JP7037176B2 - Premixed gas burner - Google Patents

Description

The present invention relates to a premixed gas burner in which combustion air and fuel gas are premixed and supplied to a burner head so that combustion is performed while injecting a premixed gas. More specifically, the present invention relates to a premixed gas burner. It relates to a premixed gas burner with improved mixing properties of combustion air and fuel gas.

As described in Japanese Patent No. 2950196, there is known a premixed gas burner in which combustion air and fuel gas are mixed in advance and combustion is performed while injecting the premixed gas. In the premixed gas burner described here, two throttle members are arranged so as to face each other in a burner duct that allows combustion air to flow toward the burner head, and a substantially Venturi-shaped gas mixer portion is formed in the central portion. .. This throttle member has a portion parallel to the burner duct by bending at the throttled end, and a diffuser having a gentle spreading angle (about 5 to 10 degrees) is provided on the downstream side thereof. A portion surrounded by the throttle member and the wall surface of the burner duct is used as a gas chamber, and a plurality of small holes are opened as gas ejection portions on the parallel surface of the throttle member. In the premixed gas burner having the above configuration, the combustion air supplied from the upstream end of the burner duct has the fuel gas supplied from the gas ejection part for increasing the flow velocity and decreasing the pressure at the portion where the throttle member is arranged. It is effectively stripped from the parallel planes and efficiently premixed with the combustion air.

In a premixed gas burner that mixes combustion air and fuel gas in advance and injects premixed gas at the burner head to burn, it is necessary to sufficiently mix the combustion air and fuel gas before the burner head. be. If the distance from the mixing part of the combustion air and the fuel gas to the burning part is long, the fuel gas will be uniformly dispersed in the premixed gas, but if the length of the mixing promotion part is lengthened, combustion will occur. The equipment becomes large. In the premixed gas burner described above, the flow path of the combustion air is narrowed to increase the flow velocity of the combustion air, thereby obtaining the action of sucking the fuel gas injected from the gas injection section, thereby obtaining the combustion air and the fuel. The mixture of gas is improved. This makes it possible to shorten the length of the mixing promotion section that mixes the combustion air and the fuel gas, but even so, there may be a portion where the proportion of the fuel gas is small in the central portion of the combustion air flow. In order to reduce the size and space of the device, it is desired to further promote the mixing of combustion air and fuel gas, and a structure capable of further improving the mixing property has been studied.

Japanese Patent No. 2950196

The problem to be solved by the present invention is the mixing property of combustion air and fuel gas in a premixed gas burner in which a premixed gas in which combustion air and fuel gas are mixed in a burner duct is supplied to a burner head for combustion. Is to improve.

According to the first aspect of the present invention, a fuel gas pipe for supplying fuel gas is connected to the burner duct that sends the combustion air from the blower to the burner head, and the fuel gas pipe is passed through the combustion air sent through the burner duct. In a premixed gas burner in which the premixed gas is injected from the burner head to burn as a premixed gas by mixing the fuel gas to be sent, the cross-sectional area of the flow path of the combustion air flowing in the burner duct is inside the burner duct. An inner plate of the throttle that reduces the size of the fuel gas and an outer plate of the throttle that is arranged so as to open and overlap the injection gas flow path, which is a gap for flowing fuel gas, are installed on the outside of the inner plate of the throttle. By installing a cylindrical member that maintains the cross-sectional area of the flow path in the burner duct in a reduced state, and by installing a divergent member that expands the flow path area in the burner duct further downstream of the cylindrical member, the inside of the burner duct is installed. An annular space is formed on the outside of the cylindrical member, the fuel gas pipe is connected so that the fuel gas can be supplied to the annular space, and the injection gas flow path is the combustion air flow in the burner duct. It is oriented in the direction of the central axis, and is characterized in that the fuel gas is injected from the injection nozzle provided at the tip of the injection gas flow path on the extension line of the injection gas flow path.

The flow velocity of the combustion air flow increases along the inside of the inner plate of the throttle due to the reduction of the flow path area, and the flow velocity increases when the tip of the inner plate of the throttle is exceeded. In this part, a negative pressure is generated in the combustion air flow, and the action of sucking the gas around the periphery occurs. Further, the fuel gas flow flowing in the injection gas flow path sandwiched between the throttle inner plate and the throttle outer plate is injected on the extension line of the injection gas flow path when injecting from the injection nozzle, so that it is for combustion. The gas is injected toward the central axis of the air flow, and flows in the direction of mixing with the combustion air flow flowing in the central portion of the burner duct.

Even in the injection gas flow path 5, even if the throttle inner plate and the throttle outer plate are at the same distance in the injection gas flow path, the throttle inner plate and the throttle outer plate are tapered, so that the flow in the injection gas flow path The cross-sectional area of the road will be reduced, and the flow velocity of the fuel gas injected from the injection nozzle will increase. Since the fuel gas having an increased flow velocity collides with the combustion air flow, the combustion air and the fuel gas collide violently, and the mixing of the two is further promoted in the mixing portion.

Further, the fuel gas is injected from the injection nozzle after flowing in the annular space on the inner peripheral edge of the burner duct, and the flow path area at the injection nozzle is smaller than the annular space on the inner peripheral edge of the burner duct. The flow of the fuel gas is made uniform, and the fuel gas having no shading is injected from the annular injection nozzle, so that the distribution of the fuel gas in the premixed gas flow is made more uniform.

By implementing the present invention, the mixing property of the combustion air and the fuel gas is improved, and the distance from the mixing portion of the combustion air and the fuel gas to the combustion portion can be shortened, so that the combustion device can be miniaturized. be able to.

Cross-sectional view of the combustion air and fuel gas mixing part of the premixed gas burner in which the present invention is carried out. Flow chart of the whole premixed gas burner carrying out this invention

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a combustion air and fuel gas mixing portion of a premixed gas burner carrying out the present invention, and FIG. 2 is a flow chart of the entire premixed gas burner carrying out the present invention.

The premixed gas burner of the present invention injects fuel gas into the burner duct 1 through which the combustion air flows, and sends the premixed gas in which the combustion air and the fuel gas are mixed to the burner head 2. The burner duct 1 is a pipe having a large diameter for flowing combustion air sent from the blower 9, and in the middle of the burner duct 1, a concentric truncated cone-shaped diaphragm inner plate 3 having an inlet surface and an outlet surface opened is formed. The diaphragm outer plates 4 are installed so as to be overlapped with a slight gap. The aperture inner plate 3 and the aperture outer plate 4 have the same aperture angle, and the aperture inner plate 3 has a longer vertical length, and there is a gap between the aperture outer plate and the inner wall of the burner duct. Vacant.

The diaphragm inner plate 3 and the diaphragm outer plate 4 are aligned on the tip side, and the cylindrical member 10 is installed near the tip side of the diaphragm outer plate 4. The cylindrical member 10 is concentric with the burner duct 1 and has a smaller diameter than the burner duct 1, and a conical trapezoidal member that expands the flow path area is installed further ahead of the cylindrical member 10. .. The conical trapezoidal member on the front side is connected to each of the cylindrical member 10 and the inner surface of the burner duct, and an annular space is formed between the cylindrical member 10 and the burner duct 1. The fuel gas pipe 8 for supplying the fuel gas is connected so that the fuel gas is introduced into the annular space.

The space sandwiched between the throttle inner plate 3 and the throttle outer plate 4 is used as the injection gas flow path 5, and the space between the tip of the throttle inner plate 3 and the tip of the throttle outer plate 4 is set as the injection nozzle 7, and the fuel gas is the injection gas flow. It passes through the path 5 and is sprayed from the injection nozzle 7. When the inclined surfaces of the throttle inner plate 3 and the throttle outer plate 4 are made parallel to each other, the distance between the throttle inner plate 3 and the throttle outer plate 4 does not change in the injection gas flow path 5, but the injection gas flow. Since the cross-sectional area of the injection gas flow path 5 becomes smaller toward the downstream side in the path 5, the flow velocity of the fuel gas increases. When the fuel gas flowing in the injection gas flow path 5 enters the annular space in the burner duct, it flows in the direction opposite to the combustion air flowing on the central axis side of the burner duct and then in the injection gas flow path 5. And is injected on the extension line of the injection gas flow path 5. Since the injected gas flow path 5 is directed toward the central axis of the burner duct 1, the fuel gas is injected toward the center of the burner duct 1.

In this case, the flow path is narrowed by the injection nozzle 7 and the pressure rises, so that the flow of fuel gas in the annular flow path on the upstream side of the fuel gas flow is made uniform. By making the fuel gas flow in the annular flow path uniform, the fuel gas injected from the injection nozzle 7 is not biased, and the mixed state with the combustion air becomes good.

Combustion air sent from the blower through the burner duct 1 flows along the inner surface of the throttle inner plate 3, and the cross-sectional area of the flow path through which the combustion air flows by the throttle inner plate 3 decreases, so that the combustion air Flow velocity increases. The cross-sectional area of the flow path of the combustion air is reduced at one end by the throttle inner plate 3, and the flow path is expanded after the reduced state is maintained at the portion of the cylindrical member 10.

The combustion air flow whose flow velocity is increased by the throttle inner plate 3 generates a negative pressure region on the tip side of the throttle inner plate 3, and sucks and mixes the fuel gas flow flowing around the negative pressure region. Further, since the flow direction of the fuel gas flow injected from the injection nozzle 7 is directed toward the central axis of the combustion air flow, the fuel gas flow injected from the injection nozzle 7 enters the combustion air flow and is used for combustion. Mix with air.

The premixed gas in which the combustion air and the fuel gas are mixed is sent to the burner head 2 at the tip of the burner duct 1. The burner head 2 installed downstream of the burner duct 1 is formed by processing a punching metal into a cylindrical shape and covering the periphery with a metal knit. The metal knit is made by knitting metal fibers with high heat resistance, and it is welded to the punching metal to prevent the metal knit from rising. Punching metal is made by making a large number of holes in a metal plate, and by covering the outside of the punching metal with a metal knit, the premixed gas is ejected through the holes of the punching metal and through the gaps between the fibers of the metal knit.

A pilot burner 6 that generates a pilot flame is installed on the outer surface of the burner head 2 in the head portion 2 of the premixed gas burner. When the premixed gas is injected from the metal knit surface of the burner head 2 while the pilot flame is being burned by the pilot burner 6, the flame is burned on the surface of the metal knit.

When fuel gas is injected into the combustion air in the burner duct 1 to mix the combustion air and the fuel gas, it is necessary to lengthen the flow path in the burner duct in order to perform sufficient mixing only in the burner duct 1. was there. However, if the flow path in the burner duct 1 is lengthened, the combustion device becomes large. Therefore, in order to save space, the length of the flow path in the burner duct 1 is suppressed and the mixing property of the premixed gas is increased. Was desired.

In this embodiment, the flow velocity of the combustion air flow increases because the flow path area is reduced when passing through the throttle inner plate 3 provided in the middle of the burner duct 1, and the fuel gas flow is also the throttle inner plate 3. When passing through the injection gas flow path 5 formed between the throttle outer plate 4 and the throttle outer plate 4, the flow path area is reduced, so that the flow velocity of the fuel gas flow to be injected through the injection nozzle 7 at the tip of the injection gas flow path also increases. .. In the burner duct 1, since the flow path expands after being narrowed at the tip of the throttle inner plate 3, the combustion air flow spreads toward the end due to the expansion of the flow path. On the tip side of the injection nozzle 7, a negative pressure region is generated in the combustion air flow, and a flow for sucking the surrounding gas from the periphery of the combustion air flow into the combustion air flow is generated. Since the injection gas flow path 5 is directed toward the center of the burner duct 1, the flow toward the tip of the injection nozzle 7 is toward the combustion air flow flowing through the center of the burner duct. Therefore, the fuel gas flow enters the inside of the combustion air flow, and a turbulent flow is generated at the intersection of the combustion air flow and the fuel gas flow, and the combustion air and the fuel gas are mixed. As described above, the length of the mixing promoting portion can be suppressed while maintaining the combustibility of the flame, so that the space saving of the combustion device can be achieved.

It should be noted that the present invention is not limited to the embodiments described above, and many modifications can be made by a person having ordinary knowledge in the art within the technical idea of the present invention. For example, in the embodiment, the burner duct 1 has a cylindrical shape, but the same effect can be obtained by forming the burner duct 1 into a quadrangular column shape having a quadrangular cross section and forming the diaphragm inner plate and the diaphragm outer plate into a quadrangular pyramid shape. ..

1 Burner duct
2 Burner head 3 Squeeze inner plate 4 Squeeze outer plate 5 Injection gas flow path 6 Pilot burner 7 Injection nozzle 8 Fuel gas piping 9 Blower 10 Cylindrical member

Claims (1)

A fuel gas pipe that supplies fuel gas is connected to the burner duct that sends the combustion air from the blower to the burner head, and the fuel gas that is sent through the fuel gas pipe is mixed with the combustion air that is sent through the burner duct. In a premixed gas burner in which a premixed gas is injected from a burner head as a mixed gas for combustion, an inner plate of a throttle for reducing the cross-sectional area of the flow path of combustion air flowing in the burner duct and a throttle are contained in the burner duct. On the outside of the inner plate, a throttle outer plate is installed so as to open and overlap the injection gas flow path, which is a gap for flowing fuel gas, and the fuel gas pipe supplies fuel gas to the injection gas flow path. The injection gas flow path is directed toward the central axis of the combustion air flow in the burner duct, and is injected from the injection nozzle provided at the tip of the injection gas flow path. Fuel gas is injected on the extension of the gas flow path, and a cylindrical member that keeps the flow path cross-sectional area in the burner duct reduced is installed on the downstream side of the throttle outer plate. By installing a divergent member that expands the flow path area in the burner duct on the downstream side, an annular space is formed outside the cylindrical member in the burner duct, and a fuel gas pipe is used to supply fuel gas to the annular space. A premixed gas burner characterized by being connected .

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