JPH0423162B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a combustion device that achieves low NOx combustion through two-stage combustion.

BACKGROUND TECHNOLOGY As shown in FIG. 2, a conventional combustion device of this type includes a premixture chamber 1 in which a part of combustion air is premixed with gaseous fuel as primary air, and a A flame hole body 2 that is horizontally elongated and has a large number of flame holes provided, a primary combustion chamber 3 on the upper part of this flame hole body 2, and a peripheral wall of this primary combustion chamber 3 and the premixing chamber 1,
It consisted of a secondary air chamber 4 which is surrounded by a gap and which supplies combustion secondary air above the primary combustion chamber 3, and a rectifying plate provided above the primary combustion chamber 3. (For example, Japanese Unexamined Patent Publication No. 56-32524) Problems to be Solved by the Invention However, in the above configuration, an inner flame A corresponding to the amount of primary air is formed on the flame hole body 2. , the external flame depends on the amount of unburned gas and the amount of secondary air,
Since it is formed above the primary combustion chamber 3 or between the rectifying plates 5, the outer flame tends to become unstable in the transition state.
The problem was that combustion intermediate products were likely to be generated.

Means for Solving the Problems In order to solve the above problems, the combustion apparatus of the present invention includes a premix combustion burner having a primary flame hole, a secondary combustion burner housing the premix combustion burner, and a secondary combustion burner formed at one end. A first box body that is isolated from the atmosphere except for the flame hole, and is provided with a protrusion facing inward over the entire length in the longitudinal direction at a position below the secondary flame hole, and surrounding the first box body, It has openings at both ends, and the 2
A second box body is provided at a position above the second flame hole and has a protrusion extending inward over the entire length in the longitudinal direction.

Effects According to the present invention, with the above-described configuration, the primary flame hole of the premix combustion burner is completely surrounded by the first box body having the secondary flame hole, so that the secondary air is
It does not flow into the secondary flame hole, but diffuses and mixes with unburned gas on the secondary flame hole. Therefore, the inner flame C is formed on the primary flame hole, and the outer flame D is formed on the secondary flame hole. Moreover, since the secondary air flows in the direction of the central axis of the second box due to the protrusion of the second box, it rapidly mixes with the high temperature unburned gas, and as a result, the outer flame D is shortened. ,
Stable two-stage combustion can be performed. In addition, the protrusion of the first box body is provided below the secondary flame hole, but this can be used as a flame hole for the external flame D when the combustion amount is reduced, and the protrusion is provided below the secondary flame hole. By becoming a hole, the space between the primary flame hole and the protrusion, that is,
This shows that the combustion chamber volume can be varied depending on the amount of combustion.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. In FIG. 1, reference numeral 11 denotes a slit-shaped primary flame hole, which is placed over the opening of the air-fuel mixture chamber 13 of the premix combustion burner 12. This primary flame hole 11
is a first box body 15 with a secondary flame hole 14 formed on the top surface.
is surrounded by. The inside of the first box 15, that is, the inside of the combustion chamber 16, is shut off from the atmosphere, and secondary air is prevented from flowing into the inner flame C formed above the primary flame hole 11. The protrusion 17 inside the first box 15 is
They are provided at a position below the secondary flame hole 14, over the entire length in the longitudinal direction, on both left and right sides facing toward the inside of the combustion chamber 16. The second box 18 is the first box 1
5, but has openings at both ends,
A protrusion 19 is provided at a position above the secondary flame hole 14 so as to extend inward from both left and right sides.

In the above configuration, since secondary air does not flow into the first box 15, the premix combustion burner 1
The inner flame C corresponding to the primary air amount of 2 is the primary flame hole 11.
The high-temperature unburned gas that was formed above and whose combustion could not be completed by the amount of primary air is released above the secondary flame hole 14.
It diffuses and mixes with the secondary air that has passed through the gap between the first box 15 and the second box 18, forming an external flame D. This complete two-stage combustion makes it possible to achieve even better NOx reduction. At this time, the protrusion 17 of the first box 15 is formed by the process described below.
Contributes to flame stabilization when reducing the amount of combustion.
When the combustion amount starts to be reduced, the amount of high-temperature unburned gas mentioned above gradually decreases, and the outer flame D can no longer be formed on the secondary flame hole 14. This is due to the deterioration of flame stability due to a temperature drop at the edge of the secondary flame hole 14 due to the reduction of the combustion amount, and the lack of unburned gas. When a flame is not formed on the secondary flame hole 14, the secondary air, which has been unable to enter the combustion chamber 16, has no resistance and becomes easier to enter. on the other hand,
The protrusion 17 of the first box 15 is kept in a high temperature state due to heat transfer from the inner flame C and unburned gas. These conditions cause an external flame D to be formed in the protrusion 17 from the unburned gas and the secondary air that has flowed into the combustion chamber 16. Furthermore, when the combustion amount is reduced and conditions are reached such that no external flame D can be formed in the protrusion 17, the secondary air will diffuse to the vicinity of the primary flame hole 11. In this state, two-stage combustion is no longer maintained, but the primary flame hole 11
Above, a premixed flame is formed. As described above, according to the protrusion 17 of the first box body 15, even if the combustion amount is changed, a stable flame that is balanced with the conditions can be maintained. In addition, the protrusion 19 of the second box 18 changes the flow of secondary air in the direction of the central axis of the second box 18, so that the high temperature unburned gas flowing vertically upward is at a certain angle. As a result, the diffusion and mixing process between the two occurs more rapidly than when the two are diffused and mixed in a parallel state. As a result, secondary flame hole 1
The outer flame D formed on the secondary flame hole 1 where the unburnt gas and the secondary air are initially diffused and mixed is made into a short flame and is independent of the increase/decrease in the amount of primary and secondary air.
4, the second box body 1 is stably formed and
The external flame D is never formed on the protrusion 19 of No.8.

Effects of the Invention As described above, according to the combustion apparatus of the present invention, the following effects can be obtained.

By rapidly diffusing and mixing high-temperature unburned gas and secondary air, the outer flame can be shortened, and as a result, instability of the outer flame due to lack of primary air due to oxygen deficiency, damper clogging, etc. can be suppressed. , ensuring good combustion characteristics at all times.

Since the supply of secondary air can be reliably delayed, reliable two-stage combustion can be achieved and further reductions in NOx can be achieved.

Since the protrusion of the first box body can obtain a load on the combustion chamber according to the amount of combustion, it is possible to widen the width of the aperture of the amount of combustion.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a combustion device showing an embodiment of the present invention, and FIG. 2 is a side sectional view of a conventional example. 11...Primary flame hole, 12...Premix combustion burner, 14...Secondary flame hole, 15...First box body, 1
7...Protrusion of the first box, 18...Second box, 19...Protrusion of the second box.

Claims (1)

[Claims] 1. A premixed combustion burner having a primary flame hole, and a premixed combustion burner that houses the premixed combustion burner, is isolated from the atmosphere except for the secondary flame hole formed at one end, and is located below the secondary flame hole in a longitudinal direction. a first box body provided with a protrusion facing inward over the entire length; a first box body surrounding the first box body and having openings at both ends;
A combustion device comprising a second box body having a protrusion extending inward over the entire length in the longitudinal direction at a position above the second flame hole.