JP2009051967A - Plastic decomposition device and plastic decomposition and recovery method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic decomposition device, capable of appropriately adjusting the opening of an on-off valve so that cooling efficiency can be optimized without being limited by the handling of accompanying discharge of slurry by bumping, and a plastic decomposition and recovery method using the same. <P>SOLUTION: The plastic decomposition device 1 is adapted to put plastic 50 and a liquid 51 into a decomposition tank 2, reduce the fluid 51 in the decomposition tank 2 into a subcritical or supercritical state to decompose the plastic 50, open the on-off valve 22 provided in a vapor discharge pipe 20 connecting with the decomposition tank 2 to discharge vapor, thereby cooling the fluid 51 in the decomposition tank 2. A plurality of bottomed decomposition trays 5 for storing the plastic 50 and the fluid 51 is disposed at vertical intervals within the decomposition tank 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  When the crushed powdered plastic is decomposed by subcritical fluid in the decomposition tank, the mixture becomes a slurry, but the pump for feeding the slurry at high temperature and high pressure is expensive, and the solids cause the parts to be There is a problem with the durability of the pump, such as wear, and it is difficult to discharge all the unreacted solids remaining in the decomposition tank while ensuring the decomposition performance. It is difficult to supply and continuously discharge the decomposition liquid from the decomposition tank.

  In particular, when the plastic to be decomposed is FRP (glass fiber reinforced plastic), inorganic components such as glass fiber and calcium carbonate having a large specific gravity are generated, and it is difficult to discharge these components having high sedimentation properties.

  From such a point, a batch-type decomposition tank is used for the decomposition treatment of a plastic such as FRP with a subcritical fluid (see Patent Document 1). The batch system is a batch process, and the raw material charged into the decomposition tank is taken out from the decomposition tank as it is after the reaction of the batch. The inside of the decomposition tank at the time of the decomposition treatment is in a high temperature and high pressure state in order to bring the fluid into a subcritical state.

Conventionally, in order to cool the decomposition solution in a short time after the decomposition treatment, the decomposition solution temperature is lowered from the subcritical decomposition temperature to the atmospheric pressure or less by flash cooling, and then discharged from the decomposition vessel. Is going. That is, the on-off valve (flush valve) provided in the steam discharge pipe communicating with the decomposition tank is opened to release the flash vapor to a low-pressure system outside the decomposition tank, and the decomposition liquid in the decomposition tank is removed by the heat of vaporization at that time. I'm trying to cool it down.
International Publication No. 2004/041917 Pamphlet

  However, in order to promote the temperature drop due to flash steam, it is necessary to increase the opening of the on-off valve and increase the amount of steam generated. Therefore, the so-called bumping, in which steam is generated from the liquid, occurs, so that the slurry flows into the steam discharge pipe together with the flash steam and is discharged from the on-off valve. If the slurry is entrained in the flash vapor and flows into the steam discharge pipe and is discharged from the on / off valve in this way, the valve body of the on / off valve may be damaged or the steam discharge pipe may be blocked. The opening operation must be performed so as to suppress the accompanying discharge of the slurry, and the operation speed of the on-off valve is limited.

  The present invention has been made in view of the circumstances as described above, and the opening degree of the on-off valve is appropriately set so as to optimize the cooling efficiency without being limited to dealing with the entrainment discharge of slurry due to bumping. It is an object of the present invention to provide a plastic disassembling apparatus that can be adjusted and a plastic disassembling / recovering method using the same.

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

  1stly, the plastic decomposition | disassembly apparatus of this invention throws a plastic and a fluid into a decomposition tank, makes the fluid in a decomposition tank into a subcritical or supercritical state, decomposes | disassembles a plastic, and is a vapor | steam connected to a decomposition tank Opening the on-off valve provided in the discharge pipe to discharge steam, thereby cooling the fluid in the decomposition tank, and the bottomed decomposition that contains the plastic and fluid in the decomposition tank A plurality of dishes are arranged at intervals in the vertical direction.

  Second, the first plastic decomposition apparatus includes a supply means for supplying plastic and fluid to a plurality of decomposition dishes in the decomposition tank.

  Thirdly, the first or second plastic decomposing apparatus is characterized by further comprising discharge means for discharging the liquid containing the decomposition products from a plurality of decomposition dishes in the decomposition tank.

  Fourth, the plastic decomposition / recovery method of the present invention uses any one of the first to third plastic decomposition apparatuses, and puts the plastic and fluid into a plurality of decomposition dishes disposed in the decomposition tank. After disassembling the plastic in a subcritical or supercritical state in the decomposition dish, a gas-liquid interface is formed in each of the plurality of decomposition dishes. The steam is discharged by opening the open / close valve, and after cooling the fluid in the decomposition dish, the liquid containing the decomposition product is discharged to the outside from each of the plurality of decomposition dishes.

  According to the first aspect, since a plurality of decomposition dishes containing plastic and fluid are disposed in the decomposition tank at intervals in the vertical direction, gas-liquid interfaces are formed in the respective decomposition dishes. The area of the liquid interface increases as a whole, which prevents bumping when the on-off valve is opened to discharge the steam and cool the fluid in the cracking tank. Further discharge is prevented. Therefore, the opening degree of the on-off valve can be appropriately adjusted so that the cooling efficiency can be optimized without being limited to dealing with the accompanying discharge of the slurry.

  According to the second aspect of the invention, since the supply means for supplying the plastic and the fluid to the plurality of decomposition dishes in the decomposition tank is provided, in addition to the effect of the first invention, each decomposition dish in the decomposition tank The plastic and fluid are securely contained and a gas-liquid interface is formed in each decomposition dish, and the area of the gas-liquid interface increases as a whole. It is possible to more reliably prevent bumping when cooling.

  According to the third aspect of the invention, since the discharge means for discharging the liquid containing the decomposition products from the plurality of decomposition dishes in the decomposition tank is provided, in addition to the effects of the first and second inventions, the decomposition tank All of the liquid containing the decomposition products stored in the respective decomposition dishes can be discharged to the outside and efficiently recovered.

  According to the fourth aspect of the present invention, a plurality of decomposition dishes containing plastic and fluid are arranged in the decomposition tank at intervals in the vertical direction, and a gas-liquid interface is formed in each decomposition dish, whereby the gas and liquid are formed. With the interface area increased as a whole, the on-off valve was opened to discharge the steam and the fluid in the decomposition tank was cooled, so that bumping due to the lack of the gas-liquid interface was prevented. It is prevented from being discharged from the on-off valve accompanying the flash steam. Therefore, the opening degree of the on-off valve can be appropriately adjusted so that the cooling efficiency can be optimized without being limited to dealing with the accompanying discharge of the slurry.

  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 decomposition tank 2 having a pressure resistance, and maintains a temperature and a pressure at which the fluid 51 in the decomposition tank 2 becomes a subcritical state. The granular plastic 50 is decomposed as a reaction liquid. In the present embodiment, FRP containing an unsaturated polyester resin is used as the plastic 50 to be decomposed, and water is used as the fluid 51.

  The decomposition tank 2 is provided with a pressure detector 15 for detecting the pressure in the decomposition tank 2 at the upper part, and a safety valve 16 is connected to the upper part of the decomposition tank 2. A heating device 14 having a heater and a heating medium jacket is provided at the lower part of the outer periphery of the decomposition tank 2, and a temperature detector 17 is provided in the decomposition tank 2 in a form of being inserted into the decomposition tank 2. . By heating the decomposition tank 2 with the heating device 14 while detecting the temperature in the decomposition tank 2 with the temperature detector 17, the heating device 14 is controlled based on the detected temperature so as to perform heating at the optimum temperature. I have to.

  In the decomposition tank 2, a plurality of, preferably three or more bottomed decomposition dishes 5 are arranged at intervals in the vertical direction. These decomposition dishes 5 contain the plastic 50 and the fluid 51. In this state, the decomposition tank 2 is sealed and heated by the heating device 14, so that the fluid 51 stored in the decomposition dish 5 is brought into a subcritical state. The plastic 50 is decomposed.

  The decomposition tank 2 is provided with a stirring device 10 for mixing the plastic 50 and the fluid 51 accommodated in the decomposition dish 5. The stirring device 10 includes a rotary shaft 12 that hangs down in the decomposition tank 2 and a stirring blade 13 attached to the rotary shaft 12, and the rotary shaft 12 is rotationally driven by a motor 11 provided in the upper part of the decomposition tank 2. As a result, the plastic 50 and the fluid 51 accommodated in the respective decomposition dishes 5 are agitated and mixed.

  A pretreatment tank 41 is connected to the decomposition tank 2 via a raw material supply pipe 40. The pre-treatment tank 41 is charged with the powder 51 obtained by pulverizing the plastic 50 and the fluid 51. The slurry is sufficiently agitated by the agitator 42, and then the slurry is passed through the raw material supply pipe 40 by the liquid feed pump 43. It is made to supply in the decomposition tank 2. FIG.

  The supply means for supplying the slurry to the plurality of decomposition dishes 5 in the decomposition tank 2 can be constituted by the raw material supply pipe 40 and the liquid feed pump 43 outside the decomposition tank 2, but in addition, as a part of the supply means, A pipe that communicates with the raw material supply pipe 40 and supplies the slurry to each decomposition dish 5 may be provided in the decomposition tank 2.

  The granular material of the plastic 50 to be decomposed prevents sedimentation of the granular material in the decomposition dish 5 and adhesion of the granular material to the inner surface of the decomposition dish 5 at the time of heating, and prevents the granular material with respect to the fluid 51 of the granular material. From the viewpoint of improving the mixing efficiency by improving the stirring and mixing properties, it is preferable to grind so that the maximum particle size is 30 mm or less.

  One end of the steam discharge pipe 20 is connected to the upper part of the decomposition tank 2, and the other end of the steam discharge pipe 20 is connected to the condenser 24. An on-off valve 22 (flash valve) is provided in the middle of the steam discharge pipe 20, and by opening the on-off valve 22 after the completion of the decomposition reaction, the flash vapor of the fluid 51 is discharged from the on-off valve 22, The fluid 51 in the decomposition dish 5 is quickly cooled by the heat of vaporization.

  The on-off valve 22 is configured to continuously adjust the degree of opening, that is, the opening degree with respect to the total opening area, and maintain the opening degree at a desired opening degree. The on-off valve 22 and the pressure detector 15 and the temperature detector 17 installed in the decomposition tank 2 are each electrically connected to a control device 60 having a CPU or the like. The opening of the on-off valve 22 is adjusted according to the pressure in the decomposition tank 2 detected by 15 and the temperature in the decomposition tank 2 detected by the temperature detector 17, and thereby the steam discharged from the decomposition tank 2 The amount of is adjusted.

  A slurry discharge pipe 30 is connected to the decomposition tank 2, and the slurry discharge pipe 30 branches and communicates with the respective decomposition dishes 5. After the decomposition treatment, the slurry in the decomposition dish 5 is depressurized and cooled by flash cooling, and then the on-off valve 31 provided in the middle of the slurry discharge pipe 30 is opened, so that the slurry containing the decomposition product of the plastic 50 is Each of the decomposition dishes 5 is discharged through a slurry discharge pipe 30 and recovered in a slurry recovery tank 32.

  The discharge means for discharging the slurry containing decomposition products from the plurality of decomposition dishes 5 in the decomposition tank 2 can be constituted by the branched slurry discharge pipes 30 communicating with the respective decomposition dishes 5. As a part of the means, a slurry delivery pump may be provided in the middle of the slurry discharge pipe 30.

  Using the plastic disassembling apparatus 1 having the above configuration, the plastic 50 is disassembled and collected as follows. First, as shown in FIG. 1, the plastic 50 and the fluid 51 are put into the pretreatment tank 41 and sufficiently stirred and mixed, and this slurry is supplied to the decomposition tank 2 through the raw material supply pipe 40 by the liquid feed pump 43. And accommodated in each disassembly dish 5. Next, the decomposition tank 2 is sealed, and the plastic 50 and the fluid 51 in the decomposition dish 5 are heated by the heating device 14 while being stirred by the stirring device 10. Since the decomposition tank 2 is in a sealed state, the internal pressure of the decomposition tank 2 rises while matching the saturated vapor pressure of the liquid temperature.

  Then, the temperature detector 17 detects the temperature in the decomposition tank 2, and the pressure detector 15 detects the pressure in the decomposition tank 2 while heating with the heating device 14, and heating is performed according to the detected temperature and pressure. By controlling the above, the temperature and pressure at which the fluid 51 in the decomposition dish 5 becomes subcritical are maintained, and the plastic 50 is decomposed using the fluid 51 as a reaction solution. For example, in this embodiment in which FRP containing an unsaturated polyester resin is used as the plastic 50 and water is used as the fluid 51, the plastic concentration is adjusted to 10 to 50% by mass and the decomposition temperature is 180 to 260 ° C. The unsaturated polyester resin can be transesterified by reacting for 30 minutes to 4 hours while maintaining the temperature to be hydrolyzed to a monomer such as a styrene-maleic acid copolymer or a polyhydric alcohol. By the decomposition treatment, 80% by mass or more of the plastic 50 becomes a dissolved component.

  In this way, after the plastic 50 is decomposed in the decomposition tank 2 using the subcritical fluid 51 as the reaction liquid, the control device 60 based on signals from the pressure detector 15 and the temperature detector 17 controls the on-off valve 22. The on-off valve 22 is opened while adjusting the opening, the vapor of the fluid 51 is released from the on-off valve 22, and the pressure in the decomposition tank 2 is reduced. Thereby, since the temperature of the fluid 51 accommodated in the decomposition | disassembly dish 5 falls with the heat of vaporization of the fluid 51, cooling in the decomposition tank 2 can be performed in a shorter time than natural cooling.

  And in this embodiment, since the area of the gas-liquid interface is increased as a whole because the gas-liquid interface is formed in each decomposition dish 5, bumping due to the lack of the gas-liquid interface is prevented, The slurry is prevented from being discharged from the on-off valve 22 along with the flash vapor. Therefore, the adjustment operation of the opening degree of the on-off valve 22 by the control device 60 according to the pressure in the decomposition tank 2 detected by the pressure detector 15 and the temperature in the decomposition tank 2 detected by the temperature detector 17, Without being limited to dealing with bumping, the cooling efficiency of the decomposition tank 2 can be optimized.

  The steam released from the on-off valve 22 is sent to the condenser 24 through the steam discharge pipe 20. A refrigerant such as cooling water is circulated in the condenser 24, and the steam is liquefied by cooling and then recovered in the condensed water recovery tank 25.

  In this way, the fluid 51 in the decomposition dish 5 is cooled, and the on-off valve 31 of the slurry discharge pipe 30 is opened when the pressure in the decomposition tank 2 becomes normal pressure or the vicinity thereof. The slurry containing 50 decomposition products is discharged from each decomposition dish 5 and recovered in the slurry recovery tank 32.

  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 50 to be decomposed, various thermosetting resins can be used, and as the fluid 51 used for the decomposition reaction, water mixed with other components, alcohol, or the like may be used. The decomposition reaction by the fluid 51 may be performed with the fluid 51 in a supercritical state.

  As for the supply of the plastic 50 and the fluid 51 into the decomposition tank 2, the plastic 50 and the fluid 51 may be separately supplied into the decomposition tank 2 without using the pretreatment tank 41. In this case, the supply means for supplying the plastic 50 and the fluid 51 to the plurality of decomposition dishes 5 in the decomposition tank 2 includes a plastic supply pipe and a fluid supply pipe connected to the decomposition tank 2, and a pump provided in these pipes. If necessary, pipes communicating with these pipes may be provided in the decomposition tank 2.

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 apparatus 2 Decomposition tank 5 Decomposition dish 20 Steam discharge piping 22 On-off valve 50 Plastic 51 Fluid

Claims (4)

  The plastic and fluid are put into the decomposition tank, the plastic in the decomposition tank is sub-critical or supercritical and the plastic is decomposed, and then the steam is released by opening the on-off valve provided in the steam discharge pipe communicating with the decomposition tank Is a plastic decomposing apparatus that cools the fluid in the decomposition tank, and a plurality of bottomed decomposition dishes containing plastic and fluid are arranged in the decomposition tank at intervals in the vertical direction. A plastic disassembling apparatus characterized by comprising:   2. The plastic decomposing apparatus according to claim 1, further comprising supply means for supplying plastic and fluid to a plurality of decomposing dishes in the decomposing tank.   The plastic decomposing apparatus according to claim 1 or 2, further comprising discharge means for discharging a liquid containing decomposition products to the outside from a plurality of decomposition dishes in the decomposition tank.   A method for decomposing and recovering plastic using the plastic decomposing apparatus according to any one of claims 1 to 3, wherein plastic and fluid are put into a plurality of decomposing trays arranged in a decomposing tank, and decomposing. An on-off valve provided on the steam discharge pipe that communicates with the decomposition tank with the gas-liquid interface formed in each of the multiple decomposition dishes after the plastic is decomposed with the fluid in the dish in the subcritical or supercritical state A method for decomposing and recovering plastic, comprising: discharging the steam, thereby cooling the fluid in the decomposition dish, and then discharging liquid containing decomposition products from each of the plurality of decomposition dishes.

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