JP2002326076A - Method for treating waste and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating waste by which waste, particularly organic material-base waste such as garbage or sludge is treated without increasing treatment cost while suppressing the generation of organic halogenated compounds and carbonized materials effectively utilizable as resources are effectively fixed and to provide equipment therefor. SOLUTION: In the method for treating waste while suppressing the generation of organic halogenated compounds, organic waste is supplied to a circulation zone which has a concentration of oxygen limited to <=5% and is heated from the outside, the interior of the circulation zone is kept at 300-800 deg.C and gas resulting from thermal decomposition and carbonized materials both generated from the waste are separately drawn from the terminal side of the circulation zone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating organic waste such as garbage and sludge, in which the generation of organic halogenated compounds is suppressed.

[0002]

2. Description of the Related Art Waste mainly composed of organic compounds such as refuse and sludge contains halogenated compounds.
When incinerated in a usual manner using air as a fuel, toxic organic halogenated compounds such as dioxins are generated. Conventionally, in order to suppress the generation of the toxic compound, attempts have been made to control the combustion conditions in a complicated manner, to add a generation suppressing substance, and to install a detoxification facility. In particular, organic halogenated compounds such as dioxins have a combustion temperature of 300 to 850 ° C.
Since it is easy to generate in the vicinity of a moderate temperature range, a method of avoiding this temperature, for example, a method of high-temperature combustion is used.

However, in these conventional methods, it is difficult to burn the whole under ideal conditions more than directly burning the waste in a non-uniform form. There was a problem with an increase in processing costs, such as a tough incinerator.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and does not increase the processing cost and suppresses the production of organic halogenated compounds, particularly wastes, sludge, etc. It is an object of the present invention to provide a method and an apparatus for treating waste mainly composed of organic substances and effectively fixing carbides which can be effectively used as resources at the same time.

[0005]

To achieve the above object, the present invention relates to a method for treating waste in which the production of organic halogenated compounds is suppressed.
% And supplied to an externally heated distribution system zone which is limited to not more than 3%, the temperature in the distribution system zone is maintained at 300 to 800 ° C., and pyrolysis gas and carbide generated from the waste are discharged from the end of the distribution system zone. It is characterized by extracting while separating more.

The present invention starts with a departure from the concept of burning as in the prior art. In order to do this, the reaction should be dominated by thermal decomposition, which is based on the breaking of chemical bonds that occurs under mild conditions, rather than oxidative combustion with exothermicity, by limiting oxygen. The zone in which the reaction is performed should always be a flow system zone that enables the supply of the raw material system and the removal of the production system, and is necessary for thermal decomposition, which is an endothermic reaction that is the main component. Heat had to be supplied externally.

Although a small amount of oxygen of 5% or less is involved in the oxidation reaction, the oxidation under such low oxygen partial pressure conditions does not go to combustion, but contributes to the heat supply from the inside by the exothermic reaction. However, local high temperature conditions are not very apparent and do not lead to the production of the toxic organic halogenated substances. Also, organic halogenated substances such as dioxins are hardly decomposable once formed,
Also, from the viewpoint of increasing the yield of carbides, limiting the entire temperature to 300 to 800 ° C. is an important factor at the same time.

In the method for treating waste according to the present invention, at least one compound selected from the group consisting of water vapor and metal carbonates, oxides, sulfates and hydroxides, together with the organic waste. Is supplied.

The addition of water vapor suppresses a violent oxidation reaction by lowering the oxygen partial pressure of the system, and furthermore, water reacts with carbon in the system to generate carbon monoxide and hydrogen, thereby reducing It becomes a gas atmosphere, suppresses generation of toxic organic halogenated compounds, and contributes to fixation of carbon in the raw material.

Also, metal carbonates, oxides, silicates,
It was found that sulfates and hydroxides have a catalytic action to promote the cleavage of the carbon chain and an action to fix free halogens in the reaction system as inorganic substances (metal salts). It is effective to make it. Examples of these compounds include sodium carbonate, iron oxide, calcium hydroxide,
And so on.

Further, in the method for treating waste according to the present invention, the pyrolysis gas extracted from the heating and flowing system zone may be 850 to 11
It is characterized by high temperature combustion at 00 ° C. Since this pyrolysis gas still has a halogen source, and contains a causative substance that potentially forms the toxic organic halogenated compound, it does not generate these compounds, and even if it did. It burns in the high temperature range where it decomposes. As a result, the halogen contained in the system becomes hydrogen halide, so that it can be easily and inexpensively removed by neutralizing with an alkaline substance in the exhaust path. The obtained high-temperature exhaust gas can be effectively used as a heat source for heating the circulation zone from the outside.

Further, the method for treating waste according to the present invention is characterized in that a carbide mainly composed of carbon extracted from the heating and flowing system zone is rapidly cooled to 250 ° C. or less and extracted. This is a means for preventing any residual halogenated substance which has migrated to the solid phase by the thermal decomposition from being converted into a toxic halogenated compound such as dioxin. This operation of the present invention is necessary so as not to come in contact with oxygen in the extracted air at a high temperature.

The present invention relates to a waste treatment apparatus in which the generation of an organic halogenated compound is suppressed, comprising a means for supplying an organic waste, a stirring means and an external heating means, and a flow restricting the oxygen concentration. System zone, and a means for separating and extracting pyrolysis gas and carbide at the end side of the flow system zone, supplying organic waste to the heating flow system zone, and maintaining the temperature within a set temperature range, thereby disposing the waste. It is characterized in that the pyrolysis gas and carbide generated from the material can be extracted while being separated from the end side of the flow system zone.

The organic waste supply means has a structure in which the space between the flow system zone and the outside air is kept well-sealed from the viewpoint of the present invention, and it is preferable that the supply rate can be freely adjusted. . Since the form of the raw material system is various, it is preferable to include means such as crushing and pulverization. Therefore, as a combination of these preferred embodiments, there is a screw feeder or the like connected to the entrance of the flow system zone.

The flow system zone is a defined, constant volume reaction zone having an inlet for supplying raw materials and an outlet for extracting pyrolysis gas and carbide, which is connected to the supply means. And external heating means. The stirrer may be a type in which the remaining material is stirred by the reaction zone itself swinging or rotating, or the remaining material may be stirred by a stirrer or the like. Further, the external heating means means to supply heat from the outside, and may be, for example, a jacket surrounding the circulation system zone connected to a high-temperature gas source, or the jacket connected to a high-temperature gas source. It may be a tube arranged in a coil shape inside the flow system zone.

The separation / extraction means is, for example, a cracked gas discharge pipe and a carbide discharge port connected to a solid-gas separation port provided near the outlet on the end of the flow system zone. A screw conveyor for discharge may be attached to the carbide discharge port.

Further, the waste treatment apparatus of the present invention is further characterized by further comprising a high-temperature combustion furnace capable of burning the pyrolysis gas extracted from the heating and circulation system zone at a high temperature. The high-temperature combustion furnace includes, for example, a burner connected to a pipe for introducing a pyrolysis gas extracted from the heating and circulation system zone and a pipe for feeding air or oxygen-enriched air to burn the pyrolysis gas at a high temperature. It is a combustion furnace having an outlet for discharging exhaust gas. For example, depending on the application of high-temperature flue gas, or for the purpose of preventing burner blockage,
It is also possible to provide a dust remover in the path at the entrance of the combustion furnace to remove solid particles accompanying the decomposition gas before supplying the gas to the high-temperature combustion furnace.

Further, the waste treatment apparatus of the present invention is characterized by further comprising carbide quenching means capable of quenching and extracting the carbide extracted from the heating / circulating system zone. The quenching means may be constituted, for example, by a heat exchanger provided in the carbide extraction path, so that the carbide being extracted is brought into contact with the heat transfer surface of the heat exchanger and cooled. The other surface of the heat transfer surface is cooled by a low-temperature medium such as water to remove heat.

From the viewpoint of cooling efficiency, the heat transfer area of the heat exchanger is preferably large in a limited space. Therefore, for example, it is possible to increase the diameter of the conduit to provide a cooling jacket surrounding the outside thereof, a multi-tubular heat exchanger inserted into the passage, a finned tube, or the like.

Further, the waste treatment apparatus of the present invention is characterized in that the heating and circulation system zone is an externally heated kiln.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be illustratively described with reference to the drawings. However, the dimensions, shapes, materials, relative arrangements, and the like of the products described in the present embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified, but are merely illustrative examples. Absent.

FIG. 1 is a process flow chart showing an example of the present invention. In FIG. 1, the stored organic waste 10
After being crushed by a supply means 111 constituted by a crusher and a screw feeder, 1 is continuously supplied into an externally heated kiln 112 which is a heating and distribution zone. Also, about 0.3% of the waste is supplied as a catalyst simultaneously and continuously from the inlet of the crusher. Then, the high-temperature exhaust gas 104 flows through the heating jacket 113 of the externally heated kiln 112 to heat the inside. During a sufficiently low temperature during the heating, the inside of the kiln is flushed with nitrogen or water vapor to replace a part of the air inside and keep the oxygen concentration at 5% or less. The internal temperature of the external heat type kiln is controlled at 300 to 800 ° C., and the carbide is guided to the lower part of the separation and extraction means 114,
The pyrolysis gas 102 is taken out from above. Carbides are extracted from the lower part of the separation and extraction means 114 so that the kiln capacity is in a steady state in balance with the supply amount of organic waste. A heat exchanger 115 is provided below the separating and extracting means as a quenching means, and is rapidly cooled at the time of extraction.

Since the pyrolysis gas 102 contains scattered particles, after the dust is removed by the bag filter 116, the high-temperature combustion furnace 1
Burn at 17. The combustion air or oxygen-enriched air 106 in the high temperature incinerator 117 is led to the furnace 117 by another route.

A part 104 of the high-temperature exhaust gas obtained in the high-temperature combustion furnace 117 is supplied to the heating jacket 1 of the external heating kiln 112.
13, which is used for heat supply necessary for decomposition, and the gas 107 after the heat supply, which is still high in temperature and discharged from the outlet of the heating jacket 113, is combined with a part of the high-temperature gas discharged from the high-temperature combustion furnace 117 to heat the boiler. For the use gas 105.

High-temperature boiler heating gas 105 is supplied to boiler 1
The steam condensed by the condenser 120 is returned to the boiler and circulated by the steam turbine generator 119 which is used as a heat source for generating steam.

The boiler heating gas 105 exchanges heat with the boiler 122 to become exhaust gas from the boiler.
After the dust is removed at 21, it is discharged from the chimney 118.

According to the process of the present embodiment, the organic waste is treated by suppressing the generation of toxic organic halogenated compounds to obtain a carbon-based carbide which can be effectively used as a resource and to generate a heat source. Thus, the boiler can be operated and the turbine generator can be operated to effectively recover energy.
Moreover, the plant can be made compact as a device that does not particularly require special materials, and the cost is low.

[0028]

As described above, according to the present invention, waste which suppresses generation of an organic halogenated compound, particularly waste mainly composed of organic substances such as garbage and sludge, without increasing the treatment cost. And a method and apparatus for effectively fixing carbides that can be effectively used as resources at the same time.

[Brief description of the drawings]

FIG. 1 is a process flow chart showing an example of the present invention.

[Explanation of symbols]

 Reference Signs List 101 Organic waste 102 Pyrolysis gas 103 Carbide 104 High temperature exhaust gas 105 Boiler heating gas 106 Air or oxygen-enriched air 107 Gas after heat supply 111 Supply means (crusher + screw feeder) 112 Heat distribution zone (external heat) 113) Heating jacket 114 Separation / extraction means 115 Quenching means (heat exchanger) 116 Bag filter 117 High temperature combustion furnace 118 Chimney 119 Steam turbine generator 120 Duplexer 121 Bag filter 122 Boiler

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroki Honda 1-8-1, Koura, Kanazawa-ku, Yokohama-shi Mitsubishi Heavy Industries, Ltd. Yokohama Research Laboratory (72) Inventor Noriaki Senba 1-8-8 Koura, Kanazawa-ku, Yokohama-shi 1 Mitsubishi Heavy Industries, Ltd. Yokohama Research Laboratory F term (reference) 3K061 NA07 NA13 4D004 AA00 AA46 AB06 BA03 CA26 CA32 CB09 CC12 DA03 DA06 DA10 4D059 AA00 BB03 BB06 BB14 EA09 EA10 EB09 EB10

Claims (8)

[Claims] 1. A method for treating waste in which generation of an organic halogenated compound is suppressed, wherein the organic waste has an oxygen concentration of 5%.
% And supplied to an externally heated distribution system zone which is limited to not more than 3%, the temperature in the distribution system zone is maintained at 300 to 800 ° C., and pyrolysis gas and carbide generated from the waste are discharged from the end of the distribution system zone. A waste disposal method characterized by extracting while separating more. 2. The method according to claim 1, wherein at least one compound selected from the group consisting of water vapor and metal carbonates, oxides, sulfates, silicates and hydroxides is supplied together with the organic waste. Waste treatment method. 3. The method for treating waste according to claim 1, wherein the pyrolysis gas extracted from the heating circulation system zone is burned at a high temperature of 850 to 1100 ° C. 4. The waste treatment method according to claim 1, wherein the carbides extracted from the heating and circulation system zone are rapidly cooled to 250 ° C. or less and extracted. 5. A waste treatment apparatus in which generation of an organic halogenated compound is suppressed, comprising a means for supplying organic waste, a stirring means and an external heating means, and a flow system zone having a restricted oxygen concentration. Having a means for separating and extracting pyrolysis gas and carbides at the end side of the flow system zone, supplying organic waste to the heating flow system zone, and generating the organic waste from the waste by maintaining the temperature within a set temperature range. A waste pyrolysis gas and carbides separated from the end of the flow system zone while being extracted. 6. The waste treatment apparatus according to claim 5, further comprising a high-temperature combustion furnace capable of burning the pyrolysis gas extracted from the heating circulation system zone at a high temperature. 7. The waste treatment apparatus according to claim 5, further comprising a carbide quenching means capable of quenching and extracting the carbide extracted from the heating and circulation system zone. 8. The apparatus for treating waste according to claim 5, wherein the heating / circulating system zone is an external heat type kiln.