JPH02259311A - Method and device for igniting liquid fuel - Google Patents

Abstract

PURPOSE:To promote evaporation of fuel and promote a combustion reaction in a home-use petroleum stove or the like by a method wherein gas is passed through porous plates and introduced into liquid fuel to make bubble fuel and then combustion air is separately supplied. CONSTITUTION:Air is sent from a gas supplying pipe 6 and fuel is supplied from a fuel tank 1 to a combustion unit 10 through a supply pipe 8. In this way, the air is passed through an air feed device 2 composed of porous plates and this air is supplied into the fuel to make bubbled fuel so as to be ignited by an ignition heater 11. In turn, combustion air is supplied into the combustion device 10 through a supply pipe 7 and supply holes 21. A mixing of fuel and combustion air is promoted by a flame holding device 9 so as to provide a complete combustion. With such a configuration, it is possible to promote an evaporation of fuel and combustion reaction.

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

The former type of direct vaporization combustion is widely used in general household petroleum gas stoves, including the pot type (Japanese Utility Model Publication No. 58-35713) and the wick type (Japanese Unexamined Patent Publications No. 58-203307, 1983).
-64134 each publication 1 or vaporization type (JIS303
0).

The pot type uses an evaporating dish to evaporate and burn the fuel, and the vaporizing part and combustion part are integrated.

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 kerosene 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 are rotary burners, jet burners (steam atomization, air atomization, mechanical atomization), special burners (gun type high pressure atomization, low pressure atomization), and the like. There are also examples of a kind of ignition device in which liquid fuel is turned into foam and ignited by an electric spark (Japanese Patent Publication No. 49-42018, Japanese Patent Application Laid-Open No. 47-38368).
Publication No.).

(Problems to be Solved by the Invention) In combustion methods such as the pot type in which liquid fuel is directly vaporized, it is difficult to rapidly increase combustion until the combustion chamber is sufficiently warmed after ignition. So, after igniting it, it will take quite a while until it gets warm! do. In addition, combustion methods such as the wick type have a narrow range in which the amount of combustion can be varied, making it impossible to always provide comfortable warmth depending on the outside air conditions and the size of the room.

Furthermore, it is a well-known fact that there is a perception that kerosene stoves are smelly, and that the smells produced when igniting or extinguishing a fire are unbearable.

In particular, the odor when extinguishing a fire must be extinguished quickly for safety reasons (for example, JIS stipulates that odors must be extinguished within 10 seconds due to vibrations such as an earthquake or when equipment is accidentally knocked over. As a reaction to this, the fact is that the smell when extinguishing a fire tends to become stronger.

This means that the flame disappears quickly after the extinguishing operation. For example, in the case of a kerosene stove, fuel vapor evaporates from the wick or pot even after the extinguishing operation, and when it passes through the still hot combustion cylinder. , it is oxidized to aldehydes and the like that have a pungent odor, resulting in a strong odor and causing discomfort.

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

Therefore, the spray combustion lacks uniformity, and the oil droplets reach the front of the fire without being sufficiently evaporated and mixed, and are surrounded by a diffusion flame, which tends to result in an unconfined flame.

Therefore, there are problems such as local overheating of the object to be heated.

In addition, equipment for spraying oil is required, which has the disadvantage of increasing running costs such as power costs.

The aforementioned Japanese Patent Publication No. 49-42018 and Japanese Unexamined Patent Publication No. 47-3
The example presented in Publication No. 8368 functions as an ignition device, and cannot be used as a means to stably perform continuous combustion.

(Means for Solving the Problems) The present invention provides a new combustion method and device to improve the above-mentioned drawbacks.

The present invention provides for freely adjusting the amount of combustion immediately after ignition of a kerosene stove,
In order to prevent odor during ignition and extinguishing, and to improve the unrestrained flame of spray, this method provides a method for converting liquid fuel into foam and immediately and continuously burning it in a combustor.It is especially effective when applied to kerosene stoves. It is remarkable.

Here, the term "bubbles" is a general term for dispersed bubbles, in which a large number of bubbles made of gas such as air or oxygen are suspended in a liquid, and foam, which is an aggregate of bubbles separated by a thin liquid film.

A notable characteristic of the method of burning liquid fuel as foam or dispersed bubbles is that it can increase the contact area between the fuel and air in a different manner from conventional methods, and it also increases the evaporation diffusion coefficient and This has the effect of lowering the partial pressure of fuel vapor at the gas-liquid interface, promoting evaporation and combustion reactions.

Hereinafter, the present invention will be explained based on the drawings.

The figure is a longitudinal sectional view showing an embodiment of the present invention. Reference numeral 2 denotes an air supply device having a function of foaming fuel, which is a feature of the present invention. 22 indicates an evaporating dish.

Fuel is supplied from the fuel tank 1 through the pump 3 and supply pipe 8 into the combustor lO. At the lower part of the combustor 10, an evaporation plate 22 and an air supply device for generating bubbles are formed and arranged in series. A wind box 4 for supplying combustion air is installed on the outside of the combustor IO located above it. Regarding the positional relationship between the air supply device 2 and the evaporation dish 22, the upper surface of the air supply device 2 and the lower end of the evaporation dish 22 may be on the same level, or may have a stepped configuration.

The liquid fuel is supplied to the evaporation tray 22 at the upper part of the air supply device 2, and by blowing gas into the lower part from the gas supply pipe 6, the fuel (kerosene, light oil, etc.) is foamed, and the foam is heated by the ignition heater 11. It ignites and burns. In addition, air necessary for complete combustion is separately supplied from a supply pipe 7 through a wind box 4 for continuous combustion. 5 indicates flame.

By increasing the amount of fuel supplied from the fuel supply pipe 8 and the amount of air supplied from the gas supply pipe 6 to increase the amount of bubble generation, and by increasing the amount of air from the combustion air pipe 7, the amount of combustion can be easily increased. can be done. Furthermore, the results showed that the flame becomes longer as the amount of gas (air) from the gas supply pipe 6 increases while keeping the combustion supply amount constant.

These results are due to the effects of promoting foaming of the fuel, increasing the evaporation area of the liquid fuel, increasing the diffusion coefficient from liquid to gas, and lowering the fuel vapor partial pressure at the gas-liquid interface. This is thought to improve the amount of evaporation and increase the amount of combustion. Therefore, the combustor 10 can be easily made compact.

In addition, since the present invention ignites the liquid fuel in the form of foam, it can be easily ignited by simply bringing the ignition source into direct contact with the foam.

In addition, when extinguishing a fire, the fuel supply to the combustor 10 is stopped and the fuel remaining in the combustor is foamed and burned, so the time from stopping the fuel supply to completely extinguishing the fire is short and there is no smell. .

In this way, by once burning the fuel as bubbles,
By adjusting the amount of air blown from the gas supply pipe 6 and the amount of fuel supplied, and by changing the amount of air supplied from the fuel air supply pipe 7, combustion characteristics such as the combustion amount and flame shape can be freely controlled. be able to. It also enables immediate heating and odor-free combustion in kerosene stoves, which was not possible with conventional technology.

Next, the reason why air must be separately supplied from the combustion air pipe 7 in the present invention will be explained.

Foam expansion ratio (
The apparent volume of the mixed state of liquid and gas/liquid fuel volume is
It is usually about 5 to 50 times. However, the required magnification of air for complete combustion is about 9,000 times, and the amount of air in the bubbles is nowhere near that.

However, for combustion, some of the air supplied from the gas supply pipe 6 does not remain in the bubbles and can be used directly as combustion air, so the amount of air supplied from the combustion air pipe 7 is A preferred range is approximately 60-150% of the air content.

Here, the lower limit of 60% means that the liquid fuel on the air supply device 2 exists as bubbles for only a moment due to radiant heat from flames, etc., and most of the time is stable combustion due to dispersed bubbles and direct evaporation from the liquid fuel. This indicates the maximum flow rate that is limited by the pressure loss of the air supply device 2, etc., which does not require the amount of air from the gas supply pipe 6 to be an appropriate amount for stable foam generation.

In addition, the upper limit of 150% is the gas supply pipe 6 when stable foam generation is required during the transition period from ignition to stable combustion.
This is the flow rate that achieves a proper combustion state when the amount of air from the engine is secured.

It is also possible to further promote the combustion reaction by adding a polymer or a surfactant to the liquid fuel to increase the expansion ratio.

On the other hand, when using this bubble combustion for burner combustion to heat the object to be heated, foams generated only with other liquid fuels other than light oil may not have uniformity in bubble diameter or stable foaming properties. There is a slight problem with the conversion. Therefore, as a foaming agent, polymers, surfactants, silicone resins, or mixtures thereof, or light oil with good foaming properties are mixed with liquid fuel.
By increasing the surface viscosity and lowering the surface tension to improve foaming properties, stable foam generation is possible, and the combustion of the foam injected from the burr maintains a stable and uniform flame, which helps to maintain the flame of the heated material. It is possible to exhibit the effect of preventing local heating.

(Example) Next, the apparatus of the present invention will be explained in detail using an example shown in FIG.

An air supply device 2 and a combustion supply port 11 are provided in the lower part of the combustor 10 to generate foam and dispersed bubbles of liquid fuel.
A gas supply pipe 6 is connected to the combustor to form a bubble generation region a, and a large number of combustion air supply holes 12 are provided in the upper side of the combustor to form a combustion region in which the liquid fuel is combusted. The main part of the air supply device 2 is composed of a porous plate or a porous element, and has a foaming function. The bottom is pot-shaped.

Approximately 0.84 ml of combustion air is supplied from the combustion air supply pipe 7 to the combustor lO through the wind box 4 and the air supply hole 12 from the zero-order gas supply pipe 6! /1n of air is passed from the combustion tank 1 through the supply pipe 8 to a temperature of 2.
℃ fuel (kerosene) 0.5m! When /H was supplied to the combustor lO, fuel bubbles were generated on the air supply device (sintered metal perforated plate) 2, rose to the ignition heater 11, and were ignited by the red-hot nichrome wire.

The combustion state at this time was complete combustion in which the flame stabilizer 9 promoted the mixing of the fuel and combustion air, and a pale flame extended above the flame stabilizer. At this time, it took only 20 seconds from ignition until a flame was generated above the flame holder.

Further, as the amount of air from the combustion air supply pipe 7 was reduced, the length of the flame gradually became longer, and the color of the flame also began to take on a camphor color.

Next, from this combustion state, the amount of air supplied from the gas supply pipe 6 was gradually increased to promote foaming of the fuel, and the flame length became even longer and its color changed to bluish-white. The amount could no longer be followed and the flame length became shorter. This promotes foaming of liquid fuel, increases the amount of fuel evaporation, and shortens the residence time of the liquid in the combustor.
This is thought to be due to the amount of combustion increasing over time.

Next, increase the amount of fuel supplied to 1. oj! /H, the amount of combustion air is increased to 1604! /sin, the flame immediately became a large blue-white color above the flame stabilizer and continued stable combustion.

Thereafter, when the fuel supply was stopped, the combustion of the remaining fuel in the combustor immediately ended with foaming combustion, and the fire was completely extinguished by stopping the amount of air supplied from the gas supply pipe 6. At this time, no odor was generated.

In addition, in this experiment, a porous plate with holes of a certain diameter was used, but bubbles can also be generated using a thin tube, a cloth particle layer, or a combination of these methods. This does not limit the material or shape of the quality element.

(Effects of the Invention) The present invention is a method in which liquid fuel is supplied to the outside of a porous element, and the liquid fuel is immediately combusted in the form of bubbles by the gas supplied into the porous element, so the evaporation surface area of the fuel is significantly increased. , promoting evaporation and combustion reactions.

Therefore, the combustor can be made more compact, and there is no odor or soot generated when igniting or extinguishing.Furthermore, it is easy to vary the amount of combustion, even immediately after ignition, and it is easy to control the flame shape. It's easy to do.

[Brief explanation of drawings]

The figure is a longitudinal sectional view showing an example of a combustion device for carrying out the present invention. l: fuel tank 2: air supply device (perforated plate) 3: pump 4 + wind box 5: flame 6: gas supply pipe 7: combustion air supply pipe 8: fuel supply pipe 9: flame holder lO: combustor 11; Ignition heater 12: Air supply port 22: Evaporating plate Agent Patent attorney Tatsuo Chanoki

Claims (1)

[Scope of Claims] 1. Gas is introduced into liquid fuel by an air supply method through a thin tube, perforated plate, cloth, particle layer, etc., and the liquid fuel is immediately combusted as foam or dispersed bubbles, resulting in stable combustion. A method of burning liquid fuel, which is characterized by separately supplying the combustion air required to continue combustion and burning it in a combustor. 2. In a device that immediately burns liquid fuel as foam or air bubbles, a foam-generating air supply device and an evaporation tray are installed in series at the bottom of the combustor, and combustion air holes are provided in the side wall that extends above the device. A liquid fuel combustion device characterized by: 3. The combustion device according to claim 2, wherein a cylindrical skeleton is attached to the lower surface of a baffle plate having openings, and a flame stabilizer is placed directly above the central axis of the bubble-generating air supply device.