JPS6143601B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides prevention of flashback to the fuel supply section in the event that a burner cap or the like is dislodged, and a safety measure accompanying this prevention.

With gas burners, backfire is mainly prevented at the flame hole, and even if a backfire were to occur, the backfire would reach the nozzle and only cause overheating of the burner; if the gas is turned off, the flame will be extinguished and there will be no major problem. Hateful. However, in the case of a device that vaporizes and premixes kerosene, etc., if a backfire occurs in the fuel supply section, special means to extinguish the fire and safety measures against heat are required, and some kind of absolute measures are required.

In addition, in devices that vaporize and burn kerosene, etc., a high primary air ratio and high mixed gas temperature are required due to the properties of kerosene gas. Therefore, even though the yellow flame limit and the lift limit are very close, backfire is likely to occur, and there is a strong possibility that it will return to the fuel supply section.

Therefore, in a kerosene vaporizing burner, a constriction section may be provided between the vaporizing chamber and the mixing chamber to increase the differential pressure and eliminate backfire into the vaporizing chamber. On the other hand, in the burner flame hole, it is necessary to increase the pressure upstream of the flame hole to prevent backfire, so a large pressure difference is required between the flame hole and the vaporization chamber, which requires a large fan capacity, which can also cause noise. . Also, when the burner cap floats, the flame enters the throttle and continues combustion there, causing overheating, which is dangerous.

Note that some gas burners have a punching plate inserted into the mixing chamber, but this is intended to equalize the supplied gas and is difficult to prevent backfire.

Therefore, in this case, we are trying to deal with this by using the idea of making the existence of flame impossible (extinguishing the flame).

An embodiment of the present invention will be described below with reference to the accompanying drawings.

1 is a burner cap consisting of a flame hole 3 having a sufficient length and a flame holding part 2 having a concave groove spaced apart from the outlet end of the flame hole, and has a slight arc 4 on the inside of the top plate part. Reference numeral 5 denotes a burner body for vaporizing and mixing the air-fuel mixture, and the burner is constructed by placing the cap 1 on a burner head 6.

Reference numeral 7 denotes a rectifying gap formed by the burner cap 1 and the inner wall of the burner body 5, which has a constant gap around the entire circumference and forms a rectifying space for supplying the mixed gas to the flame hole 3.
This constitutes a substantial combustion control space and determines the combustion range.

Reference numeral 8 denotes a backfire prevention plate made of a punched plate or the like having a large number of small holes 9, and is inserted into a mixing chamber 14 divided by a rectifier plate 11 that narrows the inner space of the burner body 5 to prevent backfire from the bottom of the burner cap 1. It is separated into a mixed gas supply space 10 formed by the prevention plate 8 and a mixing chamber 13 below the flashback prevention plate 8. this space 10
is preferably 2 mm or less; if it is 3 mm or more, the objective may not be achieved depending on the mixing ratio. The small holes 9 are smaller than the flame extinction distance, 0.8φ for kerosene vapor and 1.0φ or less for gas fuel, that is, 1.0φ or less, and the total area of the small holes is larger than the total area of the flame holes 3. (for slit grooves, the width is less than 0.6 mm and 0.8 mm, respectively) to serve as a backfire prevention plate. A throttle rectifier plate 11 is provided with a throttle opening 12 at an appropriate gap from the flashback prevention plate 8, and a vaporization chamber 15 is formed below the plate. This aperture 12 projects into the mixing chamber 13 and has a curvature toward the vaporizing chamber to reduce resistance.
The area of the orifice should be such that it can rectify the vaporized air-fuel mixture mixed turbulently in the vaporization chamber and change the flow almost upward, and should be at least larger than the aperture ratio of the flashback prevention plate 8, and It is better to make it as large as possible to reduce the loss.

Reference numeral 17 denotes a heater attached to the bottom of the burner body 5, which heats the burner section and heats the mixture of liquid fuel and air that is ejected from the fuel body supply pipe 16 through its inner wall by heating the vaporization chamber during ignition. This gives it the function of vaporizing the fuel.

In operation, the particulate or atomized liquid fuel and the primary air for combustion collide with the wall of the vaporization chamber through the supply pipe 16, and are vaporized by the heat of the heater 17. The vaporized fuel and the heated air are turbulently mixed while being bounced off the wall, directionally collide with the throttle rectifier plate 11, and are rectified by the throttle port 12 and supplied to the mixing chamber 13. Since the purpose of this throttle opening 12 is only to rectify (upward) the air-fuel mixture, it is desirable that it be as large as possible within the effective range.
Consideration is given to reducing pressure loss. The rectified air-fuel mixture exits from the throttle opening 12, is rapidly expanded and mixed, and is supplied to the rectification gap 7 through the small hole 9 of the flashback prevention plate 8, and then to the flame hole 3.
It blows out and burns. Here, the openings of the flashback prevention plate 8 and the throttle rectifier plate 11 are set to be larger than the flame hole area, preferably at least twice the area from the viewpoint of pressure loss. The rectifying gap 7 is set to be smaller than the area of the flame hole, forms a high pressure region here, has a rectifying effect and an effect of preventing backfire from the flame hole, and serves as a substantial combustion regulating section. The air-fuel mixture, which has been increased in pressure and speed, is ejected through the flame hole while reducing its speed, obtaining a portion of secondary air, which is held and combusted by the flame holding section 2. In other words, while increasing the pressure in the supply space 10, the resistance due to the throttle plate 11 and flashback prevention plate 8 is reduced, and care is taken not to excessively increase the fan capacity. By holding and burning the fuel, yellow flame, lift, and backfire are prevented and stable combustion is achieved over a wide adjustment range. If a backfire occurs from the flame hole 3 during use, or if the burner cap comes off, the flame returns to the flashback prevention plate 8 and burns in the small hole 9. However, since the small hole 9 is set below the extinguishing distance, no backfire occurs from this point and the flame does not return to the supply section.

If the burner cap is dislodged, the flame forms on the flashback prevention plate 8 and burns, which can be visually confirmed and safely extinguished by stopping the device. However, if the burner cap were to float, the flame would return to the flashback prevention plate 8 and burn in the same way. If the burner cap 1 returns to normal under this condition, the flame will generally continue to burn in the supply space 10 formed by the cap 1 and the flashback prevention plate 8, causing the burner to overheat and become dangerous. At this time, there are no abnormal sounds such as combustion sounds, so you may not notice it. However, in this case, this distance is set so that no flame is formed in this space, so the flame is not formed here but disappears. However, if this gap is set to more than 2mm, a flame may be formed depending on the mixture ratio.
If it is 3 mm or more, a flame will almost be formed at a mixing ratio that achieves good combustion in the flame hole. These gaps vary depending on the amount of combustion gas, and may become wider as the amount of gas increases, and the gaps may be determined according to the required amount of combustion. However, if the thickness is set to 2 mm or less, there is no fear of flame formation and stability is achieved even at low combustion rates. Therefore, if the burner cap is properly placed by setting the gap according to the purpose as described above, no flame will be formed in the space 10, so it is safe from backfire from the flame hole.

Next, FIG. 2 shows another embodiment in which the burner cap 1 is brought into contact with the flashback prevention plate 8 to limit the supply space 10.
This makes it difficult to recognize the presence of flames. Also, the small holes 9 formed in the flashback prevention plate 8 are gathered around the periphery (in this case, the total small hole area should be larger than the total area of the flame holes...it doesn't need to be twice) to speed up the flow and extinguish the flame. being effective.

Note that the prevention plate shown in FIG. 2 may be used in FIG. 1.

These ideas can also be applied to gas combustion, and are particularly effective in premix combustion.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention applied to a kerosene vaporizing burner, and FIG. 2 is a partial view of another embodiment. 1...burner cap, 2...flame holding part, 3...
Flame hole, 5... burner body, 6... burner head.

Claims (1)

[Claims] 1. A burner cap mounted on a burner body, in which small holes with a diameter smaller than the flame extinction distance are arranged in the mixing chamber so as to have openings larger than the total flame hole area. A fire prevention plate is provided, and the backfire prevention plate and the bottom surface of the burner cap are opposed to each other, and the gap therebetween is
A burner configured with a gap so narrow that no flame can form. 2. The burner according to claim 1, wherein the flashback prevention plate and the bottom of the burner cap are partially brought into close contact with each other.