JPH08110002A - Water tube boiler - Google Patents

Abstract

PURPOSE: To provide a small-sized, light-weighted water tube boiler with an enhanced heat-transfer efficiency. CONSTITUTION: In a water tube boiler wherein combustion gas is made to flow crosswise with regard to water tubes 3, there are provided water tube walls 4 disposed oppositely to one another, a burner 6 for injecting the combustion gas in an approximately horizontal direction between the water tube walls 4, 4 and water tube groups 7 protruding in an opposite side from the water tube wall 4 and arranged in line so as to form a tapered combustion chamber 5. Small clearances 9 are provided between the water tubes of the water tube walls 7 so as to allow the combustion gas to flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water tube boiler, and more particularly to a vertical water tube boiler in which water tubes are arranged substantially vertically and combustion gas is flowed in a crossing direction.

[0002]

2. Description of the Related Art A conventional vertical water tube boiler generally has a structure in which a water tube wall is formed in a cylindrical shape or a rectangular shape, a burner is attached to one end, and the inside thereof serves as a combustion chamber. However,
In many cases, among the vertical water pipes arranged in a cylindrical shape or a rectangular shape, few water pipes effectively receive heat from the combustion chamber in which the flame exists, and there was much wasted space in terms of heat transfer efficiency. Recently, boilers have been required to improve heat transfer efficiency and be small and lightweight in order to save space.
Similarly low NO _X of the exhaust gas from the environmental issues, low CO gasification has been demanded.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a water tube boiler having improved heat transfer efficiency and reduced size and weight. Furthermore, low N
Is O _X reduction, and low CO gas concentration of, and Takaden thermal efficiency,
An object is to provide a water tube boiler that is small and lightweight.

[0004]

In order to solve the above problems, a water tube boiler according to a first aspect of the present invention is a water tube boiler in which combustion gas flows in a direction intersecting with a water tube. A burner for ejecting the combustion gas in a substantially horizontal direction between the water pipe walls, and a burner which projects from the water pipe wall to the opposite side to the burner and forms a combustion chamber which is tapered in the flow direction of the combustion gas. It is characterized in that it is provided with one row of water pipe groups provided, and a small gap for flowing out combustion gas is provided between the water pipes of the water pipe group.

The water tube boiler of the second aspect of the present invention is
In a water tube boiler for flowing combustion gas in a direction intersecting with a water tube, water tube walls facing each other, a burner for ejecting combustion gas in a substantially horizontal direction between the water tube walls, and a burner from the water tube wall opposite to the burner. And a row of water tubes arranged so as to form a combustion chamber that is tapered in the direction of combustion gas flow, and has a slight gap between the water tubes of the water tube group, through which the combustion gas flows out. A combustion chamber surrounded by the water pipe wall and a row of water pipe groups, wherein a plurality of water pipes is further arranged on the burner side, and the water pipe forms a tapered combustion chamber with the water pipe. It is characterized in that a space is provided between the group and the group.

[0006]

According to the first aspect of the present invention, the combustion chamber which is tapered in the flow direction of the combustion gas is constituted by the water pipe wall and the row of water pipes, and between the water pipes of the tapered portion of the combustion chamber. Since the combustion gas is caused to flow out from the slight gap, effective heat transfer can be performed in the water tube wall and the one row of water tube groups by the effect of the impinging jet heat transfer. Here, the impinging jet heat transfer is heat transfer accompanied by the high temperature combustion gas directly hitting the surface of the water pipe, and a high heat transfer effect can be obtained. Since a large number of water pipes can be arranged in the tapered portion of the combustion chamber as compared with the rectangular parallelepiped combustion chamber, the heat transfer efficiency in the furnace can be increased, and the boiler can be reduced in size and weight.

According to the second aspect of the present invention, since a plurality of water pipes are arranged on the burner side of the tapered combustion chamber,
Lowering the temperature of the flame, it is possible to reduce the NO _X reduction. A turbulent flow is generated in the combustion gas in the plurality of water pipes in the center of the combustion chamber, and a space is provided between the water pipes and the row of water pipes forming the tapered combustion chamber. CO gas is oxidized to CO ₂ gas. As a result, the heat transfer efficiency is improved, the boiler is made smaller and lighter, and the exhaust gas is low N
O _X, it is possible to provide a water tube boiler low CO gas concentration.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a transverse sectional view of a water tube boiler according to a first embodiment of the present invention, and FIG. 2 is an elevation view. This boiler is a vertical type water tube boiler in which combustion gas is caused to flow in an intersecting direction with respect to a standing water tube. The water pipe wall 4 is provided with a pair of water pipe walls 4 facing each other and arranged substantially parallel to each other. The water pipe wall 4 is formed by connecting the water pipes 3 to each other. That is, the water pipe wall 4 means a furnace wall composed of water pipes, and is a Tangent tube arrangement in which bare water pipes are closely arranged, or a panel structure in which bare water pipes are connected by fins. The burner 6 is arranged in the upstream portion between the pair of water pipe walls 4 and 4 so that the combustion gas flows between the pair of water pipe walls 4 and 4 substantially in parallel. Each of the water pipes 3 and 3 is provided with a water pipe group 7 that projects from the pair of water pipe walls 4 and 4 to the opposite side of the burner and is arranged in a V shape.
A slight gap 9 is provided between them. The combustion gas burned in the burner 6 flows out from the gap 9 and is discharged to the flue 11. Reference numeral 10 is a casing. Therefore, the combustion chamber 5 is a space surrounded by the pair of water pipe walls 4, 4 and the row of water pipes 7 projecting in a V shape on the opposite side, and the flow of the combustion gas. It is tapered in the direction. Water is supplied to each water pipe 3 from the lower pipe head (lower body) 2, heated in each water pipe 3, becomes hot water or steam, and is taken out from the upper pipe body (upper body) 1.

The operation of this boiler is as follows. In the burner 6, the fuel gas mixes with the air pushed by a blower (not shown) and burns to generate a flame 20. The burner 6 is preferably a short-flame flame burner, for example, but is not limited to this, and may be another premixing burner or a premixing burner. Combustion gas 21
Is jetted into the combustion chamber 5 and directly hits the surface of the water pipe 3 projecting into the tapered combustion chamber 5, heat-exchanges with a collision jet, and then a slight gap between the water pipes 3 of the water pipe group 7 in one row. 9 goes out of the combustion chamber 5. Even when the combustion gas 21 flows through this slight gap 9, heat is exchanged with the surface of the water pipe 3. After the combustion reaction is completed in the combustion chamber 5, the combustion gas 21 flowing out of the combustion chamber 5 through the slight gap 9 reduces the amount of combustion gas passing through the tapered combustion chamber 5 toward the downstream side. . Corresponding to this, the combustion chamber 5 is also gradually narrowed and has a tapered shape, so that the gas flow velocity passing through the tapered portion of the combustion chamber 5 is kept high and the heat transfer coefficient is a V-shaped water pipe group. 7
It is possible to maintain a high value in each water pipe 3 of. Then, all of the combustion gas 21 directly hits the surface of each water pipe 3 forming the tapered combustion chamber 5 in the vertical direction, so that effective heat transfer can be performed in this region by the collision jet heat transfer effect. Then, when the combustion gas exits the combustion chamber 5, it can flow at high speed on the surface of the water pipes forming the small gaps 9 between the water pipes 3 to further perform heat transfer. And
Since there are many small gaps 9 between the water pipes, the ventilation resistance can be significantly reduced while maintaining high heat transfer, the power of the blower can be reduced, and a low noise and energy saving boiler can be obtained. You can As described above, in this embodiment, the combustion gas directly hits a large number of water pipes 3 forming the tapered combustion chamber 5, and the heat transfer effect of passing through a small gap between the water pipes 3 increases the heat transfer efficiency in the furnace. Can be one.

FIG. 3 is a cross-sectional view of the water tube boiler of the second embodiment of the present invention. In this embodiment, the water pipe walls 4 and 4 facing each other are arranged so as to be substantially in the same row as the row of water pipes 7 in which the combustion chamber 5 is tapered.
The arrangement of the water pipe group 7 in one row is the same as that of the first embodiment of the present invention. In this way, by arranging the water pipe walls 4, 4 and the water pipe group 7 in one row in a taper shape on a substantially straight line (in a V shape as a whole), the boiler can can be further downsized.

FIG. 4 is a cross sectional view of a water tube boiler according to a third embodiment of the present invention. In this embodiment, a row of water pipes 12 is further provided outside the row of water pipes 7 in which the combustion chamber 5 has a tapered shape. FIG. 5 shows a water tube boiler according to a fourth embodiment of the present invention, in which water tube groups 13 are further arranged in a zigzag form in one row outside the water tube group 12 in the second row. Due to the arrangement of the second row water pipe group 12 and the third row water pipe group 13, the combustion gas 21 that has flowed through the gap 9 between the water pipes 3
The jet heat transfer and the convective heat transfer can further exchange heat and remove heat from the combustion gas. That is, as shown in FIG. 5, the maximum temperature of the outer peripheral portion of the flame 20 is 1500 ° C. or higher,
The temperature of the combustion gas passing through the first row water tube group 7, the second row water tube group 12, and the third row water tube group 13 becomes lower than that in the case of FIG. 1, and is discharged to the flue 11. In this way, 1 tube
Rows or more than two rows, for example staggered, water pipe groups 12, 13
By providing the above, the water pipes 3 can be densely arranged without lengthening the boiler can in the flow direction of the combustion gas, and a space-saving compact boiler can can be obtained. If the slight gaps 9 between the water pipes are made substantially equal to each other, the heat transfer on the surface of the water pipes can be maintained at a high value in any water pipe.

FIG. 6 is a cross sectional view of a water tube boiler according to a fifth embodiment of the present invention. In this embodiment, the water pipes 4 and 4 facing each other are arranged in a V-shape. That is, the three water pipes from the burner side are arranged in a tangent tube arrangement in close contact with each other, and the three water pipes on the downstream side are connected by fins to form a panel structure having a shallow V-shape. Then, one row of water tube groups 7 is arranged in a taper shape (V-shape) from the central portion of the water tube walls 4 and 4, and a second row of water tube groups 12 is arranged outside thereof.
Are arranged, and further, the third row water pipe group 13 is arranged outside. As in the above-mentioned embodiment, a gap is provided between each of the water pipes forming the group of water pipes for passing combustion gas. Such a water pipe wall 4 and a water pipe group 7, 1
Due to the arrangement of 1 and 12, the combustion gas entering through the gap between any of the water tubes of the water tube group 7 in the first row conducts heat transfer with the water tubes at the same number of times and is discharged to the flue 11. Therefore, it is possible to uniformly remove heat from the combustion gas, which is particularly effective in a large capacity boiler.

FIG. 7 shows a modification of the third embodiment of the present invention, in which each water pipe 3 of the second row water pipe group 12 is a finned water pipe 14. The finned water pipe 14 is provided with a large number of ribs on the water pipe 3, and can increase the heat transfer area to further improve the heat transfer efficiency. In the case of a boiler having a large combustion amount, the water pipe group 12 up to the second row may be the water pipes without fins, and the third and subsequent rows may be the water pipes with fins.

FIG. 8 shows that the heat transfer promoter 15 is arranged in the gap 9 portion of the water tube group 7 in the first row of the water tube boiler of the first embodiment of the present invention. The heat transfer accelerator 15 is made by bending a V-shaped heat-resistant material such as stainless steel and arranged in a valley between the water pipes 3 with a slight gap. As a result, the dead heat transfer surface on the back surface of the water pipe is utilized to further enhance the convective heat transfer effect on the surface of the water pipe 3 outside the combustion chamber 5. FIG. 9 shows a water pipe boiler according to the third embodiment of the present invention in which a heat transfer promoter 15 is attached along the back surface of each water pipe 3 of the second row water pipe group 12 in the valley of each water pipe. By flowing the combustion gas along the back surface of the water tube group 12 in the second row, the heat transfer to the water tubes in the second row is further improved.

FIG. 10 shows a water tube boiler according to a sixth embodiment of the present invention. This boiler is provided with a plurality of water pipes 23 (here, three) in the combustion chamber 5 of the boiler of the third embodiment. The water pipe 23 has two water pipes arranged in the center of the combustion chamber 5 close to the burner 6 and one water pipe arranged downstream along the gas flow. A space 24 is provided downstream of the water pipe 23 and between the water pipe group 7 in the first row. By this water pipe 23, the turbulent flow intensity of the combustion gas can be increased, and residual CO can be oxidized into CO ₂ gas in the space 24 between the plurality of water pipes 23 and the water pipe group 7 in the first row. With such a structure, the oxidation reaction of the CO gas is completed in the tapered combustion chamber 5, and the boiler can body having a low CO gas concentration can be obtained. In this case, flame 2
The maximum temperature of the peripheral portion of 0 is 1500 ° C. or higher, the combustion gas is deheated in the water pipe 23 and becomes a turbulent state, and enters the CO oxidation region 24. The temperature of this part is 1000-1500
C., and the CO gas can be CO ₂ gas.

FIG. 11 shows a modification of the sixth embodiment of the present invention, in which the number of water pipes 23 in the combustion chamber 5 is 3 from the burner 6 side.
There are two, two, and so on. This water pipe 23A is
Since the number of the water pipes 23 is larger than that of the above-mentioned water pipes 23, the turbulence effect becomes finer, and the CO oxidation region 24 becomes wider than the embodiment shown in FIG. 10 as shown in the drawing.

FIG. 12 shows a water tube boiler of the seventh embodiment of the present invention. The structure of this embodiment is almost the same as that of the above-mentioned sixth embodiment, but the water pipe 23B is arranged so that a part thereof is located in the flame 20. Water tube 2 in flame 20
Since part of the water pipe 3B is located, the flame 20 is cooled and the flame temperature is lowered. As a result, the generation concentration of NO _x can be reduced, and the boiler can have a low NO _x concentration. Further, in the CO oxidation region 24 in the combustion chamber 5 surrounded by the tapered water pipe group 7, the residual CO is oxidized to reduce the NO.
_X , a boiler body with low CO performance. According to such a water pipe arrangement, it is possible to secure the region 24 in which CO can be oxidized without enlarging the cross-sectional area of the gas passage in the combustion chamber, so that the combustion chamber can be reasonably balanced.

The CO oxidation area 24 for oxidizing CO is
A large combustion chamber is not required, and the tapered combustion chamber 5 has a small volume, which is suitable for this space and has a low C
A space-saving boiler can can be obtained based on O performance.

Although several examples of the present invention have been described above, the number of water pipes and the like are not limited to this example, and may be appropriately changed in consideration of the size of the boiler and the like. Of course. Further, it goes without saying that a fourth row or a fifth row may be added to the second row and third row water tube groups arranged on the downstream side of the combustion gas of the tapered water tube group 7. As described above, various modified embodiments are possible without departing from the spirit of the present invention.

[0021]

According to the present invention as described above,
By making the shape of the combustion chamber taper with respect to the gas flow direction and allowing the combustion gas to flow out from the slight gaps between the water pipes, heat can be effectively transferred to a large number of water pipes.
As a result, the heat transfer efficiency is significantly improved, and a small and lightweight water tube boiler can be provided. Further, by arranging the water pipe group in the portion close to the flame in the tapered combustion chamber, the flame is cooled and a turbulent flow effect is generated in the combustion gas.
The gas can be oxidized in the space downstream thereof. Thus NO _X, it is possible to provide a vertical water tube boiler small and lightweight Takaden thermal efficiency lowered CO gas concentration.

[Brief description of drawings]

FIG. 1 is a transverse sectional view of a water tube boiler according to a first embodiment of the present invention.

FIG. 2 is an elevation view of the water tube boiler shown in FIG.

FIG. 3 is a cross sectional view of a water tube boiler according to a second embodiment of the present invention.

FIG. 4 is a transverse sectional view of a water tube boiler according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view of a water tube boiler according to a fourth embodiment of the present invention.

FIG. 6 is a transverse sectional view of a water tube boiler according to a fifth embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a modified example of the third embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a modified example of the first embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a modification of the third embodiment of the present invention.

FIG. 10 is a transverse sectional view of a water tube boiler according to a sixth embodiment of the present invention.

FIG. 11 is a transverse sectional view showing a modification of the sixth embodiment of the present invention.

FIG. 12 is a transverse sectional view of a water tube boiler according to a seventh embodiment of the present invention.

[Explanation of symbols]

 1 Upper pipe head (or upper shell) 2 Lower pipe pipe (or lower shell) 3 Water pipe 4 Water pipe wall 5 Combustion chamber 6 Burner 7 Tapered (first row) water pipe group 9 Water pipe gap 10 Casing 11 Flue 12 Water Tube Group in Second Row 13 Water Tube Group in Third Row 14 Water Tube with Fins 15 Heat Transfer Accelerator

Claims (9)

[Claims] 1. A water tube boiler for flowing combustion gas in a direction intersecting with a water tube, water tube walls facing each other, a burner for ejecting combustion gas in a substantially horizontal direction between the water tube walls, and the water tube. A row of water pipes arranged so as to project from the wall to the side opposite to the burner and to form a combustion chamber that is tapered in the direction of flow of the combustion gas. Combustion gas is provided between the water pipes of the water pipe group. A water tube boiler characterized by having a small gap that flows out. 2. The water tube boiler according to claim 1, further comprising one or more rows of water tubes arranged at a downstream side of the combustion gas of the one row of water tubes with a slight gap. 3. The water pipe boiler according to claim 1, wherein the water pipe group is further provided with a heat transfer promoting member that forms a gas passage having a slight gap. 4. The water pipe boiler according to claim 2, wherein a part or all of the further arranged one or more rows of water pipes are finned water pipes. 5. In a water tube boiler for flowing combustion gas in a direction intersecting with the water tube, water tube walls facing each other, a burner for ejecting combustion gas in a substantially horizontal direction between the water tube walls, and the water tube. A row of water pipes arranged so as to project from the wall to the side opposite to the burner and to form a combustion chamber that is tapered in the direction of flow of the combustion gas. Combustion gas is provided between the water pipes of the water pipe group. A combustion chamber surrounded by the water pipe wall and a row of water pipe groups, which has a slight gap to flow out, and a plurality of water pipes is further arranged on the burner side to form the water pipe and the tapered combustion chamber. A water tube boiler characterized in that a space portion is provided between the water tube group and a row of water tube groups. 6. The water pipe group of one row or two or more rows is further arranged at a slight gap downstream of the combustion gas of the water tube group of one row forming the tapered combustion chamber. Item 5. The water tube boiler according to item 5. 7. The water pipe boiler according to claim 5, wherein a part of the water pipe in the combustion chamber is arranged in a combustion flame generated from the burner. 8. The water pipe boiler according to claim 5, wherein the water pipe group is further provided with a heat transfer promoting member that forms a gas passage having a slight gap. 9. The water pipe boiler according to claim 5, wherein a part or all of the further arranged one or more rows of water pipes are finned water pipes.