JP2622932B2 - Liquefaction of oil vapor from waste plastic melt - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for liquefying oil vapor from a waste plastic melt.

[0002]

2. Description of the Related Art As one of the thermal decomposition methods of waste plastics, waste plastics are melted in a pyrolysis reactor and simultaneously pyrolyzed.
A method has been implemented in which a gas generated by thermal decomposition is sent to a catalyst layer to decompose it into hydrocarbons having a low carbon chain, and then condensed in a cooling and condensing section to recover light oil.

By the way, in such a method, the waste plastic as a raw material is usually discharged from a plastic producer as industrial waste or discharged as separated waste. Therefore, the waste plastic as a raw material contains metals such as wires, clips and screws, and foreign substances such as earth and sand and glass. Such foreign substances are released into the melt during melting in the above-described method, and accumulate in the melt during continuous processing, thereby melting and thermally decomposing the plastic in the pyrolysis reactor. To accumulate. In addition, the polymer chains of the plastic are broken by thermal decomposition to form low molecular hydrocarbons. At this time, inorganic carbon is separated and generated, and accumulates as a residue in the melt in the thermal decomposition reactor. These foreign substances and residues cause a reduction in the thermal decomposition efficiency in the thermal decomposition reactor.

Therefore, conventionally, in order to solve the above-mentioned problem, when the amount of foreign substances and residues in the pyrolysis reactor is increased and the pyrolysis efficiency is reduced, the supply of the waste plastic is stopped and the oil content is reduced. The foreign matter and residue are solidified by completely evaporating (baking), and the foreign matter and residue accumulated after cooling the pyrolysis reactor to near room temperature are manually removed. Then, after removing the foreign matter and the residue, the temperature is raised again and the operation of the apparatus is restarted.

However, in such a method, the energy loss when the apparatus is cooled down to near normal temperature for removing foreign substances and the energy loss required for raising the temperature before re-starting after removing foreign substances become large, resulting in a thermal decomposition. However, there is a problem that fuel consumption required for the vehicle is deteriorated.

[0006] In order to solve the above problem, there is a method of discharging a molten liquid of waste plastic containing foreign matters and residues from the inside of a thermal decomposition reactor by sucking it with, for example, a vacuum pump without stopping the apparatus. It is considered.

[0007] By the way, from the molten liquid of waste plastic discharged from the pyrolysis reactor, oil vapor capable of recovering pyrolysis oil is still generated. The amount of this oil vapor reaches about 1/4 of the melt, but at present it is incinerated without effectively using this oil vapor.

An object of the present invention is to solve the above problems and to provide a method for effectively utilizing oil vapor generated from a molten liquid of waste plastic discharged from a pyrolysis reactor.

[0009]

According to the method of the present invention for liquefying oil vapor from waste plastic melt, waste plastic is melted in a pyrolysis reactor and pyrolyzed , and the generated pyrolysis gas is discharged from the reactor. Removed, cooled, condensed and recovered as pyrolysis oil , and stored in pyrolysis reactor
Pyrolytic foreign matter, the waste plastic melt solution containing the residue obtained by product
It is characterized in that the oil vapor is condensed and liquefied by sucking and removing it from the cracking reactor and spraying the recovered pyrolysis oil into oil vapor generated from the waste plastic melt.

[0010]

When the recovered pyrolysis oil is condensed and liquefied by spraying it into the oil vapor generated from the waste plastic melt, the oil vapor can be recovered as oil.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a waste plastic pyrolysis apparatus.

In FIG. 1, the waste plastic pyrolysis apparatus is provided with a pyrolysis reactor (1) for melting and pyrolyzing raw material plastic and a container for collecting foreign substances and residues (2).

The pyrolysis reactor (1) is placed in a furnace (4) having a heating burner (3). The bottom of the pyrolysis reactor (1) has a concave spherical shape that is concave downward. Supply pipe for waste plastic as raw material to lid (1a) of pyrolysis reactor (1)
(5) is connected to a pyrolysis gas discharge pipe (6).
The supply pipe (5) is connected to a raw material hopper (8) via a valve (7). The discharge pipe (6) is connected to a portion having a catalyst layer (not shown) for further decomposing hydrocarbons. Then, the pyrolysis gas is sent from the pyrolysis reactor (1) through the discharge pipe (6) to the portion having the catalyst layer, where it is further decomposed by the catalyst, and subsequently to the cooling and condensation section. It is sent and condensed, where it is recovered as light pyrolysis oil.

A hollow vertical rotating shaft (9) is disposed through the lid (1a) of the pyrolysis reactor (1). Vertical rotation axis
A seal device (10) seals between (9) and the periphery of the hole through which the rotating shaft (9) in the lid (1a) passes. The lower end of the vertical rotating shaft (9) is located near the bottom of the pyrolysis reactor (1). The upper end of the vertical rotation shaft (9) is located above the lid (1a), and the drive motor (13) is driven via gears (11) and (12).
It is connected to. A plurality of stirring blades (14) are fixedly provided at the lower end of the vertical rotation shaft (9). Each of the stirring blades (14) is curved in a substantially arc shape according to the shape of the bottom surface of the thermal decomposition reactor (1).

Foreign matter and residue suction pipe (15) in vertical rotation shaft (9)
Is arranged. The upper end of the foreign matter and residue suction pipe (15) extends above the upper end of the vertical rotating shaft (9), and the pipe (16)
Is connected to the foreign substance collecting container (2) via A valve (17) is provided between the foreign matter and residue suction pipe (15) and the conduit (16). Vertical rotating shaft (9) upper end and foreign matter, residue suction pipe (15)
Are sealed by a sealing device (18). Further, the lower end of the foreign matter and residue suction pipe (15) is located at substantially the same height as the lower end of the vertical rotation shaft (9).

The foreign matter and residue collecting container (2) is connected through a communication pipe (19) to an oil tank (20) containing the recovered pyrolysis oil (21). Both ends of the communication pipe (19)
Each is connected to the top wall of the foreign matter and residue collecting container (2) and the oil tank (20). A large diameter portion (19a) is formed at the end of the communication pipe (19) on the tank (20) side, and the large diameter portion (19a) is formed.
An oil spray nozzle (22) whose front end faces the inside of the large-diameter portion (19a) and faces inward of the oil tank (20) is attached. The oil spray nozzle (22) extends from the lower end of the oil tank (20) to the oil spray nozzle (22).
3) is connected, and the pyrolysis oil is supplied to the oil spray nozzle (22) through the oil pumping pipe (23) by the pump (24). A vacuum pump (26) is connected to the oil tank (20) via a pipe (25). Valve (27) in the middle of piping (25)
Is provided. Normally, the valve (27) is opened and the valve (17) is closed, and the vacuum pump (26) is operated to operate the conduit (16) and the communication pipe.
(19), the inside of the foreign matter and residue collecting container (2) including the pipe (25) and the oil tank (20) is in a vacuum state.

In such a configuration, the waste plastic mixed with foreign matter such as industrial waste is supplied to the pyrolysis reactor (8) from the raw material hopper (8) through the supply pipe (5) by opening the valve (7). Supplied to 1). This waste plastic is heated and melted by the heat of combustion of the heating burner (3),
It becomes a melt (28). Here, in order to promote the reaction, the vertical rotating shaft (9) is rotated by the drive motor (13), and the melt (28) in the pyrolysis reactor (1) is stirred by the stirring blade (14). Melt (28) is 14
When the temperature is maintained at 0 ° C. or higher, a thermal decomposition reaction occurs, and a thermal decomposition gas is generated. The generated gas is mainly composed of a hydrocarbon gas having 1 to 40 carbon atoms, and is sent to a portion having a catalyst layer through an exhaust pipe (6), where it is further decomposed into hydrocarbons having a low carbon chain. After being cooled, it is sent to a condensing section, where it is cooled and condensed and recovered as light oil.

If such an operation is continued, foreign substances (29) such as metal and glass mixed in the melt (28) accumulate in the pyrolysis reactor (1). In addition, the polymer chain of plastic breaks due to thermal decomposition and becomes low molecular hydrocarbon,
At this time, inorganic carbon is separated and generated and accumulates as a residue (29) in the pyrolysis reactor (1). Then, the foreign matter having a high specific gravity, such as metal and glass, and the residue (29) are removed from the pyrolysis reactor (1) by the coagulation effect of the shape of the stirring blade (14) and the shape of the bottom surface of the pyrolysis reactor (1). It accumulates at the center of the bottom. If the amount of accumulated foreign matter and residue (29) increases, the stirring blade (14) may be damaged or the molten liquid (28) at the bottom of the pyrolysis reactor (1)
This causes a problem of burning. To prevent this, first close valve (17) and close valve (27).
Is opened, and the vacuum pump (26) is operated to evacuate the conduit (16), the communication pipe (19), the pipe (25), the oil tank (20), the foreign matter and the residue collecting vessel (2). deep. Then, pump (2
4) Operate the pyrolysis oil in the oil tank (20) by oil spray nozzle.
Spray from (22). Thereafter, when the valve (17) is opened, the molten liquid (28) in the pyrolysis reactor (1) contains foreign matter and residue.
The foreign matter is sucked into the residue collecting container (2) through the residue suction pipe (15) and the conduit (16) together with (29). Thus,
Foreign substances and residues without stopping the operation of the pyrolyzer (29)
Is removed.

From the melt of the waste plastic sucked into the foreign substance and residue collecting container (2), oil vapor of the same quality as the recovered pyrolysis oil is generated. The amount depends on the temperature of the melt, but it is one-fourth of the melt (melt temperature 300 ° C., degree of vacuum 0.
About 5 kgf / cm ² ) evaporates to generate oil vapor.
The oil vapor reaches the oil tank (20) through the communication pipe (19), and is directly condensed and liquefied by directly touching oil droplets of the pyrolysis oil sprayed from the oil spray nozzle (22).

The oil vapor is condensed and liquefied,
Although a decrease in the degree of vacuum due to a sudden increase in the internal pressure of the oil tank (20) is suppressed, volatilization due to reduced pressure from the pyrolysis oil (21) and
Since volatilization occurs due to an increase in temperature due to condensation of oil vapor in the pyrolysis oil (21), it is better to always operate the vacuum pump (26) to maintain the degree of vacuum. Vacuum pump
The vaporized gas having a low temperature goes to (26), and no high-temperature countermeasures are required.

In the above, since the surface area of the oil droplets of the sprayed pyrolysis oil is extremely large, the efficiency of condensing and liquefying the oil vapor becomes very good. In addition, when the suction of the melt (28) by the vacuum pump (26) is stopped, the pyrolysis oil is prevented from flowing back to the foreign matter and the residue collecting container (2).

[0023]

According to the method for liquefying oil vapor from waste plastic melt according to the present invention, as described above, oil vapor generated from waste plastic melt is recovered as oil and mixed with pyrolysis oil. Can be done. Therefore,
The oil vapor can be effectively used without wasteful incineration. In addition, the oil vapor is sprayed and comes into contact with the oil droplets of the pyrolysis oil having a large surface area to condense and liquefy, so that the efficiency is extremely improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a pyrolysis apparatus for carrying out a method of the present invention.

[Explanation of symbols]

 21 Pyrolysis oil 28 Waste plastic melt 29 Foreign matter, residue

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-313173 (JP, A) JP-A-6-316695 (JP, A) Jiko 4-44608 (JP, Y2)

Claims (1)

(57) [Claims] 1. A waste plastic is melted in a pyrolysis reactor and pyrolyzed , and generated pyrolysis gas is collected from the reactor.
, Cooled, condensed and recovered as pyrolysis oil, and the waste plastic melt containing foreign substances and residues accumulated in the pyrolysis reactor is removed by suction from the pyrolysis reactor,
The oil is recovered from the waste plastic melt.
A method for liquefying oil vapor from a waste plastic melt, wherein the oil vapor is condensed and liquefied by spraying the pyrolyzed oil .