JP3702348B1 - Solid fuel combustion method, solid fuel combustor, and solid fuel engine using the same - Google Patents

Abstract

Provided is a solid fuel combustion method using a solid plastic fuel that is incombustible as a solid fuel but has a strong combustion thermal power when burned out. An electromagnetic wave is radiated to a layer liquefied by heating a plastic solid fuel, the liquid fuel is heated and vaporized at once by the electromagnetic wave, and the vaporized fuel is burned to obtain a powerful combustion thermal power. Solid fuel combustion method. Flame retardant plastics can be used as solid fuel, resulting in a large combustion firepower. In addition, since flame retardant plastic is used as fuel, it is extremely safe (because it is difficult to burn) and is easy to handle.
[Selection] Figure 1

Description

  The present invention relates to a solid fuel combustion method, a solid fuel combustor, and a solid fuel engine using the solid fuel combustion method. The present invention relates to a solid fuel combustion method, a solid fuel combustor, and a solid fuel engine using the same.

  Conventionally, a rocket engine using a solid fuel is known (Patent Document 1).

JP 2000-186620 A

  The rocket engine described in Document 1 includes a combustor 102 having a nozzle 103 as shown in FIG. 6, and a solid fuel 106 is provided in a cylindrical shape in a combustion chamber 105 in the combustor 102. The combustor 102 is connected via a pump 104 to a tank 101 filled with a liquid oxidant. In this engine, a solid fuel 106 is ignited by an ignition body (not shown), a liquid oxidant is supplied from a pump 104 to burn the solid fuel 106, and a combustion gas is injected from a nozzle 103 to obtain thrust. It has become.

In recent years, attempts have been made to use plastic (acrylic, PMMA, etc.) as a solid fuel in the rocket engine as described above.
The plastic solid fuel has advantages such as being able to obtain a very large combustion thermal power if it can be burned in a good combustion state, and being excellent in safety in handling the fuel.

However, due to the nature of this fuel itself, the following problems have been pointed out.
In other words, plastic fuel is known to burn while undergoing a phase change from solid to liquid to gas. However, it takes time to change the phase from solid to gas. Combustion is unlikely to occur. Therefore, when plastic is used as the fuel for the engine, the combustion speed is slow (that is, it is difficult to burn), and sufficient thrust as the engine cannot be obtained. In addition, in order to improve the combustibility of the solid fuel, there are some in which combustible metal fine powder (for example, Al) is mixed in the solid fuel. However, such a fuel tends to burn, but there is a risk in terms of safety. There is also a problem that it increases and handling becomes difficult. For this reason, at present, the practical application of engines using plastic as a solid fuel is delayed.

  Apart from the above, development of an ignition technique using electromagnetic waves (microwaves) having a frequency of several gigahertz has been promoted for the purpose of eliminating electromagnetic noise generated for ignition of the air-fuel mixture in an internal combustion engine. (Patent Document 2).

JP 2000-230426 A

With the background of the combustion technology as described above, the present inventors conducted extensive research on a technology for rapidly burning plastic fuel, and as a result, radiated electromagnetic waves when the plastic solid fuel is in a phase-change state. It was found that the liquid fuel can be heated and vaporized and the phase change from liquid to vaporization can be accelerated rapidly.
The present invention has been made on the basis of the above knowledge, and by radiating electromagnetic waves to a layer liquefied by heating a plastic solid fuel, the liquid fuel is heated and vaporized at once by electromagnetic waves, and the vaporized fuel is burned. An object of the present invention is to provide a solid fuel combustion method, a solid fuel combustor, and a solid fuel engine using the solid fuel combustion method capable of obtaining a powerful combustion thermal power.

Therefore, the technical solution adopted by the present invention is:
A solid fuel combustion method characterized in that a solid fuel made of plastic is heated and liquefied to radiate electromagnetic waves to heat and vaporize the fuel to burn the vaporized fuel.
The electromagnetic wave radiation is performed by a coaxial fuel cable embedded in a solid fuel.
In the solid fuel combustion method, either an electromagnetic wave receiving antenna or an electromagnetic wave oscillator is connected to the coaxial cable.
The solid fuel combustion method is characterized in that an oxidant is supplied toward the solid fuel combustion section to burn the solid fuel.
Also, a combustor that stores a solid fuel made of plastic, a heating unit that heats the solid fuel stored in the combustor, and an electromagnetic wave emission unit that radiates electromagnetic waves toward a phase in which the solid fuel is heated and liquefied. An electromagnetic wave oscillator for supplying an electromagnetic wave to the electromagnetic wave radiating means, and heating the solid fuel in the combustor to radiate an electromagnetic wave to a liquefied phase to promote fuel vaporization and accelerate combustion. Is a solid fuel combustion apparatus characterized by
The electromagnetic wave radiation means is constituted by a coaxial cable, and a plurality of the coaxial cables are arranged in the solid fuel.
Further, the electromagnetic wave radiation means is a solid fuel combustion apparatus comprising an electromagnetic wave receiving device and configured to receive an electromagnetic wave from an electromagnetic wave oscillator wirelessly.
The solid fuel combustion apparatus further includes an oxidant supply means for supplying an oxidant to the solid fuel combustion portion of the combustor.
Further, in a solid fuel type engine comprising an oxidant supply means, a combustor connected to the oxidant supply means, and a nozzle continuously provided in the combustor, the engine supplies a solid fuel made of plastic. A combustor to be housed; heating means for heating the solid fuel housed in the combustor; electromagnetic wave radiation means for radiating an electromagnetic wave toward a phase in which the solid fuel is liquefied by the heating means; and the electromagnetic wave An electromagnetic wave oscillator for supplying electromagnetic waves to the radiating means, radiating electromagnetic waves to a phase in which the solid fuel in the combustor is liquefied, promoting vaporization of the fuel, and accelerating the combustion of the solid fuel It is a solid fuel engine.
The electromagnetic wave radiating means is constituted by a coaxial cable, and a plurality of the coaxial cables are arranged in the solid fuel.

According to the present invention, an electromagnetic wave is radiated to a phase liquefied by heating a plastic solid fuel using a coaxial cable, the vaporization of the liquid fuel is promoted, and the vaporized fuel is combusted at a time as follows. Such unique effects can be achieved.
(1) A flame-retardant plastic can be used as a solid fuel, and as a result, a large combustion thermal power can be obtained.
(2) Since flame retardant plastic is used as fuel, it is extremely safe (because it is difficult to burn) and is easy to handle.
(3) By using a coaxial cable as a means for radiating electromagnetic waves, the metal in the coaxial cable is burnt at the same time when the solid fuel is burned, and the burning power of the flame-retardant plastic is increased.
(4) By transporting electromagnetic waves with a coaxial cable, it is possible to heat the object to be heated with an extremely high energy density as compared with the case of transporting using a normal waveguide.
(5) Since the coaxial cable is used, the shape of the combustion chamber can be designed freely.
(6) Combustion start (ignition) can be performed by electromagnetic waves.
(7) The combustion state can be measured and controlled by monitoring the output characteristics (voltage value, current value, etc.) of the electromagnetic wave oscillator.
(8) The combustion speed of the fuel can be locally changed by the arrangement of the coaxial cable.
(9) By controlling the electromagnetic wave intensity supplied to the coaxial cable arranged as appropriate, the thrust (propulsive force) intensity and direction of the hybrid rocket can be controlled.
(10) Since the combustion thermal power is strong, the fuel used can be greatly reduced.
(11) Since the combustor and the like can be reused, the cost of the apparatus can be greatly reduced.

A solid fuel made of plastic is stored in a combustor, and the solid fuel stored in the combustor is heated to emit an electromagnetic wave toward the liquefied phase of the solid fuel when the solid fuel burns. Thus, the solid fuel combustion method and the solid fuel combustor are characterized by accelerating the vaporization of the fuel and accelerating the combustion.

1 is a cross-sectional view of the solid fuel combustor, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1, and FIG. 3 is a cross-sectional view of the solid fuel combustor according to the present invention. It is sectional drawing which shows the other example corresponding to FIG.
In FIG. 1, reference numeral 1 denotes an oxidant tank, and the oxidant tank 1 is connected to a combustor 3 via a control valve 2. The oxidant tank 1 is appropriately provided with an oxidant releasing means (for example, tank 1 pressurizing means) for releasing the oxidant, and these constitute an oxidant supply means.

  The combustor 3 has a cylindrical shape like a conventionally known one, and a solid fuel 4 (plastic fuel, for example, acrylic, PMMA, etc.) is arranged in a cylindrical shape as shown in the figure. A solid fuel heating means (not shown) (for example, an electric heater) is disposed outside the solid fuel 4 as necessary so that the solid fuel 4 can be appropriately heated. In the solid fuel 4, a plurality of coaxial cables 5 are arranged at appropriate intervals in the radial direction and the length direction of the solid fuel 4 as shown in FIGS. 1 and 2. The coaxial cable 5 can radiate electromagnetic waves from one end of the cable 5 toward the inner surface of the solid fuel 4.

The solid fuel 4 is provided with ignition means (not shown) similar to the conventional one.
In addition, as an ignition means, an ignition means can be adopted in which an electrode is disposed opposite to one end of the coaxial cable 5 as necessary, and the solid fuel 4 can be directly ignited by discharge (spark) with the electrode. You can also. In this case, it is not necessary to arrange the electrodes so as to oppose one end side of all the coaxial cables 5, and the electrodes can be provided at a portion corresponding to the ignition position of the solid fuel 4.

An electromagnetic wave transmitter 6 or an antenna for receiving electromagnetic waves is connected to the other end side (outside of the combustor 3) of the coaxial cable 5. The receiving antenna is configured to receive an electromagnetic wave oscillated from an electromagnetic wave transmitter (not shown) arranged away from the combustor 3 and radiate the electromagnetic wave from one end of the coaxial cable 5 toward the solid fuel 4. ing. Further, when the electromagnetic wave transmitter and the coaxial cable 5 are directly connected, the electromagnetic wave oscillated from the transmitter is radiated from one end of the coaxial cable 5.
Further, the electromagnetic wave oscillator (not shown) can be provided with monitoring means for monitoring the output characteristics (voltage value, current value, etc.) of the electromagnetic wave oscillator. For example, when solid fuel burns, the length of the coaxial cable changes accordingly. From this, the length of the coaxial cable = representing the remaining amount of solid fuel. The state can be measured and controlled. It is also possible to change the solid fuel combustion state by changing the energy intensity of the electromagnetic wave supplied to the coaxial cable. In addition, as an electromagnetic wave to radiate, a frequency in the range of 3 kHz to 300 GHz is effective.

  In the case of this example shown in FIG. 1, the oxidant can be directly supplied from the oxidant tank 1 to the combustor via the control valve 2, but the oxidant tank 1 is not pressurized. It is also possible to connect a tank and supply the oxidant to the combustor 3 by the applied pressure. The oxidant is supplied into the combustor 3 manually or automatically via the control valve 2 according to the combustion state.

FIG. 3 is a view showing another arrangement example of the coaxial cable 5.
In the case of this figure, one coaxial cable 5 is spirally arranged in the solid fuel 4, and if necessary, a plurality of coaxial cables 5 can be arranged at appropriate intervals in the length direction of the solid fuel 4. . Further, as in the case of FIG. 2, it is also possible to arrange an electrode facing the end of the coaxial cable 5 and also serve as an ignition means. Further, it is possible to locally change the combustion speed of the fuel by devising the arrangement of the coaxial cable.
2 and FIG. 3 is an outer wall of the combustor 3.

The operation of the combustor 3 having the above configuration will be described.
The solid fuel 4 is heated by heating means. In this state, the solid fuel 4 is ignited by the ignition means. When an electrode is disposed opposite one end of the coaxial cable 5 as an ignition means, an electromagnetic wave is transmitted to the coaxial cable 5, and as a result, the solid fuel 4 is ignited using a spark generated between the electrodes. . In the case of an ignition means (not shown) using a nichrome wire, the solid fuel 4 can be directly ignited by passing a current through the nichrome wire. When the oxidant is supplied from the oxidant tank 1 through the control valve 2 substantially simultaneously with the operation of the ignition means, the solid fuel 4 starts to burn. When the solid fuel 4 burns, the solid fuel 4 is heated by the heat, and the solid fuel 4 in the vicinity of the combustion portion of the solid fuel 4 is liquefied. In this state, the liquid phase fuel is heated by the electromagnetic waves radiated from the coaxial cable 5, vaporization is promoted, and the solid fuel 4 is burned at once. In this way, the plastic fuel having flame retardance easily burns, and a strong burning power can be obtained.

Next, an embodiment of a hybrid rocket engine using the solid fuel combustor 3 will be described. 4 is a sectional view of the engine, and FIG. 5 is a sectional view showing another embodiment. The same reference numerals are used for the same members as in FIG.
As shown in the figure, the hybrid rocket engine includes a pressurizing tank 7, and the pressurizing tank 7 is connected to the oxidant tank 1 via a pressure regulating valve 8. The oxidant tank 1 is connected to the combustor 3 via the control valve 2.

  The combustor 3 has a cylindrical shape like a conventionally known one, and a nozzle 9 is provided at one end thereof. A solid fuel 4 (plastic fuel, such as acrylic or PMMA) is arranged in a cylindrical shape inside the combustor 3. Further, a solid fuel heating means (not shown) (for example, an electric heater) is disposed outside the solid fuel 4 as necessary, so that the solid fuel 4 can be appropriately heated. In addition, a plurality of coaxial cables 5 are arranged in the solid fuel 4 at appropriate intervals in the radial direction and the length direction of the solid fuel 4 as shown in FIG. 4 can be emitted. Since the arrangement of the coaxial cable 5 is the same as that of the combustor 3 described above, further explanation will be omitted. However, the arrangement of the coaxial cable is devised and the energy intensity of the electromagnetic wave supplied to the coaxial cable is changed. It is also possible to change the combustion speed of the engine and to control the thrust direction of the engine.

If necessary, an electrode constituting the ignition means is arranged opposite to one end of the coaxial cable 5 so that the solid fuel 4 can be directly ignited by discharge (spark) with the electrode. In this case, it is not necessary to arrange the electrodes so as to face one end side of all the coaxial cables 5, and it is preferable to provide the electrodes at a portion corresponding to the ignition position of the solid fuel 4.
An electromagnetic wave transmitter 6 is connected to the other end of the coaxial cable 5, and an electromagnetic wave oscillated from the electromagnetic wave transmitter is radiated from one end of the coaxial cable 5.

The operation of the hybrid rocket engine having the above configuration will be described.
The solid fuel 4 is heated by heating means. In this state, the solid fuel 4 is appropriately ignited by ignition means. When an electrode is disposed opposite one end of the coaxial cable 5 as an ignition means, an electromagnetic wave is transmitted to the coaxial cable 5, and as a result, the solid fuel 4 is utilized by using a discharge (spark) generated between the electrodes. Ignite. Further, the solid fuel 4 can be directly ignited by ignition means such as nichrome wire. When the oxidant is supplied from the oxidant tank 1 through the control valve 2 substantially simultaneously with the operation of the ignition means, the solid fuel 4 starts to burn. When the solid fuel 4 burns, the solid fuel 4 is heated by the heat, and the solid fuel 4 in the vicinity of the combustion portion of the solid fuel 4 is liquefied. In this state, the liquid fuel is heated by the electromagnetic waves radiated from the coaxial cable 5, vaporization is promoted, and the solid fuel 4 is burned at once. The combustion gas combusted in the combustor 3 is injected from the nozzle 9, and a strong propulsive force can be obtained. Thus, the plastic fuel having flame retardancy can be used as the fuel for the rocket engine, and the engine thrust and the safety of fuel handling can be improved.

  FIG. 5 is a modification of FIG. 4, in which an electromagnetic wave transmitter 11 is attached to each coaxial cable 5 disposed in the solid fuel 4. Instead of the electromagnetic wave transmitter 11, an antenna for receiving electromagnetic waves can be used. The operation of the hybrid rocket engine in this figure is the same as in FIG.

Although the embodiment of the present invention has been described above, the oxidant supply means is not essential as a solid fuel combustor and can be omitted as appropriate. Also, other means can be adopted as long as the arrangement of the coaxial cable and the electromagnetic wave supply means can obtain the same effect. The shape of the combustor and the shape of the solid fuel are not limited to the cylindrical shape described above, and various shapes can be adopted, and the solid fuel can be adapted to the shape of the combustor. In this case, the coaxial cable is arranged at a position most effective for electromagnetic wave radiation.
In addition, the present invention can be implemented in various other forms without departing from the spirit and main features thereof. For this reason, the above-described embodiments are merely examples, and should not be interpreted in a limited manner. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  The present invention can be used as various combustors such as various engines and stoves.

It is sectional drawing of the solid fuel combustor which concerns on this invention. It is AA sectional drawing in FIG. It is sectional drawing which shows the other example corresponding to FIG. It is sectional drawing of a hybrid rocket engine. It is sectional drawing which shows the other Example of a hybrid rocket engine. It is a block diagram of the conventional hybrid rocket engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oxidant tank 2 Control valve 3 Combustor 4 Plastic solid fuel 5 Coaxial cable 6 Electromagnetic wave oscillator 7 Pressurized tank 8 Pressure regulating valve 9 Nozzle 10 Outer wall of combustor

Claims (10)

A solid fuel combustion method, comprising: heating a solid fuel made of plastic to a liquefied phase by radiating electromagnetic waves to heat and vaporize the fuel, and burning the vaporized fuel. 2. The solid fuel combustion method according to claim 1, wherein the radiation of the electromagnetic wave is performed by a coaxial cable embedded in the solid fuel. 3. The solid fuel combustion method according to claim 1, wherein either an electromagnetic wave receiving antenna or an electromagnetic wave oscillator is connected to the coaxial cable. The solid fuel combustion method according to any one of claims 1 to 3, wherein the solid fuel is burned by supplying an oxidant toward the solid fuel combustion section.
A combustor for storing a solid fuel made of plastic, a heating means for heating the solid fuel stored in the combustor, an electromagnetic wave emission means for radiating electromagnetic waves toward a phase in which the solid fuel is heated and liquefied, and An electromagnetic wave oscillator for supplying an electromagnetic wave to the electromagnetic wave radiation means, and heating the solid fuel in the combustor to radiate the electromagnetic wave to a liquefied phase to promote fuel vaporization and accelerate combustion. Solid fuel combustion device. 6. The solid fuel combustion apparatus according to claim 5, wherein the electromagnetic wave radiation means is constituted by a coaxial cable, and a plurality of the coaxial cables are arranged in the solid fuel. 7. The solid fuel combustion apparatus according to claim 5, wherein the electromagnetic wave radiating means includes an electromagnetic wave receiving device, and is configured to receive an electromagnetic wave from an electromagnetic wave oscillator wirelessly. 8. The solid fuel combustion apparatus according to claim 5, further comprising an oxidant supply unit configured to supply an oxidant toward the solid fuel combustion portion of the combustor. 9.
In a solid fuel type engine comprising an oxidant supply means, a combustor connected to the oxidant supply means, and a nozzle continuously provided in the combustor, the engine stores solid fuel made of plastic. A combustor, a heating means for heating the solid fuel stored in the combustor, an electromagnetic wave radiation means for radiating an electromagnetic wave toward the phase liquefied by the solid fuel heated by the heating means, and the electromagnetic wave radiation means An electromagnetic wave oscillator for supplying electromagnetic waves to the solid fuel, radiating electromagnetic waves to the liquefied phase of the solid fuel in the combustor, promoting vaporization of the fuel, and accelerating the combustion of the solid fuel Expression engine. 10. The solid fuel engine according to claim 9, wherein the electromagnetic wave radiating means is constituted by a coaxial cable, and a plurality of the coaxial cables are arranged in the solid fuel.

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