JPS587886B2 - liquid fuel combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid fuel combustion method comprising an ultrasonic atomizer that utilizes the liquid fuel atomization effect of an ultrasonic vibrator.

The liquid atomization effect of ultrasonic transducers is well known.

The particle diameter of the electrostrictive liquid fuel atomized by the ultrasonic atomization device using such an ultrasonic vibrator is relatively small, about 10 μm, and is large enough to be combusted.

However, when these atomized particles pass through the flame nozzle of the burner, they collide with and are captured by the flame nozzle and its surroundings, and these particles tend to aggregate and form droplets, forming local areas of liquid combustion. This caused combustion to deteriorate.

In addition, even though the particle size as mentioned above is about 10μ, there is variation, and particles with sizes ranging from 5μ to 25μ or 30μ are distributed, so the larger the particle size, the more likely it will adhere to the area around the flame opening. This caused deterioration of flammability.

The object of the present invention is to eliminate the above-mentioned drawbacks of the conventional methods and to provide a combustion method that provides uniform flame distribution and good combustibility equivalent to that of gaseous combustion.

By the way, even if fuel particles adhere to the flame port when passing through the flame port of the flame port plate, if they are instantaneously vaporized, the liquid combustion state can be avoided.

For this purpose, the temperature of the burner port plate should be set to a high value.

However, if the temperature of the burner plate is too high, the combustion heat of the fuel will be absorbed by the burner plate, which is not good for thermal efficiency and is also undesirable from the viewpoint of heat resistance and durability of the burner plate. do not have.

The inventors of the present invention have found through experiments that the optimum temperature range for such a flame port plate is approximately 400 to 600°C.

On the other hand, since the combustion heat of the fuel is used to heat the burner plate, in order to maintain the temperature of the burner plate within the above range, a portion of the fuel calorific value must be supplied to the burner plate. There must be.

In order to show this relationship, the flame port load factor, that is, the effective area of the flame a plate divided by the combustion calorific value (combustion amount) of the entire flame port plate, in other words, the calorific value of the fuel per unit effective area and the flame The experimental results of the relationship with the temperature of the mouth plate are shown in Figure 1.As is clear from the figure, in order to make the temperature of the mouth plate about 400 to 600°C, the mouth load rate must be about 3.0 to 0.5 koal. /mm2・
The condition is that it is within the range of hr.

Note that the above effective area of the flame port plate does not refer to the total area of each flame port area of the flame port plate, but refers to the area of the flame port plate where the flame is formed, and the total area of each flame port area. It is natural that it is larger than .

Further, the thickness of the burner port plate, that is, the depth of the burner port, is an important factor in heating and vaporizing the fuel particles passing through the burner port from the surroundings.

In other words, during so-called backfire-like combustion, where the base of the flame approaches the burner surface, the burner plate is often heated by the radiant heat of the flame, so in order to keep the burner plate at a high temperature, the depth of the burner hole must be It's good to have some depth.

Of course, if the thickness of the burner port plate is too thick, a large amount of heat absorption by the burner port plate will be lost.

The diameter of the fuel particles passing through the flame nozzle also requires heat absorption time within the flame nozzle, that is, the depth of the flame nozzle within a certain range, depending on the amount of heat absorbed until vaporization.

Regarding the diameter of the flame port of the flame port plate, it is generally said that the extinguishing distance of liquid fuel is 1 stage, and it is said that if the diameter is less than this, backfire will not occur through the flame port. Therefore, it is necessary to set it to 1 mm or less.

From this point of view, as a result of experiments on the depth of the flame nozzle, the fuel particle diameter at the initial stage of passage through the flame nozzle, and the flame mouth plate temperature, as shown in Fig. 2, the fuel particle diameter was 5 to 30μ, and the flame mouth plate temperature was 400 to 400μ. 60
It has been found that in order to be in the range of 0°C, in addition to the above-mentioned burner port load factor, it is necessary that the burner port depth is in the range of 0.2 to 3 mm.

In this way, in the present invention, by specifying the flame port of the flame port plate from the depth and the flame port load factor, the temperature of the flame port plate can be maintained at an appropriate value, and the fuel particles can be kept as low as possible without turning into droplets. It provides good combustibility when vaporized.

Embodiments of the present invention will be described below with reference to FIG. 3 and subsequent figures.

However, in the following examples, the flame outlet load rate is approximately 3 koa.
l/mm^・hr and the depth of the flame mouth was 3.0 mm.

In Fig. 3, 1 is a fuel tank, 2 is a constant oil level regulator, and 3 is a fuel tank.
In the oil tank, the oil level of the fuel supplied from the fuel tank 1 is controlled to be constant by a constant oil level regulator.

4 is an ultrasonic atomizer with a built-in ultrasonic vibrator, and oil tank 3
The liquid fuel in the oil tank 3 is disposed at the bottom of the oil tank 3, and the liquid fuel in the oil tank 3 is turned into fine particles by the atomization effect of the ultrasonic vibrator.

5 is a blower, 6 is a guide tube for a mixture of premixed particulate heating material generated in the oil tank 3 and a part of the air sent from the blower 5, and 7 is a burner downstream of the burner port plate 8. Nine combustion chambers are formed.

Reference numeral 8a denotes a slit-shaped multi-hole nozzle provided on the nozzle plate 8.

The conditions of this flame port 8a are determined as described above.

Reference numeral 10 denotes an air hole provided in the wall of the burner 7, through which the residual air supplied from the blower 5 is introduced into the combustion chamber 9 as secondary air.

Therefore, the fuel supplied from the fuel tank 1 is atomized by the ultrasonic atomizer 4 in the oil tank 3, mixed with air from the blower 5, and guided into the combustion chamber 9 through the flame port 8a of the flame port plate 8. .

At this time, the air-fuel mixture is combusted by an ignition device (not shown), and the combustion is promoted by secondary air introduced from the air hole 10.

After ignition, combustion flame continuously blows out from the flame port 8a, resulting in continuous combustion.

As mentioned above, the flame port 8a has a flame port load rate of approximately 3 koal/mm.
Since the flame outlet depth l is set to 3.0 mm, the temperature of the flame outlet plate 8 is maintained at approximately 400°C from Fig. 1, and the fuel particles collide with the flame outlet plate 8 around the flame outlet 8a. However, from Figure 2, it can be seen that the flame outlet 8
It has been found that even if the fuel particles flowing through a have a large diameter of about 23μ, they are sufficiently vaporized by receiving radiant heat from the inner circumferential surface of the flame port 8a. I understand what is shown.

At this time, the root of the flame approached the surface of the flame outlet 8a and separated from the inner circumferential surface of the flame outlet 8a, heating the flame outlet 8a with radiant heat.

FIGS. 4 and 5 show modifications of the flame outlet shape according to the present invention, and FIG. 4 shows a case where a mesh-like flame outlet net 11c is sandwiched between two flame outlet plates 11a and 1Ib, FIG. 5 shows a case where a large number of burner ports 13 are formed by punching the burner port plate 12.

In all of these cases, the depth of the burner port and the load rate of the burner port are determined in the same manner as in the previous embodiment, and the effects are also the same.

As explained above, according to the present invention, the fuel particles colliding around the flame nozzle are heated and vaporized by the flame nozzle plate which sufficiently recovers heat from the flame, and the fuel particles flowing through the flame nozzle are also exposed to the high temperature atmosphere inside the flame nozzle. Since the gas is maintained at an appropriate depth and is sufficiently vaporized, the combustion has good properties equivalent to gaseous combustion and the flame distribution is uniform.

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between the burner port temperature and the burner port load factor, Fig. 2 is a graph showing the relationship between the burner port depth, the burner port temperature, and the fuel particle size, and Fig. 3 is a graph showing the relationship between the burner port depth, the burner port temperature, and the fuel particle size. FIGS. 4 and 5 are schematic configuration diagrams showing one embodiment of the present invention, and are cross-sectional views showing modifications of the burner port and the burner port plate according to the present invention. 4... Ultrasonic atomization device, 7... Burner, 8, 11a to 11c, 12... Flame mouth plate, 8
a, 13... Flame mouth.

Claims (1)

[Claims] 1. In a liquid fuel combustion method in which liquid fuel is atomized using an ultrasonic vibrator and combusted in a burner 7, the burner port plate 8 of the burner 7 has a diameter of 1 mm or less and the burner port 8a has a diameter of 1 mm or less. The depth is in the range of 0.2 to 3.0 mm, and the relationship between the fuel calorific value in the burner 7 and the effective area of the burner port plate 8 is such that the burner port load factor is 0.
5-3 koal/mm2. A liquid fuel combustion method characterized in that the liquid fuel combustion method is set to fall within a range of hr.