JPS62108906A - Burner unit - Google Patents

Abstract

PURPOSE:To constantly secure an excellent combustion characteristic and reduce NOx as less as possible by abruptly diffusing and mixing a high-temperature unburnt gas and secondary air. CONSTITUTION:Slit-like primary flame holes 11 are provided to cover the opening of a gaseous chamber 13 of a premixing combustion burner 12. These burner ports 11 are encircled by a first box member 15 in which secondary burner ports 14 on the upper surface. The inside of the box member 15, that, is, the inside of a combustion chamber 16, is interrupted from the atmosphere to check the inflow of secondary air into an internal flame C. Projections 17 within the first box member 15 are provided at positions which are lower than those of secondary burner ports 14 over the entire length of a longitudinal direction on both right and left sides in opposite to the inner side of a combustion chamber 16. A second box member 18 encircles the first box body 15 and has opening on both ends, projections 19 are provided at positions at the upper part of secondary burner ports 14 from both right and left sides toward the inner side. Accordingly, a high-temperature unburnt gas is diffusion-mixed with secondary air which has passed gap formed between the first box body 15 and the second box body 18.

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 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 long and has a large number of flame holes provided, a primary combustion chamber 3 on the upper part of this flame hole body 2, a circumferential wall of the single-fire combustion chamber a and the premixing chamber 1, with a gap between them. It consisted of a secondary air chamber 4 that surrounds the combustion chamber and supplies combustion secondary air above the primary combustion chamber 3, and a rectifier 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 outer flame is formed on 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 combustion intermediate generation occurs. The problem was that substances were easily 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, and a secondary combustion burner housing the premix combustion burner and formed at one end. Everything except the flame hole is shielded from the atmosphere.
! fr shi, a first box body provided with a protrusion facing inward over the entire length in the longitudinal direction at a position below the secondary flame hole, and a first box body surrounding the first box body and having openings at both ends. and a second box in which a projection is formed inward over the entire length in the longitudinal direction at a position above the secondary flame hole.

Effect The present invention has the above-described configuration, and one of the premix combustion burners.
Because the flame hole is completely surrounded by the first box body having the secondary flame hole, secondary air does not flow over the primary flame hole;
It diffuses and mixes with unburned gas above the secondary flame hole. Therefore, the inner flame C is formed on the primary flame hole, and the outer flame C is formed on the second flame hole. Moreover, since the secondary air flows in the direction of the central axis of the second box through the projections of the second box, it rapidly mixes with the high-temperature unburned gas, and as a result, the outer flame is shortened. Stable two-stage combustion can be performed. In addition, the protrusion of the first box is provided below the secondary flame hole, but this can be used as a flame hole for external flame when the combustion amount is reduced, and the protrusion is also provided below the secondary flame hole. By forming the hole, the space between the primary flame hole and the protrusion, that is, the volume of the combustion chamber, can be varied depending on the amount of combustion.

Embodiment Embodiment F, 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 one missing flame hole 11 is surrounded by a first box 15 having a secondary flame hole 14 formed on its upper surface. The inside of the first box 15, that is, the inside of the combustion chamber 16 is isolated from the atmosphere, and the inside of the combustion chamber 16 is isolated from the atmosphere.
This prevents secondary air from flowing into the inner flame C formed above the secondary flame hole 11. The protrusion 17 in the first box 15 is located below the two flame holes 14 and extends over the entire length in the longitudinal direction.
They are provided on both the left and right sides facing the inside of the combustion chamber 16. Second
The box body 18 surrounds the first box body 15, has openings at both ends, and has protrusions 19 provided above the two flame holes 14 inward from both left and right sides. ing.

In the configuration, since secondary air does not flow into the first box 15, an inner flame C corresponding to the primary air flow of the premix combustion burner 12 is formed on one flame hole 11, and one The high-temperature unburned gas that could not be completely burned with just the amount of air
On the second flame hole 14, it diffuses and mixes with the secondary air that has passed through the gap between the first box body 15 and the second box body 18, forming an outer flame. Such complete two-stage combustion allows for even more excellent reduction in NOx. At this time, the protrusion 17 of the first box 15 contributes to stabilizing the flame when the combustion amount is reduced through the process described below.

When the combustion amount starts to be reduced, the amount of high-temperature unburned gas mentioned above gradually decreases, and an outer flame can no longer be formed on the secondary flame hole 14. This is achieved by reducing the amount of combustion.
This is caused by deterioration of flame stability due to temperature drop at the edge of the second flame hole 14 and lack of unburned gas.

Unless a flame is formed on the secondary flame hole 14, until then...
The secondary air that has not been able to enter the combustion chamber 16 has no resistance and can easily flow into the combustion chamber 16. 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 unburned gas of the inner flame C1. These conditions cause an outer flame to be formed in the protrusion 17 from the unburned gas and the secondary air that has flowed into the combustion chamber 16. Further, when the amount of combustion is reduced and conditions are reached such that no external flame can be formed on the front first grip projection 17, the secondary air will diffuse to the vicinity of the primary flame hole 11. In this state, second-stage combustion is no longer maintained, but a premixed flame is formed above the primary flame hole 11. As described above, according to the protrusion 17 of the first box 15, even if the combustion amount is changed, a stable flame that is balanced with the conditions can be maintained. Also,
The protrusion 19 of the second box 18 deforms 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 mixing process between the two occurs more rapidly than when the two are diffusive and mixed in a parallel state. As a result, the outer flame 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. The flame is stably formed on the secondary flame hole 14, and an outer flame is never formed on the protrusion 19 of the second box body 18.

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

■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 lack of oxygen, damper clogging, etc. can be suppressed, and good combustion characteristics can always be ensured.

I] 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.

(2) 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 throttle of the amount of combustion.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a combustion device showing one embodiment of the present invention;
FIG. 2 is a side sectional view of a conventional example. 11...Primary flame hole, 12...Premix combustion burner, 1
4 ・Secondary flame hole, 15...first box body, 17...first
protrusion of the box, 18...second box, 19. protrusion of the second box; Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (1)

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