JPS5935707A - Combustion device - Google Patents

Abstract

PURPOSE:To reduce NOx without increasing the smoke dust contained in waste gas by dividing an after air port into a primary air passage pipe at the central part and air passages for secondary or more passages provided successively on the outer periphery of the primary air passage and providing a tapered throttle at the tip end on the furnace side of the primary air passage pipe. CONSTITUTION:Air taken from a blast box 18 into a primary air passage pipe 17 through a primary air take-in port 10, is shaped the flow by a distributing plate 11 and thereafter is accelerated by the tapered nozzle 13, thus the air being injected in a high-speed and high-density state from the primary air passage pipe 12 to the central part of a furnace. Accordingly, sufficient supply of air becomes possible with respect to the central part of the furnace to which supply of air has heretofore been difficult, and complete combustion is satisfactorily achieved. On the other hand, air sent from the blast box 18 to a secondary air passage 15 is given with appropriate swirl by a secondary air resister 14 and the injecting port of the secondary air passage 15 is enlarged in the tip. On the above described causes, supply of air to the furnace wall surface becomes satisfactory, whereby a complete combustion becomes possible even on the furnace wall surface to which supply of air has been heretofore difficult.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion device, and in particular to a combustion device that eliminates nitrogen oxides (
The present invention relates to a boiler device suitable for reducing NO (hereinafter referred to as NO).

NOA is considered to be one of the causative substances of photochemical oxidants, and in recent years, there has been a demand for the development of a combustion method that effectively suppresses its generation. Combustion methods that meet these objectives include (1) exhaust gas recirculation method, (2) water injection method, and (3)
) Two-stage combustion method and (4) Denitrification combustion method are known, and among these, the two-stage combustion method is attracting particular attention because of its excellent NO reduction effect and drivability.

As shown in FIGS. 1 and 2, the device applied to the conventional two-stage combustion method includes a lower burner 3, a middle burner 4, and an upper burner, which are sequentially provided from the bottom to the top on the front side wall of the furnace 1. 5, a front after-air port 6 provided above the upper burner 5, a rear after-air port 7 provided on the rear wall of the furnace 1, and a hopper port 2 for exhaust gas adjustment provided at the bottom of the furnace 1. It is mainly composed of.

In the above configuration, the air ratio (actually supplied air acid/theoretically required air intake) in the burner section is usually 0.8 to 1.0 for the lower bar force 3 and 0.6 to 0 for the middle burner 4. ．．
8. The upper stage burner 5 is set to 0.4 to 0.6, and combustion is performed under such conditions.

In this case, NO, generated in the combustion region of the lower stage burner 3 and middle stage burner 4, where there is a relatively large amount of air, is generated in the combustion region of the upper stage burner 5, where there is an excess of fuel.
H2 and N2 in contact with reducing radicals such as I
will be returned to.

Although the two-stage combustion method has these advantages, the combustion gas contains a large amount of unburned matter, and it is not desirable to discharge it as it is from the viewpoint of preventing soot and dust and from the standpoint of thermal efficiency. By supplying air through the after air ports 6 and 7, complete combustion of unburned materials is achieved.

The heat generated by the above-mentioned combustion section is used, for example, as a heat source for evaporating boiler feed water, while the high-temperature exhaust gas passes through the flue at the top of the furnace 1 and is recovered by a heat exchanger (not shown) provided as necessary. It is then released into the atmosphere.

However, the air supply from the after-air port in the above-mentioned conventional combustion apparatus was carried out by a simple method such as simply blowing out air from an air passage pipe or in a swirling flow, and this had the following drawbacks. That is, if air is simply blown out, the air supply to the furnace wall becomes insufficient and complete combustion there becomes difficult. On the other hand, when air is ejected in a swirling flow, there is a disadvantage in that, contrary to the above, the air supply to the center of the furnace becomes insufficient, making complete combustion in the center of the furnace difficult. If such an incomplete combustion part occurs, soot and dust are likely to be generated as a result, but in order to avoid this, it is necessary to strengthen the combustion in the burner part, which results in an unfavorable result in terms of suppressing NO.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to eliminate NO without increasing soot and dust in exhaust gas.

The objective is to provide a combustion device that can reduce the

In order to achieve the above object, the present invention provides a combustion apparatus in which a plurality of burners are provided in multiple stages and an after air port is provided above the burners, in which the after air port is provided between the primary air passage pipe in the center and its outer periphery. The present invention is characterized in that it is divided into secondary and higher air passages which are sequentially provided, and that a tapered throttle is provided at the front end of the secondary air passage pipe on the furnace side.

In the present invention, by dividing the after-air port into a primary air passage pipe in the center and secondary and higher air passages sequentially provided on the outer periphery of the after-air port, the air supply to the center of the furnace is improved by the secondary air passage pipes. Furthermore, since air is suitably supplied to the furnace wall through the secondary and higher air passages, the occurrence of air-deficient areas within the furnace is eliminated, and uniform and complete combustion can be achieved. In addition, by providing a tapered throttle at the tip of the secondary air passage tube on the furnace side, the air sent through the secondary air passage tube is accelerated, and the air density in the jetting direction is improved, allowing it to reach the center of the furnace. air supply is carried out suitably.

In order to further improve the air density in the above-mentioned jetting direction, it is desirable to provide a rectifying plate in the secondary air passage pipe.A tapered throttle is usually installed in the axial direction of the secondary air passage pipe. It may be provided inclined (deflected) with respect to the axis. At this time, by connecting the secondary air passage pipe to an external drive means and making it rotatable, it is possible to set the direction of air ejection to a desired direction. In addition, in order to respond to changes in combustion conditions, it is desirable to provide an air flow rate adjustment mechanism for each air passage. Among the air flow rate regulating mechanisms, those provided in the secondary and higher air passages are preferably those capable of imparting an appropriate swirling flow to the air, such as an air register, since it is necessary to guide the ejected air to the furnace wall surface.

Hereinafter, the present invention will be explained in more detail with reference to embodiments shown in the drawings.

3 and 4 are enlarged views of the after air port portion of the present invention applied in place of the after air ports 6 and 7 of the device shown in FIGS. 1 and 2, which The primary air passage pipe 17 has a grid-like rectifier plate 11 in the pipe and a tapered throttle 13 at the tip end on the furnace side, and is provided in the center, and a primary air passage pipe 17 provided on the outer periphery of the secondary air passage pipe 17. It mainly consists of a secondary air passage 15. In addition, 18 is a wind box, and 9 is a wind box 18. When guiding the air sent from the wind box 18 to the primary air passage pipe 17 via the primary air intake 10, the opening degree of the sky air intake 10 is adjusted to control the intake air. The primary air damper 14 for controlling the amount of air can adjust the amount of air sent from the wind box 18 taken into the secondary air passage 15, and can also impart an appropriate swirling flow to the intake air. A secondary air register, 12 is a primary air outlet formed at the tip of a tapered throttle 13, and 8 is an inner wall of the furnace.

With the above configuration, the air taken from the wind box 18 through the primary air intake port 10 into the primary air passage pipe 17 is rectified by the rectifying plate 11, then accelerated by the tapered throttle 13, and -
The secondary air is ejected from the air outlet 12 at high speed and high density into the center of the furnace. As a result, sufficient air can be supplied to the center of the furnace, where it has been difficult to supply air in the past, and complete combustion can be achieved satisfactorily.

On the other hand, the air sent from the wind box 18 to the secondary air passage 15 is given an appropriate swirl by the secondary air register 14, and the ejection port of the secondary air passage 15 is shaped like a tip. As a result, the supply to the furnace wall is improved. This makes it possible to achieve complete combustion even on the furnace wall, where it has been difficult to supply air in the past.

As described above, according to the wood embodiment, air is uniformly supplied into the furnace, so there is no increase in soot and dust due to the formation of incomplete combustion parts, and therefore, the combustion in the burner part is reduced to NO.
It becomes possible to further incline to excessive fuel conditions that are advantageous for reduction, and it is possible to achieve even more excellent reduction in NOx.

Next, FIG. 5 shows a device according to another embodiment of the present invention, in which instead of the tapered throttle 13 shown in FIG. A tapered slanted aperture 16 is provided.

By adopting the above configuration, the influence of flame rise in the furnace can be reduced, so the ejection reach distance of secondary air is improved,
Accordingly, combustibility becomes better. Note that the air jetting direction of the tapered aperture 16 is not necessarily limited to the downward direction.

In order to apply a direction other than downward, the -next air passage pipe 1
7 can be freely rotated by an external drive means (not shown).
Bye ℃・.

Although the above explanation has been made with reference to typical embodiments of the present invention, the present invention is of course not intended to be limited to these embodiments, and may include various other aspects and deformation forces (existence). Needless to say, it can be applied in the same way to a combustion device with facing installation type in which each burner is installed on the rear side of the furnace. It is also possible to provide two or more stages facing the front and rear walls of the furnace, and the same effect can be obtained.

As described above, according to the present invention, the after-air port is divided into a primary air passage pipe and secondary and higher air passages sequentially provided on the outer periphery of the after-air port, and a tapered throttle is provided at the front end of the secondary air passage pipe on the furnace side. By providing this, it is possible to improve the air supply from the secondary air passage pipe to the center of the furnace, and from the secondary and higher air passages to the furnace wall surface. This makes it possible to completely burn the combustion gas containing unburned materials generated in the burner section.
As a result, NO! in the burner section! Not only can the combustion conditions for excess fuel, which are advantageous for reduction, be further advanced, but also so-called paper 02 combustion can be performed in which the amount of air supplied is suppressed as much as possible in the after-air port section, so the boiler efficiency is also improved.

[Brief explanation of the drawing]

Figure 1 is a side sectional view showing a conventional combustion device, and Figure 2 is a
FIG. 31 is a side sectional view of the after air port section according to the embodiment of the present invention; FIG. 4 is a cross section taken along line C-C in FIG. 3 in the direction of arrows. 5 are side sectional views of a portion corresponding to B in FIG. 3 of an after air port portion according to another embodiment of the present invention. 3...lower burner, 4...middle burner (-su, 5...
Upper row) (-su, 6...Front side after air port, 7...
・Rear afterair port, 9...-Next air dunnno (,
10...-sky air intake, 11... rectifier plate, 12...
...-Next air outlet, 13... Corpse narrow aperture, 14...
・Secondary air register, 15...Secondary air passage, 16・
・・Deflection tapered aperture, 17 ・・Next air passage pipe, 18
...Wind box. Agent Patent Attorney Takenaga KawakitaFigure 1Figure 3Figure 2Figure 4Figure 5Figure 1^8 Ki゛

Claims (1)

[Claims] (1) In a combustion device in which a plurality of burners are provided in multiple stages and after air ports are provided above them, the after air ports are sequentially provided in the primary air passage in the center and the outer periphery thereof. A combustion device characterized in that the secondary air passage is divided into secondary or higher air passages, and a tapered throttle is provided at the front end of the secondary air passage on the furnace side. (2. In claim 1, the combustion device is characterized in that each air passage is provided with an air flow adjustment mechanism corresponding to each air passage. (3) In claim 1, - A combustion device characterized in that a rectifying plate is provided in the secondary air passage. (4) 4? In claim 1, the tapered throttle has a deflection shape, and the secondary air passage is rotatable. A combustion device characterized by: