JP3333826B2 - Boiler with water tube group - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a boiler in which a heat transfer surface is constituted by a large number of water tubes, and more particularly to a high-performance boiler having a water tube group by remarkably reducing the combustion chamber of the boiler.

[0002]

2. Description of the Related Art Conventionally, when a heat transfer surface is formed by a large number of water tubes, the purpose of improving the structure and improving the structure is mainly as described in Japanese Patent Application Laid-Open No. 2-178502 of the applicant of the present invention. 1) Improvement of the heat transfer coefficient of a large number of water pipe groups, (2) Maximization of heat absorption per unit volume, and (3) Minimization of ventilation loss of the large number of water pipe groups.

The above-mentioned invention of the applicant of the present invention is described in (1) to
In order to achieve (3), the arrangement of the water pipe group may be a chidling arrangement or a ragged arrangement, and the vertical and horizontal pitches and pipe diameters of the water pipe group are compared in relation to the Re number (Reynold's number) and selected. It has been.

[0004]

In the invention of Japanese Patent Application Laid-Open No. 2-178502 filed by the present applicant, the pitch in the gas flow direction (Lmm) and the pitch in the direction perpendicular to the gas flow in the water pipe group (Hmm) are described. It was confirmed that depending on the method of selecting the outer diameter (Dmm) of the water pipe, the rubbish arrangement was excellent. Subsequently, subsequent studies by the present inventors in order to dramatically increase the effects of the above-mentioned prior invention have revealed that there are various problems to be further studied in connection with the above-mentioned prior invention.

In general, in a boiler having a large number of water tubes as components, a water tube boiler is usually used when a majority of the heat transfer surface of the boiler is a water tube, but a part of the water tube is used. In such a case, for example, it is commonly called a round boiler or a vertical boiler. In the present invention, irrespective of the common name of the boiler, generally, when a large number of water pipes are used as components of the boiler, they all fall into the category of the boiler having the water pipe group of the present invention.

[0006] The above-mentioned prior art was to solve the problem on the heat receiving side under the condition of the heating side, that is, the concept that the flame of the heating side medium flows into the water pipe group with uniform flow and temperature. If the configuration of the water tube group changes, the distribution of the flow and temperature of the medium on the heating side naturally changes greatly. This has been found to be significantly related to the heat transfer of the medium. For example, the distribution of the velocity and temperature of the flow of the heated flame before entering the tube group in the combustion chamber is not uniform, and if there is a certain distribution, the distribution depends on the configuration of the tube group. It is increasingly amplified and biased. This is not preferable for improving the performance of the water pipe group in the combustion chamber. By way of further example, in a rubbish arrangement, the arrangement causes a rectification effect on the flow of flame and air, so that the mixing in the combustion chamber in the transverse direction is less likely to take place. In such a case, the staggered arrangement has a stronger mixing effect in the oblique direction, and is more easily uniformed in the wake, resulting in higher performance. Furthermore, the flame from the burner is not uniform. Generally, the flame of a burner formed in a combustion chamber is divided into a divergent type and a divergent type depending on the method of flame holding.

For example, a flame corresponding to the concept of parallel flow,
That is, it is practically impossible to make a flame flow having a uniform flow velocity and temperature distribution in a cross section of the combustion chamber in a parallel direction in the combustion chamber. In addition, the flow and temperature distribution generally have considerable uniformity in the circumferential direction (concentric with the flow or symmetric with respect to the burner axis). This is the same in the case of the prior invention of the present applicant, Japanese Patent Application Laid-Open No. 2-272207, in the case of a combustion chamber inserted into a heat collecting water pipe, so-called tube nest combustion.

[0008] For example, depending on the type of burner, the distribution of the temperature and the accompanying flow as described below are generated, and this greatly affects the distribution of heat transfer in each part of the water tube group.
Here, a gas fuel and a burner for burning the fuel will be described. In the burner type, a premixed burner in which fuel gas and air are already mixed, fuel gas and its combustion air are separately injected from the burner outlet into the combustion chamber upstream of the burner fuel outlet. There is a diffusion burner (or premix burner) that burns while diffusing and mixing the gas and air in the combustion chamber. The flame generated by the premix burner has a combustion rate of almost 100% (FIG. 13) near the outlet of the injection port (1) as shown in FIG. Therefore, the temperature is the highest, the flame is short, but high NOx is generated in the area, and in the wake, the gas temperature is rapidly reduced by radiant heat transfer and contact heat transfer.

The distribution of the air ratio (FIG. 12) at the burner outlet, which is the subject of the present invention, is substantially uniform. The reason is that the premixing burner is configured to mix uniformly under the burner, the flame at the burner outlet is short, and the air ratio at the tip of the flame (where the combustion rate is 100% at the end of combustion). It can be seen that both the gas temperature and the gas and air flows are substantially uniform. However, this type of burner is difficult to increase its capacity in principle due to safety issues, and is used only for small-capacity boilers, and is not practical as a medium- or large-capacity burner. On the other hand, the burner (FIG. 14) is a diffusion burner (premix burner), this type of burner is suitable mainly for large capacity for safety reasons, and in fact all medium and large capacity burners are of this type.

[0010] It has been found that the following problem arises when this type of burner is burned in a so-called heat-collecting water tube insertion type combustion chamber in which a burner is burned in a group of water tubes as shown in Fig. 14 for example. That is, as shown in FIG. 15, the distribution of the air ratio is seen in the direction perpendicular to the flow of the combustion chamber, and the flame is caused to proceed simultaneously with the combustion and the cooling by the water pipe group, so that the combustion rate in the combustion water pipe group is reduced. The temperature gradually increases to 100% with the progress, and the flame temperature is suppressed to a substantially constant low temperature from the beginning in the interaction between combustion and cooling, so that NOx is hardly generated, and CO and unburned HC (hydrocarbon) are completely eliminated. Combustion and heat transfer are obtained, as shown in FIG. 15. As shown in FIG. 15, there is a distribution of the air ratio in the radial direction from the burner center toward the outer periphery, and accordingly the distribution of the flame temperature also varies. It turned out to be. This is particularly remarkable in a random arrangement as shown in FIG. That is, the first flow is rectified and flows as it is in the Gomoku arrangement,
This is because it is difficult for the flow to be mixed in a direction perpendicular to the flow, and this has been found to be a drawback of the random arrangement.

In order to solve the above-mentioned drawbacks, it is one way to design the burner so that it is uniform in design. Therefore, as described above, the flame is divided into a divergent type and a divergent type, and in each case, the distribution of the air ratio ε changes in the radial direction. It turned out to be. That is, if there is a distribution in the air ratio and it continues to the boiler outlet,
There is a disadvantage that the exhaust gas loss increases because ₂ % cannot be reduced.

[0012]

SUMMARY OF THE INVENTION A first aspect of the present invention is to provide a water pipe group facing a burner flame outlet in a combustion chamber of a boiler having a large number of water pipes as heat transfer surfaces. If the flame is of a divergent type, a boiler having a water pipe group is characterized in that the water pipe in the combustion chamber close to the burner flame outlet is removed and the water pipe group is disposed.
In the arrangement of water pipes facing the burner flame outlet in the combustion chamber of a boiler having a large number of water pipes as heat transfer surfaces, if the flame from the burner flame outlet is narrow, the burner flame A boiler having a group of water tubes, wherein a group of water tubes is disposed in the combustion chamber by removing the water tubes in the periphery of the combustion chamber near the outlet, and the third is a boiler having a large number of water tubes as heat transfer surfaces. In the arrangement of the water pipe group facing the burner flame outlet in the combustion chamber of the boiler, whether the arrangement of the water pipe group facing the burner flame outlet is the first row and the second row in a zigzag arrangement, Alternatively, the first to fourth rows of the water pipe groups are arranged in a zigzag arrangement to arrange water pipe groups in the combustion chamber, and the water pipe groups downstream of those water pipe groups are arranged in a ragged arrangement. The fourth is a boiler having a group, and the fourth is the boiler fuel with a large number of water pipes as heat transfer surfaces. In arrangement of the water tube group facing the spout of the burner flame in the chamber, for the divergent type of flame,
The arrangement of the first and second rows in the combustion chamber is shifted to the outside, and the pitch between the water pipe groups is widened to form a rough arrangement of the water pipe groups. Fifth, a boiler having a water tube group characterized by having a ruby arrangement is described. Fifth, in a boiler having a large number of water tubes as heat transfer surfaces, the temperature of a flame from a burner outlet is 1000 to 1000.
A heat insulating space free of water pipe groups is provided by removing one or two rows of water pipe groups between 1200 ° C. or up to the outlet of the combustion chamber downstream of the flame. The present invention relates to a boiler having a water tube group.

In general, when a premixed burner (FIG. 14) has an air ratio distribution of ε ₁ , ε ₂ , ε ₃ , ε ₄ in the radial direction, depending on the flame holding method of the premixed burner, (Fig. 1)
And a divergent type as shown in FIG. In addition, in each case, there is a disadvantage that an air ratio distribution occurs in the wake and the exhaust gas O ₂ concentration cannot be finally reduced. In that case, as described above, the applicant's prior application invention,
As described in Japanese Patent No. 178502, in the case of heat transfer, the arrangement of the water tubes is superior, but if the distribution of the air ratio is first in the arrangement, the mixing of the flame in the subsequent flow proceeds. As a result, it has been found that the combustion air is wastefully bypassed and discharged without partially contributing to the combustion.

[0014]

[0015]

Next, the present invention will be described by way of examples. As shown in FIG. 3, in the water pipe group facing the burner outlet, in the divergent flame, the water pipe at the center is removed, and the surrounding flames are concentrated at the center to facilitate mixing. On the other hand, as shown in FIG. 4, in the case of a narrow flame, the water pipe on the outer periphery is removed to promote mixing from the center to the outer periphery. However, in this case, when it is expected that the water pipes in the front row will be overheated, a method such as taking into account the design of the water pipes is adopted.

FIG. 5 shows an embodiment in which the first to fourth rows of the tube group facing the burner outlet or the flame inlet are arranged in a zigzag arrangement, and the subsequent flow is arranged in a ragged arrangement. Yes,
(FIG. 6) and (FIG. 7) each show an embodiment as a modification of (FIG. 5), in which the pitch is reduced or the pitch is expanded outward in the same arrangement of the water pipes. . By blocking, the mainstream of the flow is interrupted,
It promotes mixing perpendicular to the flow. That is, in FIG. 6, the first column and the second column are arranged in a staggered manner, a resistance is given to the first flow, a rectifying effect is given at the beginning, and the initial condition of the air-fuel ratio of flame formation is made uniform. Alternatively, consideration was made to promote uniform diffusion by promoting the diffusion and mixing of the flame in the transverse direction. Also, in FIG. 7, the arrangement of the first row of the water pipe group, which is a coarsely arranged pattern, is designed so that the water pipes are moved outward to expand the pitch of the water pipes with respect to the formation of a divergent flame. This has the effect of making the air-fuel ratio bias more uniform.

[0017]

Further, FIG. 9, FIG. 10, and FIG. 11 show an embodiment in which water pipes in a combustion chamber or a boiler are arranged in a cross-girder shape. The first to face
In the third to third rows or the first to fourth rows, the water tube groups are arranged in a zigzag arrangement. That is, conventionally, a girder water pipe (3) shown in FIG.
Although a) and (3b) were all arranged in a ragged arrangement,
In the present invention, as shown in FIG. 9 and FIG. 11, the first to third columns to the first to fourth columns are arranged in a staggered manner, and are arranged to be shifted by a half pitch.

[0019]

The effects of the present invention are summarized as follows. According to the present invention, a large number of water pipes are arranged in a combustion chamber of a boiler or in a boiler, and mixing and diffusion are promoted by the large number of water pipe groups to make uniform a radial temperature distribution and an air ratio of a burner flame. It became possible. By removing the water pipe in the center near the burner outlet for the burner spout flame and the peripheral water pipe for the convergent burner, the mixing and diffusion of the flame in the radial direction are promoted. The performance of the combustion chamber is remarkably reduced, the performance of the water tube group is improved, and the uniformity of the air ratio of the flame and the temperature of the combustion gas is improved.

[Brief description of the drawings]

FIG. 1 is a model diagram of an embodiment of a tapered burner.

FIG. 2 is a model diagram of an embodiment of a Suehiro type burner.

FIG. 3 shows an embodiment in which the water pipe at the center of the Suehiro-type flame is removed so that the surrounding flames are concentrated at the center and mixed easily.

FIG. 4 shows an embodiment in which a water pipe on the outer periphery of a narrow flame is deleted to promote the mixing of the flame from the center to the outer periphery.

FIG. 5 shows an embodiment in which two to four rows of tube groups facing the burner outlet or the flame inlet are arranged in a zigzag arrangement, and the subsequent flow is arranged in a ragged arrangement.

FIG. 6 shows another embodiment as a modification of FIG.

FIG. 7 shows another embodiment as a modification of FIG.

FIG. 8 shows another embodiment as a modification of FIG.

FIG. 9 shows an embodiment of the present invention in which water pipes in a combustion chamber or a boiler are arranged in a grid.

FIG. 10 is a cross-sectional view of FIG. 9 in which water pipes in a combustion chamber or a boiler are arranged in a crossbeam.

FIG. 11 shows another embodiment of the present invention in which water pipes in a combustion chamber or a boiler are arranged in a grid.

FIG. 12 is a conceptual diagram of a conventional mixed combustion showing a conventional flame and water pipe group.

FIG. 13 shows the distance from the burner and the combustion rate in FIG.
The figure which shows the relationship with gas temperature.

FIG. 14 is a conceptual diagram of combustion of a conventional premix burner.

FIG. 15 shows the distance from the burner and the combustion rate in FIG.
The figure which shows the relationship with gas temperature.

[Explanation of symbols]

 1. Burner 2,3. Water pipe 4. Flame 5. Fuel 6. air

Continuing from the front page Judge, Kiyoshihisa Otsuki Judge, Shizuo Takimoto Judge, Shigeo Inoue (56) References JP-A-2-272207 (JP, A) JP-A-2-178502 (JP, A) JP-A-60- 78247 (JP, A)

Claims (3)

(57) [Claims] An arrangement of water tubes arranged in a flame of a combustion chamber of a boiler having a plurality of water tubes as a heat transfer surface and facing a discharge port of the burner flame in a combustion chamber of the boiler. Is a divergent type, among the water pipes arranged from the burner flame outlet to the peripheral part, the water pipes in the combustion chamber arranged near the spray outlet promote mixing in the direction perpendicular to the flow. Boiler having a water tube group, wherein the water tube group is disposed 2. A method of disposing a group of water pipes provided in a flame of a combustion chamber in a combustion chamber of a boiler having a plurality of water pipes as heat transfer surfaces, wherein the group of water pipes is provided in a flame of the combustion chamber. In the case of a tapered type, of the water pipes provided from the burner flame outlet to the peripheral portion, the water pipes in the peripheral portion of the combustion chamber provided near the spray outlet are mixed at right angles to the flow. A boiler having a water tube group, wherein the water tube group is disposed so as to be removed so as to be promoted. 3. The arrangement of water pipes provided in a flame of a combustion chamber in a combustion chamber of a boiler having a large number of water pipes as heat transfer surfaces and facing a discharge port of a burner flame. A boiler having a water tube group, wherein the first several stages of the water tube group are arranged in a zigzag arrangement and the second stage is arranged in a ragged arrangement.