JP2000309781A - Apparatus for continuous conversion of plastic into oil by carbonization and heat decomposition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for continuously converting a plastic into an oil by carbonization and heat decomposition whereby the operation can be done with improved safety, and a heavy oil and a light oil can be separated at good efficiency. SOLUTION: This apparatus is provided with a first screw feeder 5 for the ordinary temperature compression of the plastic to be treated; a horizontal second screw feeder 21 for dissolution and dechlorination; an inclined third screw feeder 41 for low-temperature region heat decomposition; an inclined fourth screw feeder 61 for high-temperature region decomposition; first to third heaters 22, 45, and 65 which feed a recirculated heating inert gas to the second to fourth screw feeders and provided with volatile gas detectors 50, etc.; a condenser 81 through which the third and fourth screw feeders are connected to each other; a first gas/liquid separator 82; a second gas/liquid separator 83 connected to the bottom of the separator 82; and a third gas/liquid separator 85 connected to the top of the separator 83.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for continuous pyrolysis and cracking of plastics, particularly waste plastics.

[0002]

2. Description of the Related Art In recent years, the consumption of plastic products has been increasing steadily, and it has been desired to recycle waste plastics by thermal decomposition oil instead of incineration or landfill. Waste plastics to be treated (hereinafter referred to as “plastics to be treated”) can be roughly divided into six methods: a molten bath type, a two-stage type, a screw type, a pipe still type, a fluidized bed type, and a contact type. Is mentioned. Of these, the screw type has a relatively simple structure,
It is considered that the treatment efficiency is good because it can be continuously converted to oil by thermal decomposition. As a plastic continuous carbonization pyrolysis oil conversion device using this screw type, a horizontal one-stage system and a horizontal two-stage system have been proposed.

[0003]

In the above-mentioned screw type plastic dry distillation pyrolysis oilizer, the screw is directly heated with hot air or heated using microwaves. If cracks occur in the pipe, the leaked volatile gas will cause serious problems such as explosion and combustion. Also, when the plastic to be processed, which has been carried into the first screw feeder from the carry-in hopper, is compressed under heating, the plastic is rapidly melted by heat, causing air to flow into the system, causing a phenomenon called blowout. there were. Further, heavy oil and light oil obtained by converting plastic to oil have not been efficiently separated. The present invention solves the above-mentioned problems by using an inert gas as a heating medium and improving the safety during operation than before, and further using heavy oil and light oil. It is an object of the present invention to provide a continuous carbonization pyrolysis and oil conversion apparatus for plastics, from which oil is efficiently separated.

[0004]

That is, the present invention relates to a hopper for charging plastic to be processed and a lower portion thereof,
A first screw feeder whose outer periphery is enclosed and which has a thin front end in the traveling direction for compressing and transporting the plastic to be processed, and a rear end connected to the front end of the first screw feeder to melt the plastic to be processed; And a second screw feeder of a horizontal type having an outer periphery surrounded for dechlorination, a first heating furnace surrounding at least a part of the second screw feeder, and necessary for melting into the first heating furnace. For circulating an inert gas having a temperature,
A first heating device having a volatile gas detector;
An inclined third screw feeder having a rear end connected to the tip of the screw feeder, and an outer periphery for thermally decomposing the plastic to be treated which is thermally decomposed in a low temperature range; and the third screw feeder. A second heating furnace surrounding the outer periphery of the second heating furnace, and a second heating device having a volatile gas detector for circulating and supplying an inert gas having a first-stage pyrolysis temperature to the second heating furnace. An inclined fourth screw feeder having a rear end connected to the tip of the third screw feeder, and an outer periphery for thermally decomposing the plastic to be treated which is thermally decomposed in a high temperature range; A third heating furnace surrounding the outer periphery of the screw feeder of No. 4, and circulating supply of an inert gas having a second stage pyrolysis temperature higher than the first stage pyrolysis temperature to the third heating furnace. The third with volatile gas detectors
Heating device, the third screw feeder and the fourth
A cooler connected to a communication pipe connected near the upper end of the screw feeder, a first gas-liquid separator, and a second gas separator for separating heavy oil from liquid extracted from the lower part thereof. A second gas-liquid separator, a vacuum pump for extracting a gas component from the upper portion of the second gas-liquid separator, and a third gas-liquid separator for cooling the gas and condensing a light oil component. It is characterized by comprising.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a continuous dry distillation pyrolysis oil conversion device for plastics of the present invention. The apparatus comprises a compression section 1, a melting section 20, and a first disassembly section 4.
0, a second disassembly section 60 and a separation section 80. The compression section 1 is a section in which the crushed plastic pieces are charged from a charging hopper 2 into a first horizontal screw feeder 3 and compressed at room temperature while being conveyed. More specifically, the horizontal first screw feeder 3 is configured such that an outer periphery of a screw 4 driven by a motor Ml is surrounded by a tube 5,
The upper part of the rear end of the tube 5 in the traveling direction is partially open, and the opening 6 communicates with the charging hopper 2 for storing the crushed plastic pieces. Since the pipe body 5 gradually becomes thinner toward the leading end in the traveling direction, the plastic crushed pieces supplied from the charging hopper 2 to the first screw feeder 3 are compressed while being transported in the traveling direction. Here, since the plastic is sufficiently compressed, a rapid decrease in volume can be prevented even when the plastic is melted in the melting section 20 next time.

The melting section 20 is a section where the plastic conveyed from the first screw feeder 3 is preliminarily melted and dechlorinated by the first heating device 22 while the plastic is conveyed by the second screw feeder 21. is there. The second screw feeder 21 for horizontal melting has a screw 2 driven by a motor M2 having an outer circumference of a tube 2.
The upper part of the rear end of the tube 24 in the traveling direction is partially open, and the second screw feeder 21 is at least partially covered by a first heating furnace 25.

The first heating device 22 includes a heat exchanger 26, a blower 27, an inert gas closed system 28 provided with a volatile gas detector 30, and a hot air generator 29 for supplying hot air for heating to the heat exchanger. Provided, the first heating furnace 2
5, a circulating heated inert gas having a temperature necessary for melting is circulated and supplied from upstream to downstream from the downstream of the feeder. The hot air generator 29 converts the plastic crushed pieces inside the second horizontal screw feeder 21 into the heating furnace 2.
Heating can be performed so as to raise the temperature to about 250 ° C. in the five portions, and it is desirable that the heating can be performed at a temperature gradient of about 100 ° C. in the rear end portion in the traveling direction.

The tube 24 of the second screw feeder 21 penetrating through the heating furnace 25 is extended to a first disassembling section 40.
Is connected to the rear end of the pipe body 42 of the third screw feeder 41 for disassembly. It is desirable that the front end of the screw 23 inside the second screw feeder 21 terminates at a position midway away from the front end connected to the third screw feeder 41. An opening 32 communicating with the chlorine gas treatment facility 31 is formed in the tube 24 at this midway position. An inert gas flows from another opening 33 of the tube 24.

In the melting section 20, the plastic to be processed is preheated to about 250 ° C. by the heating furnace 25 while being conveyed by the second screw feeder 21. In this preheating state, the plastic becomes a liquid or a gel. At this time, chlorine contained in, for example, PVC (vinyl chloride resin) in the plastic and chlorides adhering to other plastics are gasified to form chlorine gas.
Here, at the front end of the second screw feeder 21, the screw 23 terminates in the middle of the tube 24, so that the front end inside the second screw feeder 21 is closed by the melted plastic. That is, the chlorine gas is discharged to the outside through the opening 32 at the rear thereof, and is processed by the chlorine gas processing equipment 31 communicating therewith. Further, the plastic that melts and closes the front end inside the second screw feeder 21 can prevent a blowout phenomenon in which air flows into the first disassembling section 40 through the conduit 34. .

In the above-described embodiment, the opening 32 of the tube 24 is connected to the chlorine gas treatment facility 31. When the plastic is put into the hopper 2, a neutralizing agent such as quicklime is mixed at the same time. When chlorine gas is separated in the tube 24, the chlorine gas reacts with the neutralizing agent to form a stable form such as calcium chloride, which can be finally recovered as a residue. Such chlorine gas processing equipment can be omitted. The inert gas flowing from the opening 33 and the inert gas circulated and supplied to the heating furnace may be those usually used, for example, nitrogen gas is preferable.

In the first disassembly section 40, a screw 43 for transporting the plastic upward over substantially the entire length thereof is disposed inside a pipe 42 of a third screw feeder 41 for inclined disassembly. The screw 43
Is driven by a motor M3 which is hermetically mounted so that air does not enter the upper part of the tube 42 outside the tube 42. The outer peripheral portion of the third screw feeder 41 and the portion where the second screw feeder 21 extends from the first heating furnace 25 toward the first decomposition section 40 are surrounded by the second heating furnace 44.

The second heating device 45 communicating with the second heating furnace 44 includes a heat exchanger 46 and a heat exchanger 46, like the first heating device 22.
The system is equipped with a blower 47, an inert gas closed system 48, a hot air generator 49 for supplying hot air for heating to a heat exchanger, and a volatile gas detector 50. Circulating heated inert gas with
The screw feeder 41 is circulated and supplied upstream and downstream from downstream and forward. In this hot air generator 49, the maximum temperature at the upper end of the third screw feeder 41 is 4
The temperature can be set so as to be 00 ° C. and the maximum temperature at the lower end is 350 ° C. Further, the vicinity of the upper end of the pipe body 42 of the third screw feeder 41 is opened up and down, and the upper opening is communicated with the cooler 81 of the separation section 80 through a pipe line 51, preferably through a dechlorination tank 52. The lower opening communicates with the rear end of the pipe body 62 of the fourth screw feeder 61 of the second disassembly section 60 through the pipe 53.

Here, the operation of the first disassembling section 40 will be described. Plastics dissolved in a gel state and staying at the front portion of the screw 23 of the second screw feeder 21 are sent one after another. It is pushed forward by the gel-like plastic and is fed into the third screw feeder 41 of the first disassembly section 40. Then, while the plastic moves upward inside the third screw feeder, the outside of the screw feeder is heated from above to below by hot air having a mixing gradient of, for example, a maximum of 400 ° C. to 350 ° C. Of various plastics, including PVC liquefied in the melting part 20, urea resin, polyurethane resin, phenol resin,
A methacrylic resin or a resin that gasifies at a relatively low temperature, such as polystyrene, is gradually pyrolyzed and gasified at a specific pyrolysis temperature due to a difference in pyrolysis temperature even in a mixed state. In addition, the third screw feeder 41 is disposed at an angle, and when the feeder is heated from above to below, the plastic inside is gradually heated to a higher temperature as it moves upward. It is simple, is less likely to carbonize because it is gradually gasified from the bottom, and has good oiling efficiency.

The gas generated by decomposition in the third screw feeder is guided from an opening near the upper end of the screw feeder through an upper pipe 51 to a dechlorination tank 52. On the other hand, the residual plastic that has not been decomposed in the first decomposing unit 40 is sent to the second decomposing unit 60 through the lower conduit 53.

The second disassembly section 60 has a fourth screw feeder 61 of the same inclination type as the first disassembly section, and this fourth screw feeder is similar to the first disassembly section.
It has a tube 62, a screw 63, and a motor M4, and is surrounded by a third heating furnace 64. The second heating device 65 communicating with the third heating furnace 64 has the same structure as the first disassembly unit,
A heat exchanger 66, a blower 67, an inert gas closed system 68, a hot air generator 69 for supplying hot air for heating to the heat exchanger, and a volatile gas detector 70 are provided. The circulation heating inert gas having a temperature required for the second-stage thermal decomposition, which is higher than that of the fourth screw feeder 61, is circulated and supplied upstream from downstream to downstream. In the hot air generator 69, the maximum temperature at the upper end of the fourth screw feeder 61 can be set to 500 ° C., and the maximum temperature at the lower end can be set to 450 ° C. Further, the vicinity of the upper end of the pipe body 62 of the fourth screw feeder is opened vertically, and the upper opening is formed by the pipe 71, preferably through the dechlorination tank 51 on the upstream side, inside the separation section 80 on the downstream side. The lower opening is communicated with the cooler 81 and the lower opening is connected to the residue tank 7 by the residue motor 73 through the line 72.
It is in communication with 4.

In the second disassembling section 60, the first disassembling section 40
The remaining plastic not decomposed in the above is received into the inside of the fourth screw feeder 61 through the pipe 53 at the lower end, and the residual plastic is conveyed upward by the rotation of the screw 63. In the fourth screw feeder 61, from the upper end to the lower end, for example, 500
When heated at a temperature gradient from ℃ to 450 ℃, a resin such as polypropylene or polyethylene, which undergoes gas decomposition at high temperature, can be slowly decomposed and gasified. Thereby, even if the plastics to be processed are various kinds of resins having different thermal decomposition temperatures, it can be efficiently thermally decomposed.

Residues that do not melt, such as metal and sand, and calcium chloride added as quicklime to the melting section 20 for dechlorination and combined with chlorine are supplied to the fourth screw feeder 61.
From the upper part through the pipe 72 and the residue motor 73
As a result, the water enters the water in the residue tank 74 and is sealed with water. By this water seal, the fourth screw feeder 61
Even if a crack or the like is formed in the outer peripheral portion surrounding the container, the water-sealed residue tank 74 functions as a safety valve, so that a fire or an explosion can be prevented. Also, even if volatile gas leaks from the tubes of the second to fourth screw feeders 21, 41, 61,
The operation can be stopped suddenly by the volatile gas detectors 30, 50, 70 to prevent explosion and combustion.

The cooler 81 of the separation unit 80 includes a first gas-liquid separator 82, a second gas-liquid separator 83 for separating heavy oil from liquid extracted from the lower part thereof, A vacuum pump 84 for extracting a gas component from the upper portion of the second gas-liquid separator and a third gas-liquid separator 85 for cooling the gas component and condensing the light oil component are communicated with each other. . In addition, the second gas-liquid separator 83 and the third gas-liquid separator 8
The lower part of 5 communicates with a heavy oil recovery tank 86 and a light oil recovery tank 87, respectively. The upper portions of the first gas-liquid separator 82 and the third gas-liquid separator 85 communicate with exhaust gas treatment equipment (not shown). The gas generated by the gas decomposition of the first decomposition section 40 and the second decomposition section 60 are both led to the separation section 80 via the dechlorination tank 52 and liquefied, and the generated oil is separated into heavy oil and light oil. Recovery tanks 86 and 8
It is taken out to 7.

[0019]

According to the apparatus for continuously pyrolyzing and cracking plastics of the present invention, even if cracks or the like occur on the outer periphery surrounding the screw feeder, the water seal in the pipeline acts as a safety valve. In addition, the operation can be stopped suddenly by the volatile gas detector in the inert gas closed system to prevent explosion and combustion, etc., and can be used safely. Further, since the plastic to be treated is first compressed at room temperature and then melted by the second screw feeder, the occurrence of blowout can be suppressed. Further, by using three gas-liquid separators, heavy oil and light oil having good separability can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a continuous dry distillation pyrolysis oil conversion device for plastics of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compression part 2 Input hopper 3 First screw feeder 4 Screw 5 Tube 6 Opening 20 Melting part 21 Second screw feeder 22 First heating device 23 Screw 24 Tube 25 First heating furnace 26 Heat exchanger 27 Blower 28 Inert gas closed system 29 Hot air generator 30 Volatile gas detector 31 Chlorine gas treatment facility 32 Opening 33 Opening 34 Pipeline 40 First decomposition section 41 Third screw feeder 42 Pipe 43 Screw 44 Second heating furnace 45 Second heating device 46 Heat exchanger 47 Blower 48 Inert gas closed system 49 Hot air generator 50 Volatile gas detector 51 Pipe line 52 Dechlorination tank 53 Pipe line 60 Second decomposition section 61 Fourth screw feeder 62 Tube 63 Screw 64 Third Heating furnace 65 Third heating device 66 Heat exchanger 67 Blower 68 Inert gas closed system 69 Hot air generator 70 Volatile gas detector 71 Pipe line 72 Pipe line 73 Residue motor 74 Residual tank 80 Separator 81 Cooler 82 No. 1 gas-liquid separator 83 Second gas-liquid separator 84 Vacuum pump 85 Third gas-liquid separator 86 Heavy oil tank 87 Light oil tank M1, M2, M3, M4 Motor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D004 AA07 CA03 CA04 CA24 CA32 CB13 CB16 CB28 CB33 CB42 CB50 DA01 DA03 DA06 DA20 4F301 AA15 AA17 AA20 AA22 AA29 CA09 CA26 CA45 CA72 4H012 HB05 4H029 CA01 CA07 CA14

Claims (10)

[Claims] 1. A hopper for charging plastic to be treated,
The first part for compressing and transporting the plastic to be processed, which communicates with its lower part, is surrounded at the outer periphery, and has a narrow horizontal end portion in the traveling direction.
And a horizontal second screw feeder having a rear end connected to a front end of the first screw feeder for melting and dechlorination of the plastic to be processed, and having an outer periphery surrounded by at least the second screw feeder. A first heating furnace surrounding a part of the second screw feeder, and a first heating furnace for circulating and supplying an inert gas having a temperature necessary for melting to the first heating furnace.
A first heating device having a volatile gas detector, a rear end portion connected to a front end of the second screw feeder, and an outer periphery for thermally decomposing the plastic to be thermally decomposed in a low temperature range is enclosed. Inclined third screw feeder, a second heating furnace surrounding the outer periphery of the third screw feeder, and a first heating furnace to the second heating furnace.
A second heating device having a volatile gas detector for circulating and supplying an inert gas having a thermal decomposition temperature of the stage; and a rear end portion connected to the front end of the third screw feeder, An inclined fourth screw feeder surrounding the outer periphery for thermally decomposing the plastic to be thermally decomposed, a third heating furnace surrounding the outer periphery of the fourth screw feeder, and the third heating A third heating device having a volatile gas detector for circulating and supplying an inert gas having a second stage pyrolysis temperature higher than the first stage pyrolysis temperature to the furnace; and the third screw A cooler connected to a communication pipe connected near the upper end of the feeder and the fourth screw feeder, a first gas-liquid separator, and a heavy oil component from a liquid component extracted from a lower portion thereof. Separate Gas-liquid separator, a vacuum pump for extracting gas from the upper part of the second gas-liquid separator, and a third gas-liquid for cooling the gas and condensing the light oil component An apparatus for continuously cracking and pyrolyzing plastics, comprising: a separator; 2. The first to third heating devices each include a heat exchanger, a blower, an inert gas closed system, and a hot air generator for supplying hot air for heating to the heat exchanger. The continuous carbonization pyrolysis oil conversion apparatus for plastics according to claim 1. 3. A screw disposed inside the second screw feeder terminates at a position halfway away from a distal end portion where the first screw feeder is connected to the third screw feeder. 3. The continuous pyrolysis pyrolysis oil conversion device for plastics according to claim 1 or 2. 4. The continuous pyrolysis-oil cracking apparatus for plastics according to claim 3, wherein a part of the outer periphery of said second screw feeder is opened at said intermediate position and communicates with a chlorine gas treatment apparatus. 5. The continuous carbonization heat of plastics according to claim 1, wherein an upper portion of the fourth screw feeder is connected to a residue tank by a communication pipe extending downward and is water-sealed. Cracking unit. 6. The third screw feeder and a fourth screw feeder.
The apparatus for continuously cracking and pyrolyzing plastics according to any one of claims 1 to 5, wherein a dechlorination tank is provided between the communication pipe and the cooler connected near the upper end of the screw feeder. 7. The continuous pyrolysis pyrolysis of plastics according to claim 1, wherein the inert gas is circulated and supplied from upstream to downstream of each of the second to fourth screw feeders from downstream to downstream. apparatus. 8. The continuous dry distillation pyrolysis of plastics according to claim 1, wherein the first heating device raises the plastics in the second screw feeder to about 250 ° C. apparatus. 9. The apparatus according to claim 2, wherein the second heating device raises the temperature of an upper end and a lower end of a second heating furnace surrounding an outer periphery of the third screw feeder to about 400 ° C. and 350 ° C., respectively.
9. The apparatus for continuously carbonizing and pyrolyzing and cracking plastics according to claim 1, wherein the apparatus is set to a degree. 10. The third heating device is configured to raise the temperature of an upper end and a lower end of a third heating furnace surrounding the outer periphery of the fourth screw feeder to about 500 ° C. and 450 ° C., respectively.
10. The continuous dry distillation pyrolysis oil conversion device for plastics according to claim 1, wherein the temperature is set at about ° C.