JPH079448A - Extruder structure in waste plastic regenerating treatment equipment - Google Patents

Abstract

PURPOSE:To prevent low temp. corrosion and to enhance durability by forming a corrosion-resistant layer to the inner peripheral surface of a casing on the side of the charging port of the casing and forming the feeder up to the start end of a heating system from a hydrogen chloride-resistant material and providing the gas vent releasing the air in the casing heated by the heating system to the open air. CONSTITUTION:The waste plastic from a charging port 2a is sent to a discharge port 2b by the screws 3d-3f and paddles 3g, 3h of a rotary shaft 3 to be primarily melted by a heating jacket 2d. At this time, dechlorination is generated on the side of the heating jacket 2d but steam is discharged from a upstream gas vent pipe 5a and generated hydrogen chloride is discharged from a downstream gas vent pipe 5b. Since the presence of moisture is slight even in a low temp. area, the reaction of generated hydrogen chloride gas is suppressed. A coating layer composed of a phenol resin is provided to the casing 2 on a low temp. side and a retainer ring 3c is also made of a resin. The screws 3d, 3e on a low temp. side and the paddle 3g therebetween are made of an alloy high in hydrogen chloride resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment facility for converting waste plastic containing vinyl chloride into oil to recover it as kerosene, light oil fraction and gasoline fraction, and more particularly to an extruder for primary melting of crushed plastic. It relates to a structure for preventing corrosion.

[0002]

2. Description of the Related Art Equipment for recycling waste plastic is
It is generally known that the process of crushing waste plastics to the recovery of heavy oil and light oil is performed.

FIG. 3 is a flow chart of the process in this equipment, which is roughly divided into a pretreatment device for crushing and selecting waste plastic and an oiling device for recovering the pretreated waste plastic as light oil and heavy oil. . Then, the heavy oil that has been liquefied is used to generate private power, which is used as facility power for operation.

Among these devices, the extruder which constitutes a part of the oiling device heats the raw material supplied in a fixed amount from the waste plastic receiving tank to perform primary melting, and the primary molten material is fed to the raw material mixing tank. It has a function of sending out and has a structure in which a screw shaft is arranged inside the casing.

[0005]

However, hydrogen chloride is generated by the dechlorination reaction of vinyl chloride or the like in the heating process when the waste plastic is first melted. The generated hydrogen chloride causes corrosion in a low temperature region inside the extruder.

Such corrosion occurs due to the following reasons. With this equipment, waste plastics can be heated from room temperature to approximately 300 ° C.
Heat up to. Therefore, there always exists a low temperature region where hydrochloric acid condenses. In this condensation zone, hydrochloric acid violently corrodes the inner surface of the casing of the extruder and the surface metal of the screw shaft mainly by the following reactions.

M + 2HCl → MCl ₂ + H ₂
(M: Fe, Ni, etc.) When the water content of the waste plastic increases, this low temperature corrosion tendency is further accelerated.

The occurrence of corrosion due to hydrogen chloride is conventionally dealt with by adding a neutralizing agent such as CaO. However, such a chemical treatment has various problems such as complicated equipment, increased running cost, and extraction of salt generated in the system.

The problem to be solved in the present invention is to prevent low-temperature corrosion of an extruder that primarily melts waste plastic and improve its durability, and to efficiently perform dehydrochlorination in the extruder, and to provide the equipment at the latter stage and It is to simplify driving.

[0010]

According to the present invention, there is provided a feed port for a raw material of waste plastic, a discharge port for discharging the raw material after the primary melting to a raw material mixing tank, and a feeder for conveying the raw material from the charge port to the discharge port. And an extruder equipped with a heating system for primarily melting the raw material, wherein a feeder up to the starting end of the heating system is formed with a chlorinated water-resistant material while forming a corrosion resistant layer on the inner peripheral surface of the casing on the inlet side. It is characterized by comprising a gas vent passage for releasing the space in the casing heated by the heating system to the outside air.

[0011]

Since there is no heating system on the charging inlet side, the temperature is low, and the casing contained in this low temperature region has a coating layer made of, for example, a phenol resin to provide corrosion resistance. In addition, the feeder uses a hydrogen chloride resistant material to suppress the progress of corrosion due to hydrogen chloride.

On the other hand, not only maintaining the corrosion resistance of such a member, but also providing a gas vent passage for releasing the gas in the heated casing on the downstream side of the low temperature region, the hydrogen chloride generated by the dehydrochlorination is removed. Prevents reaching the low temperature range and discharges steam from raw materials to suppress corrosion reaction due to hydrogen chloride.

[0013]

1 is a vertical sectional view showing an embodiment of an extruder according to the present invention, and FIG. 2 is a view showing an outline of equipment before and after the extruder.

In FIG. 2, an extruder 1 is arranged below a waste plastic receiving tank 50 which is arranged as a preceding stage of the oiling device described in the section of the prior art, and a raw material mixing tank 51 for receiving the primary molten raw material therein. Is disposed downstream thereof, and a thermal decomposition tank 52 is installed downstream of the raw material mixing tank 51.

The waste plastic receiving tank 50 quantitatively supplies the waste plastic to the extruder 1, and the raw material mixing tank 51 almost completely melts the primary melted raw material. Further, in the thermal decomposition tank 52, the melted raw material is thermally decomposed, and the steam of the generated thermal decomposition oil is supplied to the downstream processing step.

The extruder 1 is provided with a raw material inlet 2a on one end of the casing 2 and a raw material discharge port 2b on the lower end of the other end after the primary melting, each of which is provided with a waste plastic receiving tank 50 and a raw material. It is connectable to the mixing tank 51. On the charging port 2a side, a cooling chamber 2c for preventing the raw material from adhering around the charging port 2a is formed around the body, and on the downstream side, a heating chamber 2d in which a heating medium for heating the raw material circulates. Is also provided around the waist.

A rotary shaft 3 is incorporated in the casing 2, and the left end in the drawing is projected to the outside and connected to a drive mechanism (not shown). The right end of the rotary shaft 3 is supported by a bearing 3a and is provided with lantern rings 3b and 3c for sealing the space through which the raw material passes and the outside. A retainer ring 3d is provided on the surface of the lantern ring 3b on the side of the charging port 2a, which faces the raw material passage space.

The lantern ring 3b on the charging port 2a side has
A pipe end of an inert gas supply pipe 4 protruding to the outside of the casing 2 is connected. From the supply pipe 4, for example, an inert gas such as N ₂ is supplied at an appropriate pressure to seal the circumference of the rotary shaft 3. Further, the gas vent pipes 5 are respectively provided at the portions downstream of the charging port 2a and corresponding to the heating jacket 2d.
a and 6a are provided so as to project to the outside, and the inside of the casing 2 is exposed to the atmosphere.

On the other hand, the rotary shaft 3 is provided with screws 3e, 3f and 3g at the portions corresponding to the inlet 2a side and the portions corresponding to the gas vent pipes 5a and 5b, and paddles 3g and 3h are provided at the other portions. The rotary shaft 3, the screws 3e to 3g, and the paddles 3g and 3h constitute a feeder for feeding the raw material to the discharge port 2b side.

The casing 2, the rotary shaft 3, the screw 3f and the paddle 3h are all made of SUS. And in order to prevent corrosion in the low temperature range,
A coating layer 2e of phenolic resin is provided on the inner peripheral surface of the casing 2, and the screws 3d, 3e and the paddle 3g located between them are made of an alloy containing Ni as a base material and containing appropriate amounts of Cr and Mo. Further, as the retainer ring 3d arranged on the charging port 2a side, a retainer ring 3d on which a coating layer of tetrafluoroethylene is formed is used.

Further, the gas vent pipe 5a located on the side of the charging port 2a mainly scavenges the vaporized moisture which is initially generated when the raw material is fed by the screw 3f and heated by the heating jacket 2d. The downstream gas vent pipe 5b mainly scavenges hydrogen chloride gas generated by heating. By providing such gas vent pipes 5a and 5b,
The generated hydrogen chloride gas can be discharged outside before it goes to the charging port 2a side.

In the above construction, the waste plastic from the charging port 2a is sent to the discharge port 2b side by the screws 3d to 3f and the paddles 3g and 3h of the rotary shaft 3 and is primarily melted by the heating by the heating jacket 2d. During this heating, dechlorination occurs on the heating jacket 2d side, but evaporated water is mainly discharged in the upstream gas vent pipe 5a, and the generated hydrogen chloride gas is mainly discharged in the downstream gas vent pipe 5b. Therefore, the presence of water is low even in a low temperature range, so that the casing 2,
The reaction of the generated hydrogen chloride gas with the screws 3d to 3f and the paddles 3g and 3h is suppressed, and corrosion is suppressed.

As described above, by appropriately arranging the gas vent pipes 5a and 5b, generation of NiC1 ₂ and FeC1 ₂ can be prevented, and the casing 2 on the low temperature side 2 and the screw 3
It is possible to suppress the progress of corrosion due to the chemical change of d, 3e and the paddle 3g. Then, the gas vent pipes 5a, 5
Since the screws 3e and 3f are located at the portions corresponding to b, the gas flow can be guided to the degassing pipes 5a and 5b more quickly than the case where they are abutted against the paddles 3g and 3h. It is possible to satisfactorily prevent the movement to the side.

Further, since the casing 2 on the low temperature side is provided with the coating layer 2 made of phenol resin or the like and the retainer ring 3c is also made of resin, corrosion due to hydrogen chloride is prevented. Since the low temperature side screws 3d and 3e and the paddle 3g between them are made of an alloy having high hydrogen chloride resistance, even if hydrogen chloride flows in, the corrosion of the surface thereof rapidly progresses. There is no.

Further, the lantern ring 3b on the side of the charging port 2a
Since an inert gas is supplied from the supply pipe 4, the shaft can be reliably sealed. Further, invasion of moisture from the outside is prevented, and an internal atmosphere in which hydrochloric acid is unlikely to be generated can be maintained.

[0026]

EFFECTS OF THE INVENTION According to the present invention, gas is discharged so that a chemical reaction between hydrogen chloride and a metal, which is mainly caused by dechlorination of vinyl chloride, is unlikely to occur, so that the gas is discharged, so that the low temperature range Corrosion of the members can be prevented, and at the same time, by using these members as a material resistant to chloride water, it is possible to prevent the rapid progress of corrosion even if hydrogen chloride is generated.
Therefore, compared with the conventional structure in which low temperature corrosion is unavoidable, the corrosion resistance is remarkably improved and the running cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of an extruder of the present invention.

FIG. 2 is a schematic view showing the arrangement of oiling devices before and after the extruder.

FIG. 3 is a flow chart showing the steps of oil treatment of waste plastic.

[Explanation of symbols]

 1 Extruder 2 Casing 2a Inlet 2b Exhaust port 3 Rotating shaft 3a Bearing 3b Lantern ring 3c Retainer ring 3d Screw 3e Screw 3f Screw 3g Paddle 3h Paddle 4 Supply pipe 5a Gas vent pipe 5b Gas vent pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahide Tanaka 46-59 Nakahara, Tobata-ku, Kitakyushu, Fukuoka Prefecture 46-59 Nippon Steel Corporation Machinery & Plant Division

Claims (1)

[Claims] 1. A raw material inlet for waste plastic, a discharge outlet for discharging the raw material after the primary melting to a raw material mixing tank, a feeder for conveying the raw material from the inlet to the discharge outlet, and the primary raw material for melting. An extruder having a heating system, which forms a corrosion-resistant layer on the inner peripheral surface of the casing on the inlet side and uses a feeder up to the start end of the heating system as a chlorinated water resistant material.
An extruder structure in a waste plastic recycling treatment facility comprising a gas vent passage for releasing the space in the casing heated by the heating system to the outside air.