JPH073281B2 - Liquid fuel combustion device - Google Patents

Description

TECHNICAL FIELD The present invention is an apparatus for vaporizing and burning liquid fuel, and is used in the fields of heating, hot water supply, heating, drying and the like.

2. Description of the Related Art A conventional vaporizer has a structure shown in FIG. 3 as shown in, for example, Japanese Patent Application No. 59-210801. That is, in the vaporization case 1, the lower end of the wicking body 2 is immersed in the fuel in the fuel tank 3, and the fuel oil surface of the fuel tank 3 is a substantially constant oil surface by the sealed fuel tank 4. The wicking body 2 is provided so as to include the heating element 5.

The principle of operation according to the above conventional example will be described below. Wicking body 2
Sucks the fuel from the fuel tank 3 to the vicinity of the heating element 5 by the capillary phenomenon. When the heating element 5 is energized, the fuel is vaporized due to the heat generation. This vaporized gas was sent to the burner 7 by the vaporized gas carrying air supplied from the blower 6 provided upstream of the vaporization case 1 and burned there.

Problems to be Solved by the Invention The above-described conventional configuration has a problem that the fuel vaporization amount decreases with time and the life of the combustion device is short. The reason will be described below.

The cause of the decrease in the fuel vaporization amount is caused by the tar component generated in the wicking body 2 closing the capillary tube of the wicking body 2. The tar content is a high boiling point component originally mixed in the fuel oil, or the fuel oil is produced by a high boiling point component oxidized and polymerized by oxygen in the air. It does not completely vaporize from the surface of No. 2 and turns into tar. Here, the latter high boiling point component generated by the air oxidation is particularly remarkably generated when the fuel oil is exposed to a high temperature for a long time, and when the wicking body 2 is used, the amount of vaporization with time is increased. Most of the causes
Due to this latter cause.

In the configuration of the conventional example, the heat of the heating element 5 is transmitted to the wicking body 2 around it and further to the lower side of the wicking body 2, so that the wicking body high temperature portion becomes extremely wide and is wicked up. The fuel is kept at a high temperature for a long time in the process of being sucked up before being vaporized by the wicking body 2 around the heating element, so that the above-mentioned high-boiling point component and tar formation due to air oxidation are generated. It was easy to happen. For example, when using kerosene,
The temperature at the top of the wicking body 2 is in the range of 200 to 300 ° C, but it is about 100 ° C even 10 mm below the lower end of the heating element 5.

Further, in order to prevent such a phenomenon, if the distance between the heating element 5 and the fuel oil surface is reduced with the conventional configuration, the temperature of the wicking body 2 is lowered, but the lower part of the wicking body 2 is lowered. The temperature of the fuel oil surface in which is immersed increases, and the fuel oil surface is
Since it is stationary, it is kept in a high temperature state for a long time, so that a high-boiling point component is easily generated due to air oxidation-tarification.

Tar formation due to air oxidation of the fuel oil described above is likely to occur, and the decrease in vaporization amount due to this is a problem of the conventional configuration.

The present invention solves the above-mentioned conventional problems, and suppresses heat transfer from the vaporization section into the fuel oil and prevents condensation of vaporized gas once, and reduces tar generation in the vaporization section. To do.

Means for Solving the Problems Means of the present invention is a vaporization section including a heating element and a liquid fuel suction body, and a burner section provided on the downstream side of the vaporization section,
A blower means for sending vaporized gas carrying air to the vaporization section, a discharge pipe having a pump provided between the vaporization section and a fuel tank, and a return pipe, and a part of the vaporization section for liquid fuel circulation. It is provided in the flow, and a flow path dividing portion is provided between the vaporized gas carrying air flow path and the liquid fuel circulation flow path.

Operation By the above means, the fuel oil in which a part of the wicking body is immersed is made to flow, the oil surface is prevented from becoming high temperature due to the heat transfer from the heat generating element, and the air passage for vaporized gas transfer is provided. Separation from the liquid fuel circulation flow passage prevents hot fuel gas once vaporized from coming into direct contact with the cold liquid fuel circulation flow and condensing there. The former prevention of the temperature rise of the fuel oil is to prevent tarification of the fuel oil due to the air oxidation described above, and the latter prevention of condensation of the fuel vaporized gas also aims at the same prevention of tar formation.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

The lower portion of the wicking body 9 provided around the outer periphery of the heating element 8 is
It is placed in the fuel flowing through the circulation channel 10. The vaporized gas carrying air flow path 12 and the circulation flow path 10 are vertically divided by a flow path dividing portion 11 which functions as a partition plate. The fuel in the fuel tank 13 is sucked up by the pump 14 through the discharge pipe 15, passes through the lower part of the suction member 9 of the circulation flow path 10, and flows down to the fuel tank 13 by the return pipe 16. The heating element 8 is a coil-shaped resistor that generates heat when energized. The wicking member 9 is made of a heat-resistant inorganic fiber material such as alumina or silica, and sucks the above-mentioned fuel from the bottom of the circulation channel 10 to the heating element 8 by the capillary phenomenon. That is,
The heating element 8 and the suction element 9 constitute a vaporization section for vaporizing the liquid fuel. The blower 17 provided on the upstream side of the vaporizing section sends the fuel vaporized gas carrying air to the vaporizing section. Further, a part of the vaporized gas-carrying air does not pass through the vaporization section, and the pneumatic tube 18 on the outer periphery of the circulation channel 10 is provided.
Through the gap 19 at the connecting portion between the burner 20 and the vaporized gas carrying air flow path 12, and flows toward the burner 20. Burner again
20 is attached to the pneumatic tube 18 via a gap 19.

Further, the vaporization portion including the heating element 8 and the suction body 9 is fixed to the upper lid 22 of the vaporized gas transporting air flow passage 12, and by opening the pneumatic tube lid 23, it is easier to attach and detach than the device. ing.

In the above embodiment, the fuel in the fuel tank 13 is sent to the circulation passage 10 by the pump 14, and the fuel flows through the bottom portion of the circulation passage 10 having a downward gradient in the downstream direction and the return pipe 16
To return to the original fuel tank 13. In this case, the fuel flow rate is always higher than the required vaporization amount. Here, when the heating element 8 is energized, the fuel sucked up by the capillary tube is vaporized by heating from the upper part of the suction member 9. This vaporization amount has a constant relationship with the amount of electric power that has been supplied. The vaporized gas is mixed with the vaporized gas carrying air sent from the blower 17 and sent to the burner 20 for combustion. At this time, the high temperature vaporized gas is circulated by the flow channel dividing unit 11
Since it does not come into direct contact with the low-temperature fuel circulation flow that flows through 10, the structure is such that condensation into fuel does not occur.

On the other hand, the air flowing through the outer circumference of the circulation flow channel 10 flows in through the gap 19 and mixes and dilutes the vaporized gas already mixed with the air. This air is used for the upper lid 22 with which the vaporizing part can be detached.
Also, the vaporized gas is prevented from leaking out of the apparatus through the gap 19. Further, the gap 19 prevents the combustion heat from the burner 20 from being transferred to the vaporization section. Furthermore, the purpose of the heat insulating material 21 is also the same. The necessity of preventing heat transfer from the burner section will be described later.

With the above structure, since the low-temperature fuel always flows below the suction body 9, the lower portion of the suction body 9 is kept at a low temperature. The upper part of the wicking body 9 in contact with the heating element 8 has the same temperature as the conventional configuration, but since the lower part is kept at about room temperature, the fuel rising in the capillary tube of the wicking body 9 is vaporized. The high temperature range to be placed can be made very narrow. That is, it is possible to make the temperature gradient in the vertical direction of the wicking body 9 steep by giving the flow of fuel to the lower part, and by narrowing the high temperature region where oxidation and tar formation are likely to occur, the tar formation of the fuel is remarkably reduced. It suppresses. Further, the local increase in temperature of the fuel oil surface that occurs when the fuel oil in which the wicking body 2 is immersed, which is seen in the conventional configuration, does not occur. Of course, in the present invention, the returning fuel causes a slight temperature rise, but the fuel tank 13 is separated from the vaporization section,
Moreover, since the fuel tank 13 radiates heat, the fuel temperature does not rise to such a high temperature that tar is generated.

Further, in the case where the flow path dividing portion 11 is not provided, the return oil temperature rises due to the condensation of the fuel vaporized gas in contact with the fuel circulation flow, but with the configuration of the present invention, this condensation can be prevented and the temperature rise of the fuel oil can be prevented. It can be prevented.

It is as described above that the configuration of the present invention has a significant effect on the suppression of tarring, but the configuration of the present invention can further increase the wicking ability of the capillaries of the wicking body 9. it can. When sucking up the stationary fuel, only the force due to the capillarity due to the capillaries in the suction body works, but in the case of flowing fuel, the force of the fuel flow acts on the suction body 9 as a flow resistance member. ing. The force of this flow increased the wicking amount of fuel, and in the experiment, the maximum wicking amount that could be vaporized by the same wicking body was increased by about 20% due to fluidization.

This result shows that the fluidization of the fuel makes it possible to raise the fuel up to the vaporization site even if it tars and the capillaries are clogged to some extent. It can be said that it was held. Together with the action of the above-mentioned temperature gradient, it exerts a remarkable effect in improving the life characteristics of the present invention.

In the configuration of the present invention, it is desirable to provide an inclination in which the upstream portion of the liquid fuel circulation flow channel is upward with respect to the downstream portion. This is because by increasing the flow velocity of the circulation flow, by preventing the temperature of the fuel oil from increasing due to heat conduction from the heating element 8, it is possible to more effectively prevent the lowering of the suction capacity of the suction member 9. This is because the wicking ability can be increased due to the increase in the flow velocity described above.

Further, in the configuration of the present invention, it is desirable that the liquid fuel wicking member of the vaporization section is installed substantially parallel to the flow direction of the vaporized gas carrying air. This is because when the gas flow is not substantially parallel to the flow direction, especially when the gas flow is orthogonal to the flow, the vaporized gas carrying air flow is likely to be turbulent in the vaporization section, and the vaporized gas is likely to be condensed on the flow path wall or the like. This is because. The condensed fuel has a history of being vaporized at a high temperature, and thus is significantly oxidized, which becomes a factor that accelerates tar formation in the vaporization section. However, the above-mentioned turbulent flow is a problem that occurs when the air flow rate is large (when the vaporization amount is large), and when the vaporization amount is not required so much, the air amount is not required too much. The life characteristic of the vaporizing part does not matter.

Furthermore, by thermally separating the burner 20 and the vaporized gas transfer passage 12, it is possible to prevent the vaporization part and the circulation flow from being heated to a high temperature due to heat transfer by combustion, and to further enhance the tarring suppression effect of the present invention. It is a thing. Further, the upper lid 22 is not only for facilitating the attachment / detachment of the vaporizing part, but also for preventing the vaporized gas from condensing on the channel wall by cooling the vaporized gas passage by the low temperature circulating flow. Yes, good results are obtained for this purpose.

Further, it is desirable to carry a platinum group catalyst on the wicking body 9. This is because by supporting the catalyst, the tar component accumulated on the wicking body after being used for a long time can be oxidatively decomposed by the catalytic action, and the wicking body can be regenerated.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to remarkably reduce the time-dependent decrease of the vaporization amount due to the liquid fuel tarification in the vaporizer of the liquid fuel combustion apparatus mainly composed of the wicking body and the heating element.

[Brief description of drawings]

FIG. 1 is a longitudinal section of a vaporizer in one embodiment of the present invention,
2 is a sectional view of FIG. 1A-A ', and FIG. 3 is a sectional view of a conventional example. 8 ... Heating element, 9 ... Suction element, 10 ... Circulating flow path, 11 ...
Flow path dividing part, 14 …… Pump, 17 …… Blower.

Front page continuation (72) Inventor Masato Hosaka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP 55-140011 (JP, A) JP 61-285308 (JP, JP, A) Actual development Sho 56-136924 (JP, U)

Claims (2)

[Claims] 1. A vaporization section composed of a heating element and a liquid fuel suction body, a burner section provided on the downstream side of the vaporization section, and a vaporization section installed on the upstream side of the vaporization section for conveying vaporized gas to the vaporization section. Blower means for sending the working air, a discharge pipe having a pump provided between the vaporization section and the fuel tank, a liquid fuel circulation flow passage and a return pipe, and sucks fuel from the fuel tank by the pump, A liquid fuel circulation flow passage is formed in which the fuel returns to the fuel tank via the discharge pipe, the liquid fuel circulation flow passage, and a return pipe, and in the liquid fuel circulation flow passage, the upstream portion is with respect to the downstream portion. An inclined upper portion is provided, a part of the vaporization part is provided in the liquid fuel circulation flow path, and a flow path dividing part for separating the vaporized gas carrying air flow path and the liquid fuel circulation flow path is provided. Liquid fuel combustion equipment. 2. The liquid fuel combustion apparatus according to claim 1, wherein the liquid fuel suction body of the vaporization section is installed substantially parallel to the flow direction of the vaporized gas carrying air.