boiler

Abstract

The objective is to provide a boiler that can efficiently recover heat from exhaust gas without reducing boiler efficiency, even when the heat transfer area is small. [Solution] A boiler comprising a group of water tubes arranged in a ring around a combustion space, allowing combustion gas to flow out of the ring through the gaps between adjacent water tubes; a guide section that guides the combustion gas flowing out of the ring along the water tubes; and an outer wall that surrounds the guide section, collecting the combustion gas flowing out of the guide section and guiding it to a discharge duct. At least one water tube is provided with a vertical fin extending from its side so as to create a gap of a predetermined interval on the outer side of the ring of the water tube adjacent to that water tube, and the guide section guides the combustion gas flowing out from the predetermined gap between the water tube and the vertical fin along the water tube.

Description

Technical Field

[0001] The present invention relates to a boiler.

Background Art

[0002] Conventionally, a boiler provided with heat transfer promoting fins extending in the radial direction of each water pipe on the outer peripheral side of a water pipe row defining a combustion chamber is known. By providing the heat transfer promoting fins, heat recovery from combustion gas flowing through the gas flow gaps formed between the water pipes is promoted (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional boiler provided with heat transfer promoting fins, the combustion gas flowing out from the gas flow gaps formed between the water pipes diverges, resulting in a decrease in the can body efficiency. In particular, in the case of a boiler with a small heat transfer area, the can body efficiency tends to decrease easily.

[0005] The present invention has been conceived in view of such circumstances, and its object is to provide a boiler capable of efficiently recovering heat from combustion gas.

Means for Solving the Problems

[0006] To achieve the above objective, a boiler according to a certain aspect of the present invention comprises a group of water tubes arranged in a ring around a combustion space, allowing combustion gas to flow out of the ring through gaps between adjacent water tubes; a guide section that guides the combustion gas flowing out of the ring along the water tubes; and an outer wall that surrounds the guide section, collecting the combustion gas flowing out of the guide section and guiding it to a discharge duct. At least one of the water tubes is provided with a longitudinal fin extending from its side so as to create a gap of a predetermined interval on the outer side of the water tube adjacent to it, and the guide section guides the combustion gas flowing out of the predetermined gap between the water tube and the longitudinal fin along the water tube.

[0007] With the above configuration, the combustion gas is guided along the water tube by the guide unit, thereby promoting heat recovery on the side of the water tube opposite the guide unit. As a result, heat recovery from the combustion gas can be performed efficiently.

[0008] Preferably, the guide portion is an annular backing plate surrounding the group of water tubes, and is in contact with the tip of the longitudinal fin or the outer side of the water tube ring.

[0009] With the above configuration, heat can be efficiently recovered from combustion gases with a simple structure.

[0010] Preferably, the guide portion is a cylindrical member that surrounds and covers the group of water tubes.

[0011] According to the above configuration, for example, the guide portion can be generated by a simple processing method such as bending a single thin plate-like member into a cylindrical shape.

[0012] Preferably, the vertical length of the guide section is made shorter than the vertical length of the water pipe group, and the combustion gas flowing out of the ring is guided to the discharge duct via the outer wall.

[0013] With the above configuration, the guide section is shorter than the water pipe group in terms of vertical length, so that section acts as an opening, allowing combustion gases flowing out of the ring to be efficiently guided to the exhaust duct.

[0014] Preferably, a spacer is provided on the side surface of the water tube that forms the gap between the longitudinal fin and the predetermined interval, and the spacer is in contact with the inner side surface of the longitudinal fin, and the guide portion is provided at each of the predetermined interval gaps.

[0015] With the above configuration, the guide section is placed very close to the water pipe, which further promotes heat transfer, and the exhaust gas flows circumferentially, resulting in a more uniform exhaust gas flow. Furthermore, the use of spacers makes it easy to manage the predetermined gap spacing.

[0016] Preferably, the guide portion abuts against the inner side surface of the longitudinal fin and the spacer.

[0017] With the above configuration, a gap is easily formed between the side of the water tube and the longitudinal fin, that is, the flow of exhaust gas from the exhaust gas outlet to the guide section is easily formed, preventing external leakage of exhaust gas. In addition, the guide section can be fixed in place by the longitudinal fin and the spacer. [Brief explanation of the drawing]

[0018] [Figure 1] This is a diagram illustrating a longitudinal cross-sectional view of a boiler according to the present invention. [Figure 2] This is a schematic cross-sectional view of the boiler when it is cut along the ZZ line in Figure 1, as seen from above. [Figure 3] This is a schematic cross-sectional view of the area around the water tubes when viewed from above in a boiler. [Modes for carrying out the invention]

[0019] <Outline of the structure> Hereinafter, referring to FIGS. 1 and 2, the schematic configuration of the boiler 1 according to an embodiment of the present invention will be described. Note that the present invention is not limited to these examples, and is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included in the present invention.

[0020] FIG. 1 shows a can body 2 that burns fuel to generate steam among the components included in the boiler 1. The can body 2 is formed in a substantially cylindrical shape, and includes a burner 3 that burns fuel therein, a plurality of water pipes 9, an upper header 7, a lower header 8, and the like. The plurality of water pipes 9 are each connected between the upper header 7 and the lower header 8. Although an example in which the fuel is a gas such as gas will be described, the fuel is not limited to gas and may be a liquid such as oil.

[0021] As shown in FIG. 2, the plurality of water pipes 9 are annularly accommodated inside the can body 2 and are erected at predetermined intervals in the circumferential direction of the can body 2. Vertical fins 17 are provided on the side surfaces of all the water pipes 9 over the longitudinal direction of the water pipes 9. In addition, at predetermined upper and lower positions on the side surfaces of the water pipes 9, spacers 19 are provided that abut against the side surfaces of adjacent water pipes 9 (in this case, the water pipes 9 located clockwise) and create a gap corresponding to the thickness (predetermined interval) (not shown in FIG. 2. Refer to the spacer 19 in FIG. 1 and FIG. 3 described later). The side surfaces of the water pipes 9 and the vertical fins 17 of the water pipes 9 are both arranged so as to abut against the spacers 19 of the adjacent water pipes 9 (in this case, the water pipes 9 located counterclockwise). For this reason, a predetermined interval gap corresponding to the thickness of the spacer 19 is created between the side surfaces of adjacent water pipes 9 and between the side surfaces of adjacent water pipes 9 and the vertical fins 17. The spacer 19 has a function of managing the interval between the water pipe 9 and the vertical fins 17 provided on the side surface of the adjacent water pipe to a constant width. As a result, the combustion gas burned in the combustion chamber (combustion space) 4 at the substantially central portion of the can body 2 flows out of the ring through the gaps between the plurality of water pipes 9, is led to the exhaust duct 11 from the exhaust port 15, and is discharged to the outside of the can body 2.

[0022] The guiding part 18 is an annular contact plate surrounding a plurality of groups of water pipes 9, and an example of contacting the tip of the vertical fin 17 is shown in FIG. 2. The guiding part 18 guides the combustion gas flowing out of the gap between the water pipe 9 and the vertical fin 17 to flow along the adjacent water pipe 9 (in this case, the water pipe 9 located counterclockwise). The guiding part 18, which is an annular contact plate, is, for example, a cylindrical member covering the group of water pipes 9, and can be constructed by a simple method of bending a single thin plate member into a cylindrical shape. As shown in FIG. 1, the vertical length of the guiding part 18 is shorter than the vertical length of the group of water pipes 8. The part (upper end part) where the guiding part 18 is shorter than the group of water pipes 9 serves as an opening for allowing the combustion gas to flow out to the outer wall 16 side. The outer wall 16 surrounds the guiding part 18 and collects the combustion gas flowing out of the guiding part 18 and guides it to the exhaust duct 11. Thereby, an upward exhaust gas flow is generated, the flow velocity outside the ring of the water pipe 9 can be expanded, and the combustion gas flowing out of the ring can be efficiently guided to the exhaust duct 11.

[0023] The burner 3 is provided above the combustion chamber 4. The burner 3 heats the canned water introduced into the plurality of water pipes 9 to generate steam. Further, combustion air is supplied to the burner 3 from an air supply device, and fuel gas is supplied from a fuel supply device. The air supply device includes a blower, and the fuel supply device includes a flow rate adjustment valve. The combustion amount of the boiler 1 is continuously or stepwise adjusted by controlling the blower and the flow rate adjustment valve in a manner corresponding to the combustion state (combustion amount) by a control device that controls the operation and operation of the boiler 1. For example, when the combustion state is a high combustion state, the opening degree of the flow rate adjustment valve is controlled to 100%, and when the combustion amount is lower than the high combustion state and is in a low combustion state, the opening degree of the flow rate adjustment valve is controlled to 50%.

[0024] The lower header 8 is located at the bottom of the boiler body 2 and is connected to the lower parts of multiple water pipes 9. The lower header 8 is connected to a water supply pipe 10 that supplies water to the boiler body 2. Upstream of the water supply pipe 10, a water supply pump and a check valve (neither of which are shown) are provided. Water sent from the water supply pump through the water supply pipe 10 is supplied to the lower header 8 from the water inlet 14. The supplied water is heated in the water pipes 9.

[0025] The upper header 7 is located at the top of the boiler body 2 and is connected to the tops of multiple water pipes 9. The upper header 7 has the function of collecting steam generated in the multiple water pipes 9 and water pushed up with the steam, and separating it into dry steam and water (steam-water separation). The dry steam separated in the upper header 7 is sent to designated equipment via the steam supply pipe 6. On the other hand, the water separated in the upper header 7 is returned to the lower header 8 via the downdraft pipe 12 that connects the upper header 7 and the lower header 8. This allows boiler water to be circulated in addition to the circulation that takes place in the upper header 7, which will be described later. A blowdown pipe 13 for discharging boiler water from the boiler body 2 is connected to the downdraft pipe 12. A blowdown valve 13a is provided in the blowdown pipe 13. By opening the blowdown valve 13a, boiler water can be discharged (blowdown) from the boiler body 2.

[0026] Combustion gases from the combustion of fuel in the combustion chamber 4 pass through the gaps between the multiple water tube groups 9 (between adjacent water tubes 9), through the gap between the outside of the water tubes 9 (outside the ring of the water tube group 9) and the guide section 18, flow along the outer side of the water tubes 9 by the guide section 18, are discharged from above the guide section 18 towards the outer wall 16, and are led out to the exhaust duct 11 from the exhaust port 15. At this time, the combustion gases exchange heat with the water in the multiple water tubes 9, and the water in the multiple water tubes 9 is heated. In this embodiment, the combustion gases that have passed through the gaps between the multiple water tube groups 9 are guided along the side of the water tubes 9 by the guide section 18 so that they do not dissipate, so that heat recovery can be performed efficiently. For example, even a boiler with a small heat transfer area due to a simple structure can efficiently recover heat from combustion gases without reducing the boiler efficiency. The water heated in the multiple water tubes 9 becomes steam and is supplied from the upper header 7 to various devices that use steam via the steam supply pipe 6.

[0027] The present invention is not limited to the embodiments described above, and various modifications and applications are possible. Below, we will describe some modifications of the above embodiments applicable to the present invention.

[0028] In the above embodiment, an example was described in which the annular backing plate, the guide portion 18, abuts against the tip of the vertebral fin 17. However, it is not limited to this, and in cases where the length from the base of the vertebral fin 17 (the side of the water canal) to the tip of the vertebral fin 17 is short, for example, only long enough to reach the position where the tip of the vertebral fin 17 abuts against an adjacent water canal 9 (in this case, a counterclockwise water canal), the annular backing plate, the guide portion 18, may abut against the sides of multiple water canals 9 instead of the tip of the vertebral fin 17, or it may abut against either the tip of the vertebral fin 17 or the sides of multiple water canals 9.

[0029] In the above embodiment, an example was described in which the guide portion 18, which is an annular backing plate, is processed by curving a single thin plate-like member. However, it may be composed of multiple members instead of just one. Alternatively, it may be processed using a corrugated plate-like member with bends, or a member with perforations or slits may be used. Furthermore, an example was described in which the opening (the part where the guide portion 18 is shorter than the group of water pipes 9) is provided at the upper end. However, the opening may be provided only at the lower end, or it may be provided at a total of two locations, at the upper and lower ends. Alternatively, the guide portion 18, which is an annular backing plate, may be divided into upper and lower halves, with openings at the upper end, lower end, and also in the center, resulting in a total of three openings.

[0030] In the above embodiment, an example was described in which the guide portion 18 is an annular backing plate, but instead, a guide portion 18 with the structure shown in Figure 3 may be provided. Figure 3 is a schematic cross-sectional view of the area near the water tubes of the boiler. Figure 3(a) shows a horizontal cross-section of the water tube 9 where the spacer 19 is provided, and Figure 3(b) shows a horizontal cross-section of the water tube 9 where the spacer 19 is not provided. In Figure 3(b), the area without the spacer 19 is shown by a dotted line, and this area becomes the passage for combustion gas.

[0031] In Figure 3, the guide portion 18 is a thin, strip-shaped plate member whose vertical length (parallel to the longitudinal direction of the water tube 9) is approximately the same as the vertical length (longitudinal direction) of the water tube 9, and whose horizontal shape is R-shaped (for example, with a central angle of 60 degrees) along the circumference of the water tube 9. The guide portion 18 is provided at each gap between the water tube 9 and the longitudinal fin 17, and is positioned to abut both the inner side surface of the longitudinal fin 17 and the spacer 19, with one side of the guide portion 18 inserted into these gaps. The other end of the guide portion 18 may be fixed at the top and bottom with, for example, a claw component, a band, or a castable. This prevents the guide portion 18 from bending outwards. In this structure, because the guide portion 18 is provided at a position very close to the water tube 9, the heat transfer efficiency is further promoted, and the combustion gas flow is made uniform because the combustion gas flows in the circumferential direction. Furthermore, the gap between the side of the water tube 9 and the vertical fin 17 (the outlet for combustion gas) facilitates the flow of combustion gas to the guide section 18, preventing external leakage of combustion gas. In addition, the vertical fin 17 and the spacer 19 have the effect of fixing the guide section 18 in place.

[0032] In the above embodiment, an example was described in which the water pipe group 9 is arranged in a single ring, as shown in Figure 2. However, the water pipe group 9 may also have a double ring structure consisting of an inner water pipe group and an outer water pipe group surrounding the outside of the inner water pipe group. In this case, the configuration related to the guide section 18 shown in Figures 1 to 3 may be applied to the outer water pipe group.

[0033] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0034] 1 Boiler 2 can body 3 burners 4 Combustion chamber 5. Combustion gas passage 6. Steam supply pipe 7. Top Header 8. Bottom Header 9 water tube 10 Water supply pipe 11. Exhaust duct 12 Downpipe 13. Blowdown piping 13a Blow-off valve 14 Water inlet 15 Exhaust vent 16 Exterior Wall 17 Vertical fins 18 Guidance part 19 Spacers

Claims

1. A group of water tubes is arranged in a ring around the combustion space, allowing combustion gases to flow out of the ring through the gaps between adjacent water tubes. A guide unit that guides the combustion gas flowing out of the ring along the water pipe, The system includes an outer wall that surrounds the aforementioned guide section and collects the combustion gas flowing out from the guide section and guides it to a discharge duct. At least one of the water tubes has a longitudinal fin that extends from its side to create a gap of a predetermined interval on the outer side of the adjacent water tube. The guide unit is a boiler that guides combustion gas flowing out from the predetermined gap between the water tube and the longitudinal fin along the water tube.

2. The boiler according to claim 1, wherein the guide portion is an annular backing plate surrounding the water tube group, and abuts against the tip of the longitudinal fin or the outer side of the water tube ring.

3. The boiler according to claim 2, wherein the guide section is a cylindrical member that surrounds and covers the group of water tubes.

4. The boiler according to claim 3, wherein the vertical length of the guide section is shorter than the vertical length of the water tube group, and the combustion gas flowing out of the ring is guided to the discharge duct via the outer wall.

5. A spacer is provided on the side surface of the water tube that forms the gap between the longitudinal fin and the predetermined distance, and which abuts against the inner side surface of the longitudinal fin. The boiler according to claim 1, wherein the induction section is provided at each of the predetermined intervals.

6. The boiler according to claim 5, wherein the guide portion abuts against the inner side surface of the longitudinal fin and the spacer.

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