Wall for fluidized bed boiler and fluidized bed boiler

Abstract

A wall for a fluidized bed boiler. The wall comprises: a first heat exchanger tube comprising a first primary portion and a first secondary portion; a second heat exchanger tube includes a second primary portion and a second secondary portion. A first gap is arranged between the first secondary portion and the second secondary portion, at least a portion of the first secondary portion and at least a portion of the second secondary portion extending linearly in parallel in an imaginary plane. The wall is configured to enable particulate material to be spread through the first gap from a first side of the plane to an opposite second side of the plane. The wall includes a refractory material disposed on at least one side of a portion of the first secondary portion and a portion of the second secondary portion. A fluidized bed boiler includes a wall. According to the scheme of the utility model, the erosion on the heat exchanger tube of the wall of the fluidized bed boiler, especially the erosion near the refractory material, can be reduced.

Description

Technical Field

[0001] The utility model relates to a fluidized bed boiler. The utility model relates to a wall of a fluidized bed boiler. The utility model relates to a partition wall of a fluidized bed boiler. Background Art

[0002] In a fluidized bed boiler, the bed material (which usually includes sand) is in a fluidized state. Typically, the wall of a fluidized bed boiler includes heat exchanger tubes that define a furnace to recover heat from the furnace. These heat exchanger tubes are connected to each other by fins or similar connectors to form an airtight wall structure. As a result of fluidization, the bed material usually flows downward in a furnace close to the wall of the boiler. If the wall includes a protrusion or a bend, the flowing bed material may easily erode the heat exchanger tube. For example, it is known from WO2018 / 158497 that in such a scheme, the erosion of the heat exchanger tube can be reduced by providing a circumferentially extending metal coating to the heat exchanger tube. The thickness of the coating and the diameter of the coated portion of the tube are selected so that the diameter of the coated portion is at most equal to the diameter of the uncoated portion. A plurality of fins are continuously welded to such a heat exchanger tube to form the above-mentioned wall. A portion of this wall can be covered by a refractory material.

[0003] It is now recognized that near the interface of the refractory material with the heat exchanger tube, the refractory material interferes with the flow of the bed material, which, as mentioned above, occurs near the wall. As a result, the bed material flowing downward overlaps the surface of the refractory material, which interferes with the bed material flow. It has been found that highly localized erosion occurs near the refractory material. Unless maintenance is performed, this erosion may lead to small holes or pores in the heat exchanger tubes, which in turn may lead to failure of the entire boiler. The size of these holes or pores may, for example, be in the range of 5-20 mm x 5-20 mm.

[0004] Therefore, there is a need to reduce the erosion experienced by heat exchanger tubes of such wall structures, particularly in the vicinity of the refractory material. Utility Model Content

[0005] Without wishing to be bound by theory, the inventors believe that the highly localized erosion is the result of a vortex of bed material forming near the interface of the refractory material to the wall of the heat exchanger tube. The formation of the vortex is described as Figure 9a and Figure 9b In typical use, Figure 9a The direction towards the reader is vertical (in Figure 9b Therefore, if Figure 9a and Figure 9bAs shown, on the side of the furnace, the downwardly flowing bed material (which flows along the wall formed by the tubes) forms a plurality of eddies in the vicinity of the refractory material when it strikes the surface of the refractory material. These eddies appear to be the cause of highly localized erosion of the heat exchanger tubes of the wall. Thus, as described above, holes or pores may erode these tubes.

[0006] The inventors have found that such erosion of the heat exchanger tubes can be reduced by: (i) increasing the size of the vortices; or (ii) by forming a wall structure that does not produce such vortices. Consistent with this finding, when the wall does not include fins near the interface between the refractory material and the heat exchanger tubes, the bed material and gas can propagate deeper between these heat exchanger tubes, thereby providing a much larger space for the vortices. This wall structure is more specifically disclosed in the first embodiment of the present invention. According to the first embodiment of the present invention, a wall for a fluidized bed boiler is provided, the wall comprising: a first heat exchanger tube, comprising a first primary portion and a first secondary portion; a second heat exchanger tube, arranged in parallel with the first heat exchanger tube, the second heat exchanger tube comprising a second primary portion and a second secondary portion; a first connector, fixed to the first primary portion and to the second primary portion; and a first gap, located between the first secondary portion and the second secondary portion. wherein at least a portion of the first secondary portion and at least a portion of the second secondary portion extend in parallel and straight within an imaginary plane, and at least a portion of the first gap penetrates the plane so that particulate material can be dispersed from a first side of the plane to an opposite second side of the plane through the first gap, and the wall comprises: a refractory material arranged on at least one side of a portion of the first secondary portion and a portion of the second secondary portion so that a portion of the first secondary portion extends from the refractory material to a first direction, a portion of the second secondary portion extends from the refractory material to the first direction, and the first gap extends from the refractory material to the first direction. wherein the outer diameter of the first secondary portion is less than or equal to the outer diameter of the first primary portion, the outer diameter of the second secondary portion is less than or equal to the outer diameter of the second primary portion, and the first direction forms an angle of at most 30 degrees with an upward vertical direction.

[0007] In addition, the inventors have found that erosion of heat exchanger tubes of such wall structures caused by vortices can be reduced by reducing the tendency to form any vortices. Consistent with this finding, when the wall does not include fins near the interface between the refractory material and the heat exchanger tube, and the bed material and gas can pass through the wall and spread to the other side of the wall, the tendency to form any vortices is reduced. Such a wall structure is more specifically disclosed in the second embodiment of the utility model. According to the second embodiment of the utility model, the wall includes: a third heat exchanger tube, arranged in parallel with the second heat exchanger tube, the third heat exchanger tube including a third primary part and a third secondary part; a second connecting member, fixed to the second primary part and fixed to the third primary part; and a second gap, located between the second secondary part and the third secondary part. wherein at least a portion of the first secondary portion, at least a portion of the second secondary portion, and at least a portion of the third secondary portion extend in parallel and straight within the plane, and at least a portion of the second gap penetrates the plane, so that particulate material can be spread from the first side of the plane to the opposite second side of the plane through the first gap, and return from the second side of the plane to the first side of the plane through the second gap. wherein a portion of the third secondary portion extends from the refractory material to the first direction, and the second gap extends from the refractory material to the first direction. according to this second scheme, it is preferred that the wall is configured so that particulate material can reach the second gap from the first gap bypassing the second secondary portion on the second side of the plane; it is more preferred that the outer diameter of the third secondary portion is less than or equal to the outer diameter of the third primary portion.

[0008] According to the third embodiment of the present invention, a fluidized bed boiler is provided, which includes: a furnace; an air nozzle for allowing combustion air to enter the furnace; a fuel inlet for allowing fuel to enter the furnace; and a wall according to the first or second embodiment of the present invention, wherein the wall defines the furnace so that at least the first side of the plane is exposed to a portion of the furnace. According to the third embodiment, it is preferred that the fluidized bed boiler includes a particle separator, which is used to separate particulate material from the flow received from the furnace so that at least some of the separated particulate material is returned to the furnace.

[0009] According to the fourth scheme of the present utility model, the first part of the furnace in the fluidized bed boiler is arranged on a first side of the wall, and the second part of the furnace is arranged on an opposite second side of the wall, the first part of the furnace is provided with a first group of air nozzles, and the first group of air nozzles are used to fluidize the bed material in the first part of the furnace, and the second part of the furnace is provided with a second group of air nozzles, and the second group of air nozzles are used to fluidize the bed material in the second part of the furnace.

[0010] According to a fifth embodiment of the present invention, the fluidized bed boiler includes: a suspension structure including an upper beam; a support structure including a lower beam; and a grate arranged above the support structure, wherein the grate includes the first group of air nozzles and the second group of air nozzles, the wall is fixed to the suspension structure, the wall supports the support structure, the support structure supports the grate, the first heat exchanger tube and the second heat exchanger tube of the wall extend in a straight line between the suspension structure and the support structure, and the first direction forms an angle of at most 5 degrees with the upward vertical direction.

[0011] According to a sixth aspect of the present invention, the furnace in the fluidized bed boiler includes a primary part of the furnace and a secondary part of the furnace, the secondary part of the furnace has a downwardly tapered shape, the primary part of the furnace is arranged above the secondary part of the furnace, and the first gap is arranged in the primary part of the furnace. According to the sixth aspect, it is preferred that an imaginary dividing plane forms an interface between the primary part of the furnace and the secondary part of the furnace, and (A) the side wall of the furnace includes a curved line arranged on the imaginary dividing plane, and the imaginary dividing plane has a vertical normal, or (B) two opposite side walls of the furnace include curved lines arranged on the imaginary dividing plane.

[0012] Other preferred embodiments of the wall are disclosed in the seventh to fourteenth aspects of the present invention.

[0013] According to the seventh embodiment of the present invention, in a wall or fluidized bed boiler, the body of the first secondary part has a first contour shape extending in the longitudinal direction of the first secondary part, so that the first contour shape has a constant outer diameter over the entire length of the first secondary part, and the length of the first secondary part is greater than zero, the body of the second secondary part has a second contour shape extending in the longitudinal direction of the second secondary part, so that the second contour shape has a constant outer diameter over the entire length of the second secondary part, and the length of the second secondary part is greater than zero, only a portion of the first secondary part is covered by the refractory material, thereby a portion of the first secondary part defines the first gap, and only a portion of the second secondary part is covered by the refractory material, thereby a portion of the second secondary part defines the first gap.

[0014] According to an eighth aspect of the present invention, in a wall or fluidized bed boiler, the first heat exchanger tube includes a first primary connecting portion connecting the first primary portion to the first secondary portion, and the second heat exchanger tube includes a second primary connecting portion connecting the second primary portion to the second secondary portion.

[0015] According to the ninth embodiment of the present invention, in a wall or fluidized bed boiler, it includes: a first coating arranged on at least a portion of the first secondary portion; and a second coating arranged on at least a portion of the second secondary portion, so that at least a portion of the first coating extends from the refractory material to the first direction on the first secondary portion, and completely surrounds at least a portion of the first secondary portion laterally, thereby at least a portion of the first coating defines the first gap, and at least a portion of the second coating extends from the refractory material to the first direction on the second secondary portion, and completely surrounds at least a portion of the second secondary portion laterally, thereby at least a portion of the second coating defines the first gap. Wherein, the first coating includes metal or ceramic, and the second coating includes metal or ceramic. According to the ninth embodiment, it is preferred that the wall includes the third heat exchanger tube according to the second embodiment, thereby at least a portion of the second coating defines the second gap.

[0016] According to a tenth aspect of the present invention, in a wall or fluidized bed boiler, a portion of the first coating is arranged laterally between the body of the first secondary part and the refractory material, and a portion of the second coating is arranged laterally between the body of the second secondary part and the refractory material.

[0017] According to an eleventh aspect of the present invention, in a wall or fluidized bed boiler, the first coating layer comprises a metal alloy and is a cladding, and the second coating layer comprises a metal alloy and is a cladding.

[0018] According to a twelfth aspect of the present invention, in a wall or fluidized bed boiler, the thickness of the first coating is 1 mm to 4 mm, preferably 2 mm to 3 mm, and the thickness of the second coating is 1 mm to 4 mm, preferably 2 mm to 3 mm.

[0019] According to the thirteenth scheme of the utility model, in a wall or fluidized bed boiler, the first heat exchanger tube includes a first tertiary section, so that the first secondary section is arranged between the first primary section and the first tertiary section. Wherein, the inner diameter of the first tertiary section is greater than the inner diameter of the first secondary section, and the second heat exchanger tube includes a second tertiary section, so that the second secondary section is arranged between the second primary section and the second tertiary section. Wherein, the inner diameter of the second tertiary section is greater than the inner diameter of the second secondary section. According to the thirteenth scheme, it is preferred that the inner diameter of the first tertiary section is equal to the inner diameter of the first primary section, and the inner diameter of the second tertiary section is equal to the inner diameter of the second primary section; and it is preferred that the outer diameter of the first tertiary section is equal to the outer diameter of the first primary section, and the outer diameter of the second tertiary section is equal to the outer diameter of the second primary section; and it is preferred that at least a portion of the first tertiary section is covered by the refractory material, and at least a portion of the second tertiary section is covered by the refractory material.

[0020] According to a fourteenth aspect of the present utility model, in a wall or fluidized bed boiler, the first secondary part is not provided with one or more fins, and the second secondary part is not provided with one or more fins.

[0021] The wall is preferably a wall of a circulating fluidized bed boiler as described in detail in the third to sixth embodiments of the present invention and the fifteenth embodiment of the present invention described below. According to the fifteenth embodiment of the present invention, in the fluidized bed boiler, the first part of the furnace is arranged on the first side of the wall, and the second part of the furnace is arranged on the opposite second side of the wall, so that the second side of the plane is exposed to the second part of the furnace; the first part of the furnace is provided with an air nozzle, which is used to fluidize the bed material in the first part of the furnace, and the second part of the furnace has no air nozzle. In addition, the fluidized bed boiler includes a plate, at least a portion of which is arranged on the second side of the plane. Wherein, the plate is fixed to the first connecting member and is configured to prevent the bed material from escaping from the furnace.

[0022] According to a sixteenth aspect of the present invention, in a wall or fluidized bed boiler, the first secondary part is coaxial with the first primary part, and the second secondary part is coaxial with the second primary part.

[0023] Furthermore, the wall is preferably a partition wall of a furnace of a circulating fluidized bed boiler, as described in detail in the third to sixth aspects of the present invention above.

[0024] These and other embodiments are further described in the description and drawings.

[0025] The beneficial technical effects of the solution of the utility model include that the erosion of the heat exchanger tubes of the wall structure of the fluidized bed boiler can be reduced, especially the erosion near the refractory material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Some of the figures in the accompanying drawings show different views of various embodiments of the present invention. These different views / details have been labeled close to the figure number of the figure. Thus, for example, Figure 1a of the accompanying drawings shows the view / detail Ia of Figure 1b. This is indicated by the label "(Ia)" close to the figure number "Figure 1a". In line with this, the text "Figure 1a (Ia)" can be seen on the figure on page 1. Similar labeling is used in other figures, as described in detail below.

[0027] FIG. 1a shows a wall for a fluidized bed boiler in a side view Ia, which is indicated in FIG. 1b ,

[0028] FIG. 1 b shows the wall for the fluidized bed boiler of FIG. 1 a in a front view I b, which is indicated in FIG. 1 a ,

[0029] FIG. 1c shows the wall for the fluidized bed boiler of FIG. 1a and FIG. 1b in a first top view Ic, which is indicated in FIG. 1b ,

[0030] FIG. 1d shows the wall for the fluidized bed boiler of FIG. 1a and FIG. 1b in a second top view Id, which is indicated in FIG. 1b ,

[0031] FIG. 2a shows a portion of a wall for a fluidized bed boiler, which portion does not include the refractory material 230 of FIGS. 1a to 1d , in a side view IIa, which is indicated in FIG. 2b .

[0032] FIG. 2 b shows a portion of a wall for a fluidized bed boiler, which portion does not include the refractory material 230 of FIGS. 1 a to 1 d , in a front view II b, which is indicated in FIG. 2 a .

[0033] FIG. 2 c shows the portion of the wall for the fluidized bed boiler of FIG. 2 a and FIG. 2 b in a top view II c, which is indicated in FIG. 2 b .

[0034] FIG. 2d shows the portion of the wall for the fluidized bed boiler of FIG. 2a and FIG. 2b in a top view IId, which is indicated in FIG. 2b .

[0035] Figure 2e A portion of the wall of a heat exchanger tube provided with a coating (119, 129, 139) and the outer diameter of the heat exchanger tube in this case are shown in a top view IId, which is indicated in FIG. 2b,

[0036] Figure 3a A circulating fluidized bed boiler with walls is shown in side view,

[0037] FIG. 3b shows a circulating fluidized bed boiler from a top view IIIb. Figure 3a Indicated in the middle,

[0038] Figure 3c Another side view shows Figure 3a Circulating fluidized bed boiler,

[0039] Figure 4a The wall for a fluidized bed boiler is shown in front view,

[0040] FIG. 4 b shows a wall for a fluidized bed boiler in a top view IVb. Figure 4a Indicated in the middle,

[0041] Figure 4c The wall for a fluidized bed boiler is shown in front view,

[0042] Figure 4d The wall for a fluidized bed boiler is shown in front view,

[0043] Figure 5a A circulating fluidized bed boiler with walls is shown in side view,

[0044] Figure 5b shows in more detail Figure 5a Details of Vb,

[0045] FIG. 5 c shows a portion of a wall for a fluidized bed boiler from a top view V c denoted in FIG. 5 b ,

[0046] Figure 6 A wall with refractory material tapering upwards is shown in a similar perspective to FIG. 1a,

[0047] Figure 7aA circulating fluidized bed boiler having a wall comprising two mutually perpendicular planar portions is shown in a side view.

[0048] FIG. 7b shows a top view of the Figure 7a The wall of the circulating fluidized bed boiler,

[0049] FIG. 8a shows a wall for a fluidized bed boiler, the wall including wings, in a front view VIIIa, which is indicated in FIG. 8c ,

[0050] FIG. 8 b shows the wall for the fluidized bed boiler of FIG. 8 a in a top view VIII b, which is indicated in FIG. 8 a .

[0051] FIG. 8c shows a portion of a wall for a fluidized bed boiler, the wall comprising a wing, in a side view VIIIc, which is indicated in FIG. 8a ,

[0052] Figure 8d A portion of a fluidized bed boiler is shown in side view, comprising a wall including wings,

[0053] Figure 8e A portion of a fluidized bed boiler is shown in side view, comprising a wall including wings,

[0054] Figure 8f A wall for a fluidized bed boiler is shown in elevation, the wall comprising wings,

[0055] FIG. 8g shows a top view VIIIg. Figure 8f The wall of a fluidized bed boiler, the top view VIIIg Figure 8f Indicated in the middle,

[0056] Figure 9a shows, from a top view, the known wall of a fluidized bed boiler and the vortices formed during use, and

[0057] Figure 9b A side view showing a vortex Figure 9a of known walls.

[0058] In these figures, directions Sx, Sy and Sz are three mutually orthogonal directions. In preferred use, direction Sz is opposite to gravity (ie, Sz is upward and vertical). DETAILED DESCRIPTION

[0059] The utility model relates to a fluidized bed boiler 300. Figure 3a to Figure 3c The fluidized bed boiler 300 is shown in a number of different viewing angles. Figure 3a to Figure 3c The fluidized bed boiler 300 is a circulating fluidized bed boiler. Figure 5aAnother fluidized bed boiler 300 is shown in FIG. The fluidized bed boiler 300 includes a furnace 310. The fluidized bed boiler 300 includes a plurality of walls. Some of the walls define the furnace 310. The partition wall can divide the furnace 310 into two parts so that combustion occurs on both sides. The utility model relates to a wall 200 of the fluidized bed boiler 300. The wall 200 can be a partition wall, such as Figure 3a to Figure 3c In this alternative, the wall 200 may be a side wall of the furnace 310, such as Figure 5a As shown in Fig. 5c. Naturally, the fluidized bed boiler may include both a wall 200 having a structure disclosed in detail below as a partition wall and another wall 200 having a structure disclosed in detail below as a side wall.

[0060] 1a to 1d show a wall 200 for a fluidized bed boiler from a plurality of different perspectives. Referring to FIGS. 1b to 1d, the wall 200 comprises a first heat exchanger tube 110 and a second heat exchanger tube 120. The purpose of the heat exchanger tubes 110, 120 is to recover heat from the furnace 310. In one embodiment, another purpose of the heat exchanger tubes 110, 120 is to carry mechanical loads. In one embodiment, another purpose of the heat exchanger tubes 110, 120 is to prevent material from escaping from the furnace. The first heat exchanger tube 110 comprises a first primary portion 111 and a first secondary portion 112. The second heat exchanger tube 120 is arranged in parallel with the first heat exchanger tube 110 and comprises a second primary portion 121 and a second secondary portion 122.

[0061] With regard to the terminology of these parts, and with reference to Figures 2c and 2d, the outer diameter d12 of the first secondary part 112 is less than or equal to the outer diameter d11 of the first primary part 111. In addition, the outer diameter d22 of the second secondary part 122 is less than or equal to the outer diameter d21 of the second primary part 121. In use, the first primary part 111 is arranged above the first secondary part 112, and the second primary part 121 is arranged above the second secondary part 122, as shown in Figures 1a, 1b, 2a and 2b. For the definition of direction Sz, see above. These features have the effect that bed material flowing downwardly (in the negative Sz direction) along the wall 200 does not form eddies at the boundary between the primary part (111, 121) and the secondary part (112, 122) because there is no protrusion when moving from one side of the primary part (111, 121) to one side of the secondary part (112, 122). It should also be noted that in one embodiment, the secondary portion (112, 122) is provided with an overlay. In this context, the outer diameter refers to the outer diameter of the overlay of the secondary portion when the overlay is provided, such as Figure 2e2d. If no coating is provided, the outer diameter refers to the outer diameter of the secondary part alone, as shown in FIG2d. As described above, this definition ensures that no eddy currents are generated even if a coating is provided. Preferably, the first secondary part 112 is coaxial with the first primary part 111; and the second secondary part 122 is coaxial with the second primary part 121. This ensures, in relation to their outer diameters, that the secondary parts (112, 122) do not protrude from the tubular curtain defined by the primary parts (111, 121).

[0062] 1b and 1c, the wall 200 includes a first connector, such as a first fin 211. In FIG. 1b and 1c, the first fin 211 is used as the first connector. However, as will be described in detail below, in an alternative, the auxiliary heat transfer surface 241 may be used as the first connector. In the following, unless otherwise specified, the first fin 211 is used as an example of the first connector.

[0063] The first fin 211 is fixed to the first primary part 111 and to the second primary part 121. The purpose of the first fin 211 is to connect the first heat exchanger tube 110 and the second heat exchanger tube 120 to improve the integrity of the wall 200. In addition, when the wall 200 is used as a side wall of the furnace 310, the first fin 211 prevents gas and bed material from escaping from the furnace 310 between the first primary part 111 and the second primary part 121.

[0064] In a more general case, a first connector (e.g., first fin 211 or first auxiliary heat transfer surface 241) is fixed to the first primary portion 111 and to the second primary portion 121. The purpose of the first connector is to join the first heat exchanger tube 110 with the second heat exchanger tube 120 to improve the integrity of the wall 200. In addition, when the wall 200 is used as a side wall of the furnace 310, the first connector prevents gas and bed material from escaping from the furnace 310 between the first primary portion 111 and the second primary portion 121.

[0065] 1a and 1d, in the wall 200, at least a portion of the first secondary portion 112 and at least a portion of the second secondary portion 122 extend in parallel and in a straight line, and are located in an imaginary plane P. This plane P is imaginary, that is, it is not a physical object, but a plane known in the field of geometry. In one embodiment, at least the portion of the first secondary portion 112 and at least the portion of the second secondary portion 122 extend in parallel and in a straight line, so that the central axes of these portions belong to the plane P.

[0066] 1b and 1d, the wall 200 includes a first gap 221. The first gap 221 is arranged between the first secondary portion 112 and the second secondary portion 122. In FIG1a, the first gap 221 is arranged in front of the second secondary portion 122 (ie, the first gap 221 is from the second secondary portion 122 toward the reader).

[0067] The wall 200 is configured such that at least a portion of the first gap 221 penetrates the plane P, whereby gas and bed material can be dispersed through the first gap 221. Thus, the wall 200 is configured such that at least a portion of the first gap 221 penetrates the plane P, such that particulate material (i.e. bed material, and therefore also gas) can be dispersed (i.e. particulate material is able to be dispersed) through the first gap 221 from a first side S1 of the plane P to an opposite second side S2 of the plane P. Naturally, this feature is not a feature related to the particulate material itself that is arranged in the furnace 310 in use. In other words, there are no portions of the wall 200 that would prevent particulate material or gas from being dispersed through at least a portion of the first gap 221 and through the plane P from the first side S1 of the plane P to the opposite second side S2 of the plane P.

[0068] The spreading of particulate material (ie bed material) through at least a portion of the first gap 221 and across the plane P from a first side S1 of the plane P to an opposing second side S2 of the plane P is shown by arrow AR1 in FIG. 1 d .

[0069] It has been found that when the particulate material (i.e., bed material) is spread in this manner, if a vortex is formed in the first gap 221, the vortex spreads over a much larger area and causes less erosion of the heat exchanger tubes. For example, if the secondary portions 112, 122 of the heat exchanger tubes are formed by a plate (not shown) on the second side S2 instead of Figure 9a fins connected, this vortex can be formed. Naturally, Figure 9a The fins prevent the particulate material (ie bed material) from spreading from a first side of the wall to the opposite second side of the wall, as this is one of the main tasks of the fins.

[0070] In addition, the wall 200 includes a refractory material 230. The refractory material 230 is arranged on at least one side of a portion of the first secondary portion 112 and a portion of the second secondary portion 122 at the same time. Preferably, the refractory material 230 is arranged on both sides of a portion of the first secondary portion 112 and a portion of the second secondary portion 122. Therefore, in an embodiment, a portion of the refractory material 230 laterally surrounds a portion of the first secondary portion 112 and a portion of the second secondary portion 122. The function of the refractory material 230 is to protect the portion of the first secondary portion 112 and the portion of the second secondary portion 122. In order to protect the secondary portions 112 and 122, the thickness of the refractory material is preferably 25mm to 100mm. In this article, the thickness refers to the thickness of the refractory material on the first secondary portion 112; that is, the thickness of the refractory material between the open space of the furnace 310 and the outer surface of the first secondary portion 112. The top surface of the refractory material 230 can be flat and horizontal, as shown in Figure 1a. However, in order to facilitate the flow of the granular material, the refractory material may have an upwardly tapered shape, e.g. Figure 6 5b. In these figures, the top surface of the refractory material 230 includes an inclined portion.

[0071] In the wall 200, a portion of the first secondary portion 112 extends from the refractory material 230 to the first direction Dir1, a portion of the second secondary portion 122 extends from the refractory material 230 to the first direction Dir1, and a first gap 221 extends from the refractory material 230 to the first direction Dir1. The first direction Dir1 is the direction of the plane P and is perpendicular to a direction pointing from a first point on the central axis of the first secondary portion 112 to a second point on the central axis of the second secondary portion 122, wherein the second point is located on the central axis of the second secondary portion 122 and is the point closest to the first point. The first direction Dir1 is more or less preferably vertically upward, as described in more detail below. Therefore, the first gap 221 is arranged to such a position: at this position, highly localized erosion will occur in the absence of the first gap 221. One possible reason is the formation of highly localized vortices. Such a position in Figure 9a and Figure 9b However, providing more space for such eddies will result in less local erosion. Therefore, as shown in FIG. 1a, FIG. 1b and FIG. 1d according to this embodiment, the first gap 221 is arranged at a similar position to prevent the formation of eddies or at least increase the size of the eddies.

[0072] Consistent with the above, in one embodiment, the first secondary portion 112 is not provided with one or more fins, whereby the shape of the outer contour of the cross section of the body of the first secondary portion 112 is circular over the entire length of the first secondary portion 112. In addition, in one embodiment, the second secondary portion 122 is not provided with one or more fins, whereby the shape of the outer contour of the cross section of the body of the second secondary portion 122 is circular over the entire length of the second secondary portion 122. In this document, if the (first, second...) secondary portion (112, 122) is not provided with the (first, second...) coating 119, 129, the term "body" refers to the (first, second...) secondary portion (112, 122). However, if the (first, second ...) secondary part (112, 122) includes a (first, second ...) coating (119, 129), the term "body" refers to the (first, second ...) secondary part (112, 122) without the (first, second ...) coating (119, 129). Typically, if a coating is used, the coating is made of a different material than the body.

[0073] Referring to Figure 1d, it has also been found that when the particulate material can return to the first side S1 through another gap, no eddy currents are generated at all, or at least the tendency to form such eddy currents is significantly reduced. Thus, a more preferred embodiment of the wall includes a third heat exchanger tube 130 that defines a second gap 222 through which the particulate material can return, as described below. The path of the bed material through the two gaps is shown by arrow AR2 in Figure 1d.

[0074] In this embodiment, the third heat exchanger tube 130 is arranged in parallel with the second heat exchanger tube 120 and includes a third primary portion 131 and a third secondary portion 132. Referring to Figures 1a to 1d. For reasons similar to the reasons for fixing the first fin 211 (or the first connecting member) to the heat exchanger tubes 110, 120, the second fin 212 (or the second connecting member, such as the second auxiliary heat transfer surface) is fixed to the second primary portion 121 and to the third primary portion 131. In addition, at least a portion of the first secondary portion 112, at least a portion of the second secondary portion 122, and at least a portion of the third secondary portion 132 extend linearly in parallel within an imaginary plane P. In an embodiment, at least the portion of the first secondary portion 112, at least the portion of the second secondary portion 122, and at least the portion of the third secondary portion 132 extend linearly in parallel so that the central axes of these portions belong to the plane P.

[0075] In this embodiment, the wall 200 includes a second gap 222. The second gap 222 is arranged between the second secondary portion 122 and the third secondary portion 132 (see Figures 1b and 1d). In addition, the wall 200 is configured so that at least a portion of the second gap 222 penetrates the plane P. In addition, the granular material can be spread (i.e., can be spread) from the first side S1 of the plane P to the opposite second side S2 of the plane P (as described above) through the first gap 221, and the granular material can return (i.e., can return) from the second side S2 of the plane P to the first side S1 of the plane P through the second gap 222. For example, the granular material can reach the second gap 222 from the first gap 221, bypassing the second secondary portion 122 on the side of the second side S2 of the plane P. This spreading of the granular material is shown by the arrow AR2 in Figure 1d. Naturally, this feature is not a feature related to the granular material itself, which is arranged in the furnace 310 in use. In other words, in this embodiment, the wall 200 does not have such a portion: this portion will prevent the granular material from

[0076] from a first side S1 of the plane P through at least a portion of the first gap 221 and across the plane P to an opposite second side S2 of the plane P, and

[0077] From the second side S2 of the plane P back to the first side S1 of the plane P through the second gap 222 .

[0078] Preferably, the wall also does not have a portion that prevents particulate material from bypassing the second secondary portion 122 from the first gap 221 to the second gap 222 on the second side S2 of the plane P. For example, if the wall 200 is used as a partition wall (see Figure 3a to Figure 3c ), the bed material can spread from the first side S1 to the second side S2 and from the second side S2 to the first side S1 through the gaps 221, 222. However, in use, the bed material does not immediately return to the first side, nor does it typically bypass the tube along the shortest possible route. Instead, the bed material may circulate on the second side S2 for a period of time before returning to the first side S1.

[0079] In this embodiment, since the particulate material can pass through the first gap 221 and return to the first side S1 through the second gap 222, the tendency to form eddies is reduced. Therefore, the particulate does not need to return through the same first gap 221 (which would form some eddies). It should also be noted that the bed material does not need to bypass the second secondary portion 122 on the second side S2 of the plane P near the second secondary portion 122. Instead, the bed material can circulate on the second side S2 for a period of time before returning to the first side S1, especially when the wall 200 is used as a dividing wall.

[0080] In this embodiment, a portion of the third secondary portion 132 extends from the refractory material 230 to the first direction Dir1, and the second gap 222 extends from the refractory material 230 to the first direction Dir1. In addition, for the reasons detailed above, preferably, the outer diameter d32 of the third secondary portion 132 is less than or equal to the outer diameter d31 of the third primary portion 131.

[0081] The wall 200 of Figures 1a to 1d is shown in Figures 2a to 2d as being free of refractory material 230. Figures 2a to 2d also show some dimensional measurements of heat exchanger tubes 110, 120, 130. Referring to Figures 1a to 1d and Figures 2a to 2d, in one embodiment, the first secondary portion 112 has a first profile shape extending in the longitudinal direction of the first secondary portion 112, so that the first profile shape has a constant outer diameter d12 over the entire length of the first secondary portion 112, and the length of the first secondary portion 112 is greater than zero. In this embodiment, this is particularly applicable to the body of the first secondary portion 112. This has the following benefits: the first secondary portion 112 of the first heat exchanger tube 110 can be manufactured by using a tube having an outer diameter smaller than the first primary portion 111 of the first heat exchanger tube 110. The first secondary portion 112 can, for example, be welded to the first primary portion 111. Another suitable manufacturing technique for forming the first secondary portion 112 is to lathe a tube having a reasonably thick wall to reduce the outer diameter of the first secondary portion 112. However, it is often more economically feasible to connect two tubes having different outer diameters.

[0082] When manufacturing the heat exchanger tube by connecting different types of tubes to form the parts 111, 112, it is preferred that the inner diameter d of the first secondary part 112 is i 12 is smaller than the inner diameter d of the first primary part 111 i 11, and the inner diameter d of the second secondary portion 122 i 22 is smaller than the inner diameter d of the second primary part 121 i 21. This has the effect that, on the one hand, the primary parts 111, 121 present less flow resistance because of their larger inner diameter, while on the other hand, all parts of the tube 111, 112, 121, 122 can have sufficient, but not excessive, pressure and temperature resistance.

[0083] For similar reasons, in this embodiment, the second secondary portion 122 has a second profile shape extending in the longitudinal direction of the second secondary portion 122, so that the second profile shape has a constant outer diameter d22 over the entire length of the second secondary portion 122, and the length of the second secondary portion is greater than zero. In this embodiment, this applies in particular to the body of the second secondary portion 122.

[0084] In one embodiment, the secondary parts 112, 122 are provided with coatings 119, 129. In one embodiment, the body of the first secondary part 112 (i.e., the first secondary part 112 without the coating 119) has a first contour shape extending in the longitudinal direction of the first secondary part 112, so that the first contour shape has a constant outer diameter d12 over the entire length of the first secondary part 112. In one embodiment, the body of the second secondary part 122 (i.e., the second secondary part 122 without the coating 129) has a second contour shape extending in the longitudinal direction of the second secondary part 122, so that the second contour shape has a constant outer diameter d22 over the entire length of the second secondary part 122.

[0085] In this case, it is preferred that only a portion of the first secondary portion 112 is covered by the refractory material 230, and only a portion of the second secondary portion 122 is covered by the refractory material 230. In this case, a portion of the first secondary portion 112 (which may have a constant outer diameter) defines the first gap 221, and a portion of the second secondary portion 122 (which may have a constant outer diameter) defines the first gap 221. In this case, the first gap 221 is reasonably large to allow the granular material to enter the second side S2 from the first side S1, which ensures the diffusion of the vortex and / or the spreading of the bed material from the first side to the second side and its return, as described above.

[0086] In one embodiment, the first primary part 111 has a third profile shape extending in the longitudinal direction of the first primary part 111, so that the third profile shape has a constant outer diameter d11 over the entire length of the first primary part 111, and the length of the first primary part 111 is greater than zero. In a similar manner, in one embodiment, the second primary part 121 has a fourth profile shape extending in the longitudinal direction of the second primary part 121, so that the fourth profile shape has a constant outer diameter d21 over the entire length of the second primary part 121, and the length of the second primary part is greater than zero.

[0087] In addition, the first secondary portion 112 does not need to be directly connected to the first primary portion 111. Therefore, in one embodiment, the first heat exchanger tube 110 includes a first primary connection portion 114 connecting the first primary portion 111 to the first secondary portion 112; and the second heat exchanger tube 120 includes a second primary connection portion 124 connecting the second primary portion 121 to the second secondary portion 122. Refer to Figures 1a, 1b, 2a and 2b.

[0088] The corrosion resistance or maintainability of the (first, second, third) secondary parts 112, 122, 132 can be further improved by using a coating (119, 129, 139). Such a coating 119, 129, 139 is Figures 4a to 4d and Figure 2e . The coating preferably comprises a corrosion-resistant metal or ceramic. However, the coating may comprise a sacrificial metal, which need not be corrosion-resistant. The coating 119, 129, 139 may be in the form of a tube into which the secondary portion 112, 122, 132 (body) is pushed when the heat exchanger tubes 110, 120, 130 are manufactured. In an alternative, the coating may be sprayed onto the body of the secondary portion 112, 122, 132. As another alternative, in the case where the coating comprises a metal, the coating may be welded to the body of the secondary portion 112, 122, 132. Preferably, the coating 119, 129, 139 is an overlay welding comprising a suitable alloy. The coating 119, 129, 139 may form a portion of the secondary portion 112, 122, 132. It has been noted that a weld overlay of a material having at least 20% Cr and a low Fe content on the surface exposed to the furnace gases significantly reduces wall erosion. An example of a suitable alloy includes alloy 625 (Ni-22Cr-9Mo-3.5Nb). However, this coating does not need to be extremely wear resistant, since the technical function of the coating is to serve as a sacrificial layer. Thus, if necessary, the wall 200 can be maintained by adding more sacrificial material after a period of use, without having to replace the tube itself.

[0089] The coating 119, 129 can be machined, for example, turned after being welded to the secondary part 112, 122, 132. As an example, a tube intended to be used as a secondary part can first be covered with a coating (e.g., welded). Thereafter, in particular if the coating has a variable thickness, the tube can be turned to smooth out the variation in coating thickness. This ensures that the secondary part does not include protrusions that will cause further eddy currents to be generated. In addition, this can help reduce the difference between the outer diameters of the primary part 111, 121 and the secondary part 112, 122.

[0090] If a coating 119, 129, 139 is used, the coating is preferably arranged at a position where the particulate material has a tendency to spread in the normal direction of the wall 200. Furthermore, it is the refractory material 230 that causes the tendency of the particulate material to spread in the normal direction of the wall 200. Therefore, the coating 119, 129 is arranged so that the coating 119, 129 defines a first gap 221 and extends from the refractory material 230. That is, in the longitudinal direction of the heat exchanger tube, the uncovered portion of the heat exchanger tube is not arranged between the refractory material and the covered portion of the heat exchanger tube.

[0091] Thus, in one embodiment, the wall 200 includes a first coating 119 disposed on at least a portion of the first secondary portion 112 and a second coating 129 disposed on at least a portion of the second secondary portion 122. Figure 4a 4 b . Thus, the first coating 119 forms part of the surface of the first secondary portion 112 ; and the second coating 129 forms part of the surface of the second secondary portion 122 .

[0092] At least a portion of the first coating 119 extends from the refractory material 230 in the first direction Dir1 on the first secondary portion 112 and completely surrounds at least a portion of the first secondary portion 112 laterally. Therefore, at least a portion of the first coating 119 defines a first gap 221. Figure 4a As shown, the first coating 119 does not need to be in the longitudinal direction ( Figure 4a The first coating 119 covers the entire first secondary portion 112. However, as described above, the first coating 119 completely surrounds at least a portion of the first secondary portion 112 laterally.

[0093] In a similar manner, at least a portion of the second coating 129 extends from the refractory material 230 on the second secondary portion 122 in the first direction Dir1 and laterally completely surrounds at least a portion of the second secondary portion 122 .

[0094] In this manner, at least a portion of the first coating 119 defines the first gap 221, and at least a portion of the second coating 129 defines the first gap 221. Figure 4a As shown, the first gap may also be defined by the uncovered portions of the first secondary portion 112 and the second secondary portion 122 .

[0095] Consistent with the above, the first coating layer 119 includes metal or ceramic, and the second coating layer 129 includes metal or ceramic. The materials disclosed above, such as alloys, are usable.

[0096] Reference Figure 4d Preferably, the first coating 119 extends along the first direction Dir1 to the first primary connecting part 114 (if present) or to the first primary part 111. In a similar manner, preferably, the second coating 129 extends along the first direction Dir1 to the second primary connecting part 124 (if present) or to the second primary part 121. In this case, the coatings 119, 129 protect the rest of the secondary parts 112, 122.

[0097] However, near the primary part 111, 121, the bed material tends to fall downwards along the primary part 111, 121. In this way, the bed material has a tendency to continue spreading in the same direction (i.e., opposite to the first direction Dir1) also below the primary part 111, 121. This tendency forms a curtain along which the bed material usually falls at least a distance (but not necessarily) until the surface of the refractory material 230. The area of ​​the secondary part 112, 122 that remains between the curtain and the imaginary plane P is not exposed to high erosion.

[0098] As mentioned above, the secondary part 112, 122 does not protrude from the curtain defined by the outer surface of the primary part 111, 121. In particular, in an embodiment, the secondary part 112, 122 is coaxial with the primary part 111, 121 and has a smaller outer diameter, whereby the upper part of the secondary part 112, 122 is arranged in the shadow of the primary part 111, 121 (i.e., between the imaginary plane P and the curtain). Therefore, the upper part of the secondary part 112, 122 does not need to include a coating (see Figure 4c ). However, since the refractory material 230 directs the bed material towards the plane P, it is preferred to use the coatings 119, 129; and they extend a distance from the refractory material 230 in the first direction Dir1.

[0099] Preferably, the wall 200 includes the third heat exchanger tube 130 as described above. Furthermore, in this case, at least a portion of the second coating 129 also defines a second gap 222. In an embodiment, the wall 200 includes a third coating 139 arranged on at least a portion of the third secondary portion 132. At least a portion of the third coating 139 defines a second gap 222 in a similar manner as detailed above for the other coatings 119, 129.

[0100] To ensure that even if the refractory material 230 is worn, the uncovered portion is not exposed to erosion, it is preferred that the coating 119, 129, 139 also extends into the refractory material, ie, the coating extends from the interface of the refractory material to the opposite direction - Dir1 to the first direction.

[0101] In this case and in a preferred embodiment, a portion of the first coating 119 is disposed laterally between the first secondary portion 112 and the refractory material 230. More specifically, and considering that the first coating 119 forms a portion of the first secondary portion 112, a portion of the first coating 119 is disposed laterally between the inner surface of the first secondary portion 112 and the refractory material 230. In a similar manner, a portion of the second coating 129 is disposed laterally between the second secondary portion 122 and the refractory material 230. More specifically, and considering that the second coating 129 forms a portion of the second secondary portion 122, a portion of the second coating 129 is disposed laterally between the inner surface of the second secondary portion 122 and the refractory material 230. Referring to Figure 4a and Figure 4b.

[0102] Preferably, the first coating 119 comprises a metal alloy and is a cladding, and the second coating 129 comprises a metal alloy and is a cladding. Preferably, the thickness of the first coating 119 is 1 mm to 4 mm, more preferably 2 mm to 3 mm. Preferably, the thickness of the second coating 129 is 1 mm to 4 mm, more preferably 2 mm to 3 mm.

[0103] Particularly preferably, the wall 200 is used as a partition wall of a furnace of a fluidized bed boiler, such as a circulating fluidized bed boiler ( Figure 3a to Figure 3c ), and the secondary parts 112, 122, 132 are provided with coatings 119, 129, 139. In addition, when the wall 200 is used as a partition wall, it is preferred that the refractory material 230 is arranged between two planes Pa and Pb parallel to the plane P defined above, as shown in Figure 4b. Preferably, in this embodiment, the refractory material 230 is arranged between a first plane Pa and a second plane Pb parallel to the imaginary plane P, wherein at least a portion of the first secondary part 112 and at least a portion of the second secondary part 122 extend in a straight line; and the wall 200 is configured so that the particulate material (i.e., the bed material) can be spread (i.e., the particulate material can be spread) from the first side S1 of the first plane Pa to the opposite second side S2 of the second plane Pb through the first gap 221. Such spreading of the bed material is shown by arrow AR3 in Figure 4b.

[0104] This has the benefit that the bed material, once spread from the first side S1 of the first plane Pa through the first gap 221 to the opposite second side S2 of the second plane Pb, can fall downwardly on this second side S2 , which further reduces the tendency for eddies to form near the refractory material 230 .

[0105] As discussed, the outer diameter of the secondary portion 112, 122, 132 may be substantially constant, and this outer diameter may include a coating 119, 129, 139, as detailed above. Figure 4aand Figure 4b. As shown in the figure, in the longitudinal direction ( Figure 4a In Sz), the outer diameter of the secondary parts 112, 122, 132 is constant only when the secondary parts 112, 122, 132 are provided with the coating 119, 129, 139, respectively. However, when the coating is terminated, the outer diameter decreases by twice the thickness of the coating 112, 129, 139. According to these definitions, in Figure 4a In the embodiment of the invention, the first primary connecting portion 114 connecting the first primary portion 111 to the first secondary portion 112 comprises a tapered portion and a portion having a constant outer diameter, which is equal to the uncovered portion of the first secondary portion 112. This also applies mutatis mutandis to Figure 4a A second primary connecting portion 124 and a second secondary portion 122 are shown.

[0106] In one embodiment (which will be discussed in detail), the wall 200 is substantially flat and extends downward to the support structure. In this case, the refractory material 230 can extend downward to the grate or support structure. Referring to Figures 1a and 1b, the heat exchanger tubes can include a tertiary section (113, 123, 133) that is wider than the secondary section (112, 122, 132). However, this is not mandatory. Instead, the secondary section (112, 122, 132) can extend the entire desired length within the refractory material and have only an outer diameter d12, d22, d32. Referring to Figure 4a It is possible that only a portion of each of the heat exchanger tubes 110, 120, 130 extending within the refractory material 230 is covered by the coating 119, 129, 139. Therefore, the outer diameter of the heat exchanger tubes extending within the refractory material 230 can even be reduced downward. However, referring to Figure 4c , when the heat exchanger tubes 110, 120, 130 are provided with the coating 119, 129, 139, it is preferred that the heat exchanger tubes 110, 120, 130 include a tertiary portion 113, 123, 133 that is wider than the secondary portion (112, 122, 132). In this case, the first secondary connecting portion 115 may connect the first secondary portion 112 to the first tertiary portion 113. What has been said about the outer diameter of the first secondary portion 112 and the extension of the first primary connecting portion 114 also applies mutatis mutandis to the first secondary connecting portion 115.

[0107] Preferably and with reference to Figures 1a, 1b, Figure 4c and Figure 4d, the first heat exchanger tube 110 includes a first tertiary portion 113, and the second heat exchanger tube 120 includes a second tertiary portion 123. The first secondary portion 112 is arranged between the first primary portion 111 and the first tertiary portion 113 (in the longitudinal direction of the first heat exchanger tube 110). The second secondary portion 122 is arranged between the second primary portion 121 and the second tertiary portion 123 (in the longitudinal direction of the second heat exchanger tube 120). In order to reduce the flow resistance generated by the first heat exchanger tube 110 and the second heat exchanger tube 120, the inner diameter d of the first tertiary portion 113 is i 13 is equal to the inner diameter d of the first primary part 111 i 11, and the inner diameter d of the second tertiary portion 123 i 23 is equal to the inner diameter d of the second primary part 121 i 21. It is also preferred that the inner diameter d of the first tertiary portion 113 is i 13 is larger than the inner diameter d of the first secondary portion 112 i 12, and the inner diameter d of the second tertiary portion 123 i 23 is larger than the inner diameter d of the second secondary portion 122 i twenty two.

[0108] For manufacturing reasons, it is preferred that the tertiary parts 113, 123 are similar to the primary parts 111, 121. Therefore, it is also preferred that the outer diameter d13 of the first tertiary part 113 is equal to the outer diameter d11 of the first primary part 111 and the outer diameter d23 of the second tertiary part 123 is equal to the outer diameter d21 of the second primary part 121.

[0109] To protect the tertiary portions 113 , 123 from corrosion, in one embodiment, at least a portion of the first tertiary portion 113 is covered by a refractory material 230 , and at least a portion of the second tertiary portion 123 is covered by a refractory material 230 .

[0110] Any of the embodiments of the wall 200 described in detail above can be used in particular as a wall of the fluidized bed boiler 300. The fluidized bed boiler 300 is Figure 3a to Figure 3c , Figure 5a as well as Figure 7a 7b. The fluidized bed boiler 300 shown in the figure is of the circulating type. Any embodiment of the wall 200 described in detail above can be used as the wall of the bubbling fluidized bed boiler 300.

[0111] Therefore, the fluidized bed boiler 300 includes: a furnace 310; an air nozzle 330 for allowing combustion air to enter the furnace 310; and a fuel inlet 340 for allowing fuel to enter the furnace 310. Figure 3a to Figure 3c , Figure 5a as well as Figure 7aand Figure 7b. If the fluidized bed boiler is a circulating fluidized boiler, it includes a particle separator 320 for separating particulate material from the flow received from the furnace 310 so that at least some of the separated particulate material is returned to the furnace 310. In a circulating fluidized bed boiler, the air nozzles 330 are operated so that a certain amount of air is supplied to the furnace 310 so that the mixture of bed material, fuel, ash, air and flue gas mainly travels upward in the furnace 310 and is further dispersed to the particle separator 320. The particle separator 320 preferably includes a cyclone separator for separating at least most of the solid materials from the mixture and returning them to the furnace 310. The flue gas (i.e. the remaining part of the mixture) is discharged to the flue gas channel 322. The fluidized bed boiler 300 is also provided with a heat exchanger 324 for recovering heat from the furnace 310 and / or from the flue gas. As an example, Figure 3a A heat exchanger 324 arranged in the flue gas channel 322 is shown.

[0112] The fluidized bed boiler 300 further comprises at least one wall 200 according to any of the embodiments of the wall 200 as detailed above. As detailed in the background, even if most of the material flows upwards in the furnace 310, near the walls 200 of the furnace the material flow may be substantially downwards.

[0113] In one embodiment, wall 200 is a dividing wall that divides furnace 310 into two sections, and the two sections function in a substantially similar manner, such as Figure 3a to Figure 3c as well as Figure 7a In one embodiment, the wall 200 is a side wall of the furnace 310, such as Figure 5a 5c. In one embodiment, the fluidized bed boiler 300 comprises a first wall according to any embodiment of the wall 200 as detailed above and a second wall (not shown) according to any embodiment of the wall 200 as detailed above. In one embodiment, the first wall is a partition wall of the furnace and the second wall is a side wall of the furnace. In one embodiment, the first wall is a partition wall of the furnace and the second wall is another partition wall of the furnace. In one embodiment, the first wall is a side wall of the furnace and the second wall is a side wall of the furnace.

[0114] In the following, the wall 200 refers to the (only) wall, the first wall, the second wall or both the first wall and the second wall of the type disclosed above.

[0115] In the circulating fluidized bed boiler 300, the wall 200 defines the furnace 310 so that at least the first side S1 of the plane P is exposed to a portion of the furnace 310. In other words, a portion of the furnace 310 is arranged on the first side S1 of the plane. In addition, in this embodiment, at least a portion of the refractory material 230 is arranged on the first side S1 of the plane P. When arranged in this way, the gaps 221, 222 as detailed above function in the above-described manner. In addition, the wall is arranged so that the first direction Dir1 forms an angle of up to 30 degrees with the upward vertical direction Sz. In this way, in this embodiment, the first direction Dir1 is more or less vertical upward, as described above. The angle also ensures that the gaps 221, 222 function as desired; and the secondary parts 112, 122 of the heat exchanger tubes 110, 120 have the technical effect as detailed above, and the outer diameter of the secondary part is smaller than the outer diameter of the primary part 111, 121.

[0116] Preferably, the wall 200 is a dividing wall of the furnace 310. In this case, on both sides of the wall 200, the bed material has a tendency to flow down along the wall until it hits the refractory material 230 (or the bed material accumulated thereon). And, at this time, the bed material is guided in transverse directions, one of which is towards the wall 200. Therefore, in this case, the gaps 221, 222 provide a passage for bed material and gas from either side of the wall 200 to the opposite side of the wall 200. In this way, it has been found that the wall 200 is particularly effective as a dividing wall of the fluidized bed boiler 300. Therefore, in one embodiment, the first part P1 of the furnace 310 is arranged on a first side of the wall 200, and the second part P2 of the furnace 310 is arranged on the opposite second side of the wall 200. In other words, in one embodiment, the first part P1 of the furnace 310 is arranged on a first side of an imaginary plane P defined by the wall, and the second part P2 of the furnace 310 is arranged on the opposite second side of the imaginary plane P. Thus, the second side S2 of the plane P is exposed to the second part P2 of the furnace 310. See Figures 3b and 3c. Also in Figure 7b, the plane P divides the furnace into two parts. Furthermore, in order to divide the furnace 310 into these two parts (P1, P2) so that they function in a substantially similar manner, the first part P1 of the furnace 310 is provided with a first set 330A of air nozzles 330 for fluidizing the bed material in the first part P1 of the furnace 310, and the second part P2 of the furnace 310 is provided with a second set 330B of air nozzles 300 for fluidizing the bed material in the second part P2 of the furnace 310 (see Figure 3c). In this embodiment, preferably, the first and second primary portions (111, 121) and the first and second secondary portions (112, 122) of the heat exchanger tubes (110, 120) of the wall 200 extend in a plane P. Therefore, there are no bending points between the primary portions (111, 121) and the secondary portions (112, 122), which also ensures that both sides of the wall 200 function in a substantially identical manner.

[0117] Particularly in large fluidized bed boilers, there is a problem of supporting the loads. The loads are caused on the one hand by the components of the boiler itself and on the other hand by the granular material arranged in the furnace 310. In particular, typically the air nozzles 330 are arranged to a grate 370, which supports the loads of the granular material. Therefore, the grate 370 itself needs to be properly supported. Although the side walls of the furnace can support some of the loads, preferably at least the partition walls, which are the walls 200 according to the embodiments disclosed above, support the loads. This has the following benefits: the partition walls can be essentially flat, whereby the heat exchanger tubes of the wall 200 can be straight and essentially vertical. Essentially vertical straight tubes bear loads to a much greater extent than, for example, curved tubes or non-vertical tubes. It should also be noted that typically the side walls of the furnace are curved in such a way that their load-bearing capacity is reduced. For curved tubes refer to Figure 5a To Figure 5c. Figure 3a to Figure 3c , Figure 7a 7 b , when the wall 200 is used as a supporting partition wall of the furnace 310 , the wall 200 may be suspended from a suspension structure 350 , and the wall 200 may support a support structure 360 ​​that supports a grate 370 .

[0118] For these reasons, refer to Figure 3a to Figure 3c , Figure 7a 7b, a preferred embodiment of the circulating fluidized bed boiler includes: a suspension structure 350 including an upper beam; a support structure 360 ​​including a lower beam; and a grate 370 arranged above the support structure 360. In addition, in this embodiment, the wall 200 includes straight heat exchanger tubes, and the wall 200 is configured to support the support structure 360. The grate 370 includes air nozzles 330. When the fluidized bed boiler 300 includes multiple groups of air nozzles, the grate 370 includes a first group of air nozzles 330A and a second group of air nozzles 330B.

[0119] More specifically, in this embodiment, the first heat exchanger tube 110 and the second heat exchanger tube 120 of the wall 200 extend straight between the suspension structure 350 and the support structure 360; and the first direction Dir1 forms an angle of at most 5 degrees with the upward vertical direction Sz. As described above, these features improve the load bearing capacity of the wall 200.

[0120] Furthermore, to utilize the load bearing capacity of the wall, the wall 200 is secured to (eg, suspended from) a suspension structure 350 , the wall 200 supports (eg, secured to) a support structure 360 ​​, and the support structure 360 ​​supports a grate 370 .

[0121] In one embodiment, the lower portion of the furnace 310 has a downwardly tapered shape, while the upper portion of the furnace may have a substantially constant cross-section. The upper portion may be defined, for example, such that the upper portion is arranged above a partition plane DP defined by: [A] a bending line BL and a vertical normal of a side wall of the furnace 310; or [B] a bending line BL of opposite side walls of the furnace 310. Figure 3c , Figure 5a and Figure 5b.

[0122] Therefore, in one embodiment, two opposite side walls of the furnace 310 are provided with bending lines BL, such as Figure 3c and Figure 5a As shown. Figure 3c and Figure 5a In the figure, these bending lines BL extend in a direction Sx perpendicular to the plane of the figure. Such bending lines BL of the side wall define a separation plane DP. Therefore, the bending lines BL are arranged on the separation plane DP. The separation plane DP is not a real thing, but a plane defined in the field of geometry, in which sense the separation plane DP is imaginary. Above the separation plane DP, the primary part 311 of the furnace 310 is arranged. Below the separation plane DP, the secondary part 312 of the furnace 310 is arranged. In an embodiment, only one side wall of the furnace 310 is provided with a bending line BL, which defines the separation plane DP (whose normal is vertical). If two bending lines BL define the separation plane DP, the normal of the separation plane DP does not need to be vertical.

[0123] Due to the at least one bending line BL, the secondary part 312 of the furnace 310 has a downwardly tapered shape. The primary part 311 of the furnace 310 may have a shape having a constant cross section in the vertical direction, the cross section having a normal line in the vertical direction. The secondary part 312 extends downward to the grate 370. The secondary part 312 extends upward to the primary part 311. Figure 3c and Figure 5a In FIG. 3 , the partition plane DP forms an interface between the primary part 311 and the secondary part 312 . The primary part 311 extends upward from the secondary part 312 .

[0124] Due to the downwardly tapering shape of the secondary part 312 of the furnace 310, the bed material flow is reasonably turbulent in the secondary part 312. In addition, turbulence has a tendency to erode surfaces. In order to prevent erosion of the heat exchanger tubes 110, 120, 130 in the secondary part 312 of the furnace 310, in one embodiment, in the secondary part 312 of the furnace, the heat exchanger tubes 110, 120, 130 of the wall 200 are covered with a refractory material 230. More preferably, the refractory material 230 is provided on the heat exchanger tubes 110, 120, 130 of the wall 200 that penetrates the secondary part 312 of the furnace 310. Therefore, in one embodiment, the first gap 221 and the second gap 222 of the wall 200 are arranged in the primary part 311 of the furnace 310.

[0125] In particular, in one embodiment, the first gap 221 is arranged in the primary part 311 of the furnace. In one embodiment, the first gap 221 is arranged above a partition plane DP defined by one or more bending lines BL of the side wall of the furnace. In one embodiment, a second imaginary plane IP (whose normal is vertical) intersects the first gap 221 and is arranged at a higher vertical level than (i) the bending line BL of the side wall of the furnace 310, or (ii) one of the multiple bending lines BL of the side wall of the furnace 310, or (iii) all the bending lines BL of the side wall of the furnace 310, which define the secondary part 312 of the furnace 310. The second imaginary plane IP is imaginary in the sense that it is not a real thing but a plane defined in the field of geometry. This also applies to the second gap 222 after necessary modifications.

[0126] Reference Figure 5a To Figure 5c, any embodiment of the wall 200 can be used as a side wall of the furnace 310 of the fluidized bed boiler 300. In such an embodiment, the first part P1 of the furnace 310 is arranged on a first side of the wall 200, and the second part P2 of the furnace 310 is arranged on an opposite second side of the wall 200, whereby the second side S2 of the plane P is exposed to the second part P2 of the furnace 310. Therefore, the first part P1 of the furnace 310 is arranged on a first side of the wall 200, and the second part P2 of the furnace 310 is arranged on an opposite second side of the wall 200. However, when the wall 200 is a side wall, the functions of the parts P1 and P2 of the furnace 310 are different. In this case, most of the combustion occurs in the first part P1, while the second part P2 is mainly used to prevent the formation of vortices as described above. Therefore, with reference to Figure 5a In one embodiment, the first portion P1 of the furnace 310 is provided with air nozzles 330 for fluidizing the bed material in the first portion P1 of the furnace 310. However, the second portion P2 of the furnace 310 has no air nozzles.

[0127] Furthermore, in order to prevent bed materials from escaping from the furnace 310 , the fluidized bed boiler 300 includes a plate 250 . At least a portion of the plate 250 is disposed on the second side S2 of the plane P. The plate 250 is fixed to the first fin 211 and is configured to prevent bed materials from escaping from the furnace 310 .

[0128] Figure 7a FIG. 7 b shows another embodiment of the wall 200. As shown in FIG. 7 b, when viewed from above (see Figure 7a , cross section VIIb), the wall 200 has a cross shape. Therefore, the wall 200 includes a first portion 200a and a second portion 200b. The first portion 200a and the second portion 200b are planar and arranged perpendicular to each other. As described above, the first portion 200a includes heat exchanger tubes 110, 120, 130 and multiple portions 111, 112, 121, 122, 131, 132 thereof. The secondary portions 112, 122 of these tubes define an imaginary plane P, as discussed above and shown in FIG. 7b. As detailed above, such a wall 200 can be used as a partition wall. The effect of the wall 200 is twofold. First, having a vertical portion can increase the support capacity of the wall 200. As described above, the wall 200 can support, for example, a grate 370. Secondly, having a vertical portion can increase the area of ​​the heat transfer surface and improve heat recovery in this way. However, heat recovery can also be improved by using many heat exchanger tubes (e.g., wide wall 200).

[0129] Referring to FIG8a, FIG8b, FIG8c, Figure 8f 8g, heat recovery can also be improved by using auxiliary heat transfer surfaces. Figures 8a to 8c show an embodiment of the wall 200. In this embodiment, the wall 200 includes auxiliary heat transfer surfaces 241, 242 in its upper part. For example, the first primary part 111, the second primary part 121 and the first fin 211 that form a part of the wall 200 can constitute a plane part. The first auxiliary heat transfer surface 241 can protrude from the plane part, as shown in Figures 8a to 8c. In a similar manner, the second auxiliary heat transfer surface 242 can protrude from the plane defined by the first primary part 111, the second primary part 121 and the first fin 211, as shown in Figures 8a to 8c. Such auxiliary heat transfer surfaces 241, 242 can be called wings. As shown in Figure 8c, the second auxiliary heat transfer surface 242 can, for example, include a heat transfer pipe for recovering heat. This also applies to other auxiliary heat transfer surfaces (such as 241). The purpose of the auxiliary heat transfer surfaces 241, 242 is to improve heat recovery.

[0130] Reference Figure 8d and Figure 8e , for example, walls with auxiliary heat transfer surfaces 241 , 242 may be used near the side walls of the furnace 310 to improve heat recovery.

[0131] As shown in FIGS. 8a to 8c , when the wall includes auxiliary heat transfer surfaces 241, 242, such auxiliary heat transfer surfaces 241, 242 may penetrate the fins 211, 212. Figure 8f As shown in Figure 8g, the auxiliary heat transfer surfaces 241, 242 can form a connector connecting the primary sections 111, 121 of the tubes 110, 120. Therefore, the fins (211, 212) and the auxiliary heat transfer surfaces (241, 242) can both be considered as connectors connecting adjacent primary sections of the heat exchanger tubes.

[0132] Auxiliary heat transfer surfaces (if used) need not be arranged to connect every pair of adjacent heat exchanger tubes. On the contrary, as an example, even if the second primary part 121 is connected to the third primary part 131 by fins (as shown in Figure 1c), the first primary part 111 can be connected to the second primary part 121 by auxiliary heat transfer surfaces 241 (as shown in Figure 8g). A sufficient distance between the auxiliary heat transfer surfaces 241, 242 can improve the heat transfer from the bed material. A sufficient distance between the auxiliary heat transfer surfaces 241, 242 can be achieved by using an appropriate number of heat exchanger tubes connected with fins between the auxiliary heat transfer surfaces 241, 242.

Claims

1. A wall (200) for a fluidized bed boiler (300), characterized in that: The wall (200) comprises: A first heat exchanger tube (110) comprising a first primary portion (111) and a first secondary portion (112), a second heat exchanger tube (120) arranged in parallel with the first heat exchanger tube (110), the second heat exchanger tube (120) comprising a second primary portion (121) and a second secondary portion (122), a first connecting member (211, 241) fixed to the first primary part (111) and to the second primary part (121), and A first gap (221) is located between the first secondary portion (112) and the second secondary portion (122), wherein At least a portion of the first secondary portion (112) and at least a portion of the second secondary portion (122) extend linearly and in parallel within an imaginary plane (P), and At least a portion of the first gap (221) penetrates the plane (P) so that particulate material can be dispersed from a first side (S1) of the plane (P) to an opposite second side (S2) of the plane (P) through the first gap (221), and the wall (200) comprises: A refractory material (230) is arranged on at least one side of a portion of the first secondary portion (112) and a portion of the second secondary portion (122), such that A portion of the first secondary portion (112) extends from the refractory material (230) in a first direction (Dir1), A portion of the second secondary portion (122) extends from the refractory material (230) toward the first direction (Dir1), and The first gap (221) extends from the refractory material (230) toward the first direction (Dir1); wherein The outer diameter (d12) of the first secondary part (112) is smaller than or equal to the outer diameter (d11) of the first primary part (111), The outer diameter (d22) of the second secondary portion (122) is smaller than or equal to the outer diameter (d21) of the second primary portion (121), and The first direction (Dir1) forms an angle of at most 30 degrees with the upward vertical direction (Sz).

2. The wall (200) according to claim 1, characterized in that include: a third heat exchanger tube (130), arranged in parallel with the second heat exchanger tube (120), the third heat exchanger tube (130) comprising a third primary portion (131) and a third secondary portion (132), a second connecting member (212, 242) fixed to the second primary part (121) and to the third primary part (131), and A second gap (222) is located between the second secondary portion (122) and the third secondary portion (132), wherein At least a portion of the first secondary portion (112), at least a portion of the second secondary portion (122), and at least a portion of the third secondary portion (132) extend linearly and in parallel within the plane (P), and At least a portion of the second gap (222) penetrates the plane (P) so that particulate material can be dispersed from a first side (S1) of the plane (P) to an opposite second side (S2) of the plane (P) through the first gap (221), and returned from the second side (S2) of the plane (P) to the first side (S1) of the plane (P) through the second gap (222), wherein A portion of the third secondary portion (132) extends from the refractory material (230) toward the first direction (Dir1), and The second gap (222) extends from the refractory material (230) toward the first direction (Dir1).

3. The wall (200) according to claim 2, characterized in that The wall (200) is configured to enable particulate material to pass from the first gap (221) around the second secondary portion (122) to the second gap (222) on the side of the second side (S2) of the plane (P).

4. The wall (200) according to claim 3, characterized in that The outer diameter (d32) of the third secondary portion (132) is smaller than or equal to the outer diameter (d31) of the third primary portion (131).

5. The wall (200) according to any one of claims 1 to 4, characterized in that The body of the first secondary portion (112) has a first contour shape extending in the longitudinal direction of the first secondary portion (112), so that the first contour shape has a constant outer diameter (d12) over the entire length of the first secondary portion (112), the length of the first secondary portion (112) being greater than zero, The body of the second secondary portion (122) has a second profile shape extending in the longitudinal direction of the second secondary portion (122), so that the second profile shape has a constant outer diameter (d22) over the entire length of the second secondary portion (122), the length of the second secondary portion being greater than zero, Only a portion of the first secondary portion (112) is covered by the refractory material (230), whereby a portion of the first secondary portion (112) defines the first gap (221), and Only a portion of the second secondary portion (122) is covered by the refractory material (230), whereby a portion of the second secondary portion (122) defines the first gap (221).

6. The wall (200) according to any one of claims 1 to 4, characterized in that The first heat exchanger tube (110) includes a first primary connecting portion (114) connecting the first primary portion (111) to the first secondary portion (112), and The second heat exchanger tube (120) includes a second primary connecting portion (124) connecting the second primary portion (121) to the second secondary portion (122).

7. The wall (200) according to claim 2, characterized in that include: a first coating (119) disposed on at least a portion of the first secondary portion (112), and A second coating (129) is disposed on at least a portion of the second secondary portion (122) such that At least a portion of the first coating (119) extends from the refractory material (230) in the first direction (Dir1) on the first secondary portion (112) and laterally completely surrounds at least a portion of the first secondary portion (112), whereby at least a portion of the first coating (119) defines the first gap (221), and At least a portion of the second coating (129) extends from the refractory material (230) in the first direction (Dir1) on the second secondary portion (122) and completely surrounds at least a portion of the second secondary portion (122) laterally, whereby at least a portion of the second coating (129) defines the first gap (221), wherein The first coating (119) comprises metal or ceramic, and The second coating (129) includes metal or ceramic.

8. The wall (200) according to claim 7, characterized in that At least a portion of the second coating (129) defines the second gap (222).

9. The wall (200) according to claim 7, characterized in that A portion of the first coating (119) is disposed laterally between the body of the first secondary portion (112) and the refractory material (230), and A portion of the second coating (129) is disposed laterally between the body of the second secondary portion (122) and the refractory material (230).

10. The wall (200) according to claim 7, characterized in that The first coating (119) comprises a metal alloy and is a weld overlay, and the second coating (129) comprises a metal alloy and is a weld overlay.

11. The wall (200) according to claim 7, characterized in that The thickness of the first coating (119) is 1 mm to 4 mm, and The thickness of the second coating layer (129) is 1 mm to 4 mm.

12. The wall (200) according to claim 7, characterized in that The thickness of the first coating (119) is 2 mm to 3 mm, and The thickness of the second coating layer (129) is 2 mm to 3 mm.

13. The wall (200) according to any one of claims 1 to 4, characterized in that The first heat exchanger tube (110) comprises a first tertiary section (113), such that the first secondary section (112) is arranged between the first primary section (111) and the first tertiary section (113), wherein The inner diameter (d i 13) is larger than the inner diameter (d i 12), and The second heat exchanger tube (120) comprises a second tertiary section (123), such that the second secondary section (122) is arranged between the second primary section (121) and the second tertiary section (123), wherein The inner diameter (d i 23) is larger than the inner diameter (d i twenty two).

14. The wall (200) according to claim 13, characterized in that The first heat exchanger tube (110) comprises a first tertiary section (113), such that the first secondary section (112) is arranged between the first primary section (111) and the first tertiary section (113), wherein The inner diameter (d i 13) is equal to the inner diameter (d i 11), and The inner diameter (d i 23) is equal to the inner diameter (d i twenty one); The outer diameter (d13) of the first tertiary part (113) is equal to the outer diameter (d11) of the first primary part (111), and The outer diameter (d23) of the second tertiary part (123) is equal to the outer diameter (d21) of the second primary part (121); At least a portion of the first tertiary portion (113) is covered by the refractory material (230), and At least a portion of the second tertiary portion (123) is covered by the refractory material (230).

15. The wall (200) according to any one of claims 1 to 4, characterized in that The first secondary portion (112) is not provided with one or more fins, and The second secondary portion (122) is not provided with one or more fins.

16. A wall (200) according to any one of claims 1 to 4, characterized in that The first secondary portion (112) is coaxial with the first primary portion (111), and The second secondary part (122) is coaxial with the second primary part (121).

17. A fluidized bed boiler (300), characterized in that: include: Furnace (310), an air nozzle (330) for admitting combustion air into the furnace (310), a fuel inlet (340) for admitting fuel into the furnace (310), and The wall (200) according to any one of claims 1 to 4, wherein The wall (200) defines the furnace (310) such that at least a first side (S1) of the plane (P) is exposed to a portion of the furnace (310).

18. The fluidized bed boiler (300) according to claim 17, characterized in that: The fluidized bed boiler (300) includes a particle separator (320) for separating particulate material from a stream received from the furnace (310) so that at least some of the separated particulate material is returned to the furnace (310).

19. The fluidized bed boiler (300) according to claim 17, characterized in that: A first portion (P1) of the furnace (310) is arranged on a first side of the wall (200), The second portion (P2) of the furnace (310) is arranged on a second, opposite side of the wall (200), The first part (P1) of the furnace (310) is provided with a first set (330A) of air nozzles (330) for fluidizing the bed material in the first part (P1) of the furnace (310), and The second portion (P2) of the furnace (310) is provided with a second set (330B) of air nozzles (330) for fluidizing the bed material in the second portion (P2) of the furnace (310).

20. The fluidized bed boiler (300) according to claim 19, characterized in that: include: The suspension structure (350) includes an upper beam, A support structure (360) includes a lower beam, and A grate (370) is arranged above the support structure (360), wherein The grate (370) includes the first group (330A) of air nozzles and the second group (330B) of air nozzles, The wall (200) is fixed to the suspension structure (350), The wall (200) supports the support structure (360), The support structure (360) supports the grate (370), The first heat exchanger tube (110) and the second heat exchanger tube (120) of the wall (200) extend straight between the suspension structure (350) and the support structure (360), and The first direction (Dir1) forms an angle of at most 5 degrees with the upward vertical direction (Sz).

21. The fluidized bed boiler (300) according to any one of claims 17 to 20, characterized in that: The furnace (310) comprises a primary part (311) of the furnace (310) and a secondary part (312) of the furnace (310), The secondary portion (312) of the furnace (310) has a downwardly tapering shape, The primary part (311) of the furnace (310) is arranged above the secondary part (312) of the furnace (310), and A first gap (221) is arranged in the primary part (311) of the furnace (310).

22. The fluidized bed boiler (300) according to claim 21, characterized in that: An imaginary dividing plane (DP) forms an interface between the primary part (311) of the furnace and the secondary part (312) of the furnace, and The side wall of the furnace (310) comprises a bending line (BL) arranged on the imaginary dividing plane (DP), the imaginary dividing plane (DP) having a vertical normal, or Two opposing side walls of the furnace (310) include bending lines (BL) arranged on the imaginary dividing plane (DP).

23. The fluidized bed boiler (300) according to any one of claims 17 to 20, characterized in that: The body of the first secondary portion (112) has a first contour shape extending in the longitudinal direction of the first secondary portion (112), so that the first contour shape has a constant outer diameter (d12) over the entire length of the first secondary portion (112), the length of the first secondary portion (112) being greater than zero, The body of the second secondary portion (122) has a second profile shape extending in the longitudinal direction of the second secondary portion (122), so that the second profile shape has a constant outer diameter (d22) over the entire length of the second secondary portion (122), the length of the second secondary portion being greater than zero, Only a portion of the first secondary portion (112) is covered by the refractory material (230), whereby a portion of the first secondary portion (112) defines the first gap (221), and Only a portion of the second secondary portion (122) is covered by the refractory material (230), whereby a portion of the second secondary portion (122) defines the first gap (221).

24. The fluidized bed boiler (300) according to claim 23, characterized in that: The first heat exchanger tube (110) includes a first primary connecting portion (114) connecting the first primary portion (111) to the first secondary portion (112), and The second heat exchanger tube (120) includes a second primary connecting portion (124) connecting the second primary portion (121) to the second secondary portion (122).

25. The fluidized bed boiler (300) according to claim 23, characterized in that: include: a first coating (119) disposed on at least a portion of the first secondary portion (112), and A second coating (129) is disposed on at least a portion of the second secondary portion (122) such that At least a portion of the first coating (119) extends from the refractory material (230) in the first direction (Dir1) on the first secondary portion (112) and laterally completely surrounds at least a portion of the first secondary portion (112), whereby at least a portion of the first coating (119) defines the first gap (221), and At least a portion of the second coating (129) extends from the refractory material (230) in the first direction (Dir1) on the second secondary portion (122) and completely surrounds at least a portion of the second secondary portion (122) laterally, whereby at least a portion of the second coating (129) defines the first gap (221), wherein The first coating (119) comprises metal or ceramic, and The second coating (129) includes metal or ceramic.

26. The fluidized bed boiler (300) according to claim 25, characterized in that: The wall (200) includes a third heat exchanger tube (130), whereby At least a portion of the second coating (129) defines a second gap (222).

27. The fluidized bed boiler (300) according to claim 25, characterized in that: A portion of the first coating (119) is disposed laterally between the body of the first secondary portion (112) and the refractory material (230), and A portion of the second coating (129) is disposed laterally between the body of the second secondary portion (122) and the refractory material (230).

28. The fluidized bed boiler (300) according to any one of claims 25 to 27, characterized in that: The first coating (119) comprises a metal alloy and is a weld overlay, and the second coating (129) comprises a metal alloy and is a weld overlay.

29. The fluidized bed boiler (300) according to any one of claims 25 to 27, characterized in that: The thickness of the first coating (119) is 1 mm to 4 mm, and The thickness of the second coating layer (129) is 1 mm to 4 mm.

30. The fluidized bed boiler (300) according to any one of claims 25 to 27, characterized in that: The thickness of the first coating (119) is 2 mm to 3 mm, and The thickness of the second coating layer (129) is 2 mm to 3 mm.

31. The fluidized bed boiler (300) according to any one of claims 25 to 27, characterized in that: The first heat exchanger tube (110) comprises a first tertiary section (113), such that the first secondary section (112) is arranged between the first primary section (111) and the first tertiary section (113), wherein The inner diameter (d i 13) is larger than the inner diameter (d i 12), and The second heat exchanger tube (120) comprises a second tertiary section (123), such that the second secondary section (122) is arranged between the second primary section (121) and the second tertiary section (123), wherein The inner diameter (d i 23) is larger than the inner diameter (d i twenty two).

32. The fluidized bed boiler (300) according to claim 31, characterized in that: The inner diameter (d i 13) is equal to the inner diameter (d i 11), and The inner diameter (d i 23) is equal to the inner diameter (d i twenty one); The outer diameter (d13) of the first tertiary part (113) is equal to the outer diameter (d11) of the first primary part (111), and The outer diameter (d23) of the second tertiary part (123) is equal to the outer diameter (d21) of the second primary part (121); At least a portion of the first tertiary portion (113) is covered by the refractory material (230), and At least a portion of the second tertiary portion (123) is covered by the refractory material (230).

33. The fluidized bed boiler (300) according to any one of claims 25 to 27, characterized in that: The first secondary portion (112) is not provided with one or more fins, and The second secondary portion (122) is not provided with one or more fins.

34. The fluidized bed boiler (300) according to claim 17 or 18, characterized in that: A first portion (P1) of the furnace (310) is arranged on a first side of the wall (200), a second portion (P2) of the furnace (310) being arranged on an opposite second side of the wall (200), whereby the second side (S2) of the plane (P) is exposed to the second portion (P2) of the furnace (310), The first part (P1) of the furnace (310) is provided with air nozzles for fluidizing the bed material in the first part of the furnace (310), and The second portion (P2) of the furnace (310) is free of air nozzles, and The fluidized bed boiler (300) comprises a plate (250), at least a portion of which is arranged on the second side (S2) of the plane (P), wherein The plate (250) is fixed to the first connection member (211, 241) and is configured to prevent bed material from escaping from the furnace (310).

35. The fluidized bed boiler (300) according to any one of claims 25 to 27, characterized in that: The first secondary portion (112) is coaxial with the first primary portion (111), and The second secondary part (122) is coaxial with the second primary part (121).

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