JP2009155388A - Decomposition apparatus for plastic and decomposition method for plastic using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decomposition apparatus for plastics capable of reliably and easily cleaning and removing a solid content adhering within a safety valve duct and to provide a decomposition method for plastics using the apparatus. <P>SOLUTION: In the decomposition apparatus 1 for plastics, plastics 30 and a dispersion medium 31 of the plastics are supplied into a reaction chamber 2, and the dispersion medium 31 in the reaction chamber 2 is rendered into a sub-critical or super-critical state to decompose the plastics 30. The apparatus is equipped with a cleaning device for cleaning the inside of a safety valve duct 4 that connects the reaction chamber 2 and a safety valve 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plastic decomposing apparatus and a plastic decomposing method using the same.

  In general, reinforced plastics represented by FRP (fiber reinforced plastics) contain inorganic powders such as calcium carbonate and aluminum hydroxide, and inorganic fibers such as glass fibers. Conventionally, it has been studied to decompose plastic molding waste made of FRP or the like at high temperature and high pressure, recover these inorganic powder, inorganic fiber, and decomposed organic matter from the decomposition solution, and reuse the recovered material. ing.

  For example, a technique for separating and recovering glass fibers by contacting and reacting FRP with subcritical water or supercritical water has been proposed (see Patent Document 1). In this technology, glass fiber is detached from plastic by decomposing plastic into monomers and oligomers using subcritical water or supercritical water as a dispersion medium, and then a mixture of decomposed organic monomers and oligomers and glass fibers is removed. By filtering, the glass fiber is separated and collected as a filtration residue.

As described above, in the technology for decomposing plastics using subcritical water or supercritical water as a dispersion medium, generally, a reaction kettle having a predetermined pressure resistance is used because subcritical water or supercritical water is high temperature and high pressure. A safety valve is connected to the reaction kettle through the safety valve line to prevent the reaction kettle from being damaged due to an excessive increase in internal pressure.
Japanese Patent Laid-Open No. 10-087872

  However, FRP generally contains inorganic powders such as calcium carbonate and aluminum hydroxide in addition to inorganic fibers such as glass fibers as an inorganic substance, and this is stirred with subcritical water or supercritical water. When the decomposition treatment is performed, droplets or bubbles containing inorganic substances may enter the safety valve line connecting the reaction kettle and the safety valve, and solid matter may adhere to the safety valve line. If solid matter adheres to the safety valve pipeline, there is a possibility of clogging. Therefore, sufficient safety cannot be ensured.To prevent clogging, the safety valve pipeline must be cleaned again during non-operation. In other words, there is a problem that complicated work is required.

  The present invention has been made in view of the circumstances as described above, and a plastic decomposing apparatus capable of reliably and easily washing and removing the solid content adhering to the safety valve pipe line and the plastic decomposing using the same. It is an object to provide a processing method.

  The present invention is characterized by the following in order to solve the above problems.

  First, the plastic decomposing apparatus of the present invention supplies a plastic and its dispersion medium into a reaction vessel, and decomposes the plastic with the dispersion medium in the reaction vessel in a subcritical or supercritical state. A cleaning device for cleaning the inside of the safety valve line connecting the reaction kettle and the safety valve, which is disposed in the middle of the safety valve pipe connecting the reaction kettle and the safety valve. To do.

  Secondly, in the first plastic decomposing apparatus, the cleaning apparatus is configured so that the reaction kettle is connected from the safety valve line during the plastic decomposing process or when the plastic and the dispersion medium are supplied into the reaction kettle before the decomposing process. It has a mechanism for allowing the dispersion medium to flow down inside.

  Third, in the first or second plastic decomposing apparatus, the cleaning apparatus is a condenser connected to a safety valve line.

  Fourth, in the first or second plastic decomposing apparatus, the cleaning apparatus is provided in the middle of the safety valve pipe, and at least a dispersion medium for plastic decomposing treatment in the reaction kettle through the safety valve pipe. It is an injection port for injecting a part.

  Fifth, in the plastic decomposition method of the present invention, the plastic containing inorganic powder and / or inorganic fiber and the dispersion medium thereof are supplied into the reaction kettle in the third plastic decomposition apparatus, and the reaction is performed. The dispersion medium in the kettle is subcritical or supercritical, and the plastic is decomposed. At the time of the decomposition, the steam or fluid introduced from the reaction kettle through the safety valve line to the condenser is cooled and condensed. The inside of the safety valve line is washed by returning it to the reaction kettle through the safety valve line as a liquid.

  Sixth, in the plastic decomposition method of the present invention, a plastic containing inorganic powder and / or inorganic fibers and a dispersion medium thereof are supplied into the reaction kettle in the fourth plastic decomposition apparatus, At the time of supplying the dispersion medium, at least a part of the dispersion medium is supplied into the reaction kettle through the safety valve line from the inlet, and then the plastic is decomposed by setting the dispersion medium in the reaction kettle to a subcritical or supercritical state. It is characterized by performing.

  According to the first aspect of the present invention, the cleaning device is disposed so as to clean the inside of the safety valve line, so that the solid content such as inorganic powder and inorganic fibers adhering to the safety valve line during the decomposition process is removed. It can be easily washed and removed, thereby preventing the safety valve line from being blocked by the solid content.

  According to the second aspect of the invention, at the time of the plastic decomposition process, or at the time of supplying the plastic and the dispersion medium into the reaction vessel before the decomposition process, the dispersion medium is simultaneously introduced into the reaction vessel from the safety valve line by the cleaning device. By letting it flow down, in addition to the effect of the first aspect of the present invention, it is possible to reliably and easily wash and remove the solid content adhering to the safety valve pipe line.

  According to the third aspect of the invention, when the plastic is decomposed, steam or fluid is introduced into the condenser from the reaction vessel through the safety valve line, but the steam or fluid introduced into the condenser is cooled and condensed. Is returned to the reaction kettle through the safety valve line. Therefore, in addition to the effects of the first and second inventions described above, it is possible to efficiently wash and remove solid contents such as inorganic powder and inorganic fibers adhering to the safety valve pipeline by the condensate flowing down the safety valve pipeline. it can. As a result, it is possible to effectively prevent clogging of the safety valve line due to the solid content, and to improve the safety of the reaction kettle. In addition, since it is not necessary to clean the inside of the safety valve line again, it is possible to save labor for washing.

  According to the fourth aspect of the invention, when supplying the plastic and its dispersion medium into the reaction kettle, at least a part of the dispersion medium required for the decomposition treatment is fed from the inlet into the reaction kettle through the safety valve line. As a result, the solid content adhering to the safety valve line during the plastic decomposition process in the previous batch can be washed away into the reaction kettle. Therefore, in addition to the effects of the first and second inventions, it is possible to efficiently wash and remove solid content such as inorganic powder and inorganic fibers adhering to the safety valve pipe by the dispersion medium flowing down the safety valve pipe. it can. As a result, it is possible to effectively prevent clogging of the safety valve line due to the solid content, and to improve the safety of the reaction kettle. In addition, since it is not necessary to clean the inside of the safety valve line again, it is possible to save labor for washing.

  According to the fifth aspect of the present invention, solid contents such as inorganic powder and inorganic fibers adhering to the safety valve pipe can be efficiently washed and removed by the condensate flowing down the safety valve pipe. As a result, it is possible to effectively prevent clogging of the safety valve line due to the solid content, and to improve the safety of the reaction kettle. In addition, since it is not necessary to clean the inside of the safety valve line again, it is possible to save labor for washing.

  According to the sixth aspect of the present invention, solid content such as inorganic powder and inorganic fibers adhering to the safety valve pipe line can be efficiently washed and removed by the dispersion medium flowing down the safety valve pipe line. As a result, it is possible to effectively prevent clogging of the safety valve line due to the solid content, and to improve the safety of the reaction kettle. In addition, since it is not necessary to clean the inside of the safety valve line again, it is possible to save labor for washing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a plastic disassembling apparatus according to an embodiment of the present invention. The plastic decomposition apparatus 1 includes a cylindrical reaction kettle 2 having pressure resistance, maintains the temperature and pressure at which the dispersion medium 31 in the reaction kettle 2 becomes a subcritical state, and disperses the subcritical state. The granular plastic 30 is decomposed using the medium 31 as a reaction catalyst. In the present embodiment, FRP of unsaturated polyester resin containing inorganic powder such as calcium carbonate and aluminum hydroxide and inorganic fiber such as glass fiber is used as the plastic 30 to be decomposed, and water is used as the dispersion medium 31. Yes.

  A safety valve 3 is connected to the upper portion of the reaction kettle 2 via a safety valve line 4 constituted by piping. The safety valve 3 is a valve having a safety mechanism for preventing the reaction kettle 2 from being damaged due to an abnormal increase in internal pressure under high temperature and high pressure when the plastic 30 is decomposed. Thus, a so-called spring safety valve in which the fluid in the reaction kettle 2 automatically flows out to keep the internal pressure constant can be used.

  The safety valve line 4 is connected to a condenser 5 (condenser) that functions as a cleaning device in the safety valve line 4 when the plastic 30 is decomposed, and the safety valve is disposed on the opposite side of the condenser 5 from the reaction kettle 2. 3 is connected.

  Further, an inlet 6 for the dispersion medium 31 is provided in the middle of the safety valve line 4, and this inlet 6 is used for supplying the plastic 30 and the dispersion medium 31 into the reaction vessel 2. It becomes part of the supply source and functions as a cleaning device in the safety valve line 4.

  An electric heater 16 for heating the inside of the reaction kettle 2 is provided in the lower part of the outer periphery of the reaction kettle 2, and the reaction kettle 2 further has a temperature control 17 for controlling the temperature in the reaction kettle 2. Is provided. The temperature control 17 controls the electric heater 16 while detecting the temperature in the reaction kettle 2 to perform heating at the optimum temperature.

  The reaction vessel 2 is provided with a stirring device 10 for mixing the plastic 30 and the dispersion medium 31 supplied into the reaction vessel 2. The stirring device 10 includes a rotating shaft 11 that hangs down in the reaction kettle 2 and an agitating blade 12 attached to the rotating shaft 11, and the rotary shaft 11 is driven to rotate by a motor 13 provided on the upper portion of the reaction kettle 2. Thus, the plastic 30 and the dispersion medium 31 in the reaction kettle 2 are stirred and mixed. Further, a plurality of baffle plates 14 are disposed on the inner peripheral portion of the reaction vessel 2, and the baffle plates 14 make the flow of the plastic 30 and the dispersion medium 31 generated by the stirring of the stirring device 10 appropriate. .

  The reaction kettle 2 is provided with a raw material supply port 20, and the raw material supply port 20 is connected to a pretreatment tank (not shown) via an on-off valve 21. In the pretreatment tank, the powdery plastic 30 obtained by pulverizing FRP, the water of the dispersion medium 31 and the alkali are sufficiently stirred and mixed to form a slurry, and this slurry is passed through the raw material supply port 20 by a liquid feed pump. The reaction vessel 2 is supplied.

  The granular material of the plastic 30 to be decomposed prevents sedimentation of the granular material in the reaction vessel 2 and adhesion of the granular material to the inner surface of the reaction vessel 2 at the time of heating. From the viewpoint of improving the reaction efficiency by improving the stirring and mixing properties, it is preferable to grind so that the maximum particle size is 30 mm or less.

  An on-off valve 19 is connected to the upper part of the reaction kettle 2, and after the decomposition reaction is completed, the on-off valve 19 is opened under the monitoring of the pressure control 18, so that the flash vapor of the dispersion medium 31 is turned on and off. The dispersion medium 31 in the reaction kettle 2 is quickly cooled by the heat of vaporization.

  A discharge valve 15 is connected to the bottom of the reaction vessel 2, the plastic 30 is decomposed in the reaction vessel 2, the slurry in the reaction vessel 2 is decompressed and cooled by flash cooling, and then the discharge valve 15 is opened. By doing so, the slurry containing the decomposition product of the plastic 30 is discharged through the discharge valve 15 and is recovered in a slurry recovery tank (not shown).

  Using the plastic disassembling apparatus 1 having the above configuration, the plastic 30 is decomposed as follows. First, as shown in FIG. 1, the plastic 30 and the dispersion medium 31 are put into a pretreatment tank and sufficiently stirred and mixed. The slurry is opened by an opening / closing valve 21 and a raw material supply port 20 by a liquid feed pump. To the reaction kettle 2.

  On the other hand, a part of the dispersion medium 31 is supplied from the inlet 6 into the reaction vessel 2 by opening the on-off valve 7 communicating with the inlet 6 provided in the safety valve line 4. By doing in this way, the solid content adhering in the safety valve line 4 at the time of the decomposition process of the plastic 30 in the previous batch can be washed out in the reaction vessel 2 by the dispersion medium 31 flowing down from the inlet 6.

  Next, the reaction kettle 2 is sealed, and the plastic 30 and the dispersion medium 31 are heated by the electric heater 16 while being stirred by the stirring device 10. Since the reaction kettle 2 is in a sealed state, the internal pressure of the reaction kettle 2 rises while matching the saturated vapor pressure of the liquid temperature.

  And by heating with the electric heater 16 based on control of the temperature control 17, the temperature and pressure which the dispersion medium 31 in the reaction kettle 2 will be in a subcritical state is maintained, and the plastic 30 using this dispersion medium 31 as a reaction catalyst Disassemble.

  For example, in this embodiment, the unsaturated polyester resin is transesterified by adjusting the plastic concentration to 10 to 50% by mass and adjusting the decomposition temperature to 180 to 260 ° C. and maintaining the water in a subcritical state for 30 minutes to 4 hours. And can be hydrolyzed to monomers such as styrene-maleic acid copolymer and polyhydric alcohol. By the decomposition treatment, 80% by mass or more of the plastic 30 becomes a dissolved component.

  During the decomposition process, steam or fluid is introduced into the condenser 5 from the reaction vessel 2 through the safety valve line 4, and the steam or fluid introduced into the condenser 5 is cooled and used as a condensate as a safety valve pipe. It returns to the reaction kettle 2 through the path 4. Therefore, solid content such as inorganic powder and inorganic fibers adhering to the safety valve conduit 4 can be efficiently washed and removed by the condensate flowing down the safety valve conduit 4.

  Thus, after the plastic 30 is decomposed in the reaction vessel 2 using the dispersion medium 31 in the subcritical state as the reaction liquid, the opening / closing valve 19 is opened while adjusting the opening, and the vapor of the dispersion medium 31 is released from the opening / closing valve 19. The pressure in the reaction kettle 2 is reduced. Thereby, the temperature of the dispersion medium 31 in the reaction vessel 2 is lowered by the heat of vaporization of the dispersion medium 31, so that the reaction vessel 2 can be cooled in a shorter time than natural cooling.

  In this way, the dispersion medium 31 in the reaction kettle 2 is cooled, and when the pressure in the reaction kettle 2 is at or near normal pressure, the discharge valve 15 is opened, and the slurry containing the decomposition product of the plastic 30 is removed. The product is discharged from the reaction kettle 2 and collected in a slurry collection tank (not shown).

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, as the plastic 30 to be decomposed, various thermosetting resins can be used, and as the dispersion medium 31 used for the decomposition reaction, water mixed with other components, alcohol, or the like may be used. The decomposition reaction by the dispersion medium 31 may be performed with the dispersion medium 31 in a supercritical state.

  According to circumstances, the plastic 30 and the dispersion medium 31 may be supplied into the reaction vessel 2 separately without using the above-described pretreatment tank. Good.

  In the present specification, “subcritical water” means that the temperature is below the critical point of water (critical temperature 374.4 ° C., critical pressure 22.1 MPa) and the temperature is 140 ° C. or higher, and the pressure at that time In the range of 0.36 MPa (saturated vapor pressure of 140 ° C.) or higher.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all.

  FRP decomposition processing was performed using a plastic decomposition apparatus 1 having the same configuration as in FIG. A slurry raw material was prepared by adding water to FRP pulverized to 10 mm or less, and further adding and mixing sodium hydroxide to a concentration of 0.8M. The slurry raw material was supplied into the reaction vessel 2 from the raw material supply port 20 with the on-off valve 21 opened.

  Thereafter, the on-off valve 21 was closed, and the slurry raw material was heated by the electric heater 16 while the stirring blade 12 of the stirring device 10 was rotated and stirred, and the slurry was operated at 230 ° C. and 2.8 MPa in a subcritical state for 2 hours. At this time, the condenser 5 was not operated.

  After 2 hours, the reaction vessel 2 was naturally cooled, and after the temperature of the reaction vessel 2 reached 100 ° C. or lower, the discharge valve 15 was opened and the decomposition solution was taken out. After cooling to room temperature, the inside of the safety valve line 4 was observed. However, it was soiled with solids.

  Next, in order to perform subcritical decomposition again, the above slurry raw material prepared by adding and mixing FRP, water, and sodium hydroxide was supplied into the reaction vessel 2 in the same manner as described above. However, this time, a part of the water was supplied through the safety valve line 4 from the inlet 6 by opening the on-off valve 7.

  At this time, when the inside of the safety valve pipe line 4 was observed, the adhering solid content was removed.

  The on-off valves 7 and 21 are closed, and the slurry raw material is heated by the electric heater 16 while the stirring blade 12 of the stirring device 10 is rotated and stirred, and the condenser 5 is operated in a subcritical state at 230 ° C. and 2.8 MPa. And run for 2 hours.

  After 2 hours, the reaction vessel 2 was naturally cooled, and after the temperature of the reaction vessel 2 reached 100 ° C. or lower, the discharge valve 15 was opened and the decomposition solution was taken out. After cooling to room temperature, the inside of the safety valve line 4 was observed. However, no stain due to the solid content was observed.

It is the figure which showed schematic structure of the decomposition device of the plastics in one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plastic decomposition device 2 Reactor 3 Safety valve 4 Safety valve line 5 Condenser 6 Inlet 30 Plastic 31 Dispersion medium

Claims (6)

  A plastic decomposing apparatus that supplies plastic and its dispersion medium into the reaction kettle and decomposes the plastic with the dispersion medium in the reaction kettle placed in a subcritical or supercritical state, and connects the reaction kettle and the safety valve. A plastic disassembling apparatus comprising a cleaning device for cleaning the inside of a safety valve pipe disposed in the middle of the safety valve pipe.   The cleaning device is provided with a mechanism for causing the dispersion medium to flow down from the safety valve line into the reaction kettle when the plastic is decomposed or when the plastic and the dispersion medium are supplied into the reaction kettle before the decomposition treatment. The plastic decomposing apparatus according to claim 1.   3. The plastic decomposing apparatus according to claim 1, wherein the cleaning device is a condenser connected to a safety valve line.   The cleaning device is an injection port that is provided in the middle of the safety valve line and injects at least a part of a dispersion medium for plastic decomposition into the reaction kettle through the safety valve line. Or the plastic disassembling apparatus according to 2 above.   A plastic containing inorganic powder and / or inorganic fibers and a dispersion medium thereof are supplied into the reaction kettle in the plastic decomposition apparatus according to claim 3, and the dispersion medium in the reaction kettle is in a subcritical or supercritical state. The steam or fluid introduced into the condenser through the safety valve line from the inside of the reaction kettle is cooled and returned to the reaction kettle through the safety valve line as condensate during the decomposition process. A method for disassembling a plastic, characterized in that the inside of the safety valve line is cleaned by   A plastic containing an inorganic powder and / or inorganic fiber and a dispersion medium thereof are supplied into the reaction vessel in the plastic decomposition apparatus according to claim 4, and at the time of supply of the dispersion medium, at least the dispersion medium is supplied. A method for decomposing a plastic, comprising supplying a part from the inlet to the reaction kettle through a safety valve line and then decomposing the plastic in a subcritical or supercritical state in the reaction kettle.

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