JP3909587B2 - Waste plastic dechlorination equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to waste plastic recycling technology, and more particularly to a dechlorination treatment apparatus using microwaves of waste plastic containing polyvinyl chloride.
[0002]
[Prior art]
In recent years, recycling technology of waste plastics generated in various industrial fields has been attracting attention. Polyvinyl chloride (hereinafter sometimes abbreviated as PVC) has chlorine in its composition, and therefore has other plastics. On the other hand, there was a difficult problem in recycling to fuel.
[0003]
In other words, polyvinyl chloride contained in waste plastic during plastic recycling has the adverse effect of generating hydrogen chloride during incineration and damaging the incinerator, and mixing of hydrogen chloride in the recovered fuel. It is necessary to perform a pretreatment for separating and removing only the vinyl chloride or dechlorinating the polyvinyl chloride.
[0004]
In general, methods such as a flotation method and a centrifugal separation method are known as prior fractionation methods, but the separation accuracy of polyvinyl chloride is not sufficient. In addition, as a method for dechlorination, a method using a rotary kiln and a method using a twin screw extruder have been developed. All of these methods heat polyvinyl chloride contained in waste plastic (high temperature atmosphere). In order to dechlorinate, it is necessary to heat the entire waste plastic, which has the disadvantage of low energy efficiency and high running cost.
[0005]
Therefore, as a method for improving the drawbacks of the above dechlorination technology, waste plastic containing polyvinyl chloride is dielectrically heated by microwaves, and only polyvinyl chloride is heated, so that chlorine from hydrogen chloride is converted into hydrogen chloride. A novel pretreatment method (see, for example, Patent Document 1) that can remove the above has been disclosed. However, there is no description regarding a specific apparatus configuration for dechlorinating waste plastic by microwave treatment.
[0006]
Similarly, a method for treating organic substances (see, for example, Patent Document 2) that specifically targets waste tires is also disclosed as using dielectric heating by microwaves. This published content also mentions a specific device configuration. However, this equipment is not intended for dechlorination of polyvinyl chloride, and it employs a configuration in which multiple microwave oscillators irradiate and heat microwaves from the top to the bottom of the equipment. Therefore, although the irradiation area is covered by the shielding plate, the microwave irradiation efficiency is not sufficient.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-323005 [Patent Document 2]
US Pat. No. 5,084,141 Specification
[Problems to be solved by the present invention]
The present invention has been completed as a result of diligent research to solve such problems, and it is possible to remove polyvinyl chloride from waste plastics by maximizing the irradiation energy of microwaves to the waste plastics. An object of the present invention is to provide a waste plastic continuous dechlorination apparatus capable of efficiently realizing chlorine.
[0009]
[Means for Solving the Problems]
The gist of the present invention is specifically a waste plastic dechlorination apparatus for dechlorinating polyvinyl chloride by dielectrically heating the waste plastic containing polyvinyl chloride as described in claim 1. A process container which can be sealed, a waste plastic supply port provided at one end of the process container, a waste plastic discharge port provided at the other end of the process container, and the supply provided inside the process container A conveying device disposed between the mouth and the discharge port, and connected to a microwave oscillator and disposed across the conveying device, and having a passage port for the conveying device on each side surface. A plurality of waveguides continuously provided in the length direction of the transfer device, an inert gas supply pipe connected to an inert gas source and attached to the processing container, an exhaust device connected to the processing container The A gas pipe, lying in the waste plastic dechlorination apparatus, characterized in comprising a.
Furthermore, in the present invention, as described in claim 2, in the waste plastic dechlorination apparatus having the above characteristics, at least one of the plurality of waveguides connected to the microwave oscillator is provided. It is preferable that the flowing microwave has a phase difference with the microwave flowing through another waveguide.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail focusing on embodiments of the apparatus.
FIG. 1 shows a schematic side view of a waste plastic dechlorination apparatus according to the present invention, and 1 shows a processing container. The processing container 1 has a substantially rectangular parallelepiped shape, and a supply port 23 for supplying the waste plastic 3 is provided at an upper portion of one end (left end in the figure). Further, the other end (right end in the figure) of the processing container 1 is provided with a discharge port 24 for discharging the processed waste plastic 3. Two shutter valves 25 and 26 for sealing the inside of the processing container 1 are installed in the vicinity of the supply port 23 and the discharge port 24, respectively. In addition, a belt conveyor 4 for continuously conveying the waste plastic 3 along the length of the processing container 1 from directly below the supply port 23 to between the discharge ports 24 (claims). Is provided.
[0011]
In the region from the center of the processing container 1 to the discharge port 24 side, there are three heating chambers 30 for covering the upper part of the belt conveyor 4 with a heating chamber 30 for dielectric heating of the waste plastic 3 by microwaves. It is connected to. As shown in the plan view of this portion shown in FIG. 2, the heating chamber 30 is formed by three horizontal and horizontal type waveguide processing units 2b arranged in an orthogonal state across the belt conveyor 4. Yes. Each waveguide processing unit 2b is connected to the microwave oscillator 27 via a waveguide connecting unit 2a provided vertically. Here, although not shown, the connection between the three waveguide connecting portions 2a and the corresponding microwave oscillator 27 is to add a phase difference (for example, 60 degrees each) to the microwaves flowing through each waveguide. The respective connection positions are shifted from each other. Reference numeral 28 denotes a space of the inlet side portion of the waveguide processing section 2b located on the supply port side, a space of the outlet side portion of the waveguide processing section 2b located on the outlet side, and between the waveguide processing sections 2b. It is the sealing body provided so that each space might be covered.
[0012]
Further, the structure of these waveguide processing portions 2b is a box having a rectangular cross section with an aspect ratio of about 1: 2, as shown in the partial sectional perspective view of FIG. A rectangular passage port 31 serving as a passage for the conveyor belt portion 4a is formed on the surface so that the waste plastic 3 on the conveyor belt can pass through the heating chamber 30 continuously. The waveguide processing section 2b has its tip (lower end in FIG. 2) closed with a flat plate or the like (note that the end is cut in FIG. 3 for easy understanding of the internal structure).
[0013]
Reference numeral 8 denotes an inert gas source for supplying an inert gas such as argon or nitrogen to the entire interior of the heating chamber 30 and the processing container 1 via the inert gas supply pipe 6 and the inert gas branch pipe 6a. It is connected to the waveguide connecting part 2a. The inert gas supply pipe 6 and the inert gas branch pipe 6a are provided with a valve 7 and a valve 7a.
[0014]
Further, an exhaust gas pipe 9 for discharging exhaust gas generated by the heat treatment of the waste plastic 3 is provided at the upper part on the discharge port 24 side of the processing container 1, and the exhaust gas pipe 9 has a filter 10 for removing organic substances. To the hydrogen chloride removal tower 12. Below the hydrogen chloride removing tower 12, an alkali tank 17 in which an alkali solution 18 such as a sodium hydroxide solution is stored is installed. An alkali spray nozzle 11 for spraying the alkaline solution 18 to the rising exhaust gas is provided above the hydrogen chloride removal tower 12. The alkali spray nozzle 11 is alkalinized by an alkali supply pipe 36. It is connected to the tank 17. Reference numeral 16 denotes a pump for pumping up the alkaline solution 18.
[0015]
13 is an exhaust gas pipe for guiding the exhaust gas treated in the hydrogen chloride removal tower 12 to the outside of the system, and a filter 14 for removing harmful components such as a small amount of hydrogen chloride remaining in the exhaust gas is attached along the way. ing. In addition, a vacuum pump 15 (exhaust device referred to in the claims) is installed at an end of the exhaust gas pipe 13 for sucking exhaust gas and / or reducing the pressure inside the processing container 1. Reference numeral 35 denotes a bypass pipe provided to connect the inlet side of the exhaust gas pipe 9 and the outlet side of the filter 14 of the exhaust gas pipe 13. Reference numerals 37, 38, and 39 denote valves provided between the bypass branch portion of the exhaust gas pipe 9 and the filter 10, on the bypass pipe 35, and on the outlet side of the filter 10 of the exhaust gas pipe 13.
[0016]
Next, waste plastic processing and operation methods using this apparatus will be described. The
First, the shutter valves 25 and 26 are closed, the inside of the processing container 1 is sealed, the valves 37 and 39 are closed and the valve 38 is opened, and then the vacuum pump 15 is operated without passing through the hydrogen chloride removal tower. The inside of the processing container 1 is evacuated through the exhaust gas pipe 9 and the bypass pipe 10.
[0017]
Next, after the system is evacuated, the valves 7 and 7a are opened, and the inert gas is supplied from the inert gas source 8 through the inert gas supply pipe 6 and the inert gas branch pipe 6a. 2a is supplied to the interior of the processing vessel 1 through the heating chamber 30 of the waveguide processing section 2b and the passage port 31 of the waveguide processing section 2b.
[0018]
Thereafter, the valves 37 and 39 are opened and the valve 38 is closed, and the line on the vacuum pump side is switched from the bypass to the line on the hydrogen chloride removal tower side.
[0019]
Next, after adjusting the pressure inside the apparatus to a predetermined pressure, the operation of the belt conveyor 4 is started, while the microwave oscillator 27 is turned on and the waveguide processing unit 2b is connected via the waveguide connecting unit 2a. A microwave is introduced into the heating chamber 30.
[0020]
Next, the waste plastic 3 is continuously and quantitatively supplied from the supply port 23 while preventing air from entering the processing container 1 by opening and closing the two shutter valves 25 at the entrance. The supplied waste plastic is placed on the belt conveyor 4, flows on the conveyor, is subjected to microwave irradiation in the process of sequentially passing through the three heating chambers 30, is dielectrically heated, and the PVC in the waste plastic is removed. Chlorinated. At this time, the pump 16 is simultaneously operated to supply the alkali solution in the alkali tank 18 to the alkali spray nozzle 11 in the hydrogen chloride removing tower 12 and start spraying to the exhaust gas.
[0021]
The dechlorinated waste plastic 3 is discharged to the outside through the outlet port 24 while maintaining the airtightness in the processing container 1 through the outlet shutter valve 26.
[0022]
The exhaust gas containing hydrogen chloride generated in the dechlorination process is guided to the hydrogen chloride removal tower 12 after the organic content is removed by the filter 10 attached to the exhaust gas pipe 9. The solution is sprinkled and hydrogen chloride is removed. The exhaust gas from which hydrogen chloride has been removed is recovered from the upper part of the hydrogen chloride removal tower 12 to the exhaust gas pipe 13, further removes traces of harmful components such as hydrogen chloride by the filter 14, and finally is purified to a vacuum pump 15. Go out through.
[0023]
In this way, when the processing of the waste plastic is finished, the power source of the microwave oscillator is stopped, the belt conveyor 4 is stopped, and the operation of the hydrogen chloride removing tower 12 and the like is also stopped. Then, the exhaust gas remaining in the apparatus system is sucked by the vacuum pump 15, and then the inside of the system is returned to normal pressure using an inert gas to prepare for the next processing.
[0024]
Next, a characteristic configuration and operation of the apparatus will be described.
First, in this apparatus, the waveguide is directly used as a heating chamber. That is, the inside of the waveguide processing section 2b is a heating chamber 30, and the end of this waveguide processing section is closed, and an opening other than the passage port 31 of the belt section is provided. There is no. As a result, microwave attenuation and leakage to the outside are extremely small, and the irradiation efficiency is high. Therefore, dielectric heating of the waste plastic is extremely effectively performed. Since the waveguide processing unit 2b has a closed end, the microwave introduced into the waveguide processing unit 2b returns as a reflected wave. I can expect.
[0025]
Secondly, in the present apparatus, the waveguide processing section 2b having the passage ports 31 provided on both side surfaces thereof has a horizontal structure that crosses the belt conveyor 4 so as to be orthogonal. Accordingly, all waste plastics placed thereon can be continuously dielectrically heated without hindering the movement of the belt conveyor 4.
[0026]
Thirdly, in the present apparatus, a plurality of waveguides, that is, the waveguide processing portions 2b are continuously provided along the length direction of the belt conveyor 4. In this way, even when dielectric heating is insufficient in the heating chamber 30 of one wave tube processing unit 2b, dechlorination can be reliably performed by the second and subsequent dielectric heating. Productivity in continuous processing utilizing the conveyor 4 can be increased more effectively.
[0027]
Fourthly, in this apparatus, when the plurality of waveguides are connected, the microwave flowing through at least one waveguide is connected to the microwave oscillator, and the microwave flowing through the other waveguide is compared with the microwave flowing through the other waveguide. This is a point configured to have a phase difference (claim 2). For example, the connection positions of the three waveguide connecting portions 2a and the corresponding microwave oscillators 27 are shifted from each other. By doing so, the phases of the microwaves sent from the microwave oscillator 27 to the respective waveguide processing units 2b, that is, the respective heating chambers 30 via the respective waveguide connecting portions 2a are shifted. By irradiating the microwaves having such different phases, it is possible to uniformly heat the waste plastic as a whole. In this case, it is not always necessary that the plurality of waveguides have different phases, as long as the microwave flowing through at least one waveguide has a phase difference from that flowing through the other. It ’s good.
[0028]
In the above description of the present invention, the waste plastic to be dechlorinated has been described centering on the one containing polyvinyl chloride. However, the present invention is also applicable to the case where other plastics containing chlorine such as vinylidene chloride are contained. The invention device can be applied to the same effect.
[0029]
【The invention's effect】
As described above, according to the present invention, it is possible to give the microwave irradiation energy to the waste plastic as much as possible. Therefore, it is possible to perform dechlorination by dielectric heating extremely efficiently and to achieve high productivity. Therefore, the present invention should be an invention with excellent industrial contribution and value in this technical field.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing an embodiment of a waste plastic dechlorination apparatus according to the present invention.
FIG. 2 is a partial plan view of the waste plastic dechlorination apparatus according to the present invention in the same embodiment.
FIG. 3 is a partial cross-sectional perspective view in the same embodiment of the waste plastic dechlorination apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1: Processing container 2a: Waveguide connection part 2b: Waveguide processing part 3: Waste plastic 4: Belt conveyor (conveyance apparatus) 8 Inert gas source 6: Inert gas supply pipe 9: Exhaust gas pipe 23: Supply port 24 outlet 27: microwave oscillator 30: heating chamber 31: passage port

Claims (2)

In a waste plastic dechlorination treatment apparatus for dechlorinating polyvinyl chloride by dielectrically heating waste plastic containing polyvinyl chloride in a waste plastic dechlorination treatment apparatus, and a waste plastic provided at one end of the treatment container A supply port, a waste plastic discharge port provided at the other end of the processing container, a transfer device provided between the supply port and the discharge port inside the processing container, and a microwave oscillator A plurality of waveguides that are connected and arranged across the conveying device and that have passage ports of the conveying device on both side surfaces of the waveguides and that are connected in the length direction of the conveying device; A waste plastic dechlorination comprising: an inert gas supply pipe connected to a gas source and attached to the processing container; and an exhaust gas pipe connected to an exhaust device and attached to the processing container. Management apparatus. Among the plurality of waveguides connected to the microwave oscillator, the microwave flowing through at least one waveguide has a phase difference with the microwave flowing through the other waveguide. The waste plastic dechlorination processing apparatus according to claim 1.

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