JP2000225384A - Method for separating heat-meltable plastic from waste, method for volume reducing treatment of waste, and apparatus for heat treatment of waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the recovery of plastics separated from waste by a method in which heat-melted plastics are dropped into water tank installed in the lower part of the lower part chamber of a heating container through a partition and solidified. SOLUTION: A partition plate 5 having a heater is installed in the inside lower part of a heating container 2, an openable/closable treatment material charging port 6 is formed at the upper end, and a generated gas discharging opening 10 is formed in the upper part, molten plastics are charged from the port 6 into the container 2, the port 6 is closed, a pump Pu is operated to actuate a neutralizing agent showering apparatus 17, and a gas hot plate 18 is ignited. Next, the pressure of the container 2 is reduced by actuating a suction blower 12, the heating of the container 2 is started by actuating a heater, after the inside temperature reached 250 deg.C, the heater is stopped, molten slag cooled naturally is dropped into water seal container 9 and solidified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to heat-meltable plastics from medical wastes containing heat-meltable plastics such as infectious plastic products and the like and general wastes containing heat-meltable plastics, which are substantially inseparable. And thermal decomposition of chlorine-containing resins such as vinyl chloride resin to remove hydrogen chloride, making hot-melt plastics solid fuels, recycling, thermal decomposition of heat-insoluble waste, incineration, landfill, etc. The present invention relates to a method for separating hot-melt plastic from waste, a method for heating and reducing the volume of waste, and an apparatus therefor, which enables efficient wastewater treatment.

[0002]

2. Description of the Related Art Waste plastics are originally desirably separated and recycled. However, infectious wastes for medical use which involve danger of separation and general wastes (garbage) in which plastics are mixed without being separated, It is extremely difficult to separate plastic from paper, fiber, and other waste components. At present, general waste is incinerated or landfilled while containing plastic. In addition, medical waste is incinerated by specialized processors. In these wastes, plastics are rapidly decomposed during incineration, and a large amount of gas is generated, which not only generates high heat and shortens the life of the furnace, but also causes problems such as black smoke, bad smell, and generation of dioxin. ing. In addition, the generation of dioxin can be suppressed by decomposing these wastes by an oxygen-free thermal decomposition method, but there is a problem that tar is generated. For this purpose, the hot-melt plastic is separated and collected from the waste, or
In order to use the combustible material as a fuel, there has been proposed a method of separating a heat-fusible plastic and a heat-insoluble component from medical waste containing the heat-fusible plastic.

[0003] For example, in Japanese Patent Application Laid-Open No. Hei 8-57442, medical waste containing a heat-meltable plastic is heated from the outside under an oxygen shield at an upper part partitioned by a lattice member or the like in a heating vessel. Into a molten, fluid state,
A method has been proposed in which the molten plastic is passed through a lattice member or the like, collected in a container provided at the bottom of the container, and separated from the plastic and the non-plastic material. In this method, the whole apparatus is cooled after the heat treatment, and the sterilized and separated solid plastic is collected. Odor components generated at the time of heating are burned by an afterburner connected to a heating container, and are discharged into the atmosphere through a filter unit.

Japanese Patent Application Laid-Open No. H10-168224 discloses a method of heating combustible general waste containing polyethylene from the outside in an oxygen-free state in the same manner as the above method to melt and separate and recover polyethylene. Waste plastic such as recovered polyethylene is heated from the outside in a heating vessel under reduced pressure and in an oxygen-free state to be thermally decomposed, and the condensable components in the produced gas are recovered as oil, and a gas other than oil (eg, hydrogen chloride) A method for rendering harmless by neutralization or the like is disclosed.
In this method, the molten polyethylene flowing down to the lower portion of the heating vessel is taken out of the take-out drain in a molten state.

[0005]

By these methods, the heat-meltable plastic in the waste and the heat-insoluble component such as paper and metal can be easily separated, and the plastic used as a hydrogen chloride generating source such as a vinyl chloride resin can be obtained. Is thermally decomposed and the plastic containing chlorine is not contained in the separated hot-melt plastic, so the separated plastic can be used for recycling or as a solid fuel.

However, these methods have the following problems. In the former method, since the heating container and the container for storing the molten plastic are installed in the same cabinet, the heating container and the plastic collection container in the cabinet are simultaneously removed to take out the separated plastic components. Requires cooling. If the waste is subsequently heated, it must be heated again, which wastes heating energy. There is also a problem that the solidified plastic component adheres to the container, and it is difficult to take out the solidified plastic from the container.
In addition, in the latter method, since the removal of the molten plastic from the heating container is performed through the pipe in a state where the plastic is melted, it is necessary to heat the pipe,
There is a problem that a large amount of labor and time are required for removing the plastic adhered to the pipe.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-mentioned problems, to facilitate the recovery of plastic separated from waste, and to use heating for recovery. Method for separating hot-melt plastic from unnecessary waste, and method for heat-treating waste capable of reducing, disinfecting (sterilizing), and deodorizing waste containing hot-melt plastic, and waste heat treatment apparatus therefor It is to provide.

[0008]

According to the present invention,
The waste containing the heat-fusible plastic is placed in the upper chamber of a heating vessel divided into upper and lower compartments by a partition, and the waste is heated in an oxygen-free or low-oxygen state, and the heat-fusible plastic in the waste is heated. When the waste is separated into hot-melt plastic and hot-non-meltable waste, the heated and melted plastic is passed through a partition formed so that the molten plastic can flow down to the lower part of the lower chamber of the heating vessel. A method for separating hot-melt plastic from waste characterized by being dropped into a water tank provided and solidified, and the above-mentioned hot non-meltable waste from which hot-melt plastic is separated is anoxic or hypoxic. And a method for reducing the volume of waste, characterized in that it is further heated and thermally decomposed, and the waste containing heat-meltable plastic is heated in an oxygen-free or low-oxygen state. The heating container is composed of a container and a water tank provided at the lower part thereof.The heating container is divided into upper and lower chambers by a partition formed so that molten plastic can flow down, and the waste is put in the upper chamber and heated in the above state. In addition, there is provided a waste heat treatment apparatus, wherein a water tank for dropping and solidifying molten plastic flowing down through the partition is provided at a lower portion of the lower chamber.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to embodiments of the present invention. In the present invention, the separation of the plastic from the waste containing the heat-meltable plastic is performed by heating the waste in a heating vessel in an oxygen-free state under an oxygen-free or low oxygen concentration to melt the heat-meltable plastic. Is separated from the waste by the same method as the above-mentioned proposed method, except that the molten plastic that separates and flows down is dropped into a water tank provided at the lower part of the heating vessel, and is cooled and solidified. It is very easy to collect plastic.

The waste to be treated by the present invention is not particularly limited as long as the waste contains plastic which is melted and fluidized by heating, and examples thereof include general waste and medical waste. Further, the kind of plastic is not limited. For example, those having crystallinity such as polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, and ethylene-vinyl acetate copolymer, and non-crystals such as polystyrene and polyvinyl chloride (vinyl chloride resin) Sex.

In the present invention, first, waste containing a hot-melt plastic (hereinafter, may be simply referred to as plastic) is put into an upper chamber of a heating vessel which is divided into upper and lower chambers by a partition. The plastic is melted and fluidized by heating under oxygen or low oxygen concentration. The heating temperature for melting and fluidizing the plastic varies depending on the type of the plastic.
The range of -300 ° C is preferred. The molten plastic flows down the waste by gravity and spontaneously separates from the other heat-insoluble waste components. In order to promote the separation of the plastic and to ensure the separation, it is preferable to keep the temperature in the heating vessel in the above range during the separation of the plastic.

At this time, if oxygen is present in the heating container at a concentration that ignites paper, fiber, or the like, it is difficult to maintain the heating temperature within the above range. Furthermore, even if the above-mentioned temperature range can be maintained in a state where the oxygen concentration is high, since this also creates conditions for generating dioxin, the oxygen concentration in the heating vessel is high in this sense. It is not preferable. The low oxygen concentration in the present invention means that oxygen may be present at a concentration at which the residual waste from which the plastic is separated does not ignite.

The heating vessel is usually heated from outside the heating vessel by an electric heater or a gas burner. The plastic that has been melted and fluidized by heating falls through a partition between the upper and lower chambers that allows the plastic to flow into the lower chamber, falls into a water tank provided at the lower part of the lower chamber, and cools and solidifies. If necessary, the partition can be heated. Further, the separated plastic can be solidified into a shape that can be easily handled by cutting the plastic flow flowing down through the partition into an appropriate size using a rotary cutter or the like. The partition is not particularly limited as long as the molten and fluidized plastic is formed so as to be able to pass through, and examples thereof include a partition plate having a suitable opening, a grate, and a wire mesh.

At the above-mentioned heating temperature, the vinyl chloride resin often contained in the waste is decomposed to generate hydrogen chloride. Therefore, by keeping the heating device at the above-mentioned temperature for a time suitable for separating the heat-meltable plastic in the waste from inorganic materials such as paper and metal and heat-insoluble waste components such as fibrous materials, during this time, the chloride is removed. The vinyl resin is dehydrogenated and further decomposed, and the chlorine content in the plastic separated by melting and flowing is reduced, which is convenient for recycling or discarding the separated plastic.
If there is a possibility that the waste contains a vinyl chloride resin or another substance that generates an acidic gas, it is necessary to capture an acidic gas such as a hydrogen chloride gas by an appropriate method.

The separated hot-melt plastic is taken out of the tank by a suitable means such as a belt conveyor from a water tank, and is recycled or disposed of, thermally decomposed under oxygen cutoff, incinerated in a plastic incinerator, etc. Can be attached to On the other hand, the volume of the heat-treated waste is reduced by removing the plastic therein. To further reduce the volume, the residual waste can be pyrolyzed in an oxygen-free or low oxygen concentration atmosphere following separation of the hot melt plastic. Alternatively, it may be burned under an oxygen supply or subjected to other treatment such as landfill.

In the case where the remaining waste is thermally decomposed under the cutoff of oxygen, the waste is usually heated to 400 to 600 ° C. to thermally decompose the waste. As a result of the pyrolysis, the waste is recovered as char. If the remaining waste is to be burned in the presence of oxygen, heat and burn until ignition,
Alternatively, the waste is directly ignited and burned. In addition to the above-described acid gas, the generated gas may be a source of odor, in addition to the above-mentioned acidic gas, in the case of performing heat treatment to separate the plastic from the waste, as well as in the case of thermally decomposing the waste after separating the plastic. Since an organic substance is contained in an amount, it is necessary to capture or thermally decompose the organic substance in the generated gas before releasing it to the atmosphere.

The apparatus used for the heat treatment of the waste containing the hot-melt plastic includes the waste to be treated,
It comprises a heating vessel for heating, a means for heating the vessel, and a water tank for dropping the molten plastic. The heating vessel can block oxygen (air) when heating the waste to melt and fluidize the hot-melt plastic in the waste. In order to flow down the waste by gravity and to be separated from the waste, it is divided into two upper and lower chambers by a partition through which the molten plastic can pass. Molten plastic flows through the partition and flows down into the lower chamber.

If the waste contains a large amount of water such as a large amount of blood or body fluid, for example,
In the case of a cylindrical heating vessel, the waste is placed on a liquid evaporation vessel of suitable height having a bottom rotatably mounted around its diametric axis and heated to near 100 ° C. to remove moisture. After evaporating, the container is rotated to drop the waste onto the partition plate, and then the plastic is heated and melted, or the partition plate is formed by an appropriate means, for example, by opening and closing the opening, and a large amount is formed. If waste containing water is charged into the heating container, the openings may be closed to prevent moisture from passing through the partition, these liquids may first evaporate, and then the opening of the partition may be opened to heat and melt the plastic. it can. The means for evaporating water is not limited to these examples.

The partition may have any structure that allows the plastic fluidized by melting to flow down to the lower chamber. For example, a partition plate having a large number of holes, a wire mesh partition having an appropriate mesh size, etc. Examples thereof include a plate, a grate-like partition bar having an appropriate interval, and the like, but are not limited to these examples. Below the partition, cutting means such as a rotary cutter for cutting the flowing plastic stream to an appropriate length can be provided. In addition, a heating means such as an electric heater can be provided in the partition to promote the flow of the plastic.

The shape of the heating vessel is not particularly limited. For example, the lower chamber is formed in a conical shape or a quadrangular pyramid which facilitates collection of fluidized plastic at the bottom, and the upper chamber is formed in a cylindrical shape or a square cylindrical shape. No. The composition ratio of the upper and lower two chambers is not particularly limited, and it may be configured so that the flow and separation of the molten plastic are performed smoothly. The heating means of the heating vessel is not particularly limited as long as the vessel can be heated from the outside, and examples thereof include a burner using city gas, propane gas, an electric heater, an electromagnetic induction heating device, and the like. .

The water tank for dropping the molten plastic separated from the waste can be either a separately prepared water tank below the lower chamber of the heating vessel or a structure in which the lower part of the heating vessel can be directly filled with water. Good. Alternatively, the lower end of the heating vessel may be formed in an open state without a bottom, and the lower end of the opening may be immersed in a water tank installed independently of the heating vessel, and the open end of the heating vessel may be sealed with water. By doing this,
Not only is it easy to collect dropped and solidified plastic, but it is also easy to inspect, clean, and replace partitions in the heating vessel, and easily adjust the water surface with condensed water when treating waste with a high water content. There are many advantages such as these, which are preferable. In this case, it is preferable that the portion of the heating container immersed in water is fixed to the other portion of the heating container with a flange or the like via a gasket having an insulating effect.

If the distance between the water surface of the water tank and the partition is too close, the partition may be cooled by the rebound water when the molten plastic falls into the water tank, and the drop of the molten plastic may be hindered. In order to avoid this, it is preferable to provide an appropriate interval, for example, an interval of 20 cm or more. If there is a possibility that plastics such as vinyl chloride resin that generate hydrogen chloride gas are contained in the waste, water in the water tank may be used to absorb hydrogen chloride in order to absorb hydrogen chloride. It is preferable to add a wetting agent.

The melting start temperature of the hard vinyl chloride resin is usually around 200 ° C. However, at a higher temperature, the viscosity increases due to the dehydrochlorination reaction, and the hard vinyl chloride resin is usually partitioned without flowing down from the partition. Remain on top. On the other hand, the soft vinyl chloride resin may be melted, flow down the partition, fall into the water tank, and settle, or may increase in viscosity and remain on the partition. In each case, hydrogen chloride gas is generated. Since plastics other than chlorinated building resins hardly decompose during melting, the amount of generated gas is small. Fall into the aquarium,
The solidified plastic floats or sinks on the water surface depending on its density. Polyethylene or polypropylene floats, but usually a small amount of vinyl chloride resin or polycarbonate resin sinks. In addition, inorganic substances such as metal and gypsum that fall into the water tank through the opening of the partition sink, and a lump of paper usually floats.

When the water tank seals the heating container with water, the plastic floating in the water tank is taken out to the external water surface during or after the heat treatment of the waste by a known mechanical method such as a water flow or a water wheel, and overflowed. It can be collected by any suitable means such as scooping, scooping or scraping. On the other hand, sediment can be collected by installing a conveyor or the like at the bottom of the water tank. After the heat treatment of the waste, the treated material from which the plastic has been separated is separated into non-combustible materials such as metal and paper, and combustible materials such as fibers when the material is dropped and dropped into a water tank.
First, the sediment is recovered by a conveyor in the same manner as described above, and then the combustible material that has floated can be recovered by a conveyor or the like after removing the water in the water tank.

In the heat treatment of the waste, as described above, when the plastic in the waste is melted, fluidized and separated, if the plastic also contains a vinyl chloride resin, Decomposes to generate hydrogen chloride gas. Further, some organic substances and the like are also generated from other waste components by heating, which causes odor. Further, when the waste from which the plastic is removed is further thermally decomposed to block oxygen, depending on the waste component, an organic substance or an acid gas serving as an odor source may be generated. Therefore, it is desirable to capture and remove acidic gases and organic substances in the generated gas before releasing the generated gas into the atmosphere.

For this purpose, a generated gas discharge port is provided at the upper part of the heat treatment apparatus of the present invention, and can be connected to the generated gas treatment apparatus by piping. Examples of the generated gas processing device include a scrubber for neutralizing and removing acidic gases such as hydrogen chloride gas, a deodorizing device for adsorbing generated organic substances, a combustion device for burning, and the like, but other devices can also be connected. is there.

For example, acidic gas such as hydrogen chloride gas is removed by neutralizing the generated gas by contacting it with a slurry of calcium carbonate fine powder, lime milk, or an aqueous alkali solution such as sodium hydroxide using a scrubber. Can be.
When the amount of the acidic gas is small, it can be removed by contacting it with an alkaline substance in a dry manner. The method for capturing the acidic gas is not limited to these methods, and other conventionally known methods for capturing an acidic gas can also be used. Further, to remove organic substances in the generated gas, for example, a method in which the generated gas treated with the above scrubber is heated or heated to a high temperature and thermally decomposed, or decomposed by passing through a catalyst layer at an appropriate temperature. ,
Examples of the method include a method of adsorbing on an adsorbent such as activated carbon, a method of cooling generated gas to condense organic substances, and the like, but other methods may be used.

In the present invention, the heat treatment is performed under reduced pressure, and the generated gas may be processed as described above, if necessary. Therefore, the generated gas discharge port can be connected to any suction means such as a blower.

By using the waste heat treatment apparatus of the present invention as described above, waste (mixed waste) containing hot-melt plastic is separated into hot-melt plastic, combustibles, and incombustibles. be able to. Since the separated hot-melt plastic is hardly decomposed except for the vinyl chloride resin, it can be recycled depending on the composition. Further, the processed material is sterilized under normal heat treatment conditions, and can be sanitized harmlessly.
In addition, when the water tank seals the heating container with water, one end of the heating container can be formed in an open structure, so that thermal distortion of the heating container due to heating can be released. Furthermore, there is no need to provide an outlet for the processed material
Since there is no need to provide an extruder or the like for removing the molten plastic, the structure of the apparatus can be significantly simplified, and the manufacturing cost can be reduced.

[0030]

Next, the present invention will be described specifically with reference to examples. Example 1 70 liters (4.0 kg) of non-combustible garbage from homes containing a large amount of hot-melt plastic was treated using a heat treatment apparatus 1 whose lower end is water-sealed as shown in FIG. The heat treatment apparatus 1 includes a heating vessel 2 and a water-sealing vessel 9 for water-sealing the lower end thereof and dropping the molten plastic. The heating vessel 2 has a diameter of 30 cm and an internal volume of 7
A cylinder of 0 liter (part above the partition plate 5 described below), the outer periphery of which is covered by an embedded heater (not shown) of 8 KW and a heating jacket 3 made of a heat insulating material installed on the peripheral surface. The heating container 2 is supported by a gantry 4. A partition plate 5 composed of a pipe with a built-in heater is provided in a lower part of the inside of the heating vessel 1, a processing material inlet 6 which can be opened and closed (sealed) is provided at an upper end, and a generated gas outlet 10 is provided at an upper part. Is provided. The lower end of the heating container is open, and a portion 7 (30 cm) of which a part is immersed in a water sealing container 9 below is fixed to the heating container 2 by a flange 8 using a heat insulating gasket. . Water sealed container 9
Is a cylindrical container having a diameter of 50 cm and an internal volume of 240 liters. Water was poured into the water-sealed container 9 until the sixth minute, and the installation height of the water-sealed container 9 was adjusted so that about 5 cm of the lower part 7 of the heating container was immersed in water.

The generated gas outlet 10 of the heating vessel is connected to the pipe 1
4, 14 'connected to the acid gas scrubber 11, the suction blower 12, and the deodorizing furnace 13. The scrubber 11 is a cylindrical container 15 having an open lower end. The open lower end is immersed in a water seal container 16 filled with an aqueous solution of a neutralizing agent (a 2% by weight suspension of calcium carbonate), and sealed. Water sealed container 16
The neutralizing agent therein is sent to a neutralizing agent shower device 17 provided above the cylindrical container 15 by a pump Pu. The generated gas treated by the scrubber 11 is sucked by a suction blower (suction capacity at normal pressure: 0.5 m ³ / min) 12, sent to a deodorizing furnace 13, and burned in a gas furnace 18.

The treated material is charged into the heating vessel 2 through the charging port 6, the charging port 6 is closed, the pump Pu is operated, the neutralizer shower device 17 is operated, and the gas furnace 18 is ignited. Next, the suction blower 12 is operated, the inside of the heating container 2 is evacuated to 10 cm in water, and the heater is operated to start heating the heating container. After 35 minutes, the internal temperature is 250 ° C
, The temperature was maintained for one hour, and the operation of the heater was stopped. After naturally cooling for one hour, the processing results were confirmed. As a result, 2 kg of small plastic lumps were dropped and floated in the water-seal container 9, and metal fragments were 0.1 kg in the case of sinking.
3 kg, while 1.5 kg of paper and glass bottles remained on the partition plate 5, and a total of 3.8 kg was collected. A very small amount of plastic adhered to the surface of the partition plate, paper or glass bottle and remained, and almost all of the plastic fell into the water-sealed container. The volume of the recovered material is about 5 liters, and the volume reduction rate by heat treatment is 9
3%.

[0033]

According to the present invention described above, it is easy to recover the plastic separated from the waste containing the plastic, and the heating of the waste achieves volume reduction, weight reduction, disinfection and odorlessness of the waste. A processing method and a heat treatment apparatus are provided.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a heating device of the present invention.

[Explanation of symbols]

 1: Heating vessel treatment device 2: Heating container 3: Heating jacket 4: Heating treatment device support gantry 5: Partition bar in upper and lower chambers 6: Waste inlet 7: Submerged part of heating vessel 8: Flange part 9: Water Sealed container 10: Outlet of generated gas 11: Scrubber 12: Suction blower 13: Deodorizing furnace 14, 14 ': Piping 15: Cylindrical container 16: Water sealed container 17: Neutralizer shower device 18: Gas stove T: Thermometer P: Pressure gauge Pu: Pump

Continued on the front page F term (reference) 4D004 AA07 AA46 AA48 BA03 CA24 CA26 CA29 CA32 CA48 CB03 CB31 CB43 DA02 DA06 4F301 AC17 BA01 BA02 BA21 BA29 BE35 BF10 BF15 BF31

Claims (6)

[Claims] 1. A waste containing a hot-melt plastic,
The waste is put into the upper chamber of the heating vessel divided into upper and lower compartments, and the waste is heated in an oxygen-free or low-oxygen state, and the heat-meltable plastic in the waste is melted to melt the waste. Upon separation into conductive plastic and heat-infusible waste, the heated and melted plastic is dropped into a water tank provided at the bottom of the lower chamber of the heating vessel through a partition formed so that the molten plastic can flow down, and solidified. A method for separating hot melt plastic from waste. 2. A method for reducing the volume of a waste material, wherein the heat-insoluble waste material from which the heat-fusible plastic has been separated is further decomposed by further heating in an oxygen-free or low-oxygen state. 3. The waste volume reduction method according to claim 2, wherein the generated gas is absorbed and / or decomposed. 4. A heating vessel for heating waste containing a hot-melt plastic in an oxygen-free or low-oxygen state and a water tank provided below the heating vessel, wherein the heating vessel is formed so that the molten plastic can flow down. A water tank that is divided into upper and lower compartments by the divided compartment, puts the waste into the upper compartment, heats in the above state, and drops and solidifies the molten plastic flowing down through the compartment is installed at the lower part of the lower compartment. Waste heat treatment apparatus characterized by the above-mentioned. 5. The waste heat treatment apparatus according to claim 4, wherein the water tank is formed so as to seal the lower part of the heating vessel with water. 6. The waste heat treatment device according to claim 4, wherein the waste heat treatment device is connected to a device that absorbs and / or decomposes generated gas.