JPH09155865A - Apparatus for reducing volume of waste plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely perform oxidation treatment without discharging combustible gas to the outside by providing an oxidation treatment part oxidizing combustible gas generated from a waste plastic to discharge the same to a discharge passage. SOLUTION: When foamed polystyrene is softened, butane gas separated from foamed polystyrene and styrene monomer gas are generated as combustible gases. Then, a part of circulating hot air is branched to a discharge passage 12 and combustible gases are oxidized and deodorized in an oxidation treatment part 14 to be discharged out of the system. Exhaust gas containing the combustible gases is heated to about 400-500 deg.C by the exhaust gas heating part 16 provided to the oxidation treatment part 14 and passed through a combustion catalyst 15 to be burnt and oxidized and purified gas is discharged from an oxidized gas discharged part 20.

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 device for heat-softening and reducing the volume of waste plastic materials such as expanded polystyrene generated in homes, businesses, stores and the like.

[0002]

2. Description of the Related Art Conventionally, a large amount of waste is discharged from homes, business establishments, stores, etc., due to lack of capacity of treatment facilities such as incineration and landfill, and increase in treatment costs including collection and transportation. Measures are urgently needed. As a countermeasure, reducing the amount of waste discharged is the fundamental solution, but recycling as a resource is also extremely effective. Above all, waste plastic materials are attracting attention as a target for recycling because the raw materials are petroleum, a valuable energy resource, and they do not rot even if they are landfilled and are bulky. Among them, expanded polystyrene is often used as a distribution container because of its light weight, cushioning property, low cost, etc., and since no substitute material has been found so far, it is strongly recommended to recycle and reuse it. Is desired. However, when the expanded polystyrene or the like is collected and collected in one place for recycling, there is a problem that since it is bulky, the transportation cost becomes high, which increases the entire recycling cost. For this reason, a volume reduction method and a volume reduction apparatus which are installed in a place where waste plastic material is generated, such as a home, a business place, a store, and the like, to reduce the volume thereof, have been proposed. This volume reducing device softens expanded polystyrene and the like by heating to form a softened solid material. The softened solid material obtained by reducing the volume in this way is collected by a trader and recycled in a recycling plant.

However, when the expanded polystyrene is heated to reduce its volume, foamed gas and the like mixed during foaming of the expanded polystyrene are generated. Moreover, due to the regulation of the use of freon gas, this foaming gas is often mixed with combustible gases such as butane, toluene and xylene. The monomer gas and the like are mixed and discharged. The discharged gas is diluted with the atmosphere and diffuses, but when these gases stored and concentrated in the volume reduction device come into contact with oxygen in the atmosphere, they ignite,
There is a problem in that it burns to a high temperature, damages the volume reduction device, and must consider the effect on the operator.

Therefore, as an improved version of this volume reduction processing apparatus, the following technology (Japanese Patent Laid-Open No. 7-32361) has been conventionally proposed. In this technique, the processing chamber is evacuated to shut off the atmosphere so that the polystyrene foam does not burn even when heated to the melting temperature.

[0005]

However, the apparatus for processing expanded polystyrene disclosed in Japanese Patent Laid-Open No. 7-32361 is easy to use as a recycled raw material because the expanded polystyrene is not burned and is kept as a raw material component. However, there has been a problem that a device for vacuum evacuation becomes large and a large installation area is required. Further, there is a problem that the processing apparatus becomes expensive and is not suitable for general households. In addition, the flammable gas contained in the vacuum-exhausted gas must be treated by separately providing a treatment device.

Therefore, the present invention solves the above-mentioned problems of the prior art and has a simple structure. It is possible to safely oxidize the combustible gas without discharging it to the outside, and to reduce the volume with a simple operation. It is an object of the present invention to provide a lightweight waste plastic volume reducing device.

[0007]

In order to achieve the above object, the waste plastic volume reducing apparatus of the present invention is provided with a heating section for heating a blower and a circulating gas in a hot air circulation path, and a waste plastic volume in an exhaust path. It is characterized in that it is provided with an oxidation treatment section for oxidizing and discharging the combustible gas generated from the above, and is configured to block the propagation of the flashback from the oxidation treatment section to the processing container side.

As a result, it has a simple structure and can be safely oxidized without discharging the flammable gas to the outside.
The volume can be reduced with a simple operation.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention comprises a processing container having an opening / closing lid and storing waste plastic to soften it, and pressurizing the softened plastic provided in the processing container. The hot air circulation passage is provided with a pressurizing unit for reducing the volume, a hot air circulation passage communicating with the processing container for circulating hot air, and an exhaust passage communicating with the hot air circulation passage for discharging a part of the gas circulating in the hot air circulation passage. Is equipped with a blower and a heating unit that heats the circulating gas, and an oxidation treatment unit that oxidizes and discharges the flammable gas generated from waste plastic is provided in the discharge passage, and the oxidation treatment unit is installed to the processing container side. It is designed to block the propagation of fire, and has the action of preventing the flammable gas in the processing container from catching fire and burning.

The invention according to claim 2 further comprises a processing container having an opening / closing lid and storing and softening the waste plastic, and a pressurization for compressing and reducing the volume of the waste plastic softened in the processing container. A portion, a hot air circulation path that communicates with the processing container and circulates hot air, and an exhaust path that communicates with the hot air circulation path and discharges a portion of the gas that circulates in the hot air circulation path,
An air blower and a heating unit for heating the circulating gas are provided in the hot air circulation path, and an oxidation processing section for oxidizing and discharging the combustible gas generated from waste plastic is provided in the discharge path, and a processing container side from the oxidation processing section. And a flame extinguishing unit for blocking the propagation of flashback to the flame. The flame that has flashed back is stopped by the flame extinguishing unit and extinguished.

Further, according to a third aspect of the present invention, a flow velocity sensor for detecting the flow velocity of the gas to be discharged is provided in the discharge passage, and when the gas is reduced to a predetermined flow velocity or less by the detection signal from the flow velocity sensor, the oxidation processing unit is provided. It is equipped with a control unit that reduces or stops the amount of heat supplied to the gas in order to detect the fact that the flow rate is lower than a predetermined flow rate and prevent the occurrence of flashback. Have.

Further, according to the invention as set forth in claim 4, a flow rate sensor for detecting the flow rate of the gas to be discharged is provided in the discharge path, and when the flow rate sensor detects that the flow rate is below a predetermined flow rate, the gas is discharged in the oxidation processing section. And a control unit for reducing or stopping the amount of heat supplied to the heat treatment unit, and has an action of lowering the temperature of the oxidation treatment unit in order to prevent the occurrence of flashback by detecting when the flow rate is below a predetermined flow rate.

According to a fifth aspect of the present invention, a pressure sensor for detecting the pressure of the gas to be discharged is provided in the discharge passage, and a gas is detected in the oxidation processing unit when the pressure falls below a predetermined pressure according to a detection signal from the pressure sensor. And a control unit for reducing or stopping the amount of heat supplied to the device, and has an action of lowering the temperature of the oxidation processing unit in order to detect occurrence of flashback by detecting when the pressure becomes lower than a predetermined pressure.

Further, in the invention according to claim 6, a first temperature sensor for detecting the temperature of the circulating gas in the hot air circulation path and a second temperature sensor for detecting the temperature of the exhaust gas in the discharge path. And a first temperature sensor and a second temperature sensor, respectively.
The temperature difference calculated from the detection signal from the temperature sensor has a control unit that reduces or stops the amount of heat supplied to the gas from the heating unit when the temperature difference reaches or exceeds a predetermined temperature difference,
It has an effect of detecting an abnormality in the hot air circulation path and the discharge path, and detecting a temperature difference equal to or more than a predetermined temperature to reduce the temperature of the oxidation treatment section in order to prevent the occurrence of flashback.

Further, in the invention according to claim 7, a gas sensor for detecting the component concentration of the gas to be discharged is provided in the discharge passage, and the gas is supplied to the gas from the heating unit when the concentration exceeds a predetermined concentration by a detection signal from the gas sensor. The temperature of the oxidation treatment section is controlled to prevent the occurrence of flashback by detecting the abnormality of the discharge path and detecting that the concentration of the constituent exceeds a predetermined level. Has the effect of reducing

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1A is a side sectional view of a waste plastic volume reducing apparatus according to an embodiment of the present invention.
FIG. 3B is a side sectional view of a quenching portion of the waste plastic volume reducing device according to the embodiment of the present invention. FIG. 1 (a), FIG.
In (b), reference numeral 1 is a main body of a waste plastic volume reducing apparatus, which is provided therein with a heat resistant container 22 and a processing container 2 for accommodating and softening the waste plastic material. This heat resistant container 22
Has a structure in which hot air of about 200 ° C. does not leak out of the main body 1, and a suitable material thereof is heat-resistant plastic or the like. As the material of the processing container 2, a material having good thermal conductivity, excellent heat resistance, and a softened plastic material which is not easily welded, or a material whose surface is subjected to a non-adhesive treatment such as a fluororesin coating is suitable. An appropriate number of hot air side discharge ports 18 are provided on the side surface side of the processing container 2, and an opening / closing lid 6 having an O-ring elastic body 5 is provided on the upper surface side thereof. The open / close lid 6 is opened when the waste plastic material is put into the processing container 2, and is closed and closed when the waste plastic material is softened in the processing container 2 and the volume is reduced. Furthermore, the processing container 2
Upward and downward movable pressure part 3 is provided on the bottom side of
The waste plastic material softened by a certain amount of hot air is pressed against the open / close lid 6 to reduce the volume. The pressurizing unit 3 is composed of a pressurizing actuator 4 and a piston that directly pressurizes. The pressurizing actuator 4 is a stretchable rubber balloon-shaped air bag, which is inflated by the air pumped from the air pump 21 to push up the pressurizing portion 3 to reduce the volume of waste plastic material, and thereafter the pressure control valve 13 When opened, the air is discharged and the pressurizing portion 3 is pushed down to return to the original position. The waste plastic material does not leak outside due to the O-ring elastic body 5. At this time, the air pressure to be pumped may be about 0.1 Kg / cm ² , and if the area of the pressurizing section 3 is 1000 cm ² , a pressing force of about 100 kg will be obtained.

A blower 7 has a capacity of about 3000 liters / minute and is provided in a hot air circulation path 11 communicating with the processing container 2 and circulates the hot air into the processing container 2 to blow it. Further, the hot air circulation passage 11 is provided with a heating part 8 which is an electric heater for heating the circulating gas, and a first temperature sensor 9a is provided in the hot air circulation passage 11 near the hot air outlet 10.
The controller 24 controls the temperature of the hot air detected by the first temperature sensor 9a.
The electric power transmitted to the heating unit 8 is controlled by switching a switch circuit or the like to adjust the temperature range to 160 ° C. or less. Reference numeral 12 denotes an exhaust passage, one end of which is communicated with the hot air circulation passage 11, and a part of the circulating hot air is branched and discharged to the outside of the system. Here, the diameters of the hot air circulation port 11a and the exhaust port 12a are selected so that the hot air containing the combustible gas at a flow rate of about 60 liters / minute is discharged to the discharge passage 12. The combustible gas is a mixture of a foaming gas such as butane, toluene, and xylene, and a styrene monomer gas vaporized during the volume reduction treatment. At the other end of the discharge passage 12, an oxidation processing unit 14 that oxidizes the combustible gas discharged and burns it without flame is provided, and the oxidation processing unit 14 has the exhaust gas heated by the exhaust gas heating unit 16. A combustion catalyst 15 for accelerating the oxidation of the exhaust gas and an exhaust gas temperature sensor 1 for detecting the temperature of the exhaust gas that is oxidized and discharged.
7 and an oxidizing gas discharge port 20 are provided.

Reference numeral 30 denotes a flame extinguishing unit which is provided in the discharge passage 12 and is one of flashback shutoff means for shutting off the propagation of the flashback from the oxidation treatment unit 14 to the processing container 2 side. As shown in FIG. 1 (b), the structure of the flame-extinguishing section 30 is a mesh, and its material is preferably a heat-resistant metal or porous ceramic. As will be described later, the mesh has a mesh roughness of 1.0 mm ² or less. With such a configuration, there is a backfire caused by a decrease in pressure in the processing container 2, an increase in combustible gas components, a decrease in the flow rate of hot air containing combustible gas flowing through the discharge passage 12, and the like. Here, it is possible to prevent the flame from being extinguished and propagating to the processing container 2 side. Reference numeral 23 is an air inlet provided in the heat-resistant container 22, which constantly sucks air from the outside during circulation of hot air. The control unit 24 controls the operation of this waste plastic volume reducing device, and controls the temperature of circulating hot air, the amount of circulating air, the pressure in the pressurizing unit 3, and the like.

The operation of the waste plastic volume reducing apparatus according to the first embodiment having the above-described configuration will be described below with reference to FIG.
A description will be given based on (a) and FIG. 1 (b). The opening / closing lid 6 is opened, and styrofoam of a waste plastic material is put into the processing container 2. Next, the opening / closing lid 6 is hermetically closed, and the blower 7 is energized to start air blowing under the control of the control unit 24, and then the heating unit 8 is energized to heat the circulating gas. The heating temperature at this time is about 120 to 160 ° C., and the first temperature sensor 9a detects this, and the detection signal is transmitted to the control unit 24 so as to be maintained at a constant temperature. The hot air is discharged from the hot air discharge port 10 into the processing container 2 as indicated by an arrow b, and heats the expanded polystyrene charged in the processing container 2 to soften a part thereof. Next, the hot air is discharged from the side discharge port 18 as shown by the arrow c, flows through the gas flow passage 19 formed between the heat resistant container 22 and the inner surface thereof, and reaches the intake port of the blower 7, and is shown by the arrow d. Thus, the hot air circulation path 11 is circulated. In this way, the hot air circulates to soften the styrofoam and reduce its volume. When the Styrofoam in the processing container 2 is softened, the apparent volume occupied by the Styrofoam tray or the like becomes smaller and the volume becomes substantially real, and the foaming gas contained in the foaming portion from the beginning is separated. The volume of the styrene is reduced due to vaporization of a part of the styrene, and the pressure is compressed by the pressure unit 3 in order to further reduce the volume and increase the volume reduction rate. When the pressure control valve 13 is closed and the air pump 21 is operated, air is pressure-fed to the pressurizing actuator 4 such as an air bag, and the pressurizing unit 3 transfers the foamed plastic material in the processing container 2 to the open / close lid 6. In the case of a rectangular container after compression, the volume is reduced to a substantially square shape.

When softening styrofoam, butane gas and the like separated from styrofoam as combustible gas and styrene monomer gas are generated as described above. The hot air containing the combustible gas gradually increases its concentration while circulating, and when the hot air approaches the flammable concentration range, it burns rapidly and damages the main body 1. It is also necessary to ensure the safety of the operator, and the styrene monomer gas is flammable and has a strong irritating odor, and if hot air containing a part of these flammable gases is discharged from the system as it is, it will cause discomfort to the surroundings. Not preferable to give. Therefore, a part of the circulating hot air is branched to the discharge path 12, and the oxidizing process section 14 oxidizes the combustible gas and at the same time makes it odorless and discharges it out of the system.
The exhaust gas heating unit 16 provided in the oxidation processing unit 14 heats the exhaust gas containing the combustible gas to about 400 to 500 ° C., passes through the combustion catalyst 15, and is burnt and oxidized, and the purified gas is the exhausted gas. It is discharged from the outlet 20. By passing the heated exhaust gas through the combustion catalyst 15, it is possible to safely burn the combustible gas in a flameless manner, and therefore, the backfire is not propagated to the processing container 2 side. However, the concentration of combustible gas suddenly rises, and the combustion catalyst 1
If an abnormality such as solid flammable material stays in 5,
Flame combustion may occur in the oxidation processing unit 14. The flame generated in the flame burning state propagates by backfire in the discharge passage 12 and propagates to the processing container 2 side.
The extinguishing section 30 provided in the discharge path 12 extinguishes the flame that has flashed back.

Therefore, the structure and effect of the flame extinguishing section 30 will be described below. About 60 Styrofoam is added to the processing container 2.
Introduce 0 g, energize the heating part 8 while circulating air by the blower 7, first circulate and heat hot air of about 120 ° C., and then gradually raise the temperature to about 150 ° C. over about 20 minutes. The styrofoam was uniformly heated to soften it, then the temperature was lowered to 100 ° C., and the pressure was compressed in the pressure unit 3 to reduce the volume. Circulation volume of hot air during this volume reduction operation is approximately 2000
L / min, about 60 L / min of which is discharged to the discharge passage 12. The main component of the combustible gas contained in the circulating gas was butane gas, and its concentration was about 5000 ppm during normal operation. Therefore, for the flashback test, an experiment was conducted by increasing the gas concentration and using a gas having a concentration of 17,000 ppm. The flammable concentration range of butane gas is 150
It is at least 00 ppm. In this state, the exhaust gas heating unit 16 provided in the oxidation processing unit 14 is heated to 500 ° C., and air is blown backward from the oxidizing gas exhaust port 20 to intentionally process the processing container 2
Flash back to the side. The flame-extinguishing section 30 used here was composed of a wire mesh. The above operation was repeated 100 times, and the roughness of the wire mesh used and the number of times of flashback toward the processing container 2 side were measured and shown in Table 1.

[0022]

[Table 1]

In Table 1, the average roughness of the wire mesh is 0.5.
The number of flashbacks at that time was measured and represented by changing the value within a range of up to 4.0 mm ² . Mesh size of a wire mesh used for quenching unit 30 from this that can interrupt propagation of flashback when the average 1.0 mm ² or less, blocking the propagation of generally backfire on average 1.4 mm ² or less can do. On the other hand, when the average mesh size of the wire mesh is 2.3 mm ² or more, it can be seen that the backfire is frequently propagated. And if the average roughness of the wire mesh is 1.0 mm ² or less, the gas concentration is 30
Even when it was increased to 000 ppm, flashback never occurred. When a wire net is used for the flame-extinguishing portion 30 as described above, the average roughness of the mesh may be 1.0 mm ² or less. Moreover, the flame-extinguishing effect can be further enhanced by using a plurality of wire nets in a stacked manner to increase the thickness of the flame-extinguishing section 30.

(Embodiment 2) Next, the means for detecting the flow velocity of the exhaust gas of the present invention and interrupting the propagation of flashback will be described with reference to FIG. 2A is a side sectional view of a waste plastic volume reducing device according to another embodiment of the present invention, and FIG. 2B is a waste plastic volume reducing apparatus according to another embodiment of the present invention. It is a side sectional view of a flow velocity sensor of the device. 2A and 2B are the same as those in FIGS. 1A and 2B, the description thereof is omitted here.
A flow velocity sensor 34 is provided with a flow velocity sensor 34a and is provided at a position in the discharge path 12 where the flow velocity can be measured. This flow velocity sensor 34 is called a heat ray anemometer and measures the flow velocity by detecting the temperature that changes according to the flow velocity of the gas that comes into contact with the heat wire part made of platinum wire or the like provided in the flow velocity sensing part 34a, and extracts it as a voltage change. It is transmitted to the control unit 24. The volume reduction operation of the waste plastic material here is the same as described in (Embodiment 1). During normal operation, the discharge passage 12 having a diameter of 15 mmφ contains about 5000 ppm of combustible gas and the temperature is about 130 ° C.
Exhaust gas with a flow rate of about 60 liters / minute is flowing down,
The flow rate was about 30 cm / sec. This flow velocity is sufficiently faster than the propagation speed of the flashback, and the flashback does not propagate to the processing container 2 side. However, when the exhaust passage 12 is clogged during the volume reduction operation, or when an abnormality occurs in the oxidation processing unit 14 and the flow velocity of the exhaust gas flowing down the exhaust passage 12 is reduced, the pressure is reduced, which causes the propagation of the flashback. Will occur. In this Embodiment 2, it was observed that the flashback propagates when the flow velocity is reduced to about 10 cm / sec or less. In this way, the propagation of flashback can be predicted by detecting that the flow velocity is about 10 cm / sec or less. Here, the flow velocity sensor 34 detects the flow velocity and transmits it to the control unit 24, and when the flow velocity sensor 34 drops below a preset flow velocity, the control unit 24 stops or sharply reduces the power supply to the exhaust gas heating unit 16. Thus, the amount of heat supplied to the gas in the oxidation processing unit 14 for oxidation can be reduced or stopped, and the temperature of the exhaust gas can be lowered to block the propagation of the flashback to the processing container 2 side. In other words, it is possible to block the propagation of flashback by detecting the flow velocity. At the same time, the supply of electric power to the heating unit 8 is stopped or sharply reduced to lower the temperature of the hot air and interrupt the volume reduction processing of the styrofoam.

The flow velocity sensor 34 has good responsiveness, is capable of reliably catching a rapid flow velocity fluctuation, and is easy to maintain. In addition to this, any flow velocity sensor capable of accurately measuring the flow velocity can be used.

(Embodiment 3) Next, a means for detecting the flow rate of exhaust gas and shutting off the propagation of flashback according to the present invention will be described with reference to FIG. FIG. 3 (a) is a side sectional view of a waste plastic volume reducing device according to another embodiment of the present invention, and FIG. 3 (b) is another embodiment of the present invention. It is a sectional side view of a flow sensor of a waste plastic volume reducing device. The functions of the symbols attached to FIGS. 3A and 3B are the same as those in FIGS. 1A and 1B, and therefore will be omitted here. By the way, solid combustibles such as Styrofoam that are partly scattered during the volume reduction operation adhere to the discharge passage 12 and become clogged.
May reduce the flow rate of flammable gas. Particularly, solid combustibles and the like that flow down together with the exhaust gas are likely to be clogged near the exhaust port 12a. Therefore, by measuring the flow rate at the downstream side of the discharge port 12a, it is possible to predict clogging due to solid combustible materials and the like, and prevent the propagation of the flashback to the processing container 2 side caused by the decrease in the flow rate.

Reference numeral 31 is a flow rate sensor having a flow rate sensing portion 31a. This flow rate sensor 31 is called a vortex flow meter, and the gas flowing down the discharge path 12 is provided with a flow rate sensing unit 3 formed of a triangular prism.
The Karaman vortices are generated by arranging the bases of 1a so as to be orthogonal to each other, and temperature changes of the Karman vortices caused by changes in the flow rate are detected by thermistors 31b provided on both sides of the triangular prism, and the flow rate is measured as a voltage change It is transmitted to the control unit 24. The volume reduction operation of the waste plastic material here is the same as described in (Embodiment 1). As mentioned above, when operating normally,
Approximately 50 flammable gases are placed in the discharge path 12 with a diameter of 15 mmφ.
Exhaust gas is flowing down at a flow rate of about 60 liters / min, including 00 ppm at a temperature of about 130 ° C. The concentration of combustible gas is below the combustible concentration range. Greater than velocity, no flashback occurs. Therefore, for the purpose of the experiment, the crushed material of styrofoam was heated and welded in the vicinity of the discharge port 12a and a part thereof was blocked to perform the measurement. At this time, it was observed that the temperature of the exhaust gas dropped to about 60 ° C, the flow rate dropped to about 20 liters / minute or less, and the flashback propagated because of the flow velocity lower than the propagation speed of the flashback. Was done. By detecting the flow rate in this way, the propagation of flashback can be predicted and blocked. In the second embodiment, the flow rate sensor 31 detects the flow rate and transmits it to the control section 24. When the flow rate reaches or falls below a preset flow rate in the control section 24, the power supply to the exhaust gas heating section 16 is stopped or abruptly. By reducing the amount of heat, the amount of heat supplied to the gas in the oxidation processing unit 14 for oxidation is reduced or stopped, the temperature of the exhaust gas is lowered, and the propagation of the flashback to the processing container 2 side can be blocked. At the same time, the supply of electric power to the heating unit 8 is stopped or sharply reduced to lower the temperature of the hot air and interrupt the volume reduction processing of the styrofoam.

(Embodiment 4) Next, a means for detecting the pressure of exhaust gas and interrupting the propagation of flashback according to the present invention will be described with reference to FIGS. 4 (a), 4 (b) and 5. . FIG. 4 (a) is a side sectional view of a waste plastic volume reducing device according to still another embodiment of the present invention, and FIG.
FIG. 5 is a side cross-sectional view of a pressure sensor of a waste plastic volume reducing device according to yet another embodiment of the present invention. FIG. 5 is a waste plastic reduction device according to yet another embodiment of the present invention. It is a relationship diagram of the pressure of a container device and a flow volume. FIG.
The action of the symbols attached to (a) and FIG. 4 (b) is as shown in FIG.
Since it is the same as FIG. 1B, it is omitted here. In the third embodiment, the flow rate sensor 31 is provided downstream of the discharge port 12a to detect the flow rate of the exhaust gas, and when the flow rate becomes equal to or lower than the predetermined flow rate, the means for interrupting the propagation of the flashback has been described. Instead of directly detecting the flow rate of the exhaust gas, the relationship between the pressure of the exhaust gas and the flow rate is obtained in advance, and the propagation of the flashback can be predicted by detecting the pressure corresponding to the predetermined flow rate. it can.

This means will be described. A pressure sensor 32 is provided downstream of the discharge port 12a and has a diaphragm 32a provided therein. The diaphragm 32a is distorted by the exhaust gas pressure, the degree of this displacement is detected by the differential transformer 32b, etc., and the detected signal is transmitted to the control unit 24.

The volume reducing operation of the waste plastic material here is the same as that described in (Embodiment 1). As mentioned above, the diameter is 15mmφ during normal operation.
The exhaust passage 12 of contains about 5000 ppm of combustible gas,
Exhaust gas is flowing down at a temperature of about 130 ° C and a flow rate of about 60 liters / minute, the concentration of combustible gas is below the combustible concentration range, and the flow rate is sufficiently high that the flow velocity is higher than the propagation speed of flashback. It is large and there is no flashback. The pressure of the exhaust gas at this time was 30 mmH ₂ O. Therefore, when the flow rate was gradually reduced, the state of pressure drop was investigated and shown in FIG. Now the flow rate decreases the flow rate from about 60 l / min to about 30 l / min, the pressure is reduced from about 30mmH ₂ O to about 5mmH ₂ O, temperature became about 60 ° C.. Therefore, set the pressure of flammable gas to about 30 mm.
Lowered in steps from H ₂ O by approximately 5mmH ₂ O to about 5mmH ₂ O, was measured flashback number that occurs when the ignition 50 times the discharge path 12 at each step. As a result, flashback does not occur at all up to a pressure of about 10 mmH ₂ O, but when the pressure is about 5 mmH ₂ O or less, the flow velocity is lower than the propagation speed of flashback, so the number of flashbacks exceeds 40 times and is frequent. Two
A flashback to the side occurred. So here the pressure is about 5
When it becomes less than or equal to mmH ₂ O, the control unit 24 controls the power supply to the exhaust gas heating unit 16 to stop or abruptly decrease, thereby reducing or stopping the heat amount supplied to the gas in the oxidation processing unit 14 for oxidation. Then, the temperature of the exhaust gas can be lowered to block the propagation of the flashback to the processing container 2 side. At the same time, the supply of electric power to the heating unit 8 is stopped or sharply reduced to lower the temperature of the hot air and interrupt the volume reduction processing of the styrofoam.

The pressure sensor 32 is preferably one that can measure the pressure with high accuracy and is easy to maintain. In addition to this, if the pressure sensitive element is composed of a strain gauge or the like, a pressure sensitive one can be obtained.

(Embodiment 5) Next, the means for detecting the temperature difference between the hot air circulating gas and the exhaust gas and shutting off the propagation of the flashback according to the present invention will be described with reference to FIGS. 6 (a), 6 (b) and 7 It will be described based on. FIG. 6A is a side sectional view of a waste plastic volume reducing device according to another embodiment of the present invention.
FIG. 7B is a side sectional view of a temperature sensor of a waste plastic volume reducing device which is another embodiment of the present invention, and FIG. 7 is a temperature difference of the waste plastic volume reducing device which is another embodiment of the present invention. FIG. 6A and 6B are the same as those in FIGS. 1A and 1B, the description thereof is omitted here. In the fourth embodiment, the means for providing the pressure sensor 32 downstream of the exhaust port 12a to detect the pressure of the exhaust gas and detecting when the pressure becomes equal to or lower than the predetermined pressure to interrupt the propagation of the flashback has been described. Instead of the means for detecting the pressure of the exhaust gas, the inside of the hot air circulation path 11 and the exhaust port 12 are preliminarily set.
The propagation of the flashback can be predicted by obtaining the relationship between the temperature difference with the exhaust gas downstream of a and the flow rate, and detecting the temperature difference corresponding to the predetermined flow rate.

This means will be described. Here the first
The temperature sensor 9a is provided near the hot air outlet 10 and the second temperature sensor 9b is provided downstream of the outlet 12a. First
The temperature sensor 9a and the second temperature sensor 9b can detect up to about 200 ° C. like the thermocouple 9c, and the detection signal is sent to the control unit 2.
4 can be transmitted. The controller 24 calculates the temperature difference from the temperatures of the transmitted hot air circulating gas and exhaust gas. As described above, during normal operation, the exhaust passage 12 having a diameter of 15 mm contains about 5000 ppm of combustible gas, and exhaust gas with a flow rate of about 60 liters / minute flows down. The temperature difference between the gas and the exhaust gas is about 20 ° C., the concentration of the combustible gas is within the combustible concentration range, and the flow rate is sufficiently high so that the flow velocity is higher than the propagation speed of the flashback and the flashback does not occur. Then, the relationship between the flow rate and the temperature difference was examined, and the result was as shown in FIG. When the flow rate was reduced from about 60 liters / minute to about 15 liters / minute, the temperature difference correspondingly changed from about 20 ° C to about 90 ° C. Therefore, the flow rate of the exhaust gas is reduced from about 60 liters / minute to about 15 liters / minute in steps of about 15 liters / minute, and the temperature difference between the hot air circulating gas and the exhaust gas at each step and the discharge in that state The number of flashbacks that occurred when the road 12 was ignited 50 times was measured. As a result, flashback did not occur at all until the temperature difference reached about 67 ° C. However, when the temperature difference exceeded about 67 ° C., the flow velocity decreased from the propagation speed of the flashback and the flashback frequently occurred 45 times. Therefore, here, when the temperature difference becomes about 67 ° C. or more, the propagation of the flashback can be predicted, and the control unit 24 controls the power supply to the exhaust gas heating unit 16 to stop or sharply decrease the power, thereby causing oxidation. The amount of heat supplied to the gas in the oxidation processing unit 14 can be reduced or stopped, and the temperature of the exhaust gas can be lowered to block the propagation of the flashback to the processing container 2 side. At the same time, the supply of electric power to the heating unit 8 is stopped or sharply reduced to lower the temperature of the hot air and interrupt the volume reduction processing of the styrofoam.

The first temperature sensor 9a and the second temperature sensor 9b are preferably those which can measure the temperature with high accuracy and are easy to maintain. In addition to this, if the thermistor 31b and the like are used, those having a good temperature response can be obtained. To be

(Embodiment 6) Next, a means for detecting the component concentrations of the combustible gas of the hot air circulating gas and the exhaust gas of the present invention to interrupt the propagation of the flashback is shown in FIGS. 8 (a) and 8 (b). )
It will be described based on. FIG. 8 (a) is a side sectional view of a waste plastic volume reducing device according to still another embodiment of the present invention, and FIG. 8 (b) is a waste plastic volume reducing device according to still another embodiment of the present invention. It is a sectional side view of the gas sensor of an apparatus. The action of the symbols attached to FIGS. 8A and 8B is as shown in FIG.
Since (a) and FIG. 1 (b) are the same, they are omitted here. Here, the gas sensor 33 is provided in the discharge path 12. The gas sensor 33 is composed of a gas sensitive element 33a made of a semiconductor containing tin oxide or the like as a main component, and a flammable gas such as butane gas is adsorbed on its surface to move electrons to change the electric conductivity of the semiconductor. The component concentration is detected and transmitted to the control unit 24. When the volume reduction process is normally performed, the concentration of butane gas contained in the exhaust gas is about 5000 ppm, which is a safe concentration range compared to the flammable range of 15000 ppm, but the discharge passage 12 is clogged during the volume reduction operation.
When an abnormality occurs in the oxidation processing unit 14 and the flow rate of exhaust gas decreases and the amount of gas exhausted from the oxidizing gas exhaust port 20 decreases, the intake of fresh air sucked from the air supply port 23 decreases. The concentration of butane gas and the like in the processing container 2 gradually increases and reaches the flammable range of 15000 ppm or more. Therefore, for example, the upper limit concentration of butane gas is 10
If the concentration is set to 000 ppm, the control unit 24 controls the supply of electric power to the heating unit 8 to stop or abruptly decrease when the concentration exceeds the concentration, thereby reducing or stopping the amount of heat supplied to the gas, By reducing the temperature of the hot air so that the butane gas concentration is 10,000 ppm or less, it is possible to block the propagation of the flashback to the processing container 2 side.

Although the flow velocity sensor 34, the flow rate sensor 31, the pressure sensor 32, the first temperature sensor 9a, the second temperature sensor 9b, and the gas sensor 33 described in the above second to sixth embodiments are individually provided, they are extinguished. It may be provided together with the part 30 to more reliably block the propagation of the flashback to the processing container 2 side, or a plurality of types of sensors may be provided at the same time to predict the flashback with higher accuracy and safely reduce the melting process. it can.

[0037]

As is apparent from the above, the waste plastic volume reducing apparatus of the present invention is provided with an oxidation treatment section for oxidizing and discharging the combustible gas generated from the waste plastic material in the discharge path, and the treatment is performed from the oxidation treatment section. This is intended to block the backfire from propagating to the container side, and has the effect that the oxidizing treatment can be performed safely without discharging the flammable gas to the outside, and the volume reduction treatment can be performed by a simple operation.

Further, since the flame-extinguishing portion is provided, the structure can be simplified, the volume can be safely reduced, and the size and weight can be reduced.

Further, since a flow velocity sensor is provided and the amount of heat supplied by the control unit is reduced or stopped, the propagation of flashback can be blocked.

Further, since a flow rate sensor is provided and the amount of heat supplied by the control unit is reduced or stopped, the propagation of flashback can be blocked.

Further, since a pressure sensor is provided and the amount of heat supplied by the control unit is reduced or stopped, the propagation of flashback can be blocked.

Further, since the first temperature sensor and the second temperature sensor are provided and the amount of heat supplied by the control unit is reduced or stopped, the propagation of flashback can be interrupted.

Further, since the exhaust gas sensor is provided and the amount of heat supplied by the controller is reduced or stopped, the propagation of flashback can be blocked.

[Brief description of the drawings]

FIG. 1A is a side sectional view of a waste plastic volume reducing device according to an embodiment of the present invention. FIG. 1B is a side sectional view of a quenching part of a waste plastic volume reducing device according to an embodiment of the present invention.

2A is a side sectional view of a waste plastic volume reducing device according to another embodiment of the present invention. FIG. 2B is a flow rate sensor side of a waste plastic volume reducing device according to another embodiment of the present invention. Cross section

FIG. 3 (a) is a side sectional view of a waste plastic volume reducing device according to another embodiment of the present invention. FIG. 3 (b) is a waste plastic volume reducing device according to another embodiment of the present invention. Side sectional view of flow sensor

FIG. 4A is a side sectional view of a waste plastic volume reducing device according to yet another embodiment of the present invention. FIG. 4B is a waste plastic volume reduction according to yet another embodiment of the present invention. Side sectional view of pressure sensor of device

FIG. 5 is a diagram showing the relationship between the pressure and the flow rate of a waste plastic volume reducing device which is another embodiment of the present invention.

FIG. 6A is a side sectional view of a waste plastic volume reducing device according to another embodiment of the present invention. FIG. 6B is a side sectional view of a temperature sensor of the waste plastic volume reducing device according to another embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a temperature difference and a flow rate of a waste plastic volume reducing device according to another embodiment of the present invention.

FIG. 8A is a side sectional view of a waste plastic volume reducing device according to still another embodiment of the present invention. FIG. 8B is a side sectional view of a gas sensor of the waste plastic volume reducing device according to yet another embodiment of the present invention. Figure

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Processing container 3 Pressurizing part 4 Pressurizing actuator 5 O-ring elastic body 6 Opening / closing lid 7 Blower 8 Heating part 9a 1st temperature sensor 9b 2nd temperature sensor 9c Thermocouple 10 Hot air outlet 11 Hot air circulation path 12 Ejection Line 12a Exhaust port 13 Pressure control valve 14 Oxidation treatment part 15 Combustion catalyst 16 Exhaust gas heating part 17 Exhaust gas temperature sensor 18 Side discharge port 19 Gas flow path 20 Oxidized gas exhaust port 21 Air pump 22 Heat-resistant container 23 Air intake port 24 Control Part 30 Flame-extinguishing part 31 Flow rate sensor 31a Flow rate sensing part 31b Thermistor 32 Pressure sensor 32a Diaphragm 32b Differential transformer 33 Gas sensor 33a Gas sensing element 34 Flow velocity sensor 34a Flow velocity sensing part

Claims (7)

[Claims] 1. A processing container provided with an opening / closing lid for accommodating and softening waste plastic, a pressurizing unit provided in the processing container for pressurizing and reducing the volume of the softened plastic, and a communication part for communicating with the processing container. A hot air circulation passage for circulating the hot air and an exhaust passage communicating with the hot air circulation passage for discharging a part of the gas circulating in the hot air circulation passage, and the hot air circulation passage for heating the gas circulating with the blower. In addition to providing a heating unit to perform, the exhaust passage is provided with an oxidation processing unit that oxidizes and discharges the combustible gas generated from waste plastic, and a backfire is propagated from the oxidation processing unit to the processing container side. Waste plastic volume reduction device characterized by shutting off. 2. A processing container having an opening / closing lid for accommodating and softening waste plastic, a pressurizing unit provided in the processing container for pressurizing and reducing the volume of the softened waste plastic, and a communication unit for communicating with the processing container. A hot air circulation passage for circulating the hot air and an exhaust passage communicating with the hot air circulation passage for discharging a part of the gas circulating in the hot air circulation passage, and the hot air circulation passage for heating the gas circulating with the blower. And a heating unit for oxidizing the combustible gas generated from the waste plastic and discharging it to the discharge path, and blocking the propagation of the flashback from the oxidation processing unit to the processing container side. A waste plastic volume reduction device, which is provided with an extinguishing section. 3. A flow velocity sensor for detecting the flow velocity of the gas to be discharged is provided in the discharge passage, and the gas is supplied to the gas in the oxidation processing unit when the gas is reduced to a predetermined flow velocity or less by a detection signal from the flow velocity sensor. The waste plastic volume reducing device according to claim 1 or 2, further comprising a control unit for reducing or stopping the amount of heat. 4. A flow rate sensor for detecting a flow rate of the gas to be discharged is provided in the discharge passage, and a heat quantity supplied to the gas in the oxidation processing unit when the flow rate is lowered below a predetermined flow rate by a detection signal from the flow rate sensor. The waste plastic volume reducing device according to claim 1 or 2, further comprising: a control unit for reducing or stopping. 5. A pressure sensor for detecting the pressure of the gas to be discharged is provided in the discharge passage, and a heat quantity supplied to the gas in the oxidation processing unit when the pressure falls below a predetermined pressure according to a detection signal from the pressure sensor. The waste plastic volume reducing device according to claim 1 or 2, further comprising: a control unit for reducing or stopping. 6. The hot air circulation passage is provided with a first temperature sensor for detecting the temperature of the circulating gas, and the exhaust passage is provided with a second temperature sensor for detecting the temperature of the exhausted gas. And a controller that reduces or stops the amount of heat supplied to the gas in the oxidation processing unit when the temperature difference calculated from the detection signals from the first temperature sensor and the second temperature sensor reaches a predetermined temperature difference or more. The waste plastic volume reducing device according to claim 1 or 2, characterized in that. 7. A gas sensor for detecting the component concentration of the gas to be discharged in the discharge passage, and reducing the amount of heat supplied to the gas in the oxidation treatment unit when the concentration exceeds a predetermined concentration according to a detection signal from the gas sensor. The waste plastic volume reducing device according to claim 1 or 2, further comprising: a control unit for stopping.