JP2003183671A - Waste plastic decomposition oil-recovering equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recover a large amount of a thermal decomposition oil, while avoiding the clogging of a flow passage due to the coagulation, when a thermal decomposition product of waste plastics is cooled, and to separate and recover a heavy oil and a light oil with a simple installation. <P>SOLUTION: This waste plastic decomposition oil-recovering equipment for thermally decomposing waste plastic and then cooling and condensing the produced gaseous thermal decomposition product to recover the decomposition oil is characterized by carrying out the cooling and condensing operations with a reflux condenser and forming a decomposition oil-recovering tank in the bottom portion of the condenser. The recovering tank is divided into upper and lower chambers with a tank-like partition member having vent holes, and a pipe for introducing the thermal decomposition product into the condenser is connected to the lower chamber. the heavy oil and light oil are separated in the lower and upper chambers, respectively, and recovered. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for thermally decomposing waste plastics and recovering decomposed oils in order to reuse the waste plastics.

[0002]

2. Description of the Related Art A method and apparatus for thermally decomposing waste plastic as described above and recovering it as decomposed oil have been known for a long time. For example, as shown in FIG. 1, a heating furnace 3 which is usually filled with waste plastic 2 in a pyrolysis tank 1 and equipped with a burner 4
And the like, and the gaseous thermal decomposition product generated by this is decomposed by heating using a heating means such as
It is stored in the recovery tank 7 after being led to, cooled and condensed into decomposed oil.

In such a conventional apparatus for recovering decomposed oil of waste plastic, there are the following inconveniences and points for improvement when recovering decomposed oil. Some decomposed oil of waste plastic solidifies at around room temperature. For example,
It is known that the decomposition oil of polyethylene solidifies into a wax at 30 to 50 ° C, and when the thermal decomposition product of waste plastic containing polyethylene is cooled with a heat exchanger, etc. May solidify and clog the pipes, which may cause inconvenience in collecting the decomposed oil. The clogging of the pipe due to the thermal decomposition products is one of the most dangerous conditions in operating the cracked oil recovery device. In order to avoid this inconvenience, it is conceivable that a temperature control mechanism is provided in the heat exchanger so that the temperature of the thermal decomposition product can be maintained at 50 ° C. or higher, but the equipment cost becomes high and the Monitoring is required, which is not desirable.

Further, in general, cracked oil of plastic contains components having a wide boiling range. Fig. 2 shows an example of carbon number distribution of the decomposed oil of plastic.
-30 components are included, and if this is adjusted to the boiling point range, -0.5 to 4
Corresponds to 55.9 ° C. If cracked oil with such a wide boiling range is treated as a single product oil, many constituents are kerosene-equivalent components, and even if cracked oil with an average property close to kerosene, gasoline content is also included in it. Since it is included, the flash point will be less than 21 ° C, which causes the inconvenience of being treated as No. 1 petroleum under the Fire Service Law. It is considered that this inconvenience can be solved by dividing the cracked oil into light oil and heavy oil, consuming the light oil as fuel for the recovery device and recovering the heavy oil as product oil. In this case, it is preferable to divide the cracked oil into light oil and heavy oil by using a simpler means without separately preparing distillation equipment.

[Problems to be Solved by the Invention]

The present invention is a device for recovering cracked oil of plastics, which is capable of sufficiently cooling the cracked oil and recovering as much cracked oil as possible, and the cracked oil produced when cooled excessively. It is possible to provide a recovery device that can avoid clogging of pipes due to the solidification of oil, and to separate heavy oil and light oil with different uses for recovery, and as simple as possible without adding distillation equipment. It is an object of the present invention to provide a recovery device that can perform the separation operation in equipment.

[Means for Solving the Problems]

In the present invention, there is provided a so-called waste plastic decomposed oil recovery apparatus for recovering decomposed oil by thermally decomposing waste plastic in a decomposition tank and cooling / condensing a gaseous thermal decomposition product generated along with the decomposition. In this case, the cooling / condensing operation is performed by a reflux condenser, and the bottom of the reflux condenser is configured as a recovery tank for the cracked oil. With this configuration, the thermal decomposition product falls along the cooling surface at the stage of the liquid material before solidification and is collected in the recovery tank at the bottom, so that the pipe is clogged due to the solidification of the thermal decomposition product. Does not occur. The recovery tank is divided into upper and lower chambers by a tank-shaped partition having a ventilation hole, and a pipe for guiding the thermal decomposition product from the decomposition tank to the reflux condenser is connected to the lower chamber to provide the thermal decomposition product. Of the above components, a component that has already flowed in a liquid state inside the pipe, that is, a heavy oil component, is recovered in the lower chamber, and a component that flows in as a gaseous substance from the pipe is passed through the vent hole to the reflux condenser. Of the gaseous matter, which was condensed by a reflux condenser into a liquid state, that is, a light oil component was collected in the upper chamber so that the light oil and the heavy oil could be taken out separately. . By dividing the cracked oil recovery tank into two chambers, the cracked oil can be easily separated and collected into heavy oil and light oil.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will be described with reference to the drawings. In FIG. 3, reference numeral 1 denotes a batch-type decomposition tank containing waste plastic 2, and the waste plastic 2 is thermally decomposed by heating the decomposition tank 1 by a burner 4 provided in a heating furnace 3. Gaseous thermal decomposition products are generated inside the decomposition tank 1. A pipe 5 is provided above the decomposition tank 1, and a thermal decomposition product generated inside the decomposition tank 1 is guided to a reflux condenser 9 having a recovery tank 7 at the bottom. Among the thermal decomposition products, the components that have become liquid due to natural cooling while passing through the pipe 5 fall into the recovery tank as they are, but the components that flow in the gaseous state to the reflux condenser 9 as they are. Then, most of the thermal decomposition products are condensed by the cooling there to become a liquid substance, which flows along the wall surface and flows down to the recovery tank. The liquid substance that has flowed down and accumulated in the recovery tank 7 is recovered as decomposed oil. In the embodiment of the present invention, the reflux condenser uses a vertically arranged multitubular heat exchanger, in which cooling water flows on the shell side and thermal decomposition products flow on the tube side. Further, the reflux condenser 9 and the recovery tank 7 at the bottom thereof are joined by a flange 14.

Further, a component which does not condense upon cooling in the reflux condenser 9 but passes through in a gaseous state, that is, a decomposed gas is taken out to the outside through a water sealing tank 8 made of a transparent resin which is connected through a connecting pipe 10. Or burner 4
Is used as a heat source for the decomposition tank 1 of this recovery device. If the water sealing tank is made of a transparent resin material, it is convenient because the flow state of the gas can be seen from the outside and the clogging of the pipe can be surely judged.

In the embodiment of the present invention shown in FIG. 4, when the gaseous thermal decomposition product produced by thermally decomposing the waste plastic 2 is cooled by the reflux condenser 9 and the decomposed oil is recovered, A device for separating and collecting heavy oil and light oil is shown. The conventional apparatus shown in FIG. 1 cannot separate and recover the thermal decomposition products into light oil and heavy oil. Also in Example 1 of the present invention shown in FIG. 3, the components of the thermal decomposition products that have already flowed in the pipe as a liquid, that is, heavy oil, and the gaseous products of the thermal decomposition products. The components that are flowed in as they are are cooled / condensed by the reflux condenser and are refluxed to be recovered, that is, the light oil is recovered without distinction in the same recovery tank. However, in the second embodiment of the present invention, As shown in FIG. 4, the bottom space of the reflux condenser 9, that is, the recovery tank 7 is divided into two upper and lower chambers 7a and 7b by a tank-shaped partition 11 having a vent hole 13, and the thermal decomposition product is decomposed into a decomposition tank. 1 to the reflux condenser 9
The pipe 5 leading to the lower chamber 7b is connected to recover a component of the thermal decomposition product that has already flowed in a liquid state in the pipe, that is, heavy oil, into the lower chamber 7b, and Of the decomposition products, the components that flow in as gaseous substances are used as the ventilation holes 13
The cracked oil is separated into light oil and heavy oil by collecting in the upper chamber 7a the component that is led to the reflux condenser 9 via the reflux condenser 9 and cooled / condensed to become a liquid substance and is refluxed. It was possible to collect separately. By dividing the cracked oil recovery tank section 7 configured at the bottom of the reflux condenser into two upper and lower chambers in this way, it is possible to easily separate and recover cracked oil into heavy oil and light oil without relying on distillation equipment or the like. You can Also, if cracked oil is separated into heavy oil and light oil and collected, then both oils are mixed in the correct ratio,
It is possible to provide recovered oil having a uniform flash point.

A pipe 5 for introducing a thermal decomposition product from the decomposition tank 1 to the reflux condenser 9 is connected to a lower chamber 7b in a state of being inclined downward from the middle. Therefore, the thermal decomposition product becomes a gas-liquid mixed phase state of 150 to 350 ° C. due to a temperature drop due to heat radiation or the like in the middle of the pipe 5, and the lower chamber 7b,
That is, it flows into the heavy oil recovery tank. Therefore, 30 to 80% of the thermal decomposition product is recovered as heavy oil in the lower chamber 7b.

As shown in FIG. 4, the partition 11 for vertically dividing the cracked oil recovery tank located in the bottom space of the reflux condenser 9 according to the second embodiment of the present invention has a recess for the liquid pool, as shown in FIG. Upper and lower two chambers 7 around it
It was composed of a tank-shaped container having a vent hole 13 communicating with a and 7b. By doing so, the thermal decomposition products that flow into the lower chamber 7b that defines the cracked oil recovery tank through the pipe 5 partially remain in the gaseous state and are discharged upward through the ventilation holes 13. Although it flows into the chamber 7a, the gaseous component is cooled by the reflux condenser 9 located further above, and a part of it is condensed and returned to the chamber 7a above and is recovered as light oil. The collected light oil has a structure that can be taken out to the outside through the pipe 12 connected to the upper chamber 7a, that is, the bottom of the light oil recovery tank. Similarly, the heavy oil is supplied to the lower chamber 7b, that is, the pipe 15 connected to the heavy oil recovery tank.
It is taken out via.

Further, a preferred embodiment of the present invention will be described in detail with reference to FIG. A chamber 7a above the cracked oil recovery tank 7,
That is, the upper edge of the light oil recovery tank was detachably attached to the main body flange 14 of the reflux condenser 9.
The temperature of the heavy oil recovered in the lower chamber 7b, that is, the heavy oil recovery tank is usually 150 to 250 ° C., which serves as a heat source to raise the temperature inside the light oil recovery tank 7a and accumulate it. In order to prevent the light oil from evaporating again, the light oil recovery tank
By providing a cooling member inside 7a, it is possible to prevent evaporation of the recovered light oil due to reheating.

Furthermore, among the thermal decomposition products, they do not condense despite cooling in the reflux condenser 9,
A component that passes in a gaseous state, that is, a decomposed gas is guided to a water sealing tank 8 made of a transparent resin through a connecting pipe 10. The cracked gas that has passed through the water sealing tank 8 is sent to the flare stack and burns, or is guided to the burner 4 and used as a system internal fuel for the heating source of the cracking tank.

A branch pipe 18 is provided in the pipe 12 for extracting the light oil from the light oil recovery tank 7a to the outside, and a part of the light oil is supplied to a valve 19
It was returned to the heavy oil recovery tank 7b by the above operation so that it can be mixed with the heavy oil and recovered. This makes it possible to adjust the quantitative relationship between the two oils and prepare a recovered oil having an optimum flash point.

Further, in order to detect the amount of cracked oil remaining in the light oil recovery tank 7a, a pipe 12 for extracting light oil from the recovery tank 7a to the outside is branched and connected to the upper portion of the recovery tank 7a. A pipe 16 was provided, and a transparent pipe oil level gauge 17 was provided in the middle thereof. By doing so, the amount of light oil can be accurately measured, which is convenient.

[0016]

EXAMPLES (Prior art example) With the conventional apparatus configuration of FIG.
Then, 10 kg of polyethylene waste plastic was charged and the inside of the thermal decomposition tank 1 was heated to 450 ° C. to generate a thermal decomposition product. The temperature of the thermal decomposition product was about 310 ° C. at the position of the pipe 5, but when it was lowered to about 30 ° C. by the heat exchanger 6, condensation of the thermal decomposition product near the outlet of the heat exchanger was observed. The pipe was clogged due to solidification. After that, a pressure increase in the thermal decomposition tank due to the clogging was observed, so the operation was interrupted when about 5 kg of polyethylene decomposition oil had accumulated. After the operation was stopped, the heat exchanger 6 was opened and inspected, and it was found that a wax-like substance blocked the flow path near the outlet.

(Embodiment 1) In the apparatus constitution of the present invention shown in FIG. 3, 10 kg of polyethylene as waste plastic 2 is charged into the thermal decomposition tank 1 and the inside of the thermal decomposition tank is heated to 450 ° C. to generate a thermal decomposition product. It was The temperature of the thermal decomposition product was about 310 ° C. at the position of the pipe 5, and it flowed into the reflux condenser 9 as it was. The temperature of the decomposed gas measured near the outlet of the reflux condenser was about 30 ° C, and the temperature of the decomposed oil accumulated in the recovery tank 7 was about 150 ° C, but the reflux condenser was not clogged. It was Therefore, the operation continued without interruption, and the thermal decomposition was completed in about 4 hours. When weighed after the operation, the solid residue remaining in the thermal decomposition tank 1 was 0.1 kg, and the cracked oil accumulated in the recovery tank was
It was 8.4 kg, and the remaining 1.5 kg was decomposed gas. The flash point of the cracked oil was less than 21 ° C.

(Example 2) In the apparatus constitution of the present invention shown in FIG. 4, 10 kg of polyethylene as waste plastic 2 was charged into the thermal decomposition tank 1 and the inside of the thermal decomposition tank was heated to 450 ° C. to generate a thermal decomposition product. When the temperature of the thermal decomposition product was about 310 ° C. at the position of the pipe 5, it flowed into the lower chamber 7b defining the cracked oil recovery tank as it was, and 5.1 kg of the thermal decomposition product was converted to heavy oil. Recovered. Further, the thermal decomposition products other than the heavy oil flow into the upper chamber 7a through the vent holes 13 in a gaseous state,
Components cooled and condensed by the reflux condenser 9
3.7 kg was recovered as light oil in the upper chamber 7a. The decomposition gas was 1.1 kg and the decomposition residue was 0.1 kg. The flash point of the heavy oil was measured and found to be 28 ° C.

(Embodiment 3) With the apparatus constitution of the present invention shown in FIG. 4, 4 kg of polyethylene, 3 kg of polypropylene and 3 kg of polystyrene are charged as waste plastic 2 into the thermal decomposition tank 1 and the inside of the thermal decomposition tank is heated to 430 ° C. to heat it. When the cracked products were generated, the temperature of the cracked products became about 280 ° C. at the position of the pipe 5 and flowed into the lower chamber 7b which partitioned the cracked oil recovery tank as it was, and the temperature of the cracked products was 6.8%. kg was recovered as heavy oil. Further, the thermal decomposition products other than the heavy oil flow into the upper chamber 7a through the ventilation holes 13 in the gaseous state, and 2.3 kg of the components cooled and condensed by the reflux condenser 9 are stored in the upper chamber 7a as the light oil. Was recovered as. The decomposition gas was 0.8 kg, and the decomposition residue was 0.1 kg. The flash point of the heavy oil was measured and found to be 25 ° C.

[0020]

INDUSTRIAL APPLICABILITY As described above, in the present invention, so-called waste plastic is used, in which waste plastic is heated and decomposed in a decomposition tank, and gaseous pyrolysis products generated thereby are cooled and condensed to recover decomposed oil. In the cracked oil recovery apparatus of No. 1, the cooling / condensation operation is performed by a reflux condenser, and the bottom of the reflux condenser is configured as a recovery tank for the cracked oil, so that Clogs will not occur and safe operation can be secured. The recovery tank is divided into upper and lower chambers by a tank-shaped partition having a ventilation hole, and heavy oil is collected in the lower chamber and light oil is collected in the upper chamber, thereby decomposing oil of waste plastic. Light oil and heavy oil can be easily separated and taken out separately, and there is no need to install distillation equipment, and the equipment is cheap.

[Brief description of drawings]

FIG. 1 is an explanatory view of a conventional cracked oil recovery device.

FIG. 2 is an explanatory diagram of an example of carbon number distribution of recovered cracked oil.

FIG. 3 is an explanatory diagram of an embodiment of the device of the present invention.

FIG. 4 is an explanatory view of a modified example of the device of the present invention.

FIG. 5 is an explanatory view of another modification of the device of the present invention.

[Explanation of symbols]

1: Pyrolysis tank, 2: Waste plastics, 3: Heating furnace, 4:
Burner, 5, 10, 16, 18: Connection piping, 6: Cooling means,
7: cracked oil recovery tank, 7a: upper chamber, 7b: lower chamber,
8: Water sealing tank, 9: Reflux condenser, 11: Partition, 12, 15: Piping for extracting generated oil to the outside, 13: Vent hole, 14: Flange joint part, 17: Liquid level gauge, 19: Valve

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4D076 AA07 AA13 AA15 AA22 AA23                       AA24 BC01 BC21 BC25 BC27                       CB05 CB06 DA02 DA28 HA03                       JA01 JA03 JA04 JA05                 4F301 AA13 CA09 CA25 CA26 CA41                       CA51                 4H029 CA12

Claims (4)

[Claims] 1. An apparatus for recovering decomposed oil by thermally decomposing waste plastics in a decomposition tank and cooling and condensing a gaseous thermal decomposition product generated along with the decomposition of the waste plastics. An apparatus for recovering decomposed oil of waste plastic, wherein the apparatus is a flux condenser and the bottom of the reflux condenser is configured as a tank for recovering the decomposed oil. 2. The recovery tank is divided into upper and lower chambers by a tank-shaped partition having a vent, and a pipe for guiding the thermal decomposition product from the decomposition tank to the reflux condenser is connected to the lower chamber. Of the pyrolysis products, the heavy oil component that has already flowed in a liquid state in the pipe is recovered in the lower chamber, and the component that flows in as a gaseous substance from the pipe is refluxed through the vent hole. It is characterized in that a light oil component which is led to a condenser and condensed in a reflux condenser to become liquid among the gaseous substances is collected in the upper chamber to separately collect the light oil and the heavy oil. The apparatus for recovering decomposed oil of waste plastic according to claim 1. 3. The component of the decomposed gas that passes through in a gaseous state without being condensed by the reflux condenser is taken out to the outside through a water sealing tank made of a transparent resin. Equipment for decomposing oil from waste plastic. 4. The opening / closing door is provided on one side of the decomposition tank, and a tray for receiving the decomposition residue of the waste plastic is provided inside the decomposition tank so that the tray can be freely taken in and out. Oil recovery device for waste plastics.