JPH086904B2 - Low NOx combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a low NOx combustion device that reduces nitrogen oxides (hereinafter referred to as NOx).

(Conventional Technology and Problems) Conventionally, a method of recirculating exhaust gas (hereinafter referred to as EGR) is known as one of methods for reducing NOx. (See, for example, Japanese Examined Patent Publication No. 57-54681) However, this kind of EGR type combustion device has a problem that it requires a recirculation passage for exhaust gas, which makes the device complicated and expensive.

An object of the present invention is to provide a low NOx combustion device that improves the above-mentioned problems, does not require a recirculation passage with a simple configuration, and can obtain a NOx reduction effect close to that of a conventional EGR type combustion device. .

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention uses an upper combustion pipe and a lower combustion pipe in which a plurality of combustion pipes whose upper surfaces are flame holes are alternately arranged vertically. A device is formed, narrowed portions projecting outward on both sides of the upper combustion pipe, the passage between the adjacent upper combustion pipes is narrowed, and the lower combustion pipe is arranged substantially in the center of this passage.

(Operation) The combustion gas in the lower combustion pipe and the secondary air have a narrow passage in the throttle portion of the upper combustion pipe, so that the combustion gas and the secondary air are mixed well and the passage is accelerated by the throttle action. Can pass through the high temperature region of the flame quickly, NOx
Can be reduced.

Further, since the combustion pipes are arranged above and below, a part of the exhaust gas of the lower combustion pipe acts on the flame of the upper combustion pipe, resulting in low oxygen combustion to lower the flame temperature and produce a NOx reduction effect. Combined with the NOx reduction effect due to the throttling action described above, overall low N
Can be Ox.

(Embodiment) FIG. 1 is a cross-sectional view of an essential part showing an embodiment of the present invention.
(1) is an upper combustion pipe, (2) is a lower combustion pipe, the upper surfaces of which are both flame holes (3) and (4), and a plurality of upper combustion pipes (1) and lower combustion pipes (2) are provided. Combustion devices are formed by alternately arranging them vertically.

The upper combustion pipe (1) and the lower combustion pipe (2) are provided with pressure reducing walls (5) and (6) for forming flames on both sides,
The pressure reducing walls (5) and (6) are provided with throttle portions (7) and (8) by projecting a part thereof to the outside, and the throttle portions (7) of the pressure reducing wall (5) of the upper combustion pipe (1). Is a passageway (9) between the pressure reducing wall (5) of the upper combustion pipe (1) adjacent to the throttle portion (7).
And the flow velocity of the combustion gas and the secondary air in the lower combustion pipe (2) passing through the passage (9) is increased.

In addition, as shown in FIG. 2, the passage (9) is narrowed so that the upper end of the pressure reducing wall (10) is bent outward and protrudes to form a narrowed portion (11) to form an adjacent pressure reducing wall (10). The passage (12) between the narrowed portion (11) and the narrowed portion (11) may be narrowed.
Alternatively, as shown in FIG. 3, the lower end of the pressure reducing wall (13) may be bent outward to form the throttle portion (14).

Further, as shown in FIG. 4, the side surface of the main body of the combustion pipe (15) may be projected outward to form the throttle portion (16), or other parts may be attached to the combustion pipe or the pressure reducing wall. You may attach to a side surface and may form a throttle part.

In short, the passage formed between the upper combustion pipe and the adjacent upper combustion pipe may be narrowed, and the narrowed portion may accelerate the flow of the combustion gas in the lower combustion pipe.

According to the present invention, due to the above configuration, the mixing of the combustion gas in the lower combustion pipe (2) with the secondary air is improved and the throttle action by the throttle portion (7) accelerates in the passage (9) to increase the flame temperature range. Since it passes through quickly, it reduces the generation of NOx.

Also, a part of the exhaust gas of the lower combustion pipe (2) acts on the flame of the upper combustion pipe, resulting in low oxygen combustion and lowering the flame temperature.
It produces a NOx reduction effect.

(Effects of the Invention) As described above, the present invention can further reduce the generation of NOx because the combustion products passing through the passage are further accelerated by the throttle action of the throttle portion and leave the high temperature region of the flame quickly. Along with this, since the combustion tubes are alternately arranged on the upper and lower sides, the exhaust gas of the lower combustion tube is mixed with the flame of the upper combustion tube, resulting in low oxygen combustion and lowering the flame temperature to reduce NOx generation, NOx can be greatly reduced with a simple structure as a whole.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention, FIGS. 2 and 3 are sectional views of an essential part showing another embodiment of a throttle portion of a pressure reducing wall, and FIG. It is a principal part sectional view which shows the Example which formed the narrowed part. (1) …… Upper combustion tube (2) …… Lower combustion tube (5) …… Decompression wall (7) …… Throttle section (9) …… Passage

Continuation of the front page (72) Inventor Tomohiko Shirotani 32 Akashi-cho, Chuo-ku, Kobe-shi, Hyogo Noritsu Co., Ltd. Inspector Yasushi Ohashi (56) Reference JP-A-3-263505 (JP, A)

Claims (1)

[Claims] 1. A combustion device is formed by an upper combustion pipe and a lower combustion pipe in which a plurality of combustion pipes whose upper surface is a flame hole surface are alternately arranged in parallel in the vertical direction, and a combustion device is formed so as to project outward on both sides of the upper combustion pipe. A narrowed portion is provided to narrow the passage between the adjacent upper combustion pipes,
A low NOx combustion device characterized in that a lower combustion pipe is arranged approximately in the center of this passage.