JP2002037916A - Method for heat-treatment of plastic and heat-treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-treating apparatus and a heat-treating method for plastics effective for preventing the clogging of system with sublimate and enabling easy removal of the sublimate from recovered organic solvent. SOLUTION: A plastic material is heat-treated by heating and melting in a reaction vessel 1 in a state mixed with an organic solvent and the solvent is evaporated and removed from the reaction vessel 1. The evaporated organic solvent is passed through a 2nd waste gas introducing line and introduced into the liquid 21 in a liquid container 20. The liquid 21 in the liquid container 20 is transferred to a solid-liquid separator 24 to remove the sublimate and cooled with a condenser 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment for heat-treating a plastic in an organic solvent, such as a dechlorination treatment for waste plastic, and more particularly to a plastic characterized by the recovery of the organic solvent after the heat treatment of the plastic is completed. And a heat treatment method and apparatus.

[0002]

2. Description of the Related Art In recent years, waste plastics may be reused as solid fuel. For example, "Plastics Vo
l. 47, no. As described in “7, p60”, plastics are used as solid fuels by directly pulverizing waste plastics with a pulverizer. But,
Rigid plastics can only be crushed to a particle size of 1 to 2 mm, and this crushing requires a great deal of time and expense, and fibrous or film-like plastics are difficult to crush. In order to cope with this, it is necessary to apply heat treatment to the waste plastic to melt and solidify it, so that the waste plastic can be easily crushed.

[0003] Further, since waste plastics generally contain plastics containing chlorine such as polyvinyl chloride, if the waste plastics are used as they are as solid fuels or reducing agents for ore, they are generated in the heating process. Hydrogen chloride causes corrosion of heating equipment (furnace, piping, etc.) and air pollution. For this reason, usually, as a pretreatment for converting the waste plastic into a solid fuel or a reducing agent for ore, a heat treatment for dechlorination is performed by heating the plastic containing the chlorine-containing plastic.

[0004] In the heat treatment of the plastic, the waste plastic is heated in a reaction vessel to thermally decompose the chlorine-containing plastic to generate hydrogen chloride gas. The generated hydrogen chloride gas is guided from the reaction vessel to a gas treatment facility through an exhaust gas guide path, and gas treatment is performed. The gas treatment is performed by, for example, cooling the exhaust gas once with a cooling device and then neutralizing the exhaust gas with an alkali, or trapping it in water and collecting it as hydrochloric acid.

Here, as the heat treatment of the plastic, there is a direct method in which only the plastic is directly heated. However, as described in Japanese Patent Application Laid-Open No. 11-292976, the plastic is mixed with an organic solvent. There is a solvent mixing method for heating the plastic.
In this solvent mixing method, by mixing an organic solvent, the plastic being heated can be easily stirred and heat conduction is improved, so that heating of the plastic is efficiently performed or hydrogen chloride gas is generated. There are advantages such as an easy atmosphere.

However, when heat treatment (dechlorination treatment) of the plastic is carried out by the above-mentioned solvent mixing method, the plastic after the heat treatment is in a swollen state, and it is difficult to pulverize as it is. It is easy to agglomerate later, and is likely to cause blockage when transported by piping. That is, it is difficult to obtain a fine solid fuel or the like which is excellent in flammability and easy to handle.

For this reason, in the prior art, Japanese Unexamined Patent Application Publication No.
As described in Japanese Patent Publication No. 1-292976, the organic solvent in the reaction vessel is further evaporated by heating, and the gasified organic solvent is discharged out of the reaction vessel through an exhaust gas guide path. This makes it possible to obtain a melt-solidified and dried plastic with improved pulverizability,
It is possible to obtain a finely divided solid fuel that is relatively easy to handle.

At this time, in order to reuse the organic solvent, the gasified organic solvent is condensed and recovered by a cooling device including a heat exchanger interposed in the exhaust gas guide tube.

[0009]

However, waste plastics often contain foreign substances such as PET (polyethylene terephthalate), wood chips and paper chips due to the nature of waste. Therefore, when waste plastic is heated,
Sublimates, which are decomposition products such as the PET, wood chips, and paper chips, are generated. Usually, in the heat treatment of plastics, after reflux (reflux) near the boiling point of the solvent, the solvent is removed under reduced pressure and / or further heating. At the time of reflux, the adhesion of sublimates to the cooling device and the pipeline is relatively small due to the washing effect of the condensed organic solvent and the like, but the adhesion of sublimates tends to increase significantly at the time of desolvation. As a result, the cooling device and the pipeline may be blocked.

[0010] Further, since the fine powder of sublimate (solid matter) is mixed in the organic solvent recovered by desolvation, the recovered organic solvent is reused for the next heat treatment of waste plastic, When repeated, the concentration of the sublimate remaining in the system gradually increases. For this reason, the adhesion amount of the sublimate in the cooling device and the pipeline is further increased, which causes blockage. The present invention has been made in view of the above-mentioned problems, and a plastic heat treatment apparatus and a heating apparatus capable of preventing clogging of the system by sublimates and easily removing sublimates from the collected organic solvent. It is an object to provide a processing method.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 is to provide a method in which a plastic is mixed with an organic solvent, and then the organic solvent is mixed with the organic solvent. In the method for heat-treating plastic by evaporating and removing the mixture from the above, a liquid container containing a liquid and cooling means for cooling the liquid in the liquid container are provided, and the evaporated organic solvent is removed from the liquid container. It is characterized in that it is condensed and recovered by being guided into a liquid.

The above liquid is preferably a liquid having the same composition as the above organic solvent, which does not require a separation operation. Next, according to a second aspect of the present invention, in addition to the configuration of the first aspect, a circulation path for circulating the liquid in the liquid container is provided, and a solid-liquid separation device is interposed in the circulation path. It is characterized by the following. Next, the invention according to claim 3 is characterized in that the cooling means controls the temperature of the liquid in the liquid container by cooling the liquid flowing through the circulation path, in contrast to the configuration described in claim 2. Is what you do.

Next, a fourth aspect of the present invention provides a reaction vessel containing a mixture of a plastic and an organic solvent, and heating means for heating the mixture in the reaction vessel. A liquid container containing a liquid in a plastic heat treatment device that heats the inside of the container and heat-treats the plastic together with an organic solvent, and then gasifies the organic solvent in the reaction container and discharges the outside of the reaction container. And a gas guide pipe for guiding the evaporated organic solvent into the liquid in the liquid container, and cooling means for cooling the liquid in the liquid container.

According to a fifth aspect of the present invention, in addition to the structure of the fourth aspect, a circulation path for circulating the liquid in the liquid container is provided, and a solid-liquid separation device is interposed in the circulation path. It is characterized by having made it. Next, according to a sixth aspect of the present invention, in the configuration according to the fifth aspect, the cooling means is interposed in the circulation path to cool the liquid flowing through the circulation path. is there.

According to the present invention, by introducing the evaporated organic solvent into the liquid, the liquid is cooled by the liquid to condense (liquefy) the organic solvent, and the sublimate mixed in the organic solvent is also contained in the liquid. Precipitates (becomes a fine solid).
Since the main body of the cooling device (condenser) for recovering the organic solvent is composed of the liquid container containing the liquid, the liquid container (cooling device) for recovering the organic solvent is prevented from being blocked by the sublimate. You.

Here, the present inventors have confirmed that the precipitated sublimate has a property of settling in a liquid having a density of 1200 kg / m ³ or less. Therefore, if a liquid having a density of 1200 kg / m ³ or less is used as the liquid, the deposited sublimate sediments and deposits on the bottom of the liquid container, and the sublimate is automatically separated and removed from the organic solvent. When the same liquid as the organic solvent mixed with the plastic is used as the liquid, the density is 1 unit.
An organic solvent of 200 kg / m ³ or less may be employed. Examples of such an organic solvent include a coal-based tar distillate, heavy oil A, and light oil.

Further, the sublimate precipitated in the liquid container is a fine solid, so that the liquid in the liquid container is circulated for solid-liquid separation according to the invention. Sublimates in the liquid are removed by passing through the device. As a result, the sublimate can be easily separated and
Removal is performed. According to the third aspect of the present invention, the temperature of the liquid in the liquid container is adjusted to a predetermined temperature by cooling the circulating liquid. Since the entire liquid in the liquid container is not cooled, the size of the cooling means can be reduced, and the degree of freedom of arrangement of the cooling means can be improved.

Here, the boiling point of the organic solvent is preferably higher than 150 ° C. In addition, the above-mentioned sublimate is 150 ° C.
In the following, it is confirmed that the gaseous state returns to the solid state. Therefore, the temperature of the liquid in the liquid container may be adjusted to 150 ° C. or lower. However, in order to facilitate circulation in the circulation path, the liquid temperature may be set higher to lower the viscosity of the organic solvent.

[0019]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating a plastic heat treatment apparatus according to the present embodiment.
Reference numeral 1 denotes a reaction vessel in which chlorine-containing plastics such as polyvinyl chloride and waste plastics such as polyethylene, polypropylene, polyethylene terephthalate, and polystyrene are roughly crushed (for example, 10
while being housed in a state of
Organic solvent is mixed. When the waste plastic is in the form of a film, sheet, or fiber, it may be stored in the reaction vessel 1 as it is.

Here, the mass ratio of the organic solvent and the plastic in the mixture of the plastic and the organic solvent, that is, the preferable range of the organic solvent / plastic [mass ratio] is 0.1 to 10, and more preferably 0.1 to 10. 0.5 ~
5 range. When the mass ratio is less than 0.1, the viscosity of the system becomes high, handling becomes difficult, and dechlorination hardly occurs. Conversely, when the mass ratio exceeds 10, the reaction vessel 1
This is disadvantageous in terms of the size and the distillation cost when removing the organic solvent from the plastic processing product.

As described above, the plastic and the organic solvent are contained in the reaction vessel 1 at room temperature, and after mixing the plastic and the organic solvent into the reaction vessel 1 for 15 minutes.
The heat treatment may be performed by heating to a temperature of 0 ° C. or higher and increasing the temperature (in the following description, an example of this case will be described). Alternatively, one of the plastic and the organic solvent may be first charged into the reaction vessel 1 and heated to a temperature of 150 ° C. or higher, and then the other may be charged, or at least one of them may be heated to 150 ° C. or higher. May be charged into the reaction vessel 1 from the above. The mixed system of the plastic and the organic solvent obtained by making such a mixed state may be a uniform system (all dissolved) or may remain partially in a solid state (swelled state) that cannot be completely dissolved. .

Examples of the organic solvent include heavy oil A (boiling point: 280 to 290) which is a petroleum organic solvent.
° C), light oil (boiling point: 240 to 250 ° C), kerosene (boiling point:
190 to 200 ° C.), crude naphtha oil (boiling point: 190 to 200 ° C.) which is a coal-based organic solvent, and washing oil (boiling point: 200
Organic solvents capable of dissolving and swelling plastic, such as creosote oil (boiling point: about 280 ° C.).

The inside of the reaction vessel 1 is heated by a heating means 2 such as a heater. The heating means 2 controls the amount of heat supplied to the reaction vessel 1 based on a command from the controller 3. The reaction vessel 1 is provided with a stirrer 4, which stirs a mixture of a plastic and a solvent (hereinafter referred to as a plastic 5) in the reaction vessel 1 so that the temperature of the plastic 5 or the like becomes uniform. And so on.

The liquid temperature of the plastic or the like 5 in the reaction vessel 1 is measured by a first thermometer 6.
Outputs the measured temperature to the controller 3 as a signal. The reaction vessel 1 is connected to two exhaust gas guide paths 7 and 8 for guiding gas generated in the tank to the outside of the tank. That is, the exhaust gas guide path is composed of two systems: the first exhaust gas guide path 7 and the second exhaust gas guide path 8 constituting the gas guide pipe. A first on-off valve 9 and a second on-off valve 10 for opening and closing the conduits are provided at positions near the reaction vessel 1 in the two guide paths 7, 8, respectively.
The opening and closing of each valve is controlled by a command from the controller 3.

The downstream end of the first exhaust gas guide path 7 is connected to an absorption tank 11 which is a gas processing device. And the first
The exhaust gas guided to the exhaust gas guide path 7 is released into the atmosphere, for example, after hydrogen chloride is removed in the absorption tank 11. As an example of the absorption tank 11, a tank filled with an aqueous solution of sodium hydroxide can be exemplified. On the downstream side of the first on-off valve 9 in the first exhaust gas guide path 7 (on the side of the absorption tank 11), a cooling device 12 constituting a condenser is interposed. The cooling device 12 composed of a heat exchanger or the like cools the sent exhaust gas to T ° C. (usually a temperature several degrees lower than the boiling point of the organic solvent), and removes components having a boiling point higher than T ° C. ,
It is liquefied or solidified and separated from the exhaust gas.

The outlet of the cooling device 12 is connected to the first pipe 1
The organic solvent separated from the exhaust gas by being connected to the inlet of the filtration device 14 via 3 is supplied to the filtration device 14.
To reduce the viscosity, the organic solvent in the filtration device 14 is preferably heated to T ′ ° C. (below the boiling point of the organic solvent) by a solvent heating means 15 such as a heater. Reference numeral 14a represents a filter of the filtering device 14. The outlet of the filtration device 14 communicates with the upper portion of the reaction vessel 1 through a solvent return path 16 so that the organic solvent filtered by the filtration device 14 by the pump 17 can be returned to the reaction vessel 1 as appropriate.

The downstream end of the second exhaust gas guide path 8 is immersed in the liquid 21 in the liquid container 20 to guide the exhaust gas guided by the second exhaust gas guide path 8 into the liquid 21. . In the present embodiment, the same liquid 21 as the organic solvent contained in the reaction vessel 1 is used as the liquid 21, and the work of separating the collected organic solvent and the liquid 21 is not required.

The liquid container 20 includes the liquid container 20.
A circulation path 22 that circulates the liquid 21 inside is connected. That is, the circulation path 22 has one end (upstream side) communicating with the lower part (lower than the liquid surface) of the liquid container 20 and the other end (downstream side) communicating with the upper part of the liquid container 20. . A pump 23, a solid-liquid separator 24, and a condenser 25 including a heat exchanger are interposed in the circulation path 22 from the upstream side. Further, the circulation path 22 has a discharge pipe 26 branched downstream of the condenser 25,
A part of the circulating organic solvent can be discharged to the collection container 27.

Further, a third on-off valve 30 is inserted in a portion of the circulation path 22 upstream of the installation position of the condenser 25, and
A fourth on-off valve 31 is also interposed in the discharge pipe 26 so that the amount of liquid that has been cooled by the condenser 25 and returned to the liquid container 20 can be adjusted. Since the liquid 21 flowing through the discharge pipe 26 does not need to be cooled, the discharge pipe 26 may be branched from the circulation path 22 between the solid-liquid separation device 24 and the condenser 25.

Examples of the solid-liquid separation device 24 include a centrifugal separation system, a filtration separation system, and a liquid cyclone. Further, the liquid container 20 is provided with a level meter 28 for measuring the liquid level and a second thermometer 29 for measuring the liquid temperature in the liquid container 20, and supplies a measurement signal to the controller 3. ing.

Reference numeral 40 denotes a vacuum pump, and reference numeral 41 denotes a vacuum pump.
Represents a water seal trap for water seal, respectively. The controller 3 includes a heat treatment unit 3A for controlling the heat treatment (dechlorination treatment) of the plastic, and a solvent evaporation unit 3B for controlling the evaporation and removal of the organic solvent. The heat treatment section 3A is
An open command is supplied to the on-off valve 9 and a close command is supplied to the second on-off valve 10. Subsequently, based on a signal from the first thermometer 6, control is performed via the heating means 2 so that the heating temperature of the plastic or the like 5 in the reaction vessel 1 becomes a target set temperature. The set temperature is, for example, 150 ° C. to 450 ° C.
The temperature may be set in the range of ° C.

Here, by heating the plastic to a temperature of 150 ° C. or more in the presence of an organic solvent, the entanglement of the polymer of the plastic is loosened and a part of the bond is broken, whereby the solid matter after the removal of the solvent is removed. Of the resulting plastic product is easily pulverized. If the temperature of the system in the mixed state was lower than 150 ° C., the hardness of the solid obtained after removing the solvent was almost the same as that of the original plastic, and it was difficult to pulverize the solid. On the other hand, if the temperature of the system in the mixed state rises above 450 ° C., the yield of solids decreases due to gasification or oilification of the plastic. Therefore, in the present embodiment, the lower limit of the temperature of the mixed system of the plastic and the organic solvent is set to 150 ° C. or more, and the upper limit is set to 450 ° C. The temperature is more preferably 160 to 400 ° C, still more preferably 180 to 380 ° C, still more preferably 20 to 380 ° C.
The temperature range is 0 to 350 ° C. Further, it is preferable that the holding time at a temperature of 150 ° C. or more is longer, since dehydrochlorination can be performed more reliably and the solid after removal of the solvent becomes brittle. However, if the time is too long, decomposition and gasification proceed, causing problems such as a decrease in the yield of the target solid and a decrease in the processing capacity of the equipment. For this reason, 150
The time at which the temperature is maintained at not less than 10 ° C is preferably 10 minutes to 6 minutes.
The time is more preferably in the range of 30 minutes to 3 hours.

The solvent evaporator 3B supplies a close command to the first on-off valve 9 and also supplies an open command to the second on-off valve 10. Subsequently, based on a signal from the second thermometer 29,
Control is performed via the heating means 2 so that the heating temperature of the plastic or the like 5 in the reaction vessel 1 becomes a target set temperature. For example, the heating temperature (distillation temperature) is 150 to 4
A range of 00 ° C. is preferred.

As the distillation method, any of normal pressure distillation and reduced pressure distillation may be used, but reduced pressure distillation is preferable because the removal efficiency of the organic solvent, low boiling point components and sublimation components is higher, and the atmospheric pressure of the object to be treated ≦ ( More preferably, a vacuum distillation method under a pressure condition of (atmospheric pressure-66.66 kPa) is used. Next, an operation, an operation, an effect, and the like of the plastic heat treatment apparatus having the above configuration will be described.

When the plastic and the organic solvent are charged into the reaction vessel 1, first, the heating section 3 of the controller 3
A operates to close the second exhaust gas guide path 8 and open the first exhaust gas guide path 7. At the same time, the heating of the reaction vessel 1 is started. Then, the plastic or the like 5 in the reaction vessel 1 has a predetermined dechlorination start temperature (150 ° C.).
When heated as described above, the plastic melts to generate hydrogen chloride gas, and the amount of generated hydrogen chloride gas increases with an increase in the heating temperature. Also, as the heating temperature rises,
Organic solvents also gasify. Then, the exhaust gas mainly composed of the hydrogen chloride gas and the gasified organic solvent flows in the first exhaust gas guide path 7. In addition, decomposed substances such as PET, wood chips, and paper chips mixed in the plastic are sublimated together with the start of the dechlorination (generation of hydrogen chloride gas) by heating, and the sublimates are also mixed in the exhaust gas.

The exhaust gas guided to the first exhaust gas guide path 7 is cooled to T ° C. (usually a temperature several degrees lower than the boiling point of the organic solvent) by the cooling device 12, and the organic solvent in the exhaust gas is condensed. It is returned to the liquid 21. At this time, the sublimate in the exhaust gas is also separated and collected together with the organic solvent as fine (or fine) solids. The collected organic solvent is sent to the filtration device 14, and the filter 14a of the filtration device 14
The fine sublimate is captured and only the liquid organic solvent is recovered. The organic solvent from which the sublimate has been removed is appropriately returned to the reaction vessel 1.

As a result, the amount of the organic solvent in the reaction vessel 1 is always kept at a predetermined value or more during heating, so that the plastic can be heated in the organic solvent. Further, since most of the sublimate is removed from the organic solvent collected and returned to the reaction vessel 1, the concentration of the sublimate in the system is prevented from increasing, and the sublimate concentration in the system is prevented from being increased. This prevents the cooling device 12 and the like from being blocked by the sublimate due to the adhesion of the sublimate.

Further, since the organic solvent is heated to T '° C. when the sublimate is removed from the collected organic solvent by filtration, the speed at which the organic solvent passes through the filter 14a is accelerated, and the time required for separating the sublimate is increased. Can be shortened.
The higher the temperature T 'at which the organic solvent is heated, the higher the filtration efficiency. Therefore, the higher the temperature, the better, but the temperature is lower than the boiling point.
However, if the temperature exceeds 150 ° C., the sublimate may be sublimated again.
It is preferable to keep the temperature at or below ° C.

According to the investigation by the present inventors, the amount of sublimation of decomposed products of wood chips and paper chips mixed in plastic peaks at about 220 ° C., and further 230 ° C.
Sublimation of most of the decomposition products of PET, wood chips and paper chips is completed by then. Also, depending on the type of the organic solvent, the above-mentioned about 220
C is a temperature range in which the amount of gasification of the organic solvent is small.
Therefore, the heating temperature at which the organic solvent starts gasification or the heating temperature at which the amount of gasification is small (eg, lower than the boiling point of the organic solvent) or the heating temperature at 230 ° C or lower at which the sublimation of most of the sublimate is completed. In the temperature state, the collected material collected by the cooling device 12 is not supplied to the filtration device 14 but is collected in another container or the like, thereby the filtration device 14
The amount of the sublimate to be filtered may be suppressed to improve the filtration efficiency in the filtration device 14. With respect to the collected matter collected in another container, the organic solvent may be separately separated into an organic solvent and a sublimate by a sedimentation separation device or the like.

Further, in the above embodiment, the organic solvent from which the sublimate has been removed by the filtration device 14 is directly returned to the reaction vessel 1 through the solvent return path 16. It may be collected in a container and returned to the reaction container 1 from the other container. In the present embodiment, the solvent heating means 15 is provided, but need not be provided. However, the filtration efficiency is deteriorated accordingly. Further, the organic solvent in the filtration device 14 is heated by the solvent heating means 15, and the filtration is performed by interposing the solvent heating means 15 in the middle of the first pipe 13 between the cooling device 12 and the filtration device 14. The organic solvent sent to the device 14 may be heated.

Further, when the controller 3 determines that the heat treatment (dechlorination treatment) of the plastic is completed based on the concentration of hydrogen chloride gas in the exhaust gas, the elapsed time of heating, and the like,
The solvent evaporator 3B is operated to discharge the organic solvent from the reaction vessel 1. First, the first exhaust gas introduction path 7 is closed and the second exhaust gas guide path 8 is opened. Subsequently, the inside of the reaction vessel 1 is heated to a temperature at which the organic solvent evaporates. Thereby, the organic solvent in the reaction vessel 1 is gradually gasified and discharged through the second exhaust gas guide path 8. Further, with the gasification of the organic solvent, the sublimate mixed in the organic solvent also sublimes and is discharged from the second exhaust gas guide path 8 together with the organic solvent. The gas containing the organic solvent as a main component is guided to the second exhaust gas guide path 8, guided into the liquid 21 in the liquid container 20, and cooled by the liquid 21. As a result, in the liquid 21, the organic solvent is liquefied and the sublimate mixed in the organic solvent is also precipitated (solidified).

Thus, the organic solvent is removed from the reaction vessel 1 and the organic medium is collected in the liquid vessel 20. Further, the solvent evaporator 3B supplies a drive command to the pump 23, so that the liquid 21 (including the collected organic solvent) in the liquid container 20 is pressure-fed so as to forcibly circulate in the circulation path 22. . As a result, the sublimate that is a solid content mixed in the liquid 21 is separated and removed by the solid-liquid separator 24, and the concentration of the sublimate in the liquid 21 decreases.

Further, the liquid 2 passing through the solid-liquid separation device 24
1 is returned to the liquid container 20 after being cooled by the condenser 25, thereby lowering the liquid temperature in the liquid container 20 to a predetermined temperature or lower (for example, 150 ° C. or lower). At this time, the solvent evaporator 3B adjusts the opening degree of the third on-off valve 30 based on signals from the second thermometer 29 and the level meter 28, and adjusts the amount of liquid returned to the solvent evaporator 3B. Thus, the level of the liquid level in the liquid container 20 is adjusted to a predetermined range. At the same time, by controlling the temperature and supply amount of the cooling medium supplied to the condenser 25 while considering the amount of the liquid 21 to be returned to the liquid container 20, the temperature of the liquid 21 to be returned to the liquid container 20 is controlled. Is adjusted to a predetermined target temperature. The liquid 21 that is not returned to the liquid container 20 controls the opening of the fourth on-off valve 31 and controls the opening degree of the
To be discharged.

Incidentally, the second exhaust gas guide path 8
The supply amount of heat per unit time supplied to the liquid container 20 through the liquid container 20 can be estimated in advance, so that the heat amount in the liquid container 20 is set to a temperature and a supply amount of a cooling medium that can cool the liquid container 20, and The temperature and the supply amount of the cooling medium may not be dynamically controlled. In this case, by adjusting the liquid level to a predetermined level range, the heat capacity in the liquid container 20 is adjusted to a predetermined range.

As described above, in order to recover the evaporated organic solvent in the liquid 21, even if a sublimate is mixed in the recovered organic solvent, the liquid container 20 for liquefying and recovering the organic solvent is used. The inside is not blocked by sublimates. Further, the sublimate mixed in the collected organic solvent is removed by the solid-liquid separator 24 during the collection of the organic solvent. Even if reuse for heating is repeated, the concentration of the sublimate in the system of the plastic heat treatment apparatus does not increase. In other words, it is difficult for the sublimate to adhere to a pipe or the like in the system due to the sublimate, and the pipe or the like is less likely to be blocked. As a result, the maintenance interval for the sublimate of the heat treatment apparatus can be extended.

Further, since the cooling of the liquid 21 in the liquid container 20 is also performed on the liquid 21 flowing through the circulation path 22, the cooling means can be downsized as compared with the case where the entire inside of the liquid container 20 is cooled. it can. Of course, the inside of the liquid container 20 may be directly cooled without providing the condenser 25 in the circulation path 22. As the liquid 21, that is, as an organic solvent, a coal-based tar distillate having a density of 1200 kg / m ³ or less, heavy oil A, light oil, or the like is preferably used.
In this case, the sublimate sediments and separates in the liquid container 20, and the separation of the sublimate is promoted.

The liquid 21 is not limited to an organic solvent, but may be a liquid such as water. However, a liquid that can be easily separated from the organic solvent is preferable. As described above, the vacuum pump 40 may be operated to promote desolvation, but the vacuum pump 40 may be omitted. In addition, each of the above-described processes (the heat treatment to the plastic and the desolvation process) may be performed by a batch system or a continuous system.

Although the heat treatment of the plastic is exemplified by a dechlorination treatment, it is not limited to this. The present invention can be applied to a plastic containing no chlorine-containing plastic or to a recovery of an organic solvent after a heat treatment for facilitating pulverization. Further, the organic solvent does not need to be completely removed from the reaction vessel 1. It is sufficient that the plastic processed material obtained after cooling and solidification has excellent pulverizability, is easily pulverized, and is easily transported.
% Or less of the organic solvent may remain. In order to improve the ignitability in a boiler or the like when used as a fuel, it is also effective to leave a solvent in the processed material. Also, the smaller the amount of organic solvent remaining in the plastic,
The resulting plastic is easy to pulverize and does not cause agglomeration of the pulverized material. However, severe conditions (high temperature and high vacuum) are required for desolvation. Although the transfer of the residue (residue) becomes easy, the pulverized product is difficult to pulverize, and the pulverized material is easily aggregated and the solvent cost is increased.

[0049]

EXAMPLES Examples of the above embodiment based on the present invention will be described below. [Example 1] Iron reaction vessel 1 with a stirrer having an inner volume of 50 L
20 kg of heavy oil A as an organic solvent and polyethylene 3
kg, polypropylene 2.6 kg, polystyrene 3.6
kg of polyethylene terephthalate, 0.3 kg of soft vinyl chloride, and 0.3 kg of hard vinyl chloride, respectively, were charged, and the temperature was raised by a heater (heating means 2) on the outer wall of the reaction vessel 1. The average chlorine content in the plastic was 2.4%.

As shown in FIG. 1, a reaction container 1 is a liquid container 2 containing 10 kg of heavy oil A as a liquid 21 therein.
0 (50 L of internal capacity). At the gas outlet of the liquid container 20, a water seal trap 41 was installed. Further, a vacuum pump 40 was installed in parallel with the water seal trap 41. After the heat treatment of the processed material in the reaction vessel 1 at 240 ° C., the material was further heated, and the evaporant was discharged into the liquid 21 in the liquid container 20.
The ambient temperature in the condenser 25 was controlled so that the liquid 21 in the liquid container 20 had a liquid temperature of 50 ° C.

When the temperature of the plastics 5 in the reaction vessel 1 reached 300 ° C., distillation under reduced pressure (absolute pressure: 6.66 kPa) was performed, and the solvent was removed. Was obtained and cooled to room temperature to give a black coal-like solid (: lump). The residual chlorine in the solid was 0.2%. 50 g of this black lump was charged into a rotary blade pulverizer and pulverized. As a result, pulverization was extremely easy, and a fine powder having an average particle diameter of 1 mm was obtained in a pulverization interval of 20 seconds.

Further, since 28.5 kg of heavy oil slurry was obtained from the liquid container 20, this was filtered with a qualitative filter paper to obtain 28.3 kg of heavy oil and 0.2 kg of solid matter. When the inside of the liquid container 20 was opened and inspected,
About several g of white powder was slightly adhered.

[Example 2] In addition, 20 kg of heavy oil A as an organic solvent and 10 k of plastic selected from municipal waste
g was charged into the reaction vessel 1, and the same operation was performed using the same apparatus configuration as in Example 1 except that the temperature of the vacuum distillation was set to 320 ° C. As a result, 9.2 kg of a black solid (: lump) and 2
9.1 kg of heavy oil slurry was obtained. The residual chlorine in the solid was 0.3%.

50 g of this black lump was charged into a rotary blade type pulverizer and pulverized. As a result, pulverization was extremely easy, and a fine powder having an average particle diameter of 1 mm was obtained in a pulverization time of 30 seconds.
When the slurry obtained from the liquid container 20 was filtered with qualitative filter paper, 28.7 kg of heavy oil and 0.4 kg of a solid were obtained. When the inside of the liquid container 20 was opened and inspected,
As in Example 1, about several g of white powder was slightly adhered.

[Comparative Example 1] In a 50-liter iron-made reaction vessel equipped with a stirrer, 20 kg of A heavy oil as an organic solvent, 31 kg of polyethylene, 2.6 kg of polypropylene, 3.6 kg of polystyrene, and 0.2 kg of polyethylene terephthalate were used.
kg, soft vinyl chloride 0.3 kg, hard vinyl chloride 0.
3 kg of commercially available pellets were charged, and the temperature was raised by a heater on the outer wall of the reaction vessel. The average chlorine content in the plastic was 2.4%.

The vapor of the organic solvent discharged from the reaction vessel 1 was recovered by a water-cooled multi-tube condenser as a heat exchanger.
A water ring trap was installed at the gas outlet of the water-cooled multi-tube condenser. In addition, a vacuum pump was installed in parallel with the water ring trap. After the heat treatment of the processed material in the reaction vessel 1 at 240 ° C., it was further heated, and the evaporated material was discharged to a multi-tube condenser. The amount of water was controlled so that the outlet temperature of the water-cooled multi-tube condenser became 50 ° C.

When the temperature of the treated product in the reaction vessel 1 reaches 300 ° C., distillation under reduced pressure (absolute pressure: 6.66 kPa) is performed to remove the solvent (including components having a low boiling point). As a result, a pitch-like residue was obtained. When this was cooled to room temperature, a black coal-like solid (: lump) was obtained. The residual chlorine in the solid was 0.2%. Since 28.3 kg of heavy oil slurry was obtained from the liquid passage portion of the water-cooled multi-tube condenser, this was filtered through qualitative filter paper to obtain 28.2 kg of heavy oil and 0.1 kg of solid matter.

When the inside of the water-cooled multitubular condenser was inspected openly, about 100 g of white powder was closely adhered. That is, it turns out that it is blocked unlike the present invention. [Comparative Example 2] Also, 20 kg of heavy oil A was used as an organic solvent,
A similar operation was attempted using the same apparatus configuration as in Comparative Example 1 except that 10 kg of plastic selected from municipal waste was put into the reaction vessel 1.

However, when the temperature of the processed material in the reaction vessel 1 is 2
When the temperature reached 45 ° C., the operation was stopped because a large amount of oil was found to be mixed in the water seal trap. When the piping between the water-cooled multitubular condenser and the reaction vessel was opened and inspected, it was found to be blocked by a gray solid having a bulk density of about 0.2 g / cm ³ . It was also confirmed that the same solid was adhered to the inside of the water-cooled multi-tube condenser.

As shown in Examples 1 and 2 described above, the apparatus of the present invention did not suffer from an operation trouble such as blockage of the cooling device and the pipeline. On the other hand, as in the comparative example, a water-cooled multi-tube condenser that is frequently used in a distillation column or the like is cooled by a cooling device (solvent recovery device) during evaporation
When used as, sublimate adheres remarkably, and in some cases, it is impossible to stably rotate (Comparative Example 2)
You can see that.

[0061]

As described above, when the present invention is adopted, the organic solvent evaporated from the reaction vessel is guided into the liquid and is recovered, so that the volatile matter is collected when the solvent is recovered as in the prior art. Clogging in the cooling device and the pipeline due to this can be suppressed. As a result, it is possible to extend the continuous operation time of the plastic heat treatment and set the maintenance inspection interval to be long. This means that the heat treatment for obtaining a solid fuel having a low chlorine content and a reducing agent for a blast furnace can be performed more economically.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing equipment of a plastic heat treatment apparatus according to an embodiment based on the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Heating means 3 Controller 3A Heat treatment part 3B Solvent evaporation part 4 Stirrer 5 Plastic etc. 6 First thermometer 7 First exhaust gas guideway 8 Second exhaust gas guideway 9 First on-off valve 10 Second on-off valve DESCRIPTION OF SYMBOLS 11 Absorption tank 12 Cooling device 13 1st line 14 Filtration device 14a Filter 15 Solvent heating device 16 Solvent return line 17 Pump 20 Liquid container 21 Liquid 22 Circulation line 23 Pump 24 Solid-liquid separation device 25 Condenser (cooling means) 26 Discharge pipe 27 Collection container 28 Level gauge 29 Second thermometer 30 Third on-off valve 31 Fourth on-off valve 40 Vacuum pump 41 Water seal trap

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Tatsuya Shinzawa, 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Laboratory, Kawasaki Steel Works (72) Inventor Toshihide Suzuki 1, Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Address Kawasaki Steel Engineering Co., Ltd. (72) Inventor Makoto Samurato 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Chiba Works Chiba Works (72) Inventor Kazuya Miyagawa Kawasaki, Chuo-ku, Chiba Chiba No. 1 Kawasaki Steel Corporation Chiba Works (72) Inventor Hideaki Unzaki 1 Kawasaki-cho Chuo-ku Chiba City Chiba Prefecture Chiba Works Chiba Works F-term (reference) 4D076 AA02 AA12 AA13 AA22 BA02 BC14 CD03 CD22 DA02 EA12Y EA14Y EA15Y FA04 FA18 HA03 JA03 4F301 AA16 AA25 CA09 CA14 CA43 CA53 CA65 CA72 CA73 4H015 AA02 AA17 AB01 BA08 BA12 BB03 CB01

Claims (6)

[Claims] 1. A plastic heat treatment method in which a plastic is mixed with an organic solvent and then subjected to a heat treatment, and then the organic solvent is evaporated from a mixture of the plastic and the organic solvent to remove the plastic. A heat treatment for plastics, wherein a container and a cooling means for cooling the liquid in the liquid container are provided, and the evaporated organic solvent is condensed and recovered by being guided into the liquid in the liquid container. Method. 2. The plastic heat treatment method according to claim 1, wherein a circulation path for circulating the liquid in the liquid container is provided, and a solid-liquid separation device is interposed in the circulation path. 3. The plastic heat treatment method according to claim 2, wherein the cooling means controls the temperature of the liquid in the liquid container by cooling the liquid flowing through the circulation path. 4. A reaction vessel containing a mixture of a plastic and an organic solvent, and a heating means for heating the mixture in the reaction vessel, wherein the plastic is heated by heating the inside of the reaction vessel. In a plastic heat treatment apparatus that gasifies the organic solvent in the reaction vessel and discharges the organic solvent in the reaction vessel after the heat treatment together with the organic solvent, the liquid vessel containing the liquid, A heat treatment apparatus for plastics, comprising: a gas guide pipe for guiding the liquid in a container; and cooling means for cooling the liquid in the liquid container. 5. The plastic heat treatment apparatus according to claim 4, wherein a circulation path for circulating the liquid in the liquid container is provided, and a solid-liquid separation device is interposed in the circulation path. 6. The plastic heat treatment apparatus according to claim 5, wherein the cooling means is interposed in the circulation path to cool the liquid flowing through the circulation path.