JP2822296B2 - Method and apparatus for volume reduction treatment of chlorine-containing plastic waste - Google Patents

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 detoxifying chlorine-containing plastic waste and reducing its volume.

[0002]

2. Description of the Related Art Conventionally, as a method of treating chlorine-containing plastic waste, a method of reducing the volume by landfilling or incineration has been adopted. When landfilling plastic waste, since plastic is not biodegraded, the volume does not decrease in the soil, so that a large amount of landfill is required to land a large amount of plastic waste. However, there is a limit to the land that can be used as landfill, and it is becoming difficult to secure it.

[0003] In addition, bacteria are often attached to plastic wastes, such as medical instruments, so that if they are buried as they are, there is a risk that bacteria and soil and groundwater will be contaminated. Therefore, in particular, in order to treat plastic waste such as medical equipment, incineration disposal that also serves as sterilization is preferable. Also, not limited to plastic waste such as medical equipment,
For the treatment of other plastic wastes, incineration is preferable in terms of volume reduction, and since the volume of the residue reduced by incineration is small, the landfill site can be effectively used.

[0004]

However, chlorine-containing plastics generally have a high combustion temperature of about 800 ° C. because of their flame retardancy, and require a large amount of energy for incineration. Moreover, since the exhaust gas due to combustion is also high in temperature and is generated in large quantities, the equipment for cooling the exhaust gas and the equipment components becomes extremely large. Further, there is a problem that the constituent members of the incinerator are corroded and deteriorated by an acidic gas such as hydrogen chloride gas generated during combustion. The durability can be improved by using an acid-resistant member for the incinerator, but there is a problem that the incinerator becomes expensive because an acid-resistant refractory heat insulating material is extremely expensive.

[0005] Further, if chlorine-based gas such as hydrogen chloride gas in the gas generated during combustion is directly emitted into the atmosphere, it causes harm to the human body and the environment, so that the generated chlorine-based gas cannot be emitted into the atmosphere. Therefore, it is necessary to remove chlorine-based gas from gas generated when burning plastic waste. Therefore, as a method for 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 into water or slaked lime. There has been proposed a method of removing the same (see, for example,
No. 39572, JP-A-3-7806), and a gas incinerator is required in addition to a plastic waste carbonization apparatus, so that there is a problem that the plastic waste treatment apparatus becomes large.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and it is possible to detoxify chlorine-containing plastics with low energy and reduce the volume, and to reduce the size of the structure.
It is an object of the present invention to provide a method and apparatus for detoxifying and reducing the volume of chlorine-containing plastic.

[0007]

The above object according to the present invention is achieved by the following constitutions. (1) The chlorine-containing plastic is dry-distilled at a low temperature, the generated decomposition gas is cooled by spraying the cleaning water, and the hydrogen chloride gas in the decomposition gas is absorbed into the cleaning water to be removed and then discharged to the atmosphere. A method for reducing the volume of chlorine-containing plastic waste, characterized in that the washing water that has absorbed the gas is passed through an oil trapping member to remove tar-like or liquid hydrocarbons generated by cooling the cracked gas and mixed into the washing water. .

(2) A heating furnace for low-temperature carbonization of chlorine-containing plastic waste, and a decomposition gas cleaning chamber having cleaning water spraying means communicating with the heating furnace and spraying cleaning water on decomposition gas generated by carbonization. Means for controlling the circulation and discharge of the decomposition gas remaining in the apparatus after the completion of dry distillation, an oil trapping member through which the sprayed washing water passes, and a storage means for storing the washing water passing through the oil trapping member. An apparatus for reducing the volume of chlorine-containing plastic waste, comprising:

[0009]

In the method of the present invention, as shown in FIG. 1, the process of detoxifying the gas is carried out by low-temperature dry distillation → cooling of decomposed gas → discharge, and removal of oil from the wash water → cleaning of the wash water → discharge. Detoxification treatment of the contaminated washing water generated by the above.
In the method and the apparatus for reducing the volume of chlorine-containing plastic waste of the present invention, the decomposition gas generated by the low-temperature dry distillation of the chlorine-containing plastic waste contains hydrogen chloride absorbed in the cleaning water by spraying the cleaning water. Removed.
Thereafter, the decomposition 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.
In addition, the circulation promotes cooling of the heating furnace after the completion of the dry distillation. After the decomposition gas is cooled by the washing water and the hydrogen chloride gas is removed, the decomposition gas is exhausted from an exhaust unit such as a chimney.

The volume reduction processing time of chlorine-containing plastic is as follows:
This is the time until cracking gas is no longer generated from chlorine-containing plastic waste due to dry distillation and hydrogen chloride gas is removed from the generated cracking gas by washing. The predetermined time is not particularly set before the processing, and a sensor for detecting hydrogen chloride gas may be provided, and the processing may be performed based on information on detection of hydrogen chloride gas by the sensor. Further, the processing time may be experimentally obtained in advance from the components and the volume of the chlorine-containing plastic waste, and the processing may be performed based on the calculated time.

[0011] Further, by cooling the cracked gas, tar-like or liquid hydrocarbons (benzene, toluene, etc.)
And these may be mixed into the washing water. For this reason, by transmitting the washing water through the oil trapping member, tar-like or liquid hydrocarbons are trapped by the oil trapping member and separated from the washing water. The oil capturing member may be one that physically captures hydrocarbons or one that chemically captures hydrocarbons.

The washing water after these components have been separated is
After the pH is adjusted as required, it can be circulated and supplied again to the cleaning chamber, and sprayed to the decomposition gas in the cleaning chamber for use. Further, the residue in the heating furnace is reduced to 1/3 to 1/5 of the waste before the treatment by the dry distillation.

According to the present invention, since a step of burning combustibles 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 not required. 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 cooling equipment to suppress the dissipation of heat to the atmosphere It is not necessary to provide another, and the volume reduction processing device does not increase in size.

Further, by cooling the cracked gas, tar,
Even if oils such as benzene and toluene are generated and mixed into the washing water, the washing water is removed by permeating the oil trapping member, so that the washing water can be reused. Also, when the washing 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 configuration diagram of an apparatus for treating chlorine-containing plastic waste according to one embodiment of the present invention.

The processing apparatus includes a heating furnace 4 for low-temperature carbonizing a chlorine-containing plastic waste (hereinafter simply referred to as plastic) 2, a cleaning chamber 6 for cleaning decomposed gas generated from the plastic 2 in the heating furnace 4, And a water storage tank 8 for storing cleaning water after cleaning. The heating furnace 4 includes a heater 10 and is controlled so as to heat the plastic 2 contained therein at a temperature of about 350 ° C. to 500 ° C.
Further, the heating furnace 4 can be airtightly closed by a door 12, and the plastic 2 can be closed in a state where oxygen is not supplied from the outside.
Is heated (distilled).

In the cleaning chamber 6, a labyrinth-like passage through which a decomposition 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 includes a nozzle 18 for ejecting alkaline cleaning water supplied from a cleaning water tank 16 described later. The cleaning water jetted from the nozzle 18 flows down 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 the cleaning water in the cleaning chamber 6, it is not necessary to particularly provide a means for cooling the decomposed gas. As described above, the washing water has two functions of absorbing hydrogen chloride and cooling the decomposition gas. The decomposition gas that has passed through the cleaning chamber 6 is released into the atmosphere from the chimney 46 with the damper 24 opened. As a result,
What is discharged from the chimney 46 is a gas at room temperature, such as methane contained in air and cracked gas, which was present in the apparatus before the treatment. When the decomposed gas is completely exhausted from the plastic 2, the decomposed gas remaining in the heating furnace 4 is difficult to flow into the cleaning chamber 6. The cracked 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 partial gas, and is cooled and cleaned. In the illustrated configuration, since the duct 20 circulating from the cleaning chamber 6 to the heating furnace 4 passes below the cleaning chamber 6, the decomposition gas is also cooled when returning to the heating furnace 4. The method of moving the decomposition gas is indicated by arrow G.

On the other hand, the washing water that has absorbed the hydrogen chloride gas is:
It flows into the sewage reservoir 26 and overflows from the sewage reservoir 26. The washing water overflowing from the sewage reservoir 26 permeates and flows down through an oil trapping member composed of a filter 28 and an oil adsorbent 30 disposed below the sewage reservoir 26, and the water defined under the sewage reservoir 26. It is stored in the tank 8.

The filter 28 mainly removes tar components mixed in the washing water by filtration, and the oil adsorbent 30 adsorbs and removes liquid hydrocarbons such as benzene and toluene mixed in the washing water. Things. In this embodiment, the filter 28 and the oil adsorbent 30 constitute the oil catching member as described above, but it is not always necessary to divide the oil catching member. A material filled with the adsorbent may be used as an oil capturing member.

Hazardous substances are completely removed from the washing water by passing the washing water through the filter 28 and the oil adsorbent 30. The cleaning water jetted from the nozzle 18 in the cleaning chamber 6 is filled in the cleaning water tank 16. The washing water in the washing water tank 16 is obtained by introducing fresh water into the washing water tank 16,
The adjustment is performed by supplying a predetermined amount of alkaline water from the adjacent alkaline water tank 32.

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

Next, a description will be given of a plastic volume reducing method according to the above configuration. In addition, since it is necessary to produce | generate washing water before volume reduction processing, production | generation of washing water is demonstrated first. First, the valve 38 is opened to supply water (for example, tap water) to the washing water tank 16. Next, with the valve 41 closed and the liquid supply to the cleaning chamber 6 shut off, 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, the alkaline water tank 3
2 into which slaked lime or caustic soda was added, and a high pH (pH ≒ 1)
2) Make alkaline water. Finally, the valve 39 is opened and the alkaline water is introduced into the washing water tank 16. The alkali concentration of the washing water is adjusted to a certain range by adjusting the valves 38, 39, 40.

Next, the detoxification and volume reduction treatment 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 heating by the heater 10 starts the dry distillation. The door 12 has a structure in which intrusion of air from the outside is blocked. At the same time as the start of heating, the damper 25 is closed, the damper 24 is opened, and the valve 40 is opened.
Is closed, the valve 41 is opened, and the pump 36 is operated to start spraying the washing water.

When the heating temperature reaches about 250 ° C., decomposition gas including hydrogen chloride gas starts to be generated, and the decomposition gas is sent to the cleaning chamber 6. The carbonization temperature is preferably from 350 ° C to 500 ° C. Since the decomposition reaction at the time of carbonization 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 becomes 150 ° C. or less. The decomposition 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 decomposition gas is absorbed by the cleaning water and removed. The washing waste liquid that has absorbed the hydrogen chloride gas may contain tar-like hydrocarbons generated by cooling the cracked gas or liquid hydrocarbons such as benzene and toluene. For this reason, the washing waste liquid is once stored in the sewage storage section 26,
8 and the oil adsorbent 30, the tar-like hydrocarbon and the liquid hydrocarbon are separated from each other, and then accumulate in the water storage tank 8.

The washing water accumulated in the water storage tank 8 is supplied to the washing water tank 16.
The washing water is gradually acidified by absorbing the hydrogen chloride in the decomposed gas and the pH of the washing water is lowered.
H needs to be adjusted. For example, the washing water can be reused as it is until the pH is about 5, but when the pH becomes about 7, it is preferable to add alkaline water to raise the pH to about 10, and then to reuse it. Then, while the reuse of the washing water is repeated, when the salt concentration increases and the use limit is reached, the pH is adjusted to 5 to 8, and then the drain valve 42 is opened to discharge the washing water. In order to adjust the pH of the washing water before drainage, an inlet (not shown) is provided in the water tank 8, which is preferable in terms of making slaked lime and the caustic soda apparatus compact in the water tank 8. Further, when the water level in the washing water tank 16 decreases during the treatment, the ball valve 44 operates to send a part of the washing wastewater accumulated in the water tank 8 to the washing water tank 16.

[0027] The dry distillation ends when the generation of the cracked gas ends, but after the dry distillation is completed, the damper 24 is closed after the dry distillation to process the cracked gas remaining in the heating furnace 4 and the duct 13. The damper 25 is opened to operate the blower 22. Thus, 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. This cooling also promotes cooling of the heating furnace 4. After the cooling of the decomposition gas and the removal of the hydrogen chloride gas are completed, the damper 24 is opened, and the detoxified gas is exhausted from the chimney 46. A small amount of hydrocarbon gas such as methane is detected from the gas exhausted from the chimney 46,
Hydrogen chloride gas is hardly detected.

[0028]

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

As a result of reducing the volume of the plastic under the above conditions, no gas was generated from the plastic within 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. For further confirmation, combustion of gas was attempted, but no gas was burned, indicating that benzene, toluene and the like were not contained at all.

This indicates that the gas discharged from the processing apparatus does not contain any chlorine-based gas. Therefore, even if the exhaust gas is released into the atmosphere, there is no fear that the environment and the like will be adversely affected. In addition, all the residue in the carbonization furnace was carbonized, and the amount was 3.1 kg, and the capacity of the waste could be reduced to about 1/3.

[0031]

According to the present invention, since cooling and removal of hydrogen chloride gas are performed by spraying washing water without burning decomposition gas generated by low-temperature dry distillation of chlorine-containing plastic waste, heating for low-temperature dry distillation is performed. Not only is a separate furnace for cracked gas combustion unnecessary, but also the temperature of the cracked gas for cooling and removing hydrogen chloride gas is relatively low, and a large cooling capacity is not required, making the entire device 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 reduced is also greatly improved. Furthermore, 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, so that the cost required for landfill treatment is reduced, Even when the chlorine-containing plastic waste is a medical waste, it is completely sterilized by the dry distillation treatment, so that the landfill treatment does not contaminate the soil, groundwater, and the like.

[Brief description of the drawings]

FIG. 1 is a flowchart of the method of the present invention.

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

FIG. 3 is a control graph of a carbonization temperature.

[Explanation of symbols]

 G Decomposition gas flow direction W Wash water flow direction 2 Chlorine-containing plastic waste 4 Heating furnace 6 Cleaning room 8 Water storage tank 10 Heater 12 Door 13, 20 Duct 14 Raschig ring 16 Cleaning liquid tank 18 Nozzle 22 Blower 24, 25 Damper 26 Soil water storage section 28 Filter 30 Oil adsorbent 32 Alkaline water tank 34 Input port 36 Pump 38, 39, 40, 41, 42, 44 Valve 46 Chimney

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C10G 1/10 (56) References JP-A-51-111468 (JP, A) JP-A-49-17479 (JP, A JP-A-51-59775 (JP, A) JP-A-50-16778 (JP, A) JP-A-53-21278 (JP, A) JP-A-47-32077 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) B09B 3/00 B01D 53/68 B01D 53/77 C10B 53/00 C10G 1/10

Claims (2)

(57) [Claims] Claims 1. A chlorine-containing plastic is carbonized at a low temperature, the generated decomposition gas is cooled by spraying cleaning water, and the hydrogen chloride gas in the decomposition gas is absorbed into the cleaning water to be removed and then discharged to the atmosphere. Washing water that has absorbed hydrogen chloride gas is passed through an oil trapping member to remove tar-like or liquid hydrocarbons generated by cooling the cracked gas and mixed into the washing water, thereby reducing the volume of chlorine-containing plastic waste. Processing method. 2. A decomposition gas cleaning chamber having a heating furnace for low-temperature carbonization of chlorine-containing plastic waste and a cleaning water spraying means communicating with the heating furnace and spraying cleaning water on decomposition gas generated by carbonization; Means for controlling the circulation and discharge of the decomposition gas remaining in the apparatus after the completion of the distillation, an oil trapping member through which the sprayed washing water permeates, and a storage means for storing the washing water permeating through the oil trapping member. An apparatus for reducing the volume of chlorine-containing plastic waste, comprising: