JP2000087046A - Plastic thermal treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic thermal treatment apparatus which enables a solid fuel component to be stably recovered while preventing the blocking due to the solid fuel component from occurring in an org. substance recovery apparatus. SOLUTION: In this plastic thermal treatment apparatus, a plastic contg. a vinyl chloride resin is sent from a hopper 11 to screw feeders 12, 13 to be subjected to dehydrochlorination decomposition. The plastic is then thermally decomposed with a thermally melting vessel 14, and the resultant decomposition gas is sent to an org. substance recovery apparatus 16, where a solid component for fuel and an oil component for fuel are recovered. A part of the oil component is sent through returm lines 18a, 18b to the flow-in port 16a and the flow- out port 16b of the org. substance recovery apparatus 16 to agitate these sections and to keep the flowability in these sections. Thus, the blocking due to a solid component in the org. substance recovery apparatus can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic heat treatment apparatus capable of heating a plastic containing a vinyl chloride resin to decompose it by hydrogen chloride and melting it by heating to recover a fuel containing oil and solid components from the plastic. .

[0002]

2. Description of the Related Art From social problems such as the shortage of landfill sites and the establishment of the recycling law,
(Refuse Derived Fuel: solid fuel) fueling technology is attracting attention.

[0003] When a plastic contains a vinyl chloride resin, it is necessary to decompose with hydrogen chloride when regenerating the fuel by converting it into oil or RDF. In particular, when a soft vinyl chloride resin containing a large amount of plasticizer is contained, the plasticizer is evaporated and thermally decomposed during the dehydrochlorination, and phthalic anhydride, which is a decomposition product of the plasticizer, precipitates in the cooling pipe. Therefore, there is a problem that a blockage trouble is easily caused.

[0004]

In order to solve this problem, the present inventors introduced a plasticizer evaporation / decomposition gas into a temperature-controlled recovery tank in Japanese Patent Application No. 9-19195.
An attempt was made to condense / coagulate and recover this gas. However, it was found that there was a problem in stably operating the subsequent hydrochloric acid absorption tower.

[0005] The present invention has been made in view of the above-mentioned point, and stably removes by-products such as hydrochloric acid and phthalic acids from plastics containing a vinyl chloride resin without causing blockage in the system. An object of the present invention is to provide a plastic heat treatment apparatus that can be recovered.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a dehydrochlorination apparatus which heats and melts a plastic containing a vinyl chloride resin and decomposes the vinyl chloride resin into hydrogen chloride to produce hydrogen chloride gas. It has a heating and melting device that heats and melts plastic that has passed through the hydrogen device to generate a decomposition gas, and an inlet and an outlet.The decomposition gas generated by the heating and melting device is introduced from the inlet, and the decomposition gas is cooled. An organic matter recovery device that collects the fuel oil and the fuel solids and discharges the fuel oil from the outlet, and at least downstream of the outlet of the organic material recovery device, at least the fuel oil for the inlet or the outlet of the organic material recovery device. A plastic heat treatment device characterized by a return line for returning to the plastic, and decomposing the vinyl chloride resin with hydrogen chloride by heating and melting the plastic containing vinyl chloride resin A dehydrochlorination device that generates hydrogen chloride gas by performing the process, and a hydrogen chloride gas that has been passed through the dehydrochlorination device is introduced, and a hydrochloric acid absorption device that generates hydrochloric acid by mixing the hydrogen chloride gas and the absorbed water is provided. This hydrochloric acid absorption device is a plastic heat treatment device characterized by having an absorption water introduction port for introducing absorption water and an alcohol aqueous solution introduction section for introducing an alcohol aqueous solution.

According to the present invention, a plastic containing vinyl chloride resin is dehydrochlorinated in a dehydrochlorination apparatus to generate hydrogen chloride gas, and then the plastic is heated and melted in a heating and melting apparatus to generate a decomposition gas. I do. The cracked gas is led to the organic matter recovery device, where the fuel oil and the fuel solids are recovered in the organic matter recovery device. Among them, the fuel oil is returned to at least one of the inlet and the outlet of the organic matter recovery device by the return line, thereby preventing clogging of the fuel solid at the inlet and the outlet.

[0008] The hydrogen chloride gas generated in the dehydrochlorination apparatus is guided to a hydrochloric acid absorbing apparatus and mixed with the absorbed water to generate hydrochloric acid. The aqueous hydrochloric acid solution is introduced into the hydrochloric acid absorption device from the alcohol aqueous solution introduction section, and the organic solid content is washed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing one embodiment of a plastic heat treatment apparatus according to the present invention.

As shown in FIG. 1, a plastic heat treatment apparatus includes a hopper 11 having a cyclone 11a, and a hopper 1 having a cyclone 11a.
1 is provided with a first screw feeder 12 and a second screw feeder 13 which are sequentially connected.

In the hopper 11, a cyclone 11 is provided.
The plastic containing the vinyl chloride resin that has passed through a is supplied, and the plastic is heated by the first screw feeder 12 and the second screw feeder 13 to be decomposed with hydrogen chloride, thereby generating hydrogen chloride gas.

The plastic that has passed through the first screw feeder 12 and the second screw feeder 13 is then sent to a heating and melting device 14 where it is heated and melted, and a decomposition gas is generated from the molten plastic.

The heating and melting device 14 is connected to a decomposition tank (not shown) via a transfer pump 15 for discharging the molten plastic.

On the other hand, the hydrogen chloride gas generated in the first screw feeder 12 and the second screw feeder 13 and the decomposed gas generated in the heating and melting device 14 pass through the gas introduction line 25 and the organic matter recovery device 1
6, the decomposition gas is cooled in the organic matter recovery device 16, and the fuel oil and the fuel solid are recovered. The organic matter recovery device 16 has an inlet 16a and an outlet 16b.
And the gas introduction line 25 is connected to the inflow port 16 a of the organic matter recovery device 16.

The outlet 16b of the organic matter recovery device 16 is connected to a centrifuge 19 via a connection line 23 having a pump 23a. In this centrifuge 19,
The fuel oil content and the fuel solid content from the organic matter recovery device 16 are separated, and the fuel solid content is sent to the solid content recovery tank 22 via the discharge conveyor 21. On the other hand, the fuel oil from the centrifuge 19 is supplied to the oil recovery tank 20 and the discharge line 2.
Through 4, it is sent to a separation tank or a generated oil recovery tank (not shown).

A first return line 18 a for returning the solid content for fuel and the oil content for fuel to the outlet 16 b is connected to a connection line 23 connected to the organic matter recovery device 16, and is connected to the oil recovery tank 20. The discharge line 24 is connected to a second return line 18b that returns the fuel oil to the inlet 16a.

On the other hand, a hydrochloric acid absorption device 26 for introducing hydrogen chloride gas in the organic material recovery device 16 to generate hydrochloric acid is connected to the organic material recovery device 16 via a gas introduction line 30. The hydrochloric acid absorber 26 has a cooling water inlet 26a and a cooling water outlet 26b.
6 is provided with an absorption water inlet 27 into which absorption water for mixing with hydrogen chloride gas to generate hydrochloric acid is introduced. Further, an alcohol aqueous solution charging section 28 for charging an alcohol aqueous solution into the hydrochloric acid absorbing device 26 is connected to the absorption water inlet 27.

In the hydrochloric acid absorption device 26, the generated hydrochloric acid is sent to a hydrochloric acid recovery tank (not shown), and the exhaust gas from the hydrochloric acid absorption device 26 is sent to a neutralization tank.

Next, the operation of the present embodiment having the above configuration will be described. For example, a mixed plastic of 50 parts by weight of polyethylene and 50 parts by weight of a soft polyvinyl chloride resin (including 17.5 parts by weight of DOP as a plasticizer) is continuously fed into the first screw feeder 12 from the hopper 11 through the cyclone 11a. Is done. The mixed plastic is heated to 300 ° C. by the screw feeder 1 and to 350 ° C. by the screw feeder 2 and thus dehydrochlorinated.

The dehydrochlorination in the first screw feeder 12 and the second screw feeder 13 is performed as follows. That is, if the soft vinyl chloride resin is heated without supplying oxygen, dehydrochlorination of the vinyl chloride resin occurs at 200 to 350 ° C. In this decomposition, elimination of the side chain of the vinyl chloride resin occurs preferentially, and hydrogen chloride gas is generated. (C ₂ H ₃ CL) _n → (C ₂ H ₂ ) _n + nHCL ↑: dehydrochlorination decomposition reaction Simultaneously with the dehydrochlorination decomposition reaction, the plasticizer is also decomposed or evaporated.

During this time, the waste gas generated in the first screw feeder 12 is sent to a waste gas processing step. The mixed plastic that has passed through the second screw feeder 13 is heated and melted in a heating and melting device 14 while maintaining the temperature at about 350 ° C. to generate a decomposition gas. At this time, dehydrochlorination decomposition of the vinyl chloride resin further proceeds at the same time. The molten plastic from the heating and melting device 14 is sent to a decomposition tank via a transfer pump 15.

The thermal decomposition in the heating and melting device 14 is performed as follows. That is, plasticizers often used for vinyl chloride resins are dioctyl phthalate (DOP), dibutyl phthalate (DBP), and dioctyl adipate (DO).
A) and both are divalent carboxylic acid esters,
It is liquid at room temperature.

For example, the most frequently used dioctyl phthalate (more precisely, bis [2-ethylhexyl] phthalate) is obtained by thermal decomposition of phthalic anhydride as an acid anhydride and 2-ethylhexanol as an alcohol component as follows. And olefin components such as 2-ethyl-1-hexene as other components. It does not thermally decompose and the rate of evaporation is not negligible. _{C 6 H 4 [COO-CH} 2 -CH (C 2 H 5) -C 4 H 9] 2: DOP ( _{liquid) → CH 2 OH-CH (} C 2 H 5) -C 4 H 9: alcohol (liquid + C ₆ H ₄ (CO) ₂ ＯO: acid anhydride (solid) + CH ₂ ＣC (C ₂ H ₅ ) -C ₄ H ₉ : other main components (liquid) where the properties in parentheses are at room temperature. It is.

The basic behavior of decomposition is the same for plasticizers other than dioctyl phthalate, for example, diheptyl phthalate (DHP). Phthalic anhydride is used as an acid anhydride, heptanol is used as an alcohol component, and other components are used. Heptene and the like are produced, and evaporation occurs.

These plasticizer evaporation / pyrolysis products are liquid or solid at room temperature and can be recovered in the organic matter recovery unit 16 as described later.

The hydrogen chloride gas generated by dehydrochlorination and decomposition in the first screw feeder 12 and the second screw feeder 13 and the plasticizer evaporation / decomposition gas from the heating and melting device 14 are kept at a temperature of, for example, 150 to 300 ° C. The liquid is guided to the organic matter recovery device 16 via the gas introduction line 25, and is cooled by cooling water in a cooling jacket provided on the outer periphery of the organic matter recovery device 16.

In this manner, the cracked gas from the heating and melting device 14 is condensed / coagulated to produce a fuel oil component and a fuel solid component.

The fuel oil and fuel solids collected by the organic matter recovery unit 16 are continuously extracted from the bottom of the organic matter recovery unit 16 via a pump 23a, and are separated into solid and liquid by a centrifugal separator 19. . The fuel solids from the centrifugal separator 19 are collected in the solids recovery tank 22 via the discharge conveyor 21, and the fuel oils are collected in the oil recovery tanks.

During this time, in order to prevent the solids from settling in the organic matter recovery unit 16, a part of the fuel oil and the fuel solids extracted from the bottom of the organic matter recovery unit 16 is recovered again by the return line 18a. Return to the outlet 16b provided at the bottom of the device 16. Thus, the inside of the organic matter recovery device 16 can be maintained in a fluid state. Similarly, a part of the fuel oil (mainly 2-ethylhexanol) from the oil recovery tank 20 is returned to the inlet 16a of the organic matter recovery device 16 through the return line 18b, so that the decomposed gas from the gas introduction line 25 is returned. And the fuel oil can be mixed.

As described above, by returning the solid content for fuel and the oil content for fuel to the outlet 16b provided at the bottom of the organic matter recovery device 16 through the return line 18a, the bottom of the organic material recovery device 16 is agitated, and the solid content for fuel is returned. It is possible to prevent the components from settling at the bottom of the organic matter recovery device 16. Further, by returning the fuel oil to the inflow port 16a of the organic matter recovery device 16 through the return line 18b, it is possible to prevent the deposition and accumulation of the fuel solids at the inflow port 16a. Further, it is possible to prevent a blockage trouble at the outlet 16b.

On the other hand, a gas mainly composed of hydrogen chloride gas (boiling point = −85 ° C.) which is not condensed in the organic substance recovery unit 16 passes through the gas introduction line 30 through the baffle plate 16 c of the organic substance recovery unit 16 and the hydrochloric acid absorption unit 26. It is led to.
In the hydrochloric acid absorption device 26, the hydrogen chloride gas is mixed with the absorption water flowing from the absorption water inlet 27 to form hydrochloric acid, and is recovered in a hydrochloric acid recovery tank (not shown).

The heat generated in the hydrochloric acid absorber 26 is
Cooled by cooling water flowing from the cooling water inlet 26a,
The cooling water is discharged from a cooling water outlet 26b.

The exhaust gas from the hydrochloric acid absorption device 26 is sent to a neutralization tank, detoxified, and then released to the atmosphere.

As described above, in the hydrochloric acid absorbing device 26, the hydrogen chloride gas is absorbed by the absorbed water and recovered as hydrochloric acid. In this case, in the case where the organic matter derived from the plasticizer is clogged due to precipitation and deposition in the hydrochloric acid absorbing device 26, an alcohol aqueous solution such as a methanol aqueous solution is allowed to flow from the alcohol aqueous solution charging section 28 for a certain time instead of the absorbed water. To wash off organic matter. At this time, a part of the acid anhydride such as phthalic anhydride is liquefied by causing an esterification reaction with the aqueous alcohol solution.

The hydrochloric acid in the hydrochloric acid recovery tank may be supplied to the organic matter recovery device 16 as needed. Also the first
Screw feeder 12, second screw feeder 1
3, and an N2 purge gas can be sent into the heating and melting tank 14.

[0036]

Embodiment 1 Next, a specific embodiment of the present invention will be described. Using the plastic heat treatment apparatus described in the above embodiment of the present invention, plastic heat treatment was performed under the same conditions as in the above embodiment, except that the aqueous alcohol solution was not charged into the hydrochloric acid absorption device 26. .

The results of the recovery are shown in the table below. Recycled materials Hydrochloric acid Oil content Solid content Exhaust gas weight part 70 52 9 21

In the above table, the concentration of the recovered hydrochloric acid was 35%.
The recycled material is the molten plastic obtained in the heating and melting tank 14.

In this embodiment, stable continuous operation for about one month was possible.

[0040] Except that no reflux Comparative Example 1 recovered oil to the inlet 16a of the organic matter recovery device 16 was carried out the same tests as in Example 1. As a result, phthalic anhydride was precipitated at the inlet 16a and the outlet 16b of the organic matter recovery device 16, and the tube was clogged, making it difficult to continue the test.

Example 2 The same test as in Example 1 was performed. However, once every two weeks
For about one hour, a 20% aqueous methanol solution was passed through the hydrochloric acid absorption device 26 instead of the absorption water. As a result, the material balance was the same as in Example 1, and a long-term continuous operation of one month or more was possible.

[0042]

As described above, according to the present invention, clogging with fuel solids can be prevented beforehand at the inlet or outlet of the organic matter recovery device or the hydrochloric acid absorbing device, and hydrochloric acid and fuel solids can be prevented. It can be recovered stably.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a plastic heat treatment apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Hopper 12 1st screw feeder 13 2nd screw feeder 14 Heating / melting tank 16 Organic substance recovery apparatus 16a Inflow port 16b Outflow port 18a, 18b Return line 26 Hydrochloric acid absorption apparatus 27 Absorption water inlet 28 Alcohol aqueous solution introduction part

Claims (2)

[Claims] 1. A dehydrochlorination device for heating and melting a plastic containing a vinyl chloride resin to dehydrochlorinate the vinyl chloride resin to generate hydrogen chloride gas, and heating and melting the plastic that has passed through the dehydrochlorination device. A heating and melting device that generates cracked gas by heating, and has an inlet and an outlet. The cracked gas generated by the heating and melting device is introduced from the inlet, and the cracked gas is cooled to reduce fuel oil and fuel solids. And a return line for returning at least the fuel oil to the inlet or the outlet of the organic matter recovery device on the downstream side of the outlet of the organic material recovery device. A plastic heat treatment apparatus. 2. A dehydrochlorination apparatus which heats and melts a plastic containing a vinyl chloride resin and decomposes the vinyl chloride resin into hydrogen chloride to produce hydrogen chloride gas. And a hydrochloric acid absorbing device for mixing the hydrogen chloride gas and the absorbing water to generate hydrochloric acid, and the hydrochloric acid absorbing device includes an absorbing water inlet for introducing the absorbing water;
A plastic heat treatment apparatus comprising: an alcohol aqueous solution charging section for charging an alcohol aqueous solution.