JP2006056957A - Apparatus for converting waste plastic into oil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve recovery efficiency of reclaimed oil in an apparatus for converting waste plastics into oil by thermally decomposing waste plastics. <P>SOLUTION: The apparatus for converting waste plastics into oil has a storage hopper 10, an extruder 20 for melting and extruding chips of waste plastics, a thermal decomposition furnace 30 for thermally decomposing molten waste plastics, a catalytic reaction vessel 40 for decomposing decomposition gas into light oil fraction gas, condensers 50 and 60 for liquefying the light oil fraction gas to give reclaimed oil, a reclaimed oil tank 70 for recovering the reclaimed oil obtained by the condenser 60, a centrifugal separator 80, a reserve tank 90, a scrubber 100 for collecting fine particles in off-gas, a water seal 110 for passing the off-gas, etc., through sealing water and an adsorption type deodorization furnace 120. The sealing water 114 is stored in a water seal main body 111 and the off-gas is passed through the sealing water 114 and introduced from the scrubber 100 into the adsorption type deodorization furnace 120. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a waste plastic oil processing apparatus that obtains recycled oil from waste plastic, and more specifically, relates to a waste plastic oil processing apparatus that can efficiently produce recycled oil by providing a water seal in the final stage. Is.

  Conventionally, as one type of plastic recycling equipment, there is known a waste plastic oil processing equipment that industrially produces high quality light oil by pyrolyzing waste plastic such as thermoplastic containers and shopping bags. Yes.

  Examples of the waste plastic oil converting apparatus include a pyrolysis furnace that thermally decomposes waste plastic to generate a cracked gas, and a catalytic reaction that decomposes the cracked gas generated in the pyrolysis furnace into a light oil fraction gas. A tank and a condenser for liquefying the light oil distillate gas generated in the catalytic reaction tank to obtain regenerated oil. After the waste plastic is pyrolyzed in a pyrolysis furnace, the decomposition generated by this pyrolysis The gas was brought into contact with the catalyst in the catalytic reaction tank and decomposed into light oil fraction gas, and this light oil fraction gas was liquefied with a condenser to obtain regenerated oil.

  By the way, in such a waste plastic oil processing apparatus, the cracked gas generated in the thermal cracking furnace is decomposed into light oil fraction gas in the catalytic reaction tank and then liquefied in the condenser to become regenerated oil. Part of the gas is generated that does not liquefy at normal temperature (hereinafter referred to as “off-gas” (including styrene monomer, xylene, toluene, methane, ethane, ethylene, propane, butane, propylene, etc.)). Such off-gas must be deodorized because it has a strange odor, and the off-gas from the condenser has been introduced into a direct combustion deodorization furnace or an adsorption deodorization furnace using activated carbon to deodorize it.

  Since the risk of explosion when the off-gas flows backward increases, conventionally, the off-gas is attracted into the deodorizing furnace by a blower or the like at a constant pressure (see, for example, Patent Document 1).

JP 2003-301185 A

  However, in the conventional waste plastic oil processing apparatus described above, the off-gas in the condenser is introduced into the deodorizing furnace by attracting it at a constant pressure. Light oil distillate gas was also forcibly attracted into the deodorization furnace, and there was a problem that the production efficiency of reclaimed oil was low.

  An object of the present invention is to provide a waste plastic oil treatment apparatus capable of solving the above problems and improving the production efficiency of recycled oil.

  The inventors of the present invention diligently studied to solve the above-mentioned problems, and found that a water-sealing seal was provided in the final treatment stage of off-gas, thereby achieving an extremely efficient oil conversion treatment, and completed the present invention. It is.

  That is, the waste plastic oil treatment apparatus according to the present invention includes a pyrolysis furnace that pyrolyzes waste plastic to generate cracked gas, and a catalyst that cracks the cracked gas generated in the pyrolysis furnace into light oil fraction gas. A waste plastic oil processing apparatus having a reaction tank and a condenser for liquefying light oil distillate gas generated in the catalyst reaction tank to obtain regenerated oil, wherein a water seal is connected to an off-gas pipe of the capacitor It is configured as a feature.

  In the waste plastic oil processing apparatus according to the present invention, by connecting a water seal to the off gas pipe of the capacitor, the off gas in the capacitor is attracted to the outside of the capacitor through the water seal. Therefore, the inside of the condenser is at a normal pressure, preventing the light oil fraction gas from escaping, and the cracked gas stays in the catalytic reaction tank for a long time, thereby improving the light oil fraction gas generation efficiency. As a result, the amount of recovered oil can be greatly increased. Furthermore, since the off-gas rate can be reduced (less than 1%), it is no longer necessary to provide a deodorizing furnace because there is no odor.

  The waste plastic oil processing apparatus by this invention has connected the water seal to the off-gas pipe | tube of a capacitor | condenser. The water seal may be directly connected to the off-gas pipe of the condenser, but is usually connected via a processing device such as a scrubber. The water-sealed seal is designed so that off-gas can be introduced into the water stored in the water-sealed seal body through an off-gas pipe, and only the off-gas that has passed through the water is introduced into the next process (for example, a deodorizing furnace). is there. That is, the inside can be brought to a substantially normal pressure in each process upstream of the water seal. As long as the water seal can store a predetermined amount of water, the shape of the water seal main body (for example, a round cylindrical shape or a square cylindrical shape) is not particularly limited.

  It is preferable that the height of the water column in the water seal main body of the water seal (the length to the surface of the off-gas pipe and the water) can be adjusted within a range of 40 to 500 mm. For example, water is added to the bottom of the water seal main body. A water discharge pipe provided with a water discharge valve for discharging is connected, and a water supply pipe provided with a water supply valve for supplying water is connected to the top of the water seal main body. .

  Further, the height of the water column is preferably 40 to 500 mm, more preferably 50 to 300 mm, and most preferably 80 to 200 mm. If the height of the water column is less than 40 mm, the water-sealed seal is easily broken when off-gas bubbles, and if the height of the water column exceeds 500 mm, the pressure is more than necessary, so it is slightly higher than normal pressure. Is preferably in the range of + about 390 Pa to + about 4900 Pa.

  In addition, the water seal in the present invention is not limited to those using water, and includes those using other liquids having no flammability (flammability). Further, the height of the liquid column is a value converted so as to be a pressure equivalent to the pressure of the water value described above.

  Examples of the waste plastic used in the waste plastic oil processing apparatus according to the present invention include polyethylene terephthalate, polyethylene, polypropylene, and polystyrene. Examples of the form include bottles, sheets, and films.

  An embodiment of a waste plastic oil converting apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the entire waste plastic oil processing apparatus, and FIG. 2 is a schematic view showing a water seal.

  In FIG. 1, 10 is a storage hopper for storing waste plastic chips, 20 is an extruder for melting and extruding waste plastic chips charged from the storage hopper 10, and 30 is a molten waste plastic supplied from the extruder 20. A pyrolysis furnace for pyrolysis, 40 is a catalytic reaction tank for decomposing the cracked gas supplied from the pyrolysis furnace 30 into light oil fraction gas, and 50 is a liquefaction of the light fraction gas supplied from the catalyst reaction tank 40. A first condenser 60 for obtaining regenerated oil, a second condenser 60 for liquefying the light fraction gas supplied from the first condenser 50 to obtain reclaimed oil, and a regenerated oil 70 obtained by the first condenser 50 and the second condenser 60. Is a recovered oil tank, 80 is a centrifuge that removes impurities from the recycled oil sent from the recovered oil tank 70, and 90 is sent from the centrifuge 80 A reserve tank that stores regenerated oil from which pure substances have been removed, 100 is a scrubber that collects fine particles in off-gas sent from the second condenser 60, 110 is a seal for off-gas sent from the second condenser 60, etc. A water-sealed seal 120 that passes through water is an adsorption-type deodorizing furnace that deodorizes off-gas sent from the water-sealed seal 110.

  The storage hopper 10 is connected to an inlet of the extruder 20 and continuously inputs waste plastic chips. The extruder 20 is provided with a pressure sensor (not shown) for detecting the discharge pressure. Further, a connecting pipe 21 is connected to the outlet, and the other end of the connecting pipe 21 is connected to the pyrolysis furnace 30, and valves 22 and 23 driven by an air actuator are provided in the middle of the connecting pipe 21. It has been.

  The connecting pipe 21 rises upward from the outlet of the extruder 20 and is then connected to the pyrolysis furnace 30. The rising height h of the connecting pipe 21 is set in a range of 2000 to 3000 mm. Yes.

  The pyrolysis furnace 30 is provided with a pyrolysis kettle 31 for thermally decomposing the molten waste plastic and a combustion furnace 32 for heating the pyrolysis kettle 31, and the connecting pipe 21 is attached to the top plate of the pyrolysis kettle 31. It is connected. An agitator 33 for agitating the molten waste plastic is provided inside the pyrolysis kettle 31, and a pressure sensor 34 for sensing the pressure in the pyrolysis kettle 31 is provided, and the temperature in the pyrolysis kettle 31 is detected. A temperature sensor 35 is provided.

  Further, a nitrogen pipe 36 for supplying nitrogen is connected to the pyrolysis vessel 31, and this nitrogen pipe 36 is connected to a nitrogen gas source (not shown) such as a nitrogen gas tank via a nitrogen flow rate monitoring device 37. Has been. A nitrogen pipe 36 located upstream of the nitrogen flow rate monitoring device 37 is connected between the valve 22 and the valve 23 of the connecting pipe 21 so that nitrogen can be supplied to the connecting pipe 21. In addition, a cracking gas pipe 38 for sending the generated cracked gas to the catalytic reaction tank 40 is connected to the pyrolysis pot 31.

  The catalytic reaction tank 40 includes a reaction tank main body 41 and a heating unit 42 provided around the reaction tank main body 41. The cracked gas pipe 38 is connected to the reaction tank main body 41, and the generated light oil fraction is generated. A fraction gas pipe 43 for feeding the fraction gas to the first condenser 50 is connected. The heating unit 42 is connected to the combustion furnace 32 by an exhaust gas pipe 39 so that the exhaust gas of the combustion furnace 32 can be sent.

  The first condenser 50 is provided with a hot water machine 51 so as to be heated. A first recovered oil pipe 52 for sending liquefied recycled oil to the recovered oil tank 70 is connected. The first recovered oil pipe 52 is connected to a portion of the first recovered oil pipe 52 near the outlet of the first condenser 50. In order to remove solid matter (such as terephthalic acid) adhering to the inner surface, water vapor supply means 53 for blowing water vapor into the pipe is provided. Further, a distillate gas pipe 54 for feeding light oil distillate gas that has not been liquefied to the second condenser 60 is connected.

  The second capacitor 60 is cooled by a cooler 61. A plurality of second recovery oil pipes 62 for feeding the liquefied recycled oil to the recovery oil tank 70 are connected, and a portion of the second recovery oil pipe 62 near the outlet of the second condenser 60 is connected to the first recovery oil pipe 62. Similar to the oil pipe 52, a water vapor supply means 63 is provided. Further, an offgas pipe 64 for sending offgas to the scrubber 100 is connected. The scrubber 100 is provided with a water tank 101 for supplying water used for removing fine particles, and an offgas pipe 102 for feeding the collected offgas to the water seal 110 is connected.

  As shown in FIG. 2, the water seal 110 is provided with a cylindrical water seal main body 111, an off gas supply pipe 112 is connected to the lower part of the water seal main body 111, and an off gas discharge pipe 113 is connected to the upper part. Are connected, the off-gas supply pipe 112 is connected to the off-gas pipe 102 from the scrubber 100, and the off-gas discharge pipe 113 is connected to the adsorption-type deodorizing furnace 120. The tip of the off-gas supply pipe 112 enters the inside of the water-sealed seal main body 111, and the water-sealed seal main body 111 is filled with the sealing water 114 with the off-gas supply pipe 112 being buried, and the off-gas supply pipe 112 is sealed. The height H of the water column up to the surface of the water 114 is adjusted in the range of 40 to 500 mm.

  A water supply valve 115 for supplying seal water is connected to the top of the water seal main body 111, and a water discharge valve 116 for discharging seal water is provided at the bottom of the water seal main body 111. The seal water is connected to the water seal main body 111 through the water supply valve 115 and the seal water in the water seal main body 111 is discharged through the water drain valve 116 to The height of the water column of the seal body 111 can be set arbitrarily. Reference numeral 117 denotes a side glass. 1 is a blower for attracting off-gas.

  The recovered oil tank 70 is configured such that regenerated oil is sent from the first recovered oil pipe 52 and the second recovered oil pipe 62, and a regenerated oil pipe 71 for sending the regenerated oil to the centrifuge 80 is connected to the recovered oil tank 70. ing. The centrifuge 80 is connected to a regenerated oil pipe 81 for sending regenerated oil from which impurities have been removed to the reserve tank 90. The reserve tank 90 is connected to an oil feed pipe 91 for feeding regenerated oil to the burner of the combustion furnace 32, and a part of the recovered reclaimed oil is used for the combustion furnace 32. Further, an oil feed pipe 92 for feeding into a storage facility (not shown) such as a tank is connected.

  Next, the operation of the waste plastic oil converting apparatus as described above will be described.

  First, waste plastic (plastic container made of thermoplastic plastic, shopping bag, etc.) is crushed into chips and put into the storage hopper 10. The thrown-out waste plastic chips are supplied to the extruder 20, extruded in a melted state in the extruder 20, and supplied to the thermal decomposition pot 31 through the connecting pipe 21.

  At this time, the pyrolysis vessel 31 (capacity: 3.83 m 2) is filled with nitrogen from the nitrogen gas source via the nitrogen pipe 36 (total nitrogen filling amount: about 8 m 2) and is replaced with nitrogen. This nitrogen filling is performed by igniting the burner after filling with nitrogen for 10 minutes, and continuing the filling for 10 minutes after the ignition of the burner. Further, when the nitrogen flow rate is detected by the nitrogen flow rate monitoring device 37 and the nitrogen filling is not good due to clogging of the nitrogen pipe 36, the burner is not ignited.

  The molten waste plastic supplied to the pyrolysis kettle 31 is stirred by the stirrer 33 and heated and gasified in a state where the air is shut off, so-called dry distillation is performed. At this time, the discharge pressure of the extruder 20 is detected by a pressure sensor. When the discharge pressure decreases, the valves 22 and 23 are closed, the connecting pipe 21 is filled with nitrogen from the nitrogen gas source, and the burner is misfired. To do. Further, the pressure in the pyrolysis pot 31 is detected by the pressure sensor 34. When the pressure becomes lower than a predetermined pressure, the burner is misfired and further filled with nitrogen gas. On the other hand, when the pressure becomes higher than the predetermined pressure, the burner is misfired, and when the gasification progresses abnormally, the gas is discharged to the outside from the safety valve. Further, the temperature in the pyrolysis pot 31 is detected by the temperature sensor 35, and when the temperature becomes higher than a predetermined temperature, the burner is misfired.

  Moreover, even if the gas pressure in the thermal decomposition pot 31 becomes high, the portion where the connecting pipe 21 rises prevents the decomposition gas from flowing into the extruder 20.

  High-temperature cracked gas (mainly composed of hydrocarbons having about 1 to 25 carbon atoms) generated in the pyrolysis furnace 31 of the pyrolysis furnace 30 is sent to the catalytic reaction tank 40, where heavy oil gas molecules having a large number of carbon atoms are contained. Is broken into light oil gas molecules (light oil fraction gas) having a small number of carbon atoms to produce light oil fraction gas.

  The light oil fraction gas generated in the catalytic reaction tank 40 is first sent to the first condenser 50 to be liquefied to generate regenerated oil, recovered in the recovered oil tank 70, and not liquefied in the first condenser 50. The light oil fraction gas is sent to the second condenser 60 and liquefied, and is similarly recovered in the recovered oil tank 70.

  Further, although the off gas exists in the second capacitor 60, the water seal 110 is connected to the off gas pipe 64 for discharging the off gas of the second capacitor 60 through the scrubber 100. 60, the 1st capacitor | condenser 50, and the inside of the catalyst reaction tank 40 are not the pressure-reduced state like the past, but the state near normal pressure. Therefore, the light oil fraction gas that is not liquefied in the second capacitor 60 is very rarely sucked into the deodorization furnace 120 and can be reliably recovered as recycled oil. Also, in the catalytic reaction tank 40, the cracked gas stays for a long time and the contact time with the catalyst layer becomes longer, so that the generation efficiency of the light oily fraction gas is improved, and the first capacitor 50 and the second capacitor 60 Since the agglomerate increases, the amount of recovered oil is greatly increased.

  Since the temperature of the first recovery oil pipe 52 and the second recovery oil pipe 62 of the first condenser 50 and the second condenser 60 near the outlet of the condenser decreases, for example, when the PET bottle is decomposed as waste plastic, terephthalic acid May adhere as solids to the inner surface of the tube. Therefore, when a solid matter adheres, the attached solid matter is removed by spraying steam on the inner surface by the steam supply means 53 and 63.

  The recycled oil recovered in the recovered oil tank 70 is freed of impurities such as moisture and carbon by the centrifuge 80 and is sent to the reserve tank 90 as the final recycled oil. The reclaimed oil sent to the reserve tank 90 is sent to the storage facility, but part of it is sent to the burner of the pyrolysis kettle 31 to become fuel.

  The off gas sent from the second capacitor 60 to the water seal 110 via the scrubber 100 is sent to the adsorption deodorization furnace 120 through the seal water 114. The off gas has an off gas ratio of less than 1%. Therefore, it can be easily deodorized in the adsorption deodorizing furnace 120.

[Example 1]
In the waste plastic oil processing apparatus as described above, when the height H of the water column of the water seal 110 was 150 mm, the oil conversion efficiency (recovery efficiency) was 96% by weight and the off-gas amount was 1% by weight. . The oil production efficiency is defined as follows.
Oil conversion efficiency = {Recovered oil (weight) / Plastic (weight)} × 100

[Comparative Example 1]
In Example 1, when the same conditions were used except that no water seal was used, the oil production efficiency (recovery efficiency) was 90% by weight and the off-gas amount was 7% by weight.

[Example 2]
In Example 1, except that it was carried out by batch processing without using the extruder 20, the oil production efficiency (recovery efficiency) was 96% by weight and the off-gas amount was 1% by weight.

[Comparative Example 2]
In Example 2, when the same conditions were used except that a water seal was not used, the oil conversion efficiency (recovery efficiency) was 90% by weight, and the off-gas amount was 7% by weight.

  As described above, it was confirmed that the production efficiency of recycled oil was improved by providing a water seal. In addition, the waste plastic composition ratio in the present situation is high in polystyrene, and since the main component of polystyrene is styrene monomer, the oil conversion efficiency is good. Therefore, although the oil conversion efficiency is only 6% by weight, it is considered that if the ratio of polyethylene, polypropylene, etc. increases, a difference in oil conversion efficiency of 12 to 18% by weight will appear. The residue obtained by adding the oil conversion efficiency and the amount of off-gas is ink pigment, paper tube free carbon, and the like.

It is a whole lineblock diagram showing one embodiment of a waste plastic oil-ized processing device by the present invention. It is the schematic which shows the water seal used for the waste plastic oil-processing apparatus by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Storage hopper 20 Extruder 21 Connection pipe 30 Pyrolysis furnace 40 Catalytic reaction tank 50 1st capacitor | condenser 53 Water vapor | steam supply means 60 2nd capacitor | condenser 63 Water vapor | steam supply means 70 Recovery oil tank 80 Centrifugal separator 90 Reserve tank 100 Scrubber 110 Water seal 120 Adsorption type deodorization furnace

Claims (2)

A pyrolysis furnace that thermally decomposes waste plastic to generate cracked gas, a catalytic reaction tank that decomposes the cracked gas generated in the thermal cracking furnace into light oil fraction gas, and a light light generated in the catalyst reaction tank A waste plastic oil processing apparatus having a condenser for liquefying an oil fraction gas to obtain recycled oil, wherein a water seal is connected to an off-gas pipe of the capacitor. 2. The waste plastic oil converting apparatus according to claim 1, wherein the water seal can be adjusted within a range of a water column height of 40 to 500 mm.

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