JPH06109218A - Premixing combustion apparatus - Google Patents

Abstract

PURPOSE:To ensure high load combustion add high turn-down ratio combustion by providing a guide wall protruded slantingly toward the outside in close vicinity of slit holes located on opposite sides of each chief flame hole portion. CONSTITUTION:An elongated slit hole 21a located on opposite sides and an elongated slit hole 21b disposed in the middle of the slit hole 21a are formed as a set of chief flame hole portions 20, 21, and a guide wall 30 protruded slantingly to the outside is provided near the elongated slit hole 21a disposed on opposite sides of each chief flame hole portions 20, 21. It is therefore possible to reduce a mixed gas velocity at a flame base portion, the mixed gas being combusted through the slit hole 21a on the opposite sides of the chief flame hole portion owing to the coanda effect even if the amount of combustion is increased, and combustion is stabilized by bringing a balancing point between it and a combustion speed toward a flame hole side. Hereby, high load combustion with a maximum combustion amount is ensured. Further, there is ensured the combustion of a high turn-down ratio even under a low input.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premix combustion apparatus in which air and fuel are premixed in a mixing chamber, and the mixture is blown out through a flame hole for combustion.

[0002]

2. Description of the Related Art Conventionally, Bunsen combustion has been the mainstream of continuous combustors using gas fuel, and premixed combustion has been put into practical use in some cases. Meanwhile, as means of the NO _X reduction in the exhaust, it is effective premixed combustion at a lean air-fuel mixture.

[0003]

However, in the above Bunsen combustion, since a high concentration of NO _X is generated in the wake of the high temperature internal flame, it is difficult to realize a low NO _X combustor. Moreover, since a large space is required for the secondary combustion, it is difficult to realize high-load combustion. In addition, in the above-mentioned premixed combustion, since the combustion speed is generally low, the flame is easily blown off, and the combustion amount is limited. Further, in the premixed combustion, the flame stable range is narrow, and in the practical combustor, the combustor structure for widening the flame stable range is generally complicated.

Therefore, the present invention solves the above-mentioned drawbacks of the prior art, makes use of the NO _X reduction effect of lean premixed combustion, achieves high-load combustion in which stable flame hardly blows off, and achieves combustion noise. It is an object of the present invention to provide a premixed combustion device capable of achieving high reduction of combustion and a high turndown ratio of combustion amount.

[0005]

In order to achieve the above object, the premixed combustion apparatus of the present invention premixes the air sent by the blower means and the fuel sent by the fuel supply means in the mixing chamber. The premixed combustion device is configured to blow out the premixed air from the main flame hole and the auxiliary flame hole to perform combustion, and the main flame hole is an elongated slit hole located on both sides and an intermediate portion thereof. The elongated slit holes or round holes provided are set as a set of main flame holes, and a set of main flame holes are arranged in a straight line to form a main flame hole row, and both main flame hole rows are formed. The first feature is that the guide wall is provided so as to be adjacent to the outer side in parallel and to be inclined and protruded to the outer side. In addition to the first feature, the premixed combustion device of the present invention is provided with auxiliary flame holes for feeding the premixed air having a high concentration along the outer periphery of the main combustion portion including the main flame hole array and the guide wall. This is the second feature.

[0006]

According to the first feature described above, the premixed air of fuel and air is supplied from below, blown out through the main flame holes and the auxiliary flame holes, and burned. Since the elongated slit holes on both sides of each set of main flame holes are provided with guide walls projecting inclining outwardly in close proximity, they were blown out through the elongated slit holes on both sides. The premixed air flows along the guide wall that is inclined and protrudes outward due to the Coanda effect,
The base of the flame is held in the middle of the inclined portion of the guide wall at a point balanced with the burning velocity. Then, a set of flames is formed by being combined with the flames that are blown out and burned from the remaining middle long slit holes or round holes. Due to the action of the guide wall sloping outward, each pair of flames lowers the air-fuel mixture velocity at the flame base, and thereby has high blow-off resistance even against high-load combustion. Further, according to the second feature, since the auxiliary flame holes for feeding the premixed air having a high concentration are provided along the outer periphery of the main combustion portion including the main flame hole row and the guide wall, the auxiliary flame in the auxiliary flame holes is provided. The combustion speed of the flame is increased, and a sufficiently stable auxiliary flame having a large flame holding effect is formed on the outer periphery of the main flame hole. Therefore, even if the air-fuel mixture blowing speed in the main flame hole becomes high, blow-off and extinguishing can be prevented, and high-load combustion can be performed. Further, since the flame is stably formed in the main flame hole, the combustion noise can be suppressed low.

[0007]

1 is a vertical sectional view of the apparatus for carrying out the present invention, FIG. 2 is a plan view of the apparatus for carrying out the present invention, FIG. 3 is a detailed perspective view of a main flame hole portion and a guide wall, and FIG. 4 is a main flame hole portion. It is a detailed perspective view which shows the other example of a guide wall.

An air blower 15 serving as an air blower is provided below the case 10.
The fuel supply pipe 13 from the fuel supply means (not shown) is connected to the passage from the blower 15. Inside the case 10, the lower part partitioned by the partition plate 14 is a mixing chamber 12, and the main flame hole array 20 is located above the partition plate 14.
And a main combustion section formed by repeating the guide wall 30 and an auxiliary flame hole 40 surrounding and surrounding the main combustion section.

Each of the main flame hole rows 20 is composed of three main flame hole portions 21, and a plurality of main flame hole portions 21 are arranged on a straight line (four in the embodiment).
One main flame hole row 20 is made. The main flame hole row 20 is composed of seven rows in the embodiment. Each pair of main flame holes 21
Is composed of a long-diameter slit hole 21a located on both sides and another long-diameter slit hole 21b provided in the middle. Alternatively, the long-diameter slit hole 21b provided in the middle may be a small-diameter round hole 21c, as shown in FIG. The dimensions of the respective holes 21a, 21b of the main flame hole portion 21 are set so that the premixture blow-off speed is always higher than the combustion speed so as to prevent backfire even when the combustion amount is reduced.

The guide wall 30 is provided so as to project in parallel to the main flame hole array 20 in parallel and inclines upward from a position close to the long-diameter slit holes 21a outside each main flame hole portion 21. A pair of wall surfaces 31 is provided.

A premixed gas having a higher concentration than the premixed gas supplied to the main flame hole 21 is introduced into the auxiliary flame hole 40. Therefore, the auxiliary combustion supply pipe 16 is connected to the space 17 before the auxiliary flame hole 40. As a result, the auxiliary flame hole 40
A rich premixed gas near the stoichiometric ratio, which is higher than that in the main flame hole, or exceeding that is supplied to.

During operation, after the combustion air from the blower 15 and the fuel from the fuel supply pipe 13 are thoroughly mixed in the mixing chamber 12,
It is distributed to each flame hole through the hole of the partition plate 14. The premixed gas blown out from the slit holes 21a outside the pair of main flame holes 21 flows along the wall surface 31 inclined to the outside of the guide wall 30, and the wall surface 31 in which the combustion velocity and the premixed air velocity are balanced The base outside the flame is held in the middle position. The premixture blown out from the intermediate flame hole 21b and the premixture passing through the outer flame hole 21a constitute the main flame 18. Surrounding auxiliary flame hole 40
A premixed gas having a higher pore concentration is supplied from, and the stability of the auxiliary flame 19 is greater than that of the main flame 18 due to the high burning rate, and the flame holding effect is exhibited.

In the above embodiment, the turndown ratio can be set to about 1: 5 to 6 without switching the combustion surface, which is about twice as wide as that of the conventional gas appliance. The amount of NO _X emission is about 30 ppm at an excess air ratio of 1.4, which is about 1/4 of that of a conventional general Bunsen combustor. Further, since the holes 21a and 21b of each main flame hole portion 21 have a relatively small size, a backfire is unlikely to occur even if the combustion amount is reduced.

[0014]

According to the premixed combustion apparatus of the first aspect of the present invention, the premixed combustion apparatus according to the first aspect of the present invention is provided outside in proximity to the elongated slit holes on both sides of each main flame hole portion. Since the guide wall that is inclined and projected is provided, even if the combustion amount is increased, the mixture velocity of the flame base portion that burns through the slit holes on both sides can be reduced by the Coanda effect. The equilibrium point with can be made closer to the flame hole side and stabilized. Further, as a result of stabilizing the flame, combustion noise can be suppressed low. As described above, it is possible to perform high-load combustion with a large maximum combustion amount, and also possible to perform combustion with a high turndown ratio that does not cause flashback even at low input. Of course, because of premixed combustion, low NO _X combustion is possible. According to the premixed combustion apparatus described in claim 2, in addition to the effect of the configuration described in claim 1, the premixed combustion apparatus having a high concentration along the outer periphery of the main combustion portion including the main flame hole array and the guide wall is provided. Since the auxiliary flame hole for feeding the air-fuel mixture is provided, the combustion speed of the auxiliary flame in the auxiliary flame hole is increased, and even if the combustion amount is increased, the auxiliary flame having a sufficiently stable flame holding effect is provided on the outer periphery of the main flame hole portion. Can be formed. Therefore, blowout is further prevented, and high-load combustion can be performed. Further, the combustion noise can be further suppressed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a device embodying the present invention.

FIG. 2 is a plan view of an apparatus for carrying out the present invention.

FIG. 3 is a detailed perspective view of a main flame hole portion and a guide wall.

FIG. 4 is a detailed perspective view showing another example of the main flame hole portion and the guide wall.

[Explanation of symbols]

 10 Case 12 Mixing chamber 13 Fuel supply pipe 14 Partition plate 15 Blower 16 Auxiliary fuel supply pipe 18 Main flame 19 Auxiliary flame 20 Main flame hole array 21 Main flame hole portion 21a Long slit 21b Intermediate hole 30 Guide wall 31 Wall 40 Auxiliary flame hole

Claims (2)

[Claims] 1. The air sent by the blower means and the fuel sent by the fuel supply means are premixed in a mixing chamber, and the premixed gas is blown out from the main flame holes and the auxiliary flame holes to perform combustion. In the premixed combustion device as described above, the main flame hole is a pair of main flame hole portions having elongated slit holes located on both sides and elongated slit holes or round holes provided in the middle, The main flame hole rows were formed by arranging a large number of this set of main flame hole portions on a straight line, and a guide wall was provided that was adjacent to both outer sides of each main flame hole row in parallel and inclines outward. A premixed combustion device characterized by the above. 2. The premixed combustion apparatus according to claim 1, wherein auxiliary flame holes for feeding the premixed gas having a high concentration are provided along the outer periphery of the main combustion portion including the main flame hole array and the guide wall.