JPH0781682B2 - Water tube boiler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention aims to increase the heat transfer efficiency of a boiler and further reduce the volume of a boiler furnace by providing a heat collecting water pipe in the reactor tube. Achieves smaller and lighter boiler, NOx
The present invention relates to a water tube boiler for a reactor tube that can suppress the generation of

[Conventional technology]

As shown in FIGS. 9 and 10, the conventional fire tube smoke tube boiler has a structure in which after burning fuel in the fire tube inner space, the combustion gas is discharged to the outside through the fire tube. The required space for the furnace barrel occupies a large area, and therefore the boiler body was significantly large.

In addition, the prior inventions by the applicant of the present invention are JP-A-60-205105 and JP-A-5-205105.
Some boilers, such as 9-35703, have a water pipe inside the furnace tube, but all of them have a design that ensures the combustion space necessary for combustion, and this space is usually the large size of the entire boiler. Occupy a part. Therefore, the entire boiler was upsized.

[Problems to be Solved by the Invention]

In the conventional flue tube and water tube boiler, the flue tube and the water tube are designed to surround the combustion flame from the outside, and a combustion space matching the flame shape is secured. This required space volume is determined by the heat load on the combustion surface and heat transfer surface, but in the small and medium capacity boiler, the burner performance, that is, the shape of the flame is the decisive factor, and therefore a large space is required. When fuel is burned in such a large space, a high temperature part is formed in the central part of the flame, which increases the amount of NOx produced and may cause pollution problems.

An object of the present invention is to increase the efficiency of the boiler, reduce the size of the boiler, and suppress the generation of NOx by disposing a large number of heat collecting water pipes in the reactor tube.

[Means for Solving the Problems]

The present invention is a furnace tube water tube boiler, wherein a plurality of heat collecting water tubes are arranged in the entire space inside the furnace tube, or a space portion is created by omitting a part of the heat collecting water tube near the burner of the boiler. A cylinder water tube boiler is provided.

In the furnace tube of the conventional water tube boiler, it was not adopted under the idea that when a flame hits the water tube as in the present invention, unburned components are generated and the water tube burns. .

However, from the basic research results of the present inventors, etc. (a) When a flame hits the heat collecting water pipe arranged in the reactor tube, the flame is certainly cooled within 1 mm of the water pipe surface, and unburned components and C
Although O is generated, unburned components and CO are burnt and disappear in this part due to the spacing of several tens of mm between the water pipes.

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

(C) The heat collecting water pipes present in the flame receive almost uniform radiative heat transfer from the surroundings, but the effective amount of the radiant gas layer is remarkably small unlike the conventional large space combustion, so the amount of heat transfer is It was found that the contact heat transfer due to the gas flow was larger than the conventional type.

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 at which burnout does not occur. Almost uniform over the entire circumference of the heat collecting water pipe. . In the present invention, although it depends on the characteristics of the burner, for example, when a diffusion type premix burner is used, the diameter (D) of the burner head and the balance of the burner head from the burner head are kept so as not to impair the flame holding performance of the burner itself. The shortest distance to the hot water pipe is (L),
Stable combustion of the burner is achieved by setting L / D ≧ 1.

Further, in the present invention, in order to improve the contact heat transfer effect of the heat collecting water pipes in the reactor, it is necessary to make the flow velocity to some extent fast in the heat collecting water pipe group, but if it becomes too fast, the pressure loss becomes large and The ratio of the gap between the water pipes (P) and the diameter of the water pipe (S) P / S due to the increase in fan power and the inability to obtain a cross-sectional area perpendicular to the flow direction required for combustion, which causes problems in combustion. Should be about 1.1 or above.

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 in a staggered arrangement.

Due to the characteristics of the burner in the heat collecting water pipe in the reactor tube, a bare pipe is used for the high heat transfer surface heat load part, or a groove is provided on the inner surface of the heat collecting water pipe or an adiabatic coating is provided on the outer surface for low heat transfer. By providing fins on the outer surface of the surface heat load portion, it is effective for both prevention of fuel loss on the heat transfer surface and promotion of heat transfer.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of an embodiment of a water tube boiler of the present invention, and FIGS. 2 to 4 are vertical cross-sectional views of a boiler body of the present invention, showing different heat collecting water pipes in a reactor. Different arrangements are shown.

In Fig. 1, a large number of heat collecting water pipes (2b) are installed in the reactor tube (1).
Is provided, the flame emitted from the burner (8) undergoes combustion promotion and heat transfer when passing through the heat collecting water pipe, and is discharged to the outside through the smoke chamber (3).

Conventionally, the boiler was composed of the combustion space and the contact heat transfer part of the wake, but in this embodiment, since the combustion and heat transfer can be completed within the volume of the conventional combustion space, the boiler cylinder is half the size of the conventional boiler. It can be downsized. Furthermore, even with the same burner, NOx achieved a 50% suppression effect by cooling the flame with this heat collecting water pipe. Fig. 5 shows the relationship between the pitch of the heat collecting water pipes in the reactor and the diameter of the water pipe. The ratio P / S between the pitch (P) between the water pipes and the water pipe diameter (S) is set to about 1.8 or more. Yes, 6th
The figure is an example showing the relationship between the combustion chamber space (11) and the burner head (D) when a diffusion burner is used. L / D at the shortest distance (L) between the tip of the burner head and the heat collecting water pipe
Is 1.2. Further, as shown in FIG. 3 and FIG. 4, even if the furnace cylinder is rectangular, it may be inclined so that the heat collecting water pipes are alternately crossed.

〔The invention's effect〕

 The effects of the present invention can be summarized as follows.

(I) In the present invention, by providing a heat collecting water pipe in the furnace tube of the boiler, combustion promotion and high-performance heat transfer can be achieved, and the size can be reduced to about half of that of the conventional round boiler. The cost can be reduced and the installation space can be reduced.

(Ii) Due to the flame cooling effect of the heat collecting water pipe, it is possible to suppress NOx emissions by 50% even with the same burner.

(Iii) By setting the ratio P / S of the gap (P) between the heat collection water pipes in the reactor tube and the diameter (S) of the water pipes to about 1.1 or more, the gas flow velocity around the heat collection water pipes becomes too fast. There were no problems with combustion such as increased pressure loss.

(Iv) It is effective to prevent heat loss on the heat transfer surface and to promote heat transfer by using a heat-insulating water pipe, a heat-insulating pipe, a bare pipe, and a fincheube tube in combination.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a water tube boiler of the present invention,
FIG. 2 is a vertical cross-sectional view of an embodiment of a barrel portion of a water tube boiler according to the present invention, and FIGS. 3 and 4 are views showing an embodiment of a barrel portion of a water tube boiler having different furnace tube shapes. Fig. 5 is a vertical sectional view of an example, Fig. 5 is an embodiment showing the relationship between the distance between the heat collecting water pipes in the furnace and the diameter of the heat collecting water pipes, and Fig. 6 is a distance relationship between the space inside the combustion chamber in the furnace and the burner head. One embodiment, FIG. 7 is one embodiment showing the heat distribution of the heat collecting water pipe in the reactor, FIG. 8 is one embodiment showing the relationship between the flame in the reactor, the heat collecting water pipe and the smoke pipe, and FIG. FIG. 10 is a schematic cross-sectional view of a reactor water tube boiler, and FIG. 10 is a schematic vertical cross-sectional view of an example of a body portion of a conventional reactor water tube boiler. 1 ... Reactor tube, 2a ... Smoke tube, 2b ... Heat collecting water tube 4 ... Water surface, 5 ... Boiler barrel, 6 ... Exhaust gas 8 ... Boiler burner part, 9 ... Convective heat transfer 10 ... Radiative heat transfer , 11 …… Space section, 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. In a reactor tube water tube boiler, a plurality of heat collecting water pipes are arranged in the entire space inside the furnace tube, or a space is created by omitting a part of the heat collecting water pipe near the burner of the boiler. And a heat collecting water pipe is provided inside the furnace cylinder. 2. The ratio P / S of the gap (P) between the heat collecting water pipes in the furnace tube and the diameter (S) of the heat collecting water pipes is set to about 1.1 or more.
Described water tube boiler. 3. In a heat collecting water pipe in a furnace tube, a bare pipe is used for a high heat transfer surface heat load part, or a groove is provided on an inner surface of the heat collecting water pipe, or an outer surface is provided with a heat insulating coating, thereby lowering heat transfer. The reactor tube water tube boiler according to claim 1 or 2, wherein a fin is provided on an outer surface of the surface heat load portion.