JPH06226233A - Method and equipment for reducing volume of chlorine-containing plastic waste - Google Patents

Abstract

PURPOSE:To provide a method and compact equipment for detoxicating and volume-decreasing a chlorine-containing plastic waste which is low in energy consumption. CONSTITUTION:The chlorine-containing plastic waste 2 is subjected to a low temp. dry distillation in a heating oven 4, and a generated decomposed gas is sent to a gas-cleaning chamber 6, and after being cooled by spraying a washing water and also being removed with a gaseous hydrogen chloride by being absorbed in the washing water, the gas is discharged. The oil intermixing in the washing water sprayed to the decomposed gas is removed by a filter 28 and an oil adsorbent. In this way, the furnace to burn the decomposed gas is not only eliminated but also the temp. of the decomposed gas to be cooled and removed with gaseous hydrogen chloride is relatively lowered, so the whole equipment can be composed compactly without necessitating a large cooling capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment method and apparatus for detoxifying and reducing the volume of chlorine-containing plastic waste.

[0002]

2. Description of the Related Art Conventionally, as a method for treating chlorine-containing plastic waste, a method of landfilling or incineration to reduce the volume has been mainly adopted. When landfilling plastic wastes, the plastics are not biodegraded, so the volume does not decrease in the soil, and therefore a large landfill site is required to landfill a large amount of plastic wastes. However, there is a limit to the land that can be used as landfill, and securing it is becoming difficult.

Further, since plastic wastes such as medical instruments are often attached with bacteria, if they are landfilled as they are, there is a risk that the bacteria will contaminate soil or groundwater. Therefore, in particular, in order to treat plastic waste such as medical equipment, incineration and discarding that also serves as sterilization is preferable. Also, not limited to plastic waste such as medical equipment,
As for the treatment of other plastic wastes, incineration treatment is preferable in terms of volume reduction, and the volume of the residue reduced by incineration is small, so that the landfill site can be effectively used.

[0004]

However, since chlorine-containing plastics are generally flame-retardant, the combustion temperature when incinerated is as high as about 800 ° C., and a large amount of energy is required for incineration. Moreover, since the exhaust gas from combustion is also high in temperature and a large amount is generated, the equipment for cooling the exhaust gas and the components of the apparatus becomes extremely large. In addition, there is a problem that the constituent members of the incinerator are corroded and deteriorated by the acidic gas such as hydrogen chloride gas generated at the time of combustion. If an acid resistant member is used in the incinerator, the durability is improved, but since the acid resistant fireproof heat insulating material and the like are extremely expensive, there is a problem that the incinerator is expensive.

Further, if chlorine gas such as hydrogen chloride gas in the gas generated during combustion is diffused into the atmosphere as it is, it will damage the human body and the environment. Therefore, the generated chlorine gas cannot be diffused into the atmosphere. Therefore, it is necessary to remove the chlorine-based gas from the gas generated when the plastic waste is burned. Therefore, as a method of treating chlorine-containing plastic waste, chlorine-containing plastic waste is subjected to low-temperature carbonization, the generated decomposition gas is further burned to remove hydrocarbons, and then hydrogen chloride gas is absorbed in water or slaked lime. Although a method of removing it has been proposed (see, for example, JP-A-48
No. 39572, Japanese Patent Application Laid-Open No. 3-78006), a gas incinerator is required in addition to a plastic distillation apparatus for plastic waste, which causes a problem that the plastic waste processing apparatus becomes large.

An object of the present invention is to eliminate the above-mentioned conventional problems, and it is possible to detoxify and reduce the volume of chlorine-containing plastics with low energy and to downsize the structure.
It is an object of the present invention to provide a detoxifying volume reduction method and apparatus for chlorine-containing plastics.

[0007]

The above object of the present invention is achieved by the following constitution. (1) Low temperature dry distillation of chlorine-containing plastics, cooling the generated decomposition gas by spraying washing water, absorbing hydrogen chloride gas in the decomposition gas into the cleaning water and removing it, and then discharging it into the atmosphere. A method for reducing the volume of chlorine-containing plastic waste, characterized in that cleaning water having absorbed gas is permeated through an oil capturing member to remove tar-like or liquid hydrocarbons generated by cooling the decomposition gas and mixed in the cleaning water. .

(2) A heating furnace for dry distillation of chlorine-containing plastic waste at a low temperature, and a decomposition gas cleaning chamber having cleaning water spraying means which is in communication with the heating furnace and sprays cleaning water onto decomposition gas generated by dry distillation. A circulation and discharge control means for the decomposed gas remaining in the apparatus after the completion of dry distillation, an oil capturing member through which the sprayed cleaning water permeates, and a storage means for storing the cleaning water permeating through the oil capturing member. An apparatus for reducing the volume of chlorine-containing plastic waste, comprising:

[0009]

The method of the present invention, as shown in the process flow of FIG. 1, is a low temperature dry distillation → decomposition gas cooling cleaning → discharging process for detoxifying gas and removing oil from cleaning water → neutralizing cleaning water → cleaning for discharging. Decontaminate the contaminated cleaning water generated by.
In the method and apparatus for reducing the volume of chlorine-containing plastic waste of the present invention, the decomposed gas generated by low-temperature carbonization of the chlorine-containing plastic waste is hydrogen chloride absorbed in the wash water by spraying the wash water. To be removed.
After that, the decomposed gas remaining in the apparatus after the completion of the dry distillation is cooled by being circulated between the heating furnace and the gas cleaning chamber for a predetermined time, and the hydrogen chloride gas is completely removed.
Further, this circulation promotes cooling of the heating furnace after the completion of the dry distillation. The decomposed gas is cooled by washing water and the hydrogen chloride gas is removed, and then the decomposed gas is exhausted from an exhaust portion such as a chimney.

The volume reduction treatment time for chlorine-containing plastics is
It is the time until no decomposition gas is generated from the chlorine-containing plastic waste by dry distillation and hydrogen chloride gas is removed from the generated decomposition gas by washing. It is also possible to provide a sensor for detecting hydrogen chloride gas and perform the processing based on the detection information of the hydrogen chloride gas by the sensor without particularly setting this predetermined time before the processing. Further, the treatment time may be experimentally obtained in advance from the components and the volume of the chlorine-containing plastic waste, and the treatment may be performed based on the calculated time.

Further, by cooling the decomposed gas, tar-like or liquid hydrocarbons (benzene, toluene, etc.)
May occur and these may be mixed in the wash water. Therefore, by passing the wash water through the oil trapping member, tar-like or liquid hydrocarbons are trapped by the oil trapping member and separated from the wash water. The oil capturing member may be one that physically captures hydrocarbons or one that chemically captures hydrocarbons.

After the separation of these components, the washing water is
After the pH is adjusted as necessary, it can be circulated and supplied again to the cleaning chamber and sprayed on the decomposed gas in the cleaning chamber for use. Further, by the dry distillation treatment, the residue in the heating furnace is reduced to 1/3 to 1/5 of the waste before treatment.

According to the present invention, since the step of burning the combustible substance in the cracked gas before removing the hydrogen chloride gas from the cracked gas is not included, a device using high energy such as a combustion device is unnecessary. The hydrogen chloride gas can be removed with extremely low energy, and the cleaning device also cools the decomposition gas by spraying cleaning water on the decomposition gas, so a cooling facility to suppress the dissipation of heat to the atmosphere. Is not necessary, and the volume reduction apparatus does not become large.

By cooling the decomposition gas, tar,
Even if oil components such as benzene and toluene are generated and mixed in the cleaning water, the cleaning water is removed by permeating the oil capturing member, so that the cleaning water can be reused. Further, even when the wash water is discarded, it is only necessary to adjust the pH, and the volume can be reduced with low energy as a whole.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a block diagram of an apparatus for treating chlorine-containing plastic waste, which is an embodiment of the present invention.

The treatment apparatus comprises a heating furnace 4 for low-temperature carbonization of chlorine-containing plastic waste (hereinafter simply referred to as plastic) 2, a cleaning chamber 6 for cleaning decomposition gas generated from the plastic 2 in the heating furnace 4, and decomposition gas. And a water storage tank 8 for storing cleaning water after cleaning. The heating furnace 4 is equipped with a heater 10 and is controlled so as to heat the plastic 2 contained therein at about 350 ° C to 500 ° C.
Further, the heating furnace 4 can be airtightly closed by the door 12, and the plastic 2 can be supplied without being supplied with oxygen from the outside.
Is heated (dry distillation).

In the cleaning chamber 6, a labyrinth-like passage through which cracked gas introduced from the heating furnace 4 through the duct 13 passes is formed by a partition wall, and the passage is filled with a Raschig ring 14 having a large surface area. ing. Further, the cleaning chamber 6 is provided with a nozzle 18 for ejecting alkaline cleaning water supplied from a cleaning water tank 16 described later. The cleaning water ejected from the nozzle 18 flows down along the surface of the Raschig ring 14. Therefore, the decomposed gas can come into contact with a large amount of washing water flowing down, and the hydrogen chloride gas in the decomposed gas can be easily dissolved.

Further, since the decomposed gas is cooled by spraying cleaning water in the cleaning chamber 6, it is not necessary to provide a cooling means for the decomposed gas. As described above, the wash water has two functions of absorbing hydrogen chloride and cooling decomposed gas. The decomposed gas that has passed through the cleaning chamber 6 is diffused into the atmosphere from the chimney 46 with the damper 24 opened. As a result,
The gas discharged from the chimney 46 is mainly a hydrocarbon that is a gas at room temperature such as methane contained in the air and cracked gas existing in the apparatus before the treatment. Further, when the decomposed gas is completely exhausted from the plastic 2, it becomes difficult for the decomposed gas remaining in the heating furnace 4 to flow into the cleaning chamber 6, so the damper 25 is opened and the blower 22 is operated to pass through the cleaning chamber 6. The decomposed gas is sent again into the heating furnace 4 and circulated. Then, the decomposed gas remaining in the heating furnace 4 flows into the cleaning chamber 6 together with the sent separation gas, and is cooled and cleaned. In the illustrated configuration, the duct 20 circulating from the cleaning chamber 6 to the heating furnace 4 passes below the cleaning chamber 6, so that the decomposed gas is cooled when returning to the heating furnace 4. The moving method of the decomposed gas is indicated by an arrow G.

On the other hand, the cleaning water that has absorbed hydrogen chloride gas is
It is designed to flow into the wastewater storage portion 26 and further overflow from the wastewater storage portion 26. The wash water overflowing from the dirty water storage section 26 passes through an oil capturing member composed of a filter 28 and an oil adsorbent 30 arranged under the dirty water storage section 26, and flows down, and the stored water defined under these It is housed in the tank 8.

The filter 28 mainly filters and removes tar components mixed in the wash water, and the oil adsorbent 30 absorbs and removes liquid hydrocarbons such as benzene and toluene mixed in the wash water. It is a thing. In this embodiment, the filter 28 and the oil adsorbent 30 constitute an oil trapping member in this way, but it is not always necessary to separate them in this way, and for example, an oil made of a fibrous material in a net-shaped bag body. It is also possible to use an oil trapping member filled with an adsorbent.

By passing the wash water through the filter 28 and the oil adsorbent 30, the harmful substances are completely removed from the wash water. The cleaning water ejected from the nozzle 18 in the cleaning chamber 6 is filled in the cleaning water tank 16. As for the cleaning water in the cleaning water tank 16, after introducing fresh water into the cleaning water tank 16,
It is adjusted by supplying a predetermined amount of alkaline water from the adjacent alkaline water tank 32.

The alkaline water tank 32 is formed with a charging port 34 for charging slaked lime or caustic soda, and the fresh water initially introduced into the cleaning water tank 16 can be introduced by a pump 36. Then, slaked lime or caustic soda is dissolved in fresh water to prepare alkaline water. The pH of the alkaline water is preferably about 11-12. The supply of each liquid is performed by opening and closing the valves 38, 39, 40, 41 and driving the pump 36. The moving direction of the liquid is indicated by the arrow W. The cleaning liquid stored in the water storage tank 8 after the cleaning process can be discharged by opening the valve 42. However, since this cleaning liquid can be repeatedly used to some extent, it can be returned to the cleaning water tank 16 by opening the other valve 44.

Next, a method for reducing the volume of plastic having the above structure will be described. Since it is necessary to prepare the wash water before the volume reduction treatment, the preparation of the wash water will be described first. First, the valve 38 is opened to supply water (for example, tap water) to the cleaning water tank 16. Next, the valve 41 is closed and the liquid supply to the cleaning chamber 6 is blocked, the valve 40 is opened and the pump 36 is operated to supply the cleaning water in the cleaning water tank 16 to the alkaline water tank 32. Next, alkaline water tank 3
Add slaked lime or caustic soda to 2 to obtain high pH (pH ≈ 1
2) Make alkaline water. Finally, the valve 39 is opened and alkaline water is put into the washing water tank 16. The alkali concentration of the wash water is adjusted within a certain range by adjusting the valves 38, 39 and 40.

Next, detoxification and volume reduction processing of chlorine-containing plastic waste will be described. After the adjustment of the washing water is completed, the plastic 2 is put into the heating furnace 4, the door 12 is closed, and the heater 10 heats it to start dry distillation. The door 12 has a structure that blocks the intrusion of air from the outside. Further, the damper 25 is closed simultaneously with the start of heating, the damper 24 is opened, and the valve 40
Is closed, the valve 41 is opened, and the pump 36 is operated to start spraying washing water.

When the heating temperature reaches about 250 ° C., decomposition gas such as hydrogen chloride gas starts to be generated, and the decomposition gas is sent to the cleaning chamber 6. The dry distillation temperature is preferably 350 ° C to 500 ° C. Since the decomposition reaction during dry distillation is an endothermic reaction, the temperature of the decomposition gas sent to the cleaning chamber 6 is lower than the temperature in the heating furnace 4 and is 150 ° C. or less. The decomposed gas sent to the cleaning chamber 6 is cooled by the cleaning water sprayed from the nozzle 18 in the cleaning chamber 6, and the hydrogen chloride gas in the decomposed gas is absorbed and removed by the cleaning water. The cleaning waste liquid that has absorbed hydrogen chloride gas may contain tar-like hydrocarbons generated by cooling the decomposition gas and liquid hydrocarbons such as benzene and toluene. Therefore, the cleaning waste liquid is once stored in the waste water storage unit 26, and then the filter 2
8 and the oil adsorbent 30 and separated into tar-like hydrocarbons and liquid hydrocarbons, respectively, and then stored in the water storage tank 8.

The washing water accumulated in the water storage tank 8 is washed water tank 16
The washing water is gradually acidified by absorbing hydrogen chloride in the decomposition gas and its pH is lowered. Therefore, alkaline water is appropriately mixed in the washing water tank 16 to p.
It is necessary to adjust H. For example, the washing water can be reused as it is until the pH is about 5, but it is preferable to add alkaline water to raise the pH to about 10 when the pH reaches about 7, and then reuse it. Then, while the reuse of the wash water is repeated, when the salt concentration becomes high and the usage limit is reached, the pH is adjusted to 5 to 8 and the drainage valve 42 is opened to discharge the wash water. In order to adjust the pH of the wash water before draining, it is preferable to provide an inlet (not shown) in the water storage tank 8 and to make the slaked lime or caustic soda device in the water storage tank 8 compact. Further, when the water level in the cleaning water tank 16 is lowered during the treatment, the ball valve 44 is activated and a part of the cleaning drainage collected in the water storage tank 8 is sent to the cleaning water tank 16.

The dry distillation ends when the generation of the decomposition gas ends, but since the decomposition gas remaining in the heating furnace 4 and the duct 13 is treated after the completion of the dry distillation, the damper 24 is closed after the completion of the dry distillation. The damper 25 is opened to operate the blower 22. As a result, the decomposed gas circulates in the route of the heating furnace 4 → the cleaning chamber 6 → the blower 33 → the heating furnace 4 → the cleaning chamber 6 →, and the cooling of the decomposed gas and the removal of the hydrogen chloride gas are completed. Further, this cooling also promotes cooling of the heating furnace 4. After the decomposition gas is cooled and the hydrogen chloride gas is removed, the damper 24 is opened and the detoxified gas is exhausted from the chimney 46. Although a small amount of hydrocarbon gas such as methane is detected in the gas exhausted from the chimney 46,
Almost no hydrogen chloride gas is detected.

[0028]

[Experimental example] 10 kg of vinyl chloride pipe (12 mm in thickness) as plastic waste, input amount of slaked lime 5 kg Water supply (tap water) 1000 liters / hour Power consumption 12 kw The temperature of the carbonization furnace is about 50 Controlled to reach 400 ° C in minutes, then 400 ° C
Was controlled to be maintained for about 60 minutes. The heating was stopped about 110 minutes after the treatment was started.

As a result of reducing the volume of the plastic under the above conditions, no gas was generated from the plastic 70 minutes after the start of operation. When the gas generated from plastic waste was collected without being released into the atmosphere, the total amount of gas was 18
It was 0 liter. As a result of examining the components of this gas, benzene, toluene, and chlorine-based gas were not detected. Further, for the purpose of confirmation, an attempt was made to burn the gas, but the gas did not burn, so it was found that benzene, toluene, etc. were not contained at all.

From this, it can be seen that the gas discharged from the processing apparatus contains no chlorine gas. Therefore, even if the exhaust gas is diffused into the atmosphere, there is no fear of adversely affecting the environment or the like. Further, all the residues in the dry distillation furnace were carbonized, and the amount thereof was 3.1 kg, and the volume of the waste could be reduced to about 1/3.

[0031]

According to the present invention, since cooling gas and hydrogen chloride gas are removed by spraying washing water without burning decomposition gas generated by low temperature carbonization of chlorine-containing plastic waste, heating for low temperature carbonization is performed. Not only does the furnace for combustion of cracked gas separate from the furnace not be required, but the temperature of the cracked gas for cooling and removal of hydrogen chloride gas is also relatively low, it does not require a large cooling capacity, and the entire device is compact. Can be configured.

Further, since the decomposition gas generated by the low temperature carbonization of the chlorine-containing plastic waste is not burned, the problem that the durability of the refractory heat insulating material in the furnace due to the high temperature hydrogen chloride gas is significantly improved. Further, the residue in the furnace after low-temperature carbonization of chlorine-containing plastic waste is reduced to 1/3 to 1/5 of the waste before treatment, thus reducing the cost required for landfill treatment. Further, even when the chlorine-containing plastic waste is medical waste, it is completely sterilized by the dry distillation treatment, so that the landfill treatment does not contaminate soil, groundwater, or the like.

[Brief description of drawings]

FIG. 1 is a flow chart of the method of the present invention.

FIG. 2 is a configuration diagram of a volume reduction processing apparatus that is an embodiment of the present invention.

FIG. 3 is a control graph of carbonization temperature.

[Explanation of symbols]

 G Decomposed gas flow direction W Wash water flow direction 2 Chlorine-containing plastic waste 4 Heating furnace 6 Washing room 8 Water storage tank 10 Heater 12 Doors 13, 20 Duct 14 Raschig ring 16 Washing liquid tank 18 Nozzle 22 Blower 24, 25 Damper 26 Waste water storage part 28 Filter 30 Oil Adsorbent 32 Alkaline Water Tank 34 Inlet 36 Pump 38, 39, 40, 41, 42, 44 Valve 46 Chimney

Claims (2)

[Claims] 1. A chlorine-containing plastic is dry-distilled at a low temperature, the generated decomposition gas is cooled by spraying cleaning water, and hydrogen chloride gas in the decomposition gas is absorbed by the cleaning water and removed, and then discharged into the atmosphere. Volume reduction of chlorine-containing plastic waste characterized in that cleaning water that has absorbed hydrogen chloride gas is permeated through an oil capturing member to remove tar-like or liquid hydrocarbons that have been generated by cooling the decomposition gas and that have been mixed into the cleaning water. Processing method. 2. A heating furnace for low-temperature dry distillation of chlorine-containing plastic waste, and a decomposition gas cleaning chamber having cleaning water spraying means which is in communication with the heating furnace and sprays cleaning water onto decomposition gas generated by dry distillation. A circulation and discharge control means for the decomposed gas remaining in the device after the completion of dry distillation, an oil capturing member through which the sprayed cleaning water permeates, and a storage means for storing the cleaning water permeating through the oil capturing member. A volume reduction treatment device for chlorine-containing plastic waste, which is characterized by being provided.