JPH09222203A - Inner directed flame burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low NOx emission and improve a thermal efficiency by a method wherein a row of flame holes are, arranged at a wall surface of a burner main body, pre-mixed gas having air less than a specified value of a theoretical combustion air volume is injected out of the flame holes, a shielding plate for closing a lower part of a space is arranged, and its opening or closing may easily be carried out. SOLUTION: Either a number of vertical slits or a plurality of flame holes 3 are arranged at an upper part of an inner circumferential wall of a horizontal ring-shaped burner main body 1. Then, a shielding plate 4 for use in closing an air blowing-off space 2 at the central part of the burner is arranged below the flame holes 3, a concave part A is formed at the central part of the burner main body 1. A mixing ratio of primary air is adjusted in such a way that the pre-mixed gas having an air volume approximate to a theoretical value to low pressure gas such as municipal gas or the like (less than ±30% of the theoretical combustion air volume, for example) may be infected out of the flame holes 3. In addition, the shielding plate 4 is formed in such a way that it may be freely rotated, opened or closed, its opening or closing operation is set to be cooperatively operated with a gas plug 5 under an operation of a cooperating mechanism 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a Bunsen type low pressure gas burner used for a gas stove, a water heater, or the like.

[0002]

2. Description of the Related Art Generally, in this type of burner, a large-capacity burner, which is often used for business purposes, has a large flame length. Therefore, in a ring burner having a main flame hole on the outer peripheral surface, the diameter of the pot bottom is relatively large. Has a problem that the maximum temperature part of the flame comes out to the outside of the bottom of the pot and the thermal efficiency drops, and as a countermeasure against that, a so-called inward flame burner with flame holes on the inner peripheral surface of the ring burner was developed. Has been done. FIG. 3 shows an example of the structure, in which the flame holes 3 are arranged in a row on the inner peripheral surface of the horizontal ring-shaped burner main body 1, and the flame is jetted inward, which is once the bottom surface of the heated container. In order to fold back just below the center and reach its outer edge,
This increases the contact time between the flame and the bottom of the pot, improving the thermal efficiency.

[0003]

In the above-mentioned inward flame burner, when the primary air amount is increased and the flame length is shortened in order to improve the thermal efficiency, the maximum temperature point of the flame becomes close to the center of the pot bottom. On top of that, the momentum of the flame that impacts the bottom of the pot increases, which has the advantage of improving the heat transfer coefficient from the flame to the bottom of the pot, but on the other hand, because the combustion temperature rises, the amount of NOx generated increases, and particularly high capacity This is a problem for commercial burners. The present invention has been made in view of the above problems, and an object thereof is to provide a burner having low NOx and high thermal efficiency.

[0004]

As shown in FIGS. 1 and 2, the present invention is directed to a burner body facing a central blow-through space 2 of two Bunsen low-pressure burners 1 in a ring shape or in parallel and in a straight tube shape. Flame holes 3 are lined up on the wall surface, and a premixed gas mixed with air having a substantially theoretical mixing ratio (within ± 30% of the theoretical combustion air amount) is ejected from these flame holes 3 and the lower portion of the space 2 is ejected. A shield plate 4 for closing is provided so that the shield plate 4 can be opened and closed freely. In view of the fact that the excessively supplied secondary air contributes to the high NOx generation rate, the inward flame burner The structure is characterized in that the central blow-through space 2 is closed to cut off the supply of excessive secondary air. Since the Bunsen burner sucks primary air from the surroundings by the kinetic energy of the jetted gas in the mixing tube, the primary air suction force decreases when the gas flow velocity is small and the thermal power is small. Therefore, when the gas cock 5 is throttled, the shield plate 4 is opened to supply abundant secondary air to prevent incomplete combustion.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, in which a large number of vertical slit-shaped flames or a plurality of stages of flames are formed on the entire upper circumference of the inner peripheral wall of the horizontal ring-shaped burner body 1. Hole 3
Are provided in rows, a shield plate 4 for closing the blow-through space 2 in the center of the burner is provided below the flame hole 3, and a recess A is formed in the center of the burner body 1. The mixing ratio of the primary air is adjusted so that the premixed gas obtained by mixing the low-pressure gas (300 mmH ₂ O or less) such as city gas with the air amount close to the theoretical value (for example, within ± 30% of the theoretical air amount) from 3 is ejected. Is being adjusted. According to this configuration, during the combustion by the large thermal power, the secondary air is hardly supplied into the recess A and the space between the upper surface of the burner body 1 and the heated container, and therefore the flame is burned. Air is not supplied in excess of the necessary and sufficient amount of air, so that the generation of NOx due to excessive supply of oxygen is suppressed, and high load and low NO
x gas burners are realized. The shield plate 4 is formed so as to be rotatable and openable, and its opening / closing operation is interlocked with the gas cock 5 by an interlocking mechanism 6. Reference numeral 7 is a mixing tube, and 8 is an ejector nozzle, which sucks primary air from the surroundings at a fuel gas ejection speed to perform premixing.

The dotted line in FIG. 1 shows the state when the gas cock is fully opened and at the time of large thermal power, and the blow-through space 2 at the center of the burner body 1 is closed by a shielding plate 4. Since the premixed gas, which is a mixture of air and air that is close to the theoretical combustion air amount, is ejected from the flame hole 3, complete combustion is possible without the supply of secondary air. Since the flow from the inside to the outside is dominant in the gap of,
Almost no secondary air is supplied to the high temperature portion of the flame, so that the generation of NOx due to excessive secondary air can be prevented.

For example, when stir-frying in a Chinese restaurant, the gas cock 5 is squeezed to reduce the heating power. Generally, however, the Bunsen type burner has a low primary air suction force at the time of a small heating power with a small gas flow velocity and a secondary air suction force. Incomplete combustion occurs without air supply. Therefore, the shield plate 4 is interlocked with the gas cock 5, and when the fire power is small, as shown by the broken line in FIG.
To open. In the figure, reference numeral 6 shows an example of an interlocking mechanism, in which a sliding rod 10 which is guided by a guide 9 and slides at the time of large heat is a lever 11 of a gas cock 5.
The shield plate 4 is pressed against the tension spring 12 against the tension spring 12.
Is rotated and the pressing force of the lever 11 is released when the heating power is small, so that the shield plate 4 returns to the position indicated by the solid line by its own weight.

FIG. 2 shows another embodiment of the present invention, in which a large number of flames are provided over the entire length above the opposite surfaces of the two straight tubular burner bodies 1 arranged horizontally and in parallel. In addition to providing the hole 3, a shield plate 4 for closing the blow-through space 2 at the center of the burner is provided below the lower end of the flame hole 3 so that the shield plate 4 can be opened and closed vertically. This is exactly the same as in the case of the ring burner of FIG.

FIG. 3 shows still another embodiment, which is a large thermal power range (8000 Kcal / h) used for commercial use.
In the above, the main burner 1 is normally ignited via the pilot burner 13 in order to prevent explosive ignition. In this embodiment, this pilot bar
A cover 13 is provided below the shielding plate 4 to protect it from spilled juice. By doing so, the flame holes of the pilot burner 13 and the electrodes of the ignition plug 14 are not contaminated, and there is an advantage that durability is increased and there is no possibility of causing an operation error.

[0010]

As described above, the inward flame burner according to the present invention is designed to inject a premixed gas having a theoretical amount of air from the flame holes 3 provided on the wall surface in the blow-through space 2 closed by the shield plate 4. Therefore, there is an advantage that the secondary air is hardly supplied to the space between the upper surface of the burner body 1 and the object to be heated at the time of a large thermal power, and thus the generation of NOx due to excessive supply of oxygen is suppressed. Since the shield plate 4 is opened to supply the secondary air through the blow-through space 2 when the heat power is small, it is possible to compensate for the shortage of the primary air suction amount due to the fuel gas at the time of turndown, thereby causing incomplete combustion. There is an advantage that it can be prevented. Further, since the shielding plate 4 is opened and closed, there is an advantage that boiled spilled juice, dust and the like are unlikely to be accumulated in the recess A and cleaning is easy.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention.

FIG. 2 is a perspective cutaway view of an essential part of another embodiment of the present invention.

FIG. 3 is a cutaway perspective view of a main part showing still another embodiment of the present invention.

FIG. 4 is a cutaway perspective view of a main part of a conventional example.

[Explanation of symbols]

 1 Burner Main Body 2 Blowing Space 3 Flame Hole 4 Shielding Plate 5 Gas Cock 6 Interlocking Mechanism 7 Mixing Pipe 8 Ejector Nozzle 9 Guide 10 Sliding Rod 11 Lever 12 Tension Spring 13 Pilot Burner 14 Spark Plug A Recess

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masafumi Matsubara 507-2 Shintakaracho, Tokai City Toho Gas Co., Ltd.

Claims (2)

[Claims] 1. A flame hole is provided on a wall surface of a burner body facing a central blow-through space of two ring-shaped or parallel straight tubular Bunsen low-pressure burners, and the theoretical combustion air amount ± An inward flame burner in which a premixed gas mixed with air within 30% is ejected and a shield plate for closing the lower part of the space is provided so that the shield plate can be opened and closed. 2. The inward flame burner according to claim 1, wherein the opening / closing operation of the shielding plate is interlocked with a gas cock for fuel supply of the burner.