JPH04251116A - Ignition device for mixed fuel of oil and water - Google Patents

Abstract

PURPOSE:To enable mixed fuel to be stably and continuously ignited even if a mixing ratio of water in respect to oil is increased by a method wherein an outside part of an inner shell is covered by an outer shell through a thermal insulating layer material layer, a plazma discharge is carried out between a pair of electrodes disposed within an inner shell and the outer shell is heated at a high temperature. CONSTITUTION:An ignition device is composed of an inner shell 12 made of ceramic formed into a hollow sphere and a metallic outer shell 16 enclosing an outside part of the inner shell through a thermal insulation material layer 14. A pair of electrodes 20 and 22 adjacent to an internal spacing 18 of the inner shell 12 passing through them are disposed at both upper and lower ends of the inner shell 12 and the outer shell 16. An AC power supply 38 for generating a plasma discharge between them is connected to both electrodes 20 and 22. Electrical discharge is generated between the upper electrode 22 and particles 34 of tungusten with which the inner shell 12 is filled and at the same time air is supplied from a supplying passage 30 to the inner spacing 18. With such an arrangement, the outer shell 16 is heated up to a high temperature, and mixed fuel of oil and water injected from a pressure injection nozzle is well gasified.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for a mixed fuel of oil and water.

0002

[Prior Art] It has been known that mixing oil with water and burning it can reduce the amount of black smoke emitted. For example, in light oil boilers, light oil is mixed with about 8% water. Mixed fuels can be used. At this time, a large amount of combustion air is forcibly fed into the combustion chamber of the light oil boiler using a blower, etc., along with a mixed fuel of oil and water that is atomized by being injected from a pressure spray nozzle. Then, use a grilled ball as a spark to ignite it.

0003

[Problem to be solved by the invention] By the way, light oil has two
Approximately 0% water can be mixed, and the higher the water content, the lower the amount of black smoke emitted. However, in conventional light oil burners that use grilled balls as the source, the water content is 8.
If the amount is increased beyond %, the temperature of the grilled balls will drop and the combustion efficiency will drop, eventually making continuous combustion impossible. For this reason, when 8% or more of water is mixed, an auxiliary burner for heating the grilled balls is required separately, which poses a problem in that the ignition device becomes larger. Furthermore, even if such an auxiliary burner is provided, there is a limit to the mixing ratio of water that can maintain continuous combustion.

[0004] Furthermore, when a large amount of combustion air is forcibly fed in to use a mixed fuel made by mixing light oil and water, there is also the problem that the amount of NOx emissions increases. Ta.

[0005] The present invention was made in view of the above circumstances, and its purpose is to increase the mixing ratio of water as much as possible while burning a mixed fuel of oil and water in a stable manner. It is an object of the present invention to provide an ignition device for a mixed fuel of oil and water that can perform continuous combustion and reduce NOx emissions.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a hollow spherical ceramic inner shell;
a metal outer shell surrounding the outer side of the inner shell via a heat insulating layer; a pair of electrodes provided in the inner space of the inner shell;
an alternating current power supply connected to the pair of electrodes to cause plasma discharge between them; and an AC power supply formed by penetrating the inner shell and the outer shell to supply an inert gas or air from the outside to the inner space of the inner shell. An ignition device for a mixed fuel of oil and water includes a gas supply passage and a discharge hole that is also formed through the outer shell and the inner shell and discharges the gas in the internal space to the outside. .

[0007]

[Operation] In the ignition device for a mixed fuel of oil and water having the above structure, alternating current power is applied to the pair of electrodes to cause plasma discharge in the internal space of the ceramic inner shell. At this time, inert gas or air is continuously supplied to the internal space of the inner shell through the gas supply passage in order to facilitate generation of plasma discharge. Note that the inert gas or air supplied inside is exhausted to the outside from the exhaust hole. Additionally, when a plasma discharge occurs, the internal temperature of the ceramic inner shell becomes extremely high in a short period of time, and the heat is transferred to the metal outer shell covering the outside through the inner shell and the insulation layer. The outer shell is then heated to extremely high temperatures until it becomes incandescent. For this reason, when a spray of mixed fuel of oil and water is sprayed onto this incandescent outer shell, the mixed fuel flows in front of the outer shell without having to forcibly supply a large amount of combustion air with a blower or the like to stir it. The heat is removed on the downstream side and gasified to a state where combustion is possible, and the incandescent outer shell on the downstream side becomes a spark and ignites.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an ignition device for mixed fuel of oil and water according to the present invention, and FIG. 2 shows a light oil burner equipped with this ignition device. As shown in Figure 2, light oil burner 2
It consists of a pressure spray nozzle 4 that sprays a mixed fuel of oil and water in the form of droplets, a combustion tube 6, and an ignition device 8. The pressure spray nozzle 4 is disposed at one end of the combustion tube 6, and its nozzle port 4a faces the axis of the combustion tube 6. The ignition device 8 is disposed at the axial center of the combustion tube 6 and is attached to the combustion tube 6 via a support member 10 .

As shown in FIG. 1, the ignition device 8 includes an inner shell 12 made of ceramic and formed in the shape of a hollow sphere, and a metal shell 12 surrounding the outer side of the inner shell 12 with a heat insulating layer 14 interposed therebetween. It has an outer shell 16. In this embodiment, tungsten with a thickness of about 3 mm is used for the outer shell 16,
Its outer diameter is approximately 70 mm. Powdered mica is used for the heat insulating layer 14, and the thickness thereof is also approximately 3 mm. Also, the inner shell 12
The thickness is approximately 10 mm.

A pair of electrodes 20 and 22 which pass through the spherical inner shell 12 and the outer shell 16 and face the internal space 18 of the inner shell 12 are provided at the upper and lower ends of the spherical inner shell 12 and outer shell 16, respectively, facing each other. It is being One electrode 20 disposed at the lower end is connected to the inner shell 1
2 and the outer shell 16 and are directly attached thereto, and the other electrode 22 is inserted and disposed within a cylindrical body 24 that penetrates the inner shell 12 and the outer shell 16 and is attached integrally thereto. has been done. The two electrodes 20 and 22 are made of tungsten, and a ceramic coating layer 26 is formed on the outer circumferential surface of the other electrode 22 on the upper end side except for the tip portion, and the tip portion is exposed from inside the cylinder 6. protrudes downward. The other electrode 22 passes through a lid 28 that closes the upper end of the cylindrical body 24 and is locked to the lid 28 .

The cylinder 24 has a cylindrical shape, and a ceramic coating layer 24b is formed on the inner and outer peripheral surfaces of a core material 24a made of tungsten. The inner diameter of the cylindrical body 24 is sufficiently larger than the outer diameter of the electrode 22, and an annular gas supply passage 30 is defined between them. Air is continuously blown in from a blower (not shown). The upper end of the cylinder 24 extends through the combustion tube 6 and is supported by the combustion cylinder 6 while projecting to the outside, and the cylinder 24 constitutes the support member 10 described above.

Further, the internal space 18 of the inner shell 12 is filled with conductive particles 34 up to a height close to the electrode 22 on the upper end side, and in this embodiment, tungsten particles 34 are used. ing. Furthermore, a discharge hole 36 is formed in the inner shell 12 and the outer shell 16 to pass through them and discharge the gas in the inner space 18 to the outside.

An AC power source 38 is connected to the two electrodes 20 and 22 to cause plasma discharge between them, and a voltage of 150 to 300 volts is supplied from this AC power source 38.
AC power with a voltage of about 5 amperes and a frequency of about 100,000 hertz is output.

In the light oil burner 2 constructed as described above, when AC power is supplied to the two electrodes 20 and 22 of the ignition device 8, a gap between the electrode 22 on the upper end side and the tungsten particles 32 filled in the inner shell 12 is generated. A discharge occurs in this inner shell 12
When air is continuously supplied from the supply passage 30 into the internal space 18 of the plasma generator, the discharge becomes a plasma discharge.

When plasma discharge occurs, the internal temperature of the ceramic inner shell 12 becomes extremely high in a short period of time, and the heat is transferred to the tungsten outer shell 16 covering the outer surface of the inner shell 12 and the heat insulating material layer 14. The outer shell 16 is heated to a temperature of 3,000 degrees Celsius and shines white. At this time, the electrode 22 on the upper end side is cooled by an air flow supplied through a gas passage outside the electrode 22 to facilitate plasma discharge.

Therefore, when a spray of mixed fuel of oil and water is sprayed from the pressure spray nozzle 4 onto the outer shell 16 heated to an extremely high temperature, a large amount of combustion air is forcibly supplied by a blower or the like. Even without stirring, the mixed fuel is vaporized by natural intake alone on the upstream side of the outer shell 16 to remove its heat and become sufficiently combustible, and then the incandescent part on the downstream side of the outer shell 16 becomes a spark and ignites. At this time, the temperature of the upstream side of the outer shell 16 is much lower than that of the downstream side due to the heat of vaporization being taken away by the mixed fuel spray, but the plasma discharge continues. If so, the amount of heat required to vaporize the mixed fuel spray into a combustible state is maintained sufficiently. In other words, even if nearly 20% water is mixed with oil, the mixed fuel is stably and continuously combusted, and the combustion air is only naturally aspirated and not excessively supplied by a blower, etc., so the amount of NOx emissions is minimized. reduced to

Furthermore, even if the temperature difference between the upstream side portion and the downstream side portion of the outer shell 16 becomes very large, the outer shell 16
Since there is a heat insulating layer 14 of mica powder between the inner shell 12 and the inner shell 12, cracks will not occur in the ceramic inner shell 12. That is, the heat insulating material layer 14 and the outer shell 16 are provided mainly for the purpose of protecting the inner shell 12 made of ceramics.

[0018] Furthermore, the melting point of tungsten is 3382 degrees Celsius.
Therefore, it is better to control the plasma discharge by turning on and off the alternating current power supply so that the temperature of the outer shell 16 is around 3000 degrees Celsius. Furthermore, if the air supplied to the internal space 18 of the inner shell 12 is replaced with an inert gas, plasma discharge is more likely to occur.

In this embodiment, an example was given in which the ignition device according to the present invention is employed in a light oil burner, but it goes without saying that the ignition device of the present invention can also be employed in a heavy oil burner. If used as a fuel, it is also possible to operate an internal combustion engine with a mixed fuel of oil and water.

[0020]

Effects of the Invention As explained in detail in the embodiments above, according to the ignition device for a mixed fuel of oil and water according to the present invention, the outer side of the ceramic inner shell formed in the shape of a hollow sphere is covered with a heat insulating material. It is covered with a metal outer shell with a layer in between, and a plasma discharge is generated between a pair of electrodes installed in the inner space of the inner shell, heating it to an extremely high temperature that the outer shell becomes incandescent. , it exhibits the following excellent effects. (1) If used as an ignition device for a burner, even if a mixed fuel of oil and water with a water mixing ratio of 8% or more is used, the spray of the mixed fuel can be sprayed onto the ignition device. , it is possible to vaporize the mixed fuel spray to a state where it can be combusted sufficiently and to perform stable and continuous combustion without forcibly supplying and stirring a large amount of combustion air with a blower, etc., Moreover, since the combustion air is only naturally aspirated and does not need to be excessively supplied by a blower or the like, the amount of NOx emissions can be reduced as much as possible. (2) It can be formed extremely compactly, so it can be used in the igniter of an internal combustion engine, and the internal combustion engine can be operated with a mixed fuel of oil and water.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing an embodiment of an ignition device for a mixed fuel of oil and water according to the present invention.

FIG. 2 is a side sectional view showing an example of a light oil burner equipped with an ignition device for mixed fuel of oil and water according to the present invention.

[Explanation of symbols]

12 Ceramic inner shell 14 Insulation layer 16 Metal outer shell 18 Internal space 20, 22 Electrode 30 Gas supply passage 36 Discharge hole 38 AC power supply

Claims (1)

[Claims] Claim 1: A hollow spherical ceramic inner shell, a metal outer shell surrounding the inner shell with a heat insulating layer interposed therebetween, and a pair of metal shells provided in the inner space of the inner shell. an electrode, an AC power supply connected to the pair of electrodes to cause a plasma discharge between them, and an inert gas or air formed by penetrating the inner shell and the outer shell and entering the inner space of the inner shell from the outside. a gas supply passage for supplying gas, and a discharge hole that is also formed through the outer shell and the inner shell and discharges the gas in the internal space to the outside. Mixed fuel ignition device.