JPH11337005A - Octagonal cross section type boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an overall heat transfer efficiency between a combustion gas and feed water flowing through a heat exchanger tube in a side wall by achieving a formation in a regular ortagonal shape to almost uniformize the distance from the side wall the closest to the center part of a cross section to the apex formed between adjacent side walls and the distance. SOLUTION: In a boiler wherein a combustion gas produced by generating a spiral flow inside a furnace 11 to generate steam, the horizontal cross section thereof is formed in a regular octagon. As a result, the distance is almost uniform between the center 15 of the cross section of the boiler and positions across the width of a side wall 12 which has a heat exchanger tube formed in parallel for feeding feed water to achieve a better heat exchanger between the combustion gas and the feed whereby enhancing the evaluation of the performance in the boiler. This allows diversion of working and operation techniques of the conventional square shaped boiler and eliminates excessive accumulation of manufacturing costs of the boiler thereby enabling producing of a lower cost boiler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler used for thermal power generation and waste disposal, and more particularly to a boiler having an octagonal cross section and having heat transfer tubes juxtaposed from the center of the boiler. The octagonal cross-sectional shape is such that the distance to the side wall is made substantially uniform in the circumferential direction, and the heat transfer from the combustion gas that turns around the center of the boiler and burns to the heat transfer tubes is uniform and improved. About the boiler.

[0002]

2. Description of the Related Art Fuel and air are injected from a burner installed on a side wall formed by arranging heat transfer tubes side by side to a center of a boiler cross section and an offset, thereby obtaining a cross section in a furnace. Generate a swirling flow around the center, and make it a uniform mixed flow so that good combustion of fuel such as heavy oil and air occurs.
A boiler that generates high-temperature combustion gas in a furnace and heats water supplied through a heat transfer tube arranged side by side with the combustion gas to generate steam is used for thermal power generation or disposal. It is conventionally used for material processing and the like.

[0003] In such a boiler, there are some reasons from the viewpoint of production and operation of the boiler.
As shown in FIG. 2A, a boiler 01 having a substantially square cross section is used as the boiler cross section.
Further, in such a boiler 01, a heat transfer tube through which feed water for generating steam passes is arranged in parallel, and the side wall 02 of the side wall 02 having a substantially rectangular cross section is formed.
On each of the sides, a plurality of burners 03 are installed in a vertical direction at a position slightly deviated from the center position in the width direction of the side wall 02, and a fuel such as heavy oil is disposed in a direction orthogonal to the side wall 02 surface in plan view. And the air, and the flame 04 ignited by the pilot burner is jetted toward the center of the furnace 07.

Accordingly, a boiler 01 having a rectangular cross section is used.
Inside, the burner 03 is set off the center position in the width direction of the side wall 02, and the flame 04 is ejected into the furnace 07 substantially perpendicular to the side wall 02 surface. A swirling flame swirling around the center 05 is formed.

As described above, by performing combustion in the furnace 07 by generating a swirling flame centered on the center 05 of the cross section, the burner 03 also burns.
The air-fuel mixture is further mixed by the swirling flow about the center 5 of the cross-section so that the fuel and the air injected into the furnace 07 are mixed in the burner 03 by generating a swirling flow around the axis. And good combustion with a small amount of unburned components continues to occur, high-temperature combustion gas is generated at the center 05 of the cross-section, and good heat exchange with the water supply flowing through the side wall 02 is achieved. It is possible to generate steam efficiently.

[0006] In the performance evaluation of the boiler 01, in addition to the generation of the above-described good combustion gas having a small unburned content, the heat exchange property between the combustion gas and the feed water is an important factor. That is, this heat exchange property is equal to the side wall 0 of the boiler 01.
The heat transfer efficiency depends on the heat transfer efficiency between the feed water and the combustion gas inside the heat transfer tube forming the two surfaces, and the heat transfer efficiency depends on the heat transfer tube through which the feed water flows inside from the center 05 of the cross section where the combustion gas has the highest temperature. , In other words, the distance from the center 05 of the cross section to the side wall 02, and the distance between the center 05 of the cross section of the boiler 01 and the heat transfer tube forming the side wall 02 is an important factor.

The maximum / minimum value of this distance is 0
5 is determined by the distance between each vertex 06 of the cross-sectional shape and each position of each side wall 02. Therefore, the heat exchange property, which is an important factor in the performance evaluation of the boiler 01, is determined by the center of the cross-sectional center of the boiler 01.
5 is determined by the uniformity determined by the distance between each of the vertices 06 in the cross section and each position in the width direction of the side wall 02.

[0008] However, in the conventional boiler 01 having the above-described substantially square cross section, in particular,
As shown in FIG. 2B, the center 05 of the cross section of the boiler 01
When the distance between the center of the boiler 01 in the width direction and the center of the cross section 05 of the boiler 01 and the vertex 06 are l ′, l l '
And 1.0: √2 = 1.0: 1, 41, and the distance between the center 05 of the cross-section and each position in the width direction of the side wall 02 greatly varies. , Square side wall 0
2, the heat exchange property between the center portion 05 of the cross section and the vertex 06, and particularly, the portion of the side wall 02 near the vertex 06 becomes extremely non-uniform, resulting in poor performance and poor performance evaluation. Was.

[0009]

SUMMARY OF THE INVENTION The present invention relates to the above-mentioned disadvantages of the conventional boiler 01, namely, the vicinity of the center 05 of the cross section where the combustion gas generated in the furnace 07 becomes the hottest.
The distance between the side wall, in which the heat transfer pipes through which the feed water for heat exchange with the combustion gas flows, and particularly the vicinity of the top of the boiler where the distance from the vicinity of the center 05 of the cross section becomes the longest, is increased. In order to solve the problem that the heat exchange property is deteriorated, the uniform heat exchange between the combustion gas and the feed water is not performed, and the performance evaluation of the boiler is reduced, and further, there is no problem in manufacturing the boiler 01. The distance from the center 05 of the cross section of the boiler 01 to each position in the width direction including the apex of the side wall 02 is made as uniform as possible so that the combustion gas and the feed water flowing through the heat transfer tubes arranged side by side with the side wall 02 An object of the present invention is to provide an octagonal-section boiler in which the heat exchange property of the boiler is made as uniform as possible and the performance evaluation can be enhanced.

[0010]

For this reason, the octagonal section boiler of the present invention has the following means. By injecting a flame into the furnace, a swirling flow of the combustion gas swirling around the center of the cross section in the furnace is generated, and feed water is generated so as to generate steam by heat exchange with the combustion gas. The heat transfer tubes are arranged side by side, and the side walls on which the burners that inject the flame are installed are formed so that the horizontal distance from the center of the cross section in the furnace is substantially uniform The horizontal cross-sectional shape of the furnace was adjusted to be octagonal. The width of the side wall forming the octagon is
It is preferable that the respective lengths are made substantially uniform so that the horizontal cross-sectional shape of the furnace becomes a substantially regular octagon.

The octagonal cross-section boiler of the present invention has the above-described configuration, so that the distance between the center of the center of the cross-section in the furnace and the side wall closest to the center and the distance between the center of the cross-section and the center farthest from the center. The ratio with the distance between the vertices formed between the side walls to be formed can be made from 1: 1 and 41 in the case of a regular square to 1: 1 and 08 in the case of a regular octagon. The heat transfer coefficient important in the performance evaluation of the boiler is made uniform in the width direction of the side wall, and the side wall is composed of high-temperature combustion gas swirling around the center of the cross section in the furnace,
The heat exchange property to the heat transfer tube in which the supply water for generating steam flows inside is substantially uniform in the width direction of the side wall, the heat exchange is improved, and the performance evaluation of the boiler can be improved. It will be.

Further, from the viewpoint of workability, in the case of an octagonal boiler, as in the case of a regular square boiler, machining is facilitated. Production costs or operation costs, which are important factors, do not increase. That is, a boiler having a circular cross section in which the ratio of the distance between the center of the center of the cross section in the furnace and the side wall closest to the center and the distance between the center and the vertex farthest from the center is 1: 1 is considered. From the viewpoint that the heat exchange property from the combustion gas to the heat transfer tube becomes highest and the performance evaluation of the boiler is improved, the cross-sectional shape becomes the most preferable.

However, when the cross section of the boiler is made circular in this way, machining becomes extremely difficult, and the production cost of the boiler increases significantly. As in the case of performance evaluation, the cost of manufacturing that is an important evaluation target increases, and the improvement of performance evaluation is canceled, whereas in the case of an octagonal cross-section boiler, the case of a regular square boiler As in the case of (1), there is an advantage that the boiler can be manufactured at low cost and heat exchange property can be improved, and at the same time, the manufacturing cost and operation cost can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an octagonal section boiler of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a first embodiment of an octagonal section boiler of the present invention, and FIG. 1 (a) is a view showing a horizontal cross section of the octagonal section boiler of the present embodiment.

As shown in the figure, an octagonal-section boiler 10 of the present embodiment has a substantially regular octagonal cross-sectional shape in which eight side walls 12 have substantially the same width. Four sides sandwiching the other sides of the eight side walls 12, in which heat transfer tubes through which feed water for generating steam is passed are juxtaposed so that the cross-sectional shape of the furnace 11 is formed in a substantially regular octagon. On the upper side, the burner 13 is arranged so that the flame 14 discharged into the furnace 11 forms a swirling flame.

That is, of the eight side walls 12, one of the four side walls 12 is sandwiched between the four side walls 12, and a position deviated from the center position in the width direction of the four side walls 12 is a plurality of the vertical side walls. A plurality of burners 13 are installed, a fuel 14 such as heavy oil is mixed with air in a direction orthogonal to the side wall 12 surface on which the burners 13 are provided, and a flame 14 ignited by a pilot burner provided on the burners 13 is provided. The gas is blown out toward the center of the furnace 11. In other words, the octagonal cross section boiler 10 having an octagonal cross section has
Since the burners 13 are installed off the center in the width direction of the four side walls 12, and the flames 14 are ejected from the burners 13 into the furnace 11 in a direction substantially perpendicular to the side walls 12 on which the burners 13 are respectively installed. In the furnace 11, a flow of the flame 14 is generated at a position equally deviated from the center 15 of the cross section, and the flame 14 swirling around the center 15 of the cross section is formed.

It should be noted that the flame 14 is injected into the furnace 11 not necessarily in the horizontal direction, but the burner 13 is arranged on the side wall 12 so as to normally face upward.
, And a funnel-shaped swirling flow opening upward can also be generated. in this way,
By generating a swirling flame centered on the center 5 of the cross-section and performing combustion in the furnace 11, a swirling flow is generated around the axis of the burner 13 before being injected into the furnace 11. After the mixing of fuel and air is promoted to generate the mixture, the mixture of fuel and air injected into the furnace 11 is further promoted by the swirling flow swirling around the center 15 of the cross section. In the vicinity of the center 15 of the cross-section, good combustion with almost no unburned portion occurs, high-temperature combustion gas is generated, and the water supply and water flow through the heat transfer tubes arranged side by side constituting the side wall 12. Good heat exchange with the combustion gas is performed, and steam can be generated efficiently.

The octagonal cross-section boiler 10 generates good combustion gas with a small amount of unburned portion, and also has an important factor in the performance evaluation of the boiler. And the distance between the side wall 12 through which the supply water flows is substantially uniform, and the heat exchange between the supply water and the combustion gas inside each of the heat transfer tubes juxtaposed in the width direction of the side wall 12 is uniform, and the heat exchange property is improved. Become like

That is, for the distance 1 between the center 15 of the cross section of the octagonal cross-section boiler 10 and the center of the octagonal side wall 12, in other words, the position on the side wall 12 closest to the center 15 of the cross section. As shown in FIG. 1B, the ratio of the distance l 'between the center 15 of the cross section and the vertex 16 located farthest from the center 15 of the octagonal side wall 12 is 1.08, and FIG. In the case of the regular square boiler shown, it is made uniform from 1.41 by 0.33, so that more uniform heat transfer can be performed. In the octagonal cross-section boiler 10 of the present embodiment, the ratio of the distance between the closest position of the side wall 12 to the center 15 of the cross-section and the distance of the vertex 16 can be made more uniform than that of a boiler having a regular rectangular cross-section. Therefore, heat exchange between the combustion gas and the water supply in the heat transfer tube,
As a result, the heat exchange performance of the entire boiler, which is important in the performance evaluation of the boiler, can be improved.

Further, the workability, which is important in the evaluation of the boiler, together with the operation technology, is controlled by the octagonal cross section boiler
Since the technology of the conventional quadrangular boiler is fundamental, the octagonal cross-sectional shape boiler 10 can use these technologies of the already established quadrangular boiler, and is easy from the processing side, and the operation device is also simple. It can be diverted, and the boiler production cost does not increase, and it can be produced at low cost.

In the above-described embodiment, the lateral width of the side wall 12 forming the octagon is set at the center of the cross section in the furnace 11.
Although the horizontal distance from 5 is formed so as to be substantially uniform, and the horizontal cross-sectional shape of the furnace 11 is a regular octagon, the present invention is limited to such an embodiment. Not something. That is, as compared with the side wall 12 forming the horizontal cross-sectional shape of the octagonal furnace 11, the workability is more difficult and the processing cost is slightly increased. Alternatively, the furnace 11 may have a horizontal cross-sectional shape of a dodecagonal furnace 11 which is a multiple of 4 which can be diverted by the operation device.

[0022]

As described above, in the octagonal-section boiler of the present invention, a swirling flow of the combustion gas swirling is generated at the center of the cross section, and the heat is exchanged with the combustion gas to heat the feedwater to produce steam. The cross-sectional shape of the boiler that causes the boiler is most affected by the distance from the center of the cross-section to each position in the width direction of the side wall, in particular, the distance from the vertex formed between adjacent side walls and the center of the cross-section. The octagon is formed so that the distance from the approaching side wall is substantially uniform.

Thus, in the boiler having the octagonal cross-sectional shape of the present invention, the heat transfer coefficient important in the performance evaluation of the boiler becomes substantially uniform in the width direction of the side wall, so that the combustion gas and the water supply flowing through the heat transfer tube on the side wall are not mixed. The overall heat transfer coefficient is improved, the heat exchange property is improved, and the performance evaluation of the boiler can be improved. Also,
The octagonal cross-section of the production and operation costs, which are important in the evaluation of the boiler, as important as the performance evaluation, is as simple as that of a square boiler. It can be a cost boiler.

[Brief description of the drawings]

FIG. 1 is a view showing a cross-sectional shape of an octagonal-section boiler of the present invention, wherein FIG. 1 (a) is a plan view showing a cross-section, and FIG. 2 (b).
Is a diagram for explaining the distance between the center of the boiler transverse section and the apex formed between the side walls arranged adjacent to each other by forming an octagonal sectional shape,

2A and 2B are diagrams showing a cross-sectional shape of a conventional rectangular cross-section boiler, wherein FIG. 1A is a plan view showing a cross-section, and FIG. 2B is disposed adjacent to the center of the cross-section of the boiler. FIG. 6 is a diagram for explaining a distance from a vertex formed between side walls formed.

[Explanation of symbols]

 01 Boiler 02 Side wall 03 Burner 04 Flame 05 Center of cross section 06 Vertex 07 Furnace 10 Octagonal cross section boiler 11 Furnace 12 Side wall 13 Burner 14 Flame 15 Center of cross section 16 Vertex

Claims (1)

[Claims] A flame is injected into a furnace from a burner installed on a side wall formed by juxtaposed heat transfer tubes to generate a combustion gas swirling around a center of a cross section in the furnace. In a boiler that generates steam by heat exchange between feed water flowing in a heat pipe and the combustion gas,
An octagonal boiler, wherein the horizontal cross section of the furnace is formed in an octagonal shape, and the horizontal distance from the center of the cross section in the furnace to the side wall is substantially uniform.