CN117043514A

CN117043514A - Fluid burner head and use of a fluid burner head

Info

Publication number: CN117043514A
Application number: CN202280020195.9A
Authority: CN
Inventors: L·斯凯特乔根森
Original assignee: Alfa Laval Corporate AB
Current assignee: Alfa Laval Corporate AB
Priority date: 2021-03-24
Filing date: 2022-03-16
Publication date: 2023-11-10
Also published as: TW202248570A; JP2024508005A; TWI868435B; EP4314652A1; JP7634707B2; KR20230156106A; EP4063731A1; WO2022200150A1

Abstract

A fluid burner head (9) is provided for a fluid burning unit (1) and the use of the fluid burner head (9) in the fluid burning unit (1). The fluid burner head (9) includes a body (11) which in turn includes a hollow tube (13) for conveying the fluid to be burned into the combustion chamber (5) and an at least partially closed tube (13) The upper end (25) of the cap (15). The wall (17) of the tube (13) includes multiple rows (29) of holes (27) extending around the longitudinal center axis (C) of the fluid burner head (9). The holes (27) allow the fluid to be burned to flow from the inside (49) to the outside (51) of the tube (13). The fluid burner head (9) is characterized in that it also includes an annular first protrusion (39) extending around the longitudinal center axis (C) of the fluid burner head (9). The first protrusion (39) extends from the outer surface (43) of the body (11) upwardly relative to the longitudinal center axis (9) of the fluid burner head (9) above the holes (27) of the uppermost row (29a) of the tube (13). C) protrudes obliquely at an angle α, where 0<α<90 degrees.

Description

Fluid burner head and use of a fluid burner head

Technical Field

The present invention relates to a fluid burner head for a fluid combustion unit and its design. The invention also relates to the use of such a fluid burner head in a fluid combustion unit for burning boil-off gas from a fuel tank on a ship.

Background

In different situations, a combustion fluid, such as a gas or a mixture of gas and liquid, may be required. For example, the gas combustion unit is typically mounted on an LNG carrier (i.e., a tank vessel arranged to transport Liquefied Natural Gas (LNG)). The tank contains LNG having a vaporization temperature of-160 degrees celsius at atmospheric pressure. Even if these tanks are insulated, some vaporization of LNG will inevitably occur and form so-called boil-off gas. The boil-off gas increases the pressure in the tank and must be vented from the tank for safety. The boil-off gas removed from the tank may be re-liquefied and returned to the tank for use as fuel on LNG carriers or for combustion by means of a gas combustion unit.

The gas combustion unit may typically comprise a gas burner head extending into the combustion chamber. The gas to be combusted is fed via a gas burner head to a combustion chamber, where it is ignited and burned. The known gas burner head comprises a perforated tube with an end closed by a cap. The gas is conveyed through the tube and through the perforations of the tube into the combustion chamber where combustion takes place in the flame. When the gas pressure is relatively high, the gas will be fed through the perforations at a high velocity, which will cause the flame to be at some distance from the gas burner head. Furthermore, the gas flow inside the tube will cool the gas burner head. As a result, the temperature of the gas burner head will remain sufficiently low so as to avoid damage thereto. However, when the gas pressure is relatively low, the gas will be fed through the perforations at a low velocity, which will result in a flame closer to the gas burner head. Furthermore, the cooling of the gas burner head by the gas flow inside the tube will be reduced. This can lead to very high temperatures in the gas burner head and damage to the gas burner head (typically in the region close to the closed end of the tube).

Disclosure of Invention

It is an object of the present invention to provide a fluid burner head and a use of a fluid burner head, which at least partly solve the above problems. The basic idea of the invention is to provide the fluid burner head with means for forcing the fluid to be combusted (and thus the combustion flame) further away from the fluid burner head. The fluid burner head for achieving the above object and the use of the fluid burner head are defined in the appended claims and discussed below.

The fluid burner head for a fluid combustion unit according to the present invention comprises a body. The body includes a hollow tube or pipe for delivering fluid to be combusted into the combustion chamber and a cap at least partially closing the upper end of the tube. The tube also includes a lower end for receiving fluid in the tube (i.e., in the interior of the tube). The wall of the tube includes a plurality of rows of holes that extend about the longitudinal central axis of the fluid burner head. The holes allow the fluid to be combusted to flow from the inside to the outside of the tube (i.e., through the wall of the tube). The fluid-burner head is characterized in that it further comprises an annular first projection or protuberance extending around the longitudinal central axis of the fluid-burner head. The first protrusion protrudes obliquely at an angle a from the outer surface of the body above the uppermost row of holes of the tube and in a direction away from the lower end of the tube (i.e. upwards) with respect to the longitudinal central axis of the fluid burner head, wherein 0< a <90 degrees. The uppermost row of holes is the row of holes arranged closest to the cap.

The first protrusion may include opposite first and second edges. The first and second edges may be annular and extend along each other. The first protrusion may be directly or indirectly engaged with the body at and along the first edge, and the second edge may be free.

Herein, "combustion" and "incineration" and variants thereof are used and are intended to have the same meaning.

The fluid may be a gas or a mixture of gas and liquid. As an example, the fluid may be a boil-off gas from an LNG tank, such as methane or a mixture of methane and nitrogen.

The tube may comprise a mesh formed as a cylinder.

The tube may be a perforated tube and the opening may be a perforation of the tube.

The tube may be elongated, have any suitable wall thickness, and have any suitable cross-section (such as circular, oval, or polygonal).

The tube may be made of any suitable material, such as metal, for example carbon steel, stainless steel or aluminum.

The longitudinal central axis of the fluid burner head may coincide with the longitudinal central axis of the tube.

By multi-row is meant herein two or more rows.

The holes, openings, apertures, or perforations of the tubes may or may not all be the same size and/or shape, and they may be of any suitable size and shape (such as circular, oval, or polygonal). Furthermore, the holes may or may not be equidistantly arranged.

"annular" need not mean a circular longitudinal extension, but may mean any closed longitudinal extension, such as an elliptical or polygonal extension.

Herein, "upper", "uppermost", "lower", "lowermost", "above", "below" and the like are references to the fluid-incinerator head when this is oriented for its normal use condition. Furthermore, "uppermost"/"lowermost" means disposed furthest/closest to the ground or surface on which the fluid combustion unit including the fluid burner head is disposed.

As described above, the cap at least partially closes the upper end of the tube. Here, an upper end that is only partially closed may for example mean that it is possible for gas to travel from inside the tube to the outside thereof, possibly through an opening in the cap or between the tube and the cap.

The first projection may or may not have a uniform cross-section (e.g., constant width and/or thickness) along its longitudinal extension. As an example, the first protrusion may be formed as a skirt or flange. The first projection may be considered intermittent if the width and thickness are zero along one or more portions of the longitudinal extension.

The first projection is arranged to force fluid to be combusted away from the fluid-incinerator head to reduce the temperature of the fluid-incinerator head and thereby reduce the risk of damage to the fluid-incinerator head, also when fluid is fed through the bore of the tube at a relatively low rate.

The tube and cap may be integrally formed. However, according to one embodiment of the present invention, the tube and the cap are formed separately. Thus, the tube and cap can be replaced independently of each other if desired.

The tube and cap may be made of the same material. However, according to one embodiment of the invention, the cap and tube are made of different materials. This may allow for a more flexible construction of the fluid incinerator head. The cap may be made of any suitable material, such as refractory concrete or metal, for example carbon steel, stainless steel or aluminium.

The first protrusion may be arranged anywhere between the uppermost row of apertures of the tube and the upper end of the fluid burner head. However, according to one embodiment of the invention, the first protrusion protrudes from the outer surface of the body at the boundary between the tube and the cap. With the first tab not in place, the temperature locally at the boundary between the tube and the cap tends to be relatively high. Thus, by arranging the first protrusion at the tube-cap boundary, the risk of damage to the fluid burner head may be minimized.

The fluid incinerator head may be configured such that the tube and the first protrusion are formed separately. Thus, when the first tab wears out, it can be replaced with a new one without having to discard the tube and possible cap.

The tube may have a varying cross-section along its longitudinal central axis. However, according to one embodiment of the invention, the upper portion of the tube comprising the bore has a substantially uniform cross-section along the longitudinal centre axis of the fluid burner head. This may facilitate production of the fluid burner head.

The fluid incinerator head may further comprise an annular support extending around a longitudinal central axis of the fluid incinerator head. The support may be connected to the first protrusion and engaged with the body of the fluid incinerator head to secure the first protrusion to the body. Such a design may facilitate the placement of the first protrusion on the body. Just like the first projection, the support may or may not have a uniform cross-section along its longitudinal extension, and may be continuous or intermittent.

The fluid incinerator head may further comprise an annular second projection extending around a longitudinal central axis of the fluid incinerator head. The second protrusion may protrude from the outer surface of the body between the uppermost row of holes of the tube and the first protrusion. The first protrusion may or may not protrude beyond the second protrusion. The second protrusion may help to force the fluid to be combusted away from the fluid-burner head to further reduce the temperature of the fluid-burner head and thereby further reduce the risk of damage to the fluid-burner head, as well when the fluid is fed through the bore of the tube at a relatively low rate.

The second protrusion may protrude from the outer surface of the tube to locally shield the tube in areas where the temperature of the tube would otherwise be relatively high. Thereby minimizing the risk of damage to the tubing.

As described above, the fluid incinerator head may comprise an annular support extending about a longitudinal central axis of the fluid incinerator head. The support may be connected to both the first and second protrusions and engage with the body of the fluid-incinerator head to secure the first and second protrusions to the body.

Whether the support is connected only to the first projection or also to the second projection, it can be engaged with the body in a different manner. As an example, it may be screwed onto the body with a tight fit so as to be held in place by friction. However, according to one embodiment of the invention, the support is sandwiched between the cap and the tube. Thereby, an accurate positioning of the first projection and possibly also of the second projection may be allowed, together with a reliable engagement between the support and the body of the fluid burner head.

The cap may be designed in many different ways. According to one embodiment of the invention, it comprises an upper part and a bottom part, wherein the bottom part protrudes into the tube. Thus, a safe and accurate engagement between the cap and the tube may be allowed.

The bottom portion of the cap may include a portion that tapers in a direction away from the upper portion of the cap. For example, the bottom portion may be tapered (and possibly frustoconical). This may result in a decrease in the flow area inside the tube perpendicular to the longitudinal central axis of the tube in a direction towards the cap (i.e. towards the upper end of the tube). In turn, this may result in an increase in fluid flow velocity inside the tube in a direction towards the cap (i.e. towards the upper end of the tube). Thus, the design may allow forcing the fluid supplied through the upper bore of the tube (and thus the combustion flame) farther from the fluid burner head. Thereby, it may be allowed to further reduce the temperature of the fluid burner head and the risk of damage to the fluid burner head, especially when the fluid is fed through the tube at a relatively low pressure.

The fluid burner head may be designed such that the outer periphery (circumference) of the upper portion of the cap is larger than the inner periphery of the tube. Thus, the upper portion of the cap is prevented from being received in the tube, which may allow for accurate and safe engagement between the cap and the tube.

The fluid burner head according to the invention can be used in a fluid combustion unit for burning boil-off gas from a fuel tank on a ship.

The advantages discussed above for the different embodiments of the fluid burner head according to the invention are naturally transferable to the different embodiments of the use according to the invention.

Still other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and from the accompanying drawings.

Drawings

The invention will now be described in more detail with reference to the attached schematic drawings in which

Figure 1 schematically shows a cross section of a fluid combustion unit,

figure 2 is a schematic perspective view of a fluid burner head of the fluid combustion unit of figure 1,

figure 3 is a schematic side view of the fluid incinerator head of figure 2,

figure 4 is a schematic cross-section of the fluid incinerator head of figure 2,

figure 5 is an enlarged view of a portion of the cross-section of figure 4,

figure 6a is a schematic side view of the arrangement of the fluid incinerator head in figure 2,

FIG. 6b is a schematic top view of the arrangement in FIG. 6a, an

Fig. 6c is a schematic cross-section of the arrangement in fig. 6 a.

Detailed Description

In fig. 1a fluid combustion unit 1, more particularly a gas combustion unit, is shown. The fluid or gas combustion unit 1 is arranged on a ship (not shown), more particularly on an LNG carrier, for incinerating boil-off gas from one or more LNG tanks of the ship. The fluid combustion unit 1 comprises a fluid burner system 3, an air supply system (not shown), a combustion chamber 5 and a stack 7. The boil-off gas from the LNG tank is fed to the fluid burner system 3 and further into the combustion chamber 5, where it ignites and burns. The combustion products leave the combustion chamber 5 to be mixed with cooling air in the stack 7 before leaving the fluid combustion unit 1. The construction and function of fluid combustion units are well known in the art and will not be described in further detail herein.

The fluid burner system 3 comprises a fluid burner head 9, more particularly a gas burner head, which is shown in further detail in fig. 2-6. The fluid incinerator head 9 comprises a body 11, the body 11 in turn comprising a hollow elongate stainless steel tube 13 and a solid cap 15 of refractory concrete. The tube 13 and cap 15 are discrete separable elements having a circular periphery (as seen along the longitudinal central axis C of the fluid burner head 9).

The tube 13 has a wall 17 of uniform thickness along the longitudinal central axis C of the fluid burner head 9 and around the longitudinal central axis C of the fluid burner head 9. Referring to fig. 4, it comprises a lower end 19, a lower portion 21, an upper portion 23 and an upper end 25, which are arranged consecutively along a longitudinal centre axis C. The upper portion 23 of the tube 13 includes a plurality of circular holes 27 that extend through the wall 17 of the tube 13. The holes 27 are equidistantly arranged in rows 29. The rows 29 of holes 27 are parallel to each other and extend equidistantly around the longitudinal centre axis C of the fluid-burner head 9.

Referring to fig. 5, the cap 15 comprises an upper portion 31 and a bottom portion 33, the upper portion 31 and the bottom portion 33 being arranged concentrically with reference to the longitudinal central axis C of the fluid burner head 9. The boundary between the upper portion 31 and the bottom portion 33 of the cap 15 is shown in dashed lines. The upper portion 31 has the basic shape of a circular plate with a constant cross section along the longitudinal centre axis C. The bottom portion has the basic shape of a truncated cone with a circular cross-section decreasing along the longitudinal centre axis C in a direction away from the upper portion 31 of the cap 15. The maximum cross-section of the bottom portion 33 is smaller than the cross-section of the upper portion 31.

As is clear from the figures (and in particular from fig. 5), the cap 15 closes the upper end 25 of the tube 13. The bottom portion 33 of the cap 15 has a maximum circumference smaller than the inner circumference of the tube 13 and it is housed inside the tube 13. The upper portion 31 of the cap 15 has a periphery substantially equal to the outer periphery of the tube 13 and greater than the inner periphery of the tube 13. An upper portion 31 of the cap 15 is arranged outside the tube 13 and abuts an annular edge thereof defining the upper end 25 of the tube 13. Due to the above-specified relative dimensions of the tube 13 and the cap 15, an annular groove 35 is formed between the bottom portion 33 of the cap 15 and the tube 13.

Referring to fig. 5 and 6a-c, the fluid incinerator head 9 further comprises: an annular support 37 in the form of a flat circular ring of stainless steel; an annular first projection 39 in the form of a stainless steel circularly extending skirt; and an annular second projection 41 in the form of a very short tube of stainless steel with a circular cross section. The support 37, the first projection 39 and the second projection 41 are arranged concentrically with reference to the longitudinal centre axis C of the fluid burner head 9. The first protruding portion 39 protrudes upward and outward from the outer edge of the support 37, and the second protruding portion protrudes downward from the outer edge of the support 37. The support 37, the first projection 39 and the second projection 41 are integrally formed as an arrangement designed to cooperate with the body 11 of the fluid burner head 9. More particularly, the support 37 is positioned and sandwiched between the tube 13 and the cap 15, with the first 39 and second 41 projections protruding from the outer surface 43 of the body 11 (fig. 3). The first protrusion 39 has an annular longitudinal first edge 39a and a second edge 39b (fig. 6 a) extending along each other. The first protrusion 39 is engaged with the body 11 indirectly (more particularly via the support 37) at the first edge 39a and along the first edge 39a, while the second edge 39b is free. The second projection 41 has an annular longitudinal first edge 41a and a second edge 41b (fig. 6 b) extending along each other. The second protrusion 41 surrounds the body 11 and its inner side contacts the outer surface 43 of the body 11 between the first edge 41a and the second edge 41 b. The tube 13 and the cap 15 are connected by means of elements not shown in the figures. Thus, at the boundary 45 (fig. 5) between the tube 13 and the cap 15, i.e. above the uppermost row 29a of the rows 29 of holes 27 (fig. 3), the support 37 and the first 39 and second 41 projections extend around the longitudinal centre axis C of the fluid burner head 9. Further, with particular reference to fig. 5 and 6C, the support 37 is sandwiched between the tube 13 and the cap 15 such that the first projection 39 projects obliquely upward at an angle α=30 degrees with respect to the longitudinal central axis C of the fluid burner head 9, while the second projection 41 projects downward and from the outer surface 47 of the tube 13 so as to enclose the uppermost portion of the tube 13.

The fluid burner head 9 is arranged to deliver vaporized gas to be combusted into the combustion chamber 5 of the fluid combustion unit 1 (fig. 1). More particularly, referring to fig. 4, the vaporised gas is arranged to be fed into the interior 49 of the tube 13 of the fluid burner head 9 via the lower end 19 of the tube 13, then up through the lower portion 21 of the tube 13, and then into the upper portion 23 of the tube 13, and further through the holes 27 of the tube wall 17 to the exterior 51 of the tube 13, and thus into the combustion chamber 5 (fig. 1). Inside the combustion chamber 5, the boil-off gas ignites and burns in a flame, as previously discussed. The first projection 39 and the second projection 41 are arranged to force the vaporising gas (and hence the combustion flame) away from the body 11 of the fluid burner head so that its temperature is kept low enough to avoid melt damage to the tube 13 and rupture damage to the cap 15 (even when the vaporising gas pressure and the vaporising gas velocity through the aperture 27 are relatively low). The frusto-conical shape of the bottom portion 33 of the cap 15 is arranged to accelerate the velocity of the vaporised gas passing through the aperture 27 proximate the upper end 25 of the tube 13 to help reduce the temperature of the body 11 and thus minimise damage to the body 11. The first 39 and second 41 protrusions will protect and shield the body 11 of the fluid burner head 9 and will be subjected to a harsh environment. If the first 39 and second 41 projections are damaged and when the first 39 and second 41 projections are damaged, the arrangement consisting of the support 37 and the first 39 and second 41 projections can be replaced with a new one, and the tube 13 and cap 15 can be used further.

The above-described embodiments of the invention should be regarded as examples only. Those skilled in the art will recognize that the embodiments discussed may be varied in many ways without departing from the inventive concepts.

As an example, the fluid incinerator head need not include the second protrusion, but may include only the first protrusion.

As another example, the fluid incinerator head need not include a support for securing the first and possibly the second projections to the fluid incinerator head body. Alternatively, the first projection and possibly the second projection may be directly fixed to the body of the fluid-incinerator head.

As yet another example, the support need not be secured to the body of the fluid incinerator head by being sandwiched between the tube and the cap. In alternative embodiments of the invention, the support may be arranged on the outside of the tube and/or cap in a tight fit so as to be held in place by friction. Thus, the first protrusion and the second protrusion do not need to be arranged at the boundary between the tube and the cap.

The first and second protrusions need not be formed separately from the tube and cap, but may be formed integrally with the tube and/or cap. Such designs may undermine the possibility of replacing only the first and second protrusions and the support (if present) in those cases where they are damaged.

The angle α between the first protrusion and the longitudinal centre axis of the fluid burner head need not have the above values, but may be larger or smaller.

The tube and cap need not be formed separately and from different materials, but may instead be integrally formed and/or made from the same material.

It should be emphasized that the detailed description not related to the present invention has been omitted and the figures are merely schematic and not drawn to scale. It should also be noted that some of the figures are more simplified than others. Thus, some components may be shown in one figure and omitted from another figure. Finally, as used herein, the prefixes "first," "second," etc. are used merely to distinguish between different components and do not result in a requirement regarding relative positioning or orientation.

Claims

1. A fluid burner head (9) for a fluid combustion unit (1), the fluid burner head (9) comprising a body (11), the body (11) in turn comprising a hollow tube (13) for transporting fluid to be combusted into a combustion chamber (5) and a cap (15) at least partially closing an upper end (25) of the tube (13), the tube (13) further comprising a lower end (19) for receiving the fluid in the tube (13), a wall (17) of the tube (13) comprising a plurality of rows (29) of holes (27), the rows (29) extending around a longitudinal centre axis (C) of the fluid burner head (9), wherein the holes (27) allow the fluid to be combusted to flow from an interior (49) to an exterior (51) of the tube (13), the fluid burner head (9) being characterized in that it further comprises an annular first protrusion (39), the first protrusion (39) extending around the longitudinal centre axis (C) of the fluid burner head (9), and protrudes obliquely at an angle α with respect to the longitudinal centre axis (C) of the fluid burner head (9) from the outer surface (43) of the body (11) and away from the lower end (19) of the tube (13) above the uppermost row (29 a) of holes (27) of the tube (13), wherein 0< α <90 degrees, the uppermost row (29 a) of holes (27) is the row of holes (27) arranged closest to the cap (15).

2. The fluid incinerator head (9) according to claim 1, wherein the tube (13) and the cap (15) are formed separately.

3. A fluid incinerator head (9) according to any preceding claim, wherein the cap (15) and the tube (13) are made of different materials.

4. The fluid incinerator head (9) according to any of the preceding claims, wherein said first protrusion (39) protrudes from an outer surface (43) of said main body (11) at a boundary (45) between said tube (13) and said cap (15).

5. A fluid incinerator head (9) according to any of claims, wherein the tube (13) and the first projection (39) are formed separately.

6. A fluid incinerator head (9) according to any of the preceding claims, wherein the upper portion (23) of the tube (13) comprising the holes (27) has a substantially uniform cross section along the longitudinal central axis (C) of the fluid incinerator head (9).

7. The fluid burner head (9) according to any of the preceding claims, further comprising an annular support (37) extending around a longitudinal centre axis (C) of the fluid burner head (9), the support (37) being connected to the first protrusion (39) and engaging with a body (11) of the fluid burner head (9) to fix the first protrusion (39) to the body (11).

8. A fluid burner head (9) according to any one of claims 1-6, further comprising an annular second protrusion (41), said second protrusion (41) extending around a longitudinal central axis (C) of the fluid burner head (9) and protruding from an outer surface (43) of the body (11) between the holes (27) of the uppermost row (29 a) of tubes (13) and the first protrusion (39).

9. A fluid incinerator head (9) according to claim 8, wherein the second projection (41) projects from an outer surface (47) of the tube (13).

10. The fluid burner head (9) according to any one of claims 8-9, further comprising an annular support (37) extending around a longitudinal centre axis (C) of the fluid burner head (9), the support (37) being connected to the first and second protrusions (39, 41) and being engaged with a body (11) of the fluid burner head (9) to fix the first and second protrusions (39, 41) to the body (11).

11. A fluid incinerator head (9) according to any of claims 7 or 10, wherein the support (37) is sandwiched between the cap (15) and the tube (13).

12. A fluid incinerator head (9) according to any of the preceding claims, wherein the cap (15) comprises an upper portion (31) and a bottom portion (33), wherein the bottom portion (33) protrudes into the tube (13).

13. The fluid incinerator head (9) according to claim 12, wherein said bottom portion (33) comprises a portion tapering in a direction away from an upper portion (31) of said cap (15).

14. A fluid incinerator head (9) according to any of claims 12 to 13 wherein the outer periphery of the upper portion (31) of the cap (15) is greater than the inner periphery of the tube (13).

15. Use of a fluid burner head (9) according to any of claims 1-14 in a fluid combustion unit (1) for burning boil-off gas from a fuel tank on a ship.