JPH0610279B2 - How to dispose of plastic waste - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for treating plastic waste, and in particular,
By pyrolysis and separation treatment methods, plastic waste can be converted into petroleum fuel products such as light oil and diesel oil and recycled substances such as carbon black, coke, tar, etc. It relates to the disposal method of plastic waste products that do not exist.

<Prior Art> Since 1970, plastic products have been emphasized in place of traditional wood and metal products.
There is a problem that plastic products cannot be decomposed by microorganisms existing in the natural world, and the increase of waste generated by the large amount of use of plastic has reached a stage where it cannot be ignored.

The conventional treatment of plastic waste products is roughly classified into a combustion method and a selective recovery method. That is, the combustion method directly
In contrast to the method of incinerating plastic waste products, the selective recovery method is a method of selecting plastic waste products and recycling those that can be used. However, the former requires a completely consumptive means and incidental equipment to prevent environmental pollution due to combustion, and the latter requires various fillers or foreign substances to be mixed in the plastic. Therefore, the processing in the selection process is difficult, and the quality of the recycled plastic is poor, so that it has not reached the stage of practical application.

<Problems to be Solved by the Invention> In light of the above points, the present inventor has completed the present invention as a result of intensive research. That is, the main object of the present invention is to dispose of plastic waste products as a light oil, by a pyrolysis and separation treatment method.
It is an object of the present invention to provide a method for treating plastic waste products which can be converted into and recovered from liquid substances such as diesel oil and solid substances such as carbon black, coke and tar.

Another object of the present invention is to provide a method for treating plastic waste in a closed system and treating the plastic waste without polluting the environment.

<Means for Solving the Problem> In order to achieve the above object, the present invention provides a method of thermally decomposing a plastic waste product and then decomposing the same, in which (a) a petroleum organic solvent is added to the plastic waste product and gradually The first step of thermal decomposition is carried out by heating at a temperature of 500 ° C. or lower and a pressure of 3 kg / cm ² or lower while melting while increasing the temperature to generate a gas, and (b) the generated gas mixture is continuously added. Is introduced into the reaction tank for further second stage thermal decomposition, (c) the gas mixture produced in the second stage is stabilized by cooling, and (d) the stabilized gas mixture is cooled to room temperature and then separated. By operation, it is separated into a gas mixture and a liquid mixture, and (e) the separated and acquired liquid mixture is obtained as a fraction of light oil, diesel oil, etc. by a distillation operation, and
The gas mixture is used as a heating fuel in the step (a) and / or the step (b).

In the treatment method of the present invention, the petroleum solvent that dissolves the plastic waste in step (a) can be any petroleum liquid fuel such as light oil, heavy oil, diesel oil, etc. It is particularly preferable because it is the highest and can dissolve the plastic easily.

<Examples> Hereinafter, one embodiment of processing polyethylene waste products using heavy oil in one example of the method of the present invention will be described based on the flow sheet of FIG. However, the scope of the present invention is not limited to the description of the examples below.

As shown in FIG. 1, about 0.1 parts by weight of heavy oil relative to polyethylene waste and 1 part by weight of polyethylene are introduced into the dissolution gasification tank R ₁ by the supply device E ₁ . The dissolution gasifier R ₁ is a heating device of an indirect heating type, and the polyethylene waste and the heavy oil seal the device R ₁ and the first stage heating is performed by a burner from outside while stirring and melting. Regarding the heating temperature of the first stage, it is initially 85 ° C to 13 ° C.
At 0 ° C, almost all polyethylene waste products in this temperature range are dissolved. Then, when the temperature is gradually raised, gas generation starts at around 200 ° C.
At this time, the pressure in the kettle R ₁ rises suddenly, and therefore it is necessary to maintain the pressure in the kettle R ₁ so that it is always 3 kg / cm ² or less in all heating processes. Also, the temperature is 340-3
When reaching 80 ° C, the waste polyethylene becomes a viscous liquid, and the gas generation rate becomes the highest at about 400 ° C to 450 ° C. When the temperature in the kettle R ₁ reaches up to 500 ° C., most of the gasification component of the polyethylene waste product solution is gasified, and a part of the gas is broken into short pieces due to the decomposition of molecular chains due to cracking. The generated gas in the dissolution gasification tank R ₁ is immediately introduced into the reaction tank R ₂ via the conduit 21.

Although the dissolution gasification treatment of the polyethylene waste product of the present example is performed by the batch method, a large number of polyethylene waste products are more efficiently sequentially arranged in parallel with a plurality of dissolution gasification kettles by the distribution method,
It can also be processed economically.

In the waste polyethylene product, sludge remains in the kettle R ₁ due to the above-mentioned dissolution gasification process, but this sludge is light-weight porous and black spongy. This spongy material can be used as an absorbent material for industry, and because of its low thermal conductivity,
Crush with a crusher to a powder of about 2 mmφ and clay,
High-grade refractory bricks such as carbon bricks can also be obtained by kneading with a refractory material such as asbestos and performing a molding and firing treatment. Further, coke, tar, etc. can be obtained by appropriately controlling the temperature of the dissolution gasification tank R ₁ according to actual demand.

In the anti-agricultural tank R ₂ , the second-stage thermal decomposition is performed, and at a higher temperature of 600 ° C. and a pressure of ² kg / cm ² , gas molecules having a long molecular chain that have not yet been thermally decomposed in the dissolution gasifier R ₁ are further added. Disconnect. Since the thermal decomposition of the gas molecules in the dissolution gasifier R ₁ is not complete, the already cleaved molecular chains of the gas molecules are likely to become molecules with a long molecular chain again due to reforming. ₂ , as shown in FIG. ₂ , plates 41 are provided in the reaction tank R ₂ main body at substantially equal intervals, and a plurality of small holes 42 are opened so as to alternately face the ends of the plates 41 on each floor. It is composed.
With such a configuration, the gas introduced from the dissolved gas tank R ₁ is heated while sequentially passing through the small holes 42 of the plate 41 of each layer from the bottom layer, so that the reforming of gas molecules is prevented by the reverse reaction. It can also promote the degradation (cracking) of uncleaved molecules.

The gas obtained in the reaction tank R ₂ is continuously introduced into the stabilizing tank R ₃ via the conduit 22. Since the temperature in the stabilizing tank R ₃ is maintained around 400 ° C., the gas thermally decomposed in the reaction tank R ₂ is instantaneously stabilized because it does not lead to a long molecular chain, and the reverse reaction is suppressed.

The temperature of the stabilizing tank R ₃ is set to 4 by using the cooling heavy oil fed from the supply device E ₁ by the conduit 23 via the pump P _1.
The heavy oil whose temperature has been lowered to 00 ° C and whose temperature has risen due to heat exchange is returned to the supply device E ₁ via the conduit 24, and is configured to preheat polyethylene waste and heavy oil so that the waste heat can be sufficiently reused. it can.

The gas completely stabilized in the stabilizing tank R ₃ is supplied to the conduit 2
Is introduced into the first condenser F ₁ (condenser) via 5
It is cooled to 00 ° C. Thus, the gas is almost completely stabilized and partly liquefied. The obtained product is further introduced into the second condenser F ₂ via the conduit 26,
It is cooled down to around 35 ° C.

The mixture of gas and liquid obtained in the second condenser F ₂ is supplied to the separation device S ₁ via the conduit 27. In the separator S ₁ , the mixture is separated into a gas mixture and a liquid mixture. The liquid mixture is supplied to the distillation apparatus T ₁ via a conduit 28, while the gas mixture is stripped by a vacuum pump P ₂ via a conduit 29 into strippers S ₂ , respectively.
The dried gas and the condensed liquid mixture are separated from the gas mixture by being supplied to S ₃ and S ₄ . The dried gas is fed into and stored in the gas storage tank S ₅ via the conduit 31, and the condensed liquid mixture is passed through the conduit 30 to the separation device S 5.
Return to ₁ . Further, the gas in the gas storage tank S ₅ is fed into the dissolved gas tank R ₁ and / or the reaction tank R ₂ via the conduit 32 and is reused as fuel.

Since incomplete combustion occurs in the combustion of the gas in this embodiment, the smoke generated by the combustion is introduced into the carbon black collecting device K ₁ through the conduit 32 to generate carbon black.

The substantially gas-free liquid mixture in the distillation apparatus T ₁ is separated into light oil and diesel oil. As shown in FIG. ₁ , the distillate from the distillation apparatus T ₁ , that is, the one obtained by condensing the vaporized fraction in the fractional distillation is passed through a conduit 33 to a condenser F ₃
After being introduced and condensed, they are introduced into storage tanks S ₆ and S ₇ via conduits 34 and 35, respectively. 2 in storage tank S ₆
Light oil distilled in a temperature range of 0 to 200 ° C. is stored in a storage tank S ₇
In, the diesel oil distilled in the temperature range of 200 to 450 ° C is stored. Further, the light oil and the diesel oil from the storage tanks S ₆ and S ₇ are respectively washed with the cleaning tanks S ₈ and S ₉ and the decolorization tank S.
₁₀ and S ₁₁ , and is washed with water and decolorized.

In the above example, when the input amount is 1000 kg of polyethylene waste and 100 kg of heavy oil for dissolution, the output is 250 kg of light oil, 400 kg of diesel oil, 50 kg of oils having a boiling point higher than diesel oil, 150 kg of combustion gas, residual solids. A result of 150 kg min was obtained.

In this way, by performing the thermal decomposition by the two-stage treatment, as the first step, the petroleum solvent is heated as a heating medium, causing thermal decomposition, so that solidification due to, for example, charring is delayed, and thermal efficiency is improved, Further, in the second step, the gasification component is introduced as a gas into the reaction vessel through a pipe, and the gasification component is passed through the bypass passage as described in the example to obtain a temperature of 600 ° C.
Since pyrolysis is carried out at a high temperature such as, the effect of promoting cracking and not causing reforming to re-proliferate a chain of a molecule that has already been cut short was obtained.

<Effects of the Present Invention> As described above with reference to the embodiments shown in the drawings, according to the processing method of the present invention, the two-stage heat treatment is performed to decompose the plastic waste, so that the plastic waste is Light oil, diesel oil, continuously and without polluting the environment,
It can be recovered by converting it to carbon black, coke, tar, etc. As a result, plastic waste, which has been conventionally regarded as a cause of environmental pollution and poses a major processing problem, can be easily and effectively recovered and recovered by treating it without causing pollution. it can.

[Brief description of drawings]

FIG. 1 is a schematic flow sheet of one embodiment for treating polyethylene waste with heavy oil in carrying out the method of the present invention,
FIG. 2 is a side sectional view of a reaction tank used in the method of the present invention. E ₁ ... Supply device R ₁ ... Dissolution gasification kettle R ₂ ... Reaction tank R ₃ ... Stabilization tank F ₁ , F ₂ , F ₃ ... Condenser S ₁ ... Separation device P ₁ , P ₂ ... Pump T ₁ ... Distillation device _{S 2, S 3, S 4} ... stripper _{S 5, S 6, S 7} ... storage tank K 1 _... collecting device S _8, S 9 _... cleaning tank S _10, S _{11 ...} bleaching tank 21, 22, 23, 24, 25, 26, 27, 28, 2
9, 30, 31, 32, 33, 34, 35 ... Conduit 41 ... Plate 42 ... Small hole

Claims (5)

[Claims] 1. A method of thermally decomposing a plastic waste product and then decomposing the same, wherein (a) heavy oil is added to the plastic waste product, and the temperature is 500 ° C. or less and the pressure is 3 kg while melting while gradually increasing the temperature.
The first stage of thermal decomposition is carried out by heating at a temperature of less than 1 / cm ² to generate gas, and (b) the generated gas mixture is continuously introduced into the reaction tank to carry out the second stage of thermal decomposition. (C) The gas mixture produced in the second step is stabilized by cooling, (d) the stabilized gas mixture is cooled to room temperature, and then separated by a separation operation into a gas mixture and a liquid mixture, (e) The separated liquid mixture is obtained as a fraction of light oil, diesel oil, etc. by distillation operation,
A method for treating plastic waste, comprising using the gas mixture as a heating fuel in the step (a) and / or the step (b). 2. In the step (a), the plastic waste is decomposed by the first stage thermal decomposition, and after that, coke, tar, refractory raw material, etc. are obtained from the residual solid content. The method for treating plastic waste according to claim 1. 3. In the step (b), the second-stage pyrolysis is carried out at a temperature of 500 to 600 ° C. and a pressure of 2 kg / cm ² . How to dispose of plastic waste. 4. In the step (b), the reaction tank is provided with plates in the reaction tank body at substantially equal intervals, and a plurality of small holes are alternately formed in the vicinity of the end of the plate on each floor. The method for treating a plastic waste product according to claim 1, wherein the gas molecules can be cut into layers one by one. 5. In the step (e), the gas mixture is
The method for treating plastic waste according to claim 1, wherein carbon black is obtained by incomplete combustion by circulating the carbon black in step (a) and / or step (b).