JPH1076523A - Volume-reducing device for waste plastics and its operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-size and light weight volume-reducing device for waste plastics which is capable of preventing combustible gas contained in a circulating high temperature gas from going beyond a combustible concentration and preventing temperature rise of an oxidation catalyst and a temperature uncontrollable state from occurring at the time of generation of a large amount of the combustible gas without the necessity to use a gas sensor and with the advantage of saving on time required for treatment to reduce the volume of scrap plastics. SOLUTION: This volume-reducing device for scrap plastics is equipped with a temperature sensor 9, for a heating part, which detects the temperature of a high temperature gas circulating through a hot blast circulation path. In addition, an oxidation part 14 comprises a catalyst heating part for heating an exhaust gas, a catalyst upstream temperature sensor 17 for detecting the temperatures of the heated exhaust gas, and a catalyst downstream temperature sensor 18 for detecting the temperatures of the exhaust gas treated by oxidation. Further, a control part 25 is provided which controls a heating part 8 and the catalyst heating part upon detection signals from the temperature sensor 9 for the heating part, the catalyst upstream temperature sensor 17 and the catalyst downstream temperature sensor 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste plastic volume reducing apparatus for heating and softening waste plastic materials such as styrofoam generated in homes, business establishments, stores and the like to reduce the volume thereof, and a method of operating the same. .

[0002]

2. Description of the Related Art Conventionally, a large amount of waste has been discharged from homes, business establishments, stores, and the like. Due to a shortage of processing facility capacity such as incineration and landfill, and an increase in processing costs including collection, transportation, and the like. Measures are urgent. As a countermeasure, reducing the amount of waste is the fundamental solution, but the use of resources through recycling is also very effective. Above all, waste plastic materials are attracting attention as a target for recycling because the raw material is a precious energy resource such as petroleum and it does not rot even when it is landfilled.
Styrofoam, among others, is frequently used as a distribution container due to its light weight, cushioning properties, low cost, etc., and its alternative materials have not been found so far, so it should be reused for recycling. Is strongly desired. However, when the styrofoam or the like is collected and collected at one place for recycling, there is a problem that the bulky bulk increases the transportation cost, which increases the overall recycling cost. For this reason, a volume reduction processing method and a volume reduction processing device that are installed in places where waste plastic materials are generated, such as homes, business offices, and stores, to reduce the volume thereof have been proposed. This volume reducing device softens styrene foam and the like by heating to form a softened solid. The softened solid obtained by reducing the volume is collected by a trader and recycled at a recycling factory.

[0003] However, in the method of reducing the volume of styrofoam or the like by heating, it is necessary to heat the styrofoam or the like until the styrofoam or the like softens, and in some cases, melts. ,
Exhaust gas containing styrene gas vaporized by styrene foam and flammable gas such as butane gas used for foaming is generated with odor, so that it is necessary to consider safety measures during the volume reduction treatment operation.

Therefore, as an improvement of this volume reduction processing method, the following technology (Japanese Patent Laid-Open No. 7-169607) has been proposed.
Publication). This technology circulates heated air in a processing vessel, catalyzes the circulated air, heats and compresses the waste plastic material, and recovers it.It combusts combustible gases such as styrene gas and butane gas generated from the waste plastic material. That is, the concentration of the contained exhaust gas is kept within a safe range. In this volume reduction treatment device, the generation of exhaust gas containing flammable gas such as styrene gas or butane gas is reduced by heating the styrene foam or the like stepwise to the temperature at which the styrene foam or the like softens or melts. A method of reducing the concentration of combustible gas in the air has been adopted.

[0005]

However, when a newly-expanded styrene foam is heated and softened,
A large amount of flammable gas is generated compared to when old waste styrofoam is processed, and the concentration of flammable gas in the circulating air may exceed the flammable concentration. There is a problem that the temperature rises and the temperature cannot be controlled. Increasing the time of the heating and softening treatment of styrofoam or the like can solve these problems because the flammable gas is gradually oxidized, but the treatment time becomes longer and cannot be said to be an economically effective solution. There is also a method of using a gas sensor or the like to detect the concentration of flammable gas.However, since the temperature of the exhaust gas is extremely high, there are problems such as heat resistance and life of the gas sensor and the like. It was not a solution.

Accordingly, the present invention solves the above-mentioned problems by preventing the flammable gas contained in the circulating high-temperature gas from exceeding the flammable concentration, shortening the time required for the heat softening treatment, and using a gas sensor and the like. It is an object of the present invention to provide a compact and lightweight waste plastic volume reducing apparatus and a method for operating the same, which can prevent a temperature control failure state due to a rise in the temperature of an oxidation catalyst when a large amount of combustible gas is generated without using it. .

[0007]

According to the present invention, there is provided a waste plastic volume reducing apparatus according to the present invention, wherein an oxidation section has a catalyst heating section for heating exhaust gas and a catalyst upstream temperature for detecting the temperature of the heated exhaust gas. A sensor and a catalyst downstream temperature sensor for detecting the temperature of the oxidized exhaust gas are provided. When the oxidation catalyst reaches a predetermined temperature equal to or higher than the activation temperature, a heating unit is provided by a detection signal from the catalyst upstream temperature sensor or the catalyst downstream temperature sensor. And a control unit for suppressing heating by the catalyst heating unit. Furthermore, the operation method of the waste plastic volume reducing device of the present invention is characterized in that the concentration of the flammable gas contained in the flammable gas contained in the circulating high-temperature gas increases, and the temperature of the oxidized exhaust gas rises to a predetermined temperature. The heating of the catalyst heating unit is stopped.

Accordingly, the flammable gas contained in the circulating high-temperature gas is prevented from exceeding the flammable concentration, the time required for the heat softening treatment is short, and when a large amount of the flammable gas is generated without using a gas sensor or the like. An uncontrollable state due to an increase in the temperature of the oxidation catalyst can be prevented, and a compact and lightweight waste plastic volume reducing device and an operation method thereof can be provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a processing container provided with an opening / closing lid and capable of softening waste plastic material inside, and a waste container provided on the bottom side of the processing container and having started softening. A pressurizing section for pressurizing and reducing the volume of the plastic material, a hot air circulation path communicating with the processing container and circulating a high-temperature gas for softening the waste plastic material, and a hot air circulation path communicating with the hot air circulation path. An oxidizing device having a discharge path for discharging a part of the circulating high-temperature gas, a blower provided in the hot air circulating path and a heating unit for heating the gas, and an oxidizing catalyst for oxidizing exhaust gas to be discharged in the discharge path. A heating unit temperature sensor for detecting the temperature of the circulating hot gas in the hot air circulation path, and a catalyst heating unit for heating the exhaust gas and a catalyst for detecting the temperature of the heated exhaust gas in the oxidizing unit. A flow temperature sensor and a catalyst downstream temperature sensor for detecting the temperature of the oxidized exhaust gas are provided, and when the oxidation catalyst reaches a predetermined temperature equal to or higher than the activation temperature, the temperature from the catalyst upstream temperature sensor or the catalyst downstream temperature sensor is Since the waste plastic volume reducing device is provided with a control unit that suppresses heating by the heating unit and the catalyst heating unit by a detection signal, without using a gas sensor or the like, upstream and downstream of the oxidation catalyst The catalyst upstream temperature sensor and catalyst downstream temperature sensor provided can reliably detect the flammable gas in the high-temperature gas becoming flammable, and the control unit heats and oxidizes the high-temperature gas. In order to prevent the temperature of the catalyst from rising, the heating by the heating unit and the catalyst heating unit can be suppressed.

According to the second aspect of the present invention, the control unit stops heating the heating unit and the catalyst heating unit when the detection signal from the catalyst upstream temperature sensor reaches a predetermined temperature or higher.
The possibility that the flammable gas contained in the high-temperature gas becomes flammable can be detected beforehand, preventing the temperature of the oxidation catalyst from being uncontrollable due to the generation of a large amount of the flammable gas, heating the high-temperature gas and heating the oxidation catalyst. , And the operation can be safely terminated.

[0011] The invention according to claim 3 is characterized in that the control unit stops heating the heating unit and the catalyst heating unit when the detection signal from the catalyst downstream temperature sensor reaches a predetermined temperature or higher. It is possible to detect beforehand the possibility that the flammable gas contained in the high-temperature gas will have a flammable concentration, prevent the temperature of the oxidation catalyst from being uncontrollable due to the generation of a large amount of flammable gas, The operation can be safely stopped by stopping the heating.

According to a fourth aspect of the present invention, the control unit interrupts the heating of the catalyst heating unit when the detection signal from the catalyst downstream temperature sensor has reached a predetermined first temperature or higher, and thereafter, the catalyst downstream temperature sensor When the detection signal from is reduced to a predetermined second temperature or less, heating of the catalyst heating unit is restarted,
When the detection signal from the catalyst downstream temperature sensor rises to a third temperature or more that exceeds the second temperature, the heating of the heating unit is stopped. When the flammable gas concentration is not high, the catalyst heating section is turned on and off to continue the heating softening treatment because the flammable gas concentration is low, but when the temperature of the oxidized exhaust gas becomes abnormally high and the flammable gas concentration approaches the flammable concentration, In addition, it is possible to suppress the increase in the concentration of the flammable gas in the high-temperature gas by stopping the heating of the heating unit.

According to a fifth aspect of the present invention, when the concentration of the combustible gas contained in the exhaust gas partially discharged from the circulating high-temperature gas increases and the temperature of the oxidized exhaust gas increases to a predetermined temperature, Because it is an operation method of the waste plastic volume reducing device, which is characterized by stopping the heating of the catalyst heating unit,
An uncontrollable state due to a rise in the temperature of the oxidation catalyst can be prevented.

According to a sixth aspect of the present invention, the concentration of the flammable gas contained in the gas partially discharged from the circulating high-temperature gas increases, and the temperature of the oxidized exhaust gas reaches a predetermined first temperature. When the temperature rises, the heating of the catalyst heating unit is temporarily stopped, and then, when the temperature of the oxidized exhaust gas decreases to a predetermined second temperature, the heating of the catalyst heating unit is restarted. Since the operation of the waste plastic volume reduction device is characterized in that the heating of the heating section is stopped when the temperature reaches 3, the flammable gas concentration is too low when the temperature of the oxidized exhaust gas is not abnormally high, The heating unit is turned on and off to continue the heating softening process.
When the temperature of the oxidized exhaust gas becomes abnormally high and the flammable gas concentration approaches the flammable concentration, the heating of the heating unit is stopped, and the increase in the flammable gas concentration in the high-temperature gas can be suppressed.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a side sectional view of a waste plastic volume reducing apparatus according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a waste plastic volume reducing device, a processing container 2 for storing and softening a waste plastic material 28 therein, a pressurizing unit 3 for pressing and reducing the volume of the waste plastic material 28, and a processing container 2 And a hot-air circulation path 11 for circulating high-temperature gas. The temperature of the heat-resistant container 23 is 160 ° C.
The structure is such that a high-temperature gas of a certain degree does not leak out of the waste plastic material volume reducing device 1, and a suitable material is a heat-resistant plastic material such as polyamide or a stainless steel plate.

In order to install and use the waste plastic volume reducing device 1 at a store such as a supermarket, it is appropriate that the volume of the processing container 2 is about 80 to 200 liters. The reason for this is that the installation area is not so large with such a size, and the movement is easy. On the other hand, instead of increasing the collection rate of the waste plastic material 28 or increasing the number of waste plastic volume reduction devices 1 by increasing the size of the store, the time required for one volume reduction operation is shortened to increase the throughput. This is more economical. In this case, a waste container may be provided on the side of the waste plastic volume reducing device 1 so that the waste plastic material 28 is temporarily stored.

A suitable number of high-temperature gas side discharge ports 19 are provided on the side surface of the processing vessel 2, and an opening / closing lid 6 provided with an O-ring elastic body 5 is provided on the upper surface side. The opening / closing lid 6 is opened when the waste plastic material 28 is put into the processing container 2, and is closed and closed when softening and reducing the volume in the processing container 2. Further, the pressing unit 3
Is vertically movable and provided on the lower side of the processing vessel 2.
The waste plastic material 28 which has started to be softened by a high-temperature gas of about 60 ° C. is pressed between the open / close lid 6 to reduce the volume. The pressurizing section 3 includes a pressurizing actuator 4 and a piston 26 that is reciprocated by the pressurizing actuator 4 and directly pressurizes the waste plastic material 28.

The pressurizing actuator 4 is an expandable rubber balloon-shaped air bag or the like, and is inflated by air fed from an air pump 22 to push up a piston 26 to reduce the volume of the waste plastic material 28, and thereafter, a pressure regulating valve. 13 is opened to discharge the air accumulated inside and return the pressurizing section 3 to its original position. When the volume is reduced, the waste plastic material 28 does not leak outside due to the O-ring-shaped elastic body 5. At this time, the air pressure fed is 0.1 to 0.2 kg /
cm ² is sufficient, for example, the area of the piston 26 is 1
If it is 000 cm ² , a pressing force of about 100 kg can be obtained. As described above, the structure of the pressurizing unit 3 is relatively simple, and the exhaust capacity of the air pump 22 may be small.
It can be installed in stores such as supermarkets because of its light weight and low noise. Reference numeral 7 denotes a blower having a blowing capacity of about 2500 liters / minute and provided in a hot air circulating path 11 communicated with the processing vessel 2.
The hot gas is circulated through. A heating unit 8 which is an electric heater for heating the circulating gas is provided in the hot air circulation path 11.
In addition, a heating unit temperature sensor 9 is provided near the hot air discharge port 10 of the hot air circulation path 11.

Reference numeral 12 denotes a discharge path, a part of which is provided in communication with the hot air circulation path, for branching a part of the circulating high-temperature gas and discharging it as exhaust gas to the outside of the system. In this embodiment, the diameter of the discharge port 12a is selected so as to discharge about 60 liters / minute of exhaust gas into the discharge path 12. When the waste plastic material 28 is styrene foam, the exhaust gas contains several thousand ppm of a combustible gas mixed with a foaming gas such as butane, toluene, or xylene, or a styrene monomer gas vaporized during heat softening. . The flammable concentration of these flammable gases is 80,000 pp
m or more, and this exhaust gas does not burn in the processing vessel 2 in a normal heat softening treatment. Therefore, the oxidizing section 1 that oxidizes the exhaust gas discharged and performs flameless combustion in the discharge path 12.
4 are provided. The oxidizing section 14 includes a catalyst heating section 16
An oxidation catalyst 15 for accelerating the oxidation of the exhaust gas heated by the catalyst heating unit 16, a catalyst upstream temperature sensor 17 for detecting the temperature of the heated exhaust gas, and a catalyst downstream temperature sensor for detecting the temperature of the oxidized exhaust gas 18 are provided in order along the flow direction. The oxidation catalyst 15 is, for example, a platinum-containing compound supported on a mullite ceramic containing aluminum oxide, silicon oxide or the like as a main component. Exhaust gas containing combustible gas is heated by the catalyst heating unit 16 to a temperature equal to or higher than the activation temperature of the catalyst, and combustible components passing therethrough are easily oxidized and smokelessly burned. The exhaust gas that has undergone smokeless combustion is exhausted to the outside of the system through an exhaust port 21 via an exhaust passage 12. The discharge path 12 is preferably made of a material having excellent thermal conductivity so that the heat of the exhaust gas can be easily radiated.

Reference numeral 24 denotes an air suction port provided in the heat-resistant container 23, and constantly sucks air from outside during hot air circulation. The amount of the sucked air and the amount of the exhaust gas discharged from the discharge path 12 are balanced, so that the concentration of the flammable gas in the waste plastic volume reducing device 1 can be prevented from becoming too high. The control unit 25 controls the overall operation of the waste plastic volume reducing device 1, and controls the temperature of the circulating high-temperature gas, the circulating air volume, the pressure in the pressurizing unit 3, and the like. Reference numeral 28 denotes a gallery for radiating heat generated in the waste plastic volume reducing device 1 to the outside of the system.

The operation of the waste plastic volume reducing apparatus 1 configured as described above will be described below with reference to FIG. The lid 6 is opened, and the waste plastic material 28 is put into the processing container 2. Next, when the operation is started by closing and closing the opening / closing lid 6 and pressing an operation switch (not shown), the blower 7 and the catalyst heating unit 16 are energized under the control of the control unit 25. When the temperature of the exhaust gas heated by the catalyst heating section 16 rises to about 300 ° C., the catalyst upstream temperature sensor 17 detects the temperature and transmits it to the control section 25. Here, the control unit 25 energizes the heating unit 3 to start heating. At this time, when the temperature of the circulating gas rises to a predetermined temperature, the heating unit temperature sensor 9 detects this and transmits a detection signal to the control unit 25 to automatically control the temperature to the set temperature. This control temperature is in the range of approximately 100 to 160 ° C., which can be changed depending on the type of the waste plastic material 28, and a heating pattern suitable for it can be set. Further, the temperature of the exhaust gas heated by the catalyst heating section 16 is controlled so as to be finally maintained at about 500 ° C. by a detection signal from the catalyst upstream temperature sensor 17.

The high-temperature gas becomes hot air and is discharged from the hot-air discharge port 10 into the processing container 2 as shown by an arrow b, and heats and softens the waste plastic material 28 put into the processing container 2. Next, the high-temperature gas is discharged from the side discharge port 19 as shown by an arrow c, flows through a gas flow path 20 formed between the inner surface side of the heat-resistant container 23 and the outer surface side of the processing container 2, and is taken into the blower 7. It reaches the mouth and is circulated through the hot air circulation path 11 as shown by the arrow d.

When the waste plastic material 28 in the processing container 2 is heated by a high-temperature gas, the apparent bulk occupied by the waste plastic material 28 is reduced, and in the case of, for example, styrene foam, the waste plastic material 28 The foaming gas contained in the styrene is separated, and a part of the styrene is vaporized to reduce the volume. That is, when the waste plastic material 28 is heated, it shrinks while keeping its original shape substantially, and its bulk is significantly reduced. Then, in order to further reduce the volume and to increase the volume reduction rate, the material is compressed by the pressurizing part 3 while heating is started while being heated with a high-temperature gas. However, in the case of PET bottles, etc., if heating proceeds too much, it will crystallize and become hard,
It is necessary to finish pressurizing by then. When the pressure regulating valve 13 is closed and the air pump 22 is operated, air is pressure-fed to the pressurizing actuator 4 composed of an air bag or the like, and the piston 26 moves as shown by an arrow g, and the waste plastic material 28 in the processing vessel 2 is moved. Is compressed between the opening and closing lid 6 to reduce the volume. The waste plastic material 28 whose volume has been reduced and its volume has been reduced is collected, collected for several days, and collected and recycled by a collection company.

By the way, when the newly foamed styrofoam or the like is heated and softened in the waste plastic volume reducing device 1, a larger amount of gas is generated than when the old waste styrofoam is heated and softened. Then, the flammable gas concentration of the high-temperature gas in the processing container 2 increases, and the concentration increases to near the flammable concentration. As a result, the calorific value of the oxidation catalyst increases, and the activation temperature at which the oxidation catalyst starts oxidation (usually about 200 ° C. to 400 ° C.) is 100 ° C. to 200 ° C.
The catalyst downstream temperature, that is, the temperature of the oxidized exhaust gas, continues to rise past the high catalyst heating temperature (about 500 ° C. in the case of styrene foam as described above), and the high-concentration high-temperature gas rapidly burns to oxidize the oxidation catalyst. Damage.

On the other hand, in the first embodiment, if the temperature of the oxidized exhaust gas is detected to be 750 ° C. or more during the operation, the catalyst upstream temperature sensor 17 detects the catalyst upstream temperature, Even if the temperature of the heated exhaust gas is a normal temperature, that is, about 500 ° C., the detection signal of the catalyst downstream temperature sensor 18 is transmitted to the control unit 25.
Then, the power supply to the heating unit 8 and the catalyst heating unit 16 is stopped. As a result, the heating by the catalyst heating unit 16 is suppressed (stopped), the temperature of the oxidation catalyst decreases from the uncontrollable temperature equal to or higher than the activation temperature, and the generation of combustible gas generated in the high-temperature gas also stops. Even if the temperature of the exhaust gas heated by the catalyst upstream temperature sensor 17 is 600 ° C. or higher even if the temperature of the catalyst downstream temperature detected by the catalyst downstream temperature sensor 18, that is, the temperature of the oxidized exhaust gas is 750 ° C. or less, the catalyst downstream The detection signal of the temperature sensor 18 is transmitted to the control unit 25, and the power supply to the heating unit 8 and the catalyst heating unit 16 is stopped. As a result, the heating by the catalyst heating unit 16 is similarly suppressed, the temperature of the oxidation catalyst is lowered from the uncontrollable temperature, and the generation of combustible gas generated in the high-temperature gas is stopped.

As described above, the catalyst downstream temperature sensor 18
When the temperature of 50 ° C. or higher is detected, the power supply to the heating unit 8 and the catalyst heating unit 16 is stopped because (1) the oxidation catalyst is not raised from an appropriate temperature lower than the flammable temperature of the flammable gas, and (2)
Even if the catalyst upstream temperature is normal, if the exhaust gas rises to this temperature, it means that the concentration of flammable gas has approached the flammable concentration and the amount of heat generation has increased. That's why. Since the temperature of 750 ° C. is detected and controlled as described above, the possibility that the flammable gas in the high-temperature gas becomes flammable can be prevented beforehand. It is possible to stop the heating of the high-temperature gas and the heating of the oxidation catalyst to terminate the operation, thereby achieving safety.

The catalyst upstream temperature sensor 17 detects 600 ° C.
If it is detected that the temperature is above, the temperature of the oxidized exhaust gas is 75
Even when the temperature is 0 ° C. or less, the current supply to the heating unit 8 and the catalyst heating unit 16 is stopped because (1) the oxidation catalyst is not raised from an appropriate temperature equal to or lower than the flammable temperature of the flammable gas; Although the heat generation has not yet occurred sufficiently, the concentration of flammable gas is high due to the exhaust gas temperature at the inlet of the oxidation catalyst exceeding 600 ° C., and the possibility that the oxidation catalyst falls into a state in which temperature control is impossible is extremely high. Because it has become. As a result, the possibility that the flammable gas becomes flammable concentration can be prevented beforehand, and a state in which the temperature of the oxidation catalyst cannot be controlled due to generation of a large amount of flammable gas can be prevented, and the operation can be safely terminated. Moreover, since the temperature is controlled by the two temperature sensors of the catalyst upstream temperature sensor 17 and the catalyst downstream temperature sensor 18, high reliability and double safety can be achieved.
It is possible to reliably detect before the flammable gas in the high-temperature gas reaches the flammable concentration. In the case of controlling with either temperature sensor, the processing vessel 2
The high temperature gas in the inside is circulated and cooled by the blower 7 which is always energized from the start of operation, and when the detection temperature of the heating unit temperature sensor 9 decreases to 50 ° C., it is determined that the temperature has decreased to a safe temperature for work, The operation is terminated by releasing a safety lock (not shown) provided on the opening / closing lid 6.
As described above, in the first embodiment, the catalyst downstream temperature sensor 1
8, when the temperature of 750 ° C. is detected or when the upstream temperature sensor of the catalyst detects 600 ° C., the heating is stopped to prevent the generation of gas in the processing vessel 2 and to cool the gas. The disabled state can be reliably prevented beforehand, and the operation can be safely terminated.

(Embodiment 2) Next, another embodiment which is effective for processing when a large amount of gas is generated will be described. In the first embodiment, the detection temperature of the catalyst downstream temperature sensor 18, that is, the temperature of the oxidized exhaust gas is 750 ° C. or more, or the detection temperature of the catalyst upstream temperature sensor 17, that is, the temperature of the heated exhaust gas is 600 ° C. or more. For example, the power supply to the heating unit and the catalyst heating unit was unconditionally terminated, and the operation was terminated. On the other hand, in the second embodiment, when the detection temperature of the catalyst downstream temperature sensor 18, that is, the temperature of the oxidized exhaust gas is detected to be 600 ° C. or more, the detection signal is transmitted to the control unit 25 and only the catalyst heating unit is detected. The energization is interrupted, and when the temperature detected by the catalyst downstream temperature sensor 18, that is, the temperature of the oxidized exhaust gas is reduced to 500 ° C. or less, the energization of the catalyst heating unit is started again, and the catalyst heating unit 16 is turned on and off. The heating softening treatment is continued while preventing the temperature control of the oxidation catalyst from being impossible. Even if the catalyst downstream temperature sensor 18 detects 600 ° C. or more and interrupts the energization of only the catalyst heating unit, if the temperature of the oxidized exhaust gas continues to rise and reaches 700 ° C. or more, the energization of the heating unit 8 is also stopped. The operation is stopped, the high-temperature gas in the processing container is cooled as in the first embodiment, and the operation is terminated. That is, in Embodiment 2, although the calorific value is increased by the oxidation treatment in the oxidation catalyst, the heating softening treatment is continued when the temperature of the exhaust gas can be controlled at 600 ° C. If the temperature of the exhaust gas becomes uncontrollable at 700 ° C. due to abnormal heat generation, this indicates that the flammable gas concentration in the exhaust gas has increased and approached the flammable concentration. The power supply to the catalyst heating unit is stopped, and the high-temperature gas in the processing container 2 is cooled to terminate the operation. Therefore, in the case of the second embodiment, even when a large amount of flammable gas is generated, if the temperature of the oxidation catalyst rises to such a degree that the processing can be continued, the operation can be continued without unnecessary stopping of the processing.

[0029]

As is apparent from the above description, the waste plastic volume reducing apparatus of the present invention is provided with a catalyst heating section, a catalyst upstream temperature sensor, and a catalyst downstream temperature sensor. The flammable gas can be reliably detected before reaching the flammable concentration, and the heating of the high-temperature gas and the temperature rise of the oxidation catalyst can be prevented. The time required for the heat softening treatment is short, and since no gas sensor or the like is used, heat resistance and life are excellent.

Further, when the detection signal from the catalyst upstream temperature sensor reaches a predetermined temperature or higher, the heating of the heating section and the catalyst heating section is stopped, so that a state in which the temperature of the oxidation catalyst cannot be controlled due to generation of a large amount of combustible gas is prevented. Driving can be safely terminated. Similarly, when the detection signal from the catalyst downstream temperature sensor reaches a predetermined temperature or higher, the heating of the heating unit and the catalyst heating unit is stopped, so that it is possible to prevent a state in which the temperature of the oxidation catalyst cannot be controlled due to generation of a large amount of combustible gas. Operation can be safely completed.

When the detection signal from the catalyst downstream temperature sensor reaches a predetermined first temperature or higher, the heating of the catalyst heating section is interrupted, and thereafter, the detection signal from the catalyst downstream temperature sensor falls below the predetermined second temperature. When the temperature decreases, the heating of the catalyst heating unit is restarted. When the detection signal from the catalyst downstream temperature sensor rises to a third temperature or higher exceeding the second temperature, the heating of the heating unit is stopped. When the temperature of the treated exhaust gas is not abnormally high, the concentration of the flammable gas is low, so that the catalyst heating section can be turned on and off to continue the heating softening treatment. When the gas concentration approaches the flammable concentration, it is possible to suppress the flammable gas concentrations in the high-temperature gas and the exhaust gas from increasing.

Further, the method for operating the waste plastic volume reducing apparatus of the present invention can reliably prevent the flammable gas in the high-temperature gas from reaching the flammable concentration. When the temperature of the oxidized exhaust gas is equal to or lower than a predetermined temperature, the heating and softening process is continued while preventing the temperature control from being impossible.If the temperature of the oxidized exhaust gas becomes abnormally high and approaches the flammable concentration, the high-temperature gas It is safe because the flammable gas concentration can be prevented from rising.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a waste plastic volume reducing apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 waste plastic volume reduction device 2 processing container 3 pressurizing unit 4 pressurizing actuator 5 O-ring elastic body 6 opening and closing lid 7 blower 8 heating unit 9 heating unit temperature sensor 10 hot air discharge port 11 hot air circulation path 12 discharge path 12a discharge port DESCRIPTION OF SYMBOLS 13 Pressure control valve 14 Oxidation part 15 Oxidation catalyst 16 Catalyst heating part 17 Catalyst upstream temperature sensor 18 Catalyst downstream temperature sensor 19 Side discharge port 20 Gas flow path 21 Processing gas exhaust port 22 Air pump 23 Heat-resistant container 24 Air suction port 25 Control part 26 Piston 27 Gallery 28 Waste plastic material

Claims (6)

[Claims] A processing container provided with an opening / closing lid and capable of softening waste plastic material therein; a pressurizing unit provided at a bottom side of the processing container to pressurize and reduce the volume of the softened waste plastic material; A hot air circulation path communicating with the processing container and circulating a high-temperature gas for softening waste plastic material, and a discharge path communicating with the hot air circulation path and discharging a part of the high-temperature gas circulating through the hot air circulation path, A blower provided in the hot air circulation path, a heating unit for heating the gas, and an oxidizing unit having an oxidation catalyst for oxidizing exhaust gas to be discharged in the discharge path, and a high-temperature gas circulating in the hot air circulation path. A heating unit temperature sensor for detecting the temperature of the exhaust gas is provided, and the oxidizing unit includes a catalyst heating unit for heating the exhaust gas, a catalyst upstream temperature sensor for detecting the temperature of the heated exhaust gas, and a oxidizing exhaust gas sensor. A catalyst downstream temperature sensor for detecting the temperature, and when the oxidation catalyst reaches a predetermined temperature equal to or higher than the activation temperature, the heating unit and the catalyst heating are detected by a detection signal from the catalyst upstream temperature sensor or the catalyst downstream temperature sensor. A waste plastic volume reducing device, comprising a control unit for suppressing heating by the unit. 2. The waste plastic reducing device according to claim 1, wherein the control unit stops heating the heating unit and the catalyst heating unit when a detection signal from the catalyst upstream temperature sensor reaches a predetermined temperature or higher. Storage device. 3. The waste plastic reduction apparatus according to claim 1, wherein the control unit stops heating the heating unit and the catalyst heating unit when a detection signal from the catalyst downstream temperature sensor reaches a predetermined temperature or higher. Storage device. 4. The control unit interrupts the heating of the catalyst heating unit when the detection signal from the catalyst downstream temperature sensor reaches a predetermined first temperature or higher, and thereafter, the detection signal from the catalyst downstream temperature sensor receives the predetermined signal. When the temperature falls below the second temperature, the heating of the catalyst heating unit is restarted. When the detection signal from the catalyst downstream temperature sensor rises to a third temperature or more that exceeds the second temperature, the heating of the heating unit is stopped. The waste plastic volume reducing apparatus according to claim 1, wherein the heating is stopped. 5. When the concentration of flammable gas contained in the exhaust gas partially discharged from the circulating high-temperature gas rises and the temperature of the oxidized exhaust gas rises to a predetermined temperature, the heating of the catalyst heating unit is stopped. A method for operating a waste plastic volume reducing device, comprising: 6. When the concentration of combustible gas contained in the gas partially discharged from the circulating high-temperature gas rises and the temperature of the oxidized exhaust gas rises to a predetermined first temperature, the catalyst heating section Heating is temporarily stopped, and then, when the temperature of the oxidized exhaust gas decreases to the predetermined second temperature, heating of the catalyst heating unit is restarted. When the temperature of the oxidized exhaust gas rises and reaches the predetermined third temperature, heating is performed. A method for operating a waste plastic volume reducing device, wherein heating of a part is stopped.