JP2006002088A - Process and apparatus for treating pyrolysis gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent fine solids contained in the pyrolysis gas obtained with a pyrolyzer that thermally decomposes plastics from adhering to the inside of a distillation apparatus and the like. <P>SOLUTION: The pyrolysis gas flowing out of the pyrolyzer 1 is supplied to a condenser 6 to condensate high boiling point components, the condensed components running out of the condenser 6 are supplied to a first centrifuge 9 to separate the solids, and from the obtained oil a slight amount of the remaining solids is separated with a second centrifuge 10 to obtain a pure oil. Further, the solids-rich effluent that flows out of the first centrifuge 9 is fed to a third centrifuge 11, a slight amount of the oil is separated there, and the separated oil is returned to the first centrifuge 9 through a pipe k. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a method and apparatus for treating pyrolysis gas generated by a plastic pyrolyzer, and in particular, separates fine solids contained in the pyrolysis gas and adheres the solids inside a distillation apparatus or the like. The present invention relates to a processing method and a processing apparatus that prevent this.

  A large amount of plastics is discharged from factories and households, and there is a thermal decomposition method as a suitable method for recycling this waste plastic as a resource. This thermal decomposition method is a method in which waste plastic is heated and decomposed in the absence of oxygen, and oil is recovered by condensing the generated thermal decomposition gas with a condenser. The recovered oil is used as a fuel as it is, or is further refined by supplying the oil to a distillation apparatus and recovered as a monomer that becomes a plastic raw material.

  There are two types of pyrolyzers that perform thermal decomposition: a tank type and a tube type. A tank-type pyrolyzer is a cylindrical tank body with a conical bottom formed with a scraper for stirring and scraping residue. Although it is suitable for processing, continuous operation is also possible.

  The tube-type pyrolyzer performs thermal decomposition while passing molten plastic through an elongated reaction tube having a heating unit disposed around it, and is suitable for continuous operation. These pyrolyzers can be operated at both normal pressure and reduced pressure. For example, when pyrolyzing polystyrene, the pyrolyzer is reduced in pressure so that the proportion of by-products such as toluene and ethylbenzene generated during the pyrolysis can be suppressed. It is preferable to operate in a state. A method for operating the pyrolyzer in a reduced pressure state as described above is described in Patent Document 1, for example.

  Both the tank-type and tube-type pyrolyzers have a slight amount of fine solids such as inorganic dust contained in the raw material waste polystyrene and carbides generated during pyrolysis in the pyrolysis gas flowing out of the pyrolyzer. Although it is included, the solid content flowing out is generally larger in the tube type. In the tubular pyrolyzer, solids and residues are discharged together with the pyrolysis gas from the outlet of the elongated reaction tube.

  Therefore, in order to temporarily store the residue, a thermal decomposition residence tank having a diameter of about 3 to 5 times that of the reaction tube is often provided at the outlet portion of the reaction tube. A part of the solid content flowing out contained in the pyrolysis gas is captured and separated together with the residue in the pyrolysis residence tank. As such a thermal decomposition residence tank, for example, a thing aiming at the cyclone effect is proposed in Patent Document 2.

Japanese Patent Laid-Open No. 11-199875 Japanese Patent Laid-Open No. 2000-212571

  In both the tank-type pyrolyzer and the tube-type pyrolyzer, it is inevitable that fine solids remain in the outflowing pyrolysis gas. Even when a pyrolysis residence tank is provided, it is difficult to completely capture the solid content. Such a fine solid content adheres to equipment such as a distillation apparatus and a pump, peripheral piping, etc., and adversely affects heat conductivity and flowability.

  In order to remove the solid matter adhering to equipment and piping, it is necessary to periodically stop the operation and perform maintenance such as internal cleaning, but the continuous operation is interrupted each time, so the operating efficiency of the system decreases. . In order to avoid this problem, it is conceivable to install a spare sequence in parallel. However, in this case, both the installation cost and the operating cost increase, and this is not a preferable solution as a solution.

  Therefore, the present invention has an object to solve such a conventional solid matter adhesion problem, and an object of the present invention is to provide a new method for treating pyrolysis gas. Another object of the present invention is to provide a processing apparatus that can suitably carry out the processing method.

  The method for treating a pyrolysis gas of the present invention that solves the above-mentioned problems is a method for treating a pyrolysis gas containing fine solids obtained by a pyrolyzer that pyrolyzes plastic, wherein the pyrolysis gas is treated with the pyrolysis gas. Supply to condenser, where high-boiling components contained in pyrolysis gas are condensed, condensing component flowing out from condenser is supplied to solid-liquid separator, where solid content is separated from condensed component to obtain oil component (Claim 1).

  In the processing method, a first centrifuge can be used as the solid-liquid separator (claim 2).

In the processing method, in addition to the first centrifuge as the solid-liquid separator, at least one of a second centrifuge and a third centrifuge is used.
Supplying the condensed component to a first centrifuge where the solids are separated from the condensed component;
When using a second centrifuge, supply the effluent from the oil spill of the first centrifuge to the second centrifuge, where the effluent is separated into oil and solids,
When using a third centrifuge, by supplying the effluent from the solids outflow portion of the first centrifuge to the third centrifuge, where the effluent is separated into oil and solids,
An oil can be obtained (Claim 3).

  In the above processing method, when a second centrifuge is used, two or more second centrifuges are used, and the effluent from the oil outflow part of the first centrifuge is sequentially supplied to each second centrifuge. In the case of using a third centrifuge, two or more third centrifuges are used and separated from the solids outflow part of the first centrifuge. Can be sequentially supplied to each third centrifuge to separate the effluent into oil and solids, respectively.

  In the above processing method, while each second centrifuge or each third centrifuge is not performing a separation operation, the inside thereof is washed with a washing liquid, then dried, and residual oil that evaporates by drying is removed from the condenser. (Claim 5).

  In any of the above processing methods, when the operation of the pyrolyzer is stopped, the solid content adhering to the inside of the solid-liquid separation device can be removed by a drying operation (claim 6).

  Moreover, the pyrolysis gas processing apparatus of the present invention that solves the above-mentioned problems is an apparatus for processing a pyrolysis gas containing fine solids obtained by a pyrolyzer that pyrolyzes plastic, wherein the pyrolysis gas And a solid-liquid separation device that separates the solid content from the condensed component obtained by the condenser and obtains an oil content (Claim 7).

  In the processing apparatus, the solid-liquid separation device can be constituted by a first centrifuge (claim 8).

In the above processing apparatus, the solid-liquid separator is constituted by the first centrifuge, at least one of the second centrifuge and the third centrifuge, and the supply side of the first centrifuge is connected to the condenser. Connect to the condensate discharge side,
When installing the second centrifuge, connect the supply side of the second centrifuge to the oil outflow part of the first centrifuge,
When the third centrifuge is installed, the supply side of the third centrifuge can be connected to the solid content outflow portion of the first centrifuge (claim 9).

  In the above processing apparatus, when the second centrifuge is installed, two or more second centrifuges are installed, and a liquid level detecting means is provided for each, and the supply side of each second centrifuge is provided. When the liquid level detection signal of the liquid level detection means provided in any of the second centrifuges reaches a preset value when connected to the oil content outflow part of the first centrifuge via an automatic on-off valve. A control device for controlling to perform the separation operation by closing the automatic opening / closing valve provided in the second centrifuge, and when providing the third centrifuge, Two or more units are installed, each is provided with a liquid level detection means, and the supply side of each third centrifuge is connected to the solids outflow part of the first centrifuge via an automatic on-off valve, respectively. 3 The liquid level detection signal of the liquid level detection means provided in the centrifuge is preset. It can be in when it reaches, providing a controller for controlling to perform separation operation by closing the automatic opening and closing valve provided in the third centrifuge (claim 10).

  In the processing apparatus, a cleaning means and a drying means for cleaning the interior of each second centrifuge or each third centrifuge are provided, and each second centrifuge or each third centrifuge performs a separation operation. When the process is completed, the interior can be cleaned and dried (claim 11).

  In the processing method of the present invention according to claim 1, the fine solid content contained in the oil component is separated by separating the fine solid content contained in the condensed component flowing out from the condenser with a solid-liquid separator. It can be greatly reduced. For this reason, it is possible to prevent a large amount of solid content from adhering to the inside of the piping or distillation apparatus on the downstream side, and the system can be stably operated for a long period of time. Moreover, this processing method can remove solid content from oil, without interrupting the continuous operation of a pyrolyzer.

  In the said processing method, when using a 1st centrifuge as a solid-liquid separator as described in Claim 2, solid content can be isolate | separated rapidly and efficiently from a condensed component.

  In the above processing method, when at least one of the second centrifuge and the third centrifuge is used in addition to the first centrifuge as the solid-liquid separator, the first centrifuge is used. The effluent from the oil spillage of the separator, that is, the oil-rich effluent is separated into oil and solids by the second centrifuge, and the effluent from the solids spillage of the first centrifuge, ie, the solids Since the rich effluent can be separated into oil and solid by the third centrifuge, oil with extremely low solid content can be recovered with high efficiency.

  In the above processing method, as described in claim 4, when two or more second centrifuges or two or more third centrifuges are used and the separation operations are sequentially performed, The two-stage separation can be performed continuously without stopping the one centrifuge.

  In the above processing method, as described in claim 5, when each second centrifuge or each third centrifuge is not performing a separation operation, the inside thereof is washed with a washing liquid, dried, etc. The two-stage separation can be performed continuously while maintaining the separation performance of each second centrifuge or each third centrifuge optimally. Moreover, the recovery rate of oil can be further increased by returning the residual oil vapor generated during drying to the condenser.

  In any one of the above processing methods, when the operation of the pyrolyzer is stopped and the solid content adhering to the inside of the solid-liquid separator is removed by a drying operation, the pyrolysis is performed. It can prevent that the solid content adhering to the inside of each device constituting the solid-liquid separator is hardened while the operation of the vessel is stopped.

  Moreover, since the processing apparatus of this invention of Claim 7 is equipped with the solid-liquid separation apparatus which isolate | separates solid content from the condensing component obtained with the condenser, and obtains an oil component, the processing method of this invention is suitable. Can be implemented.

  In the said processing apparatus, when a solid-liquid separator is comprised with a 1st centrifuge as described in Claim 8, it can isolate | separate solid content from a condensed component rapidly and efficiently.

  In the above processing apparatus, as described in claim 9, in the case where the solid-liquid separator is an apparatus constituted by at least one of a first centrifuge, a second centrifuge, and a third centrifuge, An apparatus capable of recovering oil with extremely low content with high efficiency can be configured.

  In the processing apparatus, when two or more second centrifuges or two or more third centrifuges are installed as described in claim 10, the separation operation is performed by operating the automatic opening / closing valve. By switching automatically, it is possible to configure a device that can continuously perform two-stage separation without stopping the first centrifuge.

  In the above processing apparatus, when the cleaning means and the drying means for cleaning the inside of each second centrifuge or each third centrifuge are provided as described in claim 11, each second centrifuge or An apparatus capable of continuously performing two-stage separation while optimally maintaining the separation performance of each third centrifuge can be configured.

  Next, the best mode for carrying out the present invention will be described. FIG. 1 is a process flow diagram of a pyrolysis gas treatment apparatus according to the present invention. The present embodiment is an example in which a tube-type pyrolyzer is used as a plastic pyrolyzer, but the present invention can be similarly applied to a case where a tank-type pyrolyzer is used. In the following explanation, styrene polymers such as styrene homopolymers and styrene copolymers such as AS and ABS (hereinafter referred to as polystyrene) are thermally decomposed as plastics, but the present invention is suitable for thermal decomposition. The same applies to other plastics such as polyolefins such as polyethylene.

  In the figure, 1 is a tubular pyrolyzer, 2 is an elongated reaction tube, 3 is a heating unit disposed around the reaction tube 2, 4 is a supply unit, 5 is a heated gas generator, 6 is a condenser, and 7 is Depressurization device, 8 is a solid-liquid separation device, 9 is a first centrifuge, 10 is a second centrifuge, 11 is a third centrifuge, 12, 13 are waste containers, 14, 15, 16, 17, 18 is a pump, 19 is a first distillation apparatus, 19a is a reboiler, 20 is a second distillation apparatus, 20a is a reboiler, 21 is a hopper, 22 is an extruding part, 23 is a rotating screw, 24 is a driving part such as a motor, 25 is An on-off valve, 26 is a burner, 27 is an oil storage tank, a to u are pipes, and D1 and D2 are ducts.

  The reaction tube 2 is made of a straight or bent tube of metal having good heat transfer and heat resistance, such as a stainless steel tube, and its dimensions vary depending on the processing capacity and the object to be processed, but the diameter is usually about 50 mm to 200 mm and length. Is in the range of about 5 m to over a dozen m. The heating unit 3 arranged around the reaction tube 2 has a peripheral wall thermally insulated by a heat insulating material such as ceramic fiber or castable, and one of the ducts D1 connected to the heated gas generator 5 communicates with the other and heat exchange is performed on the other side. A duct D2 for discharging the later heated gas as exhaust gas communicates. The heated gas generator 5 has a combustion chamber and a burner 26 for burning gaseous fuel or liquid fuel, and liquid fuel such as heavy oil is supplied to the burner 26, and a low-boiling component is supplied as gaseous fuel as will be described later. You can also

  The supply device 4 heats and melts the finely pulverized waste polystyrene and supplies the obtained molten polystyrene to the reaction tube 2 of the pyrolyzer 1. The supply device 4 shown in FIG. 1 uses an extruder generally used for a plastic injection molding machine or an extruder having a similar structure, and includes a hopper 21 for introducing polystyrene and an extrusion section 22. The extrusion unit 22 includes a heating and melting unit that heats and melts polystyrene, and a cylinder extending from the heating and melting unit. A rotating screw 23 that pushes the molten polystyrene is disposed inside the cylinder, and the rotating screw 23 is rotated by a driving unit 24 such as a motor. Driven. In the hopper 21, an ultrasonic bridge breaker is provided as desired.

  The condenser 6 includes a cooling pipe through which cooling water flows, cools the pyrolysis gas flowing out from the thermal decomposer 1 by exchanging heat with the cooling pipe, condenses the high boiling point containing styrene, and discharges the condensed components. Is. Connected to the condenser 6 are a pipe b through which pyrolysis gas flows into the supply side, a pipe c through which condensed components are discharged from the discharge side, and a pipe d through which low-boiling components flow out from the discharge side. Is provided with a decompression device 7 such as a vacuum pump.

  In the present embodiment, the solid-liquid separator 8 is composed of a first centrifuge 9, a second centrifuge 10, and a third centrifuge 11. The first centrifuge 9 has a relatively large processing capacity, and the second centrifuge 10 and the third centrifuge 11 have a relatively small processing capacity. The first centrifuge 9 centrifuges the oil and solids contained in the condensed component supplied from the pipe c, and the oil-rich effluent separated from the pipe e flows out and is separated from the pipe f. A solid-rich effluent flows out.

  The second centrifuge 10 separates the oil-rich effluent from the oil spill part of the first centrifuge 9 into oil and solids, and the separated oil is sent from the pipe j to the oil reservoir 27 by the pump 14. The solid content discharged and separated is discharged from the pipe h to the waste container 12. The third centrifuge 11 separates the solid-rich effluent from the solid effluent portion of the first centrifuge 9 into oil and solids. The separated oil is transferred from the pipe k to the pipe c by the pump 15. It is discharged and returned to the supply side of the first centrifuge 9, and the separated solid content is discharged from the pipe i to the waste container 13. In addition, the waste containers 12 and 13 are installed with an internal volume of about 120% of the solid content discharged during an average time during which the pyrolyzer 1 is continuously operated.

  As will be described later, the second centrifuge 10 and the third centrifuge 11 are configured to perform washing and drying of the inside thereof after completion of the respective separation operations. Since it evaporates, the evaporated oil is returned to the condenser 6 through the pipe g. In FIG. 1, one second centrifuge 10 and one third centrifuge 11 are shown. However, as will be described later, two of these are provided, and each of them is alternately switched for separation operation. It is like that. However, it is also possible to provide three or more second centrifuges 10 and three or more third centrifuges 11 and switch them in order to perform the separation operation.

  FIG. 2 is a cross-sectional view showing an example of the first centrifuge 9. The first centrifuge 9 shown in FIG. 2 is a so-called “decanter type” centrifuge generally used for solid-liquid separation of sewage sludge. The centrifuge includes a cylindrical bowl 30 and a screw conveyor 31 disposed in the bowl 30. A driving pulley 33 is provided on a shaft 32 of the bowl 30. The driving pulley 33 is rotationally driven by a driving motor (not shown). Is done.

  A part of the shaft 34 of the screw conveyor 31 is a hollow part, a jet hole is formed in the peripheral wall of the hollow part, and the introduction pipe 35 is inserted from the end part. Further, a spiral blade 37 is provided on the outer periphery of the shaft 34, and a drive pulley 36 is connected to a portion extending to the outside of the shaft 34. The drive pulley 36 is rotationally driven by a drive motor (not shown). The inlet portion of the introduction pipe 35 constitutes the supply side of the condensed component to the first centrifuge 9.

  The bowl 30 is rotationally driven by a driving force from the driving pulley 33 at, for example, 1000 to 2000 rotations / minute, and the screw conveyor 31 is rotationally driven by the driving force from the driving pulley 36 with a slight rotational difference from the bowl 30. The condensed component to be separated is supplied from the right end of FIG. 2 to the inside of the shaft 35 as indicated by an arrow, and is ejected from the ejection hole into the inside of the bowl 30 through the hollow portion of the screw conveyor 31.

  Condensed components ejected into the bowl 30 are subjected to centrifugal force due to high-speed rotation, and are divided into oil and solid components. The oil components move to the left along the inner wall surface of the bowl 30, and are sent from the oil component outlet 38 to the pipe e. Spills as oil rich spill. On the other hand, the solid content pressed against the inner wall surface of the bowl 30 by centrifugal force is pushed by the spiral blades 37 of the screw conveyor 31 and moves to the right, and the solid content-rich effluent flows from the solid content outflow portion 39 to the pipe f. As spills.

  FIG. 3 is a process flow diagram specifically showing the peripheral portion of the second centrifuge 10. (In the case of the third centrifuge 11 as well, the second centrifuge 10 and its peripheral portion shown in FIG. 3 are similarly configured.) The second centrifuge 10 includes the second centrifuge 10a and the second centrifuge 10. Two centrifuges 10b are connected in parallel. The second centrifuge 10a and the second centrifuge 10b are configured in the same manner, and the separation capacity is about 50 to 60% of the separation capacity of the first centrifuge 9.

  The second centrifuges 10a and 10b include a cylindrical and vertical casing 50, a heating unit 51 such as an electric heater provided outside the casing 50, and a fine mesh (preferably the most mesh value) arranged rotatably inside. (For example, 440 mesh) having a cylindrical stainless steel screen container. The heating unit 51 constitutes a drying means. The second centrifuges 10a and 10b can be used by vertically placing a commonly used central axis rotating cylindrical type.

  A pipe e for introducing oil-rich effluent from the first centrifuge 9 communicates with the supply side at the upper part of the casing 50, and an automatic on-off valve 53 such as an electromagnetic valve is provided in the pipe e. In addition, a pipe g for discharging the residual oil that evaporates communicates with the upper portion of the casing 50, and a pipe j for discharging the separated oil is in communication with the automatic opening / closing valve 54 and the pump 14. The pipe j, the automatic on-off valve 54, and the pump 14 constitute oil discharge means for the second centrifuges 10a and 10b. On the other hand, the lower part of the casing 50 is tapered to reduce its cross section, and a pipe i for discharging the separated solid content to the waste container 12a (12b) communicates with the bottom part, and an automatic opening / closing valve 60 is provided in the pipe.

  Connected to the second centrifuges 10a and 10b are a pipe r for supplying a cleaning liquid for dissolving oil, for example, a styrene solution, from the cleaning liquid tank 55, and a pipe s for returning the cleaning liquid to the cleaning liquid tank 55. An automatic opening / closing valve 57 is provided. A clean styrene solution is replenished to the cleaning liquid tank 55 through the pipe t provided with the automatic opening / closing valve 63, and the cleaning liquid dirty by the cleaning is discharged from the cleaning liquid tank 55 through the pipe u provided with the automatic opening / closing valve 62. It is supplied to the burner 26 of the heated gas generator 5 as liquid fuel. The cleaning liquid tank 55, the pipe r, the pipe s, the pump 56, the automatic open / close valve 57, and the like constitute a cleaning means.

  The second centrifuges 10 a and 10 b are provided with a liquid level detection means 58 for detecting the liquid level of the oil component, and a liquid level detection signal of the liquid level detection means 58 is input to the control device 59. Various control signals as described later are output from the control device 59 to the automatic electromagnetic valves 53, 54, 57, the pumps 14, 56, and the like. The control device 59 is constituted by a computer device, for example, and various controls are executed by a control program stored in the storage unit.

  The process flow of FIG. 3 is also applied to the third centrifuge 11 as described above. In the case of the third centrifuge 11, the solid content outflow portion 39 of the first centrifuge 9 is provided on the supply side. Is connected, and the oil component flowing out from the oil component outflow side returns to the first centrifuge 9 from the piping k (and the pump 15 (not shown)) indicated by the dotted line via the piping c.

  In FIG. 1 again, the oil storage tank 27 is connected to a pipe 1 provided with a pump 16, and the tip of the pipe 1 communicates with the middle stage of the first distillation apparatus 19. A reboiler 19a is provided at the bottom of the first distillation apparatus 19, a pipe m that flows out low-boiling components such as toluene and ethylbenzene communicates with the upper part, and a pipe n that flows out high-boiling components containing styrene communicates with the lower part, A pump 17 is provided in the pipe n. The tip of the pipe n communicates with the middle stage of the second distillation apparatus 20.

  A reboiler 20a is provided at the bottom of the second distillation apparatus 20, and a pipe o through which a low-boiling point component made of styrene flows out communicates with the top, and the tip of the pipe o communicates with a styrene recovery tank (not shown). A pipe p through which a high-boiling component (heavy oil) including styrene trimer and dimer flows out communicates with the lower part of the second distillation apparatus 20, and a pump 18 is provided in the pipe p. The tip of the pipe p communicates with a heavy oil recovery tank (not shown).

  A duct D2 is connected to the reboilers 19a and 20a from the heating unit 3 via the thermal decomposer 1, and the exhaust gas becomes a heating source for the reboilers 19a and 20a. In addition, the 1st distillation apparatus 19 and the 2nd distillation apparatus 20 can use the general distillation tower which filled the multistage shelf or the lashing.

  Next, a method for treating the pyrolysis gas by the process flow will be described. First, preparations are made for the operation of the pyrolysis system and distillation system. First, the heated gas generator 5 is operated to supply a heated gas of about 800 ° C. to 1000 ° C. to the heating unit 3 of the pyrolyzer 1, and the inside of the reaction tube 2 is about 600 to 800 ° C. which is the thermal decomposition temperature of polystyrene. The temperature is raised to Further, the decompression device 7 is operated to discharge the internal air of the molten polystyrene system and the pyrolysis gas system to be in the absence of oxygen, and the pressure in the system is reduced to, for example, about 2 kPa to 10 kPa. At that time, the on-off valve 25 provided in the pipe a is closed, and an inert gas such as nitrogen is supplied from the outside to make the system in an oxygen-free state.

  Further, the inside of the distillation system is decompressed to about 2 kPa to 10 kPa by a decompression device (not shown), and a heat source is supplied from the outside to the reboilers 19 a and 20 a, and the interior of the first distillation device 19 and the second distillation device 20 is, for example, 60 to 150. The temperature is raised to a temperature suitable for distillation at about ℃.

  Next, a thermal decomposition operation is started by operating the supply device 4 to supply molten polystyrene to the reaction tube 2. That is, waste polystyrene finely pulverized by a pulverizer (not shown) or the like is supplied to the hopper 21 by pneumatic transportation or a conveyor, and the waste polystyrene is supplied to a heating and melting part, where it is heated to about 200 to 250 ° C. to form molten polystyrene. The molten polystyrene is pushed out by the rotary screw 23 driven by the drive unit 24 and flows into the introduction part of the reaction tube 2 through the pipe a. In the case of expanded polystyrene, the volume is reduced with a solvent and then supplied to the supply device 4. The outer periphery of the pipe a is covered with a heat insulating layer.

  The molten polystyrene which has flowed into the reaction tube 2 is heated from the surroundings while passing through the inside thereof and gradually decomposes, and the pyrolysis gas generated from the discharge part flows out into the pipe b. The pyrolysis gas in the pipe b flows into the condenser 6 and is cooled there to condense high-boiling components such as styrene, styrene dimer and styrene trimer, and is discharged from the pipe c to the primary centrifuge 9 as oil. . On the other hand, low-boiling components such as toluene and ethylbenzene are discharged from the pipe d as low-boiling gas, and are supplied to the heating gas generator 5 as at least a part of gaseous fuel, for example.

  As shown in FIGS. 2 and 3, the condensed component flowing into the primary centrifuge 9 is separated into oil and solids in a bowl 30 rotating at about 1000 to 2000 rpm. The oil-rich effluent flowing out from the oil effluent part 38 by the separation operation is supplied to the first second centrifuge 10a via the pipe e, and the solid effluent flowing out from the solid part effluent part 39 of the primary centrifuge 9 is supplied. The minutely rich effluent is supplied to the first third centrifuge 11a (reference numeral 11 in FIG. 1) via the pipe f.

  That is, the control device 59 opens the automatic open / close valve 53 so as to supply the effluent to the first second centrifuge 10a and the first third centrifuge 11a, respectively. 54, 57, 60 are closed. The oil-rich effluent flowing out from the oil effluent portion 38 of the primary centrifuge 9 has a low viscosity that contains oil as a main component and contains a small amount of fine particles of undecomposed polystyrene and fine particles of impurity solids. The solid-rich effluent flowing out from the solid effluent portion 39 is a liquid mainly composed of fine particles of undecomposed polystyrene and fine particles of impurity solids, and a small amount of oil is attached to the effluent. It is a highly viscous gel.

  First, the operation of the second centrifuge 10 will be described. When the liquid level of the effluent in the first second centrifuge 10a is detected by the liquid level detection means 58 and the liquid level detection value reaches a preset value, the first level from the control device 59 is reached. A control signal is output to the second centrifuge 10a, and the automatic on-off valve 53 is closed to stop the supply of the effluent. Further, the drive motor is driven to start the separation operation of the first second centrifuge 10a. The separation operation is performed for a predetermined time at a high speed of about 2500 to 3000 rpm. In addition to the above control signals, a control signal is also output from the control device 59 to the second second centrifuge 10b, the automatic open / close valve 53 is opened, the automatic open / close valves 54, 57, 60 are closed, The effluent from the pipe e is supplied to the second second centrifuge 10b.

  When the separation operation of the first second centrifuge 10a is completed, a control signal is output from the control device 59 to the first second centrifuge 10a by the completion signal (for example, a timer setup signal), and the drive motor is turned on. The automatic stop valve 54 is stopped, and the pump 14 is operated. That is, the first second centrifuge 10 a moves to a discharge operation for discharging the separated oil from the pipe j to the oil storage tank 27.

  When the oil content of the first second centrifuge 10a is discharged, for example, a discharge completion signal is sent to the control device 59 from a liquid level detection means (not shown) provided near the bottom of the first second centrifuge 10a. As a result, a control signal is output from the control device 59, the automatic open / close valve 54 is closed, the pump 14 is stopped, and the oil discharge operation is completed.

  When the oil discharge operation in the first second centrifuge 10a is completed, a control signal is then output from the control device 59, the automatic open / close valve 57 is opened, and the cleaning liquid in the cleaning liquid tank 55 is pumped from the pipe r by the pump 56. It supplies to the inside of the 1st 2nd centrifuge 10a. The cleaning liquid flowing out from the inside circulates in the cleaning liquid tank 55 through the pipe s. When circulation of the cleaning liquid is continued for a predetermined time, the oil adhering to the inside of the first second centrifuge 10a (specifically, the stainless screen container or the inner wall surface of the casing 50) is dissolved and removed in the cleaning liquid. That is, most of organic substances such as styrene, pyrolysis by-products, undecomposed polystyrene, and other oil components are dissolved in styrene and removed.

  A control signal is output from the control device 59 when the oil is dissolved (for example, setup of a timer), the automatic open / close valve 57 is closed to finish the cleaning operation, and then the heating unit 51 is operated to perform an internal drying operation. Move. When the inside of the first second centrifuge 10a is heated to about 60 to 80 ° C. by the heating unit 51 and dried, the oil that has adhered to the inner wall evaporates, so that the solid is peeled off from the inner wall. When the drying progresses to some extent, the solid content naturally falls to the bottom due to its own weight.

  When the solid content dropped to the bottom accumulates to some extent, in response to a command from an operation unit (not shown) provided in the control device 59, a control signal is output to open the automatic open / close valve 60, and from the pipe i to the waste container 12a. Drain solids. On the other hand, the oil component adhering to the solid content due to drying and the oil component remaining inside are evaporated as described above, but the evaporated oil component is recovered in the condenser 6 through the pipe g. When the drying operation is completed, a control signal for stopping heating is output from the control device 59 to the heating unit 51. And it waits in preparation for the next switching after completion | finish of the supply of the said effluent to the 2nd 2nd centrifuge 10b.

  When the supply of the effluent to the second second centrifuge 10b is completed, that is, when the liquid level reaches a preset value, the control device is operated according to the procedure described for the first second centrifuge 10a. In accordance with a control signal from 59, the separation operation, oil discharge operation, washing operation and drying operation of the second second centrifuge 10b are sequentially performed. On the other hand, the operation of supplying the effluent to the first second centrifuge 10a is started again. In this way, the first second centrifuge 10a and the second second centrifuge 10b can be switched alternately to continuously separate the solid content. In the case where three or more second centrifuges 10 are provided, the solid content can be separated by sequentially switching them.

  In the above series of operations, when the degree of internal contamination by one separation operation in the second centrifuges 10a and 10b is relatively small, it is not necessary to perform the washing operation and the drying operation for each separation operation. It may be performed once for each separation operation. In terms of the certainty of the switching operation, the separation operation, the oil discharge operation, the washing operation and the drying operation in one second centrifuge 10 are the operations for supplying the effluent to the other second centrifuge 10. It is desirable to finish by the end. According to the experiment, it takes about 5 to 6 minutes to fill the effluent in the second centrifuge 10 to the operation compatible amount, but the separation operation is about 1 minute and the washing operation is 1.5 to 2 minutes. The degree of drying, solid content discharge operation is about 1.5 to 2 minutes, which sufficiently satisfies the above conditions.

  On the other hand, the cleaning liquid in the cleaning liquid tank 55 is gradually contaminated with impurities by repeating the above-described cleaning operation. When the cleaning liquid is contaminated, the cleaning power is also reduced, and thereby the separation performance of the second centrifuge 10 and the third centrifuge 11 is reduced. According to experiments, it has been found that such a decrease in separation capability can be determined from the flow rate of oil flowing through the pipe j or the pipe k.

  Therefore, in the present embodiment, the flow rate detecting means 61 is provided for each of the pipe j and the pipe k, and when the flow rate detection signal falls below a preset value, it is determined that the cleaning liquid is contaminated, and the signal is received. The control device 59 outputs a control signal to the cleaning liquid tank 55 to update the cleaning liquid. That is, the automatic open / close valve 62 provided in the pipe u is opened to discharge the contaminated cleaning liquid from the cleaning liquid tank 55, and the automatic open / close valve 63 provided in the pipe t is opened to replenish new cleaning liquid.

  Similarly to the solid content separation procedure in the second centrifuge 10, the solid content separation procedure in the third centrifuge 11 is also performed by alternately switching the two third centrifuges 11a and 11b. Although the operation, oil discharge operation, washing operation and drying operation can be performed, the description of the operation will be omitted because it overlaps with the case of the second centrifuge 10. Further, when three or more third centrifuges 11 are provided, the solid content can be separated by the same operation as that in the second centrifuge 10. The separation operation of the third centrifuge 11 is performed at a speed of about 3000 to 3500 revolutions / minute.

  The number of rotations of the bowl 30, the number of rotations of the screw conveyor 31, or the second centrifuge 10 and the third centrifuge at the time of the separation operation of the first centrifuge 9 constituting the solid-liquid separation device 8 described so far. The number of revolutions during the separation operation, the number of revolutions during the washing operation, the temperature range during the drying operation, and the like are desirably set in advance by experiments in consideration of the material composition to be put into these apparatuses.

  Next, the distillation operation will be described. In FIG. 1, the oil component supplied to the middle stage of the first distillation apparatus 19 is separated there by distillation, and low-boiling components such as toluene and ethylbenzene flow out from the top into the pipe m and are collected in a collection tank (not shown). The part is supplied to the heated gas generator 5 as fuel gas. On the other hand, high-boiling components such as styrene and a dimer or trimer of styrene flow out from the lower part to the pipe n and are supplied to the middle stage of the second distillation apparatus 20 by the pump 17.

  The high-boiling components supplied to the second distillation apparatus 20 are further separated there by distillation, and the low-boiling components made of styrene flow out from the top into the pipe o and are collected in a styrene collection tank (not shown). Part of the styrene stored in the styrene recovery tank is supplied to the cleaning liquid tank 55 as a cleaning liquid. Further, high-boiling components including styrene dimers and trimers flow out from the bottom into the pipe p, and are recovered by a pump 18 in a heavy oil recovery tank (not shown), and at least a part of the stored heavy oil is the heating gas generator. 5 is supplied as fuel oil.

  In the above embodiment, the solid-liquid separator 8 is constituted by the first centrifuge 9, the second centrifuge 10 and the third centrifuge 11, but the processing apparatus of the present invention is not necessarily limited to this configuration. Is not to be done. For example, even if the oil obtained by separating the solid content from the condensed component in the first centrifuge 9 is circulated through the downstream piping and equipment for a considerably long period of time, the solid content is such that it does not adversely affect them. If it is content, there is little necessity to provide the 2nd centrifuge 10.

  Further, when the content of oil contained in the solid-rich effluent flowing out from the first centrifuge 9 is extremely small, the effluent is directly disposed in the waste container 13 without providing the third centrifuge 11. Can also be discharged.

  When the pyrolyzer 1 that has been operated continuously for a long time is stopped, if solids are attached to the inside of the equipment downstream of the condenser 6, remove them before the solids are firmly fixed. It is desirable. The objects to be removed are the insides of the first centrifuge 9, the second centrifuge 10, the third centrifuge 11, the waste containers 12, 13 and the like, which are removed after being dried and easily peeled off. . In addition, what is necessary is just to perform the same operation as said drying and removal operation about the 2nd centrifuge 10 and the 3rd centrifuge 11. FIG.

  The waste polystyrene was thermally decomposed by the process flow of FIG. 1 and the generated pyrolysis gas was treated. Polystyrene paper (PSP) waste as a raw material was processed to a particle size of 0.3 to 0.5 cm in diameter and supplied to the hopper 21 of the supply device 4. The molten polystyrene obtained by the supply device 4 was continuously supplied to the reaction tube 2 of the pyrolyzer 1 at a rate of 150 kg / hour, and pyrolysis was performed at a pyrolysis temperature of about 700 ° C. for 100 hours.

  Polystyrene paper contains about 1% of talc, which is an inorganic substance, as a molding nucleating agent. Therefore, the rotation speed of the bowl 30 during the separation operation of the first centrifugal separator 9 that separates the solid content from the condensed component flowing out from the condenser 6 is set to 2000 rpm, and the rotation speed of the screw conveyor 31 is set to a slightly different rotation speed. Of the centrifuge 10 (10a, 10b) is set to 3000 rpm, the washing speed is set to 100 rpm, the drying temperature is set to 80 ° C., and the third centrifuge 11 (11a, 11b) is separated. The number of revolutions at the time was set to 3500 rpm, the number of revolutions at the time of washing was set to 100 rpm, and the drying temperature was set to 80 ° C., and solid content separation operation and the like were performed.

  During the operation period of 100 hours, the oil component flowing out from the solid-liquid separator 8 to the oil component recovery tank 27 contains substantially no solid content, and the distillation operation by the first distillation device 19 and the second distillation device 20 is performed. The efficiency did not decrease. In addition, each centrifuge constituting the solid-liquid separator 8 could be continuously operated without interruption. Note that the yield and purity of styrene near the end of the 100-hour operation period maintained the level of yield and purity in the case of good maintenance in the conventional apparatus.

  After 100 hours of continuous operation, the waste containers 12a, 12b, 13a, and 13b in which the solid content was discharged after the system temperature of the solid-liquid separator 8 was cooled to room temperature were examined. Solid contents in a dry state were deposited at a ratio of 0.020%, 0.022%, 0.610%, and 0.588%, respectively, and the total was 1.240%. In addition, it is recognized that dirt substances adhere to the inside of the condenser 6, the first centrifuge 9, the second centrifuges 10a and 10b, the third centrifuges 11a and 11b, and the piping within the observable range. I couldn't.

  The pyrolysis gas treatment method and treatment apparatus of the present invention can be used for separating and removing fine solids contained in pyrolysis gas obtained by pyrolysis of polystyrene.

The process flow figure of the processing apparatus of the pyrolysis gas which concerns on this invention. FIG. 3 is a cross-sectional view showing an example of the first centrifuge 9. The process flow figure which shows the peripheral part of the 2nd centrifuge 10 concretely.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal decomposer 2 Reaction tube 3 Heating part 4 Supply part 5 Heated gas generator 6 Condenser 7 Depressurizer 8 Solid-liquid separator 9 First centrifuge 10, 10a, 10b Second centrifuge

11, 11a, 11b Third centrifuge 12, 12a, 12b, 13, 13a, 13b Waste container 14-18 Pump 19 First distillation device 19a Reboiler 20 Second distillation device 20a Reboiler

DESCRIPTION OF SYMBOLS 21 Hopper 22 Extrusion part 23 Rotating screw 24 Drive part 25 On-off valve 26 Burner 27 Oil content storage tank 30 Bowl

31 screw conveyor 32 shaft 33 driving pulley 34 shaft 35 introduction pipe 36 driving pulley 37 spiral blade 38 oil content outflow portion 39 solid content outflow portion 50 casing

DESCRIPTION OF SYMBOLS 51 Heating part 53,54 Automatic on-off valve 55 Cleaning liquid tank 56 Pump 57 Automatic on-off valve 58 Liquid level detection means 59 Control apparatus 60 Automatic on-off valve 61 Flow rate detection means 62,63 Automatic on-off valve au piping D1, D2 Duct

Claims (11)

  In the method of treating a pyrolysis gas containing fine solids obtained in the pyrolyzer 1 for pyrolyzing plastic, the pyrolysis gas is supplied to the condenser 6 to condense the high-boiling components, and the condenser 6 A method for treating a pyrolysis gas, characterized in that a condensed component flowing out of the gas is supplied to a solid-liquid separation device 8 to separate a solid component to obtain an oil component.   The method for treating pyrolysis gas according to claim 1, wherein a first centrifuge 9 is used as the solid-liquid separator 8. In claim 2, in addition to the first centrifuge 9 as the solid-liquid separator 8, at least one of the second centrifuge 10 and the third centrifuge 11 is used.
Supplying the condensed component to the first centrifuge 9, where the solids are separated from the condensed component;
When the second centrifuge 10 is used, the effluent from the oil spill part 38 of the first centrifuge 9 is supplied to the second centrifuge 10 where the effluent is separated into oil and solids,
When the third centrifuge 11 is used, the effluent from the solid content outflow portion 39 of the first centrifuge 9 is supplied to the third centrifuge 11 where the effluent is separated into oil and solids. By
A method for treating pyrolysis gas, characterized by obtaining oil.   In claim 3, when the second centrifuge 10 is used, two or more second centrifuges 10 are used, and the effluent from the oil outflow portion 38 of the first centrifuge 9 is supplied to each second centrifuge 9. When the third centrifuge 11 is used by sequentially supplying the centrifuges (10a, 10b) to separate the effluent into oil and solids and using the third centrifuge 11, two or more third centrifuges 11 are provided. The effluent from the solids outflow part 39 of the first centrifuge 9 is sequentially supplied to the third centrifuges (11a, 11b) to separate the effluent from oil and solids, respectively. A method for treating pyrolysis gas.   In Claim 4, while each said 2nd centrifuge (10a, 10b) or each 3rd centrifuge (11a, 11b) is not performing separation operation, the inside is wash | cleaned with a washing | cleaning liquid, Then, it dries. A method for treating a pyrolysis gas, characterized in that residual oil that evaporates by drying is collected in the condenser 6.   5. The thermal decomposition according to claim 1, wherein when the operation of the pyrolyzer 1 is stopped, the solid content adhering to the inside of the solid-liquid separator 8 is removed by a drying operation. Gas processing method.   In an apparatus for processing a pyrolysis gas containing fine solids obtained by a pyrolyzer 1 that pyrolyzes plastic, a condenser 6 that condenses the pyrolysis gas and a condensed component obtained by the condenser 6 An apparatus for treating pyrolysis gas, comprising a solid-liquid separation device 8 for separating oil from solids to obtain oil.   8. The pyrolysis gas treatment apparatus according to claim 7, wherein the solid-liquid separation device 8 is constituted by a first centrifuge 9. The supply side of the first centrifuge 9 according to claim 8, wherein the solid-liquid separator 8 is constituted by the first centrifuge 9 and at least one of the second centrifuge 10 and the third centrifuge 11. Is connected to the condensate discharge side of the condenser 6,
When installing the second centrifuge 10, connect the supply side of the second centrifuge 10 to the oil outflow portion 38 of the first centrifuge 9,
When installing the 3rd centrifuge 11, the processing side of the pyrolysis gas characterized by connecting the supply side of the 3rd centrifuge 11 to the solid content outflow part 39 of the 1st centrifuge 9. In Claim 9, when installing the said 2nd centrifuge 10, two or more 2nd centrifuges 10 are installed, the liquid level detection means 58 is provided in each, and each 2nd centrifuge ( 10a, 10b) is connected to the oil component outflow portion 38 of the first centrifuge 9 via the automatic opening / closing valve 53, and the liquid level detection provided in any of the second centrifuges (10a, 10b). When the liquid level detection signal of the means 58 reaches a preset value, control is performed so that the automatic opening / closing valve 53 provided in the second centrifuge (10a, 10b) is closed and the separation operation is performed. A device 59 is provided;
In the case where the third centrifuge 11 is provided, two or more third centrifuges 11 are installed, and the liquid level detecting means 58 is provided for each of them, and the supply of each third centrifuge (11a, 11b). The liquid level of the liquid level detection means 58 provided on any of the third centrifuges (11a, 11b) is connected to the solid content outflow part 39 of the first centrifuge 9 via the automatic opening / closing valve 53, respectively. When the detection signal reaches a preset value, a control device 59 is provided for controlling to perform the separation operation by closing the on-off valve 53 provided in the third centrifuge (11a, 11b). An apparatus for treating pyrolysis gas characterized by the following. In Claim 9, the washing | cleaning means and drying means which wash | clean the inside of each said 2nd centrifuge 10 or each 3rd centrifuge 11 are provided, and each said 2nd centrifuge (10a, 10b) or each 3rd centrifuge. An apparatus for treating pyrolysis gas, characterized in that, when the separation operation of the centrifuge (11a, 11b) is completed, the inside thereof can be cleaned and dried.

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