JPH0642718A - Gas burner - Google Patents

Abstract

PURPOSE:To provide a gas burner capable of reducing an amount of generated NOx and further capable of increasing a turn-down ratio. CONSTITUTION:A plurality of mixed gas ejecting segments 2A and 2B for ejecting mixture gas of fuel gas and combustion air are arranged side by side in a mixture gas supplying direction of a mixture gas supplying part B for supplying mixture gas to these plurality of mixture gas ejection segments 2A and 2B and further the mixture gas is ejected into the same combustion space 3. The mixture gas supplying part B is constructed such that a supplying pressure of the mixture gas supplied to the mixture gas ejection part 2B located at a downstreams die in the mixture gas supplying direction is set to be higher than a supplying pressure of the mixture gas supplied to the mixture gas ejection part 2A located at an upstream side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas burner used for small gas appliances such as hot air heaters.

[0002]

2. Description of the Related Art In such a gas burner, it is required to reduce the NOx generation amount and increase the turndown ratio. Conventionally, a dilute mixed gas having a high excess air ratio is formed by a wire mesh of iron, copper, stainless steel or the like. All primary lean burn type in which lift is prevented and combustion is performed by suppressing the jet velocity, or mixed gas with a low excess air ratio is first burned in the first stage and insufficient air is supplied as secondary combustion air in the second stage. It was a two-stage combustion type configuration that burns by combustion.

[0003]

However, in the above-mentioned conventional gas burner having the structure of all primary lean burn type,
The flame temperature is lowered by burning the lean mixed gas, and the NOx generation is suppressed by the reducing action of the wire mesh of iron, copper, stainless steel, etc.
Although the generated amount can be reduced, in the low input range where the mixed gas supply amount is small, the flow resistance of the mixed gas becomes large due to the wire mesh, and the jetting of the mixed gas becomes unstable and stable combustion cannot be performed. There was a problem that the ratio could not be increased.

Further, in the conventional gas burner of the two-stage combustion type, there is no one that increases the flow resistance of the mixed gas such as wire mesh, so that stable combustion is achieved even in the low input range where the mixed gas is supplied in a small amount. Although it is possible to increase the turndown ratio, there is a problem that the NOx generation amount increases because the flame temperature rises because the mixed gas having a low excess air ratio is burned in two stages.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a gas burner capable of reducing the NOx generation amount and increasing the turndown ratio.

[0006]

The gas burner according to the present invention is characterized in that a plurality of mixed gas jetting portions for jetting a mixed gas of a fuel gas and combustion air are provided with a plurality of mixed gas jetting portions. It is provided in a state of being juxtaposed in the mixed gas supply direction of the mixed gas supply unit to be supplied and in a state of ejecting the mixed gas into the same combustion space, and the mixed gas supply unit is on the lower side in the mixed gas supply direction. It is configured such that the supply pressure of the mixed gas supplied to the mixed gas jetting portion located at is higher than the supply pressure of the mixed gas supplied to the mixed gas jetting portion located on the upper side.

[0007]

According to the above characteristic construction, in the high input range where the mixed gas supply amount is large, the jetting velocity of the mixed gas jetted from each of the mixed gas jetting parts is high, but it is located on the better side in the mixed gas feeding direction. Since the supply pressure of the mixed gas supplied to the mixed gas jetting portion is lower than the supply pressure of the mixed gas supplied to the mixed gas jetting portion located on the lower side, the mixing gas from the mixed gas jetting portion located on the upper side thereof is mixed. Since the jet velocity of the gas is suppressed, the jet velocity becomes a stable jet velocity without lifting, and the mixed gas jetted from the mixed gas jet portion located on the upper side thereof does not lift but stably burns. On the other hand, although the mixed gas ejected from the mixed gas ejecting portion located on the lower side has a higher ejection velocity, the lift is effective due to the flame holding effect of the stable combustion flame of the mixed gas ejecting portion located on the lower side. Suppressed and stable combustion.

Further, in a low input range in which the mixed gas supply amount is small, the ejection speed of the mixed gas from the mixed gas ejection portion located on the lower side in the mixed gas supply direction is higher than the ejection speed at the time of the high input. Becomes slower and the jet velocity becomes stable without being lifted, and the mixed gas jetted from the mixed gas jetting portion located on the lower side of the jet velocity does not lift but stably burns. On the other hand, the mixed gas jetted from the mixed gas jetting portion located on the upper side is stably burned by the flame holding action by the stable combustion flame of the mixed gas jetting portion located on the lower side, although the jetting flow velocity thereof is considerably slowed.

[0009]

As a result, the mixed gas is a lean mixed gas having a high excess air ratio, and even if the input is wide range,
Among the plurality of mixed gas jetting portions juxtaposed in the mixed gas supply direction, the jetting flow velocity of the mixed gas jetted from any one of the mixed gas jetting portions can be set to a jetting velocity for stable combustion without lifting. , The stable combustion of the mixed gas ejected from the mixed gas ejecting part, and the stable combustion of the ejected mixed gas from the other mixed gas ejecting part by the flame holding effect of the stable combustion flame, so that the burner as a whole is stably combusted. Therefore, the turndown ratio can be increased. Moreover, since the flame temperature is lowered by burning the lean mixed gas, NOx
It has become possible to reduce the amount generated.

[0010]

EXAMPLES Examples will be described below with reference to FIGS. 1 to 3.

First, the overall structure of the gas burner will be described. Reference numeral 1 in the drawing is a burner casing, and a central vertical wall 1A is erected at the center of the burner casing 1 in the left-right direction (hereinafter, referred to as the left-right direction) in a front view, and the burner casing 1 has two left and right sides. It forms a burner space. Then, the burner section A, the mixed gas supply section B for supplying the mixed gas upward to the burner section A, and the fuel gas have the same configuration for the left and right two burner spaces, respectively. A mixing section C for mixing with combustion air is provided. Further, D shown in FIG. 3 is a fuel gas supply device D for supplying the fuel gas to the mixing sections C, C on both the left and right sides.

Next, the burner portion A will be described with reference to FIGS. The burner portion A is provided with an ejection portion forming wall body 2 having a substantially V-shaped vertical cross-sectional shape as viewed in the longitudinal direction in the upper portion of the burner space in a state where its longitudinal direction is along the left-right direction. The forming wall body 2 forms upper and lower two-stage gas ejection portions 2A and 2B, and the V-shaped inner space serves as a combustion space 3. That is, in a state in which the two mixed gas ejection parts 2A and 2B for ejecting the mixed gas supplied upward from the mixed gas supply part B into the combustion space 3 are juxtaposed in the mixed gas supply direction of the mixed gas supply part B, The mixed gas jetting section 2A located on the upper side in the mixed gas supply direction, the lower mixed gas jetting section 2A, and the mixed gas jetting section 2B located on the lower side, are provided on the upper side. Mixed gas ejection part 2B
Called.

When viewed in the longitudinal direction, the ejection portion forming wall body 2 has bottom portions 2a and lower inclined walls 2b, 2b extending in an inclined posture such that the bottom portions 2a and both side edge portions of the bottom portions 2a are separated from each other toward the upper side.
And lower step portions 2c and 2c extending outward from the upper edge portions of the lower inclined walls 2b and 2b, and an upper slope extending from the outer edge portions of the lower step portions 2c and 2c so as to be separated from each other toward the upper side. The wall 2d, 2d and the upper stepped portion 2e, 2e extending outward from the upper edge of each of the upper inclined walls 2d, 2d are formed. The outer edge of each of the upper step portions 2e and 2e is connected to the upper edge of the burner casing 1.

A mixed gas ejection hole row 4a is formed in the bottom portion 2a of the ejection portion forming wall 2 in which a plurality of mixed gas ejection holes are arranged in a row along the longitudinal direction. Further, each of the lower inclined walls 2b, 2b has four rows of mixed gas ejection holes 4b,
4c, 4d, 4e are formed in parallel in the vertical direction, and 6 rows of mixed gas ejection holes 4f, 4g, 4h, 4i, 4j, 4k are vertically arranged on each of the upper inclined walls 2d, 2d. It is formed in a state of being juxtaposed in the direction. The above-mentioned mixed gas ejection hole arrays are formed such that the mixed gas ejection holes of the adjacent mixed gas ejection hole arrays are staggered in a mutually staggered state. The diameters of the mixed gas ejection holes of each mixed gas ejection hole row are, for example, 3 mm for the mixed gas ejection hole row 4a, 4d, 4c, 4d, 4e, 4f, 4g for the mixed gas ejection hole row.
Each 4h is 1.2 mm, and each of the mixed gas ejection hole rows 4j and 4k is 1.4 mm.

That is, the lower mixed gas ejection portion 2A is composed of the bottom portion 2a and the lower inclined walls 2b, 2b on both sides, and the upper mixed gas ejection portion 2B is formed on the upper inclined wall 2 on both sides.
It is composed of d and 2d.

Next, the mixed gas supply unit B will be described with reference to FIGS. A space formed outside the jetting portion forming wall 2 (on the side opposite to the combustion space 3) by the back surface of the jetting portion forming wall 2 and the inner surface of the burner casing 1 is a mixed gas supply portion B. Mixed gas supply unit B
In the above, the partition walls 5, 5 are extended downward from the respective connection points of the outer edge of the lower step 2c and the lower edge of the upper inclined wall 2d on the back surface of the ejection part forming wall 2. By arranging, it is divided into a portion facing the lower mixed gas ejection portion 2A and a portion facing the upper mixed gas ejection portion 2B,
Further, a punching plate 6 having a large number of holes is provided on each of the lower edges of the partition walls 5 and 5.

That is, the mixed gas supply section B supplies the mixed gas flowing upward from the mixing section C described later to the lower mixed gas jetting section 2A and the upper mixed gas jetting section 2B, respectively.
Due to the flow rate suppressing action of the punching plate 6, the supply pressure of the mixed gas supplied to the lower mixed gas ejection portion 2A is lower than the supply pressure of the mixed gas supplied to the upper mixed gas ejection portion 2B. There is. Specifically, by appropriately setting the number of holes and the hole diameter of the punching plate 6, the ratio of the supply pressure to the lower mixed gas ejection portion 2A and the supply pressure to the upper mixed gas ejection portion 2B becomes 1: 2. It is done.

That is, the lower mixed gas jetting section 2A and the upper mixed gas jetting section 2B are arranged side by side in the mixed gas supply direction of the mixed gas supply section B, and the mixed gas is placed in the same combustion space 3. The mixed gas supply unit B is provided in a state of being jetted, and the supply pressure of the mixed gas supplied to the upper mixed gas jetting unit 2B located on the lower side in the mixed gas supply direction is set to the lower mixed gas located on the upper side. The pressure is higher than the supply pressure of the mixed gas supplied to the ejection portion 2A.

Next, based on FIGS. 2 and 3, the mixing section C
Will be described. The mixing section C is provided with burner casing 1 in the lower portion of the mixed gas supply section B in the burner space.
Flow-path constricting bodies 7 and 8 having a long shape and having a triangular longitudinal cross-sectional shape when viewed in the longitudinal direction, the flow-path constricting bodies being provided in a state of being arranged in parallel in two steps in the horizontal direction with respect to the inner surface of the. It is composed of a long channel separation plate 9 arranged between the channel constrictions 7 and 8 and along the left-right direction.

A fuel gas jet pipe 10 for jetting fuel gas to the mixing portion C is arranged in parallel with the lower flow path narrowing body 8, and the fuel gas jet pipe 10 has its longitudinal direction. A large number of fuel gas injection holes 10a, 10a are formed in a row along the lower flow passage narrowing bodies 8 on both sides so as to eject the fuel gas.

Reference numeral 11 in the drawing denotes a blower for supplying combustion air to the mixing section C from the lower opening of the burner casing 1 to the burner spaces on the left and right sides. A punching plate 12 for straightening is provided in the lower opening of the burner casing 1.

That is, in the mixing section C, the fuel gas ejected from the fuel gas ejection holes 10a, 10a to the lower inclined wall 8a of each of the lower flow path narrowing bodies 8 on both sides and the fuel gas The combustion air supplied from the blower 11 from the lower side is mixed, and the mixed gas flows through the narrow flow passage formed by the lower flow passage narrowing bodies 8 on both sides, and then the flow passage separation plate. 9 and 9 flow in a vortex state and in a state where the flow paths are separated on both sides, and further flow in the narrow flow paths formed by the upper flow path narrowing bodies 7, 7 on both sides. Therefore, the mixing portion C is configured so that the mixed state of the fuel gas and the combustion air in the mixed gas becomes good.

Next, the fuel gas supply device D will be described with reference to FIG. In the following description, the fuel gas ejection pipes provided in the burner spaces on the left and right sides are referred to as 10L and 10R, respectively, in the front view of the burner casing 1 for the sake of clarity.

An electromagnetic proportional valve 14 is attached to the fuel gas supply pipe 13.
The fuel gas supply pipe 13 is branched into branch pipes 13L and 13R on the lower side of the electromagnetic proportional valve 14, and the branch pipe 13L is connected to the fuel gas ejection pipe 10L and the branch pipe 13R is connected to the fuel pipe. The fuel gas supply device D is configured by connecting to the gas ejection pipes 10R and interposing the electromagnetic opening / closing valve 15 in the branch pipes 13L.

Next, a control configuration for adjusting the input amount by the fuel gas supply device D will be described.

From the maximum input to 1/3, the electromagnetic on-off valve 15 is opened, and the mixing sections C on both left and right sides are connected.
The input is adjusted by adjusting the opening of the electromagnetic proportional valve 14 in a state in which the fuel gas is supplied to C and the burners A on both the left and right sides are burned. Input is 1 /
From 3 to 1/5, the electromagnetic on-off valve 15 is closed, the fuel gas supply to the left mixing section C is stopped, and the fuel gas is supplied only to the right mixing section C to set the right burner section. The input is adjusted by adjusting the opening degree of the electromagnetic proportional valve 14 in the state of burning at A.

By adjusting the supply amount of the combustion air supplied from the blower 11 according to the input,
The excess gas ratio of the mixed gas supplied to the burner part A is 1.4.
It is a diluted mixed gas of about 1.7.

Next, with reference to FIG. 4, the construction of the warm air heater equipped with the gas burner G constructed as described above will be described.

A warm air outlet 23 communicating with an air passage 22 inside the casing 21 is provided at the lower front of the box-shaped casing 21.
Are formed in the upper part of the rear surface of the casing 21 to communicate with the air passage 22, and in the air passage 22, the gas burner G is arranged on the upstream side and the fan 25 is arranged on the downstream side. Is configured.

That is, by the blowing action of the fan 25, the convective air sucked from the air suction port 24 is mixed with the combustion gas from the gas burner G while flowing through the air passage 22.
The mixture of the convection air and the combustion gas is used as a warm air outlet 2
The discharge is made from No. 3.

[Other Embodiments] In the above embodiment, the case where the two mixed gas jetting portions 2A and 2B are arranged side by side in the mixed gas supply direction of the mixed gas supply portion B is illustrated, but three or more are provided. The mixed gas jetting section is connected to the mixed gas supply section B.
The mixed gas supply unit B is provided in a state of being juxtaposed in the mixed gas supply direction and in a state of ejecting the mixed gas into the same combustion space 3, and the mixed gas supply unit B is positioned on the lower side in the mixed gas supply direction. The supply pressure of the mixed gas supplied to the section may be higher than the supply pressure of the mixed gas supplied to the mixed gas jetting portion located on the upper side. still,
In this case, the supply pressure of the mixed gas supplied to each of the mixed gas ejection parts is adjusted by disposing a plurality of punching plates having different numbers of holes or different hole diameters.

Further, the shape of the jetting portion forming wall 2 for forming a plurality of mixed gas jetting portions can be variously changed.

Further, the number of rows of mixed gas ejection holes formed in the ejection portion forming wall 2, the arrangement of the mixed gas ejection holes in each mixed gas ejection hole row, and the shape and size of the mixed gas ejection holes. Various changes are possible.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a cutaway perspective view of a gas burner according to an embodiment of the present invention in the vicinity of a mixed gas ejection portion and a mixed gas supply portion.

FIG. 2 is a side sectional view of a gas burner according to an embodiment of the present invention.

FIG. 3 is a front sectional view of a gas burner according to an embodiment of the present invention.

FIG. 4 is a side sectional view of a hot air heater equipped with a gas burner according to an embodiment of the present invention.

[Explanation of symbols]

 2A, 2B mixed gas ejection part 3 combustion space B mixed gas supply part

Claims (1)

[Claims] 1. A plurality of mixed gas jetting portions (2A), (2B) for jetting a mixed gas of a fuel gas and combustion air are mixed gas jetting portions (2A), (2B). Are provided in a state of being juxtaposed in the mixed gas supply direction of the mixed gas supply unit (B) for supplying the gas, and in a state of ejecting the mixed gas into the same combustion space (3). Is the supply pressure of the mixed gas supplied to the mixed gas jetting portion (2B) located on the lower side in the mixed gas supply direction, the supply pressure of the mixed gas supplied to the mixed gas jetting portion (2A) located on the upper side. A gas burner that is configured to be higher than.