JPS5913641B2 - combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion device having a burner using swirling airflow.

Typical burners that have been conventionally used as burners that use swirling air flow are those shown in FIGS. 1 and 2.

In Figure 1, a reverse flow of combustion gas is created in the combustion chamber to improve the mixing of air and fuel and the stability of the flame.

That is, in FIG. 1, 1 is a combustor wall, 2 is an air swirler, 3 is a fuel injection nozzle, 4 is a combustion chamber, and 5 is an outlet thereof.

A general feature of such a combustor is that an air flow as shown by arrow B is generated within which a flame as shown is formed.

Such combustors are widely used in the industrial field, but in order to achieve the sufficient effect of swirling air, high blowing pressure (
It has drawbacks such as requiring a water column of several tens of millimeters or more and producing large combustion noise.

The structure shown in Figure 2 is commonly used in so-called small gun-type oil burners, and this type of burner is most commonly used in household oil water heaters.

In this figure, each number can be considered to have almost the same function as in FIG. 1.

However, since the blowing pressure of the blower used in the air swirler 2 is generally low, the ability to swirl the air is low, and at most it has the effect of extending the mixing distance of air and fuel and slightly promoting combustion. Therefore, it is said that such burners have the disadvantage that some unburned substances are emitted when petroleum or the like is used as fuel.

In addition, as a modification of these burners, means are taken to generate swirling airflow on the combustor wall surface, and the swirling airflow generated by this means attempts to advance combustion while preventing soot from adhering to the combustor wall. Some ideas have been proposed.

In this type of burner, a large amount of soot is generated in the center of the combustion chamber, that is, in the region where the swirling flow is weak, which is unacceptable from the standpoint of achieving good combustion. There isn't.

This invention was made in view of these points, and it is possible to make the flame more compact and prevent soot from adhering to the vessel wall, as well as to prevent the generation of soot in the flame by using swirling airflow. This paper proposes a burner structure.

To explain this invention using figures, FIGS. 3 and 4 are schematic illustrations of one embodiment of this invention.

In the figure, 100 indicates a wall of the combustion chamber 101, 100a indicates a wall above the swirling air supply means, and 100b indicates a wall below.

102 is an outer wall of the combustion distribution chamber, 103 and 104 are flange portions for connecting and connecting the lower wall portion 101 of the combustion chamber and the wall 102 of the fuel distribution chamber, and 103 is integral with the lower wall portion 101;
are formed integrally with the wall 102.

105 is a screw for perfecting the connection between the flanges 103 and 104, and 106 is a screw for the flanges 103 and 104.
A gasket interposed between 4 and 121 is a fuel distribution chamber, 122
110 is a combustion air inlet, 107 is a wall of the annular air supply chamber 108, 109 is an air supply pipe, and 120 is provided at the bottom of the combustion chamber. 140 is a fuel inlet provided on this burner plate; 130 is a burner plate fixed to the combustion chamber wall 100 at equal intervals in the circumferential direction by welding, etc.; a part of the combustion air is directed toward the center of the combustion chamber 101; This is a dogleg-shaped guide board.

FIG. 5 shows the flow in the direction parallel to the central axis of the combustion chamber when the guide plate 130 for supplying part of the combustion air in the direction of the central axis of the combustion chamber is not provided. 301 is a component directed downward from the combustion air inlet 110, and 301 is a component directed upward.

As a result of our investigation, the inventors found that in burners with such a structure, regardless of the height at which the combustion air inlet 110 is provided, the diameter of the combustion chamber, etc., the diameter is always smaller than the diameter of the combustion chamber (d in the figure).
It was discovered that a region was formed in which the cylindrical airflow (denoted as o) headed toward the outlet (upward) of the combustion chamber, and at the same time, the existence of flows 302 and 303 near the central axis flowing into the region was confirmed.

In such a combustion device, there is a lack of air near the central axis, so unless the reverse flow 302 is strengthened (for that purpose, it is necessary to increase the jet of air from the inlet 110), the combustion air will be close to the theoretical air amount. As the value increases, the generation of soot in the flame near the central axis increases, and if you try to strengthen the reverse flow, it becomes necessary to increase the blowing pressure to supply combustion air, which may result in an increase in noise. There is.

FIG. 6 shows the shape of the flame of the burner shown in FIG.

The fuel that exits the fuel inlet 140 first forms a dark blue flame 500 near the burner plate 120, and further forms a light blue flame 501 above (on the combustion chamber outlet side) (when the primary air amount is small) , flame 500 is not formed and flame 50
(only 1).

As the amount of combustion air approaches the theoretical air amount, a thin yellow flame 502 due to lack of air is observed inside the flames soo and soi (near the central axis).

This yellow flame 502 causes incomplete combustion.

The guide plate 130 solves this problem, and the guide plate 130 works to strengthen the flow component 304 of the air that heads toward the vicinity of the central axis of the combustion chamber after exiting the combustion air inlet 110, so that it is sufficient for the flame 502. This provides sufficient air to promote complete combustion.

(Figure 1 shows the state of the flame when the guide plate 130 is provided.

) In addition to the above-mentioned function, the guide plate 130 also has the function of supplying a large amount of air to the flame 501.

As shown in FIG. 6, when the guide plate 130 is not provided, an air flow 301 exists surrounding the flames 501 and 502, and a part of this air is emitted outside the combustion chamber without contributing to combustion at all. However, by providing the guide plate 130, moderate air turbulence occurs near the air inlet 110, improving the mixing of unburned components of the fuel and air, and complete combustion can be achieved with a so-called low blowing pressure of several millimeters of water column. It completely prevents the generation of eels and soot.

That is, the guide plate 130 has the function of promoting sufficient utilization of combustion air.

If this guide plate 130 is large, the swirling component of the combustion air, which is a characteristic of this combustion device, will be weakened, and the flow component 300 of the air toward the burner plate 120 will be weak, so the flame will be stable on the bottom plate of the combustion chamber. If the guide plate 130 is too small, it will cause noise during combustion, and if the guide plate 130 is too small, it will not be able to perform the above-mentioned function satisfactorily.

If the size of the guide plate 130 is selected with this point in mind, there are no particular restrictions on the shape of the guide plate 130, as long as a part of the combustion air is directed to the vicinity of the combustion chamber. The effect can always be expected.

Further, the number of guide plates 130 is determined depending on the correlation with the size thereof, and generally, when the guide plates 130 are large, the number thereof is small, and when the guide plates 130 are small, the number may be increased.

In addition, in the above embodiment, the diameter of the combustion chamber 101 is the same across the top and bottom, but the diameter of the combustion air input section and the upstream side of the combustion air input section is different from the combustion air input section. Even if the present invention is applied to a combustion chamber that is smaller than the downstream diameter by /J, the same effect as in the above embodiment can be obtained.

As described above, the combustion apparatus according to the present invention can always achieve stable combustion over a wide range of air-to-fuel ratios with low air supply pressure, and has the effect of preventing soot generation.

[Brief explanation of drawings]

1 and 2 are schematic illustrations of a conventional burner using swirling air, FIG. 3 is a longitudinal sectional view showing an embodiment of the present invention, and FIG.
The figure is a cross-sectional view taken along the line IV-IV in Figure 3, taken in the direction of the arrow, Figure 5 is a diagram showing the flow of air when no combustion air guide plate is provided, and Figure 6 is a diagram showing the flow of combustion air. FIG. 7 is a diagram showing the shape of the flame when no guide plate is provided, and FIG. 7 is a diagram illustrating the shape of the flame when the combustion air guide plate is provided. In the figure, 101 is a combustion chamber, 110 is a combustion air inlet, 108 is an air supply chamber, 120 is a burner plate, 130 is a guide member, and 140 is a fuel inlet. It should be noted that the same reference numerals in the drawings indicate corresponding parts.

Claims (1)

[Scope of Claims] 1. Means for injecting combustion air so as to form a swirling flow along the peripheral wall of a cylindrical combustion chamber, and a means for injecting combustion air so as to form a swirling flow along the circumferential wall of a cylindrical combustion chamber; and a fuel injection means for injecting air into the combustion chamber, the guide member having a tip extending to the vicinity of the center in the radial direction of the combustion chamber in order to supply a part of the combustion air to the center in the radial direction of the combustion chamber. A combustion device characterized by being provided with. 2. The combustion air input portion of the combustor and the diameter upstream of the combustion air input portion are smaller than the diameter downstream of the combustion air input portion. combustion equipment. 3. The combustion device according to claim 1 or 2, wherein a plurality of guide members are provided and the plurality of guide members are provided at equal intervals in the circumferential direction. 4. The combustion air input means has an annular air supply chamber surrounding the outside of the combustion chamber, and a combustion air input port that communicates the air supply chamber with the combustion chamber. A combustion device according to any one of claims 1 to 3. 5. Claim 1, characterized in that the fuel input means for inputting fuel or a mixture of fuel and air has a burner plate, and the burner plate serves as a bottom plate of the combustion chamber. The combustion device according to any one of items 1 to 4.