CN112189112A

CN112189112A - Burner nozzle

Info

Publication number: CN112189112A
Application number: CN201880093583.3A
Authority: CN
Inventors: O·I·林德洛夫; R·G·哈特维格; J·伦德伯格
Original assignee: Wartsila Moss AS
Current assignee: Wartsila Moss AS
Priority date: 2018-05-21
Filing date: 2018-05-21
Publication date: 2021-01-05
Anticipated expiration: 2038-05-21
Also published as: KR102390242B1; EP3797247A1; CN112189112B; KR20210013055A; EP3797247B1; FI3797247T3; WO2019223848A1

Abstract

The invention relates to a burner nozzle (10) for atomizing a liquid fuel with the aid of a compressed gas, the burner nozzle (10) comprising a first outlet (16) for the compressed gas and a second outlet (20) for the liquid fuel, the first outlet (16) having a central axis (18). The second outlet (20) is arranged rotationally symmetrically around the first outlet (16) with respect to the central axis (18), the first outlet (16) comprises an outwardly extending conical portion (22), and the burner nozzle (10) comprises a gas dispersion element (24), the gas dispersion element (24) being arranged at the central axis (18), spaced apart from the first outlet (16) in a direction away from the first outlet (16) and coaxial with the first outlet (16).

Description

Burner nozzle

Technical Field

The present invention relates to a burner nozzle for atomizing a liquid fuel with the aid of compressed gas according to the preamble of claim 1, which burner nozzle comprises a first outlet for compressed gas and a second outlet for liquid fuel, which outlet has a central axis.

Background

While the importance of environmental issues, particularly exhaust emissions, has increased, liquefied gases are gaining increasing attention as fuels for prime movers in marine vessels and other mobile and stationary power plants.

Liquefied gases, such as liquefied natural gas, are usually stored at extremely low temperatures and a portion of the gas is vaporized due to, for example, heat transfer from the surroundings, which is a so-called boil-off gas. It is undesirable to permit the boil-off gas to pass to the atmosphere. It is well known to burn excess gas to convert it into a component that is significantly less harmful to the environment.

Such liquefied gas tanks and fuel processing systems also require inerting of the space associated with the tank, piping, etc., for example, to perform maintenance work. It is well known to burn the gases present in the tank and its ancillary equipment to convert them into components of non-reactive gases (i.e., inert gases).

KR20150096540 discloses a method of combusting and providing an inert gas to fill a storage tank with an inert gas. As an example of a boil-off gas combustion device, reference is made to publication WO 00/47463 a 1.

Inert gas generators and boil-off gas combustion devices often require auxiliary burners configured to burn liquid fuel to support combustion of the diluted boil-off gas. A key component in combustors is the fuel nozzle. In order to ensure that the burner operates with optimum performance when burning, for example, diesel or light fuel oil, it is necessary to mix the air with the fuel in a suitable and controlled manner. In addition, in order to use the burners in various configurations, a large turndown ratio is required; that is, it is possible to maintain both the atomization level (i.e., ensure monodisperse and predictable spray) and the spray angle over a large output range.

The invention particularly relates to liquid fuel nozzles in which liquid fuel is atomized with the aid of a compressed gas, preferably air.

It is an object to provide a fuel nozzle for a combustor that provides better performance than known fuel nozzles.

Disclosure of Invention

The objects of the invention can be met substantially as disclosed in the independent claims and in the other claims describing more details of different embodiments of the invention.

According to an embodiment of the invention, a burner nozzle for atomizing a liquid fuel with the aid of a compressed gas comprises a first outlet for the compressed gas and a second outlet for the liquid fuel, the first outlet having a central axis. The second outlet is arranged rotationally symmetrically about the first outlet with respect to the central axis, the first outlet comprises an outwardly extending conical portion, and the burner nozzle comprises a gas dispersion element arranged at the central axis, spaced apart from and coaxial with the first outlet in a direction away from the first outlet.

According to an embodiment of the invention, the second outlet comprises an annular slit arranged coaxially with the first outlet.

According to an embodiment of the invention, the second outlet is arranged at an end of the first outlet in the axial direction.

According to an embodiment of the invention, the dispersion element is rotationally symmetric with respect to the central axis and arranged to extend in an axial direction.

According to an embodiment of the invention, the radial dimension of the dispersion element is arranged to increase with increasing distance from the first outlet.

According to an embodiment of the invention, the dispersion element is conical with its apex towards the first outlet.

According to an embodiment of the invention, the burner nozzle has a body assembly comprising a first body portion and a second body portion, wherein the first body portion comprises: a gas flow passage arranged to extend through the first body portion along the central axis from a first end to a second end of the first body portion, the second end of the gas flow passage constituting the first outlet; and an outer surface rotationally symmetric with respect to the central axis, and wherein the second body portion comprises: a sleeve segment extending axially over an outer surface of the first body portion, wherein the sleeve segment of the second body portion and the outer surface of the first body portion form an annular space therebetween, the annular space forming a fuel conduit and terminating at the second outlet.

According to an embodiment of the invention, the first and second body parts are provided with means for aligning and retaining the first and second body parts in a coaxial relationship with each other.

According to an embodiment of the invention, the first body part comprises a first flange part arranged at the first end of the first body part and the second body part comprises a second flange part at a first end of the second body part, and the first and second flange parts are provided with a mating form configured to align and hold the first and second body parts in a coaxial relationship with each other.

According to an embodiment of the invention, the gas flow channel comprises at a first end of the gas flow channel a flow channel section converging towards the second end followed by a flow channel extending towards the second end of the gas flow channel.

According to an embodiment of the invention, the dispersion element is fixed to the first body part.

According to an embodiment of the invention, the dispersion element is fixed to the second body portion.

With the present invention, a liquid fuel such as diesel fuel is atomized using a compressed gas (typically air). This provides the possibility of using a reduced fuel supply pressure. In addition, a more stable monodisperse spray is obtained over a large fuel flow range.

By means of the invention, the nozzle can be modularized, so that for example one second body part can be used in combination with differently formed first body parts. In this way, the capacity of the fuel nozzle can be changed by changing only the first body portion of the fuel nozzle.

The exemplary embodiments of the invention set forth in this patent application should not be construed as limiting the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation, not excluding the presence of also unrecited features. The fuel nozzle according to the present invention may be used in any practical combustor application other than that described herein for atomizing and combusting liquid fuel with the aid of compressed air. The features set forth in the dependent claims can be freely combined with one another, unless explicitly stated otherwise. The novel features believed characteristic of the invention are set forth with particularity in the appended claims.

Drawings

The invention will be described below with reference to the appended schematic exemplary drawings, in which:

figure 1 illustrates a burner nozzle according to an embodiment of the invention,

FIG. 2 illustrates a first body portion of a combustor nozzle, in accordance with embodiments of the present invention, and

fig. 3 illustrates a second body portion of a combustor nozzle according to an embodiment of the present invention.

Detailed Description

Fig. 1 schematically depicts a burner nozzle 10 for atomizing a liquid fuel with the aid of compressed gas according to an embodiment of the present invention. The nozzle is configured to be attached to a separate burner body or nozzle tube (not shown) in the burner body, through which liquid fuel and compressed air (advantageously air) can be introduced into the nozzle 10, as depicted by the

respective arrows

12, 14, the

arrows

12, 14 also showing the general flow direction of the fluid. Fuel and compressed air are then injected from the nozzle 10 to atomize the fuel and thereafter combust the fuel. The burner nozzle 10 is a two-fluid atomizer. The nozzle utilizes a so-called "Air Centre Liquid Ring" in which a thin annular Liquid film is formed and the exiting thin annular Liquid film is atomized using expanding Air exiting the central outlet.

The burner nozzle 10 comprises a first outlet 16 for compressed gas. The first outlet is arranged coaxially in the central axis 18 of the nozzle 10. The compressed gas is used to assist in the atomization of the liquid fuel introduced via the nozzle 10. Thus, the nozzle 10 is further provided with a second outlet 20 for the liquid fuel, the second outlet 20 being arranged rotationally symmetrically about the first outlet 16 with respect to the central axis 18. In the embodiment of fig. 1, the second outlet 20 is an annular slit 20 arranged coaxially with the first outlet. It is also possible within the scope of the invention that the second outlet 20 comprises, instead of a completely continuous slit, a plurality of partial slits separated by narrow radial support projections in any of a plurality of body portions (not shown). The purpose of the slits is to provide an annular liquid fuel film that initially flows out of the nozzle 10 and is then influenced by the flow of compressed gas.

The first outlet 16 comprises an outwardly extending conical portion 22, by means of which conical portion 22 the flow of compressed gas is widened and directed to comprise a radial velocity component. In other words, the radial cross-sectional dimension of the conical portion 22 is arranged to increase towards the actual outlet. In this way, the flow of compressed gas and the annular membrane of liquid fuel coincide with each other, and the fuel membrane is atomized into droplets and/or mist. The fuel burner 10 also includes a gas distributing element 24, the gas distributing element 24 being disposed at the central axis 18, spaced apart from and coaxial with the first outlet 16 in a direction away from the first outlet 16. The gas dispersion member 24 is formed to further direct the flow of compressed gas into the form of a hollow cone, which facilitates the formation of a conical flow pattern of liquid fuel droplets and/or mist. The dispersion element 24 is rotationally symmetrical with respect to the central axis 18. The radial cross-sectional dimension of the dispersion element 24 is arranged to increase with increasing distance from the first outlet 16. More precisely, the dispersion element in fig. 1 is conical, the apex of which is directed towards the first outlet 16. This will set the fuel spray to the desired angle and maintain that angle throughout the flow range of the nozzle and ensure that the fuel spray is monodisperse over a large range, further helping to maintain an optimum air/fuel mixture.

As can be seen in fig. 1, the first outlet 16 and the second outlet 20 are arranged to open at a common axial position, i.e. the second outlet 20 is arranged axially at an end of the first outlet 16. At the position shown in fig. 1 or when the central axis 18 is vertically oriented, this means that the first outlet 16 and the second outlet 20 are arranged to open at the same level.

The combustor nozzle includes a body assembly 26 having various portions. The body assembly 26 is described in more detail with reference to fig. 2 and 3. The assembly includes a first body portion 30 shown in fig. 2 and a second body portion 32 shown in fig. 3. As can be seen in fig. 1, the first and second body portions form the burner nozzle 10 when the first and second body portions are assembled such that the second body portion partially surrounds the first body portion. Fig. 2A shows a side view of the first body portion 30, such that the right side shows a cross-sectional view of the first body portion and the left side shows a front view of the first body portion. Fig. 2B shows the first main body portion in the direction B of fig. 2A (i.e., from above in the drawing). Fig. 3A shows a side view of the second body part, such that the right side shows a cross-sectional view of the second body part and the left side shows a front view of the second body part. Fig. 3B shows the second body portion in the direction B of fig. 3A.

The first body portion 30 comprises a gas flow passage 34, the gas flow passage 34 being arranged to extend through the first body portion along the central axis 18 from the first end 30' (i.e. the inlet end of the burner nozzle) to the second end 30 "of the burner nozzle. The gas flow channel 34 has a particular form such that the cross-sectional area of the channel 34 first gradually (shown in dashed lines in fig. 2A) or gradually shrinks from the first end such that a local constriction 36 is present in the channel 34. After the narrowed portion 36, in the flow direction of the gas, the second end of the gas flow channel constitutes a first outlet 16 which has a surface 16' in the first body portion 30 which is rotationally symmetrical with respect to the central axis. The outer surface is rotationally symmetrical, advantageously conical in shape, the cross-sectional dimension of which increases with increasing distance from the local stenosis 36.

The first and

second body portions

30, 32 are provided with means 40 for aligning and retaining the first and second body portions in coaxial relationship with one another. For this purpose, the first body portion 30 is provided with a flange portion 38 at its first end 30'. The first body portion 30 includes a first flange portion 38 disposed at the first end 30' of the first body portion 30. The first flange portion 38 is provided with one or more alignment protrusions 40. The projections 40 may have different forms. In the embodiment of fig. 1 and 2, the protrusion 40 comprises two or more pins or the like arranged to extend from the otherwise generally planar surface of the flange portion 38 towards the second end 30' of the first body portion 30. The projection may also be an annular ring projection, for example. The means 40 for aligning and retaining the first and second body portions in coaxial relationship with one another may also be configured in the particular form of the flange portion 42 to provide an alignment effect by that form. In fig. 1, it can be seen how the first and second body portions align with each other when the pin 40 is located within the cavity 40' and the

flange portions

38, 42 are facing closely towards each other.

The first body portion 30 is provided with a generally inwardly tapered outer surface 44, the outer surface 44 extending from the first flange portion 36 in a direction from the first end 30' to the second end 30 ". More specifically, in the drawings, the outer surface is in the form of a frustum. The outer surface 44 partially bounds the fuel conduit formed between the first and

second body portions

30, 32.

The first body portion 30 is provided with an axial opening 50 disposed in the first flange portion 38. The opening is disposed at a location radially outward of the outer surface 44 of the first body portion 30 to open into an annular fuel conduit formed between the first and

second body portions

30, 32 when the first and

second body portions

30, 32 are assembled as intended. The opening 50 is formed in the first flange portion 38 such that there is in effect an annular opening around the outer surface 44.

Correspondingly, the second body portion 32 is provided with a second flange portion 42 at the first end 30' of the second body portion 32. The first and

second flange portions

38, 42 are provided with mating forms configured to align and retain the first and

second body portions

30, 32 in a coaxial relationship with one another. Thus, the second flange portion includes one or more notches 40 ', the notches 40' being spaced apart and shaped to mate with the protrusions in the first flange portion 38 in the first body portion 30. In the embodiment of fig. 1 and 3, the recess 40 includes two or more cylindrical cavities or the like disposed in the otherwise generally planar surface of the flange portion 42.

The second body portion 32 also includes a sleeve segment 46 extending axially from the second flange portion 42 of the second body portion 32. The sleeve segment has a generally cylindrical outer surface with rounded edges at the second end 30 ". The inner surface 48 of the second body portion is a generally inwardly tapered circular surface that extends from the second flange portion 42 in a direction from the first end 30' to the second end 30 ". More specifically, in the drawings, the inner surface 48 is in the form of a frustum. The angle of the frustum of the second body portion 32 relative to the central axis 18 is greater than the angle of the frustum of the first body portion 30.

The sleeve segment 46 of the second body portion 32 is above the outer surface 44 of the first body portion 30 when assembled to the first body portion 30 as shown in fig. 1. The second body portion 32 has an opening 52 radially inward of the flange portion 42 and the collar 46, and the first body portion 30 can be assembled into the opening 52 such that the first flange portion 36 axially abuts the second flange portion 42. When the first and

second body portions

30, 32 are assembled together as shown in fig. 1, the sleeve section 48 of the second body portion 32 and the outer surface 44 of the first body portion 30 form an annular space 54 therebetween that connects the axial opening 50 in the first body portion 30 to the second outlet 20 of the nozzle 10 and forms a fuel conduit formed therebetween.

As can be seen in fig. 1 and 2, the dispersion element 24 is supported from the nozzle by means of an axially oriented rod or the like 28. There are three rotationally symmetrically arranged rods 28 fixed to the dispersion element 24, the rods 28 being arranged in the first body part. Naturally, the number of rods 28 may vary according to the circumstances. It is also contemplated that the dispersion element 24 may be supported by a rod from the second body portion 46. However, it is more advantageous to support the dispersion element from the first body portion 30. This is because: when only gas, and not liquid fuel, is required to flow through the stem 28, the stem 28 has less interference with fuel film formation. The dispersion element 24 advantageously has a circular base when in the form of a cone. However, the benefits of the present invention can be obtained (at least to some extent) by using pyramidal dispersing elements that are polygonal in shape with more than 5 regular sides (pentagons). In the figures, the dispersion element 24 is depicted as a hollow cone.

While the invention has been described herein by way of examples in connection with what are at present considered to be the most preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features and several other applications included within the scope of the invention as defined in the appended claims. When the combination of details mentioned in connection with any of the above embodiments with another embodiment is technically feasible, these details can be used in connection with the other embodiment.

Claims

1. A burner nozzle (10) for atomizing a liquid fuel with the aid of compressed gas, the burner nozzle (10) comprising a first outlet (16) for compressed gas and a second outlet (20) for liquid fuel, the first outlet (16) having a central axis (18), characterized in that the second outlet (20) is arranged rotationally symmetrically about the first outlet (16) with respect to the central axis (18), the first outlet (16) comprising an outwardly extending conical portion (22), and the burner nozzle (10) comprising a gas dispersion element (24), the gas dispersion element (24) being arranged at the central axis (18), spaced apart from the first outlet (16) in a direction away from the first outlet (16) and coaxial with the first outlet (16).

2. A burner nozzle (10) according to claim 1, characterized in that the second outlet (20) comprises an annular slit (20) arranged coaxially with the first outlet (16).

3. A burner nozzle (10) according to claim 1 or 2, characterized in that the second outlet (20) is arranged at the end of the first outlet (16) in axial direction.

4. A burner nozzle (10) according to claim 1, characterized in that the dispersion element (24) is rotationally symmetric with respect to the centre axis (18) and arranged to extend in an axial direction.

5. A burner nozzle (10) according to claim 4, characterized in that the radial dimension of the dispersion element (24) is arranged to increase with increasing distance from the first outlet (16).

6. A burner nozzle (10) according to claim 5, characterized in that the dispersion element (24) is conical with its apex towards the first outlet (16).

7. The combustor nozzle (10) of claim 1, wherein the combustor nozzle (10) has a body assembly including a first body portion (30) and a second body portion (32), wherein the first body portion comprises:

a gas flow passage (34) arranged to extend through the first body portion (30) along the central axis (18) from a first end (30') to a second end (30 ") of the first body portion (30), the second end of the gas flow passage (34) constituting the first outlet (16); and

an outer surface (44) that is rotationally symmetrical with respect to the central axis (18), and

the second body portion (32) includes:

a sleeve segment (46) extending axially over the outer surface of the first body portion (30), wherein the sleeve segment (46) of the second body portion (32) and the outer surface (44) of the first body portion (30) form an annular space therebetween, the annular space forming a fuel conduit and terminating at the second outlet (20).

8. A burner nozzle (10) according to claim 7, wherein the first and second body portions (30, 32) are provided with means for aligning and retaining the first and second body portions (30, 32) in a coaxial relationship with one another.

9. The combustor nozzle (10) of claim 8, characterized in that the first body portion (30) includes a first flange portion (38) disposed at the first end of the first body portion (30) and the second body portion (32) includes a second flange portion (38) at a first end of the second body portion (32), and the first and second flange portions (38, 42) are provided with a mating form configured to align and retain the first and second body portions (30, 32) in a coaxial relationship with one another.

10. A burner nozzle (10) according to claim 7, characterized in that the gas flow channel (34) comprises at a first end of the gas flow channel a flow channel section converging (36) towards the second end followed by a flow channel extending towards the second end of the gas flow channel (34).

11. A burner nozzle (10) according to claims 1 and 7, characterized in that the dispersion element (24) is fixed to the first main body portion (30).

12. A burner nozzle (10) according to claims 1 and 7, characterized in that the dispersion element (24) is fixed to the second main body portion (32).