Technical field of the solution

The presented solution especially relates to a support element for supporting one or more horizontal heat exchanger tubes. The support element is configured to be supported by and mounted on a vertical support tube. A system including the support element and the vertical support tube is applied in supporting heat exchanger tubes of a heat exchanger in a flue gas passage of a boiler.

Background of the solution

A steam generator or a boiler provided for combustion of fuel extracts heat energy from hot flue gases by means of heat exchanger placed in a flue gas passage along which the flue gases flow. The heat exchanger may include horizontal heat exchanger tubes that are adapted to pass heat from the hot flue gases to a fluid, a gas, or steam flowing inside the heat exchanger tubes.

A conventional method of supporting the horizontal heat exchanger tubes is to provide a vertical support tube, i.e. a stringer tube, extending past and between the horizontal heat exchanger tubes. The vertical support tube has a plurality of supporting arms fixed by welding to it and the horizontal heat exchanger tubes are supported on the supporting arms preventing the horizontal heat exchanger tubes from bending out of line. Typically, the vertical support tube is cooled by a liquid or gas, e.g. steam.

The multitude of welds on the vertical support tube placed in the hot and corrosive environment inside the flue gas passage may be problematic and when a fault appears in the support tube the repair work is difficult in such a case that the vertical support tube must be replaced.

When a group of the horizontal heat exchanger tubes must be replaced on account of a fault in one or several of the horizontal heat exchanger tubes, the repair work is especially difficult and time-consuming. This is because the vertical support tube and the supporting arms fixed to it hinder movements of the group of the horizontal heat exchanger tubes and/or collide with it when removing the horizontal heat exchanger tubes from the flue gas passage or installing a new group of horizontal heat exchanger tubes into the flue gas passage.

It would be desirable to provide a solution providing improved reliability and/or easier repair work with less time-consuming stages.

Brief summary of the solution

The support element according to the solution is presented in claim 1 .

A system for supporting horizontal heat exchanger tubes, the system including the support element, is presented in claim 12.

The use of the above-mentioned system in a flue gas passage of a boiler, the flue gas passage including a heat exchanger, is presented in claim 20.

A flue gas passage of a boiler, the flue gas passage including a heat exchanger and the above-mentioned system, is presented in claim 26.

A method in the above-mentioned flue gas passage of a boiler, the flue gas passage including a heat exchanger and the above-mentioned system, is presented in claim 28.

Other dependent claims present further details of the examples of the solution.

The support element according to the solution is for supporting at least one horizontal heat exchanger tube. The support element is configured to be mounted on a vertical support tube.

The support element comprises a main body including a hollow interior extending in a vertical direction through the main body and being configured to surround the vertical support tube passing through the hollow interior, and at least one supporting arm. Each supporting arm extends outwardly from and substantially perpendicular to the main body. Each supporting arm is configured to support at least one of the heat exchanger tubes in such a way that in a vertical direction a downward movement of the heat exchanger tube is prevented.

Preferably, each support element includes a plurality of such supporting arms, e.g. six to thirty-six pieces, for supporting a plurality of horizontal heat exchanger tubes.

The system according to the solution comprises a vertical support tube and one or more of the above-mentioned support elements. Each support element is mounted on the vertical support tube.

According to an example, for example to enable the mounting of and facilitate installation of the support element and the horizontal heat exchanger tubes, or for use during the installation, the support element is configured to rotate around the vertical support tube. The shape of the hollow interior is configured to allow the support element to rotate around a vertical direction about the vertical support tube.

According to an example, for example to enable the mounting of and facilitate installation of the support element, or for use during the installation, the support element is adapted to slide along the vertical support tube. The shape of the hollow interior is configured to allow the support element to slide along the vertical support tube.

According to an example, for example to enable installation of the support element, the vertical support tube is cooled by means of a liquid or gas (e.g. steam) flowing inside the vertical support tube.

The above-mentioned system is applied and used in the flue gas passage of a boiler for supporting at least one heat exchanger. The heat exchanger includes a group or an element including two or more of the horizontal heat exchanger tubes.

The advantages of the solution especially relate to the method in the flue gas passage of a boiler for removing or replacing the abovementioned group, element, or heat exchanger. The supporting arms are turned away from the horizontal heat exchanger tubes to avoid collisions. The method applies rotational, upward, lateral, and horizontal movements.

The presented solution is particularly advantageous and solves the above- mentioned problems.

For example, the presently disclosed support element removes the need for a multitude of welds on the vertical support tube that is load bearing. The support element can be replaced with a new one without replacing the vertical support tube. The use of vertical support tubes enables a longer heat exchanger and a wider flue gas passage.

The support element can be, for the most part, designed, manufactured, or installed in place separately from the vertical support tube. A plurality of short support elements that may be of uniform structure can be combined to form longer support elements for varying needs.

The presented solution facilitates the replacement of a heat exchanger, or a group of the horizontal heat exchanger tubes in the heat exchanger, for example an element of the heat exchanger. Especially in heat exchangers with a relatively small spacing between adjacent horizontal heat exchanger tubes, when in place in the passage for hot flue gases, removing and/or installing e.g. the element may be problematic, time-consuming, or impossible because the horizontal heat exchanger tubes, or curved tube sections of the horizontal heat exchanger tubes, collide with the adjacent horizontal heat exchanger tubes or the conventional supporting arms fixed to the vertical support tube.

The advantage of the presented solution is that that the support element with its supporting arms can be rotated about the vertical support tube in such a way that the supporting arms turn away from the horizontal heat exchanger tubes and may be placed in parallel to them. Now, for example in a vertically extending flue gas passage, the lifting and/or lowering of the heat exchanger or the group of the horizontal heat exchanger tubes, or the moving of the group of the horizontal heat exchanger tubes horizontally in a direction parallel to the horizontal heat exchanger tubes, is possible without colliding with the adjacent horizontal heat exchanger tubes, or the supporting arms of the support element. These and other non-limiting features, characteristics and advantages of the presented solution are more particularly disclosed below.

Brief description of the drawings

The following is a brief description of the drawings, which are presented for the purposes of illustrating the exemplary embodiments disclosed herein and not for the purposes of limiting the same.

Fig. 1 shows in a side view an example of a boiler in which the presented solution can be applied.

Fig. 2 shows in a side view an example of a flue gas passage in the flue gas channel of the boiler of Fig. 1 , together with a heat exchanger installed in the flue gas passage.

Fig. 3 shows a side view of an example of the support element according to presented solution and installed on a vertical support tube.

Fig. 4 shows the example of Fig. 3 as seen from above, the support element being in a support position and in a rotated position.

Fig. 5 shows a side view of another example of the support element according to presented solution and installed on a vertical support tube.

Fig. 6 shows the example of Fig. 5 as seen from above, the support element being in a support position and in a rotated position.

Fig. 7 shows a side view of the support element of Fig. 3.

Fig. 8 shows the support element of Fig. 7 as seen from above.

Fig. 9 shows a side view of the support element of Fig. 5.

Fig. 10 shows the support element of Fig. 9 as seen from above. Fig. 1 1 shows a top view of an example of the clamping element as applied in the presented solution.

Fig. 12 shows two side views of the clamping element of Fig. 12.

Detailed description of the solution

In the description, reference is made to the figures with the following reference numbers and denotations:

10 Boiler

12 Furnace

14 Cyclone

16 Flue gas channel

18 Support frame

20 Heat exchanger

22 Column

24 Supporting beam

26 Hanger

28 Horizontal heat exchanger tube

30 Support tube

32 Back wall

34 Front wall

36 Curved tube section

38 Header reservoir

40 Header reservoir

42 Support element

44 Main body

46 Supporting arm

48 Bracket

50 Clamping element

52 Opening

54 Notch

56 Cover part

58 Skirt part

60 Flue gas passage A more complete understanding of the features disclosed herein can be obtained by reference to the accompanying drawings. These figures are merely schematic representations and are not intended to indicate relative size and dimensions of the devices or components thereof or to define or limit the scope of the embodiments. The specific terms used in the following description are intended to refer only to the embodiments selected for the drawings and are not intended to define or limit the scope of the disclosure. In the drawings and the description below, like numeric designations refer to devices or components of like function.

In the following, the terms “horizontal” and “vertical” refer to the intended operating positions of the device or component in question when installed in place for implementing the functions of the described solution. The terms “horizontal” and “vertical” are used to indicate direction relative to an absolute reference, i.e. ground level. In the figures, the vertical direction is denoted by an arrow Z and the two orthogonal, horizontal directions are denoted by arrows X and Y. The horizonal directions are orthogonal in relation to the vertical direction.

Also, the terms “upper”, “lower”, “on top”, “below”, “upward”, and “downward” relate to the above-mentioned, intended operating positions. The terms “parallel” and “perpendicular” should not be construed to require structures to be absolutely parallel or absolutely perpendicular to each other. The term “opposite” should not be construed to require opposite directions to be absolutely parallel to each other.

Referring to Fig. 1 , one embodiment of a steam generator or a boiler 10 in which the present solution may be applied is shown. The boiler may be a part of a power plant, a steam boiler plant, or a hot water boiler plant, adapted for the production of electric energy, steam, and/or heating energy.

The boiler 10 includes a furnace 12 for the combustion of fuels and a flue gas channel 16 for conveying flue gases, i.e. combustion product gases, coming from the furnace 12.

The boiler 10 may comprise further devices that are relevant for the design in question but are not shown in the figures. The boiler 10 may additionally comprise a cyclone separator 14 connected to the furnace 12 for separating solid particles from the flue gases coming from the furnace 12 and for guiding the flue gases to the flue gas channel 16. The boiler 10 may further comprise a support frame 18 for supporting the furnace 12 and the flue gas channel 16 to the ground. The support frame 18 may include columns 22, supporting beams 24 and/or hangers 26 for supporting the furnace 12 and/or the flue gas channel 16 to the support frame 18.

The boiler 10 may be a boiler of CFB (circulating fluidized bed), BFB (bubbling fluidized bed), or grate boiler design. The fuel may be a gas, solid fuel or solid waste from various sources, e.g. municipal waste.

The flue gas channel 16 shown in Fig. 1 includes one vertical flue gas passage 60 in which flue gases flow downward. According to other examples, the flue gas channel 16 may include at least one vertical flue gas passage 60, or two or more consecutive vertical flue gas passages 60 in which flue gases flow downward or upward. According to another example, the flue gas channel 16 may include a horizontal flue gas passage 60 in which flue gases flow horizontally. The vertical flue gas passage 60 may be followed by the horizontal flue gas passage 60. The flue gas channel 16 and the flue gas passage(s) 60 may be at least in part a plate structure and/or made of water tube walls within which a gas, e.g. steam, and/or a liquid, e.g. water, flows for extracting heat from hot flue gases.

The flue gas channel 16 may include, positioned in one or more of the flue gas passages 60, one or more heat exchangers 20 for extracting heat from hot flue gases and for which the present solution may be applied. The purpose of the heat exchanger 20 varies, the heat being passed to a fluid, a gas, or steam flowing inside the heat exchanger 20. The heat exchanger 20 includes heat exchanger tubes 28 shown in Fig. 2 within which the fluid, gas, or steam flows.

Referring to Fig. 2, one embodiment of the heat exchanger 20 which may be applied in the present solution is shown. The heat exchangers 20 of the flue gas channel 16 may include one or more superheaters for superheating steam circulating in the water and steam circulation system of the boiler 10, one or more reheaters for reheating steam, one or more heat exchangers of a boiler bank for heating water-steam mixture, one or more preheaters, e.g. economizers, for preheating water fed to the water circulation system, and/or one or more air heaters for preheating air before feeding the air into the furnace 12.

Referring to Fig. 2, the flue gas passage 60 comprises walls enclosing a passage for hot flue gases, the walls including two side walls, a front wall 34 and a back wall 32 that according to an example are vertical.

Referring to Fig. 2, the above-mentioned one or more heat exchangers 20 may be supported on the front wall 34 and/or on the back wall 32.

Referring to Figs. 3 to 6, the heat exchanger 20 comprises at least two horizontal heat exchanger tubes 28 that are parallel and adjacent to each other. Preferably, there is a plurality of the horizontal heat exchanger tubes 28 in the heat exchanger. In Fig. 3 and 5 the horizontal heat exchanger tubes 28 are presented in a simplified manner by way of circular shapes.

Referring to Fig. 2, according to an example, the heat exchanger 20 comprises one or more elements each composed of at least two horizontal heat exchanger tubes 28 that are parallel, separated by a gap and on top of each other in a vertical direction. The heat exchanger tubes 28 may be connected at their ends by way of a curved tube section 36 in such a way that one or more, for example one to four, separate circuits, each with its own inlet and outlet is formed. The inlets may be connected to a common header reservoir 38 and the outlets may be connected to another header reservoir 40. The header reservoirs 38, 40 may communicate with the water and steam circulation system of the boiler 10.

The element represents a group of the horizontal heat exchanger tubes 28 or forms a part of the heat exchanger 20 or constitutes the heat exchanger 20.

According to the example shown in Fig. 2, the element comprises twentyfour horizontal heat exchanger tubes 28 on top of each other.

Referring to Figs. 3 and 5, according to an example, the heat exchanger 20 comprises two or more of the elements that are parallel and adjacent to each other in a horizontal direction in such a way that at least two pairs of the horizontal heat exchanger tubes 28 on top of each other in a vertical direction is formed. In the above-mentioned example, two of the adjacent elements form twenty-four pairs of the horizontal heat exchanger tubes 28 on top of each other. Similar type header reservoirs 38, 40 may be combined to form a common header reservoir.

Four or more of the above-mentioned elements form at least two pairs of the horizontal heat exchanger tubes 28 adjacent to each other in the horizontal direction.

Referring to Fig. 2, the heat exchanger 20 is supported on at least one vertical support tube 30, also known as a stringer tube or a hanger tube. One embodiment of the vertical support tube 30 which may be applied in the present solution is shown in Figs. 2 to 6.

Referring to Figs. 3 to 5, the at least one vertical support tube 30 may pass through the exchanger 20 in such a way that it extends in a vertical direction and it is located between the adjacent horizontal heat exchanger tubes 28 of the pairs on top of each other.

The vertical support tube 30 provides additional supporting forces for holding up loads incurred by the heat exchanger tubes 28. According to an example, between the front and back walls 32, 34 the heat exchanger 20 is supported on the at least one vertical support tube 30. For example, a middle section of the heat exchanger 20 is supported on the at least one vertical support tube 30.

According to an example, for improved service life, the vertical support tube 30 is cooled by means of a liquid or gas flowing inside the vertical support tube 30. The vertical support tube 30 may communicate with the water and steam circulation system of the boiler 10. The vertical support tube 30 may be top supported, for example supported, by a suspension arrangement, to the flue gas channel 16 or to the support frame 18, and/or bottom-supported, for example supported by a header reservoir connected to the vertical support tube 30. According to an example the vertical support tube 30 is circular and/or formed by a circular pipe. The vertical support tube 30 is made for example from weldable steel.

A support element 42 according to the solution is shown in Figs. 3 and 5. Two embodiments of the support element 42 which may be applied in the present solution are shown in Figs. 3 to 10.

The support element 42 is configured to support at least one of the horizontal heat exchanger tubes 28. The support element 42 is configured to be mounted on the vertical support tube 30.

Alternatively, or additionally, the support element 42 is configured to support at least one pair of the horizontal heat exchanger tubes 28 that are parallel and adjacent to each other in a horizontal direction, e.g. one of the above- mentioned pairs. The support element 42 is configured to be mounted on the vertical support tube 30. Thereby the support element 42 is between the adjacent horizontal heat exchanger tubes 28 of the pair.

Referring to examples shown in Figs. 7 to 10, the support element 42 comprises a main body 44 and at least one supporting arm 46 or at least one pair of the supporting arms 46.

The main body 44 includes a hollow interior that extends in a vertical direction through the main body 44. The main body 44 is configured to surround the vertical support tube 30 that passes through the hollow interior. The main body 44 may be in the form of a sleeve.

The supporting arm 46 extends outwardly from and substantially perpendicular to the main body 44. Each pair of the supporting arms 46 comprises two supporting arms 46 that extend in two opposite directions with respect to each other.

Each supporting arm 46 is configured to support at least one of the heat exchanger tubes 28 in such a way that in a vertical direction a downward movement of the heat exchanger tube 28 is prevented. Referring to the examples in Figs. 4 and 6, the shape of the hollow interior of the support element 42 may be configured to allow the support element 42 to rotate around a vertical direction about the vertical support tube 30. According to an example shown in Figs. 4 and 8, the shape is circular, or circular in part as in the example of Figs. 6 and 10.

Referring to the examples in Figs. 4 and 6, the shape of the hollow interior of the support element 42 may be configured to allow the support element 42 to slide along the vertical support tube 30. According to an example shown in Figs. 4 and 8, the shape is circular, or circular in part as in the example of Figs. 6 and10.

Preferably, the rotating movement and/or the sliding movement enables the mounting of and facilitates the installation of the support element 42 and/or the horizontal heat exchanger tubes 28 or are for use during the installation.

According to an example in Figs. 3 and 5, one of the supporting arms 46, when being installed in place, is adapted to extend into each above-mentioned gap separating two of the horizontal heat exchanger tubes 28 that are parallel and on top of each other in a vertical direction.

According to a first example the main body 44 is formed by a circular pipe as shown in Figs. 7 and 8. The main body 44 is made for example from weldable steel. According to the first example each supporting arm 46 is a sheet structure fixed to the main body 44. The supporting arms 46 are made for example from weldable steel.

According to a second example the main body 44 is formed by two support element parts as shown in Figs. 9 and 10. Each support element part includes a curved section constituting a part of the main body 44. At least one of the support element parts includes one or more of the supporting arms 46 integrated to the curved section.

According to an example, only one of the support element parts includes the curved section. According to an example, in a horizontal plane the cross section of at least one of the support element parts includes a first section and a second section that are transverse to each other and constitute the curved section.

According to an example, in a horizontal plane the cross section of at least one of the support element parts includes a first section and a second section that are transverse to each other and constitute a part of the main body 44. For example, the first and second sections are at an angle to each other and/or form a corner.

In the examples above, the one or more supporting arms 46 are extensions of the second section. The one or more supporting arms 46 are separated from the first section by the second section.

The two support element parts are connected to each other, e.g. by welding, to form the main body 44 and the supporting arms 46. The hollow interior of the support element 42 is formed between the two support element parts. The support element parts are made for example from weldable steel.

According to an example in Figs. 9 and 10, at least one of the support element parts constitutes a bent metal plate.

According to an example in Figs. 9 and 10, in a horizontal plane the cross section of at least one of the support element parts imitates the shape of the capital letter “L” or “J”.

Referring to the examples in Figs 3 and 5, when the support element 42 comprises at least two pairs of the supporting arms 46, the pairs are one after the other in a vertical direction and the supporting arms 46 extend in the above- mentioned two opposite directions on two opposite sides of the support element 42. When the support element 42 comprises two or more of the supporting arms 46 one after the other in a vertical direction, the supporting arms 46 extend in the same direction on a side of the support element 42.

According to examples, the supporting arms 46 are on one side of the support element 42 only or on two opposite sides of the support element 42 only. Preferably, the spacing of the supporting arms 46 is matched with the spacing of the horizontal heat exchanger tubes 28 in the heat exchanger 20 or in the above-mentioned elements of the heat exchanger 20, as shown in Figs. 2, 3 and 5.

Referring to Figs 7 and 9, each supporting arm 46 may include a retaining lip at an outer end of the supporting arm 46, the retaining lip extending upwardly from the outer end of the supporting arm 46.

Referring to Figs 7 and 9, each supporting arm 46 may have a recess for supporting from below one of the heat exchanger tubes 28 that is located in the recess. The recess may be rounded.

According to an example, the retaining lip extends to a height that is equal to or less than the radius of the horizontal heat exchanger tube 28 that is supported by the supporting arm 46 and has a circular shape.

According to an example, the outer end of the supporting arm 46 is shaped to engage a matching shape on one of the heat exchanger tubes 28. The supporting arm 46, when connected to the matching shape, supports the heat exchanger tube 28.

According to an example, the supporting arm 46, e.g. the lip, the recess, and/or the shape of the supporting arm 46, is configured to support at least one of the heat exchanger tubes 28 in such a way that in a horizontal direction a lateral movement of the heat exchanger tube 28 away from the support tube 30 and off the supporting arm 46 is prevented. In an example, the lateral movement is perpendicular to the heat exchanger tube 28.

According to an example, in a vertical direction an upward movement of the heat exchanger tube 28 is necessary to move the heat exchanger tube 28 off the supporting arm 46. According to an example, the upward movement is equal to or more than, or, equal to or less than the height of the heat exchanger tube 28. According to another example, the upward movement is less than the height of the above-mentioned gap separating the heat exchanger tubes 28. According to an example in Figs. 3 and 5, when being installed in place on the supporting arms 46, the heat exchanger tubes 28 of the heat exchanger 20 or an element of it are adapted to be moved off the supporting arms 46. This takes place by means of the upward movement or the lateral movement, or a combination of these. The movements are relative in such a way that either the heat exchanger tube 28 or the supporting arm 46, or both, moves.

According to another example in Figs. 3 to 6, when being installed in place on the supporting arms 46, the heat exchanger tubes 28 of the heat exchanger 20 or an element of it are adapted to be moved off the supporting arms 46 by means of the upward movement or the lateral movement as mentioned above, or a rotational movement of the support element 42 together with the supporting arms 46, or a combination of at least two of these movements.

According to an example, to facilitate the above-mentioned movements, the supporting arms 46 are separate from the heat exchanger tubes 28. For example, welds are not provided to connect the supporting arms 46 to the heat exchanger tubes 28.

According to an example, the above-mentioned heat exchanger tubes 28 are, at the location of the supporting arms 46, continuously adapted to be freely moved off the supporting arms 46. For example, there are no locking arrangements or clamping elements keeping the heat exchanger tubes 28 on the supporting arms 46 and being removed when the heat exchanger tubes 28 are being replaced.

Referring to the examples in Figs 7 and 9, in each pair of the supporting arms 46, the supporting arms 46 are preferably parallel to each other and in a vertical direction located at the same height.

Referring to Figs. 3 and 5, the heat exchanger 20 may be supported by one support element 42, or, by at least two support elements 42 on top of each other. In the latter case, the support elements 42 may be separated by a gap or the upper support element 42 rests on the lower support element 42. The one support element 42, the lower support element 42, or the lowest support element 42 may be attached to the vertical support tube 30, for example to prevent the support element(s) 42 from sliding down along the vertical support tube 30. Preferably, the support element 42 is supported by the vertical support tube 30 when being connected to it or by way of another support element 42 or a component attached the vertical support tube 30.

Referring to the examples in Figs. 3 and 5, there may be a bracket 48 that is fixed, e.g. by welding, to the vertical support tube 30 below the support element(s) 42. The bracket 48 is adapted to support the support element(s) 42 and to prevent the support element(s) 42 from sliding down along the vertical support tube 30. According to an example, one of the support elements 42 rests on the bracket 48. The bracket 48 may be in the form of a circular ring or sleeve. The support element 42 or the lowermost support element 42 may be fixed, e.g. by welding, to the bracket 48, for preventing the support element 42 from rotating about the vertical support tube 30.

Referring to the example in Fig. 9, the support element 42 may be prevented from rotating with respect to the other corresponding support elements 42, around a vertical direction, and/or around the vertical support tube 30.

As shown in an example in Fig. 9, for the above-mentioned reasons, the main body 44 of the support element 42 comprises a protrusion or a notch in a lower section and/or in an upper section of the main body 44. The protrusion and/or the notch is adapted to settle against a matching protrusion or a matching notch of another one of the support elements 42, the other support element 42 being situated in a vertical direction above or below the support element 42. The protrusion and the notch are configured to prevent the support element 42 from rotating, with respect to the other support element 42, around a vertical direction, and/or the vertical support tube 30.

The support element 42 may comprise one or more clamping elements 50 mounted on the support element 42 for tying one or more horizontal heat exchanger tubes 28 to the support element 42 and/or to prevent the support element 42 from rotating around the vertical support tube 30. The clamping element 50 is preferably detachable.

Referring to the example shown in Figs. 3, 5, 11 and 12, there may be a clamping element 50 mounted on the main body 44 of the support element 42, for the purpose of preventing the support element 42, or the uppermost support element 42, from rotating around the vertical support tube 30. The clamping element 50 may lean against one or two of the horizontal heat exchanger tubes 28.

According to an example, as shown in Figs. 3, 5, 11 and 12, the clamping element 50 extends over at least one of the horizontal heat exchanger tubes 28 to at least one of the supporting arms 46 on which the at least one horizontal heat exchanger tube 28 is supported. The clamping element 50 engages the at least one supporting arm 46.

According to an example in Figs. 3 and 5, a plurality of or at least one of the heat exchanger tubes 28 of the above-mentioned element, excluding at least one uppermost horizontal heat exchanger tube 28 of the element, are freely movable as explained above. This is because there may be a locking arrangement or a clamping element, e.g. the locking element 50, tying at least one of the horizontal heat exchanger tubes 28, e.g. the at least one uppermost horizontal heat exchanger tube 28. The uppermost one of the horizontal heat exchanger tubes 28 is additionally excluded as a special case because there may be no supporting arm 46 above it.

This facilitates the removal or replacement of the above-mentioned element because only some of the horizontal heat exchanger tubes 28, e.g. the at least one uppermost heat exchanger tube 28, are necessary to be released, i.e. removing the locking arrangement or the clamping element.

According to an example in Figs. 11 and 12, the clamping element 50 comprises a cover part 56 adapted to be mounted on the main body 44. The cover part 56 has an opening 52 through which the vertical support tube 30 extends and at least one skirt part 58 including a notch 54 adapted to engage the supporting arm 28. The clamping element 50 is made for example from weldable steel.

The support element 42 may comprise a bracket attached to it and which the clamping element 50, for example the cover part 56, engages. For example, the opening 52 may have a notch that settles on the bracket. Referring to Figs. 4 and 6, the support element 42 being rotatably mounted on the vertical support tube 30, the installation of the support element 42 between the horizontal heat exchanger tubes 28, the removal of the support element 42 from between the horizontal heat exchanger tubes 28, the installation of the heat exchanger 20 or one or more elements of the heat exchanger 20 into the flue gas passage 60, and the removal of the heat exchanger 20 or one or more elements of the heat exchanger 20 from the flue gas passage 60 is facilitated.

This facilitation is realized by rotating the support element 42 in such a way that the supporting arms 46 of the support element 42 reach a position in which they are parallel, or substantially parallel, to the horizontal heat exchanger tubes 28. This, for example, prevents the supporting arms 46 from colliding with the heat exchanger tubes 28 that are being moved. This rotational movement turns the supporting arms 46 away from the horizontal heat exchanger tubes 28.

This facilitation is additionally realized by the above-mentioned upward movement, the lateral movement, or the rotational movement, or a combination of at least two of them.

One or more of the above-mentioned movements are utilized in a method in the flue gas passage 60 of the boiler 10 for removing or replacing the horizontal heat exchanger tubes 28 of the group, the element, or the heat exchanger 20 as described above from the flue gas passage 60.

In the method, the support element 42 or all the support elements 42 are rotated around a vertical direction about the vertical support tube 30, i.e. the rotational movement is applied. The supporting arms 46 turn away from the horizontal heat exchanger tubes 28, thereby moving the horizontal heat exchanger tubes 28 off the supporting arms 46.

In a later step of the method the horizontal heat exchanger tubes 28 are moved from the flue gas passage 60. According to an example, the moving is brought about by moving the horizontal heat exchanger tubes 28 horizontally in a direction substantially parallel to the horizontal heat exchanger tubes 28. When two or more of the horizontal heat exchanger tubes 28 are connected at their ends by way of one or more of the curved tube section 36, the supporting arms 46 avoid colliding with the curved tube section 36 while being turned away as described above and being moved from the flue gas passage 60.

According to an example, the rotational movement is supplemented by moving the horizontal heat exchanger tubes 28 off the supporting arms 46 by means of the upward movement or the lateral movement, or both of these movements, as described above.

According to an example, the clamping element 50 as described above is applied on the support element 42 for tying the horizontal heat exchanger tubes 28 to the support element 42. For example, at least one of the uppermost horizontal heat exchanger tubes 28 is tied to the support element 42. In the method, the clamping element 50 is removed before the step of the rotational movement, for allowing the support element 42 to rotate.

In this description, the singular form “a”, “an”, and “the” referring to a device or component does not exclude additional or a plurality of corresponding devices or components, unless where specifically specified.

In the description, various devices and components may be described as “comprising” other components. The terms “comprise(s)”, “comprising”, “include(s)”, “having”, “has”, and variants thereof, are intended to be open- ended phrases that do not exclude the possibility of additional components, unless where specifically specified.

The various aspects and embodiments of the present solution disclosed in this description are for the purposes of illustration and are not intended to be limiting. It is intended that the present solution be construed as including all such aspects and embodiments that are covered by the scope of the appended claims.