JP4322365B2 - Oil waste treatment method and apparatus for plastic waste - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil processing method and apparatus for converting various plastic wastes into oil by thermal decomposition and collecting them for reuse.
[0002]
[Prior art]
Conventionally, as a method for oily treatment of plastic waste, for example, gaseous pyrolysis products generated by pyrolysis in a pyrolysis tank are separated into crude heavy oil components and light oil components using a pyrolysis steam heat exchanger. The light oil component is condensed by a light oil condensing heat exchanger, the light oil is taken out, a part of the light oil is vaporized and supplied to the pyrolysis tank, and a method of proceeding the thermal decomposition is proposed. (Japanese Patent Laid-Open No. 10-195542). The vaporized light oil acts as a heat source for thermal decomposition in the thermal decomposition tank, and at the same time, prevents molten plastic waste from coking and adhering to the tank wall and piping. In the pyrolysis tank, pre-melted plastic waste may be continuously added, or solid plastic waste may be added and thermally decomposed batchwise. Residue generated after completion is taken out from the bottom of the pyrolysis tank to the residue receiving tank.
[0003]
[Problems to be solved by the invention]
The method of separating the pyrolysis product into the crude heavy oil component and the light oil component by the conventional pyrolysis steam heat exchanger is a relatively rough separation, so the heavy oil component is added to the light oil. In order to vaporize this light oil for supply to the pyrolysis tank, it is not possible to completely vaporize unless it is high temperature, and it is necessary to prepare a high-temperature heat source for vaporization. Further, in the heating section of the vaporization, the pressure cannot be increased because the steam is not liquefied, and in order to prevent the pressure increase, the diameter of the pipe needs to be 60 mm to 80 mm when the light oil flow rate is 2000 kg / h, for example. There was a disadvantage that the price of the device was expensive. Heavy oil components tend to solidify due to a decrease in temperature, and if they are removed together with residues, the piping must be cleaned in a short period of time to clog the piping, which deteriorates the operating efficiency of the equipment. It is not preferable because it leads to high cost of oil treatment.
[0004]
An object of the present invention is to provide a method for oily treatment of plastic waste over a long period of time at low cost by preventing the generation of coke and an apparatus suitable for this.
[0005]
[Means for Solving the Problems]
In the present invention, in an oil conversion method in which molten plastic waste is pyrolyzed in a pyrolysis tank and the cracked oil is recovered from the gaseous pyrolysis product generated thereby, the pyrolysis product is ejected from the ejector. with the forcibly taken out from the pyrolysis chamber to supply to the atmospheric distillation column to give a light oil by cooling it is taken out only vapor generated in the normally distillation column, pumping a portion of the light oil In the middle of this, it was vaporized and introduced into the pyrolysis tank, so that it was used as a heating source for the plastic waste, thereby achieving the above object. The thermal decomposition tank may be a batch-type thermal decomposition tank, and plastic waste may be charged and melted therein. After the dehydrochlorination treatment of the melt, the thermal decomposition may be performed. Efficient operation can be performed by pumping the bottom oil produced in the atmospheric distillation tower to the ejector and using it as a drive liquid for the ejector. The steam from the atmospheric distillation tower is cooled by the light oil pumped to the pyrolysis tank, and then the light oil is vaporized by the bottom oil generated in the atmospheric distillation tower. Utilization is improved, and the tower bottom oil can be heated and then dechlorinated to obtain a hydrocarbon oil that is no different from commercial heavy oil.
[0006]
In the above method, an atmospheric distillation column is connected to a thermal decomposition tank for thermally decomposing plastic waste through an ejector for extracting a gaseous thermal decomposition product generated by the thermal decomposition, A light oil tank connected through a pipe for deriving the steam of the gas, a pump for pumping the light oil in the light oil tank, and a pipe connected to the pyrolysis tank provided with a heating means for vaporization, and the atmospheric distillation A pipe for leading the tower bottom oil accumulated in the tower can be appropriately implemented by an oil treatment apparatus connected to the ejector via a pump.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described with reference to the explanatory view of the batch type plastic waste oil treatment apparatus shown in FIG. 1. In FIG. 1, reference numeral 1 denotes a heat which contains solid plastic waste and is sealed. Decomposition tank 2 is a light oil tank for storing light oil generated by the plastic waste oil processing, and 3 is a heavy oil tank for storing the heavy oil generated by the oil processing. The pyrolysis tank 1 is provided with a jacket 4 through which a heating fluid circulates on the peripheral wall, and light oil prepared in advance in the light oil tank 2 is heated by the heat exchangers 14 and 23 in the jacket 4 and the tank. And heated in the heating furnace 5 and supplied from the pipe 6, the plastic waste introduced by the heat from the jacket 4 and the light oil supplied into the tank is melted, dehydrochlorinated, Thermally decomposes.
[0008]
The temperature of the light oil supplied from the pipe 6 to the jacket 4 is first heated to, for example, 200 ° C. or less by the heating furnace 5, and after the plastic waste in the tank is melted, the temperature is about 200 to 320 ° C. The chlorine gas generated with this melting is introduced to the dehydrochlorination tank 7 for dehydrochlorination treatment. This treatment removes about 90% of the chlorine contained in the plastic waste. Subsequently, for example, 470 ° C. light oil is supplied into the tank to thermally decompose the plastic waste that has been melted, and the gaseous pyrolysis product that is generated is forced and quickly discharged from the tank by the ejector 8. Draw out and supply to the atmospheric distillation column 9 via the pipe 10. Chlorine remaining without being desalted remains in the tank as hydrochloric acid, resulting in chlorination of hydrocarbons. Therefore, the time spent in the tank of the pyrolysis product is shortened by suction of the ejector 8, and the chlorination is reduced. It was hard to occur.
[0009]
The atmospheric distillation column 9 is a known one, and a heat medium whose temperature is adjusted to 350 ° C. by a heat medium boiler 11 circulates through the reboiler 12, and the pyrolysis product supplied thereto is gasified at about 170 ° C. The product is separated into a thermal decomposition product and a liquid thermal decomposition product. Only the thermal decomposition product in the gaseous state generated in the atmospheric distillation column 9 is taken out via a pipe 13 and finally is about about 30% by a heat exchanger 14 and a column top liquid cooler 15 provided in the middle of the pipe 13. It is cooled to 50 ° C., condensed as light oil, and stored in the light oil tank 2. Since the light oil thus obtained is separated by the atmospheric distillation column 9, it is a so-called light oil that can be completely vaporized at 300 ° C. even at a pressure of about 2 kg / cm 2 G. The stored light oil is pumped to the pipe 6 by the pump 16, vaporized by the heat exchangers 14, 23 provided in the middle thereof, the steam temperature is raised to 470 ° C. in the heating furnace 5, for example, and the jacket 4 and It is supplied into the tank as a heat source for the plasticization of plastic waste. This steam passes in a steam state into the tube 5a of the heating furnace 5 and is heated at that time. Therefore, the surface of the tube 5a is 500 ° C. without causing a phase change that gasifies from the liquid. There is almost no coke formation. In addition, since the pressure in the tube 5a can be set high, the diameter of the tube 5a is reduced to, for example, 40 mm when the flow rate of light oil is 2000 kg / h, compared to the case where heating is performed with normal-pressure steam. The price of the heating furnace 5 that is so expensive that it accounts for 20 to 30% of the total price of the oil generator can be greatly reduced.
[0010]
The pyrolysis product that accumulates in the liquid state at the bottom 9 a of the atmospheric distillation column 9 is a heavy oil component bottom liquid at about 273 ° C., and a part of the driving liquid for the ejector 8 is supplied by the pump 17. And the remainder is stored in the heavy oil tank 3 through a pipe 22 provided with the heating furnace 5, flasher 19, dechlorination reactor 20 and condenser 21. This bottom liquid is a hydrocarbon oil from which light oil has been almost completely removed by distillation, and a heavy oil that is not different from commercially available heavy oil can be obtained by complete desalting in the dechlorination reactor 20. .
[0011]
Residues generated in the pyrolysis tank 1 due to pyrolysis are discharged to a residue receiving tank 25 by a screw conveyor 24 provided at the bottom of the tank. As a heat source for the heating furnace 5, light oil in the light oil tank 2 and its vaporized gas were burned and used.
[0012]
In the above description, the batch type liquefaction treatment has been explained. However, the plastic waste charged into the pyrolysis tank is previously melted in a melting furnace or a dehydrochlorination tank provided separately from the pyrolysis tank. And dehydrochlorinated.
[0013]
【Example】
1500 kg of crushed plastic waste is put into the pyrolysis tank 1, and at the same time, the heating medium heater 11 is operated, the reboiler 9a of the atmospheric distillation tower 9 is heated, and the bottom liquid is heated to about 280 ° C. The pump 17 was pumped to the ejector 8. The open / close valve 26 was closed to set the operation state in which the ejector 8 did not perform the suction operation, and the column bottom oil was returned to the column bottom 9a. When the heat exchanger 23 is heated by circulation of the bottom oil, the light oil prepared in the light oil tank 2 is pumped by the pump 16 and vaporized by the heat exchanger 23 at 279 ° C. The temperature was raised to ° C. and supplied to the jacket 4, and plastic waste was melted at 200 ° C. The composition of the plastic waste is 50 wt% polyethylene, 15 wt% polypropylene, 25 wt% polystyrene, and 10 wt% polyvinyl chloride. The operating conditions of the heating furnace 5 were a pressure of 1.9 kg / cm @ 2 G, a light oil flow rate of 2000 kg / h, and the tube 5a of the heating furnace 5 was produced with a diameter of 40 mm . After the melting, the temperature is raised and the temperature in the pyrolysis tank 1 at 300 ° C. is maintained for 30 minutes. Chlorine gas generated at the initial stage of melting is sent to the dehydrochlorination tank 7 to perform dehydrochlorination treatment. 30 minutes after the completion, the temperature of the heating furnace 5 was raised, light oil vaporized at 410 ° C. was supplied into the tank, and the molten plastic waste was thermally decomposed. Thermal decomposition products of the thermal decomposition tank 1 is sent slight to a more distillation column 9 to the ejector 8 at the residence time in the vessel, the overhead oil lighter oil component vaporizes at about 170 ° C., the heat exchanger 14 and is condensed in overhead liquid cooler 15 is stored in the light oil tank 2, a heavy oil component liquid accumulates in the bottom 9a at 170 ° C., the ejector 8 by the pump 17, the heating furnace 5, the flasher 19, dechlorination It was stored as heavy oil in the heavy oil tank 3 through the reactor 20 and the condenser 21. The pyrolysis time was 6 hours, and the generated carbon residue was discharged into the residue receiving tank 25. The final component ratio of the pyrolysis product was 10 wt% gas, 30 wt% soft oil, and 2 wt% carbon. Light oil vapor passes through the tube 5a of the heating furnace 5 at a relatively high pressure, and even if the diameter is small, no coke adheres, and the manufacturing cost of the heating furnace 5 is 50% or more than that of the conventional 80 mm. I was able to produce it cheaply.
[0014]
【The invention's effect】
As described above, according to the present invention, the thermal decomposition product was forcibly taken out from the thermal decomposition tank by an ejector and supplied to the atmospheric distillation column, and only the vapor generated in the atmospheric distillation column was cooled. A portion of light oil was cut and introduced into the pyrolysis tank, and used as a heat source for plastic waste. Therefore, the vaporization can be performed at a relatively low temperature, eliminating the need for a high-temperature heat source. In the furnace, steam is heated, so there is no risk of liquefaction even if the pressure rises slightly, and coke generation can be prevented and oiling operation can be performed for a long time, so the processing cost is reduced and the furnace tube has a small diameter. Since the apparatus can be manufactured, the apparatus is also inexpensive, and the thermal decomposition product is drawn out by the ejector, so that the thermal decomposition rate can be increased by setting the inside of the thermal decomposition tank to normal pressure or negative pressure. And 7 The effect of the method of the present invention can be suitably carried out by.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the apparatus of the present invention.
1 pyrolysis tank, 2 light oil, 3 heavy oil, 4 jacket, 5 heating furnace, 8 ejector, 9 atmospheric distillation tower, 14/23 heat exchanger,

Claims (6)

In an oil treatment method in which molten plastic waste is pyrolyzed in a pyrolysis tank and the cracked oil is recovered from the gaseous pyrolysis product generated thereby, the pyrolysis product is removed using a driving liquid. By ejecting the pyrolysis product forcibly from the pyrolysis tank and supplying it to the atmospheric distillation tower with a sucking ejector , a light oil is obtained by taking out and cooling only the vapor generated in the atmospheric distillation tower, A part of the light oil is pumped and vaporized in the middle of the light oil and introduced into the pyrolysis tank to be used as a heating source for the plastic waste, and the bottom oil produced in the atmospheric distillation column is used as the ejector. A method for oily treatment of plastic waste, wherein the plastic waste is used as a drive fluid for the ejector .   The said pyrolysis tank is a batch-type pyrolysis tank, and plastic waste is poured into the tank and melted, and after the dehydrochlorination treatment of the melt, the pyrolysis is performed. The method for liquefying plastic waste according to claim 1. The steam from the atmospheric distillation column was cooled by light oil, which is pumped into the pyrolysis chamber, it claims thereafter characterized by vaporizing the said light quality oil in bottom oil produced in the normally distillation column Item 3. The method for oily treatment of plastic waste according to Item 1 or 2 . 4. The plastic waste oil conversion method according to claim 3, wherein the bottom oil produced in the atmospheric distillation tower is heated and then dechlorinated to obtain a hydrocarbon oil.   An atmospheric distillation column is connected to a thermal decomposition tank that thermally decomposes plastic waste through an ejector that draws out a gaseous thermal decomposition product generated by the thermal decomposition, and the vapor in the atmospheric distillation column is derived. A light oil tank connected via a pipe, a pump connected to the pyrolysis tank provided with a pump for pumping the light oil in the light oil tank and a heating means for vaporization, and a tower that is accumulated in the atmospheric distillation column A plastic waste oil processing apparatus, characterized in that a pipe for extracting bottom oil is connected to the ejector via a pump. Branch piping for deriving the bottoms oil, according to claim 5, characterized in that connected to the heavy oil tank for storing the heavy oil through the branch pipe heating means and dechlorination reactor Plastic waste oil processing equipment.

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