Thermal decomposition device

Abstract

Provided is a thermal decomposition device that can more reliably separate gas in either a thermal decomposition section or a residue discharge section that discharges residue from the thermal decomposition section, thereby reducing the amount of gas coexisting with the residue in the downstream of the residue discharge section. [Solution] The pyrolysis device 1 includes a pyrolysis section 20 that receives and pyrolyzes raw resin, a pyrolysis gas separation section A that separates pyrolysis gas generated by pyrolysis in the pyrolysis section 20, a gas treatment section 100 that processes the pyrolysis gas sent through the pyrolysis gas separation section A, and a residue discharge section 30 that discharges undecomposed residue generated in the pyrolysis section 20. The residue discharge section 30 includes a gear pump (positive displacement pump) 60 that sucks in and discharges undecomposed residue from an outlet section 23f of the pyrolysis section 20.

Description

[Technical field]

[0001] The present disclosure relates to an apparatus for pyrolysis of resins. [Background technology]

[0002] In recent years, with the rise in resource prices and growing awareness of environmental issues, there has been a growing trend to collect and recycle resin molded products such as poly(meth)acrylic esters. As an example, a method is known in which a monomer obtained by thermally decomposing (depolymerizing) poly(meth)acrylic esters is collected and used to manufacture a new molded product. This type of resin recycling method is also called chemical recycling.

[0003] In chemical recycling, the resin is pyrolyzed by heating the resin at a temperature of, for example, about 300°C to 500°C. For example, in the regeneration system described in Patent Document 1, pyrolysis gas generated in the pyrolysis section is extracted through a gas extraction section (vent). The pyrolysis gas is purified or cooled in a gas treatment device. Alternatively, impurities in the pyrolysis gas are adsorbed and removed in the gas treatment device. A residue discharge section is provided near the downstream end of the pyrolysis section for discharging the residue generated in the pyrolysis section and including undecomposed components. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2024-48830 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional system described above, the residue is discharged by a residue discharge section and is contained and stored in a storage tank through a connecting pipe. The storage tank is provided with a gas discharge section. Furthermore, in consideration of the flammability or combustibility of the gas present in the storage tank, safety measures are taken, such as cooling the residue in the storage tank or supplying an inert gas into the storage tank. Thus, the more gas that may be generated or present in the residue storage device (or residue storage section), the more stringent safety measures are required.

[0006] The present disclosure describes a thermal decomposition device that can more reliably separate gas either in the thermal decomposition section or in the residue discharge section that discharges the residue from the thermal decomposition section, thereby reducing the amount of gas coexisting with the residue in the downstream of the residue discharge section. [Means for solving the problem]

[0007] The present disclosure provides several aspects, including: [1] A pyrolysis section that receives and pyrolyzes raw resin; a pyrolysis gas separation section for separating a pyrolysis gas generated by pyrolysis in the pyrolysis section; a gas processing unit for processing the pyrolysis gas sent through the pyrolysis gas separation unit; A residue discharge section connected to an outlet of the pyrolysis section and discharging undecomposed residue generated in the pyrolysis section, The residue discharge section of the pyrolysis apparatus includes a positive displacement pump that sucks in and discharges the undecomposed residue from the outlet section.

[0008] According to the pyrolysis device of [1], by providing a positive displacement pump in the residue discharge section, even if gas is mixed with the undecomposed residue discharged from the outlet of the pyrolysis section, the gas is sealed by the internal structure of the positive displacement pump and is unlikely to leak out to the discharge side of the positive displacement pump. This sealing effect allows gas to be separated more reliably in the pyrolysis section or residue discharge section. In addition, the amount of gas coexisting with the residue can be reduced in the downstream of the residue discharge section (i.e., the residue storage section or granulation device connected to the discharge section of the positive displacement pump).

[0009] [2] The pyrolysis device according to [1], wherein the residue discharge unit further includes a flow path switching unit connected to the discharge unit of the positive displacement pump and switching the flow path of the undecomposed residue discharged by the positive displacement pump. With this configuration, even if a high pressure state (such as a blockage) occurs downstream of the positive displacement pump, the flow path can be switched to discharge the undecomposed residue.

[0010] [3] The pyrolysis device according to [1] or [2], wherein the residue discharge section is provided between the outlet section of the pyrolysis section and the suction section of the positive displacement pump, and further includes a chamber having an internal space of a certain volume or more and a gas outlet. According to this configuration, gas can be taken out from the gas outlet in the chamber as well. In addition, a certain amount of undecomposed residue can be stored in the chamber, so that the positive displacement pump can be operated with a margin. Since the chamber functions as a volumetric buffer, the temperature of the undecomposed residue can be lowered in the chamber, and more general specifications can be applied to the discharge side of the positive displacement pump (i.e., special specifications can be avoided).

[0011] [4] The pyrolysis device according to [3], wherein the residue discharge section further includes another positive displacement pump provided between the outlet section of the pyrolysis section and the chamber. According to this configuration, since a plurality of positive displacement pumps are provided (in two stages), the above-mentioned gas sealing effect is further enhanced.

[0012] [5] A pressure gauge is provided at or near the outlet of the pyrolysis section; The pyrolysis device according to any one of [1] to [4], wherein the positive displacement pump operates and stops in response to the pressure value detected by the pressure gauge. According to this configuration, the positive displacement pump operates (by controlling the number of reciprocating motions or the number of rotations) and stops in response to the pressure value, so that the undecomposed residue can be discharged reliably, and the inside of the system can be sealed by leaving a certain amount of residue in the pyrolysis section. It is possible to prevent the pressure from increasing too much, and to prevent blockage due to the undecomposed residue. Furthermore, it is possible to prevent the leakage of flammable gas to the outside of the system and the intrusion of oxygen gas from the outside of the system.

[0013] [6] The pyrolysis device according to any one of [1] to [5], wherein the positive displacement pump is operated intermittently or so as to vary the number of rotations or the number of reciprocating movements of the movable part. With this configuration, it is possible to suppress fluctuations in the amount of undecomposed residue inside the pyrolysis section.

[0014] [7] The pyrolysis apparatus according to any one of [1] to [6], wherein the positive displacement pump is a gear pump. A gear pump transports a fluid by meshing multiple gears that are rotating parts, and therefore has excellent gas sealing ability among positive displacement pumps. Effect of the Invention

[0015] According to the present disclosure, the sealing effect of the positive displacement pump allows gas to be separated more reliably in the pyrolysis section or the residue discharge section. Also, the amount of gas coexisting with the residue in the downstream of the residue discharge section can be reduced. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a flow diagram of a pyrolysis apparatus according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing a first configuration example of the residue discharge unit and its periphery. [Diagram 3] FIG. 3 is a diagram showing a second configuration example of the residue discharge unit and its periphery. [Figure 4] FIG. 4 is a diagram showing a third configuration example of the residue discharge unit and its periphery. [Diagram 5] FIG. 5 is a diagram showing a fourth configuration example of the residue discharge unit and its periphery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions will be omitted. Each drawing is created for the purpose of explanation, and is drawn to particularly emphasize the target portion of the explanation. Therefore, the dimensional ratio of each member in the drawings does not necessarily match the actual one.

[0018] The resin pyrolysis device 1 according to an embodiment of the present disclosure is a device that obtains monomers by pyrolyzing (depolymerizing) used resin molded bodies (e.g., products collected from the market, etc.) or discarded resin molded bodies (e.g., factory waste, etc.). Not limited to resins originating from factories, post-consumer recycled plastics (PCR) can also be treated by the pyrolysis device 1. The monomers obtained by the pyrolysis device 1 are repolymerized by another device to obtain polymers (or recycled monomers) again. The monomers obtained by pyrolysis, i.e., pyrolyzed monomers, may contain several types of impurities. The pyrolysis device 1 of this embodiment and another repolymerization device enable chemical recycling of any resin. In this specification, "used or discarded resin" may be called "raw material" or "raw material resin".

[0019] The type of resin to be recovered by the pyrolysis device 1 is not particularly limited. The pyrolysis device 1 may pyrolyze (meth)acrylic resins, styrene resins, polycarbonate, or polyethylene terephthalate. For example, when polymethyl methacrylate (PMMA) as one of the resins is pyrolyzed, methyl methacrylate (MMA) which is a monomer is obtained. At this time, some low-boiling point impurities are contained. For example, the impurities may be methyl propionate, methyl isobutyrate, methyl acrylate, ethyl acrylate, butyl acrylate, methanol, etc. It is considered that the influence of the raw material origin is large for methyl acrylate.

[0020] Even when recycling one type of resin, there are various types of impurities. In some cases, typical impurities such as those described above are included, and in other cases, special impurities are included. The impurities may be low-boiling point impurities or high-boiling point impurities. Low-boiling point impurities are substances that have a lower boiling point than the monomers of the resin to be recovered (i.e., the resin to be recycled). High-boiling point impurities are substances that have a higher boiling point than the monomers of the resin to be recovered (i.e., the resin to be recycled). The pyrolysis device 1 can handle any type of impurity.

[0021] The type and amount of impurities that can be tolerated in the pyrolysis monomer may vary (may be set appropriately) depending on the type of resin, or may vary (may be set appropriately) for the same resin depending on the intended use after recycling. When the use form of the recycled resin differs, it is often the case that the required level of impurity concentration in the recycled resin differs. The pyrolysis device 1 of this embodiment is applicable to all impurities and all concentration levels (the above-mentioned required level).

[0022] The configuration of the pyrolysis device 1 will be described with reference to Fig. 1. As shown in Fig. 1, the pyrolysis device 1 includes a pretreatment section 10, a pyrolysis section 20, a pyrolysis gas separation section A, and a gas treatment section 100. Although valves, instruments, detailed piping configurations, and the like are omitted in Fig. 1, each section of the pyrolysis device 1 may have a known detailed configuration for realizing the function of each section described later.

[0023] The pretreatment section 10 pretreats the raw resin before it is supplied to the pyrolysis section 20. Examples of pretreatment include conventionally known processes such as a fine powder removal process, a metal removal process, and a process for separating or sorting different resins. The pretreatment section 10 has a pretreatment device 11 that performs pretreatment such as fine powder removal, and a first feeder 12 that supplies the pretreated raw material to the pretreatment section 10. The type of the first feeder 12 is not particularly limited and can be selected from known devices.

[0024] The pyrolysis section 20 performs pyrolysis of the raw material supplied from the pretreatment section 10. In other words, the pyrolysis section 20 receives and pyrolyzes the raw material resin. The pyrolysis section 20 has, for example, a resin receiving section 21, a second feeder 22, and a pyrolysis gasification device 23. The resin receiving section 21 can also be said to be a resin inlet into which the resin is input. The resin receiving section 21 is a raw material supply section that supplies raw material to the pyrolysis gasification device 23. The type of the second feeder 22 is not particularly limited and can be selected from known devices. Any of the pretreatment section 10, the resin receiving section 21, and the second feeder 22 may be provided with a device for processing the raw material, such as crushing, a detector for detecting foreign matter contained in the raw material, or a meter for controlling the input amount of the raw material.

[0025] The pyrolysis gasification apparatus 23 performs pyrolysis of the raw material resin to obtain a gaseous pyrolysis product (hereinafter also referred to as pyrolysis gas). For example, an extrusion type device or a fluidized bed type device may be used as the pyrolysis gasification apparatus 23. A kneader may be used as the pyrolysis gasification apparatus 23. Any known (arbitrary and suitable) device capable of pyrolyzing the target raw material resin may be used as the pyrolysis gasification apparatus 23.

[0026] Suitable examples of the pyrolysis gasification device 23 include twin-screw extruders such as a twin-screw co-rotating extruder and a twin-screw counter-rotating extruder. These extruders are equipped with a raw material inlet, a cylinder, and a screw 23a (see FIG. 2, etc.) disposed inside the cylinder, and are devices capable of transporting the raw material input from the inlet in a predetermined direction while heating it.

[0027] An example of the pyrolysis gasification apparatus 23 being a kneader is the apparatus described in U.S. Patent No. 10,301,235. An example of the pyrolysis gasification apparatus 23 being a fluidized bed heater is the apparatus described in Japanese Patent Laid-Open No. 2009-112902.

[0028] The temperature at which the poly(meth)acrylic acid ester is thermally decomposed in the thermal decomposition section 20 may be selected from the range of, for example, 300°C to 500°C, 400°C to 500°C, or 450°C to 500°C.

[0029] A residue storage section 70 is connected to the pyrolysis section 20 (specifically, to the pyrolysis gasification apparatus 23) via a residue discharge section 30, which will be described later, and the like. The residue storage section 70 stores the residue (undecomposed residue) discharged from the pyrolysis gasification apparatus 23 by the residue discharge section 30. The method of storing the residue is not particularly limited and can be selected from known methods. The residue storage section 70 may include a processing device or the like that processes the residue into a disposable state. In addition to or instead of the residue storage section 70, a granulation device or the like that granulates the undecomposed residue may be provided.

[0030] 2, the pyrolysis gas separation section A includes, for example, a pyrolysis gas outlet pipe L1 provided at an upper part near the outlet 23f of the pyrolysis gasification apparatus 23. The pyrolysis gas outlet pipe L1 extends, for example, upward from the pyrolysis gasification apparatus 23 and outputs the pyrolysis gas generated by pyrolysis in the pyrolysis gasification apparatus 23. That is, the pyrolysis gas separation section A separates the pyrolysis gas generated by pyrolysis in the pyrolysis section 20. The internal structure of the pyrolysis gasification apparatus 23 is capable of separating the pyrolysis gas and the undecomposed residue generated in the pyrolysis gasification apparatus 23.

[0031] As shown in Fig. 1, the gas processing section 100 processes the pyrolysis gas sent through the pyrolysis gas separation section A. The gas processing section 100 has, for example, a condensation section 40 and a purification section 50. In Fig. 1, the downstream end of the pyrolysis gas discharge pipe L1 is connected to, for example, the condensation section 40.

[0032] A partial condenser may be provided between the thermal decomposition section 20 and the condensation section 40. The partial condenser, for example, condenses (liquefies) and removes high-boiling-point impurities contained in the gaseous thermal decomposition product obtained in the thermal decomposition section 20. By disposing the partial condenser downstream of the thermal decomposition section 20, the load of the purification process in the purification section can be further reduced. The removal of high-boiling-point impurities by the partial condenser is performed, for example, at a temperature that is equal to or higher than the boiling point and lower than the ignition point of the substance contained in the thermal decomposition product as a recovery target, and lower than the boiling point and higher than the melting point of the high-boiling-point impurities. That is, the high-boiling-point impurities are removed while the thermal decomposition product as a whole remains in a gaseous state.

[0033] The condensation section 40 liquefies the pyrolysis gas discharged from the pyrolysis section 20. The condensation section 40 includes a cooling section. The condensation section 40 cools and liquefies the pyrolysis gas obtained in the pyrolysis section 20 to obtain a condensed liquid.

[0034] The temperature at which the pyrolysis gas is cooled is preferably lower than the boiling point of the substance to be recovered. For example, when the pyrolysis gas contains methyl methacrylate or methyl acrylate to be recovered, the pyrolysis gas is cooled at a temperature lower than 101°C, which is the boiling point of methyl methacrylate, or lower than 80°C, which is the boiling point of methyl acrylate. The configuration of the condensation section 40 is not particularly limited, and a known device such as a condenser can be used.

[0035] The liquid pyrolysate (condensate) that has passed through the condensation section 40 is supplied to the downstream purification section 50. A storage section (not shown) for storing the condensate may be provided between the condensation section 40 and the purification section 50. A dehydration section may be provided at any location within the storage section.

[0036] The purification section 50 has a plurality of purification columns (a first purification column 51 and a second purification column 52) and a cooling mechanism 53. FIG. 1 is a diagram showing an embodiment in which low boiling point impurities are removed in the first purification column 51 and high boiling point impurities are removed in the second purification column 52. The purification section 50 purifies the condensate. Each of the first purification column 51 and the second purification column 52 purifies the liquid pyrolysate (condensate) obtained in the condensation section 40. In this specification, "purification of the pyrolysate" means increasing the proportion of the components to be recovered among the components contained in the pyrolysate.

[0037] In the first purification column 51, low boiling point impurities are removed from the liquid pyrolysate (condensate) obtained in the condensation section 40. Specifically, by purifying the pyrolysate in the first purification column 51, a gas mainly containing low boiling point impurities is discharged from the top of the first purification column 51, and a liquid containing a large amount of the component to be recovered is sent from the bottom of the first purification column 51 to the second purification column 52. The gas mainly containing low boiling point impurities discharged from the top of the first purification column 51 is cooled and liquefied by the cooling mechanism 53. From the viewpoint of purification efficiency, it is preferable to discard a part of the cooled liquid (downward arrow in FIG. 1) and return the remainder to the first purification column 51.

[0038] In the second purification tower 52, high boiling point impurities are removed from the liquid sent from the bottom of the first purification tower 51. Specifically, the liquid sent from the bottom of the first purification tower 51 is purified in the second purification tower 52, so that a gas mainly containing the components to be recovered is discharged from the top of the second purification tower 52, and a liquid containing high boiling point impurities accumulates at the bottom of the second purification tower 52. The liquid accumulated at the bottom of the second purification tower 52 can be discarded by a known method. For example, the liquid accumulated at the bottom of the second purification tower 52 may be discarded after being stored in a waste liquid tank 57. The gas containing a large amount of the components to be recovered that is discharged from the top of the second purification tower 52 is cooled and liquefied by a cooling mechanism 53, and is sent to a filling section (not shown) as a product.

[0039] 1 shows a configuration in which low boiling point impurities are removed in the first purification column 51 and high boiling point impurities are removed in the second purification column 52, but the configuration of the purification section 50 is not limited to this example. It is possible to adopt a configuration in which high boiling point impurities are removed in the first purification column 51 and low boiling point impurities are removed in the second purification column 52. In that case, an appropriate device configuration may be adopted so that a liquid containing a large amount of the component to be recovered is stored in the packed section.

[0040] The liquid pyrolysate introduced into the purification section 50 (first purification column 51 and second purification column 52) may or may not contain water. When the liquid pyrolysate introduced into the purification section 50 contains water, the water may or may not be removed in the purification section 50. The configuration of the purification section 50 is not particularly limited, and a known purification device such as a purification column can be applied.

[0041] The cooling mechanism 53 cools and liquefies the gas discharged from the first purification column 51 and the second purification column 52. The temperature at which the gas is cooled may be set appropriately depending on the gas discharged from the first purification column 51 and the second purification column 52, but is preferably a temperature lower than the boiling point of the main components contained therein. The configuration of the cooling mechanism 53 is not particularly limited, and known devices such as condensers (for example, double-tube type, shell-and-tube type, plate type, spiral type, etc.) can be applied. As described above, the purified monomer storage tank 57 is a tank for storing and disposing of monomers containing a large amount of high-boiling-point impurities.

[0042] The above-mentioned configuration is an example of the gas processing unit 100. The gas processing unit 100 may have a different configuration for processing the pyrolysis gas. Only the condensation unit 40 may be provided and the purification unit 50 may be omitted, or only the purification unit 50 may be provided and the condensation unit 40 may be omitted. The liquid pyrolysis product that has passed through the condensation unit 40 may be filled in a filling unit (not shown). The filling unit may include a storage container such as a tank and a filling container such as a drum. The pyrolysis product may be shipped as necessary after being filled in a drum or the like. In addition to the above, the gas processing unit may include a collection process for collecting droplets, an impurity removal process by contact with an adsorbent, an ion removal process by an ion exchange unit, and a dehydration process by a dehydration unit. At least one of these processes may be appropriately combined, or the gas processing unit may have all of these processes.

[0043] As shown in FIG. 1 and FIG. 2, the pyrolysis device 1 further includes a residue discharge section 30 connected to the outlet section 23f of the pyrolysis gasification device 23. The residue discharge section 30 is provided between the pyrolysis gasification device 23 and the residue storage section 70, and discharges the undecomposed residue generated in the pyrolysis section 20. Here, the "undecomposed residue" means a component generated by pyrolysis of methyl (meth)acrylate and the like, other than the pyrolysis gas. The undecomposed residue is generally a liquid substance. Examples of the undecomposed residue include decomposed or undecomposed components other than polymethyl (meth)acrylate contained in the raw resin, such as polymethyl (meth)acrylate that was not gasified by pyrolysis, colorants, diffusing agents, and inorganic fillers, undecomposed different resins, or pyrolyzed, refractory copolymer components.

[0044] As shown in FIG. 2, the residue discharge section 30 has a gear pump (positive displacement pump) 60 connected directly or indirectly to the outlet 23f of the pyrolysis gasification apparatus 23. An appropriate connection section 25 may be provided between the gear pump 60 and the outlet 23f. The connection section 25 is an adapter for connecting the pyrolysis gasification apparatus 23 and the gear pump 60. For example, inside the cylindrical connection section 25, a flow path 25a is formed to guide the undecomposed residue discharged from the outlet 23f of the pyrolysis gasification apparatus 23 to a downstream device such as the gear pump 60. The shape and size of the flow path 25a are appropriately determined so as to fit both the outlet 23f and the suction section 61 of the gear pump 60. An external heater may also be provided in the connection section 25. A static mixer may be provided inside the connection section 25 to induce a flow of a fluid. Furthermore, a breaker plate may be provided inside the connection section 25 to protect the gear pump 60. Note that "(two parts) are indirectly connected" means that another member is interposed between the two parts. The connecting part 25 may be omitted, and the suction part 61 of the gear pump 60 may be directly connected to the outlet part 23f. The outlet part 23f of the pyrolysis gasification apparatus 23 and the gear pump 60 are connected so that a fluid can move (flow) between them.

[0045] The gear pump 60 includes a motor (not shown), and sucks in and discharges undecomposed residue from the outlet 23f of the pyrolysis gasification apparatus 23 by the driving force of the motor. The gear pump 60 includes a suction section 61 directly or indirectly connected to the outlet 23f of the pyrolysis gasification apparatus 23, a first gear 64A and a second gear 64B that rotate by the driving force of the motor, and a discharge section 62 provided on the opposite side of the suction section 61. The gear pump 60 is, for example, an external gear pump. The suction section 61 and the discharge section 62 are integrally formed at one end and the other end of the casing 63, respectively, and have a shape that can be connected to the connection section 25 or other piping material. The residue discharge section 30 further includes a residue discharge pipe 39 connected to the discharge section 62. The residue discharge pipe 39 connects the discharge section 62 of the gear pump 60 to the above-mentioned residue storage section 70.

[0046] The first gear 64A and the second gear 64B are housed in a casing 63 and rotate in a state of meshing with each other. A fluid is sucked from the suction section 61 side into a clearance (gap) having a predetermined volume between the first gear 64A and the second gear 64B and the inner wall surface of the casing 63, and is discharged to the discharge section 62 side with the rotation of the first gear 64A and the second gear 64B. The gear pump 60, which is a positive displacement pump, enables a quantitative liquid transfer according to the rotation speed of the first gear 64A and the second gear 64B. The gear pump 60 has specifications that can withstand at least a predetermined high temperature condition and a predetermined pressure, and has a sealing property against pyrolysis gas. As the gear pump 60, a known pump that can be applied to the undecomposed residue generated in the pyrolysis gasification device 23 may be adopted.

[0047] A thermometer 27 for measuring the temperature inside the pyrolysis gasification apparatus 23 and a pressure gauge 28 for measuring the pressure inside the pyrolysis gasification apparatus 23 are provided at appropriate positions near the outlet 23f of the pyrolysis gasification apparatus 23. The pyrolysis apparatus 1 may include a controller (not shown) that receives measured values ​​output from the thermometer 27 and the pressure gauge 28 and controls the operation of the gear pump 60. The controller may be provided outside the residue discharge section 30, or may be provided attached to the gear pump 60 as a part of the residue discharge section 30. The controller inputs information about the temperature measured by the thermometer 27 (temperature value) and information about the pressure measured by the pressure gauge 28 (pressure value). The controller controls the motor of the gear pump 60 based on the received temperature value and pressure value, and operates or stops (turns on and off) the gear pump 60. The controller also controls the rotation speed of the motor of the gear pump 60 based on the received temperature value and pressure value. Note that the temperature value may not be used in the control of the controller, and only the pressure value may be used.

[0048] The thermometer 27 and the pressure gauge 28 may be provided at the outlet portion 23f, not in the vicinity of the outlet portion 23f, or may be provided near the connection portion 25 or the suction portion 61 of the gear pump 60.

[0049] In the pyrolysis device 1, the pyrolysis gasification device 23 is operated continuously. On the other hand, the gear pump 60 is operated intermittently or continuously while controlling the rotation speed (rotation speed of the movable part). In other words, the rotary type positive displacement pump is operated intermittently or so that the rotation speed of the movable part is variable. The purification section 50 is controlled, for example, by the controller and operates and stops according to at least the pressure value detected by the pressure gauge 28. The term "operation" includes both control to keep the rotation speed of the motor constant and control to make the rotation speed of the motor variable. Therefore, the controller stores a pressure threshold value as an operating condition (and a stop condition) of the gear pump 60. When the controller controls the gear pump 60 using a temperature value in addition to the pressure value, the temperature value may be added to the operating condition of the gear pump 60. By operating the device while controlling the rotation speed of the gear pump 60 so that the value of the pressure gauge is constant (or approximately constant), the amount of undecomposed residue inside the pyrolysis section 20 can be kept constant (or approximately constant).

[0050] In the pyrolysis apparatus 1 described above, the raw material resin is sequentially pyrolyzed in the pyrolysis gasifier 23. In the pyrolysis gasifier 23, pyrolysis gas and undecomposed residue are generated. The pyrolysis gas is discharged from the pyrolysis gasifier 23 through the pyrolysis gas discharge pipe L1 and sent to the condensation section 40. When the pressure near the outlet 23f (or the outlet 23f) in the pyrolysis gasifier 23 is equal to or higher than a predetermined pressure threshold, the gear pump 60 is operated or the rotation speed is increased to discharge the undecomposed residue from the outlet 23f, and the undecomposed residue is sucked in and discharged by the gear pump 60. When the pressure near the outlet 23f (or the outlet 23f) in the pyrolysis gasifier 23 is lower than a predetermined pressure threshold, the gear pump 60 is stopped or the rotation speed is reduced to accumulate the undecomposed residue near the outlet 23f or in the space between the outlet 23f and the suction section 61. In this manner, by operating the gear pump 60 on and off or controlling the rotation speed of the gear pump 60, the undecomposed residue is reliably discharged and a certain amount of residue is accumulated in the thermal decomposition section.

[0051] In the pyrolysis device 1, the undecomposed residue discharged from the outlet 23f of the pyrolysis section 20 may contain gas. By providing the gear pump 60, which is a positive displacement pump, in the residue discharge section 30, even if the undecomposed residue discharged from the outlet 23f contains gas, the gas is sealed by the internal structure of the gear pump 60, and is less likely to leak to the discharge section 62 side (discharge side) of the gear pump 60. Due to this sealing effect, the gas mixed with the undecomposed residue is discharged to the pyrolysis gas discharge pipe L1, and the gas can be separated more reliably in the pyrolysis section 20 or the residue discharge section 30. In addition, the amount of gas coexisting with the residue can be reduced in the rear stage of the residue discharge section 30 (i.e., the residue storage section 70 connected to the end of the discharge section 62 of the gear pump 60, etc.).

[0052] The effect of the residue discharge section 30 will be described in more detail. By providing the gear pump 60 immediately after the pyrolysis gasification apparatus 23, the vicinity of the outlet section 23f of the pyrolysis gasification apparatus 23 is sealed with resin. This prevents gas from leaking downstream. By preventing gas from leaking downstream, almost the entire amount (or most of the gas) is treated in the gas treatment section 100. This contributes to improving the yield and ensuring safe operation by preventing dangerous gas from leaking outside the system. Furthermore, the above-mentioned sealing effect prevents oxygen from outside the system from entering the system, so that the risk of explosions and the like within the system can be greatly reduced.

[0053] If the gear pump 60 is not provided, there is a possibility that the gas cannot be sealed if the amount of undecomposed residue generated in the pyrolysis gasification apparatus 23 is small. This is because the resin flows only in the lower part of the pyrolysis gasification apparatus 23, and the gas may pass through the upper part and reach the outlet part 23f. The gear pump 60 can block the resin and seal the gas with the blocked resin. On the other hand, if a sealing property is provided by providing a damming part or a backflow part in a screw configuration, if the decomposition rate decreases, the system may be clogged with undecomposed residue, and the gas may have nowhere to go. As a result, the internal pressure of the pyrolysis gasification apparatus 23 may increase, increasing the risk of explosion. According to this embodiment, the undecomposed residue can be quantitatively discharged, ensuring safety.

[0054] In addition, the gear pump 60 operates (on or speed controlled) and stops (off) according to the pressure value detected by the pressure gauge 28. By operating (on or speed controlled) and stopping (off) the gear pump 60 according to the pressure value, the undecomposed residue can be discharged reliably. This makes it possible to prevent the pressure from increasing too much, and to prevent blockage due to the undecomposed residue. In other words, by providing the pressure gauge 28 on the suction side (inlet side) of the gear pump 60, the amount of resin accumulated on the suction side can be estimated. This makes it possible to control the discharge rate of the gear pump 60 and discharge the undecomposed residue from the pyrolysis gasification device 23 while keeping the accumulated amount almost constant.

[0055] As described above, the thermometer 27 can be omitted, but there are advantages to using the thermometer 27. The thermometer 27 allows for more accurate control. As an example, the amount of residue filled in the pyrolysis gasification device 23 can be adjusted more precisely by controlling using both the pressure gauge 28 and the thermometer 27. That is, when the temperature is low, the viscosity of the residue increases, so the pressure may be high even if the amount of residue is small. Conversely, when the temperature is high, the viscosity of the residue decreases, so the pressure may be low even if the amount of residue is large. By controlling with both the thermometer and the pressure gauge, the viscosity of the residue can be predicted, and the difference in the amount of filling due to viscosity is eliminated. If a failure occurs in the pressure gauge 28, the rotation speed of the gear pump may become too high, and all the undecomposed residue may be discharged. As a result, the pyrolysis gas may reach the inlet of the gear pump 60. Since the temperature of the pyrolysis gas is higher than that of the undecomposed residue, the thermometer 27 can detect an abnormality. As an example of control, the gear pump 60 can be stopped (turned off) or the rotation speed of the gear pump 60 can be reduced using the signal output from the thermometer 27. Also, by installing a thermometer, abnormally high temperatures due to runaway reactions in the pyrolysis gasification apparatus can be detected early and a quick response can be made.

[0056] In addition, the gear pump 60 is operated intermittently or with its rotation speed varied, so that even when the pyrolysis gasification apparatus 23 is operated continuously, fluctuations in the amount of undecomposed residue inside the apparatus can be suppressed.

[0057] The gear pump 60 transfers fluid by meshing of the first gear 64A and the second gear 64B, which are rotating parts, and is therefore superior in gas sealing ability among positive displacement pumps.

[0058] Since most of the raw material is gasified by pyrolysis in the pyrolysis gasification device 23, the amount of residue discharged (discharged) from the outlet 23f (tip) is very small. By applying an extrusion type device such as a twin-screw rotating extruder as the pyrolysis gasification device 23 and filling the space between the tip of the screw 23a and the cylinder with residue, the tip of the screw 23a can be fixed. This is also advantageous from the viewpoint of protecting the device. In the case of a normal extrusion processing device, the same amount of raw material is discharged from the tip, so the inside of the device is filled with raw material. However, in the pyrolysis gasification device 23, the tip of the screw 23a becomes starved, so there is a possibility that a gap will be formed between the tip of the screw 23a and the cylinder. If the screw swings, there is a risk of damage to the device, but the device can be protected by utilizing the above-mentioned filling with residue.

[0059] Next, with reference to each of the figures from FIG. 3 onward, another example of the configuration of the residue discharge unit and its periphery will be described. The residue discharge unit 30A shown in FIG. 3 is connected to the discharge unit 62 of the gear pump 60 and further includes a flow path switching unit 33 that switches the flow path of the undecomposed residue discharged by the gear pump 60. The flow path switching unit 33 includes a main flow path 35 formed inside the main body unit 34 and connected to the residue discharge pipe 39, and an alternative flow path 36 connected to an external piping or the like other than the residue discharge pipe 39. The flow path switching unit 33 includes a switching unit 32 interposed between the discharge unit 62 and the main body unit 34 and serving as an actuator that switches the flow path into which the fluid is introduced to either the main flow path 35 or the alternative flow path 36. For example, a known diverter valve is applied as the flow path switching unit 33. Even if a high pressure state (such as blockage due to adhesion of undecomposed residue) occurs in the downstream residue discharge pipe 39 due to some trouble, the flow path switching unit 33 switches the flow path from the main flow path 35 to the alternative flow path 36 to discharge the undecomposed residue. The flow path switching unit 33 operates and switches the flow path according to a pressure value detected by, for example, a pressure gauge (not shown) provided downstream.

[0060] The configuration including the residue discharge unit 30A provides the same functions and effects as the pyrolysis device 1 including the above-mentioned residue discharge unit 30. Even if a high pressure state (such as a blockage) occurs downstream of the gear pump 60, the flow path can be switched from the main flow path 35 to the alternative flow path 36 to discharge the undecomposed residue.

[0061] The residue discharge section 30B shown in FIG. 4 further includes a chamber 37 provided between the outlet section 23f of the pyrolysis gasification apparatus 23 and the suction section 61 of the gear pump 60. The chamber 37 has an inlet 37a directly or indirectly connected to the outlet section 23f, an internal space S having a certain volume or more formed to communicate with the inlet 37a, a gas outlet 37b formed on the upper side of the internal space S, and a residue discharge port 37c formed on the lower side of the internal space S. The volume of the internal space S in the chamber 37 is preferably in the range of, for example, 1 / 6 to 1 / 2 of the amount of raw material supplied per hour. If the volume is too large, the residue may be cooled and solidified by storing it in the chamber for a long time, making it difficult to discharge it with a positive displacement pump, and if the volume is too small, it is not preferable because it does not have a volumetric buffer function. The chamber may also have a temperature adjustment function for heating, keeping, and cooling the residue. For example, a pyrolysis gas outlet pipe L30 is connected to the gas outlet 37b. 1, or may be connected to a part of the gas treatment unit 100 such as the condensation unit 40 separately from the pyrolysis gas discharge pipe L1. In this case, the pyrolysis gas discharge pipe L30 functions as a part of the pyrolysis gas separation unit A that separates the pyrolysis gas generated by pyrolysis in the pyrolysis gasification apparatus 23. The suction unit 61 of the gear pump 60 is connected to the residue discharge port 37c.

[0062] A more detailed explanation will now be given of an example of how the volume of the chamber 37 is considered. The volume of the chamber 37 is determined so that either of the following two conditions is satisfied. <First condition> The capacity must be equal to or larger than the internal capacity of the pyrolysis gasification apparatus 23. For example, if the pyrolysis gas outlet pipe L1, which is a vent pipe, becomes clogged due to some kind of trouble, the supply of raw material to the pyrolysis gasification apparatus 23 is stopped. At this time, in order to safely stop operation, the resin accumulated inside the pyrolysis gasification apparatus 23 can be discharged into the chamber 37. <Second condition> The capacity of the pyrolysis gasification apparatus 23 is set to 30 minutes' worth of the maximum supply amount [kg / h]. For example, when the maximum supply rate of the pyrolysis gasification apparatus 23 is 100 L / h, the capacity of the chamber 37 is set to be 50 L or more. As explained in the first condition, even if the pyrolysis gas outlet pipe L1, which is the vent pipe, becomes clogged due to some trouble and all of the gas or residue in the pyrolysis gasification apparatus 23 is discharged into the chamber 37, time can be secured for an operator to move to the site and the trouble can be dealt with manually (switching from automatic operation to manual operation, safely shutting down the operation, etc.).

[0063] According to the configuration including the residue discharge part 30B, the same action and effect as the pyrolysis device 1 including the above-mentioned residue discharge part 30 can be achieved. Also, in the chamber 37, gas can be taken out from the gas outlet 37b. The gas can be treated as an effective recovery component in a chemical recycling plant, similar to the pyrolysis gas recovered through the pyrolysis gas discharge pipe L1. Also, since a certain amount of undecomposed residue can be stored in the chamber 37, the gear pump 60 can be operated with a margin. Specifically, even if the downstream side of the gear pump 60 is blocked due to some factor, for example, the chamber 37 provides a time allowance until the pyrolysis device 1 needs to be stopped. Furthermore, since the chamber 37 functions as a volumetric buffer, the temperature of the undecomposed residue can be lowered in the chamber 37, and more general specifications can be applied to the discharge side of the gear pump 60 (i.e., special specifications can be avoided).

[0064] 5 further includes another gear pump (positive displacement pump) 60A provided between the outlet 23f of the pyrolysis gasification apparatus 23 and the chamber 37, in addition to the configuration of the residue discharge section 30B provided with the chamber 37. The configuration provided with the residue discharge section 30C provides the same effects and advantages as the pyrolysis apparatus 1 provided with the residue discharge section 30 described above. In addition, since two gear pumps 60, 60A are provided (positive displacement pumps are provided in two stages), the gas sealing effect described above is further enhanced.

[0065] Although the embodiment of the present disclosure has been described above, the present invention is not limited to the above embodiment. For example, the positive displacement pump is not limited to the gear pump 60. As the positive displacement pump in the residue discharge section, a screw pump, a vane pump, a rotary pump, a plunger pump, a piston pump, or the like may be applied. In a pump of a type in which a moving part reciprocates, such as a plunger pump or a piston pump, the "operation" of the pump means both control of the number of reciprocating motions of the moving part to be constant and control of the number of reciprocating motions of the moving part to be variable. In other words, a positive displacement pump of a reciprocating type is also operated intermittently or so as to make the number of reciprocating motions of the moving part variable. As a result, even when the pyrolysis gasification apparatus 23 is operated continuously, the fluctuation of the amount of undecomposed residue inside the apparatus can be suppressed.

[0066] In the control of the controller, a weight gauge may be used instead of or in addition to the pressure gauge. The weight gauge measures the weight of the fluid inside the pyrolysis gasification apparatus 23. The controller receives the measured value measured by the weight gauge and controls the operation of the gear pump 60.

[0067] The controller may be omitted. In that case, for example, the gear pump 60 is operated (on or by controlling the rotation speed) and stopped (off) based on a predetermined operation schedule.

[0068] A flow path switching unit 33 may be further applied to the residue discharging unit 30B including the chamber 37. In this case, the flow path switching unit 33 is connected to a discharge unit 62 of the gear pump 60.

[0069] The screw 23a of the pyrolysis gasification apparatus 23 may extend into the inside of the connection part 25. Furthermore, a part of the tip of the screw 23a may protrude into the chamber 37. By extending the screw 23a and making the tip protrude, the possibility of the resin being retained inside the connection part 25 can be reduced.

[0070] The pyrolysis device 1 may include a secondary-side gas separator that is connected to the discharge portion 62 of the gear pump 60 and separates the gas component contained in the undecomposed residue discharged by the gear pump 60. Examples of the secondary-side gas separator include a suction blower and a reduced-pressure gas suction device. The secondary-side gas separator can further reduce the amount of gas coexisting with the residue in the downstream of the residue discharge portion. Even when a granulation facility or the like is connected to the downstream (liquid side) of the secondary-side gas separator, the connection is easy. [Explanation of symbols]

[0071] DESCRIPTION OF THE PREFERRED EMBODIMENTS 1...pyrolysis apparatus, 20...pyrolysis section, 23...pyrolysis gasification apparatus, 23f...outlet section, 27...thermometer, 28...pressure gauge, 30, 30A, 30B, 30C...residue discharge section, 33...flow path switching section, 37...chamber, 37b...gas outlet, 40...condensation section, 50...purification section, 60...gear pump (positive displacement pump), 61...suction section, 62...discharge section, 100...gas processing section, A...pyrolysis gas separation section, S...internal space.

Claims

1. a pyrolysis section which receives and pyrolyzes raw resin; a pyrolysis gas separation section for separating a pyrolysis gas generated by pyrolysis in the pyrolysis section; a gas processing unit for processing the pyrolysis gas sent through the pyrolysis gas separation unit; a residue discharge section connected to an outlet of the pyrolysis section and configured to discharge undecomposed residue generated in the pyrolysis section; a pressure gauge or a weight gauge provided at or near the outlet of the pyrolysis section; A thermometer provided at or near the outlet of the pyrolysis section, The residue discharge unit includes a positive displacement pump that sucks in and discharges the undecomposed residue from the outlet unit, A pyrolysis apparatus, wherein the positive displacement pump operates and stops in response to either the pressure value in the pyrolysis section measured by the pressure gauge or the weight value of the fluid in the pyrolysis section measured by the weight gauge, and the temperature value in the pyrolysis section measured by the thermometer.

2. a pyrolysis section which receives and pyrolyzes raw resin; a pyrolysis gas separation section for separating a pyrolysis gas generated by pyrolysis in the pyrolysis section; a gas processing unit for processing the pyrolysis gas sent through the pyrolysis gas separation unit; A residue discharge section connected to an outlet of the pyrolysis section and discharging undecomposed residue generated in the pyrolysis section, The residue discharge unit includes: a positive displacement pump that sucks in and discharges the undecomposed residue from the outlet portion; a chamber provided between the outlet of the pyrolysis unit and the suction unit of the positive displacement pump, the chamber having an internal space of a certain volume or more and a gas outlet; A pyrolysis apparatus, wherein the volume of the internal space in the chamber is in the range of 1 / 6 to 1 / 2 of the amount of the raw material resin supplied per hour to the pyrolysis section.

3. 2. The pyrolysis apparatus according to claim 1, wherein the residue discharge unit further includes a flow path switching unit connected to a discharge unit of the positive displacement pump and switching a flow path for the undecomposed residue discharged by the positive displacement pump.

4. 2. The pyrolysis apparatus according to claim 1, wherein the residue discharge section is provided between the outlet section of the pyrolysis section and the suction section of the positive displacement pump, and further includes a chamber having an internal space of a certain volume or more and a gas outlet port.

5. 3. The pyrolysis apparatus according to claim 2, wherein the residue discharge section further comprises another positive displacement pump provided between the outlet of the pyrolysis section and the chamber.

6. The pyrolysis apparatus according to any one of claims 1 to 5, wherein the positive displacement pump is operated intermittently or so as to vary the number of rotations or reciprocating motions of the movable part.

7. The pyrolysis apparatus according to any one of claims 1 to 5, wherein the positive displacement pump is a gear pump.

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