Cylindrical boiler

Abstract

To provide a cylindrical boiler which achieves reduction of vibration, prevents combustion gas flow from being hindered, and achieves further improvement of efficiency.SOLUTION: A cylindrical boiler includes: a casing forming a cylindrical shape extending in an axial direction; a combustor which generates a combustion gas within the casing; and a heat transfer pipe group which is provided within the casing, comprises multiple heat transfer pipes, and is subject to the combustion gas. Each heat transfer pipe has: a heat transfer pipe body extending in the axial direction; and multiple columnar protrusions which are provided so as to protrude from an outer peripheral surface of the heat transfer pipe body and spaced apart from each other in a circumferential direction of the heat transfer pipe and the axial direction.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a cylindrical boiler.

Background Art

[0002] For example, various boilers are used for generating auxiliary steam in ships. A boiler mainly includes a casing, a combustor, and heat transfer tubes. High-temperature combustion gas generated by the combustor exchanges heat with water flowing inside the heat transfer tubes, thereby heating the water to obtain steam.

[0003] By the way, in the case of a boiler used on a ship, vibration may be transmitted from various vibration sources such as a propeller and an engine to the heat transfer tubes. If such vibrations are superimposed to cause resonance, it may affect the smooth operation of the boiler.

[0004] Therefore, as shown in Patent Document 1 below, a configuration has been proposed in which a plate material called an anti-vibration baffle is interposed in the gap between the heat transfer tubes.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in a cylindrical boiler, since a combustion gas flow is actively formed in the axial direction of the heat transfer tubes, when the above anti-vibration baffle is used, the flow path cross-sectional area around the heat transfer tubes decreases. As a result, the combustion gas may not sufficiently contact the heat transfer tubes, and there is a risk that the efficiency of the boiler may decrease.

[0007] The present disclosure has been made to solve the above problems, and an object thereof is to provide a cylindrical boiler in which vibration is reduced, the combustion gas flow is not inhibited, and the efficiency is further improved.

Means for Solving the Problems

[0008] In order to solve the above problems, the cylindrical boiler according to the present disclosure includes a casing having a cylindrical shape extending in the axial direction, a combustor that generates combustion gas within the casing, and a heat transfer tube group provided within the casing and composed of a plurality of heat transfer tubes that are exposed to the combustion gas. Each of the heat transfer tubes has a heat transfer tube body extending in the axial direction and a plurality of cylindrical protrusions provided so as to protrude from the outer peripheral surface of the heat transfer tube body and spaced apart from each other in the circumferential direction and the axial direction of the heat transfer tube. Moreover, each of two adjacent heat transfer tubes has at least one first columnar protrusion having a circular tip surface, and the first columnar protrusions of each of the two heat transfer tubes are provided at the same position in the axial direction and their tip surfaces face each other with a gap therebetween, and the gap is such that the first columnar protrusions can contact each other when vibration occurs. 。

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a cylindrical boiler in which vibration is reduced, the combustion gas flow is not inhibited, and the efficiency is further improved.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0011] <First Embodiment> (Configuration of Cylindrical Boiler) Hereinafter, the cylindrical boiler 100 according to the first embodiment of the present disclosure will be described with reference to FIGS. 1 to 5. The cylindrical boiler 100 is a device that is disposed, for example, on a ship and is used to generate auxiliary steam.

[0012] As shown in FIG. 1, the cylindrical boiler 100 includes a casing 1, an upper lid 2, a lower lid 3, a combustor 4, an inner furnace wall 5, an outer furnace wall 6, a heat transfer tube group 70, and an exhaust section 8.

[0013] The casing 1 has a cylindrical shape centered on an axis O extending in the vertical direction. The upper end of the casing 1 is closed by the upper lid 2. The lower end of the casing 1 is closed by the lower lid 3. Further, an exhaust section 8 for guiding the combustion gas discharged from the heat exchange space H described later to the outside is provided at a part of the circumferential direction of the casing 1.

[0014] The combustor 4 is attached to the upper lid 2. The combustor 4 generates high-temperature combustion gas by forming a flame toward the inside of the casing 1 (inside the combustion chamber V). As shown in FIG. 2, inside the casing 1, a cylindrical inner furnace wall 5 that forms a combustion chamber V on the inner peripheral side is provided. The inner furnace wall 5 has a cylindrical shape centered on the axis O, and an opening h is formed in a part of its circumferential direction. The inner furnace wall 5 is configured to form a cylindrical shape as a whole by arranging columnar members in the circumferential direction and closing the gaps therebetween with plate materials.

[0015] An outer furnace wall 6 that covers the inner furnace wall 5 by forming a cylindrical shape centered on the axis O is provided on the outer peripheral side of the inner furnace wall 5. Similar to the inner furnace wall 5, the outer furnace wall 6 is configured to form a cylindrical shape as a whole by arranging columnar members in the circumferential direction and closing the gaps therebetween with plate materials.

[0016] The space surrounded by the inner furnace wall 5 and the outer furnace wall 6 is a heat exchange space H for accommodating the heat transfer tube group 70. The heat exchange space H has an annular cross-sectional shape centered on the axis O. A plurality of heat transfer tubes 7 are arranged at intervals within this heat exchange space H.

[0017] (Configuration of the heat transfer tube) As shown in FIGS. 3 to 5, the heat transfer tube group 70 has a plurality of heat transfer tubes 7. Each heat transfer tube 7 has a cylindrical heat transfer tube body 71 centered on a central axis A extending parallel to the axis A of the casing, and a plurality of cylindrical protrusions 72 attached to the outer peripheral surface of the heat transfer tube body 71. The interior of the heat transfer tube body 71 is a flow path for water to flow. The cylindrical protrusions 72 are arranged at intervals in the circumferential direction with respect to the central axis A on the outer peripheral surface of the heat transfer tube body 71, and are also arranged in a plurality of rows at intervals in the direction of the central axis A. In the present embodiment, one row in the direction of the central axis A includes eight cylindrical protrusions 72.

[0018] Each cylindrical protrusion 72 protrudes radially from the outer peripheral surface of the heat transfer tube body 71. The cylindrical protrusion 72 has a circular cross-sectional shape, and the end face on the tip side (tip face 72a) is also circular (see FIG. 4). Between adjacent heat transfer tubes 7, the tip faces 72a of the cylindrical protrusions 72 face each other with a gap therebetween. More specifically, these heat transfer tubes 7 are close enough that the cylindrical protrusions 72 can contact each other when slight vibration occurs. Also, the plurality of cylindrical protrusions 72 provided on one heat transfer tube body 71 overlap each other when viewed from the direction of the central axis A. Furthermore, between adjacent heat transfer tubes 7, the cylindrical protrusions 72 are provided at the same height position in the direction of the central axis A. Here, the terms "same" and "parallel" refer to substantial sameness and parallelism, and manufacturing errors and design tolerances are allowed.

[0019] (Function and effect) Next, the operation of the above-described cylindrical boiler 100 will be described. When operating the cylindrical boiler 100, first, the combustor 4 is operated to form a flame F and generate combustion gas. Also, water is made to flow through the heat transfer tubes 7 from below upward. The high-temperature combustion gas flows from the combustion chamber V into the heat exchange space H through the opening h formed in the inner furnace wall 5 (arrow in Fig. 2). The combustion gas that has flowed into the heat exchange space H exchanges heat with the water flowing inside the heat transfer tubes 7. As a result, the water is heated to become high-temperature steam. This steam is taken out to the outside and used for various purposes. Further, the combustion gas that has completed heat exchange is led to the outside through the exhaust section 8.

[0020] Incidentally, when the cylindrical boiler 100 is used on a ship, vibration may be transmitted from various vibration sources such as a propeller and an engine to the heat transfer tubes 7. If such vibration is superimposed and resonance occurs, it may affect the smooth operation of the cylindrical boiler 100. Therefore, in the present embodiment, the cylindrical projections 72 are provided on the heat transfer tube main body 71 as described above.

[0021] When vibration occurs in the heat transfer tubes 7, a slight displacement occurs in the radial direction of the central axis A. Then, the tip surfaces 72a of the cylindrical projections 72 adjacent to each other come into contact. As a result, the energy of the vibration is dissipated, and it becomes possible to attenuate the vibration itself. Further, due to the contact between the cylindrical projections 72, a virtual fixed point is generated between the heat transfer tubes 7. As a result, the natural frequency of each heat transfer tube 7 changes, so that the occurrence of resonance can be avoided.

[0022] Further, unlike plate-like members such as fins and baffles, the blockage of the flow path by the columnar protrusions 72 is minimized. As a result, the flow of the combustion gas is not obstructed, and the efficiency of the cylindrical boiler 100 can be improved. In particular, in the cylindrical boiler 100 according to the present embodiment, as described above, in the heat exchange space V, the combustion gas flows in various directions. For this reason, when fins or baffles are provided, the flow of the combustion gas in at least one direction is obstructed. However, in the case of the columnar protrusions 72 described above, since the projected area is minimized when viewed from any direction, it is possible to minimize the influence on the flow of the combustion gas.

[0023] Furthermore, according to the above configuration, since the columnar protrusions 72 face each other with a gap therebetween, even a slight displacement due to vibration can bring these columnar protrusions 72 into contact with each other.

[0024] In addition, according to the above configuration, since the positions of the columnar protrusions 72 in the direction of the central axis A are the same, even a slight vibration can bring these columnar protrusions 72 into appropriate contact with each other.

[0025] Also, according to the above configuration, since the plurality of columnar protrusions 72 overlap when viewed from the direction of the central axis A, the blockage of the combustion gas flow path in the direction of the central axis A can be minimized. In other words, the projected area of the columnar protrusions 72 in the direction of the central axis A can be minimized. As a result, it is possible to smoothly circulate the combustion gas.

[0026] Furthermore, according to the above configuration, since the columnar protrusions 72 have circular tip surfaces 72a, it is possible to more reliably bring these columnar protrusions 72 into contact with each other compared to the case where the tip portions are formed in a pointed shape, for example. As a result, vibration can be more reliably attenuated.

[0027] The first embodiment of the present disclosure has been described above. As long as the gist of the present disclosure is not deviated from, various changes and modifications can be made to the above configuration. For example, in the above first embodiment, an example in which eight cylindrical protrusions 72 are provided in one column in the direction of the central axis A has been described. However, the number of the cylindrical protrusions 72 is not limited to eight, and may be seven or less or nine or more. Further, the arrangement of the heat transfer tubes 7 described with reference to FIG. 2 is an example, and can be appropriately changed according to the design and specifications.

[0028] <Second Embodiment> Next, a second embodiment of the present disclosure will be described with reference to FIG. 6. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted. As shown in FIG. 6, in the present embodiment, the shapes of the inner furnace wall 5b and the outer furnace wall 6b and the arrangement of the heat transfer tubes 7 are different from those in the first embodiment. In FIG. 6, for the sake of simplicity of illustration, the illustration of the cylindrical protrusions 72 of the heat transfer tubes 7 is omitted.

[0029] The inner furnace wall 5b and the outer furnace wall 6b are polygonal (octagonal as an example) when viewed from the direction of the axis O. These inner furnace wall 5b and outer furnace wall 6b are formed by welding eight plate materials to each other. Although not shown in detail, in the present embodiment as well, similar to the first embodiment, a plurality of cylindrical members may be arranged at intervals, and such a plate material may be formed by closing the gaps with plate materials. A plurality of heat transfer tubes 7 are arranged between such an inner furnace wall 5b and an outer furnace wall 6b. More specifically, these heat transfer tubes 7 are arranged parallel to the inner furnace wall 5b and the outer furnace wall 6b. In other words, the distance between the outermost heat transfer tube 7 and the outer furnace wall 6b and the distance between the innermost heat transfer tube 7 and the inner furnace wall 5b are constant among the plurality of heat transfer tubes 7.

[0030] According to the above configuration, the inner furnace wall 5b and the outer furnace wall 6b are polygonal. Thereby, for example, compared with the case where these furnace walls are formed in a cylindrical shape, the number of heat transfer tubes 7 that can be laid can be increased. Thereby, it becomes possible to reduce the size of the cylindrical boiler 100. Further, a plurality of heat transfer tubes 7 are arranged so as to be parallel to the inner furnace wall 5b and the outer furnace wall 6b. Thereby, it becomes possible to make the lengths of the columnar protrusions 72 of each heat transfer tube 7 uniform.

[0031] On the other hand, when these furnace walls are cylindrical, the length of the columnar protrusion 72 has to be changed depending on the location, which increases the manufacturing cost and the maintenance cost. According to the above configuration, such a possibility is reduced, and the manufacturing cost and the maintenance cost can be reduced.

[0032] As described above, the second embodiment of the present disclosure has been described. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure. For example, in the second embodiment described above, an example in which the inner furnace wall 5b and the outer furnace wall 6b are octagonal has been described. However, the shapes of the inner furnace wall 5b and the outer furnace wall 6b are not limited to this, and other regular polygons may be used.

[0033] <Appendix> The cylindrical boiler 100 described in each embodiment is understood as follows, for example.

[0034] (1) The cylindrical boiler 100 according to the first aspect includes a casing 1 having a cylindrical shape extending in the direction of the axis O, a combustor 4 that generates combustion gas inside the casing 1, and a heat transfer tube group provided inside the casing 1 and composed of a plurality of heat transfer tubes 7 and exposed to the combustion gas. Each of the heat transfer tubes has a heat transfer tube body extending in the axial direction and columnar protrusions provided so as to protrude from the outer peripheral surface of the heat transfer tube body and provided in plurality at intervals in the circumferential direction and the axial direction of the heat transfer tube.

[0035] According to the above configuration, when vibration occurs in the heat transfer tube, adjacent cylindrical protrusions come into contact based on the displacement caused by the vibration. As a result, the vibration itself can be attenuated. Furthermore, due to the contact between the cylindrical protrusions, virtual fixed points are generated between the heat transfer tubes. This changes the natural frequency of the heat transfer tube, thus avoiding the occurrence of resonance. Also, different from a plate-like member such as a fin, for example, the blockage of the flow path by the cylindrical protrusions is minimized. This prevents the flow of combustion gas from being obstructed, and the efficiency of the cylindrical boiler can be improved.

[0036] (2) In the cylindrical boiler 100 according to the second aspect, between a plurality of adjacent heat transfer tubes, the cylindrical protrusions face each other with a gap therebetween.

[0037] According to the above configuration, since the cylindrical protrusions face each other with a gap therebetween, even a slight displacement due to vibration can bring these cylindrical protrusions into contact with each other.

[0038] (3) In the cylindrical boiler 100 according to the third aspect, between a plurality of adjacent heat transfer tubes, the cylindrical protrusions are provided at the same position in the axial direction.

[0039] According to the above configuration, since the positions of the cylindrical protrusions in the axial direction are the same, even a slight vibration can properly bring these cylindrical protrusions into contact with each other.

[0040] (4) In the cylindrical boiler 100 according to the fourth aspect, a plurality of the cylindrical protrusions provided on one heat transfer tube body overlap each other when viewed from the axial direction.

[0041] According to the above configuration, since a plurality of cylindrical protrusions overlap each other when viewed from the axial direction, the blockage of the combustion gas flow path in the axial direction can be minimized.

[0042] (5) In the cylindrical boiler 100 according to the fifth aspect, the cylindrical protrusion has a circular tip surface.

[0043] According to the above configuration, since the columnar protrusions have circular tip surfaces, it is possible to more surely bring these columnar protrusions into contact with each other compared to the case where the tip portions are formed in a pointed shape, for example.

[0044] (6) The cylindrical boiler 100 according to the sixth aspect is provided in the casing, has a cylindrical shape centered on the axis, and includes an inner furnace wall that forms a combustion chamber through which the combustion gas flows, and an outer furnace wall that covers the inner furnace wall from the outside and forms a heat exchange space for accommodating the heat transfer tubes. The inner furnace wall and the outer furnace wall have a polygonal shape when viewed from the axial direction, and the plurality of heat transfer tubes are arranged in the heat exchange space so as to be parallel to the inner furnace wall and the outer furnace wall.

[0045] According to the above configuration, the inner furnace wall and the outer furnace wall have a polygonal shape. As a result, for example, compared to the case where these furnace walls are formed in a cylindrical shape, the number of heat transfer tubes that can be laid can be increased. Thereby, it becomes possible to reduce the size of the cylindrical boiler. Further, the plurality of heat transfer tubes are arranged so as to be parallel to the inner furnace wall and the outer furnace wall. Thereby, it becomes possible to make the lengths of the columnar protrusions of each heat transfer tube uniform. On the other hand, when these furnace walls are formed in a cylindrical shape, the length of the columnar protrusions has to be changed depending on the location, resulting in an increase in manufacturing cost and maintenance cost. According to the above configuration, such a possibility is reduced, and the manufacturing cost and maintenance cost can be reduced.

Explanation of Reference Numerals

[0046] 100 Cylindrical boiler 1 Casing 2 Upper lid 3 Lower lid 4 Combustor 5, 5b Inner furnace wall 6, 6b Outer furnace wall 7 Heat transfer tube 8 Exhaust portion 70 Heat transfer tube group 71 Heat transfer tube body 72 Columnar projection 72a Tip surface A Central axis F Flame h Opening H Heat exchange space O Axis V Combustion chamber

Claims

1. A casing having a cylindrical shape extending in the axial direction, A combustor that generates combustion gas within the casing, A heat transfer tube group provided within the casing, comprising a plurality of heat transfer tubes and exposed to the combustion gas, and comprising: Each of the heat transfer tubes has a heat transfer tube body extending in the axial direction, and a plurality of cylindrical protrusions provided so as to protrude from the outer peripheral surface of the heat transfer tube body, with gaps in the circumferential direction and the axial direction of the heat transfer tube, and has: Each of two adjacent heat transfer tubes has at least one first cylindrical protrusion having a circular tip surface, and the first cylindrical protrusions of each of the two heat transfer tubes are provided at the same position in the axial direction and their tip surfaces face each other with a gap therebetween, and the gap is such that the first cylindrical protrusions can contact each other when vibration occurs, a cylindrical boiler.

2. The cylindrical boiler according to claim 1, wherein a plurality of the cylindrical protrusions provided on one heat transfer tube body overlap each other when viewed from the axial direction.

3. The cylindrical boiler according to claim 1 or 2, wherein the cylindrical protrusion has a circular tip surface.

4. An inner furnace wall provided within the casing, having a cylindrical shape centered on the axis and forming a combustion chamber through which the combustion gas flows, and an outer furnace wall that covers the inner furnace wall from the outside and forms a heat exchange space for housing the heat transfer tubes, and further comprising: The inner furnace wall and the outer furnace wall are polygonal when viewed from the axial direction, When the centers of the plurality of the heat transfer tubes adjacent to the outer furnace wall are connected by a line when viewed from their axial directions, the line is arranged to be parallel to the inner furnace wall and the outer furnace wall within the heat exchange space, for the cylindrical boiler according to any one of claims 1 to 3.

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