JP4023316B2 - Molten plastic cooling and solidification method and molten plastic cooling and solidification device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molten plastic cooling and solidifying method and a molten plastic cooling and solidifying apparatus that cool and solidify a plastic that has been melted by heat treatment.
[0002]
[Prior art]
In recent years, effective use of waste plastics has been demanded. As one method for effectively using waste plastic, it has been studied to make waste plastic into fine powder and convert it into a solid reducing agent or solid fuel. When waste plastic is made into fine powder, its combustibility is dramatically improved and it can be effectively used as a fuel resource.
[0003]
As a technique for converting waste plastic into solid fuel, there is a method in which waste plastic is directly pulverized by a pulverizer (conventional technique 1) (for example, see Non-Patent Document 1).
In addition, waste plastic discharged from ordinary households (hereinafter, waste plastic discharged from ordinary households is referred to as “one waste plastic”) is mixed with chlorine-containing plastics such as polyvinyl chloride (PVC). Yes. When such a waste plastic is burned as it is as a solid reducing agent or solid fuel for blast furnaces, the chlorine-containing plastic is thermally decomposed to produce hydrogen chloride and the like, and the refractory inner walls of the blast furnace are corroded or produced from the blast furnace. This causes problems such as chlorine mixing in the slag.
[0004]
For this reason, there is a method in which waste plastic is heated and dechlorinated, then cooled and solidified to obtain a solid fuel, and this solid fuel is burned in a furnace to effectively use the waste plastic (conventional technology). 2) (See, for example, Patent Document 1).
Also, after the molten waste plastic is dechlorinated, the molten waste plastic is extruded into a number of cylinders by an extruder and solidified by cooling, and this is sheared to granulate the solid fuel in the granular form (Prior Art 3) (see, for example, Patent Document 2).
[0005]
Furthermore, after the molten waste plastic is dechlorinated, the waste plastic in a molten state is extruded as a rod-shaped body, and this rod-shaped body is cut with a cylindrical rotary cutter and cooled to produce a granular solid fuel. There is a method of granulating (prior art 4) (see, for example, Patent Document 3).
Here, a belt cooler can be mentioned as one of the apparatuses which cool and solidify the waste plastic in a molten state. The belt cooler has a belt that can circulate infinitely, and a molten plastic is supplied and deposited on the belt surface to be conveyed. While the plastic is being transported on the belt surface, the temperature of the plastic is lowered due to heat conduction to the belt, and heat is taken away from the plastic by water or the like sprayed onto the plastic on the belt. In this way, the plastic conveyed to the outlet of the belt cooler is cooled and solidified.
[0006]
The belt cooler can be cooled and solidified without any trouble even if foreign matter is contained in a single waste plastic, and the present inventors have already provided a movable weir above the belt as a device that can operate more efficiently. (Prior Art 5; refer to Patent Document 4) and an apparatus (Conventional Technology 6; refer to Patent Document 5) provided with a rotating member that can rotate along the belt traveling direction.
[0007]
[Non-Patent Document 1]
Murata Katsuhide and Hirano Yoshinao, “Komamasuda Plastic Recycling Technology“ Powdered Fuel ””, Plastics, Japan, Industrial Research Institute, July 1, 1996, Volume 47, Volume 7, p. . 60
[Patent Document 1]
JP-A-11-292976 (pages 2 to 19)
[Patent Document 2]
Japanese Patent Application Laid-Open No. 10-305430 (pages 2 to 3, FIGS. 1 to 4 and 6)
[Patent Document 3]
Japanese Patent Laid-Open No. 10-315236 (pages 2-4, FIGS. 1-9, 11)
[Patent Document 4]
Japanese Patent Application No. 2001-180513
[Patent Document 5]
Japanese Patent Application No. 2001-180514
[0008]
[Problems to be solved by the invention]
However, the method of Prior Art 1 has a disadvantage that even if hard waste plastic is pulverized by a pulverizer, it can only be pulverized to a particle size of about 1 to 2 mm. Moreover, it takes a lot of time and money to directly pulverize waste plastic with a pulverizer, and depending on the shape of the waste plastic, direct pulverization with a pulverizer may be difficult.
[0009]
For example, waste plastics in the form of fibers or films must be melted and solidified and then crushed again by a pulverizer, which complicates the processing steps and increases the processing cost.
In addition, single-use plastics are not stable in composition and have a wide range of fluctuations in average melting point and viscosity. For this reason, in the methods of the prior arts 3 and 4, it is difficult to stably extrude the waste plastic in the molten state. Further, when the foreign material such as metal or glass is contained in the waste plastic, it is often blocked. Causing inconveniences such as reduced operational stability.
[0010]
On the other hand, the belt cooler has a wide tolerance for the average melting point, viscosity fluctuation, and the presence of foreign matter, but in order to perform necessary and sufficient heat removal in the solidification process of the molten plastic placed on the belt. In addition, it is necessary to control the width and thickness of the molten plastic and the rotational speed of the belt to satisfy the necessary heat removal time calculated from the necessary heat removal amount and the size of the apparatus. Although the devices of the prior arts 5 and 6 can cope with a certain amount of supply fluctuation, there is a limit to the fluctuation that can be absorbed when the supply amount fluctuates greatly. That is, the amount of molten plastic supplied to the belt cooler fluctuates, and there is a possibility that when the molten plastic exceeding the calculated value is supplied to the belt cooler, it cannot be sufficiently cooled and solidified. For this reason, it is necessary to determine the performance and size of the belt cooler based on the maximum supply amount of the fluctuation range, and there is a disadvantage that the apparatus size becomes larger than necessary.
[0011]
In particular, when the waste plastic contains a large amount of foreign matter such as bottles and cans, the supply rate of the molten plastic is likely to fluctuate due to blockage and the like, and the belt is liable to be damaged by these foreign matter.
In addition, as shown in Prior Art 2, when one waste plastic is heated and dechlorinated, the processing temperature is generally 200 to 400 ° C., but in order to solidify the molten plastic after processing, the average temperature is 100. It is necessary to cool to ˜120 ° C., and the heat removal capability of the belt cooler is relatively increased. As a result, the apparatus becomes enormous, resulting in problems such as an increase in processing cost and a decrease in operational stability.
[0012]
The present invention has been made in order to solve the above-described problems of the prior art, and the object of the present invention is to change the processing method according to the shape and type of the plastic to be processed, and to solidify by cooling. An object of the present invention is to provide a molten plastic cooling and solidifying method and a molten plastic cooling and solidifying device capable of suppressing the increase in size of the apparatus, improving the operational stability of the cooling and solidifying apparatus, and reducing the processing cost. .
[0013]
[Means for Solving the Problems]
  The present invention adopts the following configuration in order to solve the problem. The invention of claim 1 is a molten plastic cooling and solidifying method in which a plastic in a molten state is taken out of the container, cooled and solidified, and the plastic is supplied from the container to the conveying device in a molten state. ,The temperature of the outlet of the transport device is detected, and the heating and cooling in the transport device are controlled based on the detected temperature, so that the plastic in the molten state in the transport device is Cool within the temperature range that can maintain fluidity,Supplying plastic from the transport device to the belt cooler in a molten state and controlling the amount of plastic supplied from the transport device to the belt cooler to cool and solidify the molten plastic in the belt cooler This is a plastic cooling and solidification method.
[0014]
According to the first aspect of the present invention, the amount of plastic supplied to the belt cooler is controlled, and an amount of plastic that can efficiently exhibit the cooling capacity of the belt cooler can be continuously supplied to the belt cooler. .
Examples of the transport device include a gear pump and a screw feeder.
[0015]
  Also,Claim1According to the inventionThe temperature of the outlet of the conveying device is detected, and heating and cooling in the conveying device are controlled based on the detected temperature, so that the plastic in a molten state in the conveying device can be made fluid. Cool within a maintainable temperature rangeTherefore, the amount of heat removal necessary for cooling and solidifying by the belt cooler is reduced. Therefore, the heat removal capability required for the belt cooler can be reduced. It is also possible to increase the amount of plastic that can be processed without increasing the heat removal capability of the belt cooler.
[0016]
  ContractClaim2The invention of claim1The molten plastic cooling and solidifying method according to claim 1, wherein foreign matter is separated from the molten plastic before the molten plastic is supplied to the belt cooler.
[0017]
  Claim2According to the invention, foreign matter is separated from the molten plastic, so that the foreign matter is prevented from being sent to the conveying device or the belt cooler. Therefore, it is possible to prevent the conveying device from being blocked by foreign matter and the belt of the belt cooler from being damaged by foreign matter.
  Examples of the method for separating foreign substances include a method in which a molten plastic is passed through a strainer, a filter, and the like.
[0018]
  Claim3The invention comprises a container for holding a plastic in a molten state, a transport device that receives a supply of plastic in a molten state from the container, and a belt cooler that receives a supply of plastic in a molten state from the transport device, The transport device includes a supply amount control unit, and the supply amount control unit can control a supply amount of plastic supplied from the transport device to the belt cooler.A heating / cooling device that heats and cools the inside of the conveying device, a thermometer that detects a temperature at an outlet of the conveying device, and the heating device that is based on the temperature detected by the thermometer. A temperature control unit that controls heating and cooling of the heating device, and by controlling heating and cooling in the transport device by the heating and cooling device with the temperature control unit,The plastic is cooled in the conveying device within a temperature range in which the fluidity of the plastic is maintained.RejectThis is a molten plastic cooling and solidifying device.
[0019]
  Claim3According to the invention of claim1Is carried out. For example, a gear pump, a screw feeder, etc. can be mentioned as a conveying apparatus..
[0020]
  ContractClaim4The invention of claim3The molten plastic cooling and solidifying device according to claim 1, wherein the foreign material removes foreign material from the molten plastic between at least one of the container and the transport device and between the transport device and the belt cooler. A molten plastic cooling and solidifying device having a removing device.
  Claim4According to the invention of claim2Is carried out. For example, a strainer, a filter, etc. can be mentioned as a foreign material removal apparatus.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
First, the configuration of the present embodiment will be described with reference to FIG.
As shown in FIG. 1, the molten plastic cooling and solidifying device 10 includes a container 12, a conveying device 24, a heating / cooling device 33, and a belt cooler 48.
[0022]
The container 12 includes a heating device (not shown) that can heat the inside of the container to 200 ° C. to 400 ° C. and a motor-driven stirrer 15, and the plastic 60 that is in a molten state in the container 12 can be dechlorinated. It is configured to be possible.
The plastic 60 supplied to the container 12 may be a so-called virgin plastic or waste plastic. For example, examples of waste plastics include plastics contained in municipal waste, industrial waste, general waste, etc., plastics in municipal waste, packaging container materials, and plastics in industrial waste such as electrical products and automobiles. Mention may be made of plastics produced during the dismantling process. The plastic 60 may be either a thermoplastic resin or a thermosetting resin. For example, polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, polystyrene, polyethylene terephthalate, polycarbonate, Examples thereof include polyamide. Furthermore, the plastics constituting the plastic 60 may be any one of these various plastics, or may be a mixture of two or more.
[0023]
The shape of the plastic 60 before being put into the container 12 may be any of a lump shape, a film shape, a sheet shape, and a fiber shape, and the lump diameter is preferably about 10 cm or less. If the diameter of the lump exceeds about 10 cm, heating and melting in the container 12 takes time, which is not preferable.
The upper space in the container 12 is connected to the hydrochloric acid recovery device 14 so that hydrochloric acid generated by thermal decomposition from the plastic 60 to be dechlorinated can be recovered.
[0024]
A container outlet 16 is formed in the lower part of the container 12, and a pipe 18 is connected from the container outlet 16 to the transport device 24. The container outlet 16 can be opened and closed by a container outlet valve 20, and a strainer 22 is provided as a foreign substance removing device in the pipe 18 downstream of the container outlet 16.
The conveying device 24 includes a screw feeder 26 driven by a motor 30, and the screw feeder 26 has a jacket 28. The rotation number of the motor 30 is controlled by the supply amount control device 32, and the amount of the plastic 60 supplied from the screw feeder 26 to the belt cooler 48 can be controlled by controlling the rotation number of the motor 30. ing.
[0025]
A heat medium pipe 34 that forms a part of the heating / cooling device 33 passes through the jacket 28, and the heat medium flowing through the heat medium pipe 34 can be used to heat and cool the screw feeder 26. ing.
The heating / cooling device 33 is formed of a heat medium pipe 34 and a heat medium heating / cooling device 35. The heat medium pipe 34 connects the heat medium heating / cooling device 35 and the jacket 28 in a loop. The heat medium pipe 34 is filled with a heat medium such as dibenzyltoluene. Switching valves 42 a and 42 b are provided on the heat medium pipes 34 before and after the heat medium heating / cooling device 35, respectively, and switching on the heat medium pipe 34 through which the heat medium is sent from the heat medium heating / cooling device 35 to the jacket 28. A pump 43 and a flow rate control valve 44 are provided on the downstream side of the valve 42a.
[0026]
In the heat medium heating / cooling device 35, there are a boiler 36 and a water-cooled heat exchanger 38 in parallel. The boiler 36 and the heat exchanger 38 are appropriately connected to the heat medium pipe 34 by switching the switching valves 42a and 42b. Connection is possible. When the boiler 36 is connected to the heat medium pipe 34, the heat medium can be heated by the boiler 36, and when the heat exchanger 38 is connected to the heat medium pipe 34, the heat medium is transferred by the heat exchanger 38. The cooling is configured.
[0027]
Further, the belt cooler 48 is located downstream of the screw feeder 26 and receives the supply of plastic 60 from the screw feeder 26. A thermometer 46 is provided at the outlet of the screw feeder 26 so that the temperature Ts of the plastic 60 at the outlet of the screw feeder 26 can be measured.
[0028]
The thermometer 46 is connected to the switching valves 42 a and 42 b and the flow rate control valve 44 via the temperature control unit 40. The temperature controller 40 detects the temperature Ts from the thermometer 46, and switches the switching valves 42a and 42b and the opening degree adjustment signal of the flow control valve 44 according to the detected temperature Ts, respectively. This is transmitted to the valve 44 so that the switching valves 42a and 42b and the flow rate control valve 44 can be controlled.
[0029]
The belt cooler 48 includes a belt 50 that circulates infinitely and a cooling water spraying device 54 that sprays water onto the belt 50. The belt 50 is configured to be rotationally moved by a motor (not shown) and to control the moving speed of the belt 50 by controlling the motor.
A crusher 56 made of a jaw crusher is installed on the downstream side of the belt cooler 48, and the crusher 56 can crush the plastic 60 supplied from the belt cooler 48.
[0030]
This embodiment is configured as described above, and the operation thereof will be described next.
The raw material plastic 60 is continuously supplied into the container 12 and heated and melted, and the stirrer 15 stirs the molten plastic 60. At the same time, dechlorination of the plastic 60 is performed in the container 12. The temperature Tm1 at which the plastic 60 is heated and melted and dechlorinated is higher than the melting point of the plastic 60, and is higher than the temperature Tm2 + ΔTm described later. In order to process one waste plastic, the temperature Tm1 is preferably 200 ° C to 400 ° C, and more preferably 250 ° C to 340 ° C.
[0031]
From the plastic 60 to be dechlorinated, the chlorine contained in the plastic 60 is liberated as hydrochloric acid by thermal decomposition, and this hydrochloric acid is recovered by the hydrochloric acid recovery device 14. The time for heat-melting and dechlorination treatment is preferably 10 minutes to 30 hours. If this time is less than 10 minutes, it is not preferable because temperature management in the container 12 becomes difficult and the dechlorination rate decreases. When this time exceeds 30 hours, the processing efficiency of the molten plastic cooling solidification apparatus 10 falls and it is not preferable. Since the plastic 60 is heated and melted in the container 12, it can be processed regardless of the shape of the plastic 60.
[0032]
After the heating and melting of the plastic 60 is started in the container 12, the heating in the screw feeder 26 is started. Before the molten plastic 60 is supplied from the container 12 to the screw feeder 26, the temperature in the screw feeder 26 is normal temperature Tn, and the temperature Ts at the outlet of the screw feeder 26 is also normal temperature Tn. .
[0033]
The temperature controller 40 determines from the signal from the thermometer 46 that the temperature Ts is normal temperature Tn, sends a switching signal to the switching valves 42a and 42b, connects the boiler 36 to the heat medium pipe 34, and sets the heat exchanger 38. Disconnect from the heat medium pipe 34. The heat medium is heated by the boiler 36, the heated heat medium is sent to the jacket 28 by the pump 43 as a heating heat medium, and the inside of the screw feeder 26 is heated. The heating in the screw feeder 26 is continued until the temperature in the screw feeder 26 reaches a temperature Tm2 that is slightly higher than the melting point of the plastic 60. The heat medium that has lost heat in the jacket 28 is returned to the boiler 36 and heated, and then sent to the jacket 28 by the pump 43 again.
[0034]
When the temperature Ts at the outlet of the screw feeder 26 reaches the temperature Tm2, the temperature control unit 40 adjusts the flow rate of the flow rate control valve 44 to maintain the temperature Ts at the outlet of the screw feeder 26 within the range of temperature Tm2 ± ΔTm. The temperature Tm2−ΔTm is higher than the melting point of the plastic 60.
When the temperature Ts at the outlet of the screw feeder 26 falls within the range of the temperature Tm2 ± ΔTm, the container outlet valve 20 is opened and the molten plastic 60 is allowed to flow into the screw feeder 26. The plastic 60 that has left the container 12 passes through the strainer 22, and foreign substances contained in the plastic 60 are removed by the strainer 22. Therefore, it is prevented that the foreign material in the plastic 60 is clogged in the screw feeder 26, and the stable operation of the molten plastic cooling solidification apparatus 10 is prevented.
[0035]
When the molten plastic 60 enters the screw feeder 26, the motor 30 is controlled by the supply amount control device 32 to rotate at a constant rotational speed, and the plastic 60 is supplied from the screw feeder 26 to the belt cooler 48 at a constant supply amount. Supplied. Since the temperature Ts at the outlet of the screw feeder 26 is within the range of the temperature Tm2 ± ΔTm, the molten state of the plastic 60 is maintained in the screw feeder 26, and the plastic 60 has a fluidity from the screw feeder 26 to the belt. It will be sent to the cooler 48. Therefore, the plastic 60 does not lose fluidity in the screw feeder 26, and the solidified plastic 60 is prevented from being clogged in the screw feeder 26.
[0036]
In addition, the supply amount control device 32 controls the number of rotations of the motor 30 to control the supply amount of the plastic 60 supplied to the downstream belt cooler 48, so that the cooling capacity of the belt cooler 48 can be efficiently exhibited. The plastic 60 is supplied to the belt cooler 48. The control of the rotation speed of the motor 30 by the supply amount control device 32 is preferably such that the fluctuation range of the supply amount of the plastic 60 supplied to the belt cooler 48 becomes ± 20%.
[0037]
When the plastic 60 having the temperature Tm1 enters the screw feeder 26 from the container 12, the temperature in the screw feeder 26 increases due to the heat of the plastic 60, and the temperature Ts at the outlet of the screw feeder 26 also exceeds the temperature Tm2 + ΔTm. When the temperature Ts exceeds the temperature Tm2 + ΔTm, the temperature control unit 40 sends a switching signal to the switching valves 42a and 42b, disconnects the boiler 36 from the heat medium pipe 34, and connects the heat exchanger 38 to the heat medium pipe 34.
[0038]
A plastic 60 having a temperature Tm1 is continuously supplied from the container 12 into the screw feeder 26, and the temperature in the screw feeder 26 is constantly going to exceed the temperature Tm2 + ΔTm by the heat of the plastic 60. On the other hand, the low-temperature heat medium from the heat exchanger 38 is sent to the jacket 28 by the pump 43 as a cooling heat medium, and the heat medium removes heat from the plastic 60 in the screw feeder 26 by the jacket 28, and the screw feeder. The temperature Ts at the outlet 26 is maintained within the range of the temperature Tm2 ± ΔTm. The temperature control unit 40 sends a control signal to the flow control valve 44 to adjust the flow rate of the heat medium according to the amount that the temperature Ts deviates from the temperature Tm2, and the heat amount that the heat medium takes from the plastic 60 in the screw feeder 26. Adjust.
[0039]
The supply amount of the plastic 60 from the screw feeder 26 to the belt cooler 48 is controlled to be constant by the supply amount control device 32, and the moving speed of the belt 50 is also controlled to be constant. It spreads with a certain thickness and width above. Since the foreign material is already separated from the plastic 60 on the belt 50 by the strainer 22, the belt 50 is prevented from being damaged by the foreign material.
[0040]
As the belt 50 moves, water is sprayed from the cooling water spraying device 54 to the plastic 60 on the belt 50. The plastic 60 is deprived of heat by the belt 50 and the sprayed water, and is cooled to below the melting point and solidified.
The plastic 60 supplied to the belt cooler 48 has already been removed of heat in the screw feeder 26 and is only in the range of a temperature Tm2 ± ΔTm that is slightly higher than the melting point of the plastic 60. Thus, the amount of heat removal necessary for solidifying the plastic 60 is less than the amount of heat removal necessary when the plastic 60 in the molten state in the container 12 is directly cooled and solidified. That is, the heat removal capability required in the belt cooler 48 can be reduced to the necessary minimum amount, and the belt cooler 48 can be prevented from increasing in size.
[0041]
The plastic 60 solidified on the belt 50 is supplied to a pulverizer 56 and pulverized to a predetermined particle size. Since the plastic 60 supplied from the belt cooler 48 is cooled and solidified, the plastic 60 having a semi-molten portion is prevented from being supplied to the pulverizer 56. For this reason, it is also possible to prevent the semi-molten plastic 60 from adhering to the pulverizer 56 and preventing stable continuous operation of the molten plastic cooling and solidifying device 10.
[0042]
Next, taking as an example the case where the plastic 60 to be processed by the molten plastic cooling and solidifying apparatus 10 is polyethylene, the relationship between the heat removal amount from the plastic 60 in the screw feeder 26 and the heat removal amount in the belt cooler 48 will be described with reference to FIG. Specific explanation will be given.
The melting point range of polyethylene is 140 ° C. to 150 ° C., and the polyethylene melts when heated to 300 ° C. Thereafter, when the molten polyethylene is cooled to 150 ° C. and the sensible heat Q1 is removed from the polyethylene, the viscosity increases as the temperature decreases, but the fluidity is maintained. Crystallization occurs in the polyethylene as the cooling of the polyethylene proceeds and the temperature drops to 150-140 ° C. Between 150 ° C. and 140 ° C., latent heat of fusion Q2 is removed from the polyethylene. When the temperature becomes 140 ° C. or lower, the polyethylene starts to solidify, and when cooled to 120 ° C., it becomes a uniform solidified body. Between 140 ° C and 120 ° C, sensible heat Q3 is removed from the polyethylene.
[0043]
Therefore, the polyethylene is processed in the molten plastic cooling and solidifying apparatus 10, and the polyethylene is heated and melted at 300 ° C. in the container 12, and is directly melted from the container 12 to the belt cooler 48 without passing through the screw feeder 26. And the temperature of polyethylene supplied from the belt cooler 48 to the pulverizer 56 is cooled to 120 ° C. In this case, the necessary heat removal amount Qt in the belt cooler 48 is Q1 + Q2 + Q3.
[0044]
However, it is not necessary to remove the heat quantity Qt of Q1 + Q2 + Q3 in the belt cooler 48, and a part of the heat quantity Qt can be removed in advance between the belt cooler 48 and the container 12. Between the belt cooler 48 and the container 12, polyethylene can be passed through the screw feeder 26, and a part of the heat quantity Qt can be removed by the screw feeder 26.
[0045]
For example, the polyethylene is cooled to 160 ° C. in advance in the screw feeder 26, the polyethylene at 160 ° C. is supplied to the belt cooler 48, and the polyethylene cooled to 120 ° C. is supplied from the belt cooler 48 to the pulverizer 56. In this case, the heat removal amount Qs in the screw feeder 26 is a value represented by the following formula (1),
Qs = Q1 × (300−160) / (300−150) (1)
The amount of heat Qb removed from the polyethylene in the belt cooler 48 is a value represented by the following equation (2).
[0046]
Qb = Qt−Qs
= Q1 × (160−150) / (300−150) + Q2 + Q3 (2)
Therefore, by pre-cooling the plastic 60 in the screw feeder 26, the heat removal amount in the belt cooler 48 can be greatly reduced, the size of the belt cooler 48 can be reduced, and the processing amount in the belt cooler 48 can be increased. It becomes possible to make it. Thereby, productivity of a solid fuel and a solid reducing material can be improved, and the manufacturing cost can be reduced.
[0047]
Further, the molten plastic cooling and solidifying device 10 can produce a plastic 60 solidified so as to be easily pulverized by a pulverizer 56. The solidified plastic 60 is pulverized by the pulverizer 56 and is finely powdered solid fuel excellent in combustibility. And a solid reducing material can be obtained.
Furthermore, since the plastic 60 is first heated and melted and dechlorinated, a highly safe solid fuel or solid reducing material that does not substantially contain chlorine can be manufactured. By burning such a solid fuel and solid reducing material substantially free of chlorine in a furnace such as a blast furnace, boiler, kiln, cupola, coke oven, etc., the inner wall refractory in the furnace is made of chlorine or a chlorine compound. Prevents chemical erosion.
[0048]
In the present embodiment, the plastic 60 is continuously supplied into the container 12 and continuously operated. Alternatively, the molten plastic cooling and solidifying apparatus 10 can be operated by batch operation.
Further, although the heat medium flowing in the heat medium pipe 34 is dibenzyltoluene, it is needless to say that the heat medium is not limited to dibenzyltoluene. The boiler 36 and the heat exchanger 38 heat and cool different types of heating medium and cooling heat medium, respectively, and switch the switching valve 42 to cause the different types of heat medium to flow through the heat medium pipe 34. Is possible. For example, dibenzyltoluene can be used as the heating medium and water can be used as the cooling medium. However, from the viewpoint of simplifying the operation, maintenance, and the like of the molten plastic cooling and solidifying apparatus 10, it is desirable to use a single type of heat medium as the heating heat medium and the cooling heat medium.
[0050]
Further, although the strainer 22 as a foreign substance removing device is provided downstream of the container outlet valve 20, it is also possible to provide the strainer 22 between the screw feeder 26 and the belt cooler 48 instead of the container outlet valve 20. It is also possible to provide them downstream and at both positions between the screw feeder 26 and the belt cooler 48, respectively. A filter may be installed instead of the strainer 22.
[0051]
The crusher 56 is formed by a jaw crusher. However, the crusher 56 is not limited to the jaw crusher, and the crusher 56 can be formed by a roll crusher, a ball mill, a centrifugal mill or the like.
(Example)
Next, verification tests 1 to 3 and a reference test performed using the molten plastic cooling and solidifying apparatus 10 according to the present embodiment will be described.
[0052]
The molten plastic cooling and solidifying device 10 used in the verification test 1 has the same configuration as that described in the present embodiment, except that the control operation of the switching valves 42a and 42b and the flow rate control valve 44 is manually performed. Have.
The plastic 60 to be treated was a waste plastic of 150 kg which was collected separately in Kanagawa Prefecture, and this plastic 60 was heated and melted at 320 ° C. in a container 12 having an internal volume of 500 liters and subjected to dechlorination treatment for 1 hour. And while maintaining the plastic 60 after the dechlorination process in the container 12 at 320 degreeC, the temperature in the screw feeder 26 was raised to about 320 degreeC with the heat medium which was 340 degreeC with the boiler 36. FIG. Thereafter, the inside of the screw feeder 26 was continuously heated by a heat medium at 340 ° C.
[0053]
And after operating the screw feeder 26, the container outlet valve 20 was opened, and the plastic 60 in the molten state was supplied from the container 12 to the screw feeder 26. The supply amount control device 32 controlled the supply amount of the plastic 60 from the screw feeder 26 to the belt cooler 48 to 50 kg / hour, and continuously supplied the plastic 60 onto the belt 50 of the belt cooler 48. The supply amount of the plastic 60 from the screw feeder 26 and the moving speed of the belt 50 were kept constant, and the thickness of the plastic 60 deposited on the belt 50 was kept at 7 mm. At this time, the average time for cooling the plastic 60 on the belt 50 was 160 seconds. The plastic 60 cooled and solidified on the belt 50 was pulverized as it was by a pulverizer 56 to produce a solid fuel.
[0054]
In the verification test 1, the following results were obtained. The temperature Ts of the plastic 60 at the outlet of the screw feeder 26 was 312 ° C., and the molten plastic 60 could be continuously supplied from the screw feeder 26 to the belt cooler 48. Further, the plastic 60 could be continuously processed and pulverized for 3 hours, and during this time, no problem occurred that hindered the operation of the molten plastic cooling and solidifying device 10.
[0055]
Further, the chlorine concentration contained in the plastic 60 before the treatment was 3.5%, but the chlorine concentration contained in the plastic 60 exiting the belt cooler 48 was reduced to 0.3%. Therefore, it was confirmed that a highly safe solid fuel or solid reducing material substantially free of chlorine can be produced by heating and melting the plastic 60 in the container 12 and performing a dechlorination treatment. The treated waste plastic contained about 70% of polyethylene, polypropylene and polystyrene in total.
[0056]
Next, the verification test 2 will be described. The configuration of the molten plastic cooling and solidifying apparatus 10 used in the verification test 2 was the same as that in the verification test 1. The operating conditions of the molten plastic cooling and solidifying apparatus 10 were the same as the operating conditions in the verification test 1 except for the following points. That is, the supply amount of the plastic 60 from the screw feeder 26 to the belt cooler 48 was set to 100 kg / hour.
[0057]
25 minutes after the supply of the plastic 60 from the screw feeder 26 to the belt cooler 48 is started, the molten plastic 60 adheres to the pulverizing blade of the pulverizer 56, and the subsequent continuous operation of the molten plastic cooling and solidifying device 10 is not possible. It has become possible. At this point, the state of the plastic 60 exiting the belt cooler 48 was examined. As a result, the upper and lower surfaces of the plastic 60 were solidified, but a semi-molten portion over a thickness of 3 mm was present at the center.
[0058]
In the verification test 2, the plastic 60 exiting the belt cooler 48 was partially in a semi-molten state because the supply amount of the plastic 60 on the belt 50 exceeded the cooling capacity of the belt cooler 48. is there. Therefore, it is necessary for the continuous operation of the molten plastic cooling and solidifying device 10 to appropriately adjust and control the supply amount, and the usefulness of the supply amount control device 32 has been confirmed.
[0059]
Next, the verification test 3 will be described. The configuration of the molten plastic cooling and solidifying apparatus 10 used in the verification test 3 was the same as that in the verification test 1. The operating conditions of the molten plastic cooling and solidifying apparatus 10 were the same as the operating conditions in the verification test 1 except for the following points.
That is, after the cooling and solidification of the plastic 60 is started in the belt cooler 48, the switching valves 42a and 42b are switched to disconnect the boiler 36 from the heat medium pipe 34, and the heat exchanger 38 is connected to the heat medium pipe 34. The plastic 60 in the screw feeder 26 is cooled by a heat medium set to 50 ° C. in the heat exchanger 38, the opening degree of the flow rate control valve 44 is adjusted, and 20 minutes after the heat exchanger 38 is switched, the screw feeder 26 The temperature Ts of the plastic 60 at the outlet was stabilized at 230 ° C.
[0060]
As a result of the verification test 3, the molten plastic 60 was continuously supplied from the screw feeder 26 to the belt cooler 48. Further, the plastic 60 could be continuously processed and pulverized for 3 hours, and during this time, no problem occurred that hindered the operation of the molten plastic cooling and solidifying device 10.
Next, the verification test 4 will be described. The configuration of the molten plastic cooling and solidifying apparatus 10 used in the verification test 4 was the same as that in the verification test 1. The operating conditions of the molten plastic cooling and solidifying apparatus 10 were the same as the operating conditions in the verification test 1 except for the following points.
[0061]
That is, after the cooling and solidification of the plastic 60 is started in the belt cooler 48, the switching valves 42a and 42b are switched to disconnect the boiler 36 from the heat medium pipe 34, and the heat exchanger 38 is connected to the heat medium pipe 34. At the same time as switching from the boiler 36 to the heat exchanger 38, the supply amount of the plastic 60 from the screw feeder 26 to the belt cooler 48 was set to 100 kg / hour. The plastic 60 in the screw feeder 26 is cooled by the heat medium cooled to 50 ° C. by the heat exchanger 38, the opening degree of the flow rate control valve 44 is adjusted, and 20 minutes after switching to the heat exchanger 38, the screw feeder The temperature Ts of the plastic 60 at the 26 outlets was stabilized at 260 ° C. Further, the amount of movement of the belt 50 was adjusted to maintain the thickness of the plastic 60 deposited on the belt 50 at 7 mm, and the amount of movement of the belt 50 at this time was maintained. The average time for cooling the plastic 60 on the belt 50 was 80 seconds.
[0062]
As a result of the verification test 4, the plastic 60 in a molten state could be continuously supplied from the screw feeder 26 to the belt cooler 48. Further, the plastic 60 could be continuously processed and pulverized over 1 hour and 30 minutes, and during this time, no problem occurred that hindered the operation of the molten plastic cooling and solidifying apparatus 10.
By comparing the result of the verification test 4 with the result of the verification test 3, the temperature of the plastic 60 is cooled in advance by a heat medium sent from the heat exchanger 38 in the screw feeder 26 to remove heat, and the belt cooler 48 is removed. It was confirmed that the processing capacity of the molten plastic cooling and solidifying device 10 can be improved by reducing the amount of heat removed at.
[0063]
Next, a comparative test conducted for reference will be described. The configuration of the molten plastic cooling and solidifying apparatus 10 used in this reference test was the same as that in the verification test 1 except for the following points (see FIG. 3).
That is, the plastic 60 in a molten state is directly supplied to the belt cooler 48 downstream of the container outlet valve 20, and the strainer 22, screw feeder 26, and heating / cooling device 33 are removed.
[0064]
The heat melting and dechlorination treatment of the plastic 60 in the container 12 was the same as in the verification test 1, and the plastic 60 at 320 ° C. was continuously supplied from the container outlet valve 20 to the belt cooler 48. The container outlet valve 20 was opened and closed intermittently, and the amount of plastic 60 supplied to the belt cooler 48 was adjusted to 50 kg / hour. The plastic 60 was cooled and solidified on the belt 50 of the belt cooler 48, and the plastic 60 solidified by the pulverizer 56 was pulverized.
[0065]
In this comparative test, the thickness of the plastic 60 deposited on the belt 50 varied between 2 and 12 mm, and could not be maintained at a constant thickness of 7 mm. The moving speed of the belt 50 was maintained so that the time for cooling the plastic 60 on the belt 50 was 160 seconds on average.
As a result of the comparative test, while the molten plastic cooling and solidifying device 10 was operated for one hour, the molten plastic 60 adhered to the pulverizing blade of the pulverizer 56 and the molten plastic cooling and solidifying device 10 was not continuously operated. There were three possible situations.
[0066]
When these continuous operations became impossible, the state of the plastic 60 exiting the belt cooler 48 was observed, and the upper and lower surfaces of the plastic 60 were solidified. Existed. In the portion of the plastic 60 having a thickness of 12 mm on the belt 50, the thickness of the semi-molten portion was 4 mm.
[0067]
Therefore, from this comparative test, it was confirmed that the molten plastic cooling and solidifying device 10 cannot be stably operated continuously unless the plastic feeder 60 is supplied to the belt cooler 48 with a constant controlled supply amount by the screw feeder. .
[0068]
【The invention's effect】
Since the present invention is the above-described molten plastic cooling and solidifying method and molten plastic cooling and solidifying device, there is no need to change the processing method depending on the shape of the plastic to be processed, and the cooling and solidifying device that cools and solidifies the molten plastic is large. Therefore, it is possible to provide a molten plastic cooling and solidification method and a molten plastic cooling and solidification device that can improve the operational stability of the cooling and solidification device and can reduce the processing cost.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a molten plastic cooling and solidifying apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a heat removal amount of polyethylene.
FIG. 3 is a configuration diagram of a molten plastic cooling and solidifying apparatus used in a comparative test.
[Explanation of symbols]
10 Melting plastic cooling and solidification equipment
12 containers
14 Hydrochloric acid recovery equipment
15 Stirrer
16 Container outlet
18 Piping
20 Container outlet valve
22 Strainer
24 Conveying device
26 Screw feeder
28 jacket
30 motor
32 Supply amount control device
33 Heating and cooling device
34 Heat medium piping
36 boiler
38 Heat exchanger
40 Temperature controller
42a, 42b switching valve
43 Pump
44 Flow control valve
46 Thermometer
48 belt cooler
50 belts
54 Cooling water spraying device
56 Crusher
60 plastic

Claims (4)

A molten plastic cooling and solidifying method in which a plastic in a molten state in a container is taken out from the container and cooled and solidified.
Supply the plastic from the container in a molten state to the transport device,
The temperature of the outlet of the transport device is detected, and the heating and cooling in the transport device are controlled based on the detected temperature, so that the plastic in the molten state in the transport device is Cool within the temperature range that can maintain fluidity,
While supplying the plastic from the transport device to the belt cooler in a molten state, and controlling the amount of plastic supplied from the transport device to the belt cooler,
A molten plastic cooling and solidifying method, wherein the molten plastic is cooled and solidified in the belt cooler. The molten plastic cooling and solidifying method according to claim 1 , wherein foreign substances are separated from the molten plastic before the molten plastic is supplied to the belt cooler. . A container that holds a plastic in a molten state, a transport device that receives supply of the plastic in a molten state from the container, and a belt cooler that receives supply of the plastic in a molten state from the transport device,
The transport device includes a supply amount control unit, and the supply amount control unit can control the supply amount of plastic supplied from the transport device to the belt cooler.
The conveying device includes a heating / cooling device that heats and cools the inside of the conveying device, a thermometer that detects a temperature of an outlet of the conveying device, and the heating / cooling device based on the temperature detected by the thermometer. A temperature control unit that controls heating and cooling in the transfer device, and by controlling the heating and cooling in the transfer device by the heating and cooling device in the temperature control unit , the plastic in the transfer device, molten plastic cooled and solidified and wherein the cooling to Rukoto in a temperature range where the fluidity of the plastic is maintained. It is a molten plastic cooling solidification apparatus of Claim 3 , Comprising: At least any one between the said container and the said conveying apparatus and between the said conveying apparatus and the said belt cooler WHEREIN: A foreign material from the plastics in a molten state A molten plastic cooling and solidifying device comprising a foreign matter removing device for removing.

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