JPS62715A - Combustion device - Google Patents

Abstract

PURPOSE:To provide a positive stable two=stage combustion and enable a combustion of low NOx to be carried out by a method wherein a casing B enclosing a casing A shielded against the surrounding atmosphere, having at its one end an opening part and forming an inward projection at a position higher than a secondary flame hole is arranged. CONSTITUTION:Since a secondary air is not flowed into a casing A15, an inner flame 16 corresponding to an amount of primary air in a premixing combustion burner 12 is formed over primary air holes 11, the hot non-ignited gas is dispersed with and mixed with the secondary air over the secondary flame holes 14 which is passed through a clearance between the casings A15 and B18 so as to form an outer flame 20. With such a complete two-stage combustion, it is possible to make a low NOx. In this case, since the secondary air is changed t flow toward the central axis of the casing B18 by the projection 19, so the air is struck against the hot non-ignited gas at a certain angle thereto, thereby their dispersing and mixing process comes into a rapid processing state. As a result, the outer flame 20 is reduced to a short flame and at the same time a table flame is formed only above the secondary flame holes 14 not depending upon the increasing or decreasing of the primary and secondary air volumes.

Description

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

2. Description of the Related Art As shown in FIG. 2, a conventional combustion apparatus of this type includes a premixing chamber 1 in which a part of combustion air is premixed with gaseous fuel as primary air, and a premixing chamber 1 provided in this premixing chamber 1. A flame hole body 2 which is horizontally long and has a large number of flame holes, 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 with a gap between them. It consisted of a secondary air chamber 4, which is surrounded by air and supplies combustion secondary air above the primary combustion chamber 3, and a rectifying plate 5 provided above the primary combustion chamber a.

(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 outer flame is formed above the primary combustion chamber 3 or between the baffle plates 5 depending on the amount of unburned gas and the amount of secondary air. Therefore, in the transition state, the outer flame tends to become unstable and the combustion intermediate pressure is increased. The problem was that substances were easily generated.

The present invention solves such conventional problems, and aims to realize a low NOx combustion device through reliable and stable two-stage combustion.

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, and a secondary combustion burner housing the premix combustion burner and formed at one end. A box body A that is isolated from the atmosphere except for the flame hole, and a box that surrounds the box body A, has an opening at one end, and has a protrusion facing inward at a position above the secondary flame hole. It consists of body B.

Effect The present invention has the above-described configuration, and one of the premix combustion burners.
Since the secondary flame hole is completely surrounded by the box body with the secondary flame hole, the secondary air does not flow into the primary flame hole and is diffused with unburnt gas above the secondary flame hole. Mix. Therefore, the inner flame//i primary flame hole upper flame is formed above the secondary flame hole.

Moreover, because the secondary air flows in the direction of the center axis of box B through the protrusion of box B, it rapidly mixes with unburned gas, shortens the outer flame, and ensures reliable and stable two-stage combustion. can be done.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. In FIG. 1, 11 is a slit-shaped primary flame hole, which is placed over the opening of the mixing chamber 13 of the premix combustion burner 12. This primary flame hole 11 is surrounded by a box A15 having a secondary flame hole 14 formed on its upper surface. In other words, box A
The interior of the combustion chamber 15 except for the secondary flame hole 14 is shut off from the atmosphere, thereby preventing secondary air from flowing into the combustion chamber 17 of the inner flame 16 formed above the primary flame hole 11 . The box body B18 surrounds the box body A15, has openings at both ends, and has secondary flame holes 1.
By providing the protrusion 19 facing inward at the position above 4, the flow of secondary air flowing through the gap between the box body A15 and the box body B18 is controlled in the direction of the central axis of the box body B18. .

In contrast to the above configuration, since secondary air does not flow into the box A15, an inner flame 16 corresponding to the amount of primary air of the premix combustion burner 12 is formed above the primary flame hole 11, and the primary air The high-temperature unburned gas that could not be completely burned by the amount alone diffuses and mixes with the secondary air that has passed through the gap between the box body A15 and the box body B18 on the secondary flame hole 14, forming an outer flame 20. do. This complete two-stage combustion provides even better low NOx emissions.
can be achieved. At this time, the secondary air flows through the protrusion 1 of the box B18.
9 changes the flow in the direction of the central axis of the box body B18, so it collides with the high temperature unburned gas flowing vertically upward at a certain angle, and the diffusion mixing process between the two Compared to the case of diffusion mixing in a parallel state, the state becomes more rapid. As a result, the outer flame 20/ri formed on the secondary flame hole 14 is shortened, and the unburnt gas and the secondary air are first diffused and mixed regardless of the increase or decrease in the amount of primary and secondary air. is stably formed only on the secondary flame hole 14,
This has the effect that an external flame 20 is never formed in the protrusion 19.

Effects of the Invention As described above, the combustion apparatus of the present invention provides the following effects.

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

(2) Since the supply of secondary air can be reliably delayed, reliable two-stage combustion can be realized and further reduction in NOx can be achieved.

(3) Although the box B receives radiant energy from the outer flame and constantly generates thermal stress, deformation can be suppressed by providing the protrusion.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing one 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...
・Box A, 18...Box B, 19...
protrusion.

Claims (1)

[Claims] a premix combustion burner having a primary flame hole; a first box housing the premix combustion burner and shielded from the atmosphere except for a secondary flame hole formed at one end; and a first box surrounding the first box. and a second box body having an opening at one end and an inwardly projecting portion formed above the secondary flame hole.