JP2002139204A - Spiral burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiral burner capable of adjusting fire power in a wide range from a low load to a high load by effectively preventing a back fire phenomenon and lifting of a fire. SOLUTION: A spiral burner 1 is provided, in which a spiral flow A is formed by blowing fuel gas and air from a tangential direction into a cylindrical mixing chamber 2 including a flame hole 23 where a lower end 21 is closed and an upper portion 22 forms a nozzle 26, and combustion is achieved outside the flame hole 23. In the spiral burner, a center bar 3 is installed at the center of the mixing chamber 2, in which a tip end thereof approaches the center of the flame hole 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swirl type burner which generates a swirling flow in a cylindrical mixing chamber and burns it outside the mixing chamber.

[0002]

2. Description of the Related Art There has been proposed a vortex-type burner in which a vortex flow (a swirl flow or a rotational flow) of a premixed gas of fuel gas and air is formed in a cylindrical mixing chamber and burned outside a flame opening. In this vortex-type burner, combustion is stably continued because the flow velocity is small at the center of the vortex, and mixing is fast and high-load combustion is possible because the flow velocity is large outside the vortex. For this reason, it is known that a lean air-fuel mixture having a larger excess air ratio than a normal burner can be stably burned, the generation of nitrogen oxides is small, and the burner is compact and has a high calorific value.

[0003]

In the vortex-type burner, a flashback phenomenon in which the center of the vortex becomes low pressure, the flame propagates inside the mixing chamber, and burns inside the mixing chamber, easily occurs. For this reason,
When adjusting the thermal power over a wide range from low load to high load, it is important to prevent flashback. Further, when the compactness and the high calorific value are simultaneously performed, the axial flow velocity at the flame opening exceeds the flame propagation, and the lift and the blow-off of the flame occur.

[0004] The object of the invention described in claim 1 or 2 is as follows.
It is an object of the present invention to provide a vortex burner capable of effectively preventing a flashback phenomenon and a flame lift and controlling a thermal power in a wide range from a low load to a high load. It is an object of the present invention to provide an eddy burner capable of increasing the effect of preventing lift and flashback and maximizing the stable combustion range in the air-fuel ratio of the air-fuel mixture and the combustion load of the burner. A fourth object of the present invention is to provide a vortex-type burner capable of stabilizing a flame and improving emission by complete combustion with respect to a wide range of changes in the air-fuel ratio of the air-fuel mixture and the combustion load of the burner. An object of the invention described in claim 5 or 6 is to provide a structure capable of forming a linear or planar burner in which a large number of vortex type burners are integrated at low cost.

[0005]

According to the present invention, a swirling flow is formed by blowing fuel gas and air from a tangential direction into a cylindrical mixing chamber having one end closed and a flame opening at the center of the other end. In a vortex-type burner burning outside the flame port, a center rod whose tip end is close to the center of the flame port is provided at the center of the mixing chamber.

[0006]

According to the first aspect of the present invention, the center rod functions as a stabilizer for stabilizing the swirling center of the air-fuel mixture in the mixing chamber and stabilizing the swirling flow. For this reason,
The tip of the center rod is the starting point of the inverted conical swirl flame,
A stable swirling flame can be obtained. Further, the tip of the center rod also has a function of preventing a flashback in which the flame from the flame outlet propagates into the mixing chamber. As a result, a stable vortex can be formed in the mixing chamber, flashback can be prevented, complete combustion can be performed at an air-fuel ratio with a large excess air ratio, and thermal power can be adjusted over a wide range from low load to high load. be able to.

According to a second aspect of the present invention, the tip of the center rod is
The ratio of the diameter of the front end face to the diameter of the flame outlet is 0.125 (for example, the diameter of the front end face is 1 mm: the diameter of the flame opening is 8 mm) or more,
(For example, the diameter of the tip surface is 4 mm: the diameter of the flame outlet is 8 m
m) It is within the following range, and the position of the tip surface is preferably 3 mm ± 2 mm from the center of the flame outlet. The tip surface may have any shape as long as the shape does not cause turbulence in the flow.
Further, if the tip end face is retracted by 10 mm or more from the flame outlet, the effect is reduced.

According to a third aspect of the present invention, the other end of the mixing chamber is formed as a nozzle having an apex angle of 10 to 120 degrees. Flashback) can be enhanced. Further, the swirling flow is maintained without increasing or decreasing the flow velocity in the rotating direction, and the negative pressure near the central axis becomes negative so that the flame is drawn into the nozzle, thereby increasing the effect of preventing the lift of the flame.

If the apex angle of the nozzle is 120 degrees or more, the axial flow velocity in the central portion of the swirling flow tends to fluctuate, and if it is 10 degrees or less, the swirling flow near the flame outlet weakens and the central portion of the swirling flow. , The flow velocity in the axial direction increases, and the flame easily blows off (blow-off). Therefore, the apex angle of the nozzle is 120 degrees or more.
When the range is 10 degrees, the thermal power can be adjusted in a wide range from a low load to a high load, preferably 15 degrees ± 5 degrees.
Good degree.

According to the structure of the fourth aspect, the flame outside the flame opening is protected by the flame tube, so that the mixture can be completely burned from a low excess air ratio to a high excess air ratio, and unburned gas is generated. Emission can be improved. Further, by increasing the length and diameter of the flame tube, high load combustion can be performed.

According to the fifth aspect of the present invention, since a number of mixing chambers and a flow path for supplying air and fuel gas are integrally arranged in the strip-shaped burner body, a swirl type linear shape is provided. Can be formed with parts with few burners. In the configuration according to claim 6, a large number of mixing chambers are formed in a plate-shaped burner body in a two-dimensionally dispersed manner, and the flow paths for supplying air and fuel gas are integrally provided side by side. The eddy current type planar burner can be formed with few parts.

[0012]

1 and 2 show a swirl type burner 1 according to the present invention. The swirl type burner 1 has a cylindrical mixing chamber 2 having a lower end 21 closed and a circular flame opening 23 opened at the center of an upper part 22. Have. At a lower end 21 of the mixing chamber 2, an outlet 24 for blowing a mixture of air and fuel gas into the mixing chamber 2 from a tangential direction.
And the outlet 25 are opened at an interval of 180 degrees. The mixing chamber 2 is installed vertically in this embodiment, but may be installed horizontally or diagonally, such as horizontally.

The formation of the vortex in the mixing chamber 2
One of the air blowers 4 and 25 may blow out only air, and the other may blow out only fuel gas to mix in the mixing chamber 2. In addition, the number of outlets can be appropriately selected with one or more,
A configuration in which only air is blown into the mixing chamber 2 from the tangential direction and fuel gas is blown out from the center of the lower end 21 may be employed. Furthermore, the outlets 24 and 25 may be set somewhat higher than the lower end 21.

The mixing chamber 2 has a diameter of 8 to 8 in this embodiment.
The length in the axial direction is approximately the same as the diameter. The upper portion 22 of the mixing chamber 2 is a frustoconical nozzle 26 having a vertex angle of 15 degrees. At the center of the mixing chamber 2, a center rod 3 made of a heat-resistant material fixed to the center of the lower end 21 is vertically arranged. The center rod 3 is an insulator rod having a diameter of 1.2 mm, and the upper end face 31 is set at a position about 3 mm deep from the center of the flame outlet 23. The center rod 3 may be made of a heat-resistant metal, and the nozzle 26 may be a bell mouth type.

The vortex burner 1 has an excess air ratio λ =
The air-fuel mixture of 1.6 is blown into the mixing chamber 2 from the outlets 24 and 25 and swirls, and a vortex A indicated by an arrow is generated. Eddy current A
As shown in FIG. 1, the diameter is reduced along the nozzle 26 while rotating upward, and is blown upward from the flame outlet 23. The air-fuel mixture is ignited by an igniter (not shown) and burns to form an inverted generally conical flame 4 on the flame port 23.

Above the nozzle 26, a flame tube 5 for preventing generation of unburned gas is provided.
It is 0. In this embodiment, the flame cylinder 5 is a cylinder with an open upper end, but may be a polygonal cylinder, and the upper end may have a reduced area. The height and diameter of the flame 5
It is set appropriately according to the air-fuel ratio of the air-fuel mixture and the maximum combustion load. When the flame tube 5 is omitted, the stable combustion range is narrowed, and the emission is likely to be reduced in the high load combustion or lean combustion region.

In the vortex type burner 1, when the combustion load is small and the mixture supplied to the mixing chamber 2 is small, the apex 41 of the flame 4 is attached to the upper end surface (tip surface) 31 of the center rod 3 and is inverted. Only a substantially conical flame 4 results. When the amount of combustion increases, the flow rate of the air-fuel mixture increases, and a flame 42 diffuses in the flame tube 5 as shown by a solid line. In addition, when the flame tube 5 does not exist, the flame 4 expands with the inverted substantially conical shape.

The air-fuel mixture blown from the air outlet 24 and the air outlet 25 forms a vortex whose center is stabilized by the center rod 3. Flame 4 has vertex 41 penetrating into flame outlet 23,
Since it is attached to the upper end surface 31 of the center rod 3, it is in an extremely stable state. When the excess air ratio is in the range of 1.05 to 1.9, stable combustion can be performed, and when the excess air ratio is 1.6 or more, generation of nitrogen oxides can be reduced to 0 ppm.

The size of the upper end surface 31 of the center rod 3 is preferably from 1.0 mm to 3.0 mm in diameter from the viewpoint of maximizing the stable combustion range. When the position of the upper end surface 31 is 3 mm ± 2 mm from the center of the flame port 23, the stable combustion range can be maximized. In addition, even if it protrudes flush or slightly with the flame outlet 23, it may be retracted by 5 mm or more, but if it is retracted more than 10 mm, the stable combustion range becomes narrow. The upper end surface 31 may be any one of a flat surface, a convex surface, a concave surface, and the like as long as the shape does not cause turbulence in the flow.

FIG. 3 shows a linear burner 6 in which the swirl type burners 1 are arranged in a row, and the mixing chamber 2 is arranged in a strip-shaped burner body 61. The burner body 61 is provided with an air passage 62 opening the outlet 24 and a fuel gas passage 63 opening the outlet 25. With this configuration, a linear burner including a large number of vortex-type burners 1 can be realized with a simple configuration.

FIG. 4 shows a planar burner 7 in which the vortex type burners 1 are provided in a grid pattern. As in the case of the linear burner 6, the mixing chamber 2 is provided in the burner body 71, and an air passage 72 opening the outlet 24 and a fuel gas passage 73 opening the outlet 25 are provided. ing. With this configuration,
A planar burner including a large number of vortex-type burners 1 can be realized with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a vortex burner.

FIG. 2 is a plan sectional view of a vortex type burner.

FIG. 3 is a plan sectional view of a linear burner.

FIG. 4 is a plan sectional view of a planar burner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Swirl type burner 2 Mixing chamber 3 Center rod 4 Flame 5 Flame cylinder 6 Linear burner 7 Planar burner 23 Flame opening 62, 72 Air flow path 63, 73 Fuel gas flow path

Claims (6)

[Claims] 1. A swirl flow in which a fuel gas and air are blown from a tangential direction into a cylindrical mixing chamber having one end closed and a flame opening at the center of the other end to form a swirling flow, and burn outside the flame opening. A swirl-type burner, characterized in that a center rod whose tip is close to the center of the flame port is installed at the center of the mixing chamber. 2. The swirl type premix combustor according to claim 1, wherein a tip end surface of the center rod is 10 mm from the flame port.
A swirl-type burner, which is located closer to the flame port than the retracted position and has a diameter ratio between the tip end face and the flame port in a range of 0.125 or more and 0.5 or less. 3. The vortex premix combustor according to claim 1, wherein the other end of the mixing chamber has an apex angle of 10 degrees to 1 degree.
An eddy current burner characterized by having a 20 degree nozzle. 4. A vortex-type burner according to claim 1, wherein a flame tube is coaxially provided outside the mixing chamber. 5. A swirl type burner according to claim 1, which is arranged in a strip-shaped burner body,
A linear burner in which an air flow path and a fuel gas flow path connected to each mixing chamber are arranged in the burner body. 6. An air flow path and a fuel gas, wherein the swirl type burner according to any one of claims 1 to 4 is formed in a plate-shaped burner body in a dispersed manner and connected to each of the mixing chambers with the burner body. A planar burner with a flow path arranged side by side.