JPS6294730A - Flameless burning method by electric discharge and its device - Google Patents

Abstract

PURPOSE:To be able to burn hydrocarbon gas without flame from the start by heating up burning catalyst to the reaction starting temp. by electric discharge with a piezoelectric element etc. CONSTITUTION:Starting catalyst 8 is placed at the inside of main catalyst 7. The starting catalyst 8 is composed of ceramic fiber-like aggregate of which constituent particles have diameters ranging from few micron to ten and several micron and which bears catalyst and its heat capacity is very small and its heat conductivity is also small. Scattering of sparks discharged from a discharge electrode 6 in front of the starting catalyst 8 produces a small explosion and flameless burning is started using energy generated by the small explosion as burning energy. Even if the small explosion produced by high voltage discharge sparks makes flame burning, flame in a hollow 5 does not extrude outside of the main catalyst the starting catalyst has backfire prevention effect owing to its composition of fiber-like catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for flameless combustion of fuel gas, particularly hydrocarbon fuel gas, by electric discharge.

[Conventional technology]

Conventionally, flameless combustion of fuel gas using a combustion catalyst has been carried out using hydrogen gas, methyl alcohol, and aldehydes. These combustions did not require any particular heating of the combustion catalyst, and combustion started at room temperature.

[Industrial application field]

Flameless combustion has a wide range of uses, including lighters, body warmers, and charcoal fires that can be used at sea, in the mountains, and other places with strong winds. However, products using flameless combustion are not very popular today.

The reason is.

(1) Hydrogen gas is dangerous to handle (2) Hydrogen gas is expensive (3) When methyl alcohol or aldehyde is used as a fuel, the water produced by combustion wets the catalyst and prevents the combustion reaction from occurring.

This was due to the following shortcomings.

The present invention focuses on this point and provides a method and device for starting flameless combustion by ignition by electric discharge using liquid butane used in commercially available lighters and gas stoves, propane, city gas, and other hydrocarbons as fuel. It is something.

[Problem that the invention seeks to solve]

The hydrocarbon fuel used in the present invention does not cause a combustion reaction at room temperature. For example, in order to combust a mixed gas of n-butane gas and air using a platinum catalyst, a temperature of at least approximately 180°C is required. Depending on the type of fuel gas, the reaction starting temperature may vary slightly from 150°C to 350°C. Although different, a combustion start temperature is required in any case.

This problem has been solved by heating the combustion catalyst to the combustion starting temperature through primary combustion using an electric heater or spark type. However, in order to use only one type of electric heater, a power source is required. If it is portable, it must be equipped with a battery.

Batteries have a large volume (not suitable for miniaturization), and are inconvenient because you may not notice that the battery has run out, and you may not be able to use it when needed.

Further, the spark type is not preferable because the structure becomes complicated and the cost increases.

[Means for solving problems]

The main purpose of the present invention is to start flameless combustion using a piezoelectric element or the like, using only discharge as a trigger, regardless of the electric heater type or spark type type.

Normally, when a piezoelectric element or a high-voltage transformer is used to generate an electric spark to ignite secondary combustion, flame combustion occurs even in the presence of a combustion catalyst, and flameless combustion cannot be achieved. However, when the temperature of the combustion catalyst rises, flameless combustion may occur in the middle, but it has been completely impossible to cause flameless combustion from the beginning.

In particular, flameless combustion could not be achieved from the beginning only by ignition by electric discharge.

[Conventional method]

The conventional method will be explained below with reference to the drawings.

Figure 1 shows a case in which fuel gas ■ and air ■ are made into a mixed gas by an air mixing ejector ■ without using a combustion catalyst.
Sparks are emitted from the discharge electrode ■ while flowing into the cavity ■ (which is electrically grounded with a metal case such as stainless steel).

If there is a large amount of air, the mixed gas will burn explosively, causing instantaneous misfire and combustion not continuing. If the amount of air is small, no explosion will occur, but if you reduce the air mixture ratio while causing discharge from the open side of the case, flame combustion will occur and combustion will continue, but as shown in Figure 2 ( If it is placed on the open side of the main catalyst 7, flame combustion can be obtained even if it is discharged inside the cavity.

If the purpose is to obtain flame combustion, Lord @Rikiho7
Although the purpose can also be achieved with a metal holster with holes drilled in all layers or in many layers, it is necessary to generate flame combustion for a few seconds to several seconds in order to obtain flameless combustion with a device with the structure shown in Figure 2. It is necessary to raise the temperature (about 180° C. or higher in the case of n-butane gas) until the main catalyst reaches a temperature sufficient to cause a flameless combustion reaction. Therefore, in the device with the structure shown in Fig. 2, flame combustion is always required before starting flameless combustion.
It would be desirable to be able to initiate flameless combustion in a manner that does not require any flame combustion.

FIG. 3 shows a diagram explaining the principle of the present invention.

A feature of the present invention is that a start catalyst is provided inside the main catalyst. The start catalyst 8 is made by supporting a catalyst on a ceramic fibrous aggregate having a diameter of several microns to more than ten microns, and is characterized by extremely small heat capacity and low thermal conductivity. Immediately before the start catalyst 8, the discharge ff1WA6 causes a spark to fly, causing a small explosion, and the energy generated by the small explosion is used to start flameless combustion. catalyst 8
A part of the temperature reaches the combustion start temperature locally.

- Even though the energy of a small explosion caused by a high-pressure discharge spark is small thermal energy, the starting catalyst has a small heat capacity and a low thermal conductivity, so it is locally 15
The temperature rises from 0°C to nearly 400°C, and flameless combustion starts around this local high temperature area, gradually spreading, and finally the temperature of the entire main catalyst reaches the combustion starting temperature. The fuel gas continues to burn flamelessly using the main catalyst as the main combustion catalyst. Even if a small explosion caused by a hot-pressure discharge spark 1ζ causes a million-flame combustion,
Since the start catalyst is a fibrous catalyst, it has a flashback prevention effect (
(arrestor effect), the flame inside the cavity (2) does not escape to the outside of the main catalyst.

Figure 4 shows the appearance of the main catalyst, with a honeycomb-shaped cope 7r on the carrier.
It is coated with alumina using ELITE and then coated with platinum catalyst to resist adhesion. The effect was comparable even when palladium, rhodium, etc. were used alone or in combination in place of the platinum catalyst. Further, as the carrier, a platinum group wire mesh such as a platinum wire mesh or a heat-resistant and oxidation-resistant nickel chromium alloy is used directly or after being coated with a ceramic.

Figure 5 shows the appearance of the starter catalyst, which exhibits a high-speed reaction, easily absorbs thermal energy, and has a large heat insulating effect. Furthermore, backfire prevention effect (arrestor effect)
It is extremely important as it also has the following.

The method for manufacturing the start catalyst 8 will be described below.

The start catalyst plays the role of a spark, and the conditions for a start catalyst are (a) small heat capacity;
b) Good insulation (very low heat diffusion, i.e.
The thermal conductivity is 0. Ql cal/cm -sec -'C
Otherwise, the absorbed heat will be lost by thermal diffusion,
Experiments have shown that the temperature at which the catalytic reaction begins cannot be reached. (c) Heat resistance (1000'C-1600'
(c)), (d) capable of supporting a catalyst, and (e) resistant to thermal shock.

Example 1゜The starting catalyst was 3 to 1 of alumina fiber and silicon carbide fiber.
Chloroplatinic acid Hm (pt
Add C1・) at 2% volume ratio, soak alumina fiber or silicon carbide fiber, and heat at 45 to 60'C for 24 hours.
After drying at 20° C. to 150° C. for 3 hours, the mixture was fired and reduced at 200° C. to 300° C. in a hydrogen stream to prepare a starter catalyst.

Example 2゜Silicon rock fibers are made into short fibers of about 3 to 20 mm, and water is used as a solvent to prepare high-temperature ceramic materials (alumina, clay).

A mixture of silica stone, a binder, and a dispersant) is mixed well and papered with a wire mesh to obtain a thin Japanese paper-like film. This was dried at 45 to 60°C for 24 hours and then calcined at 1200 to 160°C to support a catalyst in the same manner as in Example 1.

The composition of the high temperature ceramic material is as follows.

Silicon carbide fiber (length 5-15TMA) 1
00g water
20jγ-alumina
140g clay powder
100g triethanolamine
10g gum arabic
20 g Polyvinyl alcohol (PVA) Aggregation degree 1400 10 g Alumina sol 120 g A catalyst support obtained by using the above material and carrying a catalyst by the method of Example 1 was tested for 240 hours as a result of a catalytic combustion test using n-butane gas. It did not deteriorate even after continuous combustion. Furthermore, the catalyst was found to not fall off because the intertwined portions of the fibers are fused with ceramics, so they do not come undone during use.

Example 3 A sectional view of a flameless combustion apparatus using the method of the present invention is shown in FIG.

The start catalyst 8 and main catalyst 7 manufactured according to Examples 1 and 2 were arranged as shown in FIG. It is designed so that it is ejected from the pinhole plate 11 with many holes of 50 to 80 μm at a high speed of 200 to 340 m/sec to the air mixing ejector 3, mixes with the inhaled air, and becomes an explosive state. By discharging this steamy mixed gas from the quadrupole 6, the mixed gas causes a small explosion in the cavity 5, and the explosion causes carbon
Due to the generated heat, the start catalyst 8 heated to the combustion start temperature starts flameless combustion, then the main catalyst 7 reacts,
Full-scale flameless combustion reaction continues.

FIG. 7 is an application example of FIG. 6.

This is an embodiment in which an exhaust port 12 is provided at the tip of the soldering iron shown in FIG. 6, a heat collector 13 made of copper or the like is attached, and a soldering iron tip 14 is further attached, which is applied to a soldering iron.

FIG. 8 shows an example of application to a gas lighter, in which a fuel gas tank 16. Piezoelectric element 17
2. The flameless combustion device of the present invention is built-in, and the high voltage terminal 18 and piezoelectric element 17 are connected by a high voltage cable 19, and the fuel gas tank 16 and fuel gas pulp 20 are connected by a fuel gas pipe 2.
1 to supply fuel.

When the push button 22 is pushed downward, the protrusion 23 pushes down one end of the pulp opening/closing seesaw 24 and raises the other end, so that fuel enters the device of the present invention from the fuel gas pulp 20 and the pressure is 1! When the element is struck, the high-voltage electricity generated discharges and ignites, starting flameless combustion.

The present invention, as described above, relates to the basic principle and device related to flameless combustion, and its application range is wide ranging from household goods to the field of production technology (its industrial contribution is significant).

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the ignition phenomenon when no combustion catalyst is used. FIG. 2 is a diagram explaining the ignition phenomenon when only the main catalyst is used. FIG. 3 is a diagram explaining the principle of the present invention. Figure 4 is an external view of the main catalyst. FIG. 5 is an external view of the start catalyst. FIG. 6 shows the device of the present invention. FIG. 7 is a diagram showing an embodiment in which the present invention is applied to a soldering iron. FIG. 8 is a diagram showing an embodiment in which the present invention is applied to a gas lighter. l...Fuel gas 2...Air 3...Air-fuel/mixture executor 4...Case
5... Cavity 6... Discharge electrode 7... Main catalyst 8... Start A [9... Filter 10...
O-ring 11... Pinhole plate 12...
Wandering port 13... Heat collector 14... Soldering tip 15... Decorative case 16... Fuel gas tank 17... Piezoelectric element 18... High voltage terminal
19...High voltage cable 20...Fuel gas pulp 21...Fuel gas pipe 22...Pun button
23... Protrusion 24... Pulp opening/closing seesaw Figure 8 Procedural amendment road (spontaneous) January 23, 1985 Commissioner of the Patent Office 111. Zl, 1, Indication of the case 1985 Patent Application No. 234869 3,
Relationship with the case of the person making the amendment Patent applicant 4 Number of inventions increased by amendment 15
, Subject of amendment 1) Claims section of the specification for the deaf l) Amendments to the claims of the specification are as shown in the attached sheet. 2) The amendment to the detailed description of the invention in the specification is as follows. (b) On page 3, line 5, insert ``When the water is cooled after use'' after ``When used,'' in ``Water generated by combustion when used.'' (b) On page 3, line 9, in the 14th character on the left, "body" was changed to "ka". On page 6, line 6, there was a 1 after "A catalyst was prepared." Note that only the start catalyst 8 was used and the main catalyst was not used. Even when tested without use, it was found to be sufficiently durable for use. ” is inserted. 2. Claims (1) A method for flameless combustion of hydrocarbon gas from the beginning by electric discharge using a piezoelectric element or the like in a cavity having a catalyst at one end. (2) A mixture of fuel gas and air is introduced from one end of the cavity, and a layer of platinum group catalyst with a &ffl male heat-resistant material (e.g. alumina fiber) as a carrier is used as a starting catalyst at the other end. Catalysts are supported on X- or heat-resistant and oxidation-resistant (e.g. nickel chromium alloy) metal alloy meshes made of ceramics (e.g. honeycomb cordierite) or platinum group metals coated with ceramics such as platinum group metals or alumina. It has a double structure with the main catalyst, and a small explosion is induced by the discharge from the discharge hole provided in the cavity, and the energy generated by the small explosion is used as the energy to start the catalytic reaction, A flameless combustion device characterized by starting flameless combustion using a catalyst. (3) Entwining ceramic fibers, melting and adhering the fiber contacting or intersecting portions with ceramics,
A starter catalyst made of a porous structure with air permeability and supporting a catalyst. (4) A flameless combustion method and device using electric discharge for the purpose of claim (1) using only a start catalyst.

Claims (3)

[Claims] (1) A method in which the combustion catalyst is heated to the combustion reaction initiation temperature by electric discharge using a piezoelectric element, etc., and the hydrocarbon gas is flamelessly combusted from the beginning. (2) A mixture of fuel gas and air is introduced from one end of the cavity, and a fibrous heat-resistant material (for example, alumina fiber) is introduced into the other end.
A layer of platinum group catalyst supported on a ceramic (e.g. honeycomb cordierite) having many through holes, a mesh made of a platinum group metal, or a heat-resistant and oxidation resistant (e.g. nickel chromium alloy) metal alloy mesh with a platinum group metal or It has a double structure with a starter catalyst that supports a catalyst on a ceramic coated with alumina, etc., and a small explosion is caused by the discharge from the discharge electrode installed in the cavity, which causes a small explosion. A flameless combustion device characterized in that combustion energy is used to start flameless combustion. (3) A starter catalyst in which ceramic fibers are entwined and the fiber contacting or intersecting portions are melted and bonded with ceramics to form a porous structure having air permeability and supporting a catalyst.