall and the external annular wall. -3-

[0014] The burner, as outlined above, promotes mixing between the reagents and optimizes the flame in the combustor, and is particularly suitable to meet the requirements sites of an Allam cycle.

[0015] In particularly advantageous embodiments, the burner com- 5 also takes a first vortex flow generator positioned in the first path of annular flow of oxidant and / or a second vortex flow generator positioned born in the second annular flow path of oxidant. Preferably, both the first that the second vortex flow generator are provided in combination. This improves burner efficiency. 10

[0016] A combustor for a turbogenerator is also described here. of power, comprising a burner as outlined above, as well as a turbomachine power generating unit, or expander, comprising one or more burners.

[0017] Further features and embodiments of the burner and the tur- machine including said burner(s) are described and set out below 15 in the attached claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Reference is now made briefly to the attached drawings, in which: Fig. 1 illustrates a schematic of one embodiment of a system of expander according to this description; 20 Fig. 2 is a sectional view of an expander in a simple representation. multiplied; Fig. 3 is an enlarged and more detailed sectional view of the combustor of the expander in Fig. 2; Fig. 4 is a front view of the burner in one embodiment; 25 Fig. 4A is an enlargement of a central area of ​​Fig. 4; Fig. 5 is a cross-sectional view along line VV of Fig. 4; Fig. 5 is a sectional view of the burner of Fig. 4; Fig. 6 is a side view of the liner in one embodiment; Fig. 7 is a sectional view of the liner of Fig. 6 along a contem- 30 its longitudinal axis; -4- Fig. 7A is an enlargement of Fig. 7; Fig. 8 is an axonometric view of the transition piece in a form of realization; Fig. 9 is a sectional view of the transition piece of Fig. 8; 5 Fig. 10 is an axonometric sectional view of a first component of the transition piece in another embodiment; Fig. 11 is an axonometric view of the first component of Fig. 10; Fig. 12 is an axonometric section view of a second component of the transition piece of Fig. 10; 10 Fig. 13 is an axonometric view of the second component of Fig. 12; and Figs. 14, 15 and 16 are diagrams of different chamber configurations combustion. DETAILED DESCRIPTION

[0019] The diagram in Fig. 1 illustrates a simplified power supply system that 15 includes an oxy-combustion cycle that runs on super carbon dioxide. critical at the expander inlet (short sCO cycle), for example perhaps an Allam cycle or a NET Power oxy-combustion cycle.

[0020] The power generating system 1 shown in Fig. 1 comprises a tur- bina or expander 3 which comprises an expansion section 5 and a combustor 7. The 20 combustor 7 can be, for example, an annular combustor, a tubular combustor- re, a tubular-annular combustor (also known as a tubular-annular combustor) or similar. In the embodiments described herein, the combustor is a tu- The combustor comprises a plurality of combustor chambers arranged in- I return to the axis of rotation of expander 3, as shown in more detail in the 25 figures below and described in more detail below. The combustion chambers are housed in an external case of the expander, as will be described in more detail. detail below.

[0021] Reference number 7.1 in Fig. 2 designates a combustion chamber of a tubular or tubular-annular combustor. In some embodiments, each 30 combustion chamber 7.1 is housed in a respective seat formed in a case, as will be described in more detail below with reference to Fig. 3. The -5- combustion chambers 7.1 are arranged circumferentially around an axis of AA rotation of the expander 3.

[0022] The combustor 7 is fed with a flow of oxidizer delivered from a source of oxidant. The oxidant may be oxygen (O2). In some embodiments, 5 The oxidant is a mixture of oxygen and carbon dioxide (CO2). The oxidant flow te, or the oxygen that is part of the oxidant mixture, can be produced by an air separation unit 9 (Fig. 1) which represents a source of oxidant. The air separation unit 9 can remove nitrogen or nitrogen and carbon dioxide from the ambient air to produce the required oxidant flow, which is supplied at- 10 through an oxidizer supply line 11 to the combustor 7 of the expander 3.

[0023] Reference number 13 indicates a fuel supply line. for example, suitable for supplying natural gas, such as methane, to combustor 7, in particular to each combustion chamber 7.1. The oxidizer and fuel are fed on a front side of the expander 3 to the high pressure combustor 7, to 15 example at 50 barA or more, preferably at a pressure equal to or greater than 100 barA, more preferably equal to or greater than 150 barA, even more preferably equal to or greater than 200 barA. In some embodiments, the pressure exceeding king of the cycle performed in the thermodynamic system depicted in Fig. 1 can be equal to or greater than 250 barA, or greater, or equal to or less than 1000 barA, 20 or equal to or less than 800 barA, or equal to or less than 600 barA. The mi- choice of oxidizer-fuel is burned in combustor 7. The flue gas hot and pressurized gas resulting from combustion expands in the cross-section of expansion 5 of expander 3.

[0024] In some embodiments, the temperature at 25 of the entrance of the gas expansion flow path, i.e. at expander rotor inlet temperature, may be equal to or greater than 800 °C, and preferably equal to or lower than 1500 °C.

[0025] After expansion, the released combustion gas is discharged onto a la- exhaust of the expander 3 into an exhaust line 15. The combustion gas in the 30 exhaust line 15 can be at about 600 °C, for example, and at a pressure between between 10 barA and 100 barA, for example between 20 barA and 60 barA. -6-

[0026] The power of expander 3 can be higher than 50 MW, for example equal to or greater than 100 MW, e.g. 150 MW or greater, e.g. 200 MW or more. In embodiments, the rated power is equal to or greater than 300 MW. In some embodiments, the nominal power is equal to or less than 5 to 2000 MW, for example equal to or less than 1500 MW, or equal to or less than 1000 MW. For example, the nominal power can be between 200 MW and 650 MW.

[0027] The intermediate values ​​between the upper limit are also expressly disclosed here. upper and lower of each interval mentioned above. 10

[0028] The power supply system of Fig. 1 also includes an exchanger regenerative heat 17, in which the hot exhaust flue gas, which flows through- through a hot side 17.1 of the regenerative heat exchanger 17, it is cooled given by heat exchange with a flow of refrigerated exhaust flue gas flowing through a cold side 17.2 of the regenerative heat exchanger- 15 vo 17. The flue gas discharged from the hot side 17.1 of the heat exchanger regenerative 17 is further cooled in a refri- generation 19 at a temperature that causes water vapor to condense contained in the exhaust flue gas. Condensed water is removed from the gas of exhausted combustion in a water / gas separator 21. 20

[0029] The exhausted, dehydrated and refrigerated flue gas, consisting mainly of (e.g. up to 90% by weight) or exclusively from carbon dioxide, via compressed in a combustion gas compressor 23 at the pressure of the side expander inlet 3. While in the diagram of Fig. 1 the gas compressor is combustion 23 is represented graphically as a single compressor, in some 25 In some embodiments, it is possible to use a multiple compressor. For example, pio, the flue gas compressor 23 can be a multistage compressor or a compressor train, and may include one or more intercoolers.

[0030] The compressed combustion gas, consisting mainly of carbon dioxide bonica and delivered by the combustion gas compressor 23, is partially 30 removed from the cycle through a discharge line 24. Most of the com- compressed combustion gas is divided into a first part of recycled combustion gas -7- to and a second part of recycled flue gas. The first part of recycled flue gas recycled combustion gas is delivered through the cold side 17.2 of the heat exchanger. regenerative flow 17 and is heated by heat exchange with the combustion gas hot combustion flowing through the hot side 17.1 of the heat exchanger re- 5 generative 17, and recycled into the expander 3 through a recycling line 25. The gas of Recycled combustion through recycle line 25 is fed to the combustor 7 and mixed with the combustion gas generated inside it, as will be described in more detail below.

[0031] A lateral flow of cooled and dehydrated flue gas, consisting of 10 from the second part of recycled flue gas, is delivered through a line of cooling 27, which bypasses the regenerative heat exchanger 17, towards expander 3 components requiring cooling. An additional lateral flow A volume of refrigerated and dehydrated flue gas can be delivered through a line 28 to air separator 9 and / or to oxidizer supply line 11 for ag- 15 carbon dioxide to oxygen from the air separation unit 9. The gas of combustion coming from line 28 and the oxygen coming from the separation unit air ration are mixed to form the oxidant stream that is delivered fed to combustor 7. The oxidizer flow delivered to combustor 7 may contain, for example, approximately 20% by volume oxygen and 80% by volume 20 carbon dioxide. Adding carbon dioxide to the oxidizer stream prevents corrosive damage to piping and expander components, which can be caused by the use of pure oxygen as an oxidant. In addition, carbon dioxide misce- with oxygen in the oxidizer stream mitigates safety concerns related to to the supply of pure oxygen to the combustor and helps regulate the reactivity 25 of the mixture inside the combustor. The percentages indicated above are purely are for illustrative purposes only and should not be construed as limiting the scope of the pre- hear description.

[0032] To recover additional heat from the regenerative heat exchanger 17, the oxidizer supply line 11 may include a heating section 30 ment 11.1 which extends through the regenerative heat exchanger 17, in mo- such that the oxidant is heated by heat exchange with the gas hot combustion flowing into the hot side 17.1 of the regenerative heat exchanger -8- rative 17 before being fed to combustor 7.

[0033] The expander 3 may include an output shaft end 31 which may be be integral with the central portion of the rotor or can be assembled with the central portion of the rotor by bolting, welding, Hirth connections or 5 grooved profile, or similar, or a combination thereof. The mechanical power generated from the expansion of the combustion gas in the expansion section 5 of the expander 3 is available on the output shaft end 31 for mechanical traction or for gene- power ration. In the exemplary embodiment of Fig. 1, the end of the output shaft 31 is mechanically coupled to a generator 10 electric 33, directly or through a gear box, a coupling or their com- binations. The electric generator 33 is in turn electrically coupled to a network of electrical power distribution 35. In Figs. 1 and 2, the end of the shaft of outlet 31 is shown on the rear side of the expander 3. In other embodiments ne, not shown, the end of the output shaft 31 may be arranged on the front side 15 rear of the expander. In other embodiments, not shown, it is possible to provide two output shaft ends, one on the front side and one on the rear side of the expander.

[0034] Continuing to refer to Fig. 1, Fig. 2 illustrates a se- simplified representation of the expander 3 in one embodiment. The expander 3 can 20 comprise an outer casing 41 which houses the combustor 7. In embodiments tion, the outer case 41 comprises a high pressure case 41.1 and a pressure case low pressure exhaust 41.2. The high pressure case 41.1 can take the form of a cylinder comprising a monolithic body, for example manufactured by forging, casting, or a combination thereof. That is, the outer case may be 25 a vertically divided case. The monolithic body extends around the longitudinal axis tudinal of the expander, i.e. around the axis of rotation.

[0035] The low pressure exhaust box 41.2 can be positioned on the side of exhaust, i.e. on the rear side, of the expander 3, i.e. on the side opposite to the combustor 7. 30

[0036] In some embodiments, the low pressure exhaust box 41.2 forms an exhaust plenum 41.3, through which the exhausted combustion gas -9- is downloaded from expander 3.

[0037] Reference numbers 45, 47 indicate bearing arrangements, which sup- rotate a rotor 43 of the expander 3. For example, the arrangement of cu- bearing 45 on the side opposite the combustor 7, may include an axial bearing 5 or thrust bearing in combination with a radial bearing, or a bearing having capa- axial-radial bearing arrangement. The bearing arrangement 47 on the combustion side store may include a radial bearing. An in-arrangement is also possible. inverted, with a bearing having axial load capacity arranged on the side of the com- bustor. 10

[0038] The end of the output shaft 31 of the rotor 43 can be mechanically te coupled to the driven machine (electric generator 33) through flanges 49. Bearing arrangements 45, 47 may be arranged in bearing housings scinetto, not shown in detail.

[0039] The rotor 43 is surrounded by an inner casing 51, which may be formed from 15 a plurality of sections arranged in sequence in an anterior to posterior direction. In Fig. 2 the inner case 1 comprises two case sections arranged in sequence in direction from front to back, that is, parallel to the axis of rotation. The case internal 51 can be divided horizontally, that is, it can comprise two por- coupled to each other along a plane containing the axis of rotation of the rotor- 20 re 43. If the inner box comprises two sections arranged in sequence in the direction axial, each section can in turn be divided into two portions along a plane containing the axis of rotation of the rotor 43.

[0040] The inner case 51 is completely or partially housed in the case high pressure 41.1. In some embodiments, as shown in Fig. 2, 25 the inner casing 51 protrudes into the low pressure discharge casing 41.2.

[0041] One or more annular fluid chambers 42 are formed between the inner casing 51 and the outer case 41. In particular, in the exemplary embodiment mo- As shown in Fig. 2, the annular chamber 42 comprises two annular fluid chambers 42.1 and 42.2 arranged in sequence and separated by a septum 44. The fluid pressure 30 inside the two annular fluid chambers 42.1 and 42.2 may be different. Ad -10- for example, the annular fluid chamber 42.1 may be at a higher pressure greater than the rear annular fluid chamber 42.2. In use, under conditions of steady state, to the rear fluid chamber 42.2 and to the front fluid chamber 42.1 can be supplied with refrigerant or cooling fluid, for example 5 with refrigerated and dehydrated flue gas from cooling line 27.

[0042] In some embodiments, the inner casing 51 is provided with conduits cooling, one of which is shown schematically in 51.1 in Fig. 2. I cooling ducts provide fluid coupling between one or each of several annular fluid chambers 42.1, 42.2 and the inside of the inner case 51. The 10 compressed recycled flue gas, consisting mainly of carbon dioxide nica, can flow from the annular fluid chambers inside the inner case 51 for cool or purge the annular cavities inside the inner casing 51. Ducts external cooling can be supplied in combination or as an alternative to the cooling ducts that extend through the inner casing. 15

[0043] The expander may be arranged to expand the combustion gas through the gas expansion flow path with a pressure drop of at least 150 bar, preferably at least 250 bar, more preferably between 250 and 400 bar. To expand to derate the combustion gas generated in the combustor 7 a high number is preferred of expansion stages. In the exemplary embodiment of Fig. 2, 20 The expander 3 comprises eight stages, each configured as an expansion stage axial. In other embodiments a different number of stages can be envisaged expansion, preferably equal to or greater than four, more preferably equal to or su- greater than five. In some embodiments, the number of expansion stages It can be more than eight, such as nine, ten, eleven or more. 25

[0044] Each expansion stage comprises an annular row of stationary blades ries 53, also called vanes 53, arranged in a stationary manner in the inner case 51 and forming nozzles at the entrance of the flow path of expansion.

[0045] Each expansion stage also comprises a respective annular row 30 of rotor blades 55, arranged downstream of the respective annular row of stationary blades 53 along an expansion flow path extending from combustor 7 through -11- the expansion section 5 to the exhaust plenum 41.3 in a direction from front to rear.

[0046] The rotor blades 55 are part of the rotor 43, i.e. they are connected to it to rotate with the rotor shaft. In some embodiments, each fi- 5 the rotor blade ring 55 is connected to a respective rotor disk, not shown in detail. The structure of the rotor and rotor discs is not relevant and is not shown in detail.

[0047] In embodiments, the rotor 43 further comprises a portion of al- front shaft 65 and a rear shaft portion 67. In embodiments, the 10 combustor 7 extends around the front shaft portion 65. In some forms of construction, the exhaust plenum 41.3 extends around the shaft portion rear 67.

[0048] A balance drum 69 may be attached to the rotor 43 for rotation- king with it. In the embodiment of Fig. 2, the balance drum 69 15 comprises a first portion of balancing drum 69A and a second portion balancing drum 69B connected to each other by tie rods 70.

[0049] Still referring to Figs. 1 and 2, a general configuration of the combustor 7 in one embodiment is shown in Fig. 3. The embodiment The design of Fig. 3 is based on a tubular combustor architecture, where 20 the expander comprises a plurality of tubular liners, wherein each liner contains one or more burners, and in which each liner is surrounded by its own tubular casing. In other embodiments, as mentioned above, the combustor may be a tubular-annular combustor (also known as tubular-annular), or otherwise a combus- ring store. 25

[0050] Turning now to Fig. 3, in the embodiment illustrated the expander comprises a tubular combustor, which comprises a plurality of combustor units store. The units are arranged around the expander's rotation axis AA. A combustor unit is shown in a longitudinal sectional view in Fig. 3. The combustor unit will be referred to here simply as “combustor” and com- 30 takes a combustor case 101 which houses a liner 103. Each liner 103 has -12- a longitudinal axis BB. Since the combustor units are part of a combus- tubular store, the 103 liners are positioned with their longitudinal axes BB on a conical surface, whose axis coincides with the axis of rotation AA of the expander. In some embodiments, the angle between the axes AA and BB may be between 0° and 5 80°, or between 0° and 60°, in some embodiments between 15° and 40°. The angle between the axes yes AA and BB is chosen as a compromise between the need to reduce the dimensions ra- expander dials and improve the combustor design (which improves utilization (using smaller angles), and the overall design constraints of the expander, such as the size and position of the rotor shaft and bearings (which require 10 larger angles).

[0051] In some embodiments, the combustor units may be al- lodged in a combustor box, which can be manufactured separately from the Main outer case of the expander. The two cases can be connected to each other. to the other by means of a flanged coupling. In this way it is possible to improve 15 the manufacturability of the case. In the attached drawings a single case is shown for mo- of simplicity.

[0052] In other embodiments, the combustor may be an anu- tubular or annular combustor. The general configurations of tubular combustors ri, tubo-annular combustors and annular combustors are known in themselves and are 20 summarized in the diagrams of Figs. 14, 15 and 16, respectively. As shown in the Fig. 14, the tubular combustor comprises individual liners 103, arranged around the axis AA of the turbomachinery and coupled to each other by crossfire tubes 104. A tubular-annular combustor, as shown schematically in Fig. 15, com- takes an annular pressure shell 106, which houses the liners 103 and the crossfi- tubes 25 re 104. A schematic representation of an annular combustor is shown in the Fig. 16. In this case, the combustor comprises a single liner 103 which develops symmetrically around the rotation axis AA of the expander and has an inter-liner no, generally conical, and an external liner, generally conical, coaxial between they. The burners are arranged in a ring around the axis of the machine AA and are al- 30 loggias in the liner, as shown schematically in Fig. 16.

[0053] The liner 103 will be described in detail below with reference to the figures. -13- subsequent. As mentioned, liner 103 extends along a longitudinal axis BB and has a front end 103F and a rear end 103A. A side wall 105 generally cylindrical liner 103 extends between the front end 103F and the rear end 103A. The sidewall 105 has an outer surface 105A and 5 an internal surface 105B and surrounds the combustion chamber 7.1 of the combustor or combustor unit 7.

[0054] The combustor 7 comprises at least one burner 107 at of the front end 103F of the liner 103. In some embodiments, the bru- ciator 107 is coupled to a front end closure or cover 106 of the li- 10 ner 103. In some embodiments, the front end closure 105 of the liner 103 comprises a plurality of openings through which the combustion gas recycled gas, consisting mainly of carbon dioxide, can enter the chamber of combustion 7.1.

[0055] As detailed below, burner 107 is coupled 15 of fluid with a fuel inlet 109 and an oxidizer inlet 111. The fuel inlet 109 is in turn in fluid coupling with the line of fuel supply 13 (Fig. 1) and receives the fuel from it, example gaseous fuel, such as natural gas. The oxidizer inlet 111 is in fluid coupling with the oxidizer supply line 11 and receives 20 the oxidant from it, the oxidant being mainly composed of oxygen and an- carbon dioxide, as mentioned above.

[0056] The combustor 7 further comprises a transition piece 113 positioned at the rear end 103A of the liner 103. The transition piece ne 113 forms an extension of the duct formed by the liner 103 towards the array of 25 stationary nozzles 53 and guides the generated combustion gas into the combustion chamber 7.1 towards the expansion flow path formed by the stationary blades and expander rotary.

[0057] In the embodiment of Fig. 3, since the combustor is a combus- tubular store, each combustion chamber 7.1 extending along the longitudinal axis 30 tudinal BB of the respective liner 103 joins in a respective transition piece of the plurality of transition pieces 113 positioned circumferentially around -14- to the axis of rotation AA. In other embodiments, the combustor may be a annular combustor that includes a conical-shaped liner. In this embodiment tion, not shown, the tapered liner joins with a single transition piece ge- blackly conical. In both cases, the transition piece(s) connect 5 fluid flow liner with the row of stationary blades 53 of the first stage of expander expansion, positioned at the entrance of the path of expansion flow.

[0058] The combustor 7 further comprises a sleeve 115, arranged around the li- ner 103 and substantially coaxial with it. In particular, the sleeve 115 is posi- 10 connected between the liner 103, i.e. between its side wall 105, and the combustion box store 101. The sleeve 115 includes a front end 115F and a rear end rear 115A. The front end 115F of the sleeve 115 is coupled to a internal surface of the combustor box 101. The sleeve 115 divides a space between the combustor box 101 and the liner 103 in an internal annular space 117 and one 15 external annular space 119. The external annular space 119 surrounds the annular space internal 117. The internal annular space 117 and the external annular space 119 are so- essentially coaxial.

[0059] Since in the embodiment of Fig. 3, the combustor is a combus- tubular store, each generally cylindrical liner is surrounded by a sleeve 20 115 cylindrical. The inner annular space and the outer annular space that surround it each liner 103 extends coaxially to liner 103, i.e. in the direction of the longitudinal axis BB and have a cylindrical cross-section. In other forms of realization, not shown, where the combustor is an annular combustor, the mani- cooked is generally conical and coaxial to the rotation axis AA of the expander. 25 internal and external annular spaces are conical and coaxial to the axis of rotation AA.

[0060] As described above, the exhausted flue gas is returned towards the combustor 7 of the expander 3. As described in relation to Fig. 1, the gas combustion is added to the oxygen separated from the air by the se- unit air comparison 9. The oxidant is made up of a mixture of oxygen and com- 30 recycled combustion gas is delivered to combustor 7 through the oxidizer inlet 111. -15-

[0061] A further flow of recycled flue gas, from which the con- dense has been removed, it is delivered to the expander through the recycling line 25 and is fed to the combustor 7 through a first process gas inlet 120, which is in fluid coupling with the internal annular space 117 as de- 5 written below. Yet another stream of recycled flue gas is delivered to the expander 3 through the cooling line 27, which is coupled ment with a second process gas inlet 121. The second process gas inlet of process 121 is in fluid coupling with the external annular space 119 in a position downstream of the front end 115F of the sleeve 115, i.e. in 10 a position between the expander expansion flow path and the front end upper 115F of sleeve 115. The first process gas inlet 120 is therefore connected to the combustor 7 in a position upstream of the position of the second in- process gas inlet 121. Between the second process gas inlet 121 and the front end 115F of the sleeve 115 is formed an isolation chamber 15 thermal. The insulation chamber is formed by the external annular space 119, or by a part of the same, which extends around the sleeve 115 and the liner 103. The thermal insulation chamber can be filled with stagnant process gas which It represents an inert, heat-insulating gas, consisting mainly of carbon dioxide. high pressure nica, which represents an efficient insulating material. 20

[0062] In the embodiment of Fig. 3, the front end 115F of the ma- nicotto 115 is positioned in an intermediate position between the front end 103F of the liner 103 and the rear end 103A of the liner, i.e. between the two ends 103F and 103A of liner 103.

[0063] Therefore, the liner 103 protrudes in a forward direction beyond the sleeve 115 25 surrounding the liner 103. In this embodiment, the combustor comprises also a front plenum 127, positioned at the front end rear 103F of liner 103. In particular, in Fig. 3, the front plenum 127 surrounds the front end 103 of the liner 103, which protrudes into the front plenum 127. 30

[0064] In other embodiments, the front end 103F of the liner and the front end 115F of the sleeve 115 can be aligned substantially -16- along the BB axis. Therefore, the sleeve 115 will be flush with the liner 103 in corre- the protrusion of its rear extremities.

[0065] In Fig. 3, the front plenum 127 extends parallel to an axis of the liner 103 from the front end 115F of the sleeve 115 in a forward direction towards 5 a lid or closure 129, which closes the front side of the combustor box 101. The fuel inlet 119 and the oxidizer inlet 111 extend through towards closure 129. Closure 129 closes the front plenum 127 on its side front.

[0066] The front plenum 127 is in fluid coupling with the annular space 10 internal 117. The first process gas inlet 120 is in fluid coupling with the front plenum 127, so that the process gas, i.e. the gas combustion recycled from the exhaust of expander 3 through the recycle line 25 and the first process gas inlet 120, flows through the front plenum 127 and from it into the internal annular space 117 in an anterior to posterior direction. 15 internal annular space 117 and / or the front plenum 127 may be coupled fluid flow to the combustion chamber 7.1 through holes, openings or passages saints, which extend across the sidewall 105 of the liner. A description of the holes, openings or lights extending through the side wall 105 of the liner will be provided later. The lights, holes or openings in the side wall 105 of the 20 liners allow the process gas, consisting mainly of carbon dioxide, flowing through the internal annular space 117, to flow into the combustion chamber 7.1 as a cooling fluid or dilution fluid.

[0067] In some embodiments, the combustor 7 further comprises a ple- rear num 131 positioned at the rear end 103A of the 25 liner 103. For example, the rear plenum 131 may surround the rear end 103A of the liner 103. In some embodiments, the rear plenum 131 circum- also includes the transition piece 113, i.e. the transition piece is at least partially housed in the rear plenum 131.

[0068] In Fig. 3 the rear plenum 131 is in fluid coupling with the 30 outer annular space 119, which surrounds the liner 103 and the sleeve 115. The space outer ring 119 may extend from the rear plenum 131 towards the anterior end. -17- 103F rear of liner 103.

[0069] In the embodiment of Fig. 3, the second pro-gas inlet cess 121 is positioned in correspondence with the rear plenum, that is to say directly mind coupled to it. In other embodiments, not shown, the second 5 process gas inlet 121 can be positioned in an intermediate position along the development of the external annular space 119 between its posterior end and the rear plenum 131.

[0070] The rear plenum 131 may be in fluid coupling through cooling ducts (not shown) with the components facing the 10 expansion flow path, such as stationary blades and / or rotating blades of the rotor- king.

[0071] In the embodiment of Fig. 3, the internal annular space 117 is in coupling of fluid at its rear end with a ring- the cooling 113A of the transition piece 113. As will be explained in 15 more detail below, the cooling ring can be formed between a internal conduit and an external conduit of the transition piece 113, wherein the conduit internally forms a hot gas path capable of placing the ca- in fluid coupling combustion chamber 7.1 with the expansion flow path of an expander 3. The rear plenum 131 extends around the outer duct of the transition piece 20 113.

[0072] The process fluid delivered through the first process gas inlet 120 flows through the internal annular space 117 and partially enters the chamber combustion chamber 7.1 through openings extending through the wall of the liner 103. The remaining process gas flows from the first internal annular space 117 25 in the cooling ring 113A in a flow direction corresponding to the di- flow reaction of the combustion gas generated in the combustion chamber 7.1 and flowing towards the expansion flow path. The process fluid flows from the cooling ring 113A through the cooling openings formed in the transition piece, which will be described in more detail below, and ref- 30 cools the inner surface of the transition piece 113 by effusion or refrigeration film cooling. -18-

[0073] An embodiment of the at least one burner 107 positioned in correspondence of the front end of the combustion chamber 7.1 is illustrated in Figs. 4, 4A and 5.

[0074] The burner 107 comprises a concentric arrangement of ducts, through 5 towards which the oxidant, coming from the oxidant inlet 111, and the fuel the, coming from the fuel inlet 109, are delivered into the combustion chamber combustion 7.1, where they are intimately mixed and burned to generate the flux I know of compressed, hot combustion gas which then expands through the expander expansion flow path. 10

[0075] In the embodiment of Figs. 4, 4A and 5, the burner 107 com- takes a central body 135, which extends in a longitudinal direction parallel to te to the longitudinal axis BB of the liner 103. If a single burner is facing the combustion chamber 7.1, the central body 135, and therefore the burner 107, can be coaxial with the liner 103 and the combustion chamber 7.1, as shown in the 15 Fig. 3.

[0076] The central body 135 is surrounded by an intermediate annular wall 137, which extends coaxially around the central body. The central body 135 and the wall intermediate annular 137 form a first annular flow path of oxidant 139 between them. More specifically, the first annular flow path of oxidant 139 is 20 formed between an external wall of the central body 135 and an internal wall of the wall intermediate annular 137. In some embodiments, the outer surface of the central body 135 and the inner wall of the intermediate annular wall 137 are cylindrical drainage channels, at least in their most downstream portion, so that the first flow path so that the ring of oxidant 139 has a constant circular ring cross-section. 25

[0077] The intermediate annular wall 137 forms a fuel passage 141 to the its interior. The fuel passage 141 is in fluid coupling with at least no fuel light 143. In the embodiment of Figs. 4, 4A and 5, the Fuel passage 141 includes a plurality of fuel ports 143. In some embodiments, the fuel port 143 or the plurality of ports 30 of fuel 143 are positioned on a front surface 137A of the wall intermediate annular 137. The fuel ports 143 are positioned correspondingly -19- at or near the distal end, i.e. the posterior end of the intermediate annular wall 137. In the embodiment of Figs. 4, 4A and 5, the fuel ports 143 are formed in a front end surface of the intermediate annular wall 137. The anterior end surface may be planar- 5 kings.

[0078] If a plurality of fuel ports 143 is provided, they may be arranged with a constant pitch around the burner axis BB, as shown in Fig. 4.

[0079] In the embodiment of Figs. 4, 4A and 5, the burner 107 com- 10 further takes an outer annular wall 145, which surrounds the intermediate annular wall dia 137. The intermediate annular wall 137 and the outer annular wall 145 form a second annular flow path of oxidant 149 between them. In some forms of realization, the cross-sectional area of ​​the first annular flow path of oxidant 139 is less than the cross-sectional area of ​​the second path of 15 annular flow of oxidant 149. For example, the cross-sectional area of ​​the pri- my annular oxidizer flow path 139 can be between 50% and 70%, preferably between 60% and 65% of the cross-sectional area of ​​the se- second oxidant flow path 149.

[0080] More specifically, it is formed between an outer wall of the annular wall in- 20 termedia 137 and an inner wall of the outer annular wall 145. In some forms of realization, the external surface of the intermediate annular wall 137 and the in- the outer annular wall 147 are cylindrical, at least in their portion further downstream, so that the second annular oxidizer flow path 149 has a constant circular ring cross-section. 25

[0081] To impart a tangential or vortical motion to the flowing oxidant in the first annular oxidizer flow path 139, it is possible to place a pri- vortex flow generator 151 in the first annular flow path of oxy- dante 139. This vortex movement is useful to improve mixing, mi- improve combustion efficiency and control the flow path inside the 30 the combustion chamber 7.1. In the embodiment of Figs. 3 and 4, the first vortex flow generator 151 includes a plurality of first inclined blades, -20- which extend between the external surface of the central body 135 and the internal surface of the intermediate annular wall 137, and is configured to impart a motion tangential to an oxidizer flow in the first annular oxidizer flow path.

[0082] In some embodiments, the burner 107 further comprises a se- 5 second vortex flow generator positioned in the second annu- flow path of oxidant. In the embodiment of Figs. 4, 4A and 5, the second gene- vortex flow fan 153 includes a plurality of second inclined blades 153.1, which extend between the outer surface of the intermediate annular wall 137 and the inner surface of the outer annular wall 145, and is configured to impart 10 a tangential movement to an oxidant flow in the second flow path oxidizer ring.

[0083] In other embodiments, not shown, the first flow generator vortex or the second vortex generator, or both between the first vortex generator- thing and the second vortex generator, may include oxygen inlet ports 15 inclined dante, which are configured to feed an oxidizer stream having a tangential velocity component in the respective flow paths of oxidant anu- lare.

[0084] In the embodiment of Figs. 4, 4A and 5, the first generator of vortex flow and the second vortex flow generator are respectively act 20 to induce a tangential movement in the same direction as in the first path of annular oxidizer flow than in the second annular oxidizer flow path.

[0085] In the embodiment of Figs. 4, 4A and 5, at least one conduit fuel supply 155 extends through at least one of the second pa- the inclined 153.1 from the outer annular wall 145 to the intermediate annular wall 137. 25 Each fuel supply conduit 155 includes a inlet 155.1, which is in flow coupling with a com- inlet plenum fuel 157, and an outlet end 155.2 in flow coupling with the pass- fuel sample 141 extending along the intermediate annular wall 137.

[0086] In some embodiments, in addition to the first annular flow path of 30 oxidizer 139 and the second annular flow path of oxidizer 149, the burner -21- 107 may have a third oxidizer flow path inside the central body 135. The third oxidizer flow path may include a flow conduit of oxidizer 159 in the central body 135, which is in fluid coupling with one or more 161 oxidizer outlet ports, positioned at or adjacent to 5 at the front distal end of the central body 135. In Figs. 4 and 5 the exit lights 161 oxidizer ta are positioned at an end surface distal anterior of the central body. The third oxidant flow path and the first annular flow path of oxidant 139 and the second annular flow path of oxidizer 149 are in fluid coupling with the oxidizer inlet 111 (Fig. 10 3). An embodiment of the liner 103 is shown in detail in Figs. 6, 7 and 7A. The sidewall 105 of the liner 103 includes a plurality of cooling holes ment 171. Each cooling hole 171 extends through the side wall the 105 from the external surface 105A to the internal surface 105B of the side wall 105. 15

[0087] The liner 103, and in particular its sidewall 105, can be fabricated as a single monolithic component by additive manufacturing, e.g. par- tending from the front end 103F to the rear end 103A of the liner 103. Uti- by using additive manufacturing for the production of liner 103, the thickness of the pa- 105 side net can be made larger than manufacturing technologies 20 standards.

[0088] In some embodiments, the internal diameter of the liner, i.e. the cross-sectional diameter of the inner surface 105B of the wall 105, can be equal to or less than 300 mm, or equal to or less than 250 mm, for example equal to or less than 200 mm. The ratio between the thickness of the side wall 105 and the 25 internal cross-section diameter may be equal to or greater than 0.015, pre- probably equal to or greater than 0.02. For example, the ratio between the thickness of the wall and the internal diameter can be between 0.02 and 0.05, or between 0.2 and 0.04, or between 0.02 and 0.03.

[0089] If the liner has a non-circular internal cross-section, the above-mentioned 30 to ratio can be referred to the equivalent diameter defined as follows: -22- 4th O where S is the cross-sectional area of ​​the hot gas path in the liner.

[0090] In some embodiments, particularly for large liners, ni, which can be difficult to produce in a single manufacturing step 5 additive due to the size of the available additive manufacturing machines, the liner 103, and in particular its sidewall 105, can be manufactured in single ring-shaped portions or sections that are then welded to each other. In particular, the liner can be formed by producing individual ring portions by manufacturing additive and then welding the portions together. For example, the portions at 10 ring can be joined or coupled to each other by beam welding electrons.

[0091] Each ring portion represents a part of the axial development of the liner and extends in a circular fashion around the BB axis of the liner. Each part can be delimited by planes orthogonal to the BB axis of the liner. Once the 15 individual ring portions of the liner by additive manufacturing, they are aligne- neat with each other in the axial direction and welded peripherally along the edges rings of two consecutive portions abutting each other.

[0092] In some embodiments, the perforated intermediate section of the wall lateral 105 can be manufactured in a single piece by additive manufacturing, 20 and only the unperforated end sections of wall 105, which form the end front end 103F and rear end 103A, can be fabricated in stages of ma- additive manufacturing separated and welded to the perforated central or intermediate portion of the wall 105.

[0093] In some embodiments, the cooling holes are generated me- 25 diante additive manufacturing. This makes the manufacturing process faster. However, in other embodiments, some or all of the cooling holes may not be formed by drilling after the liner 103 has been fabricated me- during additive manufacturing. If the liner is made up of a plurality of ring-shaped portions welded to each other, cooling holes can be machined in each 30 each portion before welding or after welding the portions with each other -23- 𝐷𝑒𝑞 the other. The cooling holes can be machined by electro- rosine oxide dioxide (EDM).

[0094] In the embodiment of Figs. 6, 7, 7A, the cooling holes 171 are distributed in annular arrays of cooling holes 171, spaced in 5 sequence from each other from the front end 103F to the rear end 103A of the liner 103. Each annular array of cooling holes is positioned in cor- correspondence of a bridge 173, which connects two ring panels 175 arranged sequentially cutatively of the side wall 105 of the liner 103.

[0095] In some embodiments, each array of cooling holes 10 171 is associated with one or more lips or protrusions 177, which protrude from the surface internal of the lateral wall 105 and extend in an anterior to posterior direction inside the wall 105 of the liner 103. In the embodiment shown in the Figs. 7, 7A, each lip 177 has a ring shape and extends along the entire circumference of the inner surface of the side wall 105. Each lip 177 15 forms a respective annular slot which forms a guide for a cooling fluid chin entering the combustion chamber 7.1 through the cooling holes 171. The lips 177 are oriented so as to transmit to the cooling fluid to a velocity component tangent to the internal surface of the side wall, that is, oriented in an anterior to posterior direction within the chamber 20 combustion 7.1. Each lip 177 forms a ring-shaped empty space 179 in front to the respective annular array of cooling holes 171.

[0096] In the preferred embodiments, the lips 177 are generated by additive manufacturing during the formation of the sidewall 105 and form, per- so, a monolithic body. If the side wall 105 is manufactured by producing 25 individual ring portions which are then welded to each other, each Each portion is manufactured using additive manufacturing, the respective lips 177 forming a monolithic integral body with the ring portion of wall 105.

[0097] The liner may further comprise dilution holes 181, which extend from the- the outer surface to the inner surface of the side wall 105. The dilution holes 30 ne 181 can be distributed in various ways along the length of the wall 105 of the liner 103, to optimize fuel combustion and combustion gas flow -24- combustion along the liner 103. The distribution of the dilution holes illustrated in the drawing gno is purely illustrative.

[0098] In some embodiments the dilution holes 181 may be ge- blackened in the wall 105 of the liner by additive manufacturing, i.e. during the 5 additive manufacturing process that generates the liner 103 or part of it. In other forms of realization, the 181 dilution holes can be added once the liner 103, or a ring portion thereof, was generated by additive manufacturing. for example, the 181 dilution holes can be machined by electro- electroerosion machining (EDM). 10

[0099] The liner shown in Figs. 6, 7, 7A can be fabricated in a single piece by additive manufacturing starting from the front end 103F and arriving going to the rear end 103A. The cooling holes 171 and the dilution holes 181 are formed during the additive manufacturing process, along with the lips 177. 15

[0100] The liner 103 may also include one or more additional holes in its wall. 105 side tee, for connecting crossfire tubes and / or sensors, transducers and other Useful tools for controlling the combustion process. These additional holes are not shown.

[0101] At the end of the additive manufacturing process, the liner 103 is completely 20 tea size.

[0102] In other embodiments, the cooling holes 171 and / or the di- 181 can be machined into the wall 105 after forming of the latter.

[0103] If the size of the liner requires it, the wall 105 can be fabricated 25 forming separately by additive manufacturing two or more ring-shaped portions of the wall 105 in separate processes. The ring portions can then be welded together to form the liner 103. Each ring portion is fabricated monolithically with their respective lips 177. The cooling holes 171 and / or the cooling ports diffusion 181 can be formed by additive manufacturing in each port 30 ring tion of the side wall 105, or can be machined -25- inside them after the manufacturing of the ring portion, before or after welding turation of the ring portions.

[0104] Figs. 8 and 9 illustrate one embodiment of the transition piece. 113. In this embodiment, the transition piece 113 comprises a con- 5 internal duct 201 extending in an anterior to posterior direction from one end upstream, or front end, labeled 201F, at one end downstream, or extrem- rear 201A. The internal duct 201 forms a hot gas path 207 that extends from the liner 103 to the stationary nozzles 53, where the flow path begins expander expansion 3. The internal duct 201 has an internal surface 201B 10 facing the hot gas path, and an external surface 201C.

[0105] The outer surface 201C of the internal duct 201 faces a con- external duct 205, extending from one end to the upstream, or posterior end 205F, at a downstream end, or rear end 205A. The external duct 205 surrounds the internal duct 201 and has an internal surface 205B facing the 15 internal duct 201, and an external surface 205C facing the rear plenum 131.

[0106] The cooling ring 113A is formed between the inner surface 205B of the external duct 205 and the external surface 201C of the internal duct 201.

[0107] The cooling ring 113A may be in fluid coupling with 20 the hot gas path 207 through one or more effusion cooling holes 209. Each effusion cooling hole 209 extends through the thickness of the internal duct 201 from its outer surface to the inner surface.

[0108] In some embodiments, the inner conduit 201 and the outer conduit 201 no 205 are manufactured by additive manufacturing as a single monoblock 25 lithic, in the same 3D printing process. The effusion cooling holes po- can be manufactured by additive manufacturing during the generation process tion of the internal duct 201 and the external duct 205.

[0109] The downstream end, i.e. the rear end 201A of the in- internal 201 and the downstream end, or rear end 205A of the external conduit 205, 30 can be coupled to each other by means of a flange 211 surrounding the -26- hot gas path and closes one downstream end of the cooling ring 113A. If the external duct 205 and the internal duct 201 are manufactured by additive manufacturing in the same process, with internal and external conduits that cre- simultaneously from one end to the other end, the manufacturing process 5 additive cation can start from flange 2011 and continue from the rear end 201A and 205A of the internal duct 201 and the external duct 205 towards the end front 201F and 205F of the internal duct 201 and of the external duct 205, respectively During the additive manufacturing process, in the internal duct 201 ven- effusion cooling holes 209 are also generated. 10

[0110] Therefore, the internal duct 201, the external duct 205 and the flange 211 co- in this embodiment they constitute a monolithic structure manufactured by during additive manufacturing in the same additive manufacturing sequence.

[0111] According to a different embodiment, the external duct 205 is formed made from a first shell and a second shell, which are manufactured separately 15 from each other and separately from the internal duct 201, and connected to each other by welding, and further connected by welding to the internal duct 201.

[0112] In this embodiment, the internal conduit 201 may be fabricated produced in a single additive manufacturing sequence. The flange 211 can be manufactured 20 bricata during this first additive manufacturing sequence monolithically with the internal duct. The resulting transition piece component generated in this Additive manufacturing sequence is shown in an axonometric section view in Fig. 10, while Fig. 11 shows a complete axonometric view of the entire transition piece component. 25

[0113] In a modified embodiment, the flange 211 may be fabricated ta separately from the internal duct 201 and welded to it subsequently, for example by electron beam welding.

[0114] The effusion cooling holes 209 may be fabricated by you additive manufacturing during this production step. 30

[0115] The external duct 205 is fabricated by additive manufacturing in two -27- separate passages, each passage producing a portion of the outer duct 205 in the form of an external shell. Fig. 12 illustrates one of these shells, the other being do substantially symmetrical. In Fig. 13 the two shells, labeled 205X ​​and 205Y, are welded to each other along a weld line 206. Although in Fig. 5 13 the external duct 205 produced by welding the two shells 205X ​​and 205Y is shown in isolation, it should be understood that the two shells 205X ​​and 205Y are actually you welded to each other after being arranged around the internal duct 201. The rear end of each shell 205X, 205Y is welded to flange 211.

[0116] If the transition piece 113 is produced by assembling three separate pieces 10 201, 205X, 205Y manufactured separately, the effusion cooling holes 209 can be machined into the internal duct 201 before welding the two shells 205X, 205Y around them.

[0117] Producing the transition piece 113 by additive manufacturing as described above, the internal conduit 201 and / or the external conduit 205 may have a 15 thickness greater than that usually achievable with the manufacturing technique of the current technique. In particular, it is possible to obtain a higher ratio between the thickness of the duct 201, 205 and the equivalent diameter of the hot gas path. In some embodiments, the ratio of the thickness of the internal duct 201 and / or of the external duct 205 and the equivalent diameter of the hot gas path can be 20 re equal to or greater than 0.020, preferably equal to or greater than 0.025 long the entire extension of the transition piece. The equivalent diameter of the transition piece situation can be defined as 4th O where S is the cross-sectional area of ​​the hot gas path. 25

[0118] Exemplary embodiments have been described and illustrated above. in the attached drawings. Those skilled in the art will understand that they may be affixed various changes, omissions and additions to what is expressly described herein, sen- to go beyond the scope of the invention as defined in the following claims. -28- 𝐷𝑒𝑞

Claims

CLAIMS 1. A burner for a power-generating turbomachine, the burner comprising: a central body with an oxidizer duct extending along the axis of the burner and having at least one oxidizer outlet port; an intermediate annular wall, extending coaxially around the central body; wherein a first annular oxidizer flow path is formed between the central body and the intermediate annular wall; a fuel passage extending through the intermediate annular wall and having at least one fuel port; an outer annular wall surrounding the intermediate annular wall; wherein a second annular oxidizer flow path is formed between the intermediate annular wall and the outer annular wall.

2. The burner of claim 1, wherein the first annular flow path of oxidant is formed between an outer side surface of the central body and an inner side wall of the intermediate annular wall.

3. The burner of claim 1 or 2, wherein the second annular flow path of oxidant is formed between an outer sidewall of the intermediate annular wall and an inner sidewall of the outer annular wall.

4. The burner of any preceding claim, wherein the first annular oxidant flow path has a cross-sectional area that is less than a cross-sectional area of ​​the second annular oxidant flow path.

5. The burner of claim 4, wherein the cross-sectional area of ​​the first annular oxidant flow path is between 50% and -29Ufficio Mannucci srl 70%, preferably between 60% and 65% of the cross-sectional area of ​​the second oxidant flow path.

6. The burner of any preceding claim, further comprising a first vortex flow generator positioned in the first annular oxidizer flow path.

7. The burner of any preceding claim, further comprising a second vortex flow generator positioned in the second annular oxidizer flow path.

8. The burner of claims 6 and 7, wherein both the first vortex flow generator and the second vortex flow generator are respectively adapted to induce tangential motion in the same direction within both the first annular oxidant flow path and the second annular oxidant flow path.

9. The burner of claim 6 or 8, wherein the first vortex generator comprises a plurality of first inclined blades configured to impart tangential motion to an oxidizer stream in the first oxidizer flow path.

10. The burner of claim 7 or 8, wherein the second vortex generator comprises a plurality of second inclined blades configured to impart tangential motion to an oxidizer stream in the second oxidizer flow path.

11. The burner of claim 10, wherein at least one fuel supply conduit extends through at least one of said second inclined blades from the outer annular wall to the inner annular wall, the fuel supply conduit having an inlet end in fluid coupling with a fuel inlet plenum and an outlet end in coupling with the fuel passage extending through the intermediate annular wall.

12. The burner of any preceding claim, wherein -30Ufficio Mannucci srl at least one fuel port is positioned on a distal front surface of the intermediate annular wall.

13. The burner of claim 12, wherein at least one fuel port comprises a plurality of fuel ports arranged in a circular manner about the axis of the burner shaft.

14. The burner of any preceding claim, wherein the at least one oxidizer outlet port is positioned at a forward distal end surface of the central body.

15. The burner of claim 14, wherein the at least one oxidizer outlet port comprises a plurality of oxidizer outlet ports positioned at the forward distal end surface of the central body.

16. The burner of any preceding claim, wherein the burner is manufactured by additive manufacturing.

17. A combustor for a power-generating turbomachine, the combustor comprising: a liner; connected to said liner, at least one burner according to any preceding claim.

18. The combustor of claim 17, configured as a tubular combustor.

19. A power generating turbomachine, comprising: a casing; a rotor supported to rotate in the casing; a combustor, comprising a liner and at least one burner according to any of claims 1 to 16.

20. The power generating turbomachine of claim 19, wherein the combustor is a tubular combustor.