JP2002053697A - Waste plastic dechlorination method and dechlorination equipment - Google Patents

Abstract

(57) [Summary] Dechlorination can be performed at a relatively low temperature and in a short time, and C-Cl bonds can be selectively decomposed, thereby reducing the residual chlorine concentration. Provide a method of dechlorinating waste plastics that can increase the efficiency. A waste plastic containing a chlorine-based resin such as polyvinyl chloride and polyvinylidene chloride is supplied to a continuous twin-screw kneader to be kneaded and melted. Then, a low-pressure mercury lamp (21, 21,...) Is provided at a vent port (6) provided with a kneading disk (12, 12,...) On the downstream side.
…). UV light is irradiated from a low-pressure mercury lamp (21, 21,...) To the waste plastic in a molten state that is undergoing a surface renewal action. The hydrogen chloride generated by the photolysis and the thermal decomposition is exhausted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to polyvinyl chloride,
The present invention relates to a method for dechlorinating waste plastic containing a chlorine-based resin such as polyvinylidene chloride and a dechlorination apparatus for waste plastic used for carrying out this method.

[0002]

2. Description of the Related Art Methods for dechlorination of waste plastics containing chlorine-based resins such as polyvinyl chloride and polyvinylidene chloride can be broadly classified into dechlorination methods by thermal decomposition,
A dechlorination method by photolysis is known. The dechlorination method by thermal decomposition is described, for example, in Reference (A) {M. Michaeli: D
egradtiveextrusion as a pretreatig process for che
mical recycling of plasticswaste, Die Angwandte
As shown in Makromolekurale chemic, 232 (1995)｝, waste plastic containing chlorinated resin is put into a twin-screw or single-screw extruder, and the heat applied from the heating cylinder and the frictional action due to the rotation of the screw Melting by heat generated by shearing action, etc.
A dechlorination method is known in which a chlorine-based resin is thermally decomposed by increasing the temperature to 0 ° C., and hydrogen chloride generated by the pyrolysis is exhausted and removed from a vent port provided on the downstream side of a heating cylinder. Further, a dechlorination method by thermal decomposition is disclosed in
No. 120285, and a method for dechlorination by thermal decomposition has been proposed by the present applicant in Japanese Patent Application No. 11-162125.

[0003] A dechlorination apparatus or a pyrolysis reaction apparatus disclosed in Japanese Patent Application Laid-Open No. 8-120285 has a reaction tube provided with a waste plastic inlet at one end and a hydrogen chloride outlet and a molten plastic outlet at the other end. And a heating means for heating the waste plastic from the outer periphery of the reaction tube, and a transport means for transporting the waste plastic in the reaction tube from the one end to the other end. A molten plastic return port provided at the other end, a molten plastic return flow path connecting the molten waste plastic return port provided at the one end, and an interior for heating waste plastic from inside the reaction tube. And heating means.
The proposed dehydrochlorination apparatus disclosed in Japanese Patent Application No. 11-162125 includes a waste plastic inlet, a molten plastic outlet, a hydrogen chloride outlet, a heating means for heating the waste plastic, and a waste plastic. And a transportation means for transporting the hydrogen from the inlet to the outlet.The hydrogen chloride outlet is removed before the generated hydrogen chloride reacts with the component in the waste plastic to become a high boiling compound which is difficult to remove. Is configured.

On the other hand, a dechlorination method or a dechlorination apparatus mainly using ultraviolet rays is disclosed in JP-A-3-221121, JP-A-49-119972, and JP-A-60-187322.
JP-A-11-160309, JP-A-10-137
748, JP-A-9-53081, JP-A-9-194
625 and the like.

JP-A-3-221121 discloses halogenated hydrocarbons (1,1,2-trichloro-1,2,2-trifluoroethane, trichloromonofluoromethane, dichlorodifluoroethane, chloroform, carbon tetrachloride,
A method is disclosed in which ultraviolet rays such as a low-pressure mercury lamp are irradiated to methyl chloroform or the like in the presence of oxygen to photodecompose halogenated hydrocarbons to render them harmless. According to this method, the carbon-chlorine bond and the carbon-
The fluorine bond can be broken to generate chlorine and fluorine radicals, which can be reacted with a radical scavenger to be immobilized on the radical scavenger. JP-A-49-11997
No. 2 includes spraying or spraying a solution of a decomposition accelerator in a solvent on waste plastic, immersing the waste plastic in the solution, or applying a solution containing the decomposition accelerator to the surface of the waste plastic. Discloses a method of irradiating ultraviolet rays from a high-pressure mercury lamp to accelerate the decomposition of waste plastic. The decomposition accelerator may be a metal halide, an acetylacetone salt of the metal or an alkyl compound thereof, or A comprising a higher aliphatic metal.
This is a mixture of the component and the component B composed of phosphite triester at a specific ratio. By this method, not only polyvinyl chloride but also polyolefin resin and vinyl resin are decomposed. JP A No. 60-187322, a gas, decomposing the harmful substances in the liquid or solid waste, in a method for purifying, _TiO 2, Mo in the reactor
A method is disclosed in which a photocatalyst such as S ₂ or InP and a waste to be treated are charged, and the reactor is irradiated with light having a visible wavelength or an ultraviolet wavelength to decompose harmful substances by a photochemical reaction. . The reactor used to carry out the method comprises:
It is a batch system or a flow reaction system made of glass, quartz glass, etc. that transmits light.Solid waste is dissolved or suspended in a solvent such as water to make it into a liquid phase system, or fine particles are crushed or the like. It is said that it is desirable to treat in a gas phase system suspended in a state.

[0006] JP-A-11-160309 discloses a detection method for detecting the presence of polyvinyl chloride. In other words, high-pressure mercury lamps irradiate ultraviolet light to waste plastic containing polyvinyl chloride sent by the transport device, and the hydrogen chloride gas generated when the polyvinyl chloride is dehydrochlorinated is converted to electrochemical hydrogen chloride. A method for detecting the presence of polyvinyl chloride by detecting with a sensor is shown. Japanese Patent Application Laid-Open No. Hei 10-137748 discloses an apparatus for detoxifying organic chlorine-based harmful substances. Since this detoxifying device has an ultraviolet ray transmitting container and an ultraviolet ray generator,
Organic chlorine-based harmful substances such as polychlorinated biphenyls (PCB) and CFCs are dissolved in a solvent such as isopropyl alcohol (IPA), which is a hydrogen donor, to a concentration of about 100 ppm. To remove chlorine and replace it with hydrogen to make it harmless. Japanese Patent Application Laid-Open No. 9-53081 discloses that a mixed liquid is irradiated with ultraviolet light from a low-pressure mercury lamp while adding an oxidizing agent to a chlorine-containing waste oil containing 3 to 30% of water and stirring and dispersing the mixture. A method is shown in which calcium hydroxide is charged, the mixed solution is gently allowed to stand, and then water and solid components precipitated at the lower portion of the mixed solution are removed. Also, a dechlorination device comprising a mixing tank and a photochemical reaction tank is shown. Are also shown.
Japanese Patent Application Laid-Open No. 9-194625 discloses that a predetermined amount of water in which a powdery metal oxide is dispersed and a powdered organic substance to be treated are sealed in a pressure vessel, and the space inside the pressure vessel is replaced with oxygen. A method of decomposing a polyolefin-based resin and a thermosetting resin by irradiating the contents of the pressure-resistant container with ultraviolet rays by setting the inside of the pressure-resistant container to a supercritical state of water is disclosed. This example shows that 40 to 46% of polyethylene was decomposed in 30 to 60 minutes by this method.

Reference (B) 文献 A. Torikai & H.
Hasegawa: Photo Degradation of Polyvinl Chlorid
e, Polymer Degradation and Stabilitey, 63, p.44
1-445 (1999)｝ states that, among waste plastics, polyolefin-based resin, polystyrene, acrylic resin, and polyvinyl chloride are photo-decomposed by accelerated sunlight with a wavelength of 290 nm or more. When irradiating with ultraviolet light of 254 nm, a conjugated double bond and a carbonyl group are formed, the molecular weight is reduced, and the absorption peak shifts to a longer wavelength region of 400 nm or more, so that photodecomposition by sunlight can be promoted. It has been shown.

[0008]

The dechlorination method by thermal decomposition known from the above-mentioned document A, or the dechlorination method by thermal decomposition proposed in JP-A-8-120285, Japanese Patent Application No. 11-162125 and the like. According to the chlorine method,
By heating to 300 to 390 ° C., the advantage is obtained that as much as 99% of dehydrochlorination is performed continuously and in a short time of 5 to 30 minutes. There is also an advantage that it is not necessary to add an additive or the like to the dechlorination treatment. There are, however, points to be improved. For example, since the treatment is performed at a high temperature, the hydrocarbon content contained in the waste plastic is also decomposed and removed. As a result, when the treatment residue after dechlorination is used as a fuel, the yield as the fuel is not good. More specifically, in the dechlorination treatment of waste plastic, the value to be added is low because the target of the treatment is garbage. Therefore, it is often used as a fuel. In this case, it is desirable to minimize the volatilization of hydrocarbons, which are fuels other than chlorine, in the process of dechlorination and to have a large amount of fuel after dechlorination. When the treatment is performed at a high temperature of 350 ° C. or more,
Although the chlorine content decreases, the hydrocarbon content also evaporates at the same time, and the fuel yield decreases. In addition, although the processing temperature is high, the residual chlorine concentration does not decrease, and other harmful organic chlorine gas may be generated as a secondary product. For example, when polyvinyl chloride is thermally decomposed, hydrogen H ₂ , methane C
H ₄ , ethane C ₂ H ₆ , ethylene C ₂ H ₄ , propane C
There is a possibility that ₃ H ₈ , benzene C ₆ H ₆ , toluene C ₇ H ₈ , xylene and ethylbenzene C ₈ H ₁₀ , naphthalene, carbon, hydrogen chloride HCl and the like may be generated. Further, the generated hydrogen chloride reacts with the inorganic substance, and formation of a high-boiling compound which is difficult to volatilize and remove calcium chloride and the like is inevitable to some extent. The state of this thermal decomposition is shown in FIG. Also, a large amount of energy is required to heat the waste plastic to be treated to a high temperature.

According to the dechlorination method by photolysis, for example, when decomposing and dechlorinating polyvinyl chloride using a photochemical reaction, there is an advantage that the reaction proceeds at a low temperature equal to or higher than the glass transition temperature. In addition, since the C-Cl bond absorbs a short wavelength of 290 nm or less and decomposes, there is an advantage that the C-Cl bond can be selectively cleaved. However, there are many problems to be improved. For example, according to the above-mentioned Japanese Patent Application Laid-Open No. 3-221121, carbon tetrachloride is decomposed by 99% by irradiating ultraviolet rays from a low-pressure mercury lamp of 50 W at 100 ° C. for 2 hours, but this method is applicable to gas. However, there is a drawback that a scavenger for scavenging chlorine radicals is required, and the treatment is required. According to Japanese Patent Application Laid-Open No. 49-119972, there is an advantage that not only polyvinyl chloride but also polyolefin resins and vinyl resins are decomposed. However, this method has a problem that a solvent must be used. Further, it is not possible to selectively decompose only C-Cl bonds of a chlorine-based resin from waste plastics in which several types of plastics are mixed. Further, in the embodiment of the present invention, the photodecomposition reaction is performed at room temperature for solid waste plastic. However, the irradiation time is as long as several tens of hours to 100 hours, and requires a decomposition accelerator. Therefore, it is costly to process a large amount of waste plastic, and there is a possibility that the method cannot be performed. In order to carry out the method described in JP-A-60-187322, a photocatalyst is indispensable, and the reactor is made of glass, quartz glass or the like, and has a drawback that it has poor durability against mechanical force and impact. Furthermore, according to the example relating to the removal of ethyl cellosolve and acetoaldehyde, the removal of the former requires a long time of 3 hours, and the removal of the latter requires a long time of 8 hours. There's a problem.
Further, when the waste plastic is melted, it is difficult to dissolve it in a solvent, and when solid waste plastic is dispersed in fine particles, it takes a long time to decompose the waste plastic because the temperature is low. Furthermore, only C-Cl bonds cannot be selectively decomposed from waste plastics in which several types of plastics are mixed.

The method described in Japanese Patent Application Laid-Open No. 11-160309 is a detection method for detecting the presence of polyvinyl chloride and does not constitute the prior art of the present invention. Unless the plastic is homogeneously stirred and mixed, there is a disadvantage that the polyvinyl chloride hidden under the crushed waste plastic cannot be detected. According to the apparatus for detoxifying an organic chlorine-based harmful substance described in Japanese Patent Application Laid-Open No. Hei 10-137748, there is an advantage that the treatment can be performed at normal temperature and normal pressure and in a completely closed system by irradiating ultraviolet rays. However, since the reaction speed is slow, a high-efficiency and high-output ultraviolet light source is required, and the cost is high. Therefore, a high-efficiency and high-output ultraviolet light source is arranged around a container containing a hydrogen donor solvent in which PCB is dissolved,
It is said that the reaction is accelerated by uniformly irradiating strong ultraviolet rays from the surroundings, a large amount of chlorine in the PCB is eliminated, and the PCB is replaced with hydrogen to render it harmless. However, a solvent as a hydrogen acceptor is indispensable in the present method, and a material obtained by pulverizing waste plastic or a highly viscous melt obtained by heating and melting waste plastic cannot be dissolved in the solvent. Detoxification equipment cannot be applied.
According to the invention described in Japanese Patent Application Laid-Open No. Hei 9-53081, water has an advantage that it functions as an oxidizing agent because it forms hydroxyl radicals by irradiating ultraviolet rays, thereby promoting dechlorination. At this time, it is considered that it is desirable to use 5 to 20% of an oxidizing agent such as oxygen, ozone, hydrogen peroxide, and hydroxyl radical. In the examples of the present invention, a suitable reaction time is 1 to 5 hours. Then, the wavelength 253.7 was added to the chlorine-containing waste oil using a low-pressure mercury lamp.
nm, 4.9 eV (113 kcal / mol), 18
As a result of irradiating ultraviolet rays of 4.9 nm and 6.7 eV (155 kcal / mol) for 3 hours, the dechlorination rate was 94% or more. However, the target of this method is waste oil, and this method cannot uniformly irradiate ultraviolet rays to solid or molten waste plastic. An example is shown in which 40 to 46% of polyethylene is decomposed in 30 to 60 minutes by the method described in JP-A-9-194625, and a certain effect is recognized. However, in order to carry out this method, it is necessary to pulverize the waste plastic, and the temperature and pressure are such that water is in a supercritical state.
There are drawbacks such as the need to maintain the temperature at 4 ° C. and 22.1 MPa or more, the need for a pressure-resistant container, and the need for a metal oxide. Further, it is not possible to selectively decompose only C-Cl bonds of a chlorine-based resin from waste plastics in which several types of plastics are mixed.

The document (B) indicates that photodecomposition can be accelerated by sunlight. From this, it is difficult to determine whether visible light can dechlorinate waste plastic in a short time. Unknown. Further, in the experiment, a film having a thickness of 25 ± 5 μm was used, and this experiment does not suggest that the irradiation is performed in a molten state in which dechlorination by photolysis easily proceeds.

As described above, when waste plastic is used as a fuel after dechlorination by the dechlorination method by thermal decomposition, a large amount of fuel remains and it is necessary to perform dechlorination with low energy. For that purpose, it is desirable to perform a large amount of dechlorination treatment at a temperature as low as possible and in a short time. In particular, if the C-Cl bond can be selectively dissociated at a low temperature, the residual chlorine concentration is reduced, the fuel content is increased, the generation of secondary organic chloride is small, and no high-temperature mechanical material is required. As a result, the equipment cost is reduced, and energy saving and cleanliness can be achieved. However, the above-described conventional method for dechlorination by thermal decomposition cannot satisfy such a demand. Further, according to the dechlorination method by photolysis, for example, when decomposing and dechlorinating polyvinyl chloride, the reaction proceeds at a low temperature higher than the glass transition temperature, and the C-Cl bond absorbs ultraviolet light having a wavelength of 290 nm or less. Can be selectively cleaved C-Cl bond,
All of the above-mentioned conventional methods of photodecomposition dechlorination are performed at relatively low temperatures, and have the disadvantage that the reaction requires an extremely long time of several hours to 100 hours. Further, since the photochemical reaction occurs only in the vicinity of the irradiated surface, there is a disadvantage that the internal dechlorination cannot be performed. However, as disclosed in JP-A-60-187322, the polyvinyl chloride to be treated is dispersed in the form of fine particles in a solvent that transmits ultraviolet light, and this is irradiated with ultraviolet light to perform a dechlorination treatment. However, the pretreatment for dispersing is complicated, and this method cannot be applied to the dechlorination of a large amount of waste plastic.

An object of the present invention is to provide a method and an apparatus for dechlorinating waste plastic which have solved the above-mentioned conventional problems or disadvantages. Dechlorination can be performed in a short time, and C-Cl bond can be selectively decomposed, thereby reducing the residual chlorine concentration, increasing the fuel yield, suppressing the generation of high-boiling chloride, and harmful. An object of the present invention is to provide a method for dechlorinating waste plastic which can suppress generation of chlorine gas and has a large processing capacity, and a dechlorination apparatus used for carrying out the method.

[0014]

The above objects of the present invention can be achieved by low-temperature and selective cleavage of C-Cl bonds by photolysis and other mechanical devices. This is achieved by a combination with the surface renewal action or the thermal decomposition action of the screw kneader. The details will be described below. The twin screw kneader, as is well known,
It comprises a heating cylinder barrel and two screws which are rotationally driven adjacent to each other inside the heating cylinder barrel. A material supply hole is provided at one end of the heating cylinder barrel, a devolatilization port or vent port where the groove of the screw is deepened at the downstream side, and a discharge hole is provided at the downstream end. Such a twin-screw kneader stirs, mixes, heats, melts,
It has the function of transporting it to the front in the axial direction while kneading, and the function of extruding it from the discharge port, but is particularly excellent in the function of distributing and mixing the materials, that is, the function of mixing the materials so that the positions are exchanged in bulk units, and the function of dispersion kneading. In other words, it is excellent in the function of dispersing particles in the order of microns in a crushing manner. At the same time, the vent port of the twin-screw kneader is excellent in the action of constantly renewing the material surface facing the vent port, that is, the surface renewing action.

On the other hand, the photochemical reaction caused by ultraviolet irradiation appears only near the surface of the material. On the other hand, the twin-screw kneader is excellent in the surface renewal action as described above. Therefore, it can be said that the twin-screw kneader has extremely advantageous properties in that a photochemical reaction occurring only in the vicinity of the surface uniformly occurs throughout the material.

Therefore, according to a preferred embodiment of the present invention, an ultraviolet irradiation device, specifically, an ultraviolet lamp is provided at the vent or opening of the heating cylinder barrel of the twin-screw kneader,
While the waste plastic is agitated, mixed, heated, melted and kneaded by the rotation of the twin screw, the waste plastic is simultaneously irradiated with ultraviolet rays from an ultraviolet lamp. As a result, the photodegradation effect exerted only on the vicinity of the surface of the waste plastic acts uniformly on the whole. That is, the photolytic decomposition action of the selective C-Cl bond near the surface at a relatively low temperature and the renewal action of the surface of the twin-screw kneader produce a high-viscosity molten state,
The waste plastics in either the solid state or the solid-melt mixed state can be homogeneously photodegraded. As a result, the waste plastic can be dechlorinated at a low temperature and low energy while keeping a large amount of hydrocarbons as fuel.

The ultraviolet ray generator applied to the present invention includes:
A low-pressure mercury lamp that emits emission spectrums at wavelengths of 254 nm and 185 nm, a high-pressure mercury lamp that provides a continuous spectrum in the ultraviolet region and visible light, an ultra-high-pressure mercury lamp, a medium-pressure mercury lamp, and the like can be used. The present inventors have confirmed that ultraviolet light having a wavelength of 254 nm emitted from a low-pressure mercury lamp is effective for dechlorination of chlorine-based plastics such as polyvinyl chloride and polyvinylidene chloride. This means that the wavelength is 2
This is because the ultraviolet light of 54 nm is absorbed by the C-Cl bond. It was also confirmed that ultraviolet light having a wavelength of 185 nm generates ozone from oxygen, and also promotes dechlorination by the oxidizing action of the ozone.

In the present invention, the hydrogen chloride gas generated by photodecomposition of the chlorine-based plastic by irradiating ultraviolet rays is sucked out of the system from a vent port, that is, a gas exhaust port provided at the opening. It is composed of Ultraviolet rays are irradiated in the exhaust space formed in the opening, and the atmosphere of the exhaust space at the time of the irradiation may be any of vacuum decompression, atmospheric pressure, nitrogen gas atmosphere, hydrogen gas atmosphere, and the like.

The illuminance of a low-pressure mercury lamp depends on the distance between the lamp and the irradiation target, that is, the irradiation distance. For this reason, the interval between the lamp and the waste plastic to be irradiated is minimized as long as the low-pressure mercury lamp is not damaged. Also, when the temperature of the low-pressure mercury lamp is high, mercury evaporates and absorbs ultraviolet light having a wavelength of 254 nm,
The irradiation energy decreases. Therefore, in the present invention, the low-pressure mercury lamp is cooled to preferably 100 ° C. or less by the cooling means. As a material of the lamp, synthetic quartz or natural quartz is applied. Natural quartz absorbs a wavelength of 185 nm, whereas synthetic quartz transmits this.

As described above, according to the first aspect of the present invention, in order to achieve the above object, a waste plastic containing a chlorine-based resin such as polyvinyl chloride or polyvinylidene chloride is stirred, mixed, kneaded or the like. Surface renewal operation, stirring,
A resin material containing a small amount of residual chlorine by adding at least one of heating and melting operations such as mixing, kneading, heating, and melting, and performing an ultraviolet irradiation operation, and degassing and removing hydrogen chloride generated by the degassing operation. Is configured to obtain According to a second aspect of the present invention, the surface renewal operation, the heat melting operation, the ultraviolet irradiation operation, and the deaeration operation according to the first aspect are continuously performed by a continuous twin-screw kneader having a predetermined length in the axial direction. As described above, the invention according to claim 3 performs the surface renewal operation, the ultraviolet irradiation operation, and the deaeration operation according to claim 2 by forming a space inside a heating cylinder of a continuous twin-screw kneader. The invention according to claim 4 performs the surface renewal operation, the heat melting operation, the ultraviolet irradiation operation, and the degassing operation according to claim 1 in a batch having a predetermined length in the axial direction. The invention according to claim 5 performs the ultraviolet irradiation operation according to any one of claims 1 to 4 using ultraviolet light emitted from a mercury lamp so that the operation is performed batchwise with a twin screw kneader. As described above, the invention described in claim 6 corresponds to any one of claims 1 to 4. Re of the ultraviolet irradiation procedure described in section, to perform a UV emitted from a low pressure mercury lamp emitting an emission line spectrum in a wavelength 254nm and 185 nm, and the invention of claim 7, claim 1-6
The ultraviolet irradiation operation described in any one of the above items is performed for 5 to 60 minutes, and the temperature of the waste plastic at this time is 100 to 35 minutes.
It is configured to run at 0 ° C. An invention according to claim 8 is an apparatus for dechlorinating waste plastic comprising a continuous twin-screw kneader comprising a cylinder barrel and two screws provided to be driven to rotate in the cylinder barrel. In the vicinity of the upstream end of the cylinder barrel, a material injection hole for waste plastic to be dechlorinated is provided, and at a downstream end, a discharge hole for discharging the dechlorinated melt is provided. An opening having an exhaust hole is provided at a position close to the downstream end, and the opening is provided with an ultraviolet irradiation device for irradiating ultraviolet light to waste plastic to be dechlorinated. . According to a ninth aspect of the present invention, there is provided an apparatus for dechlorinating waste plastic comprising a batch type twin screw kneader comprising a cylinder barrel and two screws provided so as to be rotationally driven in the cylinder barrel. A material injection hole for waste plastic to be dechlorinated is provided near one end of the cylinder barrel, and a discharge hole for discharging the dechlorinated melt is provided from the other end. In addition, an opening having an exhaust hole is provided at a substantially intermediate position thereof, and the opening is provided with an ultraviolet irradiation device for irradiating the waste plastic to be dechlorinated with ultraviolet light. Is done. According to a tenth aspect of the present invention, the ultraviolet irradiating apparatus according to the eighth or ninth aspect removes an ultraviolet lamp, an antifouling glass that protects the ultraviolet lamp, and a substance attached to the antifouling glass.
According to an eleventh aspect of the present invention, the ultraviolet lamp according to the tenth aspect includes a wiper device.
The invention according to claim 12 is such that the low-pressure mercury lamp according to claim 11 is cooled by cooling means so that the low-pressure mercury lamp emits an emission line spectrum in ultraviolet rays of 185 nm and 185 nm. The invention according to claim 13 is the invention according to claim 14, wherein the material of the lamp and the material of the antifouling glass according to any one of claims 10 to 12 are synthetic or natural quartz glass. Are claims 8 to 13
A gas supply hole for supplying a gas such as air, nitrogen gas, hydrogen gas or the like is provided in the opening described in any one of the above items.
The screw of the twin-screw kneader corresponding to the opening described in any one of the above items is constituted by a kneading disk.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a waste plastic dechlorination apparatus according to the present invention will be described.
The dechlorination apparatus according to the first embodiment is constituted by a continuous twin-screw kneader as shown in FIGS. The continuous twin-screw kneader includes a heating cylinder barrel 1 having a predetermined length in the axial direction. And
In this heating cylinder barrel 1, two screws 10, 1
0 ′ is provided so as to be rotationally driven in different directions or in the same direction in a meshing or non-meshing state.
At the left end of the heating cylinder barrel 1 in FIG.
A drive device 2 for rotating the screws 10, 10 'at a predetermined speed is provided. This drive 2
Is composed of a motor, a speed reducer, etc., as is well known in the art, and the output shaft of the speed reducer is mechanically connected to the screw shafts 11, 11 '. On the upstream side of the heating cylinder barrel 1, a material charging hole 4 is formed, and a hopper 5 is attached to the material charging hole 4 with its lower end inserted. Further, a vent port, that is, an opening 6 for irradiating and exhausting ultraviolet rays is opened at a position closer to the downstream side of the heating cylinder barrel 1. And screw shaft 1 is located at the downstream end.
A cylinder head 7 for bearing 1, 11 'is mounted. A plurality of heaters 8, 8,..., Each of which has a controlled heating temperature, are attached to the outer periphery of the heating cylinder barrel 1 and the cylinder head 7 configured as described above. In addition, reference numeral 9 written near the material charging hole 4 indicates a sealing material.

The two screws 10, 10 'are arranged in a material transporting / preheating region T, a melting region Y, a region where photodecomposition or photodecomposition and thermal decomposition are simultaneously performed, from the vicinity of the material input hole 4 to the downstream side. An ultraviolet irradiation area S and an ejection area D are provided. In the present embodiment, the material transport / preheating region T is formed of a full flight screw, and the ultraviolet irradiation region S and the discharge region D are formed of a plurality of sheets of different rotation and outer rotation as shown in FIG. Kneading disc 12,
12 ',... Although the mounting state of the kneading disks 12, 12 ',... In the axial direction is not shown in FIG. 3, the kneading disks 12, 12',... For this reason, the long diameter side of one kneading disk 12 is formed so as to scrape the short diameter side of the other kneading disk 12 '. As a result, the waste plastic is transported downstream while receiving a strong shearing force.

As shown in FIG. 3, the cross-sectional shape of the heating cylinder barrel 1 is rectangular at least on the downstream side, and an opening 6 is formed in the rectangular ceiling. Therefore, an ultraviolet irradiation space, that is, an exhaust space 13 is secured below the opening 6 and above the kneading disks 12, 12 ',. In such a manner that the exhaust space 13 is secured, the ultraviolet irradiation device 20 is
Is provided. As shown best in FIG. 3, a plurality of replacement gas supply holes 14 communicating with the exhaust space 13 are provided on one of the side walls 1 a of the heating cylinder barrel 1 forming the exhaust space 13. 14, ... has been opened. The replacement gas supply holes 14, 14,...
Although not shown in FIG. 4, a gas supply pipe for supplying a replacement gas, such as air, nitrogen gas, or hydrogen gas, to the exhaust space 13 is connected. Incidentally, these replacement gas supply holes 14, 14,... Can be closed with a stopper as required. Further, a plurality of gas exhaust holes 15, 15,... Are formed in the other side wall 1b. These gas exhaust holes 15, 15,...
4, 14,... Are not shown in FIGS. The gas exhaust holes 15, 15, ... are connected to an exhaust device such as a vacuum pump. In addition, cylinder cooling water holes 16 through which cooling water for suppressing a rise in the temperature of the waste plastic being processed passes are provided in both side walls 1a, 1b and bottom wall 1c of the heating cylinder barrel 1 constituting the exhaust space 13. , 16,... Are formed.

In the embodiment shown in FIGS. 1 to 3, the gas exhaust holes 15, 15,... Are formed in the ultraviolet irradiation area S, but the gas exhaust holes 15, 15,. , Etc., these gas exhaust holes 15, 15,... Can also be provided in other regions such as the melting region Y, the material transport / preheating region T, and the like.

In the illustrated embodiment, the ultraviolet irradiation device 20 has a plurality of low-pressure mercury lamps 21, 21,..., And a substantially rectangular shape which protects these low-pressure mercury lamps 21, 21,. Antifouling glass 22 exhibiting
The wiper device 40 includes a wiper device 40 for wiping off deposits attached to the antifouling glass 22. The antifouling glass 22 is made of synthetic quartz glass in the present embodiment. And
As shown in FIGS. 2 and 3, the four sides are placed on a glass support frame 24 disposed around the four sides of the opening 6, and a heat-resistant sealing material 25 is interposed between the four sides. The fixing frame 26 is attached to the glass support frame 24 so as to press the four surroundings. The glass fixing frame 26 is mounted on a lamp mounting plate 27 by a plurality of bolts 28, 28,. On the other hand, the lamp mounting plate 27 is mounted on a frame-shaped bracket 29 disposed around the opening 6 by a plurality of screws 30 reaching the heating cylinder barrel 1. In the present embodiment, four low-pressure mercury lamps 21, 21,... Having a predetermined length in the axial direction are provided above the antifouling glass 22 thus attached. As shown in FIG. 3, a plurality of cooling water flow holes 31 are provided in a lamp mounting plate 27 which is mounted to hold these low-pressure mercury lamps 21, 21,.
Are formed in the axial direction. Each of the low-pressure mercury lamps 21, 21,... Is connected to a lamp power supply device 32 by a power supply line a, a. However, FIG. 3 shows only two power supply lines a, a.

The wiper device 40 includes a glass polishing plate 41 having a predetermined width. The glass polishing plate 41 is located below the antifouling glass 22 as shown in FIG. 2 and is in contact with the lower surface of the antifouling glass 22 at predetermined intervals in a direction perpendicular to the plane of FIG. Is reciprocally driven. More specifically, the glass polishing plate 41 is attached to a support member 42 as shown in FIG. The support member 42 is driven by a driving device in a direction perpendicular to the paper surface as described above in FIG. 2 and in a vertical direction in FIG. In the present embodiment, the driving device includes, for example, one driving member 43 that is driven by a hydraulic cylinder at predetermined time intervals, and extends from both ends of the driving member 43 toward the glass polishing plate 41, and a tip end portion thereof is formed of glass. A pair of rods 4 fixed to the polishing plate 41
5 and 45. These rods 45,
The bearing 45 is slidably supported by bearings 46, 46 and guided by guide holes 47, 47 and is driven in the vertical direction in FIG. Therefore, when the driving member 43 is driven back and forth, the glass polishing plate 41 comes into contact with the lower surface of the antifouling glass 22,
The reciprocating drive causes the deposits attached to the lower surface of the antifouling glass 22 to be scraped off.

Next, the operation of the first embodiment will be described. Note that the dechlorination apparatus according to the present embodiment also includes a control device and can automatically perform the dechlorination treatment. However, for simplicity of description, the dechlorination is performed in a form in which automatic and manual operations are mixed. An example of processing will be described. The heating temperatures of the heaters 8 provided on the outer periphery of the heating cylinder barrel 1 and the cylinder head 7 are set. In addition, the cylinder cooling water holes 16, 1, 2 on both side walls 1 a, 1 b and the bottom wall 1 c of the exhaust space 13 are formed.
6. Set the temperature of the water flowing to. Further, the cooling temperature of the low-pressure mercury lamps 21, 21,... Is set. And 2
The screws 10, 10 'are driven to rotate, and a predetermined amount of waste plastic J containing polyvinyl chloride, polyvinylidene chloride and the like cut into a predetermined size is continuously supplied from the hopper 5. Then, waste plastic J
Is sent from the material transport / preheating area T to the discharge area D, but is melted to some extent in the material transport / preheat area T,
The molten plastic is completely melted in the melting area Y composed of the kneading disks 12, 12 ',..., And is sent to the ultraviolet irradiation area S. Here, ultraviolet rays emitted from the low-pressure mercury lamps 21 are irradiated on the surface of the waste plastic J ′. At this time,
Air, nitrogen gas, and hydrogen gas are supplied to the exhaust space 13 and filled with these gases. Alternatively, the replacement gas supply holes 14, 1
.. Are closed and exhausted from the gas exhaust holes 15, 15,. The chlorine is converted into hydrogen chloride by the photodecomposition action by ultraviolet rays or the photodecomposition action and the thermal decomposition action, and is separated from the waste plastic J ′ in a molten state. The separated hydrogen chloride is exhausted and removed from the gas exhaust holes 15, 15,.
As a result, a low chlorine concentration melt J "is continuously discharged to the outside from the discharge hole 3 of the cylinder head 7. The discharged melt J" is appropriately cooled, and a low chlorine concentration harmless fuel, Used as a blast furnace reducing agent, cement raw material, etc.

In general, the waste plastic J is dechlorinated as described above. Hereinafter, the operation of the continuous twin-screw kneader, the operation of the low-pressure mercury lamps 21, 21,. The operation at the time of changing will be described in more detail. The waste plastic J is subjected to stirring, mixing, melting, kneading and surface renewal actions by a continuous twin screw kneader as follows. That is, as shown in FIG. 5A, the two screws 10, 1
When the 0's are partially engaged with each other and are driven to rotate in different directions, the gap formed by the two screw flights greatly changes and generates a complicated flow. It is kneaded while simultaneously receiving the action. In particular, in the rotor portion, the waste plastic J is subjected to a very strong shearing action in a small gap like a calender roll. In addition, each screw 10, 1
There is an outer circumference where the 0 'extends so as to expand with respect to the open portion, and an inner circumference which narrows as the narrower. When the waste plastic J is transferred from one screw 10 to the other screw 10 ', as shown in FIG. 5C, an eight-shape in which the flow path is turned over is drawn. In one screw 10, the waste plastic J which becomes the groove bottom is replaced with the other screw 10 '.
When it moves to, it comes to be located on the surface layer. As a result, the surface of the waste plastic J 'is irradiated by the surface renewal action, and the inside of the waste plastic J' is also irradiated. The portion where the needing disks 12, 12 ',...
As shown in (a) of FIG.

When the two screws 10, 10 'are partially engaged with each other and are driven to rotate in the same direction, as shown in FIGS. The waste plastic J at the bottom of the groove has a self-cleaning action that is scraped off by the flight of the other screw 10 ′, and thus undergoes a surface renewal action. The portions provided with the needing disks 12, 12 ',... Are also subjected to a surface renewal action as shown in FIG. Also, as the flight moves, the waste plastic J is extruded, but one of the screws 10 also moves at the same speed to form a relief for the waste plastic J, so that the waste plastic J is subjected to distributive mixing rather than strong shearing force. . When the waste plastic J moves from one screw 10 flow path to the other screw 10 'flow path, the flow direction of the waste plastic is changed by 90 degrees at the meshing portion of the two screws 10, 10', so that the split flow and the mixing are performed. repeat. In addition, two screws 1
Even when 0 and 10 'are adjacent to each other in a non-meshed state, the stirring, mixing, melting, kneading and surface renewing actions are performed in substantially the same manner.

In this embodiment, the heating cylinder barrel 1
Are provided with the low-pressure mercury lamps 21, 21,... At the same time, so that both the photodecomposition action and the thermal decomposition action are performed at the same time. I do. Chlorine resins such as polyvinyl chloride and polyvinylidene chloride have a C-Cl bond, and the bond dissociation energy of this C-Cl bond is 326 k.
J / mol. The low-pressure mercury lamps 21, 21,.
A bright line is given to the short wavelengths of 254 nm and 185 nm.
Its radiant energy is 472 nm ultraviolet light.
kJ / mol, that of 185 nm is 647 kJ / mol
It is. The number of photons coming out of the low-pressure mercury lamps 21, 21,...
%, Ultraviolet rays having a wavelength of 185 nm account for 6%. As a result, most of the radiant energy of the low-pressure mercury lamps 21 is ultraviolet light having a wavelength of 254 nm. Although the C-Cl bond absorbs both ultraviolet rays having wavelengths of 254 nm and 185 nm, as described above, the proportion of the ultraviolet rays emitted from the low-pressure mercury lamps 21, 21. Most of the wavelengths absorbed by the Cl bond are 254 nm. From the above, the wavelength 25 emitted from the low-pressure mercury lamps 21, 21,...
The ultraviolet light of 4 nm is absorbed by the C-Cl bond, and is given 427 kJ / mol of radiant energy of 326 kJ / mol or more of the bond dissociation energy.
The bond is weakened and the chlorine dissociates, producing hydrogen chloride.
By exhausting these from the gas exhaust holes 15, 15,..., A melt J ″ having a low chlorine concentration can be obtained.

At this time, oxygen is removed from the exhaust space 13, that is, whether the replacement gas supply holes 14, 14,... Are plugged and the gas is exhausted from the gas exhaust holes 15, 15,. Under an atmosphere replaced with an inert gas such as nitrogen gas, a C = C bond is formed as a result of dechlorination. On the other hand, in the presence of oxygen, oxygen receives ultraviolet rays having a wavelength of 185 nm to become ozone, and the ozone receives ultraviolet rays having a wavelength of 254 nm to become active oxygen, thereby promoting the oxidative decomposition of polyvinyl chloride or polyvinylidene chloride. .
As a result, dechlorination is promoted and a carbonyl group is formed at the same time. On the other hand, in the presence of oxygen, oxygen absorbs ultraviolet light having a wavelength of 254, so that the ultraviolet light having a wavelength of 254 absorbed by a C-Cl bond is reduced. As a result, photolysis in the original sense of the C-Cl bond is performed. May be inhibited. However, in any case, the ultraviolet light having a wavelength of 254 nm promotes the dechlorination of the chlorine-based waste plastic J.

On the other hand, hydrocarbons having a C—H bond, such as CH ₄ , C ₂ H ₂ , C ₂ H ₄ , C ₂ H ₆ , C ₃ H ₈ , absorb only ultraviolet rays having a larger energy and a wavelength of 160 nm. Therefore, ultraviolet rays having a wavelength of 254 nm are transmitted. HCl, transmitted similarly for _{H 2.} Therefore, other resins contained in the waste plastic J and the generated hydrogen chloride HCl do not inhibit the photodecomposition of polyvinyl chloride or the like by ultraviolet rays having a wavelength of 254 nm. This indicates that only the C-Cl bond is selectively cleaved by ultraviolet light having a wavelength of 254 nm, and that polyvinyl chloride and the like are selectively decomposed. That is, a wavelength of 254 nm
By irradiating the ultraviolet rays, it is possible to leave a useful hydrocarbon component as a fuel component despite the fact that chlorine can be decomposed and removed, and the fuel yield can be improved. In addition, many plastics contain light stabilizers, ultraviolet absorbers, excited state inhibitors, light blocking agents, antioxidants, etc., and these additives are mainly used in low-light components contained in sunlight. Although it is effective for energy of ultraviolet light and visible light having a wavelength of 290 to 400 nm, the low-pressure mercury lamps 21 and 2 are effective.
It is useless for ultraviolet light of short wavelength and high energy emitted by 1,. Therefore, even if these additives are added to the waste plastic J, the photolysis can be performed without any trouble by using the low-pressure mercury lamps 21, 21,... Of the present embodiment.

As described above, the waste plastic J charged into the heating cylinder barrel 1 is composed of two screws 1
The mechanical shearing force generated inside the waste plastic J by the rotation of the screw 10, 10 'and the temperature set at 100-350 ° C while being transported in the axial direction through the screw groove by the rotation of 0, 10'. The heat is transferred from the heated cylinder barrel 1 and gradually softened, deformed and melted. At the same time, the waste plastic J is uniformly stirred, mixed, melted, and kneaded by the shearing force applied to the waste plastic J by the rotation of the two screws 10, 10 '. While receiving such an action, the waste plastic J reaches the opening 6 as described above. In the opening 6, the surface of the waste plastic J 'is irradiated with ultraviolet rays from the low-pressure mercury lamps 21, 21,. In this opening 6, that is, in the exhaust space 13, the waste plastic J ′
As shown in FIG. 3, while being irradiated with ultraviolet rays, the surface of the substrate is subjected to actions such as uniform stirring, mixing, melting, and kneading by rotation of the two screws 10, 10 ′. At this time, as described above, the irradiated surface of the waste plastic J 'is subjected to a so-called surface renewal effect of frequently exchanging positions with other parts. As a result, each part of the waste plastic J 'in the opening 6 is uniformly photodegraded, and chlorine in the waste plastic is desorbed by dechlorination and dehydrochlorination to generate hydrogen chloride gas. In this way, the waste plastic J 'is subjected to a photolytic action as well as a thermal decomposition action.

At this time, if the set temperature of the heating cylinder barrel 1 from the material input port 4 to the opening 6 is set to be equal to or higher than the melting point of the waste plastic J,
Is irradiated with ultraviolet rays in the opening 6 in a molten state, and if it is set at a temperature lower than the melting point, it is irradiated with ultraviolet rays in a solid state. If the set temperature of the heating cylinder barrel 1 is equal to or higher than the thermal decomposition temperature of the chlorine-based resin and the time required to reach the opening 6 is long, the waste plastic J
Is subjected to a photolytic action by ultraviolet irradiation while undergoing thermal decomposition at the opening 6. That is, by appropriately selecting the set temperature of the heating cylinder barrel 1, the distance from the material input port 4 to the opening 6, the shape of the two screws 10, 10 ′, and the like, the waste plastic J facing the opening 6 can be obtained. In any state such as a solid state, a molten state, and a solid-melt mixed state, the photodecomposition action or the thermal decomposition action or both actions can be taken.

When the temperature of the waste plastic J supplied from the material input port 4 is set so as to reach the opening 6 after several minutes at 200 ° C. or higher, the temperature of the waste plastic J ′ at each part of the waste plastic J ′ at the opening 6 is increased. Thermal decomposition occurs. As shown in FIG. 10, the hydrogen chloride gas generated by the thermal decomposition in each part diffuses inside the waste plastic J ′ to reach the surface facing the opening 6, and the gas in the exhaust space 13 from the surface. Degassed and removed from the exhaust holes 15, 15,. That is, on the surface of the waste plastic J 'facing the opening 6, the decomposed gas generated by the photodecomposition effect occurring near the surface and the decomposed gas generated by the thermal decomposition effect generated at the deep part are degassed and removed. . This cracked gas contains hydrocarbons, mainly hydrogen chloride. If the temperature of the waste plastic J 'is lowered, the thermal decomposition of hydrocarbons is relatively suppressed, and the selective desorption of chlorine in the vicinity of the light irradiation surface proceeds, so that the amount of hydrocarbons decomposed and volatilized is large. , The residual temperature of chlorine becomes relatively low. That is,
Chlorine can be removed while minimizing the loss due to the decomposition of hydrocarbons as fuel. This makes it possible to reduce the residual chlorine concentration and improve the fuel yield.

When hydrogen chloride is generated deep inside the waste plastic J ', the hydrogen chloride reacts with an inorganic filler such as calcium carbonate contained in the plastic to form an inorganic chlorine compound such as calcium chloride. This compound has a boiling point of 1600 ° C. or higher, and is difficult to remove by thermal decomposition at 300 to 400 ° C. Similarly, since the boiling points of magnesium chloride, sodium chloride, and titanium trichloride generated by reacting with hydrogen chloride are 1412 ° C., 1413 ° C., and 440 ° C., respectively, these chlorine compounds cannot be removed by thermal decomposition. If the chlorine compound remains as described above, chlorine is generated when the waste plastic after the dechlorination treatment is used as a blast furnace reducing agent, a fuel, or a cement raw material, which is not preferable.

On the other hand, as shown in FIG. 11, the hydrogen chloride generated on the surface of the waste plastic J 'by the photolysis is directly exhausted to the outside through the gas exhaust holes 15, 15,. Therefore, the frequency of generation of the above-mentioned inorganic chlorine compound is reduced. Therefore, cooling water is supplied to the cylinder cooling water holes 16, 16,... To reduce the temperature of the waste plastic J ′ to be treated, to suppress thermal decomposition, and to cause photodecomposition on the surface, so that high boiling chlorine such as calcium chloride can be obtained. It is desirable to suppress the formation of compounds.

A small amount of water is contained in the waste plastic J to be treated, and when this is irradiated with ultraviolet rays, hydroxyl radicals are generated. In addition, a small amount of air, that is, oxygen is contained, and when ultraviolet rays are irradiated on this, ozone is generated.
Ozone absorbs ultraviolet light having a wavelength of 254 nm and forms active oxygen. This acts as an oxidizing agent, polyvinyl chloride,
Promotes oxidative degradation of polyvinylidene chloride and the like. That is, when ultraviolet light is irradiated from the opening 6, the C-Cl bond on the irradiation surface of the waste plastic J 'has a wavelength of 254 nm.
, The action of accelerating dechlorination due to oxidative deterioration is added simultaneously with the dechlorination by breaking the C-Cl bond. Thereby, dechlorination is remarkably promoted as compared with the case of only thermal decomposition. Also, a hydrogen donor such as isopropyl alcohol is added to the waste plastic J in advance,
When irradiated with ultraviolet rays, two hydrogens are desorbed, one hydrogen is replaced by chlorine of the chlorine-based resin, and the other hydrogen forms hydrogen chloride with the desorbed chlorine. In this way, dechlorination can be promoted.

In this way, the gases such as hydrogen chloride and hydrocarbons produced as a result of the photolysis and the thermal decomposition are
The gas is exhausted from the exhaust space 13 through gas exhaust holes 15, 15,... By a vacuum pump, a blower, or the like. Organic substances contained in the exhausted gas adhere to the antifouling glass 22, but when the adhered substances absorb ultraviolet rays, they are decomposed and removed to some extent. However, the deposits block the ultraviolet light and hinder the photolytic action of the waste plastic. Therefore, in the present embodiment, the wiper device 40 is appropriately operated to remove the deposit. Ultraviolet rays are radiated in the presence of water on a maintenance work or the like for the adhered substance which is hard to fall even by mechanical wiping of the glass polishing plate 41 of the wiper device 40. Then, the attached matter is decomposed by the generation of hydroxyl radicals and the oxidizing action, and can be easily removed. During the dechlorination treatment as described above, hydrogen chloride and hydrocarbons are generated by the photodecomposition action and the thermal decomposition action, and these are reacted from the organic chlorine-based gas or the waste plastic J ′. The outgoing organochlorine-based gas is exhaust gas 13
Exists in the gas phase. However, since these gases are also irradiated with ultraviolet rays, decomposition and detoxification can be expected together with inorganic chlorine-based gases such as carbon tetrachloride.

Next, a description will be given of a dechlorination apparatus according to a second embodiment of the present invention which is subjected to a batch type dechlorination treatment. The second embodiment also includes a twin-screw kneader as shown in FIGS. The twin-screw kneader includes a heating cylinder barrel 50, and kneading disks 51, 51 ',... Which mesh with each other in the cylinder barrel 50 and are driven to rotate outward and in different directions. In the vicinity of one end of the heating cylinder barrel 50, a material charging hole 53 for charging waste plastic is provided. This material input hole 53 is
It can be closed by the stopper 54 as described in the operation section. At the downstream end of the heating cylinder barrel 50, a cylinder head 55 bearing the screw shafts 52, 52 'is attached. The cylinder head 55 has a discharge hole 5 for taking out the dechlorinated melt.
7 is open in the axial direction. In addition, this discharge hole 57
Can also be closed by a stopper 58.

Above the heating cylinder barrel 50, a vent or opening 60 is formed. The opening 60 is provided with an antifouling glass 61 and an ultraviolet irradiation device 62 including a plurality of low-pressure mercury ranks as described above. Although not shown in FIGS. 7 and 8, a wiper device is also provided as necessary. As shown in FIG. 7B, the heat generation temperature is set around the outer periphery of the heating cylinder barrel 50 thus configured except for the opening 60 and the outer periphery of the cylinder head 55. Are provided. The heating cylinder barrel 50 forming the opening 60
As shown in FIG. 7B, a plurality of replacement gas supply holes 6 opened in the exhaust space 64
, And a plurality of gas exhaust holes 66, 66,... Are similarly formed in the other side wall. A drive device including a motor 67, a speed reducer 68, and the like is attached to an end of the heating cylinder barrel 50, and an output shaft of the drive device is mechanically connected to the screw shafts 52, 52 '.

Needing disks 51, 51 ',...
Is mounted on the screw shafts 52, 52 'so that the kneading disk having a constant cross-section in which the major axis and the minor axis are perpendicular to each other is perpendicular to the left and right, as shown in FIG. ing. For this reason, the long diameter side of one kneading disk 51 scrapes the short diameter side of the other kneading disk 51 '. In the axial direction, the major axis and the minor axis are orthogonal to each other. Therefore, according to the present embodiment, there is no function of transporting waste plastic in the axial direction, and only the functions of mixing, stirring, melting, and kneading are provided.

Next, the operation of the dechlorination apparatus according to the second embodiment will be described. The temperature of the heating cylinder barrel 50 is raised in advance. The discharge hole 57 is closed with a stopper 58.
Then, the screw shafts 52 and 52 ′ are rotationally driven to supply the waste plastic pretreated to a predetermined size from the material input hole 53. The material charging hole 53 is closed with the stopper 54.
Then, the supplied waste plastic is subjected to the mixing, stirring, melting and kneading actions, and becomes molten waste plastic J ′. At this time, ultraviolet rays are irradiated from the ultraviolet irradiation device 62 for a predetermined time. Air, nitrogen gas, hydrogen gas and the like are supplied to the exhaust space 64 from the replacement gas supply holes 65, 65,. Alternatively, the pressure in the exhaust space 64 is reduced. It undergoes the photolytic action or the photolytic action and the thermal decomposition action as described in the first embodiment. Decomposed gas generated from the waste plastic is exhausted from the gas exhaust holes 66, 66,. After a lapse of a predetermined time, the plugs 54 and 58 are removed while rotating the screw shafts 52 and 52 ', and the dechlorinated melt J "is discharged from the discharge hole 57. Hereinafter, the batch processing is performed in the same manner. It is apparent that the same operation and effect as those of the first embodiment can be obtained depending on the mode.

Example 1 A test was carried out with and without irradiation with ultraviolet rays under the following conditions using a batch type dechlorination apparatus as shown in FIGS. Outer diameter of kneading disk: 44 mm Number of rotations of kneading disk: 17 rpm · Atmosphere of exhaust space: air Chlorine concentration of waste plastic before treatment: 23% Set temperature of heated cylinder barrel: 280 ° C, 300 ° C, 320 ° C., 340 ° C., 4 points Low-pressure mercury lamp output: 90 W Illuminance of ultraviolet light having a wavelength of 254 nm: 12 mW / cm ² Distance between the tip of the radius of the needing disk and the low-pressure mercury lamp: 30 mm Ultraviolet irradiation time: 18 minutes, 2 minutes 30 minutes The results of the test by irradiating ultraviolet rays under the above conditions are shown by the solid line in FIG. , And the test result when no ultraviolet light is irradiated is indicated by a chain line. When no ultraviolet light is irradiated, only thermal decomposition is performed, and when irradiation is performed, both thermal decomposition and photolysis are performed. As is clear from FIG. 9A, it can be seen that the residual chlorine concentration is lower when irradiating with ultraviolet light under any conditions. In particular, when irradiation was performed for 18 minutes at a set temperature of the heating cylinder barrel of 280 ° C., the residual chlorine concentration was 1 compared with the case of only thermal decomposition.
It has decreased by 4% from 7% to 13%. 18 at 300 ° C
When irradiated for 2 minutes, it decreases by about 2%, and at 320 ° C for 18 minutes,
It is 1% when irradiated at 340 ° C for 16 minutes, but if the distance between the low-pressure mercury lamp and the waste plastic to be treated, the number of rotations of the screw, the shape of the screw, etc. are properly selected, dechlorination can be performed at lower temperatures. It is assumed that

Example 2 A test was carried out with and without UV irradiation under the following conditions using a dechlorination apparatus comprising a continuous twin screw as shown in FIGS. Outer diameter of kneading disk: 44 mm Number of rotations of kneading disk: 17 rpm · Atmosphere of exhaust space: air Chlorine concentration of waste plastic before treatment: 23% Material transport / preheating area of heated cylinder barrel Set temperature: Change within the range of 160 to 200 ° C Set temperature of the melting area of the heating cylinder barrel: Change within the range of 220 to 250 ° C Set temperature of the ultraviolet irradiation area of the heating cylinder barrel: Change within the range of 250 to 350 ° C Discharge Set temperature of the area: changed within the range of 280 to 350 ° C. Output of low-pressure mercury lamp: 90 W Illuminance of ultraviolet light of wavelength 254 nm: 12 mW / cm ² The distance between the tip of the radius of the needing disk and the low-pressure mercury lamp: 30 mm The residence time in the ultraviolet irradiation region: changed within a range of 10 to 15 minutes. The results of the test under the above conditions are almost the same as those of the first embodiment. Met. That is, the result shown in FIG. 9A was obtained. In addition, when the main is photolysis,
The set temperature of the UV irradiation area of the heating cylinder barrel is 200
It has been found that it is desirable to use a relatively low temperature of ２４０240 ° C. and a relatively high temperature of 280-350 ° C. when performing dechlorination by both photolysis and thermal decomposition.

Comparative Example 1: Without using a twin screw kneader, a waste plastic in a molten state heated to 280 ° C. was stretched to a thickness of about 0.1 mm and irradiated with ultraviolet light under the following conditions: The test was performed when no irradiation was performed. Atmosphere: air Chlorine concentration of waste plastic before treatment: 36.8% Output of low-pressure mercury lamp: 90 W Illuminance of ultraviolet light with wavelength of 254 nm: 12 mW / cm ² Distance between the surface of the waste plastic and the low-pressure mercury lamp: 30 mm UV irradiation time: 15 minutes, twice 30 minutes The results of the above test are shown in FIG. Irradiation with ultraviolet light reduced the residual chlorine concentration by 4% compared to the case of only thermal decomposition. From this, it was found that if the waste plastic is made into a thin film, dechlorination can be performed even in a stationary state without specially adding operations such as mixing and stirring, but it is not industrially easy to stretch it into a thin film. Not
Implementation is not impossible, but there is a cost problem. On the other hand, when the twin-screw kneader was used, it was confirmed that the twin-screw kneader exhibited mixing, stirring, melting, kneading and surface renewal effects, and thus could be industrially dechlorinated. It should be noted that it is apparent that the present invention can also be carried out with a stirring device other than the twin-screw kneader, for example, a stirring device provided with a stirring blade rotated by a motor in a cylinder barrel having a function of replacing the surface of waste plastic to be dechlorinated. .

[0047]

As described above, according to the present invention, surface renewal operations such as stirring, mixing, kneading, and the like, and stirring, mixing, and the like are performed on waste plastics containing a chlorine-based resin such as polyvinyl chloride or polyvinylidene chloride. Since at least one of heating and melting operations such as kneading, heating and melting is performed and an ultraviolet irradiation operation is performed, the waste plastic receives ultraviolet light in a solid state, a molten state or a solid-melt mixed state, and Subject to decomposition or photolysis and thermal decomposition. As a result, an effect peculiar to the present invention can be obtained in that the treatment can be performed at a lower temperature as compared with the case of performing dechlorination by thermal decomposition and can be performed in a shorter time than in the case of performing treatment by photolysis. According to the invention in which the surface renewal operation, the heat melting operation, and the ultraviolet irradiation operation are performed by the twin screw kneader, in addition to the above effects, the surface renewal operation, the heat melting operation, and the like are performed more efficiently, and the dechlorination is performed. The effect is further enhanced. In addition, since it is carried out with a twin-screw kneader, the dechlorination treatment capacity is large. Furthermore, according to the invention in which the ultraviolet irradiation operation is performed with ultraviolet light irradiated from a low-pressure mercury lamp, C-Cl bonds can be selectively decomposed, thereby reducing the residual chlorine concentration and increasing the fuel yield. The effects of improving the performance, suppressing the generation of high boiling point chloride, and suppressing the generation of harmful chlorine gas are added.

[Brief description of the drawings]

FIG. 1 is a side view showing a dechlorination apparatus according to a first embodiment of the present invention in a partial cross section in the axial direction.

FIG. 2 is a side view showing an enlarged part of the vicinity of an ultraviolet irradiation device of the dechlorination device shown in FIG.

FIG. 3 is an enlarged sectional view showing the vicinity of an ultraviolet irradiation device of the dechlorination device shown in FIG.

FIG. 4 is an enlarged plan view of the vicinity of an ultraviolet irradiation device of the dechlorination device shown in FIG. 1, as viewed from below.

FIG. 5 is a view showing the screw engagement state and the behavior of waste plastic of the twin-screw kneader according to the embodiment of the present invention. (D) and (E) are schematic diagrams respectively showing the behavior of the waste plastic during meshing and rotating in the same direction.

FIG. 6 is a view showing the engagement state of a kneading disk and the behavior of waste plastic of the twin-screw kneader according to the embodiment of the present invention. FIG. 4 is a schematic view showing the behavior of the waste plastic during the same rotation step by step.

FIG. 7 is a view showing a dechlorination apparatus according to a second embodiment of the present invention, in which (a) is a side view showing a partial cross section in the axial direction, and (b) is a main part thereof. It is sectional drawing.

FIG. 8 is a plan view showing a dechlorination apparatus according to a second embodiment of the present invention in a partial cross section in the axial direction.

FIG. 9 is a diagram showing the results of Examples and Comparative Examples, (A) showing the results of Examples 1 and 2, and (B) showing the results of the Comparative Example.

FIG. 10 is a diagram schematically showing a dechlorination state of waste plastic by thermal decomposition.

FIG. 11 is a diagram schematically showing a dechlorination state of waste plastic by photolysis.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heating cylinder barrel 6 Opening (vent) 10, 10 'Screw 12, 12' Kneading disk 13
Exhaust space 20 UV irradiation device 21
Low pressure mercury lamp 22 Antifouling glass 40
Wiper device 41 Glass polishing plate 50
Heating cylinder barrel 51, 51 'Kneading disc 62
UV irradiation device 64 Exhaust space

 ──────────────────────────────────────────────────の Continued on the front page (72) Noriaki Hashimoto, Inventor 1-6-1, Funakoshi Minami, Aki-ku, Hiroshima-shi, Hiroshima F-term in Japan Steel Works, Ltd. (reference) 4F301 AA17 AC07 AC17 BA01 BA02 BA03 BC02 BC13 BC26 BE39 CA09 CA24 CA51 4G075 AA37 BA05 CA03 CA33 CA63 EB31 FB06

Claims (15)

[Claims] 1. A surface renewal operation such as stirring, mixing, kneading and the like, and a heat melting operation such as stirring, mixing, kneading, heating, melting, etc., for waste plastics containing chlorine resins such as polyvinyl chloride and polyvinylidene chloride. A method for dechlorinating waste plastics, comprising adding at least one of the above operations and performing an ultraviolet irradiation operation, and degassing and removing hydrogen chloride generated by the degassing operation to obtain a resin material having a low residual chlorine content. 2. A continuous twin screw kneader having a predetermined length in the axial direction, wherein the surface renewal operation, the heat melting operation, the ultraviolet irradiation operation, and the deaeration operation according to claim 1 are continuously performed. How to dechlorinate waste plastic. 3. The method according to claim 2, wherein the surface renewal operation, the ultraviolet irradiation operation, and the deaeration operation are performed at a vent portion where a space is formed inside a heating cylinder of the continuous twin-screw kneader.
How to dechlorinate waste plastic. 4. The method according to claim 1, wherein the surface renewal operation, the heat melting operation, the ultraviolet irradiation operation, and the deaeration operation are performed batchwise by a batch type twin screw kneader having a predetermined length in the axial direction. How to dechlorinate waste plastic. 5. A method for dechlorinating waste plastics, wherein the ultraviolet irradiation operation according to any one of claims 1 to 4 is performed using ultraviolet light emitted from a mercury lamp. 6. A method for dechlorinating waste plastics, wherein the ultraviolet irradiation operation according to any one of claims 1 to 4 is carried out with ultraviolet light emitted from a low-pressure mercury lamp emitting emission lines at wavelengths of 254 nm and 185 nm. . 7. The dechlorination of waste plastics, wherein the ultraviolet irradiation operation according to any one of claims 1 to 6 is performed for 5 to 60 minutes and the temperature of the waste plastics is 100 to 350 ° C. Method. 8. A waste plastic dechlorination device comprising a continuous twin-screw kneader comprising a cylinder barrel and two screws provided so as to be driven to rotate in the cylinder barrel, In the vicinity of the upstream end of the cylinder barrel, a material injection hole for waste plastic to be dechlorinated is provided, and at a downstream end, a discharge hole for discharging the dechlorinated melt is provided, and a downstream end is provided. An opening having an exhaust hole is provided at a position close to the waste plastic, and the opening is provided with an ultraviolet irradiation device for irradiating the waste plastic to be dechlorinated with ultraviolet light. Dechlorination equipment. 9. A waste plastic dechlorination apparatus comprising a batch type twin screw kneader comprising a cylinder barrel and two screws provided so as to be driven to rotate in the cylinder barrel, Near one end of the cylinder barrel, a material injection hole for waste plastic to be dechlorinated is provided, and a discharge hole for discharging the dechlorinated melt is provided from the other end. An opening having an exhaust hole is provided at a substantially intermediate position thereof, and the opening is provided with an ultraviolet irradiation device for irradiating the waste plastic to be dechlorinated with ultraviolet light. Waste plastic dechlorination equipment. 10. An ultraviolet irradiating apparatus according to claim 8, wherein the ultraviolet lamp, an antifouling glass for protecting the ultraviolet lamp, and an adhering substance attached to the antifouling glass are removed.
Waste plastic dechlorination unit consisting of a wiper unit. 11. An apparatus for dechlorinating waste plastic, wherein the ultraviolet lamp according to claim 10 is a low-pressure mercury lamp which emits a bright line spectrum to ultraviolet light having a wavelength of 254 nm and ultraviolet light having a wavelength of 185 nm. 12. The low-pressure mercury lamp according to claim 11,
Waste plastic dechlorination equipment that is cooled by cooling means. 13. An apparatus for dechlorinating waste plastic in which the material of the lamp and the material of the antifouling glass according to claim 10 are synthetic or natural quartz glass. 14. A dechlorination apparatus for waste plastic, wherein a gas supply hole for supplying a gas such as air, nitrogen gas, or hydrogen gas is provided in the opening according to any one of claims 8 to 13. 15. A device for dechlorinating waste plastic comprising a kneading disk, wherein the screw of the twin-screw kneader corresponding to the opening according to claim 8 is a kneading disk.