JPH05322129A - Vaporizer and heating method therefor - Google Patents

Abstract

PURPOSE:To reduce odor of fuel by reducing power consumption required for electric resistance heating to be used for heating a vaporizer and shortening a time up to ignition by accelerating a temperature rising speed in the vaporizer to be used for an apparatus for burning liquid fuel such as a petroleum fan heater. CONSTITUTION:In a vaporizer 1 receiving the liquid fuel and air or the liquid fuel, and heating them to vaporize the fuel, there is provided a thin filmlike electric resistance heat generator 10 on a wall such as an outer wall 6 thereof or on a bottom. The generator 10 is composed in a structure in which an insulating layer 7, a heat generating layer 8 and an insulating layer 9 are, for example, laminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a liquid fuel combustion device,
For example, it relates to a vaporizer used in a kerosene combustion device, and more particularly to a vaporizer used in an oil stove such as an oil fan heater and a heating method thereof.

[0002]

2. Description of the Related Art Conventionally, there are various types of liquid fuel combustion devices, but household ones are often used so-called petroleum stoves that burn kerosene because they are easy to handle and highly safe. It is an oil fan heater that has been improved to make it more safe and it is now widely used. In this petroleum fan heater, kerosene is normally vaporized in a vaporizer, mixed with air, sent to a combustion chamber, and burned in the combustion chamber.

The types of vaporizers used in such oil fan heaters include (1) hydraulic feed and atomization,
There are various methods such as (2) mist blowing and (3) Bunsen,
In any method, in order to vaporize kerosene, it is necessary to heat it to a boiling point of 160 to 240 ° C. or higher, so a sheath heater is usually provided in the vaporizer for electric heating. This will be described with reference to the drawings. FIG. 5 is a front view of a conventional vaporizer, FIG. 6 is a longitudinal sectional view thereof, and FIG. 7 is a bottom view thereof. The vaporizer 20 shown in FIG. 5 has an outer diameter of 50 m, for example.
An annular sheathed heater 23 is provided around the upper end of a main body 21 made of a cylindrical aluminum die-casting container having a height of about 40 mm and a height of about 40 mm. A part of the sheathed heater 23 is provided with a lead-out portion 24. Has been. The lead-out portion 24 is provided with a lead wire 25 for supplying an electric current to the sheath heater 23. The electric current from the lead wire 25 causes the sheath heater 23 to generate heat, which heats the main body 21 from the outside. To a high temperature. A premixing supply port 26 is provided on the side opposite to the outlet portion 24 of the main body 21, from which kerosene and air are sent at a predetermined ratio, are blown into the vaporization chamber 22, are heated in the vaporization chamber 22, and are heated. Is converted to steam and sent to the combustion chamber (not shown) from above. 27 is the bottom.

[0004]

However, in such a heating method, the heating element of the nichrome wire of the sheathed heater is heated by electric resistance to heat the powder of the insulating material MgO and the metal of the sheath, and Since the double indirect heating method of heating the carburetor body mainly by conduction heat transfer is adopted, a large amount of heat is required to heat only the sheath heater,
There is a problem that the temperature rising time is long and the power consumption is large. Further, since the thermal resistance between the substances is large, the nichrome wire is heated to a temperature higher than the required temperature, so that the nichrome wire is easily broken or deteriorated, and there is a problem in durability.

On the other hand, in order for the kerosene to be atomized in the vaporizer, a certain residence time is required depending on the size of the kerosene particles ejected from the nozzle, but in practice, the vaporizer temperature is about 250 ° C. Because it is ignited when it reaches
It is unavoidable that kerosene vapor goes out before ignition and gives off a smell. As a measure against this, there are products that have a function that allows the carburetor to be energized at all times even when it is not burning, so that it can be ignited immediately after starting. It is not always desirable.

In addition to the above-mentioned problems, since most of the demand destinations for oil fan heaters are ordinary households, the total power capacity of ordinary households is as small as 2-3 KW, and when the oil fan heater consumes a large amount of power. However, it is inconvenient that it occupies a considerable part of the total power capacity and restricts the use of other household electric appliances, so that the power consumption should be as small as possible. Moreover, the oil fan heater is safe and reliable,
And it is required to be inexpensive.

It is an object of the present invention to provide a vaporizer for liquid fuel which consumes less electric power and is safe and highly reliable.

[0008]

Means for Solving the Problems The present inventor has made various studies on the structure of a carburetor in order to solve the above-mentioned problems, and the properties of the carburetor, that is, the physical properties of the shape and the material are important. Especially in the case of rapid heating, when the electric power is constant, the density, volume and specific heat of the vaporizer including the heating source are reduced,
It has been found necessary to increase the thermal diffusivity and power density. The present invention has been reached as a result of studying means for increasing the thermal diffusivity and the power density in consideration of the above.

That is, the present invention has achieved the above object by the following means. (1) In a vaporizer that introduces liquid fuel and air or liquid fuel and heats them to vaporize the liquid fuel, a thin-film electric resistance heating element is provided on the bottom or the wall of the vaporizer. Characterizing vaporizer. (2) A heating method of a vaporizer, characterized in that the vaporizer is heated by electric resistance heating by energizing a thin film electric resistance heating element provided in the vaporizer according to the item (1).

The shape of the main body of the vaporizer of the present invention may be the same as the shape of the main body of the conventional vaporizer, and may be, for example, the shape shown in FIG. As the material forming the vaporizer body, for example, aluminum or its alloy, copper alloy,
A magnesium alloy, a nickel alloy, or the like can be used. Among them, aluminum or its alloy is preferable, and the vaporizer main body can be manufactured by using the aluminum or its alloy.

The position of the thin film resistance heating element provided on the wall of the vaporizer may be on the outer wall, the inner wall, or the bottom of the vaporizer, and may be provided at two or more places, but on the inner wall. In this case, since it is directly or indirectly affected by liquid fuel or the like, it is better to have it on the outer wall that does not have the influence. As the installation position on the outer wall, the heat generated from the thin-film electric resistance heating element is transferred to the inside of the vaporization chamber through the wall of the vaporizer, so it is preferable that it is closer to the upper end of the outer wall, but in the case of wide installation Does not really matter.

As the thin-film electric resistance heating element, those already known can be used as they are. The thickness is preferably a thin film with a thickness of 5 mm or less. To form the heating element on the wall or bottom of the vaporizer,
It can be manufactured by thermal spraying, coating, print printing, or the like. As the concrete manufacturing means, the already known means can be adopted. Regarding the thermal spray heating element, a ceramic heating element (JP-A-59-94394), a heat fixing roll (JP-A-59-154478), and a method for forming a surface heating film using a natural sand iron raw material (Japanese Patent Publication No. 2). -5
6425), and these technical means may be used.

At this time, since the carburetor main body is made of a conductive metal such as aluminum, the thin-film electric resistance heating element is pre-insulated on the carburetor wall or the like because of the necessity of insulation. A layer is formed in advance, and a heat generating layer made of a thin-layer electric resistor is provided on the layer. As the electric resistor, a known one such as nickel-chromium can be used. In addition, the thin-film electric resistance heating element formed in this manner is oxidized by oxygen in the air because the temperature rises, so that it is protected or the heating element is placed on the outer wall of the vaporizer. In some cases, since it is in contact with the outside air, the generated heat is dissipated to the outside. Therefore, in order to prevent the heat radiation, it is preferable to provide a protective layer on the heating element. As the protective layer, a refractory layer such as aluminum oxide powder or a resin layer can be provided, but it is preferable to provide a heat resistant resin layer from the viewpoint of high denseness.

For example, an alumina insulating layer, a nickel-chromium heat generating layer, and an alumina insulating layer are sequentially provided on the outer surface of an aluminum vaporizer by plasma spraying to have a thickness of several mm.
Hereinafter, it is preferable to form a thin film heating element having a thickness of preferably 0.2 to 3 mm. The thickness may be thinner. The vaporizer of the present invention will be specifically described with reference to the drawings. FIGS. 1 and 2 show an example of the vaporizer of the present invention, and FIG. 1 is a partially longitudinal side view thereof. Is a bottom view. The vaporizer 1 is an aluminum cylindrical body having a bottom portion 4, a hollow cylindrical portion 2 is provided with a flange 3 at an upper end thereof, and a portion of the cylindrical portion 2 is provided with a premixing supply port 5, from which a liquid is introduced. Fuel and air are supplied. An insulating layer 7 made of, for example, alumina is formed on the outer wall 6 of the cylindrical portion 2.
And a heat generating layer 8 made of, for example, a nickel-chromium thin film is formed on the layer by thermal spraying. The heating layer 8
As shown in FIG. 1, the strips are spaced apart from each other, and the strips are connected to each other at their ends. Lead wires 13 are respectively connected to the ends 11 and 12 of the upper heat generating layer and the lower heat generating layer so that a current can flow through the heat generating layer. Then, an insulating layer 9 made of alumina, for example, is provided on the heating layer 8 to form a thin-film electric resistance heating element 10. In addition, 14 is a seat.

FIG. 3 is an enlarged vertical sectional view for explaining the structure of the thin-film electric resistance heating element 10 used in the present invention, in which a part of the cylindrical portion 2 (corresponding to the side wall) of the vaporizer 1 is vertically cut. This is an enlarged view of the portion, and the structure of the heating element is clear from this figure.

[0016]

The thin-film heating element used in the present invention, which is thin and has a thickness of several mm or less, has a substantially small time constant. Therefore, the time constant of the carburetor depends on the characteristics of the carburetor in close contact with it. It is determined. Basically, the smaller the density, volume and specific heat, the smaller the time constant.

Further, in order to make the temperature of the entire vaporizer uniform, it is preferable to provide the thin film heating element as much as possible. However, considering workability, it was found that even if only the outer surface of the carburetor was processed, it was rapidly heated by conduction heat transfer. In addition, since the adhesion is good and each material is thin, the heat transfer resistance such as contact is small, and the temperature of the heating element may be increased by several tens of degrees above the predetermined temperature, which makes it difficult for the material to deteriorate. Brings advantages. In forming the thin-film heating element, similar results can be obtained not only by thermal spraying but also by processing means such as coating, so that the manufacturing cost can be further reduced.

Although the present invention has been described with reference to the vaporizer of the oil fan heater, its principle is common to vaporizing other liquid fuels, and therefore, in other liquid fuel combustion devices. It can also be applied to a vaporizer.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. However, the present invention is not limited to this embodiment. Example 1 The outer surface of an aluminum vaporizer having a cylindrical portion with an outer diameter of 50 mm and a height of 31 mm having the same shape as that of the vaporizer shown in FIG. 3mm alumina-titania layer, 0.1mm thick, 3mm wide, 50mm long mixed layer of nickel-chromium + titania with a mixing ratio of 1: 1 as a heat generating layer, and after applying heat resistant resin as a heat insulating layer (thickness About 0.1 mm), a silver paste and a lead wire were fixed to both ends of the nickel-chromium layer to form a thin-film resistance heating element as an electrode.

Electric power of 100 V, 200 W, 350 W, and 500 W are applied to the thin-film resistance heating element,
The heating rate of the vaporizer was measured to examine the heating characteristics. At that time, in order to measure the temperature distribution of the vaporizer, K-type thermocouples were provided at the bottom and the premix feed port. 2 in FIG. 2 indicate the positions where the thermocouples are provided. At that time, for comparison, a conventional vaporizer having a structure in which a nickel-chromium sheath wire was provided on the outer circumference of the vaporizer of the same size was also measured.

The results of these measurements are shown in FIG. According to FIG. 4, a conventional vaporizer has a power of 500 W and a temperature of 250 ° C.
It took about 2 minutes and 20 seconds to reach the level,
In the vaporizer of the present invention, it takes about 1 minute 10 seconds,
It was shortened to the extent. The temperature in the figure is the temperature at the bottom of the vaporizer.

[0022]

In the vaporizer of the present invention, by using the thin film heating element, the rate of temperature rise is improved about twice as compared with the conventional type. Therefore, thermal efficiency is good and power consumption can be reduced. Since the temperature rising rate is high, the ignition can be performed quickly, so that the start is fast and the odor of the liquid fuel is less likely to occur during ignition.
Further, since the thin film heating element is used, the structure of the vaporizer becomes compact. Further, the deterioration and disconnection of the heating element are small.

[Brief description of drawings]

FIG. 1 is a partially longitudinal side view of a vaporizer which is an example of the present invention.

FIG. 2 shows a bottom view of a vaporizer which is an example of the present invention.

FIG. 3 is a vertical cross-sectional view of a part of a cylindrical portion of a vaporizer which is an example of the present invention.

FIG. 4 is a graph showing a temperature rising rate of the vaporizer in the example.

FIG. 5 shows a front view of a conventional vaporizer.

FIG. 6 shows a vertical cross section of a conventional vaporizer.

FIG. 7 shows a bottom view of a conventional vaporizer.

[Explanation of symbols]

 1 Vaporizer 2 Cylindrical part 3 Flange 4 Bottom part 5 Premixing supply port 6 Outer wall 7 Insulating layer 8 Heating layer 9 Insulating layer 10 Thin film electric resistance heating element 11 End part 12 End part 13 Lead wire 14 Seat

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Bessho 11-11 Haneda Asahi-cho, Ota-ku, Tokyo EBARA CORPORATION (72) Inventor Shuichi Ueno 11-1 Haneda-Asahi-cho, Ota-ku, Tokyo Inside the EBARA CORPORATION (72) Inventor Yoshikazu Murata 11-1 Haneda-Asahicho, Ota-ku, Tokyo Inside the EBARA CORPORATION

Claims (2)

[Claims] 1. A vaporizer for introducing liquid fuel and air or liquid fuel and heating them to vaporize the liquid fuel, wherein a thin-film electric resistance heating element is provided on the bottom or on the wall of the vaporizer. A vaporizer characterized in that. 2. A heating method for a vaporizer, characterized in that the vaporizer is heated by electric resistance heating by energizing a thin-film electric resistance heating element provided in the vaporizer according to claim 1.