JPH07119903A - Smoke tube boiler - Google Patents

Abstract

PURPOSE:To reduce exhaust concentration of nitrogen oxide by annularly forming a flame of a burner disposed oppositely to an inlet opening of a smoke tube along the inner wall surface of the tube. CONSTITUTION:A boiler casing 8 has an outer cylinder 11, tube plates 12, 13 and many smoke tubes 1 disposed between the plates 12 and 13. Burners 2 are respectively disposed in inlet openings of the tubes 1 oppositely to the openings. A structure of the burner 2 may be so formed of one turner that a burning surface of the burner to be formed with a flame is so divided and disposed as to be opposed to the openings of the tubes 1. The flame 3 of the burner 2 is annularly formed along the inner wall surface of the tube 1. The flame 3 is cooled by contact with the inner wall surface of the tube 1, and hence a flame temperature is lowered to suppress generation of thermal NOX.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for realizing low NOx in a smoke tube boiler.

[0002]

2. Description of the Related Art Conventionally, a smoke tube boiler having a structure in which a large number of smoke tubes are arranged on the body of the boiler has been used. This smoke tube boiler is configured to flow combustion gas into the smoke tube to heat water around the smoke tube.

In recent years, environmental issues have become more and more important, and regulations regarding the concentration of nitrogen oxides (NOx) in exhaust gas have become stricter. In the above-mentioned smoke tube boiler, a high temperature region (about 1800 ° C.) is formed on the central axis of the burner immediately downstream of the combustion start surface of the burner, and thermal NOx is generated. Measures for reducing this thermal NOx The current situation is that this has not been fully done.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the emission concentration of nitrogen oxide (NOx) in a smoke tube boiler.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a structure in which at least one smoke pipe is provided, and a burner is arranged so as to face an inlet opening of the smoke pipe. In the boiler, the flame of the burner,
It is characterized in that it is formed in an annular shape along the inner wall surface of the smoke pipe. Further, according to the present invention, in the smoke tube boiler having the above structure, the axial wall shape of the smoke tube is formed into a corrugated shape over a predetermined length from the inlet portion, and the inner wall surface of the smoke tube is projected inward. It is characterized by that.

[0006]

Since the flame of the burner is formed in an annular shape along the inner wall surface of the smoke pipe, the flame comes into contact with the inner wall surface of the smoke pipe to be cooled, and the flame temperature is lowered accordingly, so that the generation of thermal NOx is suppressed. It By making the axial wall shape of the smoke pipe a corrugated shape over a predetermined length from the inlet, and projecting the inner wall surface of the smoke pipe inward, the contact area between the flame and the inner wall surface of the smoke pipe increases, An even greater effect is obtained in terms of flame cooling and heat transfer to the flue.

[0007]

The preferred embodiments of the present invention will be described below. 1 and 2 show an embodiment of a smoke tube boiler to which the present invention is applied. This smoke tube boiler has a mixed gas cylinder (6),
It is configured by connecting a combustion tube (7), a can body (8) and a chimney base (9). The mixed gas cylinder (6) is supplied with a premixed gas in which the fuel gas and the combustion air are mixed in advance from the upstream side. The can body (8) includes an outer cylinder (11), tube plates (12) and (13), and a large number of smoke tubes (1) arranged between these tube plates (12) and (13). have. A liquid storage space (14) is formed between the outside of the smoke pipe (1) and the inside of the outer cylinder (11). The outer cylinder
(11) has a water inlet (1) for supplying water to the liquid storage space (14).
5) and a hot water outlet (16) for supplying hot water from the liquid storage space (14) to the outside.

Burners (2) are arranged at the inlet openings of the smoke pipe (1) so as to face the respective inlet openings.
The structure of this burner (2) consists of one burner, and the burner combustion surface where the flame is formed is divided and arranged so as to face each inlet opening of the smoke tube (1). You can also do it.

As shown in FIGS. 3 and 4, the flame (3) of the burner (2) is formed in an annular shape along the inner wall surface of the smoke tube (1). The flame (3) comes into contact with the inner wall surface of the smoke pipe (1) and is cooled, and the flame temperature is lowered accordingly, so that the generation of thermal NOx is suppressed. Desirably, reducing the flame temperature to 1500 ° C. or lower is more effective in suppressing the generation of thermal NOx.

As a concrete means for forming the flame of the burner in an annular shape along the inner wall surface of the smoke tube, a closing plate (4) is provided at the center of the premixed gas ejection surface of the burner (2). The central premixed gas ejection port is closed and an annular premixed gas ejection port is formed around it. In addition, a burner whose premixed gas ejection port is designed to have an annular shape in advance may be used.

The operation of the above structure will be described. First, the premixed gas supplied to the mixed gas cylinder (6) is ejected from the burner (2), and a flame is introduced into the inlet opening of each smoke pipe (1).
(3) is formed. Since this flame (3) is formed in an annular shape along the inner wall surface of the smoke pipe (1), it comes into contact with the inner wall surface of the smoke pipe and is cooled, and the flame temperature decreases accordingly, and the generation of thermal NOx is suppressed. To be done. High-temperature combustion gas (including combustion flame and gas undergoing combustion reaction) generated by the combustion of the burner then flows through the smoke pipe and is discharged to the outside of the system through the chimney table (9). During this time, the water flowing in from the water inlet (15) is heated by heat transfer from the smoke pipe in the liquid storage space (14) to become warm water, and then is supplied to the outside from the hot water outlet (16).

FIG. 5 shows another embodiment of the main part of FIG. In the embodiment shown in the figure, the shape of the pipe wall in the axial direction of the smoke pipe (1) is formed into a corrugated shape over a predetermined length from the inlet portion, and the inner wall surface of the smoke pipe is projected inward. Has become. With such a structure, the contact area between the flame and the inner wall surface of the smoke tube increases, and a greater effect can be obtained with respect to the cooling of the flame and the heat transfer to the smoke tube.

In the above description, the smoke tube boiler according to the present invention is described as a boiler for producing hot water.
By providing a vapor chamber above the liquid storage space (14),
It can also be used as a steam generation boiler.

[0014]

The present invention has the above-mentioned structure.
Since the flame of the burner is formed in an annular shape along the inner wall surface of the smoke pipe, the flame comes into contact with the inner wall surface of the smoke pipe to be cooled, and the flame temperature is lowered accordingly, effectively suppressing the generation of thermal NOx. be able to. Also, the axial wall shape of the smoke tube is corrugated over a predetermined length from the inlet,
By making the inner wall surface of the smoke tube project inward, the contact area between the flame and the inner wall surface of the smoke tube is increased, and it is possible to obtain a greater effect on the cooling of the flame and the heat transfer to the smoke tube. .

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a smoke tube boiler according to the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II in FIG.

FIG. 3 is a longitudinal sectional view showing an enlarged main part of FIG.

4 is a sectional view taken along line IV-IV in FIG.

5 is a vertical cross-sectional view showing, in an enlarged manner, another embodiment of the main part of FIG. 1. FIG.

[Explanation of symbols]

 1 smoke pipe 2 burner 3 flame

Claims (2)

[Claims] 1. A smoke tube boiler having at least one smoke tube (1), and a burner (2) arranged so as to face an inlet opening of the smoke tube, wherein a flame (3) of the burner (2) is ,
A smoke tube boiler characterized by being formed in an annular shape along the inner wall surface of the smoke tube (1). 2. The smoke tube boiler according to claim 1, wherein
A smoke tube boiler, characterized in that the smoke tube (1) has an axial tube wall shape that is corrugated over a predetermined length from an inlet portion, and an inner wall surface of the smoke tube is projected inward.