JPS63263313A - Burner - Google Patents

Abstract

PURPOSE:To reduce the amount of the generation of NOx and prevent the lifting of flame and make it possible to enlarge the range of the variability in the amount of combustion by placing combustion plates each of which holds flame plates constituted by metal nets so as to oppose each other with a certain distance between them and constituting the combustion plates so as to give an increased flow channel resistance in the perpheral sections compared with the central sections of the flame plates. CONSTITUTION:A flame plate 14 is formed to have a metal net 14c which has its central section cut off and is placed between two metal nets 14a and 14b. The flame plates 14 on both combustion plates 15 face each other one to one with the opposing flame plates. When the flow rate of a premix gas 11 is large, the temperature in a combustion chamber 20 rises rapidly in actuality, but because the flame plate 14 is divided in a plurality of sections, the heat radiation at the central section of the combsution plate 15 is large so that the generation of NOx is reduced. On the side of the high air ratio in stable combustion range, the flow resistance in the periphery of the metal nets 14a and 14b and 14c is increased by them so that the flow rate is reduced and the lifting of flame can be prevented. Because of the enlargement of the stable combustion range on the side of high air ratio, actually the range of variability in the combustion amount for high combustion amount control is widened.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a low NOx burner used in an indoor open type combustor or the like.

BACKGROUND OF THE INVENTION Conventionally, burners that utilize complete premix combustion have been used as such burners.For example, as shown in FIG. was provided as a burner port plate, an outer premixture road 3 was formed by the outer burner port plate 2 and the outer wall 1, and an inner premixture passage 6 was formed in the inner burner port plate 4.

Problems to be Solved by the Invention However, in such a burner, each burner plate 2.4
The central part of the flame dissipates less heat than the peripheral part adjacent to the outer wall, so the flame in the central part has less heat dissipated via the flame plate, so the temperature is not high, and the amount of NOx generated is low. There were a lot of them. On the other hand, the amount of heat radiated by the flame in the vicinity of the flame port plate is large and the combustion rate is reduced, so lifting is accelerated to narrow the variable range of combustion amount.

The present invention provides a burner with a simple configuration, low NOx emissions, and a wide variable range of combustion amount.

Means for Solving the Problems The present invention has a combustion plate holding a plurality of flame port plates made of wire mesh facing each other at a certain distance, and a combustion chamber composed of the combustion plates, a bottom plate, and a side plate. In the premix passage formed by the combustion plate and the outer wall, the flow path resistance is increased in the peripheral portion of each of the burner ports compared to the central portion.

action The effect of this technical means is as follows.

With the above configuration, the heat of the flame formed on the burner port plate at the center of the combustion plate can be effectively radiated, the flame temperature can be lowered, and the amount of NOx generated can be reduced.

At the same time, it is possible to prevent lifting of the flame around the burner port plate during combustion at a high air ratio, thereby widening the range in which the combustion amount can be varied in practical use as a burner.

Embodiment FIG. 1 is a perspective view of a burner according to an embodiment of the present invention, partially showing the internal structure.

First, the premixture 11 flows into the premixture passage 13 via the premixture supply pipe 12 . In order to perform completely premixed combustion in the burner of this embodiment, the premixture 11 is a completely premixed mixture,
In other words, the air ratio is 1 or more.

The premixture passage 13 includes a combustion plate 16 holding a plurality of burner ports 14 in a staggered arrangement, and an outer wall 17 partially made of heat-resistant glass 16. Here, as shown in FIG.
, 14b, there is a wire mesh 140 cut out in the center.
It is formed by sandwiching it. Further, each of the burner port plates 14 on the internal combustion plate 16 faces the opposing burner port plate 14 on a one-to-one basis.

On the other hand, the combustion plate 16 constitutes a combustion chamber 2o from a side plate 18 and a bottom plate 19, and surrounds a plurality of flames stabilized on the flame port plate 14.

The specific operation of this embodiment having such a configuration will be described below.

When the flow rate of the premixture 11 is large, the combustion load within the combustion chamber 20 becomes large when the amount of combustion is large, and the temperature within the combustion chamber actually increases rapidly. The flame is transferred to the combustion plate 16 by heat transfer or radiation. Flame port plate 14, side plate 18, and bottom plate 1
In particular, the flame in the center of the combustion chamber 2o radiates heat not only to the flame port plate 14 but also to the adjacent combustion plate 16. Therefore, compared to the conventional case where a single flame port plate is used, since the flame port plate 14 is divided into a plurality of pieces, the amount of heat radiated from the flame in the central part of the combustion plate 16 is large, and therefore thermal NOx is generated. Volumes have been reduced. In addition, outer wall 1
The heat-resistant glass 16 provided in the flame port plate 1 is heated by radiation.
4. This helps to lower the temperature of the combustion plate 15 uniformly.

Generally, as shown in FIG. 3, on the high air ratio side of the stable combustion range, the flame lifts at the peripheral portion of the burner port plate 14 in contact with the combustion plate 16.

The heat of the flame is mainly radiated to the flame outlet plate 14. In other words, the premixture 11 is preheated and heated through the hot flame port plate 1, and is immediately combusted. However, the temperature of the burner port plate 14 decreases in the peripheral portion of the burner port plate 14 in contact with the combustion plate 16.
The preheating effect of the premixture is small, so the combustion speed of the flame decreases and lifts. However, as in this embodiment, each burner port plate 14 is made of overlapping wire meshes 141L and 14b.

140 increases the flow path resistance in the peripheral area, the flow velocity of the premixture in the peripheral area is reduced, the preheating effect is increased, and lifting of the flame can be prevented.

As a result, the stable combustion range has expanded to the high air ratio side, and the performance as a burner has improved.

In particular, when the combustion amount is large, the temperature of the flame port plate 14 rapidly rises and becomes red-hot on the low air ratio side of the stable combustion range, as shown in FIG. This is because the flame outlet plate 14 and combustion plate 1
This is because the amount of heat dissipated from No. 5 does not increase much, but due to the durability of the wire mesh 141L, the range of air ratio variation within the stable combustion range has actually been narrowed. Therefore, the upper limit of the combustion amount variable range for the burner was determined. However, in the case of this example,
As a result of the above-mentioned effect, the stable combustion range has been expanded to the high air ratio side, which means that the combustion amount variable range has actually been expanded to the high combustion amount side.

Note that when the combustion amount is low, since the flame is divided to lower the flame temperature, carbon monoxide and the like are likely to be generated due to incomplete combustion. However, due to the configuration in which the flame port plates 14 are opposed to each other as in this embodiment, a high temperature region is formed in the wake of each flame, and the incomplete combustion components generated can be completely treated without being discharged downstream. ing. Further, the plurality of burner ports 14 are arranged in a staggered manner, which prevents incomplete combustion components particularly from the periphery of each burner port 14 from flowing out of the burner.

As described above, the amount of NOx emissions is reduced by lowering the flame temperature, and the stable combustion range is expanded to the high air ratio side by preventing lifting of the flame around the periphery of each flame plate, and the range of stable combustion to the high combustion amount side is accordingly increased. The stable combustion range has been expanded.

Effects of the Invention The present invention expands the range of stable combustion to the high air ratio side by preventing flame lifting in the periphery of each flame plate when the flame plate is divided to reduce NOx. The combustion range on the high combustion amount side has been expanded.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional perspective view of a burner according to an embodiment of the present invention;
FIG. 2 is an exploded view of the flame port plate of the burner, FIG. 3 is a schematic view showing the stable combustion range, and FIG. 4 is a sectional view of the main part of the conventional burner. 1...Outer wall, 2...Outer flame outlet plate, 4.
...Inner flame outlet plate, 14... Flame outlet plate, 16
... Combustion plate, 16 ... Heat-resistant glass, 2
0... Combustion chamber. Name of agent: Patent attorney Toshio Nakao and 1 other person14
-°-Flame plate Figure 1 20-Combustion chamber 121! W Figure 3 ◆ Celebration #

Claims (5)

[Claims] (1) Combustion plates holding a plurality of flame port plates made of wire mesh are opposed to each other at a certain distance, the combustion chamber is constituted by the combustion plates, the bottom plate and the side plates, and the premixed air is created by the combustion plates and the outer wall. A burner having a passage formed therein, characterized in that a peripheral portion of each of the burner port plates has a flow passage resistance increased compared to a central portion. (2) The method according to claim 1, wherein a wire mesh and a wire mesh with a central portion cut out are overlapped to increase flow path resistance in the peripheral portion of each burner port plate compared to the central portion. Burna. (3) The burner according to claim 1 or 2, wherein a part of the outer wall is made of a heat-transparent material such as heat-resistant glass. (4) In the opposing combustion plates, each burner port plate faces one-to-one. Claim 1, 2, or 3
Burner as described in section. (5) Claim 1, characterized in that at least those of the burner ports that are close to the combustion chamber are arranged in a staggered manner;
The burner according to item 2, 3 or 4.