Method and Reprocessing System for Reprocessing Plastic Waste Material, In Particular PET Waste Material

Abstract

In a method for reprocessing plastic waste material, in embodiments PET waste material, the plastic waste material is dried by a flash dryer in a conveying line and then fed into a multi-shaft screw machine. In the multi-shaft screw machine, the dried plastic waste material is reprocessed. Pre-drying enables simple, energy-efficient, economical, reliable and effective reprocessing.

Claims

1. A method for recycling plastic waste material comprising the following steps: providing plastic waste material (M.sub.W), drying the plastic waste material (M.sub.W) by a flash dryer (5) in a conveying line (7), feeding the dried plastic waste material (M.sub.D) into a multi-shaft screw machine (2), and reprocessing the dried plastic waste material (M.sub.D) by the multi-shaft screw machine (2).

2. The method according to claim 1, wherein the plastic waste material is PET waste material.

3. The method according to claim 1, wherein the plastic waste material (M.sub.W) is conveyed by a conveying gas (F) and dried while being conveyed to the multi-shaft screw machine (2).

4. The method according to claim 1, wherein a conveying gas (F) in the conveying line (7) has a temperature T.sub.G, wherein: 70° C.≤T.sub.G≤250° C.

5. The method according to claim 1, wherein the plastic waste material (M.sub.W) has a melting temperature T.sub.S and a conveying gas (F) in the conveying line (7) has a temperature T.sub.G, wherein: T.sub.S−100° C.≤T.sub.G<T.sub.S.

6. The method according to claim 1, wherein a mass m.sub.G of a conveying gas (F) is loaded with a mass m.sub.M of the plastic waste material (M.sub.W), wherein: 0.3≤m.sub.M/m.sub.G≤4.

7. The method according to claim 1, wherein a conveying gas (F) in the conveying line (7) has a conveying speed v.sub.G, wherein: 5 m/s≤v.sub.G≤50 m/s.

8. The method according to claim 1, wherein the plastic waste material (M.sub.W) has a dwell time t.sub.G in a conveying gas (F), wherein: 2 s≤t.sub.G≤10 s.

9. The method according to claim 1, wherein the plastic waste material (M.sub.W) is at least one of deflected and rotated and dispersed and decelerated and accelerated while being conveyed.

10. The method according to claim 1, wherein at least one of the plastic waste material (M.sub.W), when fed into a conveying gas (F), has a feed humidity proportion ψ.sub.1, wherein: 4000 ppm≤ψ.sub.1≤50000 ppm, and the dried plastic waste material (M.sub.D), when discharged from a conveying gas (F), has a discharge humidity proportion ψ.sub.2, wherein: 3000 ppm≤ψ.sub.2≤6000 ppm.

11. The method according to claim 1, wherein the processing of the dried plastic waste material (M.sub.D) is performed by the multi-shaft screw machine (2) with a throughput D, wherein: 500 kg/h≤D≤25000 kg/h.

12. The method according to claim 1, wherein the dried plastic waste material (M.sub.D) is melted and degassed in the multi-shaft screw machine (2).

13. The method according to claim 12, wherein the degassing takes place at a pressure p.sub.abs, wherein: 3 mbar≤p.sub.abs≤50 mbar.

14. A reprocessing system for reprocessing plastic waste material having a multi-shaft screw machine (2) for plasticizing and reprocessing the plastic waste material (M.sub.W), and a feeding apparatus (3) for feeding the plastic waste material (M.sub.D) into the multi-shaft screw machine (2), wherein the feeding apparatus (3) comprises a flash dryer (5) for drying the plastic waste material (M.sub.W) in a conveying line (7).

15. The reprocessing system according to claim 14, wherein the plastic waste material is PET waste material.

16. The reprocessing system according to claim 14, wherein the flash dryer (5) comprises a conveying line (7), a flow generator (8) for generating a flowing conveying gas (F) and a heating installation (10) for heating the conveying gas (F).

17. The reprocessing system according to claim 14, wherein the flash dryer (5) comprises a separating installation (11) for separating the dried plastic waste material (M.sub.D) from the conveying gas (F).

18. The reprocessing system according to claim 14, wherein the flash dryer (5) comprises at least one drying element (22, 23, 24, 26, 27, 28, 29, 30, 31) for improving the process of drying the plastic waste material (M.sub.W).

19. The reprocessing system according to claim 14, wherein at least one of the feeding apparatus (3) comprises a metering installation (4) for loading the plastic waste material (M.sub.W) into the flash dryer (5), and the feeding apparatus (3) comprises a metering installation (6) for feeding the dried plastic waste material (M.sub.D) into the multi-shaft screw machine (2).

20. The reprocessing system according to claim 14, wherein the multi-shaft screw machine (2) comprises at least one degassing installation (61) for degassing the dried plastic waste material (M.sub.D).

21. The reprocessing system according to claim 14, comprising a control installation (69) for controlling at least one of the feeding apparatus (3) and the multi-shaft screw machine (2).

Description

BRIEF DESCRIPTION OF THE DRAWING

[0059] FIG. 1 shows a schematic view of a reprocessing system for reprocessing plastic waste material, in embodiments PET waste material, having a feeding apparatus and a multi-shaft screw machine,

[0060] FIG. 2 shows an enlarged and sectional view of a flash dryer of the feeding apparatus in FIG. 1,

[0061] FIG. 3 shows a partially cut side view of the multi-shaft screw machine in FIG. 1, and

[0062] FIG. 4 shows a partial cutaway top view of the multi-shaft screw machine in FIG. 3.

DETAILED DESCRIPTION

[0063] A reprocessing system 1 shown in FIG. 1 serves for the reprocessing of moist plastic waste material M.sub.W. The plastic waste material M.sub.W is formed as PET waste material (PET: polyethylene terephthalate). The reprocessing system 1 comprises a multi-shaft screw machine 2 for plasticizing and reprocessing the plastic waste material, and a feeding apparatus 3 for feeding the plastic waste material into the multi-shaft screw machine 2.

[0064] The feeding apparatus 3 comprises a first metering installation 4, a flash dryer 5 and a second metering installation 6. The first metering installation 4 is used to load the moist plastic waste material M.sub.W into the flash dryer 5. The first metering installation 4 has, for example, a feed screw machine and/or a gravimetric metering unit and/or a volumetric metering unit.

[0065] The flash dryer 5 serves to dry the moist plastic waste material M.sub.W. The flash dryer 5 comprises a conveying line 7, a flow generator 8 for generating a conveying gas F flowing in a conveying direction 9, a heating installation 10 for heating the conveying gas F, and a separating installation 11 for separating the waste plastic material M.sub.D dried by the flash dryer 5 from the conveying gas F which is moist due to the process of drying.

[0066] The flow generator 8 has a conveying fan 12 which sucks in the conveying gas F via a suction line 13 and a filter 14 arranged therein. The conveying gas F is in embodiments air.

[0067] The heating installation 10 is connected to the flow generator 8 via a connection line 17 and is arranged downstream from the flow generator 8 in the conveying direction 9. The heating installation 10 comprises a heating device 15 for heating a heating fluid and a heat exchanger 16 connected to the heating device 15 for transferring thermal energy from the heating fluid to the flowing conveying gas F. The heating fluid is, for example, water, steam, thermal oil or a gas. The heat exchanger 16 is arranged within the connection line 17. Alternatively, the heating installation 10 can be designed for direct electrical heating of the conveying gas F.

[0068] The connection line 17 is connected to the conveying line 7 via a conveying gas feed opening 18. The conveying line 7 starts at a feed opening 19 for feeding the plastic waste material M.sub.W. The conveying line 7 leads to the separating installation 11 and opens into the separating installation 11. For this purpose, the conveying line 7 has a discharge opening 20. The conveying line 7 ends at the discharge opening 20. The conveying line 7 has a length L.sub.F from the feed opening 18 to the discharge opening 20, wherein in embodiments: 5 m≤L.sub.F≤100 m, in embodiments 10 m≤L.sub.F≤70 m, and in embodiments 20 m≤L.sub.F≤50 m. The conveying line 7 can be coated with an insulation layer 32 to reduce energy losses. The insulation layer 32 is only indicated in FIG. 1.

[0069] In the conveying direction 9, the conveying line 7 successively has a first horizontal line portion 21, a first deflection line portion 22, a first vertical line portion 23, a second deflection line portion 24, a second horizontal line portion 25, a third deflection line portion 26, a second vertical line portion 27, a fourth deflection line portion 28, and a cross-section change line portion 29. In the first horizontal line portion 21, a first direction changing component 30 is arranged, which is designed as a dispersing component. In the second horizontal line portion 25, a second direction-changing component 31 is arranged, which is designed as a swirl component. The deflection line portions 22, 24, 26, 28, the vertical line portions 23, 27, the cross-section change line portion 29, and the direction change components 30, 31 integrated in the horizontal line portions 21, 25 each form a drying element which serves to improve drying of the plastic waste material M.sub.W. Drying is accelerated by the respective drying element. The drying elements are part of the flash dryer 5.

[0070] The flash dryer 5 has a number N of drying elements in embodiments, wherein 1≤N≤20, in embodiments 2≤N≤16, and in embodiments 4≤N≤12. The conveying line 7 has a number U of deflection line portions in embodiments, wherein 1≤U≤10, in embodiments 2≤U≤8, and in embodiments 3≤U≤6.

[0071] The deflection line portions 22, 24, 26, 28 each enclose a deflection angle α, wherein in embodiments 10°≤α≤150°, in embodiments 15°≤α≤135°, and in embodiments 20°≤α≤120°.

[0072] The separating installation 11 serves to separate the dried plastic waste material M.sub.D from the conveying gas F which is moist due to the process of drying. The separating installation 11 is connected to the second metering installation 6 for feeding the dried plastic waste material M.sub.D. The separating installation 11 is further connected to a separator 33. The separator 33 serves to separate the fines A or dust contained in the conveying gas F. The separator 33 is part of the flash dryer 5.

[0073] The second metering installation 6 serves to feed the dried plastic waste material M.sub.D into the multi-shaft screw machine 2. The second metering installation 6 comprises, for example, a feed screw machine and/or a gravimetric metering unit and/or a volumetric metering unit. For feeding new plastic material M.sub.N, the feeding apparatus 3 has a third metering installation 34. The third metering installation 34 comprises, for example, a feed screw machine and/or a gravimetric metering unit and/or a volumetric metering unit.

[0074] The multi-shaft screw machine 2 serves to plasticize the dried plastic waste material M.sub.D and/or the new plastic material M.sub.N into a material melt M.sub.S and to process or reprocess the material melt M.sub.S into raw material M.sub.R. The multi-shaft screw machine 2 is configured as a co-rotating twin-shaft screw machine. The multi-shaft screw machine 2 comprises a housing 35 made of a plurality of housing portions 36 to 43 arranged one after the other. The housing portions 36 to 43 are joined together to form the housing 35. Two housing bores 44, 44′ are formed in the housing 35 parallel to each other and interpenetrating each other, which have the shape of a horizontal figure eight in cross-section. Two treatment element shafts 45, 45′ are arranged concentrically in the housing bores 44, 44′ and can be driven in rotation about associated axes of rotation 47, 47′ by a drive motor 46. A branching gear 48 and a coupling 49 are arranged between the treatment element shafts 45, 45′ and the drive motor 46. The treatment element shafts 45, 45′ are driven in the same direction, i.e. in the same directions of rotation about the axes of rotation 47, 47′, by the drive motor 46.

[0075] The multi-shaft screw machine 2 has, in succession in a conveying direction 9′, an intake zone 50, a plasticizing and homogenizing zone 51, a degassing zone 52 and a discharge zone 53.

[0076] In the intake zone 50, the housing portion 36 has a feed opening 54. An inlet hopper 55 opens into the feed opening 54. In the intake zone 50, the treatment element shafts 45, 45′ comprise screw elements 56, 56′, which are arranged in a rotationally fixed manner on associated shafts 57, 57′ and serve for conveying.

[0077] In the plasticizing and homogenizing zone 51, the dried plastic waste material M.sub.D and/or the new plastic material M.sub.N is plasticized or melted and the material melt M.sub.S is homogenized. For plasticizing and homogenizing, kneading elements 58, 58′ are arranged in a rotationally fixed manner on the shafts 57, 57′ in the plasticizing and homogenizing zone 51. In embodiments, kneading blocks are arranged on the shafts 57, 57′ in the plasticizing and homogenizing zone 51, which comprise a plurality of kneading disks formed in one piece with one another.

[0078] The degassing zone 52 serves for degassing the material melt M.sub.S. Degassing openings 59, 60 are formed in the housing portions 39, 42 for degassing. The multi-shaft screw machine 2 comprises a degassing installation 61 connected to the degassing openings 59, 60. The degassing installation 61 comprises a vacuum pump 62, which are connected to the degassing openings 59, 60 via degassing lines 63. In the degassing zone 52, screw elements 64, 64′ and kneading elements 65, 65′ are arranged on the shafts 57, 57′ in a rotationally fixed manner. In embodiments, kneading blocks are arranged in the degassing zone 52, which are formed from a plurality of kneading disks connected to one another in one piece.

[0079] In the discharge zone 53, screw elements 66, 66′ are arranged in a rotationally fixed manner on the shafts 57, 57′ in order to discharge the raw material MR. A nozzle plate 67 closing off the housing 35 is arranged on the last housing portion 43 and forms a discharge opening 68.

[0080] The reprocessing system 1 includes a control installation 69 for controlling the feeding apparatus 3 and/or the multi-shaft screw machine 2. The control installation 69 is in signal communication with the feeding apparatus 3 and the multi-shaft screw machine 2.

[0081] The functional principle of the reprocessing system 1 and a method for reprocessing the plastic waste material M.sub.W are described below:

[0082] The first metering installation 4 is supplied with the moist plastic waste material M.sub.W. The moist plastic waste material M.sub.W is comminuted and washed. The moist plastic waste material M.sub.W is transported, for example, in big bags. The plastic waste material M.sub.W has a melting temperature T.sub.S, wherein in embodiments: 250° C.≤T.sub.S≤260° C.

[0083] The conveying gas F is moved by the flow generator 8 in the conveying direction 9 at a conveying speed v.sub.G. The following applies in embodiments to the conveying speed v.sub.G in the conveying line: 5 m/s≤v.sub.G≤50 m/s, in embodiments 10 m/s≤v.sub.G≤45 m/s, and in embodiments 15 m/s≤v.sub.G≤40 m/s.

[0084] By the heating installation 10, the conveying gas F is heated and has a temperature T.sub.G in the conveying line 7. The following applies in embodiments to the temperature T.sub.G: 70° C.≤T.sub.G≤250° C., in embodiments 80° C.≤T.sub.G≤220° C., and in embodiments 90° C.≤T.sub.G≤190° C.

[0085] For the temperature T.sub.G, depending on the melting temperature T.sub.S, the following applies in embodiments: T.sub.S−100° C.≤T.sub.G<T.sub.S, in embodiments T.sub.S−80° C.≤T.sub.G≤T.sub.S−10° C., and in embodiments T.sub.S−60° C.≤T.sub.G≤T.sub.S−20° C.

[0086] The control installation 69 controls the first metering installation 4 and the flow generator 8 in such a way that a mass m.sub.G of the conveying gas F is loaded with a mass m.sub.M of the plastic waste material M.sub.W. The ratio m.sub.M/m.sub.G is also referred to as the load. For the load, the following applies in embodiments: 0.3≤m.sub.M/m.sub.G≤4, in embodiments 0.4≤m.sub.M/m.sub.G≤3, and in embodiments 0.5≤m.sub.M/m.sub.G≤2.

[0087] The plastic waste material M.sub.W has a feed humidity proportion ψ.sub.1 when being fed into the conveying gas F, wherein: 4000 ppm≤ψ.sub.1≤50000 ppm, in embodiments 5000 ppm≤ψ.sub.1≤35000 ppm, and in embodiments 6000 ppm≤ψ.sub.1≤20000 ppm. The plastic waste material M.sub.W is dried by the flash dryer 5 in the conveying line 7, so that the dried plastic waste material M.sub.D has a discharge humidity proportion ψ.sub.2 when being discharged from the conveying gas F, wherein: 3000 ppm≤ψ.sub.2≤6000 ppm, in embodiments 3500 ppm≤ψ.sub.2≤5500 ppm, and in embodiments 4000 ppm≤ψ.sub.2≤5000 ppm.

[0088] The feed humidity proportion ψ.sub.1 is defined as follows:

[00003]${\psi }_1=\frac{m_{W1}}{m_M}=\frac{m_M-m_{Mt}}{m_{W1}+m_{Mt}},$

[0089] wherein:

[0090] m.sub.W1 denotes the mass of moisture or water upon feeding,

[0091] m.sub.M denotes the mass of moist plastic waste material M.sub.W upon feeding,

[0092] m.sub.Mt denotes the mass of dry or anhydrous plastic waste material.

[0093] The discharge humidity proportion ψ.sub.2 is defined as follows:

[00004]${\psi }_2==\frac{m_{W2}}{m_{MD}}=\frac{m_{MD}-m_{Mt}}{m_{W2}+m_{Mt}},$

[0094] wherein:

[0095] m.sub.W2 denotes the mass of moisture or water upon discharge,

[0096] m.sub.MD denotes the mass of dried plastic waste material M.sub.D upon discharge.

[0097] The unit ppm is an abbreviation for “parts per million” and describes the mass m.sub.W1 or m.sub.W2 in mg in mg related to the mass m.sub.M or m.sub.MD in kg.

[0098] The moisture or humidity is composed of an internal humidity bound in the plastic waste material M.sub.W or M.sub.D and a surface humidity. Accordingly, the feed humidity proportion ψ.sub.1 is composed of an internal humidity ψ.sub.I and a surface humidity ψ.sub.O1. The following applies:

ψ.sub.1=ψ.sub.I+ψ.sub.O1.

[0099] The internal humidity proportion ψ.sub.I is bound in the plastic waste material M.sub.W or M.sub.D and remains essentially constant despite the process of drying the plastic waste material M.sub.W by the flash dryer 5. In contrast, the surface humidity proportion ψ.sub.O1 is located on the surface of the plastic waste material M.sub.W and is removed by the process of drying by the flash dryer 5 to at least 70% by weight, in embodiments to at least 80% by weight, and in embodiments to at least 90% by weight. The following thus applies to the discharge humidity proportion ψ.sub.2:

ψ.sub.2=ψ.sub.I+ψ.sub.O2,

[0100] wherein ψV.sub.O2 denotes the surface humidity proportion upon discharge of the dried plastic waste material M.sub.D. The following applies in embodiments:

[0101] 0 ppm≤ψ.sub.O2≤3000 ppm, in embodiments 100 ppm≤ψ.sub.O2≤2500 ppm, and in embodiments 300 ppm≤ψ.sub.O2≤2000 ppm.

[0102] The plastic waste material M.sub.W is conveyed by the conveying gas F in co-current in the conveying line 7 and dried while being conveyed to the multi-shaft screw machine 2. The drying elements improve the drying or the drying effect and accelerate the drying process of the plastic waste material M.sub.W. At least one force is exerted on the plastic waste material M.sub.W by the drying elements, thereby improving the drying effect. The plastic waste material M.sub.W is dispersed in the first horizontal line portion 21 by the first direction change component 30 or the dispersing component, and then deflected by the deflection angle α by the first deflection line portion 22. The forces thereby exerted on the plastic waste material M.sub.W enhance the drying effect and accelerate the process of drying. In the first vertical line portion 23, the conveying speed v.sub.G is reduced due to gravity. As a result of the deceleration, on the one hand a force is exerted on the plastic waste material M.sub.W and on the other hand a dwell time t.sub.G of the plastic waste material M.sub.W in the conveying gas F is increased. By the second deflection line portion 24, the plastic waste material M.sub.W is again deflected by a deflection angle α, then rotated in the second horizontal line portion 25 by the second direction change component 31 or the swirl component, and again deflected by a deflection angle α by the third deflection line portion 26. The forces exerted through this enhance the drying effect and accelerate the drying process. Due to the second horizontal line portion 25, the plastic waste material M.sub.W is accelerated again in the meantime and then decelerated again in the second vertical line portion 27. By the second vertical line portion 27, the dwell time t.sub.G can be further increased. Subsequently, by the fourth deflection line portion 28, the plastic waste material M.sub.W is again deflected by a deflection angle α and first accelerated and then decelerated again in the horizontally arranged cross-section change line portion 29. The forces exerted through this enhance the drying effect and accelerate the drying process. The plastic waste material M.sub.W has a dwell time t.sub.G in the conveying line 7 or in the conveying gas F, wherein, in embodiments: 2 s≤t.sub.G≤10 s, in embodiments 3 s≤t.sub.G≤8 s, and in embodiments 3 S≤t.sub.G≤6 s. When the plastic waste material M.sub.W exits the conveying line 7 through the discharge opening 20, it is referred to as dried plastic waste material M.sub.D.

[0103] By the separating installation 11, the dried plastic waste material M.sub.D is separated from the moist conveying gas F. The dried plastic waste material M.sub.D is fed to the second metering installation 6. The moist conveying gas F is fed to the separator 33, in which the fines A are separated. The filtered conveying gas F flows back into the environment or to the flow generator 8, so that the heat or thermal energy of the conveying gas F can be used again via heat exchangers.

[0104] The plastic waste material M.sub.W is heated by a temperature ΔT by the flash dryer 5. In embodiments, the following applies to the temperature ΔT: 2° C.≤ΔT≤80° C., in embodiments 5° C.≤ΔT≤70° C., and in embodiments 10° C.≤ΔT≤60° C.

[0105] The plastic waste material M.sub.D is fed to the multi-shaft screw machine 2 after the flash dryer 5, in embodiments without further heating and/or further drying. The dried plastic waste material M.sub.D is fed to the multi-shaft screw machine 2 in embodiments at a temperature T.sub.K, wherein for the temperature T.sub.K in embodiments applies: 0° C.≤T.sub.K≤100° C., in embodiments 10° C.≤T.sub.K≤90° C., in embodiments 20° C.≤T.sub.K≤80° C., in embodiments 30° C.≤T.sub.K≤70° C., and in embodiments 40° C.≤T.sub.K≤60° C. The dried plastic waste material M.sub.D is fed to the multi-shaft screw machine 2, in embodiments in a non-crystallized state.

[0106] The dried plastic waste material M.sub.D is fed by the second metering installation 6 via the inlet hopper 55 and the feed opening 54 into the multi-shaft screw machine 2. If desired or necessary, new plastic material M.sub.N can be fed into the multi-shaft screw machine 2 by the third metering installation 34 via the inlet hopper 55 and the feed opening 54.

[0107] The fed plastic waste material M.sub.D and/or the new plastic material M.sub.N is conveyed in the intake zone 50 in the conveying direction 9′ to the plasticizing and homogenizing zone 51. In the plasticizing and homogenizing zone 51, the plastic waste material M.sub.D and/or the new plastic material M.sub.N is plasticized and homogenized. Plasticizing releases the internal humidity bound in the plastic waste material M.sub.D. The released internal humidity and any remaining surface humidity are removed from the housing bores 44, 44′ in the degassing zone 52. For this purpose, a pressure p.sub.abs is generated by the vacuum pump and the humidity prevailing in the housing bores 44, 44′ is extracted via the degassing openings 59, 60 and the degassing lines 63. For the pressure p.sub.abs upon degassing, the following applies in embodiments: 3 mbar≤p.sub.abs≤50 mbar, in embodiments 5 mbar≤p.sub.abs≤30 mbar, in embodiments 10 mbar≤p.sub.abs≤25 mbar, and in embodiments 15 mbar≤p.sub.abs≤20 mbar.

[0108] Due to the fact that the surface humidity has been essentially completely removed from the moist plastic waste material M.sub.W by the flash dryer 5, only the internal humidity, i.e. considerably less humidity, has to be removed from the material melt M.sub.S, which has been generated from the dried plastic waste material M.sub.D. This means that the degassing installation 61 can be of smaller dimensions and operated at a lower pressure p.sub.abs.

[0109] The material melt M.sub.S has a temperature T.sub.M in the degassing zone 52, wherein in embodiments: 265° C.≤T.sub.M≤300° C., in embodiments 270° C.≤T.sub.M≤285° C. The dwell time v.sub.M of the material melt M.sub.S in the degassing zone 52 is in embodiments between 10 s and 45 s, and in embodiments between 15 s and 30 s. Related to 1 kg of material melt M.sub.S, the degassing installation 61 is operated with a volume flow rate of 0.3 m.sup.3/kg to 2.5 m.sup.3/kg, in embodiments 0.5 m.sup.3/kg to 1.5 m.sup.3/kg, and in embodiments 0.6 m.sup.3/kg to 1.2 m.sup.3/kg.

[0110] Through plasticizing, homogenizing and degassing, the plastic waste material M.sub.D is processed or reprocessed into new raw material M.sub.R. The resulting raw material M.sub.R is then discharged via the discharge zone 53 through the discharge opening 68. The raw material M.sub.R can then be further treated in the usual way, for example filtered and/or granulated.

[0111] Due to the fact that dried plastic waste material M.sub.D is fed to the multi-shaft screw machine 2, the processing by the multi-shaft screw machine 2 can be performed with a higher throughput D. For the throughput D, the following applies in embodiments: 500 kg/h≤D≤25000 kg/h, in embodiments 1000 kg/h≤D≤20000 kg/h, and in embodiments 1500 kg/h≤D≤15000 kg/h.

[0112] The flash dryer 5 enables simple, energy-efficient and economical drying of the moist plastic waste material M.sub.W. The flash dryer 5 requires little space, has low energy consumption and low investment and operating costs. The plastic waste material M.sub.W is gently dried. Drying simplifies subsequent reprocessing by the multi-shaft screw machine 2. Due to the fact that less humidity has to be removed from the multi-shaft screw machine 2, the degassing installation 61 can be of smaller dimensions and operated at a lower pressure p.sub.abs. As a result, the throughput D can be increased. Overall, the method or the reprocessing system 1 enables simple, energy-efficient, economical, reliable and effective reprocessing of the plastic waste material M.sub.W, in embodiments of PET waste material.