JP3365959B2 - Combustion space structure of boiler equipped with endothermic water pipe in combustion flame - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention achieves the size and weight reduction of a boiler by increasing the heat transfer efficiency of the boiler and further reducing the volume of the boiler furnace, thereby suppressing the generation of NOx. The present invention relates to a combustion space portion structure in a boiler provided with a combustion flame portion in which fuel burns and a heat collecting water pipe.

[0002]

2. Description of the Related Art A conventional flue tube boiler is shown in FIGS.
As shown in Fig. 4, after the fuel is burned in the inner space of the furnace, that is, after the combustion is completed, the combustion gas is discharged to the outside through the smoke tube. The required space was large, which made the boiler body extremely large.

Further, the invention of the prior application by the present applicant is disclosed in Japanese Patent Laid-Open No. 60-
There is a water tube boiler in which a water tube is arranged in the inner part of the furnace tube as in Japanese Patent No. 205105 and Japanese Patent Application Laid-Open No. 59-35703, but in each case, the combustion space portion (combustion chamber) required for combustion is the combustion. It is designed only for this purpose, and this space usually occupies most of the entire boiler. Therefore, the entire boiler was upsized.

[0004]

In the conventional furnace tube smoke tube and furnace tube water tube boiler, the furnace 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. . The required space volume is determined by the heat load on the combustion surface and the heat transfer surface, but in a small or medium capacity boiler, the burner performance, that is, the shape of the flame is the decisive factor, and a large space is required for that purpose. When fuel is burned in such a large space, a high temperature portion is formed in the center of the flame, and the high temperature portion increases the amount of NOx produced, which 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 arranging a large number of heat collecting water pipes in the combustion flame.

A large number of heat collecting water pipes are arranged in the entire space of the combustion chamber to arrange a large number of heat collecting water pipes in the combustion flame in which the fuel burns, or a part of the heat collecting water pipes near the burner is omitted. A large number of heat collecting water pipes are provided in the combustion flame in the entire space of the combustion chamber to perform a combustion promoting action and a heat collecting action, and the combustion is promoted by generating a vortex flow in the wake of the heat absorbing water pipe and burns in the combustion flame. (EN) Provided is a boiler combustion chamber structure that prevents outflow, removes the generation of harmful exhaust substances, and arranges a heat collecting water pipe in the combustion chamber to reduce the size.

In the conventional water tube boiler of a conventional reactor tube, if a combustion flame is struck against the water tube according to the present invention in the reactor tube, it is long considered that unburned components are produced and the water tube is burned. In the past, it was banned and adopted.

However, from the basic research results of the present inventors, (a) When a combustion flame is struck on the heat collecting water pipe arranged in the furnace tube, the flame is certainly cooled within 1 mm of the water pipe surface. Fuel CO is generated, but there are several tens of mm between the water pipes
The unburned component and CO burn and disappear in this part by taking the gap of.

(B) Comparing the case of the present invention having a heat collecting water pipe with the combustion in the large space of the conventional vertical boiler, the flow around the heat collecting water pipe by arranging the heat collecting water pipe, particularly,
Since there is a gap in which a vortex flow is generated and a vortex flow is generated in the wake of the water pipe, the distance (flame length) from the burner head to the disappearance of unburned components and CO is much shorter. At the same time, since the cold heat collecting water pipe is present, the flame is cooled and does not reach a high temperature, which greatly contributes to the suppression of NOx generation.

(C) The heat-collecting water pipes present in the flame receive a substantially uniform radiant heat transfer from the surroundings, but the effective thickness of the radiant gas layer is remarkably small unlike the conventional large space combustion. Therefore, it was found that the amount of heat transfer was smaller than that of the conventional type, and rather the contact heat transfer due to the gas flow was greater.

FIG. 8 shows the heat load distribution on the heat transfer surface around the heat collecting water pipe according to the present invention. In FIG. 8, (9) is convective heat transfer (Qc), (10) is radiant heat transfer (Qr), and total heat transfer surface heat load (Qc + Qr) is limit heat transfer surface heat that does not cause burnout or other burnout. Under the load, it 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 and the burner head are set so as not to impair the flame holding performance of the burner itself. Stable combustion of the burner is achieved by setting L / D ≧ 1 with (L) being the shortest distance from to the heat collecting water pipe in the furnace cylinder.

Further, in the present invention, in order to improve the contact heat transfer effect of the heat collecting water pipes, it is necessary to make the flow velocity of the heat collecting water pipes to some extent fast, but if it becomes too fast, pressure loss will occur. The pitch (P) between the water pipes increases because of the increase in combustion fan power and the cross-sectional area perpendicular to the flow direction required for combustion cannot be obtained, which causes a problem in combustion.
It is preferable that the diameter (S) of the water pipe is 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 in a staggered arrangement.

In the heat collecting water pipe, depending on the characteristics of the burner, a bare pipe is used for the high heat transfer surface heat load portion, a groove is provided on the inner surface of the heat collecting water pipe, or a heat insulating coating is formed on the outer surface. By providing fins on the outer surface of the low heat transfer surface heat load part,
It is effective for both the prevention of fuel loss on the heat transfer surface and the promotion of heat transfer.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to Examples shown in the drawings.

In FIG. 1, a reactor tube water tube boiler is shown, and a heat collecting water tube is arranged in the entire space in a furnace tube (1) which is a combustion chamber in which fuel burns, and a combustion action is performed in the tube. Since a large number of heat collecting water pipes (2b) are arranged in the combustion flame, the combustion flame emitted from the burner (8) promotes combustion when passing through the heat collecting water pipes (2b). Both the action and the heat transfer action are performed, and the exhaust gas (6) is discharged to the outside through the smoke chamber (3).

The conventional boiler is composed of the combustion space and the wake contact heat transfer part. However, in this embodiment, since the combustion and the heat transfer can be completed simultaneously within the volume of the conventional combustion space, the boiler cylinder Can be downsized to about half the size of conventional products. Further, even with the same burner for N0x, the combustion flame was cooled by the main heat collecting water pipe, so that the suppression effect of 50% was achieved.

FIG. 5 shows the relationship between the pitch of the heat collecting water pipes and the diameter of the water pipes. 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. By setting the pitch (P) of the heat collecting water pipes and the diameter (S) of the water pipes to about 1.1 or more in this way, the gas flow velocity around the heat collecting water pipes becomes too fast and the pressure loss is reduced. Combustion problems such as increasing size are eliminated.

FIG. 6 is an embodiment showing the relationship between the combustion chamber space (11) and the burner head (D) when a diffusion burner is used, and shows the relationship between the burner head (D) and the heat collecting water pipe. The hot water pipe is omitted and a space (11) for the combustion chamber is provided.

In FIG. 6, the 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 FIGS. 3 and 4, the reactor tube may be of a rectangular type, but it may be inclined so that the heat collecting water pipes are alternately crossed.

Further, in order to effectively prevent both heat loss on the heat transfer surface and promotion of heat transfer, an adiabatic coating tube, a bare tube, and a fin tube tube may be used in combination with the heat collecting water tube (not shown). ). In other words, depending on the characteristics of the burner, 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 outer surface is heat-insulated to form a low heat transfer surface heat load part. When fins are provided on the outer surface of the heat transfer surface, it is effective in terms of both preventing heat loss on the heat transfer surface and promoting heat transfer.

[0024]

The effects of the present invention are as follows. (I) The present invention achieves combustion promotion and high-performance heat transfer by providing a heat-collecting water pipe in a combustion flame, and can reduce the size of a conventional round boiler to about half. The cost can be reduced and the installation space can be reduced. (Ii) Due to the action of cooling the combustion flame by the heat collecting water pipe, it is possible to suppress NOx emission by 50% even with the same burner. (Iii) In the heat collecting water pipe, depending on the characteristics of the burner, use a bare pipe for the high heat transfer surface heat load part, or provide a groove on the inner surface of the heat collecting water pipe or perform heat insulation coating on the outer surface. By providing fins on the outer surface of the low heat transfer surface heat load portion, this is effective for both prevention of fuel loss on the heat transfer surface and promotion of heat transfer.

[Brief description of drawings]

FIG. 1 is a cross-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 the body portion of FIG.

FIG. 3 is a longitudinal sectional view of a body portion of another embodiment in which the shape of the furnace tube is different.

FIG. 4 is a longitudinal sectional view of a body portion of another embodiment in which the shape of the furnace cylinder is different.

[Fig. 5] Fig. 5 is an example showing the relationship between the distance between the heat collecting water pipes and the diameter of the heat collecting water pipes in the furnace.

FIG. 6 is an example showing a distance relationship between a combustion chamber space inside a furnace and a burner head.

FIG. 7 is a conceptual diagram showing a relationship between a heat collecting water pipe in a furnace and a combustion flame.

FIG. 8 shows a relationship between total heat transfer surface heat loads around a heat collecting water pipe due to a combustion flame in the present invention.

FIG. 9 is a schematic sectional view of a conventional flue tube boiler.

FIG. 10 is a schematic vertical cross-sectional view of a body portion of a conventional flue tube boiler.

[Explanation of symbols]

1 furnace barrel 2a smoke pipe 2b Heat collecting water pipe 4 water surface 5 boiler barrel 6 exhaust gas 8 Boiler burner part 9 Convective heat transfer 10 Width heat transfer 11 Combustion chamber space 12 burner head

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Atsumi Kaminashi 1-936 Oyodokita, Kita-ku, Osaka City, Osaka Prefecture Hirakawa Guy Dam Co., Ltd. (72) Inventor Masamichi Yamamoto Kita-ku, Osaka City, Osaka Prefecture Oyodokita 1-936 Hirakawa Guy Dam Co., Ltd. (72) Inventor Kara Kyoshira 1-936 Oyodokita 1-936 Oyodokita, Kita-ku, Osaka-shi, Osaka (72) Inventor Kiyoki Ishitani 8-7 Iwazono-cho, Ashiya-shi, Hyogo (56) References JP-A-60-205105 (JP, A) JP-A-60-78247 (JP, A) Jikken 39-1002 (JP, Y1) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) F22B 21/04 F22B 7/06

Claims (3)

(57) [Claims] 1. A large number of heat collecting water pipes are arranged in the entire space of a combustion chamber to arrange a large number of heat collecting water pipes in a combustion flame in which a fuel burns, or a part of the heat collecting water pipes near a burner is provided. A large number of heat collecting water pipes are provided in the combustion flame in the entire combustion chamber to perform combustion promoting action and heat collecting action, and the combustion is promoted by generating a vortex flow behind the heat absorbing water pipe, and also the combustion flame. The combustion chamber structure of the boiler is characterized in that it prevents burnout, removes harmful exhaust emissions, and arranges heat collecting water pipes in the combustion chamber to reduce the size. 2. The boiler combustion chamber structure according to claim 1, wherein the ratio P / S between the pitch (P) between the heat collecting water pipes and the diameter (S) of the heat collecting water pipes is set to about 1.1 or more. 3. A high heat transfer surface heat load part uses a bare pipe, or a groove is formed on the inner surface of the heat collecting water pipe or an outer surface is heat-insulated, and a low heat transfer surface heat load part is formed on the outer surface. The combustion chamber structure for a boiler according to claim 1, wherein a fin is provided.