KR20190016097A - A pin for a boiler tube arrangement and an assembly comprising such a pin - Google Patents

Abstract

(4, 4a, 4b, 4c, 4d) for a boiler tube arrangement comprising a plurality of boiler tubes (34, 36, 38, 40) extending along each other, and such boiler tube arrangements and such pins Is provided. The longitudinal center axis C of the fin is arranged to extend at right angles to the length of the boiler tube and the fins include an inner edge 8 and an outer edge 10. The pin is characterized in that the outer edge of the inner edge is similar to the outer edge of the outer edge. Each of the contours of the inner and outer edges defines a plurality of ridges 16,18,20,26,28,30 and a plurality of valleys 12,14,22,24 such that the ridges and valleys are arranged alternately (H, H ') and the lowest point (L, L') of the connected ridges and valleys, respectively. Each of the valleys defined by the inner edges is arranged to extend below 180 degrees about each longitudinal longitudinal axis A of the boiler tube to receive the boiler tube and thereby partially surround each of the boiler tubes accordingly .

Description

A pin for a boiler tube arrangement and an assembly comprising such a pin

The present invention relates to a fin for a boiler tube arrangement comprising a plurality of boiler tubes extending along each other, the pins being arranged to extend at right angles to the length of the boiler tube. The present invention also relates to an assembly comprising a boiler tube arrangement comprising two such fins and a first boiler tube.

Boilers are well known and are used in many different heat exchange applications, for example in the field of waste heat recovery applications. Known waste heat recovery boilers, which are used, for example, behind a diesel engine to recover heat from exhaust gas from diesel engines, include a closed vessel and a plurality of tubes extending along each other within the vessel. A medium, such as water, is fed through the tube and exhaust gas from the diesel engine is fed through the vessel and around the tube thereby transferring heat from the exhaust gas to the medium inside the tube. In order to increase the heat transfer efficiency of the boiler, the tubes may be provided with surface enlargement elements in the form of fins attached to the tubes. Typically, the fins are formed as rectangular plates provided with voids for receiving the tubes. Even when such pins are widely used and meet their required purpose, there is still room for improvement.

It is an object of the present invention to provide a fin for a boiler tube arrangement that is improved over prior art fins. The basic idea of the present invention is to provide a pin having a unique, preferred shape that enables all parts of the fin to contribute significantly to the increase in heat transfer efficiency and to produce fins with little waste or scrap. It is a further object of the present invention to provide an improved assembly comprising such a fin and a boiler tube arrangement. The pins and assemblies that accomplish the above objects are defined in the appended claims and discussed below.

There is provided a fin according to the present invention for a boiler tube arrangement comprising a plurality of boiler tubes extending along each other. The longitudinal center axis of the fin is arranged to extend perpendicularly to the length of the boiler tube, and the fin includes an inner edge and an outer edge. The fin is characterized in that the contour of the inner edge is similar or essentially identical to the contour of the outer edge, and each of the contours of the inner and outer edges define a plurality of ridges and a plurality of valleys. The ridges and valleys are alternately arranged and connected to each other at the transition, and the transition is intermediate between the highest and lowest points of the connected ridges and valleys, respectively. Each of the valleys defined by the inner edges extends by 180 degrees or less around each longitudinal axis of each of the boiler tubes or each of the boiler tubes to receive the boiler tubes and thereby enclose each of the boiler tubes only partially . In other words, each of the valleys is arranged to extend only on one side of the central extension plane which divides each of the boiler tubes longitudinally in half.

In the present description, the expressions "ridge" and "valley" are used to specify the shape of the pin with respect to the longitudinal axis of the pin extending between the ridges and valleys of the inner and outer edges when the pin has a particular orientation. Of course, if the pin is upside down, the valley is in fact Lizzie, while Lizzie is in fact the Valley. However, throughout this specification, what is defined as the valleys and ridges of the pin when having the particular orientation will be referred to as the valley and ridges, regardless of the orientation of the pin.

The number of boiler tubes in the boiler tube arrangement may be more than one. In addition, the number of valleys defined by each of the inner and outer edges may be more than one. Likewise, the number of ridges defined by each of the inner and outer edges may be more than one.

As mentioned above, the fin has an extension perpendicular to the length of the boiler tube. Of course, the fins can be arranged to extend obliquely with respect to the length of the boiler tube, i. E. Perpendicular to the length of the boiler tube and with an extension extending therefrom.

Because of similar or basically identical inner and outer pin edges, the ridge defined by the inner pin edge fits into and fills it in the valley defined by the outer pin edge while the valley defined by the outer pin edge is limited by the inner pin edge Into the ridge to fill it. In other words, two similar fins fit within one another when the inner edge of one of the pins faces the outer edge of the other of the pins. Accordingly, the plurality of pins according to the present invention can be manufactured in a very material efficient manner by cutting from a sheet, typically a metal sheet, with minimal waste. Similar or basically the same means that the inner and outer edges do not need to be 100% identical and are sufficiently similar to enable pin interconnection. Thus, for example, the inner pin edge with a small recess or the like is similar or essentially the same as the outer pin edge without such recess. However, the contour of the inner edge may also be the same as the contour of the outer edge.

The portion of the fin that is further away from the tube will contribute less heat transfer than the portion of the fin that is closer to the tube. Because of the pin according to the invention having a wavy shape instead of a rectangular conventional shape in which the tube receiving void is provided, the extension of the pin can be adjusted according to the distance from the tube so that all parts of the pin contribute significantly to heat transfer. As a result, the fin can be made lighter and smaller with less material consumption, and accordingly, it can still contribute significantly to heat transfer.

The valley, or more specifically the shape of the valley, may have a ridge, or more specifically, a non-uniform, i.e., different shape, than the ridge's contour. In other words, the valley may be accommodated in the ridge, but it will not fill it, and vice versa. As a result, two similar pins are not fitted into one another when the outer edge of one of the pins faces the outer edge of the other one of the pins, or when the inner edge of one of the pins faces the inner edge of the other of the pins. Instead, the distance between the two pins will change. This may be desirable in terms of heat transfer efficiency, as will be explained further below.

Below, the shape of the pin is discussed primarily for the inner pin edge. However, since the shapes of the inner and outer pin edges are similar or essentially the same, the following discussion is also applicable at least in part with respect to the outer pin edge.

The fin can be configured to be arranged between the first and second ridges of the ridges defined by the contour of the inner edge and the first valley of the valley having the bottom defined by the contour of the inner edge and having a respective top. Also, the second ridge may be arranged between the first and second valleys defined by the contour of the inner edge. Accordingly, the pin can be configured to be arranged between two ridges defined by the contour of the inner edge and the first of the valleys having the bottom defined by the contour of the inner edge. In addition, the second ridge of the ridge defined by the contour of the inner edge can be arranged between two of the valleys defined by the contour of the inner edge, and the second ridge has the top. Such an embodiment means that the number of valleys is at least two, such as the number of ridges, defined by the inner pin edges.

The outer shape of the first valley may be shorter than the outer shape of the second ridge. This is a simple way of achieving the above-mentioned non-uniformity between the valley and the ridge.

The pin may be configured such that the first valley has a symmetry axis extending perpendicularly to the longitudinal center axis of the pin. Additionally, the second ridge may also have a symmetrical axis extending perpendicularly to the longitudinal center axis of the pin. This can facilitate and provide optimized fit of each boiler tube in the first valley.

The top of the second ridge is planar and may be defined by the first straight portion of the inner edge. Also, the bottom of the first valley is planar and can be defined by the second straight portion of the inner edge. Accordingly, the pin can be configured such that the bottom of the first valley and the top of the second ridge are planar and defined by respective straight portions of the inner edge. These straight portions may or may not extend parallel to the longitudinal center axis of the pin. Thereby, if the boiler tube has a circular cross-section as in the prior art, an area without contact between the fin and the boiler tube (s) can be assured. This may be desirable in connection with the cleaning of fins and boiler tubes.

The first valley may also be circular. This may be desirable in connection with the coupling between the fins and each of the boiler tubes, especially in the case of boiler tubes with circular outboards, since an increase in the pin-boiler tube contact surface can thereby be made possible.

The first valley may be defined by at least a partial waffle, sawtooth or ribbed third portion of the inner edge. The second portion above the inner edge may form part of the third portion, wherein the third portion will comprise a straight or planar, and also a waffle, portion. The waffle-shaped portion of the inner edge may be desirable in terms of heat transfer efficiency, as will be discussed further below.

The flanks connecting the bottom of the first valley and the top of the second ridge may be defined by at least a partial linear portion of the inner edge. This flank forms part of both the first valley and the second ridge. Thereby, if the boiler tube has a circular cross-section as in the prior art, an area without contact between the fin and the boiler tube (s) can be assured. This may be desirable in connection with the cleaning of fins and boiler tubes.

The pin is arranged such that the distance between two adjacent transitions of the transition defining the second ridge, i. E. The distance between the transitions that the second ridge extends, is between two adjacent transitions of the transition defining the first valley, It is larger than the distance between the transitions that the valley extends. This is a simple way of achieving the above-mentioned non-uniformity between the valley and the ridge.

The assembly according to the invention comprises a boiler tube arrangement comprising a first boiler tube and first and second pins of the type described above. The first and second fins extend perpendicularly to the longitudinal center axis of the first boiler tube on opposite sides of the first boiler tube. The inner edges of each of the first and second fins are partially surrounded only by the first boiler tube. The first boiler tube is received in each of the valleys defined by the inner edges of the first and second pins. Accordingly, each of the valleys defined by the inner edges of the first and second fins is arranged on an opposite side of the first boiler tube, each of the valleys being arranged at a distance of 180 degrees around the longitudinal central axis of the first boiler tube Deg. To accommodate the first boiler tube and thus surround the first boiler tube at least partially together.

Of course, the first fin and / or the second fin can extend obliquely with respect to the longitudinal central axis of the first boiler tube, i.e. they can have an extension perpendicular to the length of the first boiler tube and also along its extension.

Accordingly, the inner edges of the first and second fins face each other and at least partially surround the first boiler tube together. The outer edge of one or both of the first and second fins may be arranged to face the outer edge of another adjacent pin, as in the embodiment described below.

The assembly may be configured so that the boiler tube arrangement further comprises a third boiler tube extending along the first boiler tube and third and fourth pins of the type described above. The third and fourth fins may extend at right angles to the longitudinal center axis of the third boiler tube on opposite sides of the third boiler tube. The inner edges of each of the third and fourth fins can partially surround only the third boiler tube in confronting relation to the third boiler tube and the third boiler tube is defined by the inner edges of the third and fourth pins May be accommodated within each of the valleys. Accordingly, each of the valleys defined by the inner edges of the third and fourth fins is arranged on the opposite side of the third boiler tube, and each of the valleys is arranged 180 Deg., To accommodate the third boiler tube and thus surround the third boiler tube at least partially together. Also, one of the valleys defined by the outer edge of the third pin may be received within one of the ridges defined by the outer edge of the second pin, and one of the valleys defined by the outer edge of the second pin, And can be received within one of the ridges defined by the outer edges of the three pins.

Accordingly, the wavy configuration of the fins allows for a staggered arrangement of boiler tubes and a small assembly, since adjacent pairs of fins can be received within each other. Conventional rectangular pins do not enable such a small assembly.

The assembly may be configured such that the second pin partially surrounding the first boiler tube and the third pin partially surrounding the third boiler tube are separated from each other. Thereby, medium flow between the second and third pins, which leads to an increase in flow turbulence and thus an improvement in heat transfer, is made possible. Such separation can also facilitate the cleaning of the fins, e.g. the removal of soot deposits from the fins resulting from the exhaust gas.

Depending on the design of the second and third pins, the distance between them may vary or be constant along their length. According to an embodiment of the present invention, the distance between the outer edge of the second pin and the outer edge of the third pin is varied along the outer edge of the second and third pins. Such a distance variation can be achieved with second and third pins as described above, i.e., second and third pins having non-uniform valleys and ridges with each other. The change in distance between the second and third fins can lead to an increase in flow turbulence and hence an improvement in heat transfer.

The assembly can be configured such that the first and second fins surrounding the first boiler tube are separated from each other by a predetermined distance. Thereby, the first boiler tube is not completely surrounded by the first and second fins. This allows media flow between the first and second pins, resulting in an increase in flow turbulence and hence an improvement in heat transfer. This can also facilitate the cleaning of the fin and the first boiler tube.

According to one embodiment of the assembly, an outer contour of the first boiler tube at the first and second fins and an outer contour of the first boiler tube at the inner edge of the first and second pins to receive the first boiler tube between the first and second pins The space delimited by them is non-uniform, i. E., Has a different shape. Thereby, an area free of contact between the first and second pins and the first boiler tube can be assured, thereby facilitating the cleaning. For example, such non-uniformity can be obtained by a first boiler tube having a circular external contour or cross-section, as mentioned above, and the space containing the first boiler tube is at least partially .

The first and second fins may be engaged with the first boiler tube at a point of disassociation from each other. Thereby, an area free of contact between the first and second pins and the first boiler tube can be assured, thereby facilitating the cleaning.

Of course, the advantages associated with the different embodiments of the pins discussed above are also desirable for an assembly comprising pins.

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

The present invention will now be described in more detail with reference to the accompanying schematic drawings, in which: Fig.
1 is a plan view of a metal sheet for producing a fin.
2 is a plan view of the pin.
3 is a plan view of the assembly.
4 is a top view of a metal sheet for making pins of an alternate design.
Figure 5 is a plan view of an alternative design pin.
Figure 6 is a top view of an assembly of an alternative design.

In Figure 1 a metal sheet 2 is shown and four identical pins 4 from the metal sheet 2 can be obtained by cutting the sheet along the line 6. [ The pins obtained are wave-shaped and, more specifically, they have a wave-shaped inner edge 8 and a wave-shaped outer edge 10, and such inner and outer edges have the same outer shape. One of the pins is shown separately in Fig. 2, and from Fig. 2 the inner edge 8 of each pin 4 is shown as the first valley 12, the second valley 14, the first ridge 16, It is clear that the two ridges 18 and the third ridges 20 are limited. The first valley 12 is arranged between the first and second ridges 16 and 18 and the second valley 14 is arranged between the second and third ridges 18 and 20, 18 are arranged between the first and second valleys 12, 14. The transition P between the ridge and adjacent valleys is midway between the highest point (H) of the ridge and the lowest point (L) of the valley. The first and second valleys 12 and 14 are the same and the first and third ridges 16 and 20 are the same as the respective portions of the second ridge 18.

Likewise, the outer edge 10 of each pin 4 has a first valley 22, a second valley 24, a first ridge 26, a second ridge 28 and a third ridge 30 It limits. The first valley 22 is arranged between the first and second ridges 26 and 28 and the second valley 24 is arranged between the second and third ridges 28 and 30, 28 are arranged between the first and second valleys 22, 24. The transition (P ') between the ridge and the adjacent valley is midway between the highest point (H') of the ridge and the lowest point (L ') of the valley. The first and second valleys 22 and 24 are identical and the first and third ridges 26 and 30 are identical to the respective portions of the second ridge 28. [ As a result, since the valleys and ridges of the inner and outer pin edges 8 and 10 have the same depth and height, respectively, the transition P with respect to the inner edge 8 is arranged along the virtual straight line I , Transitions P 'relative to the outer edge 10 are arranged along a virtual straight line I'. The longitudinal center axis C of the pin is arranged midway between the imaginary straight lines I and I '.

Each of the first valley 12,22 and the second valley 14,24 has a symmetry axis S extending perpendicularly to the longitudinal center axis C of the pin 4. Likewise, each of the second ridges 18, 28 has a symmetry axis R extending perpendicularly to the longitudinal center axis C of the pin 4. Each of the first and second valleys 12 and 22 and the second valley 14 and 24 has a planar bottom portion B and B 'extending in parallel to the longitudinal central axis C of the pin. Likewise, each of the first ridges 16, 26, the second ridges 18, 28 and the third ridges 20, 30 are arranged in parallel with the longitudinal center axis C of the pins, (T, T '). Furthermore, each of the flanks (F, F ') connecting the top and bottom of the ridges and valleys of the inner and outer pin edges includes a straight portion.

As is apparent from the figure, the shape of the valleys 12, 14, 22, 24 is such that the ridges are less "sharp" or less "sharper" than valleys, and between two adjacent transitions of the transitions defining one of the ridges 18, 20, 26, 28, 30 in that the distance of the ridges 16, 18, 20, 26, 28, 30 is greater than the distance between the two adjacent transitions in the transition defining one of the valleys, It is different from the shape. Thus, by way of example, the area A1 defined by the imaginary straight line I 'and the contour of the first valley 22 is defined by the imaginary straight line I' and the area defined by the contour of the second ridge 28 (A2).

Referring to Figure 1, each of the lines 6 defines an inner edge 8 of one pin 4 and an outer edge 10 of adjacent pins 4. Since the inner and outer edges 8 and 10 have the same outer shape, the pin 4 is completely fitted into each other when the inner edge 8 of one pin faces the outer edge 10 of the adjacent pin , The valleys (22, 24) defined by the outer edges of the adjacent fins are received in the valleys (12, 14) defined by the inner edges of the one pin, respectively, and the inner edges of the one pin The ridges 16, 18 and 20 defined by the adjacent pins are received in the defined ridges 26, 28 and 30, respectively, by the outer edges of the adjacent pins. As a result, the pin 4 can be cut from the sheet 2 with a minimum waste material.

In Figure 3, an assembly 32 comprising a plurality of parallel boiler tube boiler tube arrangements and the same number of pins 4 of the type described above is shown. Assembly 32 is contained within a waste heat recovery boiler of the type described above (not shown in its entirety), whereby water is fed into the boiler tube and exhaust gas is sent out of the boiler tube to transfer heat from the exhaust gas to water . The boiler tubes are arranged in pairs between two opposing pins of the fins. Thereby, first and second boiler tubes 34, 36 are arranged between the first and second fins 4a, 4b, which are separated from each other in x dimension by a certain distance, Third and fourth boiler tubes 38, 40, which are separate from one another in the plane, are arranged between the third and fourth pins 4c, 4d.

The first and second fins 4a and 4b are thus arranged on opposite sides of the first and second boiler tubes 34 and 36 in alignment with one another in the dimensions z and y, The longitudinal center axis C (Fig. 2) extends parallel to one another and at right angles to the longitudinal center axis A of the first and second boiler tubes. In addition, the first and second fins 4a, 4b are separated from each other by a predetermined distance in the y dimension and are arranged such that their inner edges 8 face each other. The first boiler tube 34 is received in the space defined by the first valley 12 of the first pin 4a and the second valley 14 of the second pin 4b while the second boiler tube 36 are accommodated in the space defined by the second valley 14 of the first pin 4a and the first valley 12 of the second pin 4b. Accordingly, the first and second boiler tubes 34, 36 are partially surrounded by the first and second fins 4a, 4b. After this arrangement, the first and second boiler tubes are distributed around the first and second boiler tubes, here the first and second pins 4a, 4b ). ≪ / RTI >

Likewise, the third and fourth fins 4c, 4d are arranged on opposite sides of the third and fourth boiler tubes 38, 40, aligned with one another in dimensions z and y, The longitudinal center axis C is parallel to each other and extends at right angles to the longitudinal center axis A of the third and fourth boiler tubes. Also, the third and fourth pins 4c, 4d are separated from each other by a predetermined distance in the y dimension and are arranged such that their inner edges 8 face each other. The third boiler tube 38 is accommodated in the space defined by the first valley 12 of the third pin 4c and the second valley 14 of the fourth pin 4d while the fourth boiler tube 40 are accommodated in the space defined by the first valley 12 of the second valley 14 and the fourth pin 4d of the third pin 4c. As such, the third and fourth boiler tubes 38, 40 are partially surrounded by the third and fourth pins 4c, 4d. After this arrangement, the third and fourth boiler tubes are distributed around the third and fourth boiler tubes, here 6 per boiler tube, at the welding point 42, third and fourth pins 4c, 4d ). ≪ / RTI >

3, all of the first, second, third and fourth boiler tubes 34, 36, 38, 40 have the same circular shape or contour, i.e. the same circular cross-section. Also, all of the space formed by the first, second, third and fourth fins 4a, 4b, 4c, 4d for receiving the boiler tube are all formed in the same corner shape Respectively. Because of this difference in geometry, the boiler tube will not contact each pin around its entire outer surface. Instead, the boiler tubes will be separated from the respective fins in the areas 44, 46 between the welding points, where each of the areas 44 is formed between one of the fins and one of the boiler tubes, 46 are formed between one of the pin pairs and one of the boiler tubes. This fin-boiler tube separation results in an increase in the flow turbulence of the exhaust gas around the boiler tubes and fins, thereby increasing the heat transfer from the exhaust gases to the water fed through the boiler tubes.

The first, second, third and fourth pins 4a, 4b, 4c, 4d are arranged such that their longitudinal axis C extends parallel to one another. The outer edge 10 of the second pin 4b is aligned with the outer edge 10 of the third pin 4c and the outer edge 10 of the second pin 4b is aligned with the outer edge 10 of the third pin 4c, do. The third and fourth boiler tubes 38 and 40 are displaced from the first and second boiler tubes 34 and 36 in x dimension so that the fourth boiler tube 40 is connected to the first boiler tube 34, And the first boiler tube 34 is arranged in the middle between the third and fourth boiler tubes 38, As a result, the pin pairs 4a + 4b and 4c + 4d have a staggered arrangement. Here, the staggered arrangement means that the pairs of pins are not aligned with respect to each other in the y dimension, but instead are displaced. More specifically, the first valley 22 defined by the outer edge of the third pin 4c is received in a third ridge 30 defined by the outer edge of the second pin 4b, The first valley 24 defined by the outer edge of the third pin 4b is received in the second ridge 28 defined by the outer edge of the third pin 4c The second valley 24 defined by the second pin 4b is received in a second ridge 28 defined by the outer edge of the second pin 4b and is defined by the outer edge of the second pin 4b, 22 are received in a third ridge 30 defined by the outer edges of the third pin 4c.

Accordingly, the valley of the second fin is received within the ridge of the third pin while the valley of the third fin is received within the ridge of the second fin. The second and third pins 4b and 4c are arranged separately from each other. Since the ridges and valleys have different shapes, the distance between the second and third pins, and more specifically their outer edges, is varied along the longitudinal center axis C of the second and third pins. This change in distance results in an increase in the turbulence of exhaust gas flow around the boiler tubes and fins, thereby increasing the heat transfer from the exhaust gases to the water being fed through the boiler tubes.

The rest of the assembly is constructed in a manner corresponding to that described above and accordingly the description is unnecessary.

A pin according to an alternative embodiment of the present invention, and an assembly comprising a plurality of such pins, will now be described with reference to Figures 4-6. Most of the description given above for pins and assemblies according to the first embodiment of the present invention is also valid for the pins and assemblies according to the alternative embodiment and in order to avoid excessive repetition, Lt; / RTI > In addition, the same reference numerals are used for similar / corresponding features of the two embodiments.

For example, as is apparent from Fig. 5, the first valley 12, 22 and the second valley 14, 24 of the pin 4 according to an alternative embodiment are circular. Each of which is defined by a waffle-shaped portion 48 of the inner and outer edges 8, 10 of the pin 4, such waffle-shaped portions defining spikes or protrusions or teeth. Each of the first ridges 16 and 26, the second ridges 18 and 28 and the third ridges 20 and 30 has a planar top T extending parallel to the longitudinal center axis C of the pin, T '). The first ridges 16 and 26, the second ridges 18 and 28 and the third ridges 20 and 30 are connected to the waffle-shaped portion 48 at the transition to the adjacent valley, (f, f '). The waffle-like flank portion defines a spike or protrusion or tooth.

Figure 6 shows an assembly 32 comprising a plurality of parallel boiler tube boiler tube arrangements and the same number of fins 4 according to an alternative embodiment of the present invention. The fin (4) is welded to the boiler tube along its inner edge (8). With regard to welding, spikes or protrusions or teeth along the inner edge 8 of the fins 4 are melted and thus along the entire valley along the inner edge 8 of the pin and along the flank portion f of the ridge A continuous welded portion 50 is formed. These successive welds enable the increase of the contact surface and thus the heat transfer between the fin and the boiler tube and also the reliable fastening of the pin to the boiler tube.

6, and as noted above, the valleys 12, 14, 22, 24 of the pin 4 are circular while the ridges 16, 18, 20, 26, 28, . Accordingly, the distance between two adjacent fins partially enclosing different boiler tubes, such as the second and third pins 4b, 4c, will change significantly more than in the assembly shown in Fig. This will result in a much larger exhaust flow turbulence around the boiler tubes and pins, and thus a much larger heat transfer from the exhaust gases to the water being fed through the boiler tube.

Also, the spikes or projections along the outer edges of the fins will further increase the heat transfer due to the exhaust gas flow turbulence.

The above-described embodiments of the present invention should be considered as examples only. Those skilled in the art will recognize that the embodiments discussed may be varied and combined in various ways without departing from the inventive concept.

For example, the fins and assemblies according to the present invention may be used to heat, vaporize, or overheat other media than water by other types of boilers other than waste heat recovery boilers, and by other heat sources other than exhaust gases. For example, the pin and assembly according to the present invention may be used in connection with a combustion unit such as a gas turbine or burner.

The distance between the pins 4b and 4c in Fig. 3 may be in the range of 1-20 mm, but other distances are of course possible. The distance may in particular depend on the dimensions of the fin and the boiler tube.

In the embodiment described above of the assembly of the present invention, the boiler tube is attached to the fin by welding. Of course, other attachment methods, such as brazing or bonding, are possible. Also, in the case of point-welding, the number of welding points between the pins and the boiler tube need not be six per boiler tube and may be less or more than six. Also alternatively, each pair of pins may be attached to each other, and the boiler tube may be secured to the pin only by friction.

Each of the pins described above is provided with two valleys and three ridges along each of the inner and other edges. Naturally, the number of ridges and valleys may be less or greater than three and two, respectively. By way of example, the inner and outer edges of each pin may define only two ridges and one valley arranged between the ridges. A pair of such pins may be arranged to surround only one boiler tube.

All pins of the assembly need not look the same. It is not necessary to look the same when the pins are the same pair. In addition, the number of cooperating fins surrounding one or more boiler tubes may be more than two. By way of example, the fins constructed in accordance with the drawings, i.e. arranged to partially surround two boiler tubes, can be arranged to cooperate with two fins arranged to partially surround each of the two boiler tubes.

The valleys defined by the inner pin edges need not be the same, such as the valleys defined by the outer pin edges. Also, the inner and outer edges of the pin need not include straight portions, and may be generally curved. Further, the boiler tube may have another cross-section than that shown in the drawings.

In the embodiment described above, the ridges are less "sharp" than the valleys and the ridges are longer than the valleys. Naturally, the fins can be designed in an alternative manner, for example, to be less sharp than the valley margin and the valley contour to be longer than the contour of the ridge.

The pins and boiler tubes may be made of any suitable material, such as carbon steel, stainless steel or aluminum. Also, the fins need not be solid and may include holes that further increase flow turbulence.

The pair of pins need not be aligned in y and z dimensions. By way of example, the pair of pins may be displaced relative to each other and not aligned in y dimension and / or z dimension. There is a likelihood of equal displacement for the z dimension between the pairs of pins.

In the embodiment described above, each of the boiler tubes is surrounded by a first valley defined by the inner corners of one fin and a second valley defined by the inner corners of another fin. Of course, depending on the manner in which the two pins are oriented, each of the boiler tubes may instead be surrounded by a first valley defined by the inner edges of the two pins, or by a second valley defined by the inner edges of the two pins .

It should be emphasized that the description of details not related to the present invention is omitted, and that the drawings are not drawn merely by schematic and constant scale. It should also be noted that some of the figures are simplified than others. Accordingly, some elements are shown in one drawing, but may be omitted in another drawing. Finally, as used herein, if one component is referred to as being connected to another component, the connection may be direct or indirect.

Claims (15)

(4, 4a, 4b, 4c, 4d) for a boiler tube arrangement comprising a plurality of boiler tubes (34, 36, 38, 40) (4, 4a, 4b, 4c, 4d), in which the fins are arranged to extend at right angles to the length of the boiler tube and the fins comprise an inner edge (8) and an outer edge (10) Each of the outward shapes of the inner and outer edges defining a plurality of ridges 16,18,20,26,28,30 and a plurality of valleys 12,14,22,24, Such ridges and valleys are alternately arranged and connected to one another at the transition points P and P 'and the transitions are respectively connected between the highest points H and H' of the connected ridges and valleys and the lowest points L and L ' And each of the valleys defined by the inner edges extends 180 degrees or less around each longitudinal center axis A of the boiler tube, Receiving, and thereby arranged to partially surround, only each of the boiler tubes, characterized in that the pin (4, 4a, 4b, 4c, 4d). 2. The method according to claim 1, characterized in that the geometry of the valleys (12,14,22,24) is such that the contours of the ridges (16,18,20,26,28,30) and the uneven fins (4,4a, 4b, 4c, 4d ). 3. A device according to claim 1 or 2, characterized in that the first valley (12), defined by the contour of the inner edge (8) and having a bottom (B), is defined by the contour of the inner edge and has a respective top (4, 4a, 4b, 4c, 4d) arranged between the first and second ridges (16, 18). 4. The pin according to claim 3, wherein the outer shape of the first valley (12) is shorter than the contour of the second ridge (18). 5. A device according to claim 3 or 4, characterized in that the upper portion (T) of the second ridge (18) is flat and defined by a first straight portion of the inner edge (8) ). Method according to any one of claims 3 to 5, characterized in that the bottom part (B) of the first valley (12) is flat and is defined by a second straight part of the inner edge (8) , 4c, 4d). 7. A method according to any one of claims 3 to 6, wherein the first valley (12) is circular, the pins (4, 4a, 4b, 4c, 4d). 8. A device according to any one of claims 3 to 7, wherein the first valley (12) is defined by at least a partial waffle-shaped third portion (48) of the inner edge (8) , 4c, 4d). 9. A device according to any one of claims 3 to 8, wherein a flange (F) connecting the bottom (B) of the first valley (12) and the top (T) of the second ridge (18) The pins (4, 4a, 4b, 4c, 4d) being defined by at least partly linear portions of the pins (4, 4a, 4b, 4c, 4d). 10. A method according to any one of claims 3 to 9, wherein the distance between the two adjacent transitions of the transitions (P, P ') defining the second ridge (18) (4, 4a, 4b, 4c, 4d) greater than the distance between two adjacent transitions. An assembly (32) comprising a boiler tube arrangement comprising a first boiler tube (34) and first and second fins (4a, 4b) according to one of claims 1 to 10, And the second fin extend at right angles to the longitudinal center axis (A) of the first boiler tube on the opposite side of the first boiler tube and the inner edge (8) of each of the first and second fins And the first boiler tube is received within each of the valleys (12, 14) defined by the inner edges of the first and second pins. The boiler tube arrangement of claim 11, wherein the boiler tube arrangement comprises a third boiler tube (38) extending along the first boiler tube (34) and a third boiler tube (38) extending from the third and fourth pins 4c, 4d), the third and fourth fins extending perpendicularly to the longitudinal center axis (A) of the third boiler tube on the opposite side of the third boiler tube, and the third and fourth fins Each inner edge 8 is partially surrounded only by the third boiler tube and the third boiler tube is received in each of the valleys 12, 14 defined by the inner edges of the third and fourth pins One of the valleys 22 and 24 defined by the outer edge 10 of the third pin 4c has ridges 26,28 and 30 defined by the outer edge 10 of the second pin 4b. One of the valleys 22, 24 defined by the outer edge of the second pin is received within one of the ridges 26, 28, 30). ≪ / RTI > 13. The assembly of claim 12, wherein the distance between the outer edge (10) of the second pin (4b) and the outer edge (10) of the third pin (4c) is varied along the outer edge of the second and third pins 32). 14. A boiler according to any one of claims 11 to 13, characterized in that the outer contour of the first boiler tube (34) in the first and second fins (4a, 4b) and the outer contour of the first boiler tube The space for receiving the tube is non-uniform, the assembly (32). 15. A device according to any one of claims 11 to 14, wherein the first and second fins (4a, 4b) are coupled to a first boiler tube (34) at a coupling point (42) ).

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