JPH0443165B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a liquid fuel combustion device that can be used in a wide range of applications from household kerosene stoves to industrial kilns.

(Prior Art) Combustion of liquid fuel includes combustion for the purpose of heating as in a stove, combustion for heating a heated object, and combustion as a power generating engine such as an internal combustion engine.

Conventional combustion methods include either directly vaporizing and combusting liquid fuel, or splitting it into fine mist using a spray device and then combusting it.

The former type of direct vaporization combustion is often used in general household kerosene stoves.
35713), the core type (Japanese Patent Application Laid-open Nos. 58-203307 and 60-64134), and the vaporization type (JIS 3030).

The pot type uses an evaporation plate to evaporate and burn the fuel, and the vaporization section and combustion section are integrated.
The wick type has a wick of asbestos or other material inserted into the fuel tank that absorbs the fuel and has an expanded surface area to facilitate evaporation. When ignited, the flame spreads throughout the wick and continues burning.

Further, the vaporization type is a method in which the fuel is evaporated in a vaporization chamber or a vaporization tube and then burned in a combustion section, and the vaporization section and the combustion section are separated.

On the other hand, although spray combustion is used in some household oil stoves, it is mostly used in industrial furnace boilers and the like. This combustion atomizes liquid fuel into fine oil droplets, increasing the area of contact with air and promoting evaporation and combustion reactions.

Commonly used oil burners include rotary burners, jet burners (steam atomization, air atomization, mechanical atomization), special burners (gun type high pressure atomization, low pressure atomization), and the like. Also,
There is also an example of a type of ignition device in which liquid fuel is turned into foam and ignited by an electric spark (Special Publication No. 49-
No. 42018, Japanese Unexamined Patent Publication No. 47-38368).

(Problems to be Solved by the Invention) In the pot-type combustion method, which directly vaporizes liquid fuel, after ignition, until the combustion chamber is sufficiently warmed,
It is difficult to increase combustion rapidly, and it takes a considerable amount of time for kerosene stoves and the like to become warm after ignition. In addition, with combustion methods such as the wick type, the range in which the amount of combustion can be varied is narrow, and depending on the outside air conditions and the size of the room, it is not always possible to provide comfortable warmth.

Furthermore, it is a well-known fact that there is a belief that kerosene stoves emit a smell, as the odor produced when ignited or extinguished is unbearable.

In particular, odors during digestion must be eliminated quickly due to safety considerations (for example, JIS stipulates that if the equipment is shaken by an earthquake or accidentally knocked over, it will disappear within 10 seconds). As a reaction to this, the fact is that the smell of digestion tends to become even stronger.

This means that the flame disappears faster after the extinguishing operation, for example in the case of a kerosene stove.
Even after extinguishing, fuel vapor still evaporates from the wick or pot, and as it passes into the still-hot combustion cylinder,
It oxidizes to aldehydes and the like that have a pungent odor, resulting in a strong odor that causes discomfort and other problems.

On the other hand, although there are many types of combustors for the spray combustion method, in all of them, when oil droplets are sprayed together with air, the oil droplets have a wide particle size distribution, and each particle interacts with each other. Move in different directions and at different speeds.

Therefore, the spray combustion lacks uniformity, and the oil droplets reach the front of the flame and are surrounded by the diffusion flame without undergoing sufficient evaporation and mixing processes, which tends to result in a non-uniform flame. Therefore, there are problems such as local overheating of the object to be heated.

Additionally, equipment for spraying oil is required.
The disadvantage was that running costs such as power costs were high.

The examples disclosed in Japanese Patent Publication No. 49-42018 and Japanese Patent Application Laid-Open No. 47-38368 function as ignition devices, and cannot be used as means for stably performing continuous combustion.

(Means for Solving the Problems) The present invention expands the range of variable fuel amount of liquid fuel,
To provide a combustor that converts liquid combustion into foam and continuously burns it, in order to prevent odor during ignition and extinguishment, and to improve uneven flame spray.

Here, the foam refers to an aggregate of bubbles surrounding a gas such as air or oxygen with a thin film of liquid fuel. Specifically, it is obtained by blowing gas such as air into liquid fuel such as kerosene, and to promote foaming,
It also includes those obtained by adding a blowing agent.

The noteworthy characteristics of this foam combustion are:
It is possible to increase the contact area between fuel and air in a manner different from conventional methods, thereby promoting evaporation and combustion reactions.

The present invention is a combustion device that stably burns such foamed fuel and expands the variable range of combustion amount.

FIG. 1 is a sectional view showing the structure of the present invention, and FIG. 2 is a plan view.

In the figure, 1 is a combustor, 2 is a bubble collector, 3 is an orifice, 4 is a foam generator, and 5 is a porous element. A fuel supply pipe 6 for supplying liquid fuel from the outside is connected to the foam generator 4.

On the other hand, a porous element 5 is installed inside the foam generator 4, and a foaming air supply pipe 7 is connected thereto so that gas such as air can be supplied from the outside. 8 is a secondary air supply pipe for combustion, and 9 is a secondary air supply hole.

The combustor 1 is a cylindrical body with an orifice 3 at the bottom and a cylindrical or rectangular side part,
A large number of secondary air supply holes 9 are provided.

Therefore, the foamed fuel reaches the orifice 3 from the bubble collection tube 2, is supplied to the combustor 1 through the opening 10, and is supplied through the air contained in the bubbles of the foam and the secondary air supply hole 9. It is easily combusted by the surrounding air, forming a flame upward.

FIG. 3 shows the combustion state of the liquid fuel according to the present invention.

h is the rising height of the foam. 11 is fuel, 12
13 indicates bubbling air, and 13 indicates secondary combustion air.

The porous element 5 is made of sintered metal, porous ceramics, or the like. The liquid fuel supplied to the foam generator 4 is easily foamed by the fine airflow ejected from the porous element 5.

The combustor 1 is formed integrally with an orifice 3 interposed in the upper part of the bubble collector cylinder 2, but the combustor 1 may be divided into parts.

Generally, the foaming ratio (volume of foam/volume of liquid fuel) of foam obtained only with liquid fuel such as kerosene is approximately 5 to 50 times. On the other hand, in order to achieve complete combustion using only the air (oxygen) in the foam, the foaming ratio needs to be approximately 9000 times (1900 times in the case of oxygen).

Therefore, combustion air 13 is required in addition to foaming air 12 for foam combustion. This combustion air 1
3 is supplied from a secondary air supply pipe 8 and discharged from a hole 9 attached to the side of the combustor 1 to completely burn the fuel. 14 indicates the combustion flame generated.

Foam 2' in the bubble collection tube 2 connected to the combustor 1 is
When exposed to radiant heat from the combustion flame 14, defoaming is promoted, the particle size of the foam and the thickness of the thin film become non-uniform, causing pulsating combustion.

The present invention provides an orifice (throttle mechanism) 3 between the combustor 1 and the bubble collecting tube 2 to suppress direct radiation from the flame 14 generated in the combustor 1 into the bubble collecting tube 2. Therefore, defoaming of the foam 2' is suppressed to a minimum, and stable combustion continues.

Further, it is desirable that the orifice 3 has a cup-like shape that expands conically in the direction of the combustor 1. By doing so, the area that acts on the evaporation of foam can be made variable, and the device can function as an evaporation amount variable device. Reference numeral 15 indicates an evaporation amount variable function section.

By changing the flow rate of the foaming air 12 to control the rising height h of the foam, and by changing the evaporation area of the foam 2', the amount of combustion can be freely controlled. This greatly improved the combustion variable control range.

FIG. 4 shows another embodiment of the present invention, in which the structure of the evaporation amount variable function section 15 installed in the combustor 1 and having a conical spread is set at stages 15a, 15b, 15.
It has a step-like structure as shown in c.

Therefore, this embodiment is suitable for controlling combustion by dividing the combustion amount into three stages. In addition,
The number of stages is not limited to this. Steps 15a, 15
b and 15c, each has a vertically extending portion whose cross-sectional area does not change, and even if the foam rising height h changes somewhat due to fluctuations in the foaming air 12 or other factors, the foam evaporation area will not change. For each change within the same vertical section, the combustion amount is approximately constant. Therefore, it is suitable for controlling the combustion load in several stages.

Note that the orifice 3 may have a structure in which the orifice 3 is simply constricted by one plate, but in that case, the influence of the radiant heat of the combustion flame 14 is large. Although it may be better to raise the temperature of the orifice 3 to a certain extent, this should be set appropriately depending on the properties of the fuel, etc.

Generally, radiant heat transfer into the bubble collecting tube 2 (time radiation)
Although the influence is small, it promotes defoaming. Therefore, in the first embodiment of the present invention, the orifice structure is shaped like a cup to form a constricted part, and the outside of the maximum constriction part is cooled with air etc. Indirect radiation heat transfer into the bubble tube 2 is suppressed.

(Effects of the Invention) As explained in detail above, the present invention is a combustor that burns liquid fuel by turning it into foam, which is easier to ignite without using a wick, compared to the conventional direct vaporization method. In addition to the unique advantages of foam combustion, such as being able to ignite and easily controlling the amount of combustion immediately after ignition, it also stabilizes combustion and expands the variable range of combustion amount, greatly improving the range of applications. It is something.

Furthermore, it has the effect of significantly reducing the generation of odor during ignition and extinguishing.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing the structure of the present invention, FIG. 2 is a plan view, FIG. 3 is an explanatory diagram illustrating the combustion state according to the present invention, and FIG. 4 is an explanatory diagram showing another embodiment of the present invention. It is a diagram. 1: Combustor, 2: Foam collector, 3: Orifice,
4: Foam generator, 5: Porous element, 9: Secondary air supply hole, 10: Open hole, 15: Evaporation amount variable function section.

Claims (1)

[Scope of Claims] 1. A liquid fuel combustion device for turning liquid fuel into foam and combusting it, characterized in that an orifice is provided between a combustor and a bubble collecting tube that sends fuel to the combustor. 2. The combustion device according to claim 1, wherein the orifice has a cup-like shape that expands conically in the direction of the combustor, and is formed to have a variable evaporation amount function. 3. Claim 1 or 2, in which the shape of the orifice is expanded in stages in the direction of the combustor.
Combustion device as described in section. 4. The combustion device according to claim 1, 2, or 3, wherein the orifice shape is a cup-like shape or a stepped shape, and has a constricted part so that it can be cooled from the outside.