JP2005076007A - Method of thermally decomposing medical waste including chlorine-containing plastic and thermal decomposition apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal decomposition method which is capable of efficiently reducing the volume and the quantity and capable of efficiently sterilizing(making harmless) and is excellent in operability without contaminating the environment by treating relatively small amount of medical waste including chlorine-containing plastics not continuously but in batch-wise, and to provide a compact thermal decomposition apparatus. <P>SOLUTION: When thermally decomposing in batch-wise a medical waste including chlorine-containing plastics in a heating vessel in a non-oxygen or low oxygen state, it is characterized in that the waste fed into the heating vessel is compressed at normal temperature into 1.5-3.0 times of the bulk specific gravity of the originally fed waste by a compression apparatus installed in the heating vessel and thereafter subjected to thermal decomposition, and in that the produced thermal decomposition gas is sucked into the outside of the heating vessel and treated for neutralization and burning. A thermal decomposition apparatus therefor is also provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for thermally decomposing a relatively small amount of medical waste (including infectious waste) containing chlorine-containing plastic such as waste from a renal dialysis set and an apparatus therefor.

Among the medical waste, the kidney dialysis set waste is most difficult to treat because it contains a lot of body fluid such as blood and is highly infectious and contains a lot of vinyl chloride resin in the material. one of.
However, it has been the case that the waste from the renal dialysis set has been disposed of by incineration, despite the problem of hydrogen chloride gas and dioxin generation. Even in the incineration process, it is technically possible to neutralize the hydrogen chloride gas in the exhaust gas and raise the combustion temperature to reduce the amount of dioxin, and in practice it is now practiced in large incinerators. I came.
However, especially when infectious waste is processed in a large incinerator, there are dangers when it is transported to the incinerator or when the incinerator fails and a large amount of waste is contaminated by infectious waste. Considering the dangers, it is desirable to process on a small scale where infectious waste is generated.

  For these reasons, attempts have been made to develop a small incinerator that can neutralize hydrogen chloride gas in the exhaust gas. It has not been accepted. In addition, incinerators that operate in batches can reduce the amount of dioxin generated in a state where combustion is stable, but if the combustion becomes unstable at the start and end of operation, a large amount of dioxin is generated. There is a problem of generating.

  On the other hand, in the case of the pyrolysis method, even if it is a batch operation, if the high boiling point component of the pyrolysis exhaust gas is removed and the exhaust gas after neutralizing the acid gas is completely burned, the operation ends from the start of operation. There is an advantage that the amount of dioxin contained in the exhaust gas after complete combustion is extremely small at any point in time, and there is no problem. In addition, when treating waste containing a large amount of vinyl chloride resin, there is an advantage that the apparatus can be made small because the amount of generated exhaust gas is small when neutralizing hydrogen chloride gas in the generated pyrolysis exhaust gas.

However, the thermal decomposition method has the disadvantages that it is necessary to supply the energy required for the thermal decomposition from the outside, and the thermal decomposition rate is slower than the combustion, so that it is inferior to the combustion method in terms of cost performance. It was late.
In order to solve this drawback, a method of thermally decomposing the waste after compressing the waste has already been tried. However, these methods are based on a carbonization system using a continuous extrusion apparatus or a tunnel furnace heating system, and the apparatus becomes large (Patent Documents 1 and 2).
Also, infectious waste may contain incompressible metal products and gypsum products, so there may be considerable limitations in practical application.

  Furthermore, in the pyrolysis method, there may be a problem that a pipe (exhaust gas pipe) for discharging the pyrolysis product gas from the pyrolysis furnace is blocked. In order to prevent this, a method of heating the exhaust gas pipe is known, but although it can be expected to prevent precipitation of phthalic anhydride, which is a plasticizer-derived product of vinyl chloride resin, it can prevent tar and soot from sticking. However, it cannot be expected to have a sufficient effect.

  In addition, in order to neutralize acidic gas containing hydrogen chloride generated by thermal decomposition, water-insoluble alkali such as calcium carbonate is excessively added to the neutralization tank for neutralization, or water-soluble alkali such as caustic soda is added. In order to ensure neutralization, such as adding excessively and finely adjusting the pH of the treatment liquid again after completion of the treatment, the alkali tends to be excessively added. However, since the excess insoluble alkali suspension settles upon standing, this also causes a blockage of the piping and the like, which is a problem. Although automatic pH adjustment using caustic soda aqueous solution is also possible, since oil such as tar is mixed during neutralization, there is a risk of malfunction of the pH sensor and malfunction, making it difficult to maintain and manage the automatic pH adjustment device. is there.

JP-A-2-229588 Japanese Patent Laid-Open No. 11-218313

  The present invention has been made to solve the above problems, and the object of the present invention is to treat a relatively small amount of medical waste containing chlorine-containing plastics batch by batch rather than continuously, Moreover, it is an object of the present invention to provide an efficient and efficient thermal decomposition method for reducing the volume, reducing the weight, and sterilizing (detoxifying) without polluting the environment, and a compact thermal decomposition apparatus therefor.

As a result of various studies to achieve the above object, the present inventors have found that renal dialysis waste containing bulky chlorine-containing plastic (usually the bulk specific gravity in a waste bag is 0.09 kg / liter). Batch) without incurring the risk of operators being exposed to splashes of dangerous substances by putting them into a heating vessel and compressing them at room temperature to a certain percentage with a simple compression device in the heating vessel. It has been found that the heat treatment efficiency can be improved at the same time that the per-unit throughput can be increased. Note that it is actually difficult to compress general medical waste when heated, because the device may be damaged due to metal products, gypsum products, and the like mixed in the medical waste.
In addition, by targeting medical waste that can predict the content of chlorine-containing plastics, it is possible to predict the amount of alkali required to neutralize the acidic gas in the pyrolysis exhaust gas. I found out that The present invention has been completed based on these findings.

According to the present invention, when the medical waste containing chlorine-containing plastic is thermally decomposed batchwise in an oxygen-free or low-oxygen state in the heating container, the waste charged in the heating container is stored in the heating container. Compressed at 1.5 to 3.0 times the bulk specific gravity at the beginning of charging with a compression device installed in the chamber and then pyrolyzed, and the pyrolysis product gas is sucked out of the heating container to neutralize and burn it. A method for thermally decomposing medical waste containing a chlorine-containing plastic is provided.
In addition, according to the present invention, medical waste containing chlorine-containing plastic can be thermally decomposed in an oxygen-free or low-oxygen state, the waste can be thermally decomposed by external heating, and the waste that can be opened and closed An apparatus comprising: a heating container having a charging port and a pyrolysis product gas discharge port; and a pyrolysis product gas processing device connected by the discharge port of the heating container and a gas discharge pipe. A medical device including a chlorine-containing plastic, characterized in that a compression device capable of compressing an object at room temperature is provided, and the pyrolysis product gas treatment device comprises the gas cleaning device and the pyrolysis product gas combustion device An object pyrolysis apparatus is provided.

  According to the present invention, medical waste containing a chlorine-containing plastic that is extremely low in volume, volume, and sterilization (detoxification), is efficient, and has excellent operability. A thermal decomposition method and a thermal decomposition apparatus are provided.

In order to reduce the amount of dioxins generated as much as possible by processing a small amount of waste containing chlorine-containing plastics such as vinyl chloride resin, such as renal dialysis waste, thermal decomposition is not performed by incineration but by thermal decomposition. Thereafter, it is effective to neutralize the generated acidic exhaust gas and completely burn the exhaust gas after neutralization.
Such a thermal decomposition method is already known, for example, from JP-A-11-270822. Many of the known thermal decomposition methods employ a reduced pressure pyrolysis method, but this causes neutralization of the generated acidic exhaust gas and pressure loss occurs in the exhaust gas treatment device for condensing and removing the high boiling point components. If not sucked with a vacuum pump, etc., there is a risk that the heating vessel (hereinafter sometimes referred to as a pyrolysis furnace) will be pressurized and the untreated pyrolysis exhaust gas will leak out. It is done in. For example, if it is a small apparatus and a thermal decomposition furnace or a neutralization apparatus can be easily sealed, decompression is not an essential condition.

The thermal decomposition treatment of the medical waste containing the chlorine-containing plastic according to the present invention uses the known thermal decomposition method as described above, and the medical waste is compressed in the thermal decomposition furnace. It is characterized in that it is thermally decomposed after being compressed to a predetermined ratio by an apparatus.
The medical waste is 1.5 to 3.0 times, preferably 1.5 to 2.5 times the bulk specific gravity at the beginning of the pyrolysis furnace, in order to increase the treatment capacity and pyrolysis efficiency of the pyrolysis furnace. It is preferable to compress at room temperature so that the bulk specific gravity is more preferably 1.5 to 2.0 times. By compressing in this way and filling up to approximately 90% of the volume of the pyrolysis furnace and carrying out pyrolysis, the processing capacity can be significantly improved. Thermal decomposition is a batch type.

Thermal decomposition is performed by heating the medical waste to, for example, 250 to 550 ° C. in an oxygen-free state or a low-oxygen state (a concentration at which the chlorine-containing plastic is not thermally decomposed to produce dioxins). The pyrolysis product gas is discharged from the pyrolysis furnace, the acidic gas (hydrogen chloride) in the exhaust gas is removed by washing and neutralization, and the tar content of the high boiling point component is condensed and removed. The exhaust gas after these components are removed is subjected to combustion treatment.
Although medical waste containing chlorine-containing plastics is reduced in volume at the same time as detoxification (sterilization) by such thermal decomposition, a problematic amount of dioxin is not generated.

  In the present invention, the medical waste containing chlorine-containing plastic to be thermally decomposed is limited to a specific medical waste such as renal dialysis-related waste, so that the content of chlorine-containing plastic in the waste is reduced. As a result, the amount of acid gas generated by thermal decomposition of the waste can be predicted, and therefore the amount of alkali used in the neutralization tank can also be predicted. Therefore, when thermally decomposing a certain amount of medical waste, the amount of alkali required for neutralizing the amount of acid required for each batch is neutralized by adding in advance to the neutralization tank. There is no need to use an alkali excessively, there is no need to sequentially measure the pH of the neutralization layer, and there is no need to adjust the pH with an alkali, and there is an advantage that the neutralization operation becomes extremely easy.

  The pyrolysis furnace used for the pyrolysis of the present invention needs to be provided with an inlet that can be opened and sealed and an outlet for the pyrolysis product gas. Pyrolysis furnaces and pipes (pyrolysis product gas (exhaust gas) discharge pipes) are in contact with acid gas at high temperatures of up to around 500 ° C and treat exhaust gas, so they have a certain level of heat resistance and corrosion resistance. is necessary. For example, the material may be stainless steel or the like, but the material is not particularly limited as long as the above requirements are satisfied.

  Pyrolysis is usually performed by heating from outside with the pyrolysis furnace sealed except for the discharge port, but it is also possible to heat by heating an inert gas such as heated nitrogen into the furnace. The point is to keep the inside of the pyrolysis furnace in a low oxygen or oxygen-free state during heating in order to prevent the generation of dioxins.

Exhaust gas generated by thermal decomposition of waste containing chlorinated plastic usually contains acidic substances such as hydrogen chloride, organic compounds such as oil such as tar, soot, etc. in addition to water vapor. Yes.
Tar and soot in the exhaust gas may gradually accumulate in the exhaust pipe of the pyrolysis furnace, leading to a serious increase in the pressure of the pyrolysis furnace or clogging the exhaust pipe. The present inventors estimated the dirt in the discharge pipe from the degree of decompression of the pyrolysis furnace for each batch processing, and dismantled the discharge pipe and started cleaning before the start of operation. As a result of diligently providing the device, it was confirmed that dirt in the discharge pipe could be removed without taking time and accumulation of dirt could be prevented. The scraping device is not particularly limited as long as the tar attached and accumulated in the discharge pipe can be easily scraped off. For example, the inner diameter of the discharge pipe is attached to the tip of a rod-shaped handle that can be moved back and forth in the discharge pipe. A scraping rod to which a belt-like ring having a smaller diameter is attached may be mentioned.

  On the other hand, a problem in neutralizing and removing acidic substances (gas) is knowing how neutralization is completed. This problem can be avoided by bringing a water phase in which a water-insoluble alkaline substance such as calcium carbonate is suspended in a neutralization equivalent or more into contact with an exhaust gas containing acidic gas to neutralize it. This creates a new problem of settling.

  In addition, when using a water-soluble alkali such as caustic soda, there is no problem that the alkali settles, but it is difficult to accurately add a neutralization equivalent of alkali. If the pH of the aqueous phase is deviated from the neutralization point after completion of pyrolysis (if it is on the acidic side), correct by adding alkali, or monitor the pH of the neutralization tank during the pyrolysis process. However, it is necessary to sequentially add alkali. At this time, maintenance of the pH meter is also necessary.

  When treating the kidney dialysis set waste as a specific medical waste, for example, the inventors of the present invention have the size (capacity) of the waste bag when collecting the kidney dialysis set waste from the medical site. It is possible to experiment by considering that it is possible to add caustic soda in an amount corresponding to the neutralization equivalent of generated hydrogen chloride, etc. by specifying the weight and the number of bags into the pyrolysis furnace The present invention was confirmed. In this method, there is no need for time-consuming management of the pH meter and fine adjustment of the pH.

  Pyrolysis exhaust gas from which acidic substances have been removed contains organic substances and soot from low to high boiling points, but the exhaust gas is stable even when the amount of combustible gas in the pyrolysis exhaust gas is small. It can be deodorized and removed by directly sending it to a pyrolysis gas combustion furnace (deodorization furnace) equipped with a heating heat source so that it can be combusted and completely burning it into carbon dioxide gas and water vapor.

Oils consisting of high-boiling components and soot that have migrated to the aqueous phase in the neutralization process of exhaust gas containing acidic substances can be treated as liquid waste after oil-water separation, or solidified using the waste heat of the equipment and reduced in weight. It is also possible to do.
In the case where the thermal decomposition is performed in a reduced pressure state, it is possible to simplify the apparatus by sealing a part of the apparatus, for example, a cleaning apparatus (cleaning tower).

The deodorizing furnace used in the present invention includes a heating heat source having a calorific value that sufficiently enables high-temperature combustion of exhaust gas at a stage where the content of combustible gas components discharged at the beginning of thermal decomposition is small. preferable.
If the combustible gas component in the exhaust gas cannot be burned completely at a high temperature, the exhaust gas from the deodorizing furnace may have odor and the dioxin content may be high. On the other hand, if the amount of heat generated is too large for the volume of the deodorizing furnace, a flame may be generated from the opening of the deodorizing furnace.
A heat source that can be used as a heating heat source is a heat source or electric heat obtained by combustion of liquid fuel such as heavy oil or kerosene, or gaseous fuel such as city gas, propane gas, or natural gas. It is also possible to use a pyrolysis catalyst.

Next, the thermal decomposition apparatus of this invention is demonstrated with reference to drawings.
As shown in FIG. 1, an example of the pyrolysis apparatus of the present invention is a heating container (pyrolysis furnace) for thermally decomposing medical waste containing chlorine-containing plastic, and a pyrolysis product gas (exhaust gas) discharged therefrom. ). The treatment apparatus neutralizes the acid gas contained in the exhaust gas and condenses the high boiling point component (tar content), and the exhaust gas cleaning device (consisting of a cleaning tower and a neutralization tank) and the acid gas and the high boiling point component It is comprised from the exhaust gas combustion apparatus (deodorization furnace) which deodorizes by burning the exhaust gas containing the low boiling-point gas component (it becomes an odor source) after removing.

  The heating container (pyrolysis furnace) is a metal or ceramic container provided with an opening that can be opened and sealed at the upper part of the side surface, and has a discharge port for discharging exhaust gas at the upper part. The exhaust port is an exhaust gas pipe that exhausts the pyrolysis product gas and introduces it into the exhaust gas processing apparatus, and is connected to the cleaning tower of the processing apparatus. Although the shape of a heating container is not specifically limited, For example, a cross section is a circle or a rectangle. Since the external heating is common, the heating container is formed to be externally heated. The heat source is as described above.

The present invention is characterized in that a simple compressor is provided in the pyrolysis furnace for compressing the waste charged from the charging port, and the waste is compressed to a predetermined compression rate, Fill with waste to approximately 90% of volume and pyrolyze. A known compressor can be used as the compressor and is not particularly limited.
The waste usually put in a polyethylene bag is put in from the inlet of the heating container. In a state where the charged waste almost fills the heating container, the heating container is started to be heated after the charging port is sealed and compressed. At this time, when removing the acidic substance by washing the exhaust gas by wet, in order to reduce the oxygen concentration inside the heating container as much as possible at the start of thermal decomposition and to prevent the exhaust gas from leaking from the inlet, etc. It is preferable to make the inside into a reduced pressure of about minus 20 to 200 mm with a water column. Excessive pressure reduction is not preferable because it causes deformation of the apparatus and air leakage.

  As the heating method, electric heat, gaseous or liquid fuel can be used as a heat source, and heating is preferably performed so that the temperature in the pyrolysis furnace is 250 to 550 ° C, more preferably 300 to 500 ° C. is there. If it is less than 250 ° C., thermal decomposition is insufficient, and if it exceeds 550 ° C., the amount of pyrolysis gas generated increases, making it difficult to operate the pyrolysis apparatus.

  Pyrolysis gas generated by heating is sucked by a blower (BL) and enters an exhaust gas cleaning device through an exhaust gas pipe. If the exhaust gas contains an acid gas such as hydrogen chloride gas, it is possible to wash the exhaust gas with water and neutralize the acid substance dissolved in the water by contacting it later with an alkaline substance. It is more preferable to neutralize by bringing a predetermined amount of an alkaline substance commensurate with the amount of acid gas into contact with water in which it has been dissolved or suspended. Alkaline substances that can be used at this time are sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate and the like. In this case, the washing apparatus is composed of a washing tower and a water tank or neutralization tank for supplying water, alkaline water or alkali suspension water thereto, and the bottom of the washing tower is sealed with water from the water tank or neutralization tank. You can also. For example, when alkaline water is used, the washing water is supplied from the neutralization tank to the top of the washing tower by a pump (P). The washing method using water or alkaline water (including alkali suspension water) can be any known method such as a wet wall tower method, a shower method, or a packed tower method, and is not particularly limited.

Tars consisting of substances having a relatively high boiling point among the plastic pyrolysis components contained in the exhaust gas by water washing and soot generated during pyrolysis are also captured in a dispersed state in the tar and transferred to the aqueous phase. Tar transferred to the aqueous phase is collected in a tar receiving tank. Since tar containing a large amount of soot may settle if left untreated, it can be captured by providing a basket or the like at the weir of the tar receiving tank.
The collected tar and soot dispersed in tar can be treated separately as waste, but it is evaporated to dryness using the waste heat of the deodorization furnace, treated with the pyrolysis residue of the heating container, and evaporated components Can be significantly reduced by incineration in a deodorizing furnace.

  The exhaust gas after the acidic substance contained in the exhaust gas and the substance having a relatively high boiling point are removed by the water washing apparatus passes through the blower (BL) and is blown into the deodorizing furnace, where, for example, a burner Complete combustion by (B). The heat source is as described above.

<Example>
The case of treating 72 kg by compressing an unused renal dialysis set at room temperature using the pyrolysis apparatus shown in FIG. 1 (Example) and the case of treating 36 kg without compression (control example) were compared.
The renal dialysis set consists of approximately 450 g of dialyzer for dialysis of blood, approximately 300 g of a soft vinyl chloride resin tube and accessory (attachment), and a needle. Separate processing is performed. In the renal dialysis set that is actually discharged from the medical field, the water inside the dialyzer is replaced with blood, and the blood also adheres to the tube, but the thermal decomposability seems not to be much different from that of an unused product.

The heating container used for the treatment is a stainless steel cylindrical container having an internal volume of 400 liters, and an opening that can be opened and closed is provided at the upper part of the side surface.
To enter kidney dialysis waste, the kidney dialysis set in a plastic bag is inserted from the inlet, and when the heating container is full, the inlet door is closed once, and the compression provided at the top of the heating container The apparatus is operated, and the press plate provided inside the heating container is lowered to compress the waste. Since the press plate stops when the compressed material shows a certain resistance, the press plate is raised again. Even if the press plate is raised, the compressed waste remains as it is. The waste plastic bag is put in again and the same operation is repeated until the heating container is filled with the compressed waste. In the case of this heating container, the amount of waste charged to a full capacity by compression was 72 kg, and the bulk specific gravity at that time was 0.18 kg / liter. Further, the amount of waste charged without compression was 36 kg, and its bulk specific gravity was 0.09 kg / liter.

  In the case of waste 72kg (12 bags in a plastic bag) as an alkaline substance for neutralizing acidic substances generated by pyrolysis, the amount of hydrogen chloride calculated from the amount of vinyl chloride resin in the waste is neutralized. Since the amount of caustic soda required for this is calculated to be about 10 kg, this amount of caustic soda was added in advance to the neutralized water tank. Similarly, in the case of processing 36 kg of waste (6 bags in a plastic bag), ca. 5 kg of caustic soda was added in advance.

The heating container is heated from the outside with a propane gas burner. Prior to heating, the blower (BL) is started with the inlet closed, and the inside of the container is depressurized to minus 50 mm with a water column.
As the internal temperature of the heating container rises, water begins to evaporate, and the vinyl chloride resin decomposes from around 200 ° C. and hydrogen chloride gas begins to be generated. From around 300 ° C., thermal decomposition of various plastics started.
The heating vessel was pyrolyzed by raising the internal temperature to 500 ° C., but the time required to raise the temperature to this temperature was 2.0 hours when treating 72 kg, and the holding time until the end of pyrolysis was It was 8.0 hours. On the other hand, when processing 36 kg, it was 1.5 hours and 5.0 hours, respectively.

The exhaust gas discharged from the heating container enters the water washing device. Since sodium hydroxide equivalent to the generated hydrogen chloride is dissolved in the washing water, the hydrogen chloride in the exhaust gas is neutralized to become an aqueous solution of sodium chloride.
The water washing apparatus uses three falling water film type towers sealed in a neutralization water tank and one packed tower.
Thermal decomposition products such as oil (tar content) and soot contained in the exhaust gas are transferred to a neutralized water tank by washing, and the floating oil is collected in a tar receiving tank and sent to the oil tank by a pump. The water phase of the neutralized water tank is discharged after being sent to the oil / water separation tank after the thermal decomposition treatment of the waste and separating the oil.

The exhaust gas from which hydrogen chloride gas, oil and soot have been removed by the water washing device is blown into a deodorizing furnace through a blower. Since the air release part of the neutralized water tank used for water sealing emits odor, the gas phase in the air release part is sucked by a blower and blown into the deodorization furnace.
The deodorizing furnace was equipped with a combustion chamber made of ceramic heat insulating material and a propane gas burner as a heat source for heating, and the gas burner continued to ignite until pyrolysis was completed.
During the pyrolysis, the internal temperature of the deodorizing furnace rose to 900 ° C. when treating 72 kg and to 800 ° C. when treating 36 kg. The temperature in the deodorizing furnace at the end of the thermal decomposition was 700 ° C. when treating 72 kg and 650 ° C. when treating 36 kg. In any case, the combustion exhaust gas from the deodorization furnace was odorless, and the gas phase in the atmosphere of the neutralized water tank was treated in the deodorization furnace, so that no odor was felt around the apparatus.

Amount of power used in the thermal decomposition described above, when 72kg treatment 5 kWh, in 3.25kwh the case of 36kg process, also propane gas usage, respectively, were 8m ^3, 5 m ^3.
The results are shown in Table 1.

From the comparison per unit processing mass in Table 1, the superiority of the waste compression processing in the present invention is clear.
In either case, it is necessary to neutralize the amount of hydrogen chloride produced by pyrolysis by using a renal dialysis set that can predict the content of chlorine-containing plastic in the waste as pyrolysis waste. By adding an amount of alkali to the neutralization tank in advance, the pH of the neutralization tank is sequentially measured, and the pH at the end of thermal decomposition is in the range of 7-8 without adjusting the pH by adding alkali. Thus, the simple operability of the present invention was confirmed, in which the number of waste bags or the weight was regulated and the alkali for neutralization was quantitatively charged.
It was also confirmed that the inside of the pipe can be easily cleaned without disassembling the exhaust pipe connected to the outlet of the pyrolysis furnace.

  The present invention is useful for sterilization (detoxification) and volume reduction of a relatively small amount of medical waste containing chlorine-containing plastics at the waste generation site.

It is the schematic explaining the thermal decomposition apparatus of this invention.

Explanation of symbols

B: Burner BL: Blower Pu: Pump T: Thermometer

Claims (5)

When medical waste containing chlorine-containing plastic is thermally decomposed batchwise in an oxygen-free or low-oxygen state in a heating container, the waste put in the heating container is compressed by a compression device installed in the heating container. Chlorine-containing, characterized in that it is thermally decomposed after being compressed to 1.5 to 3.0 times the bulk specific gravity at the time of introduction at normal temperature, and subjected to neutralization and combustion treatment by sucking the pyrolysis product gas outside the heating container Thermal decomposition method for medical waste containing plastic. The method for thermal decomposition of medical waste containing chlorine-containing plastic according to claim 1, wherein the medical waste is renal dialysis waste. In order to neutralize acidic substances such as hydrogen chloride gas generated by thermally decomposing medical waste containing a certain amount of chlorine-containing plastics in an oxygen-free or low-oxygen state, an alkalinity in an amount corresponding to the amount of the acidic substances in advance A method for thermally decomposing waste containing plastic, wherein the material is neutralized by introducing it into a neutralization tank. Medical waste containing chlorine-containing plastics can be pyrolyzed in an oxygen-free or low-oxygen state. The waste can be pyrolyzed by external heating. In an apparatus composed of a heating container having an outlet and a pyrolysis product gas treatment apparatus connected to the discharge port of the heating container and a gas discharge pipe, the waste can be compressed into the heating container at room temperature. A thermal decomposition apparatus for medical waste containing chlorine-containing plastic, characterized in that a compression apparatus is provided, and the thermal decomposition product gas treatment device comprises the gas cleaning device and the thermal decomposition product gas combustion device. The thermal decomposition apparatus for medical waste containing chlorine-containing plastic according to claim 4, wherein a wall surface scraping device is installed in the gas discharge pipe.

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