JP2958607B2 - Quantitative extraction method of foreign substance-containing melt from waste plastic pyrolysis reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for melting and pyrolyzing waste plastic, cooling and condensing generated pyrolysis gas, and recovering it as pyrolysis oil. The present invention relates to a method of quantitatively withdrawing from a reactor.

[0002]

2. Description of the Related Art To treat waste plastics, most of general wastes are incinerated and landfilled, and some of them are reused as industrial wastes. As for the reuse of waste plastics, the use of waste plastics as fuel by thermal decomposition is being promoted. As one of the pyrolysis methods, waste plastic is melted in a pyrolysis reactor and pyrolyzed at the same time, and the gas generated by the pyrolysis is sent to the catalyst layer to be decomposed into low-carbon hydrocarbons, and then cooled and condensed. A method of recovering light oil by condensing in a section has been performed.

By the way, in such a method, waste plastic as a raw material is usually discharged from a plastic product producer as industrial waste or discharged as separated waste. Therefore, foreign materials such as metal and glass are mixed in the raw material waste plastic.
Such foreign substances are released into the melt at the time of melting in the above-described method, and accumulate in the melt when the waste plastic is continuously subjected to thermal decomposition treatment, thereby melting and thermally decomposing the waste plastic. Fill the reactor. Also, the coke of waste plastic accumulates in the reactor. As described above, if coking or foreign matter accumulates in the thermal decomposition reaction vessel, heat transfer to the reaction vessel deteriorates and decomposition of waste plastic is hindered, or the surface temperature of the outer wall of the reaction vessel becomes a heat resistant temperature. And continuous operation cannot be performed. In order to prevent this, it is necessary to remove caulk and foreign matter from the reaction vessel together with the high-temperature melt by a vacuum method.

In order to solve the above-mentioned problem, a pyrolysis reactor for melting and thermally decomposing waste plastics, and one end connected to the pyrolysis reactor and extracting a foreign substance-containing melt from the pyrolysis reactor. Heat of waste plastic comprising a foreign matter discharge pipe, a foreign matter collection vessel to which the other end of the foreign matter discharge pipe is connected, and pressure adjusting means for adjusting the pressure in the foreign matter collection vessel to below atmospheric pressure. cracker has been proposed (Japanese Patent
Kaihei 7-41773 ).

[0005]

When the melt is withdrawn from the pyrolysis reactor, a predetermined amount must be extracted with respect to the amount of waste plastic to be processed or the amount of melt in the reactor. Driving is impossible. In order to extract a certain amount of melt, it is necessary to stop the extraction when a predetermined amount is reached while measuring the extracted melt in a storage container.
Since the vacuum extraction line is of course a closed system, it is not possible to measure the weight with a load cell or the like with only the storage container disconnected. In addition, since a high-temperature melt enters the storage container, an expensive and special level meter such as an electromagnetic wave type is required to measure the melt level in the container.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a waste plastic pyrolysis and oiling apparatus having the above-described structure, wherein the level (discharged melt amount) in a container is detected by inexpensive means, and the discharged melt is reduced to a predetermined amount. It is an object of the present invention to provide a method for quantitatively withdrawing a foreign substance-containing melt from a waste plastic pyrolysis reactor, in which the withdrawal is stopped at the time when it becomes unnecessary.

[0007]

According to the present invention, there is provided a method for quantitatively extracting a foreign substance-containing melt from a pyrolysis reactor according to the present invention.
A foreign matter discharge pipe having one end connected to the pyrolysis reaction vessel and extracting a foreign substance-containing melt from the pyrolysis reaction vessel, a foreign matter collection vessel connected to the other end of the foreign matter discharge pipe, and a foreign matter collection pipe. Pressure adjusting means for adjusting the pressure in the collecting vessel to the atmospheric pressure or less, and the melt discharged from the reaction vessel to the foreign matter collecting vessel is provided in the same vessel.
Within a predetermined amount, and this signal
In the waste plastic pyrolysis device that controls the temperature of the melt and removes the foreign substance-containing melt , the fact that the melt discharged from the reaction vessel to the foreign substance collecting container has reached a predetermined amount in the same container ,
It is characterized by detecting with a temperature sensor .

After a certain amount of the foreign-material-containing melt is withdrawn into a foreign-matter collecting container, the suction system, that is, the foreign-matter collecting container and the piping around the container are replaced with an inert gas.

When the pressure in the foreign matter collecting container is adjusted to be lower than the atmospheric pressure by the pressure adjusting means, the melt in the pyrolysis reaction vessel and the foreign matter mixed therein are removed by the foreign matter discharging pipe. Then, it is sucked into the foreign matter collecting container.

[0010]

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 includes a pyrolysis reaction tank (1) for melting and thermally decomposing raw material waste plastic, and a foreign matter collecting container (2).

The pyrolysis reactor (1) is placed in a furnace (4) provided with a heating burner (3). The bottom of the pyrolysis reactor (1) has a concave spherical shape that is concave downward. A feed pipe (5) for raw material waste plastic and a discharge pipe (6) for pyrolysis gas pass through the lid (1a) of the pyrolysis reactor (1) and communicate with the top of the reactor (1). 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) to the portion having the catalyst layer via the discharge pipe (6), where it is further decomposed by the catalyst, and then to the cooling / condensing section. Sent and condensed, where it is recovered as light 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) extends to near the bottom of the pyrolysis reactor (1). A portion of the vertical rotation shaft (9) located above the lid (1a) is connected to a drive motor (13) via a gear (11) and a gear (12). 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 pyrolysis reactor (1).

A foreign matter suction pipe (15) is arranged in the vertical rotation shaft (9). The upper end of the foreign matter suction pipe (15) is a vertical rotation axis (9)
It extends above the upper end of the container, and is connected to a foreign substance collecting container (2) via a conduit (16). The outer jacket (25) and the bottom jacket (2)
6) is provided, and a dripping discharge pipe is provided at the center of the cone-shaped bottom wall.
The pipe (27) is provided with a filter (29) and a valve (V-2) below the filter (29). The discharge pipe (27) is heated by a heater (28) disposed therearound. A temperature sensor (TE) penetrates the top wall of the foreign matter collecting container (2) and is provided in a hanging manner, and a recorder (TR) is connected to the temperature sensor (TE).

A valve is provided between the foreign matter suction pipe (15) and the conduit (16).
(HV-2) is provided. The foreign matter suction pipe (15) and the conduit (16) constitute a foreign matter discharge pipe. Sealing device between the upper end of the vertical rotation shaft (9) and the foreign matter suction pipe (15)
Sealed by (18). The lower end of the foreign matter suction pipe (15) is located at substantially the same height as the lower end of the vertical rotation shaft (9).

A buffer tank (1) is provided in the foreign matter collecting container (2).
A vacuum pump (20) (pressure adjusting means) is connected via 9). A conduit (31) connecting the buffer tank (19) and the vacuum pump (20) is provided with a valve (HV-5). Vacuum pump
A conduit (24) for releasing (20) to the atmosphere is provided with a valve (V-1).

A conduit (23) having a valve (HV-1) is provided at the upper end of the foreign matter suction pipe (15) from the nitrogen cylinder (17), and the top of the foreign matter collecting container (2) is provided from the nitrogen cylinder (17). , Valve (HV-4)
A conduit (32) is provided. In the conduit (16), between the valve (HV-2) and the foreign matter collection container (2), the valve (H
A conduit (30) having V-3) is connected.

In such a configuration, the raw waste plastic mixed with foreign matter such as industrial waste is supplied to the pyrolysis reactor from the raw material hopper (8) through the supply pipe (5) by opening the valve (7). Supplied to (1). This raw material waste plastic is heated and melted by the heat of combustion of the heating burner (3) to form a melt (21). Here, in order to promote the reaction, the vertical rotation shaft (9) is rotated by the drive motor (13),
The melt (21) in the thermal decomposition reactor (1) is stirred by the stirring blade (14). The melt (21) undergoes a thermal decomposition reaction when maintained at 140 ° C. or higher, depending on the type of waste plastic, and generates a thermal decomposition gas. 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 cooling / condensing section, where it is cooled and condensed, and collected as light oil.

If such an operation is continued, foreign matter (22) such as metal and glass mixed in the melt (usually about 390 to 420 ° C.) accumulates in the pyrolysis reactor (1). Come.
Then, the foreign matter (22) having a high specific gravity, such as metal or glass, is formed on the bottom of the pyrolysis reactor (1) by the coagulation effect of the shape of the stirring blade (14) and the shape of the bottom of the pyrolysis reactor (1). It accumulates in the center. When the amount of accumulated foreign matter (22) increases,
Damage to the stirring blades (14) or melt at the bottom of the pyrolysis reactor (1)
The problem of scorching (21) occurs. In order to prevent this, as described below, the foreign matter-containing
Extract from (1).

First, the valve (HV-5) is opened, the valve (HV-2) is closed, and the vacuum pump (20) is operated, so that the suction system, ie, the vacuum pump (20)
From the container (2) to the valve (HV-2) including the foreign matter collecting container (2) were kept in a vacuum state.

Next, when the valve (HV-2) is opened,
At that moment, the vapor accumulated in the upper part of the foreign matter suction pipe (15) is sucked, and the pressure inside the pyrolysis reaction vessel (1) becomes atmospheric pressure (760).
mmHg), a pressure difference is generated between the pyrolysis reactor (1) and the foreign matter collecting container (2), and the melt (S) in the suction pipe (15) follows the suction of steam. 21) is sucked while flash evaporation occurs, and passes through the conduit (16) to the foreign matter collecting container (2).
Get in. The suction state at this time depends on the displacement of the vacuum pump (20), and is 500 liter / min.
When 10 liters of the melt (21) is sucked using the liquid, the melt (21) flash-evaporates at the moment when the valve (HV-2) is opened, and the pressure in the foreign matter collecting container (2) is increased. Is 0mmHg to 5
The temperature rises to 43 mmHg, and the melt (21) is deprived of latent heat of vaporization, and its temperature falls from 330 ° C. to 314 ° C. At this time, since there is still a pressure difference between the pyrolysis reactor (1) and the foreign matter collecting container (2), the melt (21)
Is sucked through the suction pipe (15) and the conduit (16) at a speed of 1.53 m / sec, and moves into the foreign substance collecting container (2). Then, to suck 10 liters of the melt before evaporation, 13.5
Takes seconds. Thus, the foreign matter (22) is removed from the reaction vessel (1) without stopping the operation of the thermal decomposition apparatus.

Next, a specific operation example performed using the apparatus shown in FIG. 1 will be described.

1. First, valve (HV-1), valve (HV-2),
Close the valve (HV-3), valve (HV-4) and valve (HV-5), turn off the vacuum pump (20), and check each line.

2. Next, the valve (HV-5) is opened, the vacuum pump (20) is turned on, and it is confirmed that the suction system is in a vacuum. Thus, a vacuum is created between the vacuum pump (20) and the valve (HV-2).

3. Close the valve (HV-5) and vacuum pump (20)
Turn off and confirm that the vacuum of the suction system is maintained. Thus,
A vacuum is maintained between valve (HV-5) and valve (HV-2).

4. Open the valve (HV-2). As a result, the coking material is scraped off by the foreign matter and stirring blades in the pyrolysis reaction vessel, and the waste plastic high-temperature melt (21) is vacuumed from the pyrolysis reaction vessel (1) to the foreign matter collection container (2). It is extracted. Thus, the withdrawal of the melt is started.

5. The melt remaining in the foreign matter collection container (2) reaches the tip of the temperature sensor (TE), and when the temperature indicated by the temperature sensor (TE) rises rapidly and reaches a predetermined temperature, the valve (HV-1) is opened. After opening for a few seconds, nitrogen gas is blown into the suction pipe (15) from the nitrogen cylinder (17). As a result, withdrawal of the melt at the top of the suction tube (15) is cut off. Next, the valve (HV-1) is closed.

6. Close the valve (HV-2) and stop withdrawing the melt.

7. Open the valve (HV-4) and open the nitrogen cylinder (17)
Nitrogen gas is blown into the foreign substance collection container (2) from the container. afterwards,
Close the valve (HV-2). Thus, the pressure between the valve (HV-2) and the valve (HV-5) is returned to the atmospheric pressure.

8. Open the valve (HV-2) and remove the residual melt between the valve (HV-2) and the foreign matter collecting container (2).
Drop.

9. Open the valve (HV-3) if necessary,
Clean the discharge line with cleaning oil. Then the valve
Close (HV-3).

10. Close the valve (HV-2) (No. 8 to No.
10 is a predetermined time), and disconnect the discharge line from the pyrolysis reactor (1).

11. The temperature sensor (TE) is used to confirm that the melt discharged in the foreign substance collecting container (2) is liquid and has dropped to a low temperature (110 to 200 ° C.).

12. Open the valve (V-1), then open the valve
(V-2) is opened, and the melt having passed through the filter (29) is discharged from the foreign substance collecting container (2). FIG. 2 shows an automatic sequence of the operation Nos. 4 to 6 described above. When the push button (PB) is pressed, the valve (HV-2) opens and the withdrawal of the melt from the pyrolysis reactor (1) starts. When the temperature indicated by the temperature sensor (TE) reaches the predetermined temperature, the temperature controller turns on and the valve
(HV-1) opens and the timer (T1) turns on. After a lapse of a predetermined time, the timer (T1) is operated, the valve (HV-1) is closed, the valve (HV-2) is closed, and the operation is restored by the timer (T2).

FIG. 3 shows the relationship between the pressure change and the temperature change in the foreign substance collecting container (2) when the melt is discharged.

With the above operation, five extraction tests were performed. 17.7k discharged melt in 5 tests
g, 17.0 kg, 17.3 kg, 17.1 kg and 17.5 kg.

In the above embodiment, a vacuum pump is used as the pressure adjusting means, but the present invention is not limited to this. For example, after the system connected to the foreign matter collection container is first evacuated, the foreign matter collection container is cooled, and the inside of the system in which enough gas is condensed to be exhausted by the vacuum pump is maintained at a constant pressure. A pressure adjusting means for maintaining the pressure may be used. The nitrogen gas is used as the purge gas in order to prevent combustion of the decomposition gas of the waste plastic. An inert gas such as carbon dioxide can be used instead of nitrogen gas.

[0038]

According to the present invention, in a waste plastic pyrolysis / oiling apparatus, the level in the tank (the amount of the melt to be withdrawn) is detected by an inexpensive method, and when the amount of the withdrawn melt reaches a predetermined amount, the withdrawal is performed. Can be stopped, so that the waste plastic pyrolysis / oiling device can be operated constantly.

[Brief description of the drawings]

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

FIG. 2 is a graph showing an automatic sequence of operations No. 4 to No. 6;

FIG. 3 is a graph showing a relationship between a pressure change and a temperature change in a foreign substance collecting container (2) when a melt is discharged.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pyrolysis reactor 2 Foreign substance collection container 17 Nitrogen cylinder 20 Vacuum pump (pressure adjusting means) TE Temperature sensor HV-1 valve HV-2 valve HV-3 valve HV-4 valve HV-5 valve

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshio Hama 5-3-28 Nishikujo, Konohana-ku, Osaka Nichichi Shipbuilding Co., Ltd. (56) References JP-A-6-116567 (JP, A) JP-A-6-206058 (JP, A) JP-A-6-136368 (JP, A) JP-B-56-22688 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) C10G 1 / 10 B09B 3/00 C10J 3/00 C08J 11/12

Claims (1)

(57) [Claims] 1. A pyrolysis reaction vessel for melting and thermally decomposing waste plastic, a foreign matter discharge pipe connected at one end to the pyrolysis reaction vessel and for discharging a foreign substance-containing melt in the pyrolysis reaction vessel, comprising a foreign matter collecting container to which the other end of the foreign matter discharge pipe is connected, and a pressure adjusting means for adjusting the pressure of the foreign matter collecting vessel below atmospheric pressure, the foreign matter collecting container from the reaction kettle
Check that the amount of melt discharged to
The signal is used to control the valve to control the melt containing foreign matter.
In the waste plastic pyrolysis apparatus for stopping the withdrawal , a temperature sensor detects that the amount of the melt withdrawn from the reaction vessel to the foreign matter collecting container has reached a predetermined amount in the container, A method for quantitatively extracting a foreign substance-containing melt from a waste plastic pyrolysis reactor.