JPH10237460A - Simple process for converting waste plastic into oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple process for converting waste plastics into an oil, whereby the yields of the oil formed from the plastics are high, and the equipment is simple. SOLUTION: Waste plastics together with a hydrocarbon oil being a solvent is introduced into a single treatment tank 13, the waste plastics and the hydrocarbon oil are heated in the tank 13 to dissolve the polyethylene, polypropylene band polystyrene in the waste plastics in the hydrocarbon oil and to produce a heat decomposition oil. On the other hand, the hydrocarbon oil contained in the residue withdrawn from the tank 13 after the heat decomposition is separated in a solid/liquid separation tank 14, and the separated hydrocarbon oil is used as the solvent introduced in the tank 13, and the residue left after the separation of the hydrocarbon oil is used as a heat source in the system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for converting waste plastics to oil, which can produce low-boiling hydrocarbon oils from waste plastics.

[0002]

2. Description of the Related Art The present applicant has previously filed Japanese Patent Application No. Hei 7-24801.
In No. 6, a method for recovering polyethylene, polypropylene and polystyrene by mixing a waste plastic material and an extraction solvent composed of hydrocarbon oil was presented. FIG. 3 shows the entire configuration of a waste plastic oil treatment plant C that can be suitably used in the method according to the present invention.

[0003] As shown in the figure, in this method, first, a waste plastic material in the form of a crushed product, a fluff or a crushed product is prepared by adding a hydrocarbon oil as a solvent heated to a temperature of 100 ° C to 200 ° C. The mixture is supplied into the raw material mixing tank 51 and mixed with stirring. By this operation, only polyethylene, polypropylene and polystyrene in the waste plastic material,
Since it has a relatively low melting point compared to other plastics and liquefies at 100 ° C. or higher, it is easily dissolved in hydrocarbon oil. On the other hand, since other plastics do not reach the melting point, they remain solid without liquefaction and are hardly dissolved.

[0004] Thereafter, the plastic melt produced by mixing and stirring is sent to a separation tank 52,
Remove insoluble components such as vinyl chloride, PET (polyethylene terephthalate) and metal from the plastic melt,
A plastic solution consisting of the produced oil and dissolved components is extracted. The plastic solution extracted in this way is supplied to the cracking distillation column 53 of the oil-treating section comprising the thermal decomposition section and the distillation section.
And the plastic solution is pyrolyzed. Note that a pyrolysis oil heating furnace 54 and a residue processor 55 are connected to the cracking distillation column 53. The pyrolysis gas generated by the pyrolysis in the pyrolysis section of the cracking distillation column 53 is separated by distillation into an aromatic fraction, a kerosene / light oil fraction, and a wax fraction by the distillation section of the cracking distillation column 53. Used as a product such as light oil. Further, the obtained oil is used as a fuel or as a hydrocarbon oil used in the extraction step by blending in the receiving tank 56.

[0005]

However, the above-mentioned methods for recovering polyethylene, polypropylene and polystyrene still have the following problems to be solved. That is,
In the above-described method, components more suitable for oiling than waste plastic material to be treated, that is, polyethylene, polypropylene and polystyrene are used to remove insoluble components from a plastic melt dissolved in a hydrocarbon oil as a solvent. In this step, the amount of the hydrocarbon oil remaining as the solvent in the insoluble matter is still large, which results in a loss, resulting in a decrease in the yield of the produced oil. In addition, in order to treat hydrocarbon oil as a solvent remaining in the insoluble matter in the system, a separate treatment device is required, and the equipment cost of the waste plastic oil treatment equipment C increases.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is possible to increase the yield of oil produced from waste plastics and to simplify the waste plastic oil processing equipment by simplifying waste plastic oil treatment equipment. It is an object to provide a chemical treatment method.

[0007]

According to the present invention, there is provided a semiconductor device comprising:
The method for converting a waste plastic into a simple oil is described, the waste plastic is put into a single treatment tank together with a hydrocarbon oil as a solvent, and the waste plastic and the hydrocarbon oil are heated in the treatment tank. Polyethylene, polypropylene and polystyrene in the waste plastic are eluted into the hydrocarbon oil, and the eluted polyethylene, polypropylene and polystyrene are thermally decomposed together with the hydrocarbon oil, and are produced by taking out and condensing as pyrolyzed oil vapor. While producing oil, the residue after the thermal decomposition is taken out of the treatment tank, the hydrocarbon oil contained in the residue is separated, and the separated hydrocarbon oil is put into the treatment tank together with the waste plastic. It is used as a solvent to be charged, and the residue after the hydrocarbon oil is separated is used as a heat source in the system. It has to.

According to a second aspect of the present invention, there is provided a method for simplifying the processing of waste plastic according to the first aspect, wherein the residue after the hydrocarbon oil is separated is partially burned. It is gasified by gasification or dry distillation, and this gas is collected and used in the system as the heat source.
The simple oil processing method of waste plastic according to claim 3 is:
In the method for easily converting waste plastic to oil according to claim 1 or 2, chlorine contained in the waste plastic is also removed in the single treatment tank.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. With reference to FIG. 1, a description will be given of a simplified method for converting waste plastic to oil according to an embodiment of the present invention.

First, with reference to FIG. 1, a waste plastic oil treatment equipment A to which the simple waste oil treatment method according to the present embodiment can be applied will be described. As shown in the figure, in the present embodiment, the waste plastic oil treatment equipment A includes a pretreatment equipment 10 and a pyrolysis oil treatment equipment 11. The pretreatment equipment 10 includes a primary crusher (not shown), a belt separator, a wind separator, a secondary crusher, a waste plastic receiving tank, and the like. It has a screw conveyor 12 for feeding. On the other hand, the thermal cracking and oiling equipment 11 is substantially a processing tank comprising a single extruder, a raw material mixing tank 51, a separation tank 52, and a single tank corresponding to the hydrogen chloride remover described with reference to FIG. 13, a solid-liquid separation tank 14, a distillation tower 15, and a generated oil storage tank 16.

The structure of the processing tank 13 will be further described. As shown in FIG.
Are provided concentrically and rotatably, and the stirrer 1
Reference numeral 7 denotes a rotary motor 1 mounted on the top of the processing tank 13.
8 is driven to rotate. At the top of the processing tank 13, a raw material inlet 19 is provided. Through the raw material supply pipe 19a and the raw material inlet 19, waste plastic from the screw conveyor 12 and a generated oil partial reflux pipe 25 described later are provided.
And a hydrocarbon oil as a solvent refluxed through the mixture can be charged into the treatment tank 13 in a mixed state.

At the top of the processing tank 13, a pyrolysis oil vapor outlet 20, a hydrogen chloride gas outlet 21, and a steam outlet 22 are further provided. The pyrolysis oil vapor outlet 20 is connected to the inlet of the distillation tower 15 by a vapor transfer pipe 23, and the distillation tower 15 is connected to the inlet of the generated oil storage tank 16 by a generated oil transfer pipe 24. I have. The other end of the generated oil partial reflux pipe 25, which is connected at one end to a middle part of the generated oil transfer pipe 24, is connected to the middle part of the raw material supply pipe 19a. The hydrogen chloride gas outlet 21 is connected to an inlet of a neutralization tank 27 by a hydrogen chloride gas transfer pipe 26, and the outlet of the neutralization tank 27 is open to the atmosphere. The steam outlet 22 is communicated with the atmosphere via a steam outlet pipe 28.

On / off valves 29, 30, and 31 are attached to the vapor transfer pipe 23, the hydrogen chloride gas transfer pipe 26, and the steam extraction pipe 28, respectively. A solid-liquid separation tank 14 composed of a centrifugal separator or the like is attached to a residue extraction pipe 32 led out from the bottom of the processing tank 13.
An on-off valve 33 is mounted in the middle of 2. In the lower part of the solid-liquid separation tank 14, a residue outlet 34 and a separated oil outlet 3
5 is provided, and the residue outlet 34 is provided with a residue transfer pipe 3.
6, it is connected to an inflow port of a gasifier 37 (for example, a rotary kiln, a screw-type dry distillation section, etc.). At the discharge port side of the gasifier 37, a decomposition gas extraction pipe 38 is provided.
Is connected to the pyrolysis oil heating furnace 40 for heating the waste plastic and the solvent in the processing tank 13. On the other hand, the separated oil outlet 35 is connected to the middle of the raw material supply pipe 19a via the pyrolysis oil reflux pipe 41.

Next, a simple method for converting waste plastic into oil using the waste plastic oil treatment equipment A having the above-described configuration will be described with reference to FIGS. 1 and 2. FIG. As shown in FIG.
The waste plastic supplied to the pyrolysis oil conversion equipment 11 is mixed with hydrocarbon oil as a solvent having the same weight ratio that has been refluxed from the generated oil partial return pipe 25 or the pyrolysis oil return pipe 41 and then mixed. , Into the processing tank 13. Then, in the treatment tank 13, the waste plastic and the hydrocarbon oil as the medium are heated by the pyrolysis oil heating furnace 40 as shown in FIG. That is, the waste plastic and the hydrocarbon oil are sequentially subjected to a dehydration / drying step 42 having different heating temperatures and heating times, a dechlorination step 43, a thermal decomposition / oiling step 44, and a residue discharging step 45. After that, heat treatment is performed as described below.

First, in the dehydration / drying step 42, the waste plastic and the hydrocarbon oil are mixed by the stirrer 17 for 1 to 3 hours.
Stir at a temperature between 0 ° C and 200 ° C. Accordingly, water is removed from the agitated object as water vapor, and the water vapor is released into the atmosphere through the water vapor extraction pipe 28 by opening the on-off valve 31. Note that the lower limit of the heating temperature is 1
The reason for setting the temperature to 00 ° C. is that the boiling point of water is 100 ° C.,
The upper limit of the heating temperature was set to 200 ° C. because a small amount of chlorine began to be generated by decomposition of polyvinyl chloride,
This is because the chlorine treatment is performed in the dechlorination step 43 which is the next step.

Next, in a dechlorination step 43, the waste plastic and the hydrocarbon oil are mixed with the stirrer 17 for 1 to 3 hours at 200 ° C.
The mixture is stirred at a temperature of about 350 ° C. to decompose polyvinyl chloride in the waste plastic and to remove hydrogen chloride gas from the material to be stirred. Thereafter, by opening the on-off valve 30, the hydrogen chloride gas is sent to the neutralization tank 27 through the hydrogen chloride gas transfer pipe 26, is rendered harmless by neutralization, and is released into the atmosphere. Therefore, it is possible to reduce the amount of chlorine remaining in the residue described below,
Even when the residue is incinerated and gasified, the equipment cost of the gas processing equipment can be reduced. Note that the lower limit of the heating temperature is 2
The reason why the temperature was set to 00 ° C. is to increase the dechlorination efficiency by generating a predetermined amount or more of hydrogen chloride, and the upper limit of the heating temperature was set to 350 ° C. This is because the temperature is close to the starting temperature.

Next, in the pyrolysis / oiling step 44, the chlorine-removed material to be stirred is stirred for 380 hours for 1 to 4 hours.
The waste plastic from which chlorine has been removed is thermally decomposed by stirring at a temperature of from 450C to 450C to generate pyrolysis oil vapor.
At this time, carbon is generated along with the thermal decomposition. However, since the carbon is dispersed in the thermal decomposition oil, the operation is not hindered. The reason why the lower limit of the heating temperature is set to 380 ° C. is to secure a thermal decomposition rate of a predetermined value or more and to efficiently perform thermal decomposition and oiling, and the upper limit of the heating temperature is set to 450 ° C. At the above temperature, the heating temperature is too high, and the amount of carbon deposition increases, which is a problem in operation and lowers the thermal efficiency.

The pyrolysis oil vapor is supplied to a vapor transfer pipe 2
3 and sent to the distillation column 15 for distillation. The heavy oil and light oil separated by distillation are separated from the heavy oil transfer pipe 24A,
The light oil is transferred to and stored in the heavy oil storage tank 16A and the light oil storage tank 16B through the light oil transfer pipe 24B. In addition, the heavy oil component is returned as a solvent to the middle of the raw material supply pipe 19a as a hydrocarbon through the partially generated oil return pipe 25 as a hydrocarbon oil, and is mixed with the waste plastic in the treatment tank 13 as described above. Supplied to

Further, in the above-mentioned method for easily converting waste plastic to oil, a residue composed of solid matter such as carbon residue (metal in waste plastic, sand and carbon due to thermal decomposition) is generated at the bottom of the treatment tank 13. Therefore, in the residue discharging step 45, the on-off valve 33 is periodically opened to take out the residue, and the pyrolysis oil contained in the residue is separated by the solid-liquid separation tank 14 (for example, a centrifuge). At this time, since the carbon in the pyrolysis oil in the processing tank 13 is granular and dispersed in the pyrolysis oil, it can be quickly discharged from the processing tank 13 to the solid-liquid separation tank 14. The pyrolysis oil separated from the residue is returned to the raw material supply pipe 19a through the pyrolysis oil reflux pipe 41 as a solvent composed of hydrocarbon oil. On the other hand, the residue from which the pyrolysis oil has been almost completely removed is supplied to a gasifier 37 through a residue transfer pipe 36, where it is gasified and the generated cracked gas is recovered. Then, the thermal energy generated by the combustion of the cracked gas can heat the thermal cracking oil flowing through the thermal cracking oil heating furnace 40. In addition, the combustion waste of the residue discharged from the discharge port of the rotary kiln 37 is taken out and disposed of.

As described above, in the present embodiment, waste plastic is put into a single treatment tank 13 together with hydrocarbon oil as a solvent, and the waste plastic and hydrocarbon oil are heated in the treatment tank 13. Elute polyethylene, polypropylene and polystyrene in waste plastic into hydrocarbon oil, pyrolyze the eluted polyethylene, polypropylene and polystyrene together with hydrocarbon oil, take out as pyrolyzed oil vapor and condense to produce oil At the same time, the residue after pyrolysis is taken out of the treatment tank 13, the hydrocarbon oil contained in the residue is separated in the solid-liquid separation tank 14, and the separated hydrocarbon oil is charged into the treatment tank 13. And the residue after the hydrocarbon oil is separated is used in the system as a heat source.

As described above, the elution of polyethylene, polypropylene and polystyrene in waste plastic into hydrocarbon oil and thermal decomposition in a single treatment tank 13 reduce the amount of residues discharged out of the system. it can. Therefore,
The amount of hydrocarbon oil accompanying this residue can also be reduced, and the yield of the produced oil can be increased. Further, by separating the hydrocarbon oil from the residue using the solid-liquid separation tank 14 and using it as a solvent, the profit of the generated oil can be further increased.

The residue after the hydrocarbon oil is separated in the solid-liquid separation tank 14 is partially burned to gasify or gasify by dry distillation, and this gas is recovered and used in the system as the heat source. Therefore, the residue that has been conventionally landfilled or incinerated can be effectively used as a heat source in the system of waste plastic oil treatment equipment A, and overall energy saving in waste plastic oil treatment equipment A is achieved. be able to. Since the treatment of the residue can be incorporated into the system of the waste plastic oil treatment equipment A, the waste plastic oil treatment equipment A can be made more compact. Since chlorine contained in the waste plastic is also removed in the treatment tank 13, the amount of chlorine remaining in the residue discharged from the treatment tank 13 after pyrolysis is small, and even when this residue is incinerated and gasified. Equipment costs for gas processing equipment can be reduced.

As described above, the present invention has been described with reference to one embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and is described in the claims. It also includes other embodiments and modifications that can be considered within the scope of the matters described. For example, as the hydrocarbon oil, oil from outside the system can be used, and as the type, for example, product oil (paraffin hydrocarbon, olefin hydrocarbon, and aromatic hydrocarbon (including ethylbenzene and styrene monomer) ) Or hydrocarbon oil obtained by distilling it (eg, aromatic hydrocarbon oil (ethylbenzene-rich oil), light / light oil fraction, heavy oil fraction, etc.), or paraffinic hydrocarbon or olefinic oil Hydrocarbons and xylenes, toluene, and other aromatic hydrocarbon oils can be used as solvents for waste plastics.

[0024]

According to the simple method of converting waste plastic into oil according to claims 1 to 3, the waste plastic is put into a single treatment tank together with a hydrocarbon oil as a solvent, and the waste plastic and carbonized oil are treated in the treatment tank. Heat the hydrogen oil and elute polyethylene, polypropylene and polystyrene in the waste plastic into the hydrocarbon oil, pyrolyze the eluted polyethylene, polypropylene and polystyrene together with the hydrocarbon oil, take out as a pyrolysis oil vapor and condense As well as producing the produced oil, the residue after pyrolysis is taken out of the treatment tank, the hydrocarbon oil contained in the residue is separated, and the separated hydrocarbon oil is used as a solvent to be charged into the treatment tank. The residue after the separation of the hydrocarbon oil is used as a heat source in the system.

As described above, by eluting polyethylene, polypropylene and polystyrene in waste plastics into hydrocarbons and pyrolyzing them in a single treatment tank,
The amount of residue discharged outside the system can be reduced. Therefore, the amount of the hydrocarbon oil accompanying the residue can be reduced, and the yield of the produced oil can be increased. Further, by separating the hydrocarbon oil from the residue and using it as a solvent, the profit of the produced oil can be further increased. Since the residue after the hydrocarbon oil is separated is used in the system as a heat source, the residue that has been conventionally landfilled or incinerated is effectively used as a heat source in the system of waste plastic oil treatment equipment. As a result, it is possible to achieve overall energy saving in the waste plastic oil treatment equipment.

In particular, in the method for easily converting waste plastic into oil according to the second aspect, the residue after the hydrocarbon oil is separated is partially burned to gasify or gasify by dry distillation, and this gas is recovered. As the heat source is used in the system, the heat efficiency can be increased, and it can be more effectively used as a heat source in the system of the waste plastic oil treatment equipment, and the overall energy saving in the waste plastic oil treatment equipment can be improved. Can be further promoted. According to the simplified method of converting waste plastic into oil according to the third aspect, chlorine contained in waste plastic is also removed in the treatment tank, so that chlorine remaining in the residue discharged from the treatment tank after thermal decomposition is removed. The amount is small, and even if this residue is incinerated or gasified, the equipment cost of the gas treatment equipment can be reduced.

[Brief description of the drawings]

FIG. 1 is a conceptual structural explanatory view of a main part of a waste plastic oil treatment apparatus to which a simple method of treating waste plastic according to an embodiment of the present invention is applied.

FIG. 2 is an explanatory view of a process in a processing tank.

FIG. 3 is a conceptual configuration explanatory view of an oil treatment section of a conventional waste plastic oil treatment apparatus.

[Explanation of symbols]

A Waste plastic oil treatment equipment 10 Pretreatment equipment 11 Thermal decomposition oil treatment equipment 12 Screw conveyor 13 Processing tank 14 Solid-liquid separation tank 15 Distillation tower 16A Heavy oil storage tank 16B Light oil storage tank 17 Stirrer 18 Rotary motor 19 Raw material input port 19a Raw material supply pipe 20 Pyrolysis oil vapor outlet 21 Hydrogen chloride gas outlet 22 Water vapor outlet 23 Vapor transfer pipe 24A Heavy oil transfer pipe 24B Light oil transfer pipe 25 Partial generated oil return pipe 26 Hydrogen chloride gas transfer pipe 27 Medium Sum treatment tank 28 Steam extraction pipe 29 On-off valve 30 On-off valve 31 On-off valve 32 Residue extraction pipe 33 On-off valve 34 Residue extraction port 35 Separated oil extraction port 36 Residue transfer pipe 37 Gasifier 38 Decomposed gas extraction pipe 40 Pyrolysis oil heating Furnace 41 Pyrolysis oil reflux pipe 42 Dehydration / drying process 43 Dechlorination process 44 Pyrolysis /
Oiling process 45 Residue discharging process

Claims (3)

[Claims] 1. A waste plastic is charged into a single treatment tank together with a hydrocarbon oil as a solvent, and the waste plastic and the hydrocarbon oil are heated in the treatment tank to produce polyethylene, Polypropylene and polystyrene are eluted in the hydrocarbon oil, the eluted polyethylene, polypropylene and polystyrene are pyrolyzed together with the hydrocarbon oil, and the resulting oil is produced by taking out and condensing as a pyrolyzed oil vapor, The residue after the thermal decomposition is taken out of the treatment tank, the hydrocarbon oil contained in the residue is separated, and the separated hydrocarbon oil is used as a solvent to be put into the treatment tank together with the waste plastic, A waste plastic, wherein the residue after the hydrocarbon oil is separated is used as a heat source in the system. A simple oiling treatment method for sticks. 2. The method according to claim 1, wherein the residue after the hydrocarbon oil is separated is partially burned to gasify or gasify by dry distillation.
2. The method according to claim 1, wherein the gas is collected and used as the heat source in the system. 3. The method for easily converting waste plastic to oil according to claim 1, wherein chlorine contained in the waste plastic is also removed in the single treatment tank.