JPH0781683B2 - Vertical boiler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention provides a plurality of heat collecting water pipes in a combustion chamber of a cylindrical inner can of a vertical boiler constituted by a cylindrical outer can and an inner can. Therefore, the heat transfer efficiency of the vertical boiler is increased and the volume occupied by the combustion chamber of the vertical boiler is reduced to achieve downsizing and weight reduction.
The present invention relates to a vertical boiler that can suppress the generation of ash as much as possible.

[Conventional technology]

Conventional so-called well-known boilers have separate smoke tubes and water tubes installed in the upper part of the combustion chamber, and there are well-known ones such as cochrane boilers. It was A vertical boiler (Japanese Patent Laid-Open No. 62-242703) recently filed by the applicant has a remarkably simple and high efficiency which is composed of a cylindrical outer can and an inner can as shown in FIGS. 9 and 10. A vertical cylindrical inner can with a partially open top and bottom is inserted into a vertical cylindrical outer can whose upper and lower sides are closed. The cylindrical inner can defines left and right sides of the combustion chamber and the downstream side. One or more rows of water pipes for standing are set up, a gas passage is left at one end of the water tube row or at an appropriate place between the water tube rows, and a water tube group is set up on the downstream side.

On the other hand, as shown in FIG. 9 and FIG. 10 also in the stand-up boiler of the invention of the earlier application, after the fuel is burned in the combustion chamber space, the combustion gas passes through between the water pipes and is discharged to the outside. As a result, the space required for the combustion chamber in the entire boiler is large, and therefore the vertical boiler body is significantly large.

[Problems to be Solved by the Invention]

Conventional vertical boiler and prior invention of the applicant (Japanese Patent Laid-Open No. 62-24270)
In No. 3) as well, the combustion chamber and the water pipe were designed to surround the combustion flame from the outside, and the combustion space was secured according to the flame shape.

This required space volume is determined by the combustion chamber, heat addition, and heat transfer surface heat load, but in the case of small and medium capacity vertical boilers, the property of the burner, that is, the shape of the flame, is the decisive factor, and therefore a large space is required. I was crying. When fuel is burned in such a large space, a high temperature portion is formed in the central portion of the flame, which increases the amount of NOx produced, which may cause pollution problems.

It is an object of the present invention to increase the efficiency of a boiler, reduce the size of a vertical boiler, and suppress the generation of NOx by disposing many heat collecting water pipes in the combustion chamber.

[Means for Solving the Problems]

The present invention relates to a vertical boiler constituted by a cylindrical outer can and an inner can, wherein a vertically-arranged vertical outer can is inserted into the vertically closed outer can and the vertical cylindrical inner can is inserted. To provide a vertical boiler in which a plurality of heat collecting water pipes are arranged in the entire space of the combustion chamber in the inner can, or a space is provided by omitting only a part of the heat collecting water pipe near the burner of the vertical boiler. is there.

However, from the basic research results by the present inventors, (a) When a heat collecting water pipe arranged in the combustion chamber is hit with a flame, the flame is certainly cooled within 1 mm of the water pipe surface, and unburned components and CO are generated. However, due to the spacing of several tens of millimeters between the water pipes, unburned matter and CO burn and disappear in this part.

(B) Comparing the case of the present invention with a heat collecting water pipe with the combustion in a large space of a conventional type boiler, by arranging the heat collecting water pipe, the flow around the heat collecting water pipe, especially the wake of the water pipe The generation of vortex flow promotes the above combustion, and the distance from the burner head to the disappearance of unburned components and CO (the length of the flame) becomes shorter and shorter. Is more effective. Also, the cooling of the flame by the heat collecting water pipe greatly contributes to the suppression of NOx generation.

(C) The heat collecting water pipes present in the flame receive radiant heat transfer from the surroundings almost uniformly, but the effective thickness of the radiant gas layer is extremely small unlike the conventional large space combustion, so the amount of heat transfer is conventional. Compared to the mold, it is less, but contact heat transfer by gas flow is larger.

It has been found.

The heat transfer surface heat load distribution around the heat collecting water pipe according to the present invention
Shown in the figure. In Fig. 8, (9) is convective heat transfer (Qc),
(10) is radiant heat transfer (Qr) and total heat transfer surface heat load (Qr + Qc) is below the critical heat transfer surface heat load that does not cause burnout, and is almost uniform over the entire circumference of the heat collecting water pipe. .

In the present invention, depending on the characteristics of the burner, for example, when a diffusion type premix burner is used, the diameter (D) of the burner head, from the burner head to the heat collecting water pipe in the combustion chamber should be maintained so as not to impair the flame holding performance of the burner itself. Stable combustion of the burner is achieved by setting the shortest distance of (L) to L / D ≧ 1. Further, in the present invention, in order to improve the contact heat transfer effect of the heat collection water pipes in the combustion chamber, it is necessary to make the flow velocity of the heat collection water pipes to a certain degree fast, but if it is too fast, the pressure loss becomes large, and the combustion fan The gap between the water pipes (P) due to the increase in power and the inability to obtain a cross-sectional area perpendicular to the flow direction required for combustion, which causes problems in combustion.
It is necessary to set the ratio P / S of the water pipe diameter (S) to about 1.1 or more. In order to promote the combustion of the heat collecting water pipes, it is more effective to arrange the water pipes in a staggered arrangement rather than the staggered arrangement as described above.

Also, in the heat collecting water pipe in the combustion chamber, a bare pipe is used for the high heat transfer surface heat load part depending on the characteristics of the burner, or a groove is provided inside the heat collecting water pipe or the outer surface is heat-insulated to reduce the heat. By providing fins on the outer surface of the heat transfer surface heat load portion, it is effective in terms of both preventing fuel loss on the heat transfer surface and promoting heat transfer.

〔Example〕

 The present invention will now be described with reference to the drawings.

FIG. 1 is a cross-sectional view of an embodiment of a vertical boiler according to the present invention, in which a vertical cylindrical inner can (2) is inserted into a vertical cylindrical outer can (1), which is a prior application of the present applicant. Invention (JP-A-62-242703)
In order to improve the thermal efficiency of the boiler by improving (see FIG. 9 and FIG. 10) and to reduce the size and NOx of the boiler, the structure of the vertical boiler of the present invention is simplified and the combustion chamber (3 )
It is a densely packed heat collection water pipe (5b). FIG. 2 is a vertical cross-sectional view of FIG. 1, in which a standing fin (2) having a membrane structure for defining a combustion chamber (3) and a downstream water pipe group (5a) on the left and right is provided in the standing cylindrical inner can (2). 8) An attached defining water pipe (4) is erected while leaving a gas passage (10) at the end. The fuel gas burned by the burner (6) burns in the combustion chamber (3), and the combustion gas is a downstream water pipe group (5a) defined by the endothermic water pipe group (5b) and the water pipe (4). Through the exhaust port (7). FIG. 3 shows a structure in which the standing fins (8) shown in FIG. 2 are eliminated and the water pipes (1) are closely arranged. Fourth
The figure shows two rows of defining water pipes (4), and more than that may be provided. FIG. 5 shows a gas flow path (arrow) in place.

FIG. 6 is a diagram showing the relationship between the pitch (P) between the heat collecting water pipes in the vertical cylindrical inner can of the present invention and the diameter (S) of the heat collecting water pipes. In the present invention, P / It is preferable to set S to about 1.1 or more.

FIG. 7 is a view showing the relationship between the space (11) in the vertical cylindrical inner can of the present invention and the diameter (D) of the burner head, and as described above, the shortest distance (L from the burner head to the heat collecting water pipe). )
The relationship between and (D) is preferably L / D ≧ 1.

Further, FIG. 8 shows the distribution of the heat transfer surface heat load around the heat collecting water pipe in the vertical cylindrical inner can combustion chamber of the present invention. As described above, the total heat transfer surface heat load (Qr + Qc) [here Qr indicates radiative heat transfer and Qc indicates convective heat transfer.] Indicates that the heat transfer is almost uniform over the entire circumference of the heat collecting water pipe below the critical heat transfer surface heat load.

〔The invention's effect〕

 The effects of the present invention are summarized as follows.

(I) The present invention is an improvement of the conventional vertical boiler, in which a vertical cylindrical outer can which is closed at the upper and lower sides and a vertical cylindrical inner can which is partially opened at the upper and lower sides are inserted into the cylindrical inner can. Has a structure in which the defining water pipes for defining the combustion chamber side and the downstream side water pipe group are erected on the left and right, so the structure complexity and bulkiness, which are the drawbacks of the conventional vertical boiler, are eliminated. In addition, since many heat collecting water pipes are erected in the combustion chamber, the thermal efficiency is high and low.
There is an advantage that NOx can be achieved and the size of the boiler itself can be reduced in combination with the action of the defining water pipe.

(Ii) By setting the (L / D) to about 1 or more in the arrangement of the heat collecting water pipes in the combustion chamber, the burnout phenomenon of the heat collecting water pipes can be eliminated, and the heat collecting water pipes may be burned. Absent.

(Iii) By setting the ratio (P / S) of the gap (P) between the water pipes in the combustion chamber and the diameter (S) of the heat collecting water pipe to about 1.1 or more, the gas flow velocity around the heat collecting water pipe becomes faster. There is an advantage that there is no problem in combustion such that the pressure loss becomes large and the cross-sectional area perpendicular to the flow direction required for combustion cannot be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of one embodiment of the vertical boiler of the present invention, FIG. 2 is a vertical cross-sectional view of the same FIG. 1, FIG. 3, FIG. 4, and FIG. Fig. 6 is a longitudinal sectional view of an example, Fig. 6 is a view showing the relationship between the pitch between the heat collecting water pipes in the vertical cylindrical inner can of the present invention and the diameter of the heat collecting water pipe, and Fig. 7 is the vertical cylindrical inside of the present invention. Diagram showing the relationship between the space inside the can and the diameter of the burner head, No. 8
FIG. 9 is a diagram showing the distribution of heat load on the heat transfer surface around the heat collecting water pipe in the combustion chamber of the vertical cylindrical inner can according to the present invention, and FIG. 9 is a cross sectional view of a conventional boiler of Japanese Patent Laid-Open No. 62-242703. FIG. 10 shows a vertical sectional view of FIG. 1 ... Vertical cylindrical outer can, 2 ... Vertical cylindrical inner can, 3 ... Combustion chamber 4 ... Defining water pipe, 5b ... Standing cylindrical inner can combustion chamber heat collecting water pipe, 6 ... Burner, 7 ... Exhaust port, 8 ... Vertical fin 10 ... Gas passage, 11 ... Combustion chamber space 12 ... Burner head

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masamichi Yamamoto, 1-9-36, Oyodokita, Oyodo-ku, Osaka-shi, Osaka Prefecture (72) Inside Hirakawa Iron Works Co., Ltd. 1-9-36 Hirakawa Iron Works Co., Ltd. (72) Inventor Kiyoki Ishiya 8-7 Iwazono-cho, Ashiya-shi, Hyogo

Claims (3)

[Claims] 1. A vertical cylindrical inner can which is partially closed at the top and bottom is inserted into a vertical cylindrical outer can that is closed up and down, and a plurality of heat collections are made in the entire space of the combustion chamber in the vertical cylindrical inner can. A vertical boiler, wherein a water tube is provided or a space is provided by omitting only a part of the heat collecting water tube near the burner of the vertical boiler. 2. The vertical boiler according to claim 1, wherein the cylindrical inner can is provided with one or more rows of water pipes for defining the combustion chamber for inserting a heat collecting water pipe and the downstream side water pipe. 3. A pitch (P) for a heat collecting water pipe in an upright cylindrical inner can.
The vertical boiler according to claim 1 or 2, wherein the ratio (P / S) between the heat collecting water pipe and the diameter (S) of the heat collecting water pipe is about 1.1 or more.