JP2003071419A - Thermal decomposition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burning device with a simple structure and at a low operation cost capable of thermally decomposing wastes to the approximately atomic state by heating them at a higher temperature. SOLUTION: In a thermal decomposition chamber 1, the inside is covered with a refractory material 2 and a throwing port 3 for the wastes or the like and a discharge port 4 for discharging the gas produced by thermally decomposing the wastes or the like are provided. In the thermal decomposition chamber 1, three heating part 11A to 11C in which a large number of heat generation bodies 10, comprising a carbonaceous substance, of which an outer surface is covered with metal are interposed between electrodes 7a to 7f are arranged in series. When a power is fed to the electrodes 7a to 7f from a power source 8, arc discharge is generated between the electrodes and the heat generation bodies 10 or between the heat generation bodies to generate heat. Accompanying with this, an electric resistance of the carbonaceous substance is rapidly reduced and a feed current is rapidly increased to also strengthen a resistance generation heat. As a result, the high temperature of 2,000 deg.C or higher is obtained. The waters are thermally decomposed at the first heating part 11A, made to the gaseous state at the second heating part 11B and certainly decomposed to the atomic state at the third heating part 11C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal decomposition apparatus for thermally decomposing general waste such as municipal waste and industrial waste discharged from factories such as oil at a high temperature to convert it into a harmless substance.

[0002]

2. Description of the Related Art Conventionally, incinerators have been used for detoxifying, reducing and reducing the volume of waste, and the waste is often burned and converted into gas or ash. It is said that the combustion temperature of this waste is usually 900 ° C. or higher, and it is desirable to be 1100 ° C. or higher when incinerating PCBs.
It is operated at a temperature slightly above these. To obtain these combustion temperatures, incinerators use coke, gas, kerosene,
Fuels such as heavy oil are mainly used, but there are some that use electricity such as electric resistance heating, arc discharge, and plasma discharge.

[0003]

Among the above-mentioned conventional refuse incinerators, the type that burns fuel has a low incineration temperature, which is only about 1000 ° C., so that the waste heat The decomposition is not sufficient, and it remains as a molecular substance with a considerable number of atoms bound, which not only causes problems for this treatment but also produces harmful substances such as dioxins due to chemical reaction again in the cooling process after combustion. is there. On the other hand, in the type using electricity, the resistance heating process is inefficient and the operating cost is high, and the arc discharge process can only discharge heat between narrow electrodes and can process only a small amount of waste. In addition, the plasma discharge treatment cannot avoid increasing the size and cost of the device, and the plasma itself has an extremely high temperature of 6000 ° C, but it is only a small portion, and is 1500 ° C or less as a whole. It often becomes.

The present invention provides a thermal decomposition apparatus which has a low operating cost and a simple structure, and heats wastes such as dust and harmful emissions at a higher temperature to decompose them into almost atomic states. The purpose is to provide.

[0005]

Therefore, the present invention according to claim 1 has a charging port for charging a waste and a discharging port for discharging a gas generated by thermally decomposing the waste. And a discharge port are covered with a heat-resistant material, a pyrolysis chamber capable of storing waste and gas, a power source capable of supplying electric power, and at least a pair of electrodes to which electric power is supplied from the power source. A heating unit having a plurality of heating elements formed of a carbonaceous substance capable of discharging and energizing, and at least three heating units provided, each heating unit extending from an inlet to an outlet. It is arranged in series in the pyrolysis chamber in a separated state.

According to a second aspect of the present invention, the power source is preferably configured so that the power supplied to the electrodes can be periodically switched between a high voltage and a low voltage.

According to the third aspect of the present invention, the cycle is preferably controlled to be shorter when the heating element is at a low temperature than when it is at a high temperature.

According to a fourth aspect of the present invention, it is preferable that one of the heating units is in an abnormal state in which one of them cannot be heated.
At least one of the remaining heating units is configured to be controlled to be switched to a higher temperature side than in the normal state.

According to a fifth aspect of the present invention, the heat generating element preferably diffuses and permeates a highly conductive metal on the outer surface of carbon.
Alternatively, it is formed by thermal spraying.

According to the sixth aspect of the present invention, the highly conductive metal preferably comprises at least one of chromium, molybdenum, aluminum, magnesium and tungsten.

In the invention of claim 7, the carbonaceous material is preferably charcoal or bamboo charcoal baked at about 2000 ° C. or higher.

[0012]

According to the first aspect of the present invention, when electric power is supplied from the power source to the electrodes, arc discharge is initiated between the electrodes and the heating element and between the heating element and the heating element. This arc discharge is the main cause of the heating element to generate high temperature heat. As the temperature of the heating element rises, the electrical resistance of the carbonaceous material that makes up the heating element decreases sharply, resulting in a sharp increase in the supply current and an increase in the amount of heat generated, increasing the temperature even more, making it easier and shorter. The temperature becomes a high temperature of 2000 ° C. or higher. When waste is put into the pyrolysis chamber in this state between the lowermost heating unit and the second heating unit from the bottom, the waste is thermally decomposed by radiant heat or the like emitted from both of them, for example, from a high temperature of 2200 ° C or higher. Then, the benzene ring and the like are cut off.

As described above, the substance is thermally decomposed into a gaseous substance or a fine substance in which chemical bonds are partially broken. These substances pass through the gap between the heating elements of the second heating unit and
While being heated to about ℃, gasification progresses further and rises further. In addition, here, a considerable part of the gas is thermally decomposed until it becomes an atom or almost an atomic state. In the third heating section, the gas is further heated at about 2500 ° C., and the gas discharged from the second heating section is almost completely converted into an atomic gas. That is, the gaseous substance is decomposed to almost an atomic substance, and the thermally decomposed substance remains in a larger molecular state, and recombines after heating to prevent generation of harmful substances such as dioxins.

According to the second aspect of the present invention, the power supply is controlled so that the supplied power is periodically switched between a high voltage and a low voltage. Therefore, arc discharge is desired according to the temperature state of the heating element. Can be controlled accordingly.

In the invention of claim 3, the cycle of the supply voltage is
When the temperature of the heating element is low, the cycle is controlled to be shorter than that at high temperature.Therefore, when the temperature of the heating element is low, the power supply cycle is short and arc discharge occurs frequently to improve the heating rate of the heating element. After the temperature of the heating element has risen and its electrical resistance has decreased, the power supply cycle can be lengthened to increase the amount of current flowing to the heating element and maintain a high heating value. It is possible to execute the optimum heat generation control of.

In the fourth aspect of the present invention, at the time of an abnormality in which one of the heating parts cannot be heated, at least one of the remaining parts is controlled to be switched to a higher temperature side than in the normal state. Even if the heating capacity of the waste is reduced, the heating temperature of other normal heating units is correspondingly increased, so that the waste or its pyrolyzed product is maintained at a high temperature and is substantially harmless. In this case, although the durability of the heating element of the heating unit for further heating tends to deteriorate earlier, it is possible to suppress the discharge of harmful substances.

According to the fifth aspect of the invention, the heating element is formed by diffusing, permeating, or spraying a highly conductive metal on the outer surface portion of the carbon-based material. Therefore, when the heating element is composed of only the carbon-based material. Compared with the above, even if an arc discharge is generated on the surface of the heating element, the loss is small and the durability of the heating element can be further improved.

According to the invention of claim 6, the good conductive metal is at least one of chromium, molybdenum, aluminum, magnesium and tungsten.
These metals are suitable for protecting the internal carbonaceous material from being damaged by arc discharge or being ashed by combustion even if the heating element is heated to 2000 ° C. or higher.

In the invention of claim 7, since charcoal or bamboo charcoal baked at a high temperature of about 2000 ° C. or more is used as the carbonaceous substance of the heating element, it can endure the high temperature at the time of heat generation and can be used for a long time. It will be possible. Further, it becomes possible to easily and inexpensively obtain the heating element.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on Examples. FIG. 1 shows a cross section of a combustion apparatus according to an embodiment of the present invention. In the figure, the thermal decomposition chamber 1 has a rectangular tubular shape and has a bottom portion 1a, and a refractory material 2 is provided inside. The refractory material 2 is a silicon-based material that is specially processed to have refractory properties.
The one described in Japanese Patent No. 82980 is used. Pyrolysis chamber 1
On the lower side of the, there is a waste input port 3 and also the thermal decomposition chamber 1
A discharge port 4 is provided above each. The inlet 3 can be opened and closed by a door (not shown).

In the thermal decomposition chamber 1, the refractory material 2 is provided on the bottom portion 1a in addition to the four side walls, and the first bottom plate 5a is placed on the refractory material 2. This bottom plate 5a
Is made of a ceramic material or metal. Inside the refractory material 2 serving as an inner wall, a flat plate-shaped first electrode 7a is provided on the left side wall in the drawing via an insulating member 6a, and this electrode 7a
The flat plate-shaped second electrode 7 facing the
b are attached to the right side wall in the figure, respectively. The first and second electrodes 7a and 7b are made of a material having good electrical conductivity and heat resistance, for example, a carbon-based material. As a carbon-based substance,
The same material as the heating element described later or graphite or the like is used. Electric cables 9a and 9b for supplying electric power from a power source 8 are connected to the first electrode 7a and the second electrode 7b, respectively.

A large number of heating elements 10 are interposed in the space surrounded by the two electrode plates 7a and 7b and the refractory material 2 on the bottom plate 5a. The heating element 10 is a carbon-based material, for example, about 2000 ° C.
The charcoal or bamboo charcoal baked as described above is formed into a spherical shape having a diameter of about 5 mm to 25 mm, and a highly conductive metal is diffused, permeated or sprayed on the outer surface portion of the charcoal or bamboo charcoal to cover it. At least one of chromium, molybdenum, aluminum, magnesium, and tungsten is used as the highly conductive metal. It is desirable that the surface of the heating element 10 has a large number of small projections formed on the entire surface of the metal covering the outer surface of the carbon-based material so that arc discharge is facilitated. In this way, the first heating unit 11A including the bottom plate 5a, the electrode plates 7a and 7b, the heating element 10 and the like is provided at the bottom of the thermal decomposition chamber 1.

A second heating unit 11B is provided above the first heating unit 11A and separated by a predetermined distance. This first
The space formed by the heating unit 11A and the second heating unit 11B can accommodate the waste that is put in from the input port 3 on the lower side surface of the thermal decomposition chamber 1. Similarly to the first heating unit 11A, the second heating unit 11B also has a flat plate-shaped third electrode 7 on the refractory material 2 serving as the inner wall of the thermal decomposition chamber 1 via the insulating member 6c.
c, and a flat plate-shaped fourth electrode 7d is mounted opposite to this via an insulating member 6d, and a large number of heating elements 10 are interposed therebetween. Third electrode 7c, fourth
Electric cables 9c and 9d are connected to the electrode 7d, and electric power can be supplied from a power source 8. A second bottom plate 5b is provided below the heating element 10 and the electrodes 7c and 7d to support the heating element 10. However, unlike the first bottom plate 5a, the second bottom plate 5b is different from the first bottom plate 5a. A large number of through holes 13a having a diameter smaller than that of the heating element 10 are formed, and a substance, a gas or the like having a diameter smaller than a predetermined diameter due to thermal decomposition of waste can pass through the through holes 13a.

A third heating unit 11C is provided above the second heating unit 11B at a position separated by a predetermined distance. Third
The heating unit 11C has the same structure as the second heating unit 11B, and the insulating member 6 is provided on the refractory material 2 which is the inner wall of the thermal decomposition chamber 1.
A flat plate-shaped fifth electrode 7e is attached via e, and a flat plate-shaped sixth electrode 7f is mounted opposite to this via an insulating member 6f, and a large number of heating elements 10 are interposed therebetween. To be done. Electric cables 9e and 9f are connected to the fifth electrode 7e and the sixth electrode 7f so that power can be supplied from a power source 8. A third bottom plate 5c is provided below the heating element 10 and both electrodes 7e and 7f to support the heating element 10. The third bottom plate 5c has the same structure as the second bottom plate 5b. A large number of through holes 13b having a diameter smaller than that of the heating element 10 are formed, and a substance, a gas or the like having a diameter smaller than a predetermined diameter due to thermal decomposition of the waste can pass through the through holes 13b.

Second heating section 11B and third heating section 11C
Between and and and above the third heating portion 11C, openings 14 and 15 for exchanging the heating element 10 are provided on the side surface of the inner wall of the thermal decomposition chamber 1 respectively. These openings 14 and 15 can be opened and closed by a door (not shown). A lid 16 is provided above the third heating unit 11C, and a substance or gas that has been thermally decomposed into an atomic form (or a molecular form having a small molecular weight) can be released from the discharge port 4 provided in the lid unit 16. is there. A discharge pipe 17 communicating with the discharge port 4 is connected to the lid 16. Discharge pipe 17
An air duct 18 for introducing air is attached to a side surface of the exhaust pipe 17 for discharging the air supplied by the blower 19.
It is possible to spit upwards inside. The discharge pipe 17 is provided with an opening 20 so that it can be opened and closed by a door (not shown).

The power supply 8 is provided with a cycle control section 21 capable of switching the power supplied to the electrodes 7a to 7f between a high voltage and a low voltage at a predetermined cycle. The cycle control unit 21 is, for example, of an inverter type, and when the temperature of the heating element 10 is low such as when heat generation starts, it is 50 to 1000.
When a voltage having a cycle of about Hertz is supplied to the electrodes 7a to 7f and the heating element 10 reaches a high temperature and reaches a predetermined temperature state, 10
The power source 8 is controlled so as to supply a voltage or constant pressure current reduced to about Hertz.

The operation of the thermal decomposition apparatus having the above structure will be described. In starting the thermal decomposition apparatus, the cycle control unit 21 controls the power supply 8 (here, 200 V is used) so that the cycle of switching the supply voltage between high and low is 100 Hertz, for example. In this way, the electric power from the power source 8 is transmitted through the electric cables 9a to 9f to the first heating unit 1
Electrodes 7a to 7f provided on 1A to third heating section 11C, respectively
Is supplied to. As a result, in the first heating portion 11A, between the electrode 7a and the heating element 10, between the heating elements 10 and between the heating element 10 and the electrode 7b, and in the second heating portion 11B, the electrode 7c and the heating element 10 are connected. And between the heating elements 10 and between the heating elements 1
Arc discharge occurs between 0 and the electrode 7d, between the electrode 7e and the heating element 10 in the third heating unit 11C, between the heating elements 10 and between the heating element 10 and the electrode 7f.

This arc discharge is likely to occur at the tip of the small protrusion of the heating element 10, and the heating element 10 is 5 mm to 25 m long.
It occurs most frequently when the diameter is about m. Small projections and electrodes 7a to 7 where arcs fly by arc discharge
The partial temperature of f becomes a high temperature of about 3000 ° C. to 6000 ° C., and the heating element 10 is heated. The arc discharge becomes more frequent due to the periodic change of the supply voltage. Although an electric current also flows through the carbonaceous material of the heating element 10, since the temperature of the heating element 10 is low and the electric resistance is high at the beginning of the start-up, resistance heating is small and heat is mainly generated by arc discharge. Similarly, resistance heating also occurs due to the contact resistance between the heating elements 10.

After a few minutes from the start, the temperature of the heating element 10 rises due to arc discharge and becomes high. As a result, the electric resistance of the carbon-based material sharply decreases, so that the current flowing through the carbon-based material sharply increases, and the resistance heating value also becomes very large.
The heating element 10 for generating heat as described above includes heating units 11A to 11A.
The temperature is controlled every 11C. Here, the first heating unit 1
1A is set to about 2200 ° C., and the second heating unit 11B and the third heating unit 11C are kept at about 2500 ° C., which is slightly higher than the first heating unit 11A. At this time, the carbon-based substance exerts a heat storage action. Further, the heat generation of the heating element 10 is performed without supplying air or oxygen into the thermal decomposition material 1.

On the other hand, when the heating parts 11A to 11C become high in temperature, the door of the charging port 3 is opened and the waste is charged into the space between the first heating part 11A and the second heating part 11B.
close the door. The waste receives radiant heat of about 2200 ° C. or higher from the first heating unit 11A and the second heating unit 11B, begins to be thermally decomposed, the chemical bond is partially broken and becomes a finer substance or a gaseous substance. It becomes. The thermally decomposed fine substance or gas passes through the through hole 13a of the bottom plate 5B, passes through the gap between the heating elements 10 of the second heating unit 11B, and is heated to about 2500 ° C. Here, breakage of chemical bonds and gasification proceed further. Here, a considerable part is thermally decomposed until it becomes atomic.

The solid substance and gas that have passed through the second heating unit 11B are further heated at about 2500 ° C. in the third heating unit 11C, and the solid substance and gas are almost completely converted into atomic gas. . In other words, the gaseous substance is decomposed to an atom or a state close to an atom, and not only does it prevent the generation of dioxin, but the thermally decomposed substance remains in a larger molecular state and is recombined after heating to cause dioxin etc. Prevent the generation of harmful substances. This gas is sucked by the air supplied from the air duct 17 and directed upward, and is raised from the exhaust port 4 toward the exhaust pipe 17. The gas discharged from the discharge pipe 17 to the outside is rapidly cooled.
The temperature has dropped to about 0 ° C.

The above is the operation during normal operation, but in the unlikely event that one of the heating sections fails during processing and heat generation is impossible, for example, when the second heating section 11B fails. The heating temperature of the third heating section 11C is set to 2700 ° C.
Raise up to about 3000 ° C or higher. This makes it possible to render the harmful substances almost harmless with only two heating parts. In this case, since the durability of the heating element 10 used in the third heating unit 11C deteriorates earlier, the heat-generating body 10 should be replaced with a new one as soon as possible after the completion of the thermal decomposition process. In addition, since the heating element uses a carbon-based material, if the failure occurs after heating to a high temperature even in the failed heating unit, the heating effect of the carbon-based material will help heat the waste for a while. be able to.

As is apparent from the above description, in the thermal decomposition apparatus of this embodiment, a large number of heating elements each having a carbon-based substance covered with a metal are interposed between electrodes to cause arc discharge and to generate electric power when the heating elements reach a high temperature. Since a large amount of current is made to flow in the carbonaceous material whose resistance decreases sharply and resistance heating is also used, a high temperature of 2000 ° C. to over 3000 ° C. can be obtained with a simple device and at low cost. Then, a heating unit having a heating element capable of obtaining such a high temperature is provided in
Since they are arranged in series, the waste substances are first thermally decomposed in the first stage, almost completely vaporized in the second stage, and decomposed into atomic substances in the third stage to be purified. Therefore, the generation and re-generation of harmful substances such as dioxins can be surely suppressed, and almost no ash remains.

In addition to the above, the heating element not only has a heat storage effect of the carbonaceous material and is advantageous for heat generation,
Since the outer surface of the carbonaceous material is covered with a metal, the durability can be greatly improved as compared with the case where only the carbonaceous material is used. Further, even if one heating unit fails in the middle of processing, it is possible to suppress the discharge of harmful substances by raising the temperature of at least one of the remaining heating units.

The present invention is not limited to the above embodiment, but may be as follows. That is, the first heating unit 11A, the second heating unit 11B, and the third heating unit 11C.
Although the heating cross-sections of No. 1 and No. 2 are the same in the above-mentioned embodiment, some or all of them may be different. Further, at least three heating units are required, but more heating units may be set. Further, the gas discharged from the discharge port 4 may be used to drive the generator using the gas to generate electricity without suddenly discharging the gas to the outside air.

Further, when the heating section fails, for example, when the second heating section 11B fails, in the above embodiment, only the third heating section 11C is heated, but the temperature of the first heating section 11A is also increased. The temperature may be raised, or only the first heating unit 11A may be raised in temperature. Although the cycle control unit 21 uses the inverter system in the above embodiment,
Another method may be used. Further, although air is supplied from the air duct 18 to the discharge pipe 17 to promote discharge of gas generated from the waste, it is not always necessary to supply air.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thermal decomposition apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 Pyrolysis chamber 2 Fireproof material 3 slot 4 outlets 5a-5c bottom plate 6 Insulation member 7a to 7f electrodes 8 power supplies 10 heating element 11A-11C heating part 21 Cycle control unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F27D 11/08 B09B 3/00 ZAB F term (reference) 4D004 AA46 CA24 CB04 CB32 4K045 AA04 BA10 DA04 RA01 RB02 RB04 4K063 AA01 AA12 BA13 CA02 FA04 FA05 FA25 FA29 FA53 FA72 FA78

Claims (7)

[Claims] 1. A discharge port for discharging waste, and a discharge port for discharging gas generated by thermally decomposing the waste,
A thermal decomposition chamber that covers the space between the input port and the discharge port with a heat-resistant material, can store the waste and the gas, a power source that can supply power, and at least a pair of electrodes to which power is supplied from the power source. And a heating part having a plurality of heating elements formed of a carbonaceous substance capable of discharging and energizing between the electrodes, at least three heating parts being provided, and each heating part is provided. A thermal decomposition apparatus, wherein the thermal decomposition apparatus is arranged in series in the thermal decomposition chamber in a state of being separated from the charging port toward the discharging port. 2. The thermal decomposition apparatus according to claim 1, wherein the power source is capable of periodically switching control of electric power supplied to the electrode between a high voltage and a low voltage. 3. The thermal decomposition apparatus according to claim 2, wherein the cycle is controlled to be shorter when the heating element has a lower temperature than when the heating element has a high temperature. 4. The heating unit is controlled to switch at least one of the remaining heating units to a higher temperature side than in a normal state at the time of an abnormality in which one of the heating units cannot be heated. The thermal decomposition apparatus according to any one of 1 to 3. 5. The thermal decomposition apparatus according to claim 1, wherein the heating element is formed by diffusing, permeating, or spraying a highly conductive metal on the outer surface of the carbonaceous material. 6. The thermal decomposition apparatus according to claim 5, wherein the highly conductive metal is at least one of chromium, molybdenum, aluminum, magnesium, and tungsten. 7. The thermal decomposition apparatus according to claim 1, wherein the carbon-based material is charcoal or bamboo charcoal baked at about 2000 ° C. or higher.