JPH07305076A - Pyrolytic apparatus for plastic - Google Patents

Abstract

PURPOSE:To reduce the energy loss in removing foreign materials, and improve the fuel consumption required for pyrolysis, the efficiency for removing the foreign materials and pyrolytic efficiency. CONSTITUTION:This pyrolytic furnace is obtained by installing a pyrolytic vessel and a hollow vertical rotating shaft 9 having a lower part immersed in a plastic melt in the pyrolytic vessel and a notch at the bottom of the peripheral wall, arranging a foreign material suction pipe 18 in the vertical rotating shaft 9, further providing a vacuum pump capable of sucking the foreign materials together with the plastic melt in the pyrolytic vessel through the foreign material suction pipe 18, fixedly installing stirring blades 15, protruding outward in the radial direction and curved toward the outside in the radial direction to the front in the rotative direction of the vertical rotating shaft 9 in the peripheral wall thereof and providing the stirring blades 15 with the shape of a curve changing from the outer peripheral surface side of the peripheral wall of the vertical rotating shaft 9 as a starting point so as to slowly reduce the curvature toward the tips when viewed from a plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for, for example, melting and thermally decomposing waste plastic, cooling and condensing the generated pyrolysis gas, and recovering it as pyrolysis oil.

[0002]

2. Description of the Related Art As one of the methods for thermally decomposing plastics as described above, the raw material plastics are melted in the pyrolysis vessel and at the same time thermally decomposed, and the gas generated by the thermal decomposition is generated. A method of recovering a light oil by sending it to a catalyst layer to decompose it into a low carbon chain hydrocarbon and then condensing it in a cooling and condensing section is practiced.

By the way, in such a method, most of the waste plastics used as raw materials are usually discharged as industrial wastes from plastic producers or as wastes separated. Therefore, foreign materials such as metal and glass are mixed in the raw material plastic. Such foreign matter is released into the melt during melting in the above method, and accumulates in the melt when the plastic is continuously pyrolyzed. The problem arises that the

Therefore, conventionally, in order to solve the above problem, the operation of the apparatus is intermittently stopped, and the accumulated foreign matter is removed after the apparatus is cooled to near normal temperature.

However, in such a method, the energy loss when the apparatus is cooled to near room temperature for removing the foreign matter and the energy loss required for the temperature rise until the restart after the foreign matter is removed are large, and the thermal decomposition is caused. There is a problem that the fuel consumption required for

Further, in order to perform the thermal decomposition of the plastic efficiently, it is necessary to make the temperature distribution of the plastic melt liquid uniform, but there is no means for making the temperature distribution of the plastic melt liquid uniform. Is the current situation.

An object of the present invention is to solve the above-mentioned problems, to remove foreign matter from the system without stopping the apparatus, to reduce energy loss when removing the foreign matter, and to melt the plastic during the work. An object of the present invention is to provide a thermal decomposition device for plastics, which can make the temperature distribution of the liquid uniform.

[0008]

In a thermal decomposition apparatus for plastics according to the present invention, a thermal decomposition vessel that melts and thermally decomposes the plastic inside, and a lower portion is immersed in a plastic melt in the thermal decomposition vessel. A hollow vertical rotary shaft having an upper part projecting above the pyrolysis tank and having internal and external foreign matter suction ports at its lower end, and a plastic melt inside the vertical rotary shaft and having its lower end in the pyrolysis tank. It is equipped with a foreign matter suction pipe that is immersed in the container and suction means that sucks and removes the foreign matter together with the plastic melt in the thermal decomposition vessel through the foreign matter suction pipe. A stirring blade that is curved forward in the direction of rotation of the vertical rotation shaft toward the outside in the fixed direction is provided in a fixed shape. It headed those which are varying curved shapes so gradually curvature decreases.

[0009]

According to the plastic thermal decomposition apparatus configured as described above, the foreign matter mixed in the plastic melt is generated by the centrifugal force by the action of the stirring blade when the vertical rotary shaft is rotated. It is collected in the vicinity of the vertical rotation axis in the pyrolysis vessel without being dispersed. Then, in a state where the foreign matter is collected in the vicinity of the vertical rotation axis, the foreign matter can be sucked and removed by the suction means through the foreign matter suction pipe together with the plastic melt in the thermal decomposition vessel. Further, when the vertical rotary shaft is rotated, the temperature distribution of the plastic melt becomes uniform due to the action of the stirring blade.

[0010]

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

1 and 2 show a plastic thermal decomposition apparatus according to the present invention.

In FIGS. 1 and 2, the plastic thermal decomposition apparatus comprises a thermal decomposition vessel (1) for melting and thermally decomposing the raw material plastic and a foreign matter collection container (2).

The pyrolysis pot (1) is arranged in a furnace (4) having a heating burner (3). The pyrolysis kettle (1) is circular when viewed from above, and the bottom surface is a concave spherical surface that is recessed downward. A feed pipe (5) for the raw material plastic and a discharge pipe (6) for the pyrolysis gas are connected to the lid (1a) of the pyrolysis pot (1). The supply pipe (5) is connected to the raw material hopper (8) via a valve (7). Waste plastic as a raw material is crushed and put in the raw material hopper (8). 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 kettle (1) through the discharge pipe (6) to the portion having the catalyst layer, where it is further decomposed by the catalyst,
Following this, it is sent to a cooling / condensing section where it is condensed and collected as light oil here.

A hollow vertical rotation shaft (9) is arranged so as to penetrate through the central portion of the lid (1a) of the pyrolysis pot (1). The vertical rotation shaft (9) is composed of an upper component (9a) and a lower component (9b) having a circular cross section, which is connected to the lower end of the upper component (9a) via a flange joint (10). A seal device (11) seals between the upper component (9a) of the vertical rotation shaft (9) and the periphery of the hole through which the rotation shaft (9) penetrates in the lid (1a). The lower end of the lower component (9b) of the vertical rotary shaft (9) is located near the bottom of the pyrolysis kettle (1). The upper part of the vertical rotation shaft (9) projects above the lid (1a), and the gears (12) (13)
It is connected to the drive motor (14) via.

The lower end of the peripheral wall of the lower component (9b) of the vertical rotary shaft (9) projects radially outward at a position symmetrical with respect to the center of rotation of the vertical rotary shaft (9), and radially outward. 2 towards the front in the direction of rotation of the vertical axis of rotation (9)
Two stirring blades (15) are fixedly provided. Each stirring blade (1
5) Rotation direction rear surface and vertical rotation axis (9) lower component
A rib (15a) is provided so as to straddle the peripheral wall of (9b). Each stirring blade (15) has a shape similar to a parabola whose top is a connecting portion with the outer peripheral surface of the vertical rotation axis (9) when seen in a plan view. As shown in Fig. 3, the center of rotation of the vertical rotation axis (9)
(O) and multiple points at intervals along the length of the stirring blade (15)
An angle formed by a line (X1) to (X5) connecting (P1) to (P5) and a tangent (Y1) to (Y5) at each point (P1) to (P5) of the stirring blade (15) ( It is preferable that θ1) to (θ5) are in the range of 25 to 30 degrees, respectively. Also the vertical axis of rotation (9)
At the lower end of the peripheral wall of the lower component (9b) of
A notch (16) (foreign substance suction port) is formed at a position forward of the base end of 5) in the rotational direction.

At a position slightly above the parabolic stirring blade (15) on the peripheral wall of the lower component (9b) of the vertical rotation shaft (9),
Two stirring blades (17), which are linear when viewed from a plane projecting radially outward, are fixedly provided. These stirring blades (17)
Are located on a straight line when viewed from above. When seen from a plane, the straight line connecting the tip ends of both parabolic stirring blades (15) and each straight stirring blade (17) form a substantially right angle. In addition, the rear surface of each stirring blade (17) in the direction of rotation and the vertical rotation axis (9)
Rib (17) so that it straddles the peripheral wall of the lower component (9b) of
a) is provided.

A foreign matter suction pipe (18) is arranged in the vertical rotation shaft (9). The lower end of the foreign matter suction pipe (18) is located slightly above the notch (16) in the peripheral wall of the lower component (9b) of the vertical rotation shaft (9). The upper end of the foreign matter suction tube (18) has a vertical rotation axis (9).
It extends above the upper end of and is connected to the foreign matter collection container (2) through a conduit (19). Foreign object suction tube (18) and conduit
A valve (20) is provided between the valve and (19). Vertical rotation axis
A seal device (21) seals between the upper end of (9) and the foreign matter suction pipe (18).

A vacuum pump (23) (suction means) is connected to the foreign matter collection container (2) via a valve (22). Normally the valve (22) is opened and the valve (20)
Is closed, and the vacuum pump (23) is operated so that the foreign matter collection container (2) including the conduit (19) is in a vacuum state.

In such a structure, waste plastic, which is a raw material mixed with foreign matter such as industrial waste, is
By opening (7), the raw material hopper (8) is supplied to the pyrolysis kettle (1) through the supply pipe (5). This raw plastic is heated by the combustion heat of the heating burner (3),
It is melted and becomes a melt (24). Here, in order to make the temperature distribution of the plastic melt (24) uniform and promote the reaction, the vertical rotation shaft (9) is rotated by the drive motor (13) in the directions shown by the arrows in FIGS. 2 and 3, The molten liquid (24) in the thermal decomposition pot (1) is stirred by stirring blades (15) (17). Melt (24)
Although it depends on the type of plastic, if it is maintained at 140 ° C or higher, a thermal decomposition reaction occurs and a thermal decomposition gas is generated.
The generated gas is mainly composed of hydrocarbon gas having 1 to 40 carbon atoms, and is sent to the portion having the catalyst layer through the discharge pipe (6), where it is further decomposed into low carbon chain hydrocarbons. After being cooled, it is sent to a cooling / condensing section, where it is cooled and condensed, and recovered as light oil.

If such an operation is continued, foreign matter (2) having a large specific gravity such as metal and glass mixed in the melt (24)
5) settles and collects at the bottom of the pyrolysis kettle (1). These foreign substances (25) are collected by the function of the parabolic stirring blade (15) in the central part of the bottom of the thermal decomposition vessel (1), that is, in the vicinity of the vertical rotating shaft (9), without being dispersed by centrifugal force. To be Therefore, when the valves (20) and (22) are opened and the vacuum pump (23) is operated, the foreign matter collection container (2) is evacuated, and the foreign matter ( 25) is the plastic melt
Along with (24), it enters the vertical rotary shaft (9) through the notch (16) of the lower component (9b) of the vertical rotary shaft (9), and further through the foreign matter suction pipe (18) and conduit (19). It is sucked into the foreign material collection container (2). Lower component with notch (16) on vertical axis of rotation (9)
Since the lower end of the peripheral wall of (9b) is formed at a position forward of the base end of each stirring blade (15) in the rotation direction, the stirring blade (1
The foreign matter (25) collected in the vicinity of the vertical rotation shaft (9) is smoothly introduced into the vertical rotation shaft (9) by 5). In this way, the foreign matter (25)
Are removed.

In the above embodiment, a parabolic stirring blade (15)
Is not present and only the linear stirring blade (17) is present,
The sedimented foreign matter is dispersed by centrifugal force.

In the above embodiment, the lower curved stirring blade (15) has a parabolic shape when viewed from the top, but when viewed from the top, it starts from the outer peripheral surface side of the peripheral wall of the vertical rotating shaft and faces the tip. The shape is not limited as long as it is a curved shape that gradually decreases in curvature. Further, in the above embodiment, the linear stirring blade is fixedly provided on the vertical rotating shaft in addition to the curved stirring blade, but the present invention is not limited to this, and only the parabolic stirring blade is fixedly provided. It may be. Further, in the above embodiment, the suction means is a vacuum pump, but the suction means is not limited to this, and a suction means composed of an ejector or a jet pump may be used.
Further, in the above embodiment, the foreign matter suction port is a notch formed at the lower end of the peripheral wall of the vertical rotation shaft, but the invention is not limited to this.

[0023]

According to the apparatus for thermally decomposing plastics of the present invention, as described above, it is possible to remove foreign substances mixed in the plastic melt. Therefore,
Since it is not necessary to stop the equipment and cool it to around room temperature,
Energy loss when removing foreign matter is reduced, and fuel consumption required for thermal decomposition is improved. Moreover, by the function of the stirring blade, the foreign matter mixed in the plastic melt is collected by the centrifugal force in the vicinity of the vertical rotating shaft in the thermal decomposition vessel without being dispersed, so that the foreign matter removal efficiency is improved. In addition, the temperature distribution of the plastic melt becomes uniform due to the function of the stirring blade when rotating the vertical rotation axis.
The efficiency of pyrolysis is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the overall configuration of a thermal decomposition apparatus according to the present invention.

FIG. 4 is a sectional view taken along line II-II in FIG.

FIG. 3 is a plan view showing a parabolic stirring blade.

[Explanation of symbols]

 (1) Thermal decomposition kettle (9) Vertical rotary shaft (15) Stirring blade (16) Notch (foreign matter suction port) (18) Foreign matter suction pipe (23) Vacuum pump (suction means) (24) Plastic melt

Claims (1)

[Claims] 1. A pyrolysis kettle for melting and thermally decomposing plastic inside, a lower portion immersed in a plastic melt in the pyrolysis kettle and an upper portion protruding above the pyrolysis kettle, and a lower end. A hollow vertical rotary shaft with internal and external foreign matter suction ports, a foreign matter suction pipe which is located in the vertical rotary shaft and whose lower end is immersed in the plastic melt in the thermal decomposition vessel, It is equipped with suction means that suctions and removes the foreign material together with the plastic melt in the disassembling kettle, projects radially outward on the peripheral wall of the vertical rotation shaft, and forwards in the direction of rotation of the vertical rotation shaft radially outward. A curved stirring blade is provided in a fixed shape, and the shape of the stirring blade changes from the starting point on the outer peripheral surface side of the peripheral wall of the vertical rotation axis when viewed from the plane and gradually decreases toward the tip. And Pyrolysis device for plastics.