JP7696235B2 - Tubular boiler - Google Patents

Description

This disclosure relates to a tubular boiler.

For example, various types of boilers are used to generate auxiliary steam on ships. A boiler mainly comprises a casing, a combustor, and a heat transfer tube. The high-temperature combustion gas generated by the combustor exchanges heat with the water flowing inside the heat transfer tube, heating the water and producing steam.

In the case of boilers used on ships, vibrations from various vibration sources such as the propeller and engine can be transmitted to the heat transfer tubes. If such vibrations are superimposed and cause resonance, this can affect the smooth operation of the boiler.

As a result, a configuration has been proposed in which a plate material called an anti-vibration baffle is inserted in the gap between the heat transfer tubes, as shown in the following Patent Document 1.

Japanese Patent Application Publication No. 9-264503

However, in a cylindrical boiler, a combustion gas flow is actively formed in the axial direction of the heat transfer tube, so when the above-mentioned vibration-proof baffle is used, the flow path cross-sectional area around the heat transfer tube is reduced. This can result in the combustion gas not being able to make sufficient contact with the heat transfer tube, which can reduce the efficiency of the boiler.

The present disclosure has been made to solve the above problems, and aims to provide a cylindrical boiler with reduced vibration, without impeding the flow of combustion gas, and with improved efficiency.

In order to solve the above problems, the cylindrical boiler according to the present disclosure includes a cylindrical casing extending in an axial direction, a combustor that generates combustion gas within the casing, and a heat transfer tube group provided within the casing and consisting of a plurality of heat transfer tubes that are exposed to the combustion gas, each of the heat transfer tubes having a heat transfer tube main body extending in the axial direction and a plurality of cylindrical projections that are provided so as to protrude from an outer circumferential surface of the heat transfer tube main body and are provided at intervals in the circumferential direction and the axial direction of the heat transfer tube, each of two adjacent heat transfer tubes has at least one first cylindrical projection having a circular tip surface, the first cylindrical projections of each of the two heat transfer tubes are provided at the same position in the axial direction and have respective tip surfaces that face each other with a gap therebetween, and the gap is large enough to allow the first cylindrical projections to come into contact with each other when vibration occurs .

This disclosure makes it possible to provide a cylindrical boiler with reduced vibration and improved efficiency without impeding the flow of combustion gas.

1 is a vertical cross-sectional view showing a configuration of a boiler according to a first embodiment of the present disclosure. 1 is a cross-sectional view showing a configuration of a boiler according to a first embodiment of the present disclosure. 1 is a cross-sectional view showing a configuration of a heat transfer tube according to a first embodiment of the present disclosure. FIG. 2 is a side view showing the configuration of a heat transfer tube according to the first embodiment of the present disclosure. FIG. 2 is an enlarged view showing the configuration of a heat transfer tube according to the first embodiment of the present disclosure. FIG. 4 is a cross-sectional view showing the configuration of a boiler according to a second embodiment of the present disclosure.

First Embodiment
(Configuration of tubular boiler)
Hereinafter, a cylindrical boiler 100 according to a first embodiment of the present disclosure will be described with reference to Fig. 1 to Fig. 5. The cylindrical boiler 100 is an apparatus that is disposed on a ship, for example, and used to generate auxiliary steam.

As shown in FIG. 1, the cylindrical boiler 100 includes a casing 1, an upper cover 2, a lower cover 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.

The casing 1 is cylindrical and centered on an axis O extending in the vertical direction. The upper end of the casing 1 is closed by an upper cover 2. The lower end of the casing 1 is closed by a lower cover 3. In addition, an exhaust section 8 is provided at a portion of the circumference of the casing 1 to guide the combustion gas discharged from the heat exchange space H (described later) to the outside.

A combustor 4 is attached to the upper cover 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, a cylindrical inner furnace wall 5 that forms the combustion chamber V on the inner circumferential side is provided inside the casing 1. The inner furnace wall 5 is cylindrical with the axis O as its center, and an opening h is formed in part of its circumferential direction. The inner furnace wall 5 is configured to be cylindrical overall by arranging cylindrical members in the circumferential direction and blocking the gaps between them with plate material.

On the outer periphery of the inner furnace wall 5, an outer furnace wall 6 is provided, which is cylindrical about the axis O and covers the inner furnace wall 5. Like the inner furnace wall 5, the outer furnace wall 6 is also configured to be cylindrical overall by arranging cylindrical members in the circumferential direction and blocking the gaps between them with plate materials.

The space surrounded by the inner furnace wall 5 and the outer furnace wall 6 is the heat exchange space H that houses the heat transfer tube group 70. The heat exchange space H has a circular cross-sectional shape centered on the axis O. Within this heat exchange space H, a plurality of heat transfer tubes 7 are arranged at intervals from one another.

(Configuration of heat transfer tube)
As shown in Fig. 3 to Fig. 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 main body 71 centered on a central axis A extending parallel to the axis line A of the casing, and a plurality of cylindrical protrusions 72 attached to the outer circumferential surface of the heat transfer tube main body 71. The inside of the heat transfer tube main body 71 is a flow path for water to flow. The cylindrical protrusions 72 are arranged at intervals on the outer circumferential surface of the heat transfer tube main body 71 in the circumferential direction about the central axis A, and are also arranged in a plurality of rows at intervals in the direction of the central axis A. In this embodiment, one row in the direction of the central axis A includes eight cylindrical protrusions 72.

Each cylindrical projection 72 protrudes radially from the outer circumferential surface of the heat transfer tube body 71. The cylindrical projection 72 has a circular cross-sectional shape, and the end surface (tip surface 72a) at the tip side is also circular (see FIG. 4). The tip surfaces 72a of the cylindrical projections 72 between adjacent heat transfer tubes 7 face each other with a gap. More specifically, these heat transfer tubes 7 are close enough that the cylindrical projections 72 can come into contact with each other when slight vibration occurs. In addition, the multiple cylindrical projections 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 projections 72 are provided at the same height position in the direction of the central axis A. Note that "same" and "parallel" here refer to substantially the same and parallel, and manufacturing errors and design tolerances are allowed.

(Action and Effect)
Next, the operation of the 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. In addition, water is caused to flow from the bottom to the top through the heat transfer tube 7. High-temperature combustion gas flows from the combustion chamber V into the heat exchange space H through an opening h formed in the inner furnace wall 5 (arrow in FIG. 2). The combustion gas that flows into the heat exchange space H exchanges heat with the water flowing inside the heat transfer tube 7. This heats the water and turns it into high-temperature steam. This steam is taken out to the outside and used for various purposes. In addition, the combustion gas that has completed the heat exchange is led to the outside through the exhaust section 8.

However, when using a cylindrical boiler 100 on a ship, vibrations may be transmitted to the heat transfer tube 7 from various vibration generating sources such as a propeller or engine. If such vibrations are superimposed and cause resonance, this may affect the smooth operation of the cylindrical boiler 100. Therefore, in this embodiment, a cylindrical protrusion 72 is provided on the heat transfer tube main body 71 as described above.

When vibration occurs in the heat transfer tube 7, a slight displacement occurs in the radial direction of the central axis A. This causes the tip faces 72a of adjacent cylindrical protrusions 72 to come into contact with each other. This allows the energy of the vibration to be dissipated, making it possible to dampen the vibration itself. Furthermore, the contact between the cylindrical protrusions 72 creates virtual fixed points between the heat transfer tubes 7. This changes the natural frequency of each heat transfer tube 7, making it possible to avoid the occurrence of resonance.

In addition, unlike plate-like members such as fins and baffles, the blockage of the flow path by the cylindrical protrusions 72 is minimized. This prevents the flow of combustion gas from being impeded, improving the efficiency of the cylindrical boiler 100. In particular, in the cylindrical boiler 100 according to this embodiment, as described above, the combustion gas flows in various directions within the heat exchange space V. Therefore, if fins or baffles are provided, the flow of the combustion gas in at least one direction will be impeded. However, with the cylindrical protrusions 72, the projected area is minimized when viewed from any direction, making it possible to minimize the impact on the flow of the combustion gas.

Furthermore, with the above configuration, the cylindrical protrusions 72 face each other with a gap between them, so that even slight displacement caused by vibrations can bring these cylindrical protrusions 72 into contact with each other.

In addition, with the above configuration, the cylindrical protrusions 72 are positioned at the same position along the central axis A, so that even slight vibrations can bring the cylindrical protrusions 72 into proper contact with each other.

In addition, with the above configuration, since the multiple cylindrical protrusions 72 overlap when viewed from the direction of the central axis A, 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 cylindrical protrusions 72 in the direction of the central axis A can be minimized. This allows the combustion gas to flow smoothly.

Furthermore, according to the above configuration, since the cylindrical protrusions 72 have a circular tip surface 72a, it is possible for these cylindrical protrusions 72 to come into contact with each other more reliably than when, for example, the tip portions are formed in a pointed shape. This makes it possible to more reliably damp vibrations.

The above describes the first embodiment of the present disclosure. 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 above first embodiment, an example was described in which eight cylindrical projections 72 are provided in one row in the direction of the central axis A. However, the number of cylindrical projections 72 is not limited to eight, and may be seven or less or nine or more. In addition, the arrangement of the heat transfer tubes 7 described based on FIG. 2 is one example, and can be changed as appropriate depending on the design and specifications.

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 description will be omitted. As shown in Fig. 6, in this 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, the cylindrical protrusions 72 of the heat transfer tubes 7 are omitted for the sake of simplicity.

The inner furnace wall 5b and the outer furnace wall 6b are polygonal (an octagonal shape, for example) when viewed from the axis O direction. The inner furnace wall 5b and the outer furnace wall 6b are formed by welding eight plate materials together. Although not shown in detail, in this embodiment, as in the first embodiment, such plate materials may be formed by arranging a plurality of cylindrical members at intervals and blocking the gaps with plate materials. A plurality of heat transfer tubes 7 are arranged between the inner furnace wall 5b and the outer furnace wall 6b. More specifically, these heat transfer tubes 7 are arranged so as to be 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 between the plurality of heat transfer tubes 7.

According to the above configuration, the inner furnace wall 5b and the outer furnace wall 6b are polygonal. This allows the number of heat transfer tubes 7 to be installed to be increased compared to, for example, a case in which these furnace walls are cylindrical. This allows the cylindrical boiler 100 to be made smaller. Furthermore, multiple heat transfer tubes 7 are arranged so as to be parallel to the inner furnace wall 5b and the outer furnace wall 6b. This allows the lengths of the cylindrical protrusions 72 of each heat transfer tube 7 to be uniform.

On the other hand, if these furnace walls are cylindrical, the length of the cylindrical protrusions 72 must be changed depending on the location, which increases manufacturing and maintenance costs. The above configuration reduces this possibility, making it possible to reduce manufacturing and maintenance costs.

The above describes the second embodiment of the present disclosure. 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 above second embodiment, an example was described in which the inner furnace wall 5b and the outer furnace wall 6b are octagonal in shape. However, the shapes of the inner furnace wall 5b and the outer furnace wall 6b are not limited to this, and may be other regular polygons.

<Additional Notes>
The cylindrical boiler 100 described in each embodiment can be understood, for example, as follows.

(1) The cylindrical boiler 100 according to the first aspect includes a cylindrical casing 1 extending in the axial direction O, a combustor 4 that generates combustion gas within the casing 1, and a group of heat transfer tubes 7 provided within the casing 1 and 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 that are provided to protrude from the outer circumferential surface of the heat transfer tube body and are spaced apart in the circumferential direction and the axial direction of the heat transfer tube.

According to the above configuration, when vibrations occur in the heat transfer tube, adjacent cylindrical protrusions come into contact with each other based on the displacement caused by the vibrations. This allows the vibrations themselves to be damped. Furthermore, the contact between the cylindrical protrusions creates virtual fixed points between the heat transfer tubes. This changes the natural frequency of the heat transfer tube, making it possible to avoid the occurrence of resonance. Also, unlike plate-like members such as fins, blockage of the flow path by the cylindrical protrusions is kept to a minimum. This prevents the flow of combustion gas from being impeded, improving the efficiency of the cylindrical boiler.

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

With the above configuration, the cylindrical protrusions face each other with a gap between them, so that even slight displacement caused by vibrations can bring these cylindrical protrusions into contact with each other.

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

With the above configuration, the cylindrical protrusions are positioned in the same axial direction, so even slight vibrations can bring the cylindrical protrusions into proper contact with each other.

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

With the above configuration, since the multiple cylindrical protrusions overlap when viewed from the axial direction, it is possible to minimize blockage of the combustion gas flow path in the axial direction.

(5) In the fifth aspect of the cylindrical boiler 100, the cylindrical protrusion has a circular tip surface.

With the above configuration, the cylindrical protrusions have a circular tip surface, so that these cylindrical protrusions can come into contact with each other more reliably than when, for example, the tips are formed into a pointed shape.

(6) The cylindrical boiler 100 according to the sixth aspect further comprises an inner furnace wall that is provided within the casing, has a cylindrical shape centered on the axis, and 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 that accommodates the heat transfer tubes, the inner furnace wall and the outer furnace wall having a polygonal shape when viewed from the axial direction, and the multiple 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.

According to the above configuration, the inner furnace wall and the outer furnace wall are polygonal. This allows the number of heat transfer tubes to be increased compared to when, for example, these furnace walls are formed cylindrically. This allows the cylindrical boiler to be made smaller. Furthermore, multiple heat transfer tubes are arranged parallel to the inner furnace wall and the outer furnace wall. This allows the length of the cylindrical protrusions of each heat transfer tube to be uniform. On the other hand, if these furnace walls are cylindrical, the length of the cylindrical protrusions must be changed depending on the location, which increases manufacturing and maintenance costs. The above configuration reduces this possibility and allows manufacturing and maintenance costs to be reduced.

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

Claims (4)

A cylindrical casing extending in an axial direction;
a combustor that generates combustion gas within the casing;
a heat transfer tube group provided within the casing, the heat transfer tube group including a plurality of heat transfer tubes and exposed to the combustion gas;
Equipped with
Each of the heat transfer tubes is
A heat transfer tube body extending in the axial direction;
a plurality of cylindrical projections provided at intervals in the circumferential direction and the axial direction of the heat transfer tube, the cylindrical projections being provided so as to protrude from the outer circumferential surface of the heat transfer tube body;
having
Each of the two adjacent heat transfer tubes has at least one first cylindrical projection having a circular tip end surface, the first cylindrical projections of the two heat transfer tubes are provided at the same position in the axial direction, and the tip ends of the first cylindrical projections face each other with a gap therebetween,
The gap is large enough to allow the first cylindrical projections to come into contact with each other when vibration occurs . 2. The cylindrical boiler according to claim 1 , wherein the cylindrical projections provided on one of the heat transfer tube bodies overlap each other when viewed from the axial direction. The cylindrical boiler according to claim 1 or 2 , wherein the cylindrical projection has a circular tip surface. an inner furnace wall provided in the casing, having a cylindrical shape centered on the axis, and forming a combustion chamber through which the combustion gas flows;
an outer furnace wall that covers the inner furnace wall from the outside and forms a heat exchange space that accommodates the heat transfer tube;
Further equipped with
The inner furnace wall and the outer furnace wall have a polygonal shape when viewed from the axial direction,
4. The cylindrical boiler according to claim 1, wherein when the heat transfer tubes adjacent to the outer furnace wall are viewed from their axial direction, a line connecting the centers of the heat transfer tubes is arranged in the heat exchange space so as to be parallel to the inner furnace wall and the outer furnace wall.

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