Method for oiling plastics

Abstract

The invention relates to a system (1) and a method for oiling plastics, wherein the plastic material to be oiled is introduced into a conveying container (4) of a conveying device (2) through a filling opening (5), is transported in the conveying container (4) through at least one conveying screw (7) to an outlet opening (6) of the conveying container (4) and is thereby compressed and the plastic material exiting the outlet opening (6) is fed to a pyrolysis device (3), in which the plastic material is subjected to a pyrolysis process, wherein a circulating fluid (F) having liquid plastic material is produced by means of the pyrolysis process, and at least one portion of the circulating fluid (F) is returned to the conveying container (4) through a return line (10) in a return position (PR) provided between the filling opening (5) and the outlet opening (6).

Description

[0001] Methods for oiling plastics

[0002] The invention relates to a method for oiling plastics, wherein the plastic material to be oiled is introduced through a filling opening into a conveying container of a conveying device, is transported in the conveying container by at least one screw conveyor to an output opening of the conveying container and is thereby compacted, and the plastic material exiting the output opening is fed to a pyrolysis device in which the plastic material is subjected to a pyrolysis process.

[0003] The invention further relates to a system for the oiling of plastics with a conveying device for the plastics and a pyrolysis device following the conveying device, wherein the conveying device has a conveying container with a filling opening and a discharge opening and with at least one conveying screw arranged in the conveying container between the filling opening and the discharge opening.

[0004] Processes and systems for the oiling of plastics are known. In these processes, the plastic material is fed into an extruder, which conveys the material with a screw conveyor, partially or completely melting it in the process. The partially or completely melted plastic material is then fed into a pyrolysis section of the system, where the plastic is broken down at high temperatures and largely without oxygen. The energy required to melt the plastic material is supplied by friction between the rotating screw conveyor and the plastic material, by heat transfer from the cylinder to the plastic material, and optionally via rotating bolts or blades of a PCU (Pre-Conditioning Unit). The extruder also generates the necessary pressure to force the molten plastic material through a melt line into the pyrolysis section.

[0005] WO 2023 / 036751 Al relates to a separation device and a corresponding method for separating vaporous, liquid, and solid components of a multiphase hydrocarbon stream. The separation device is part of a plastics processing plant in which plastic material is fed to an extruder where it is compacted, melted, and / or degassed. The molten plastic material is mixed in a static mixer with an external solvent, preferably heavy oil, and / or at least a portion of the solids-reduced product stream obtained from the separation device to reduce the viscosity of the plastic melt. The resulting mixture is then fed into a cracking reactor where the plastic is depolymerized. The multiphase hydrocarbon stream is obtained from the cracking reactor and fed into the separation device.

[0006] A disadvantage of the known processes and systems is the high energy consumption involved in processing the plastics.

[0007] The object of the invention is to provide a method and a system as described above, which avoid or at least reduce the disadvantages of the prior art. In particular, the method should be as energy-efficient and cost-effective as possible. The system should enable the energy-efficient and cost-effective implementation of the method.

[0008] This problem is solved by a method according to claim 1 and by a system according to claim 10. Advantageous embodiments and further developments are specified in the dependent claims.

[0009] The process is characterized in that a circulating fluid containing liquid plastic material is generated during the pyrolysis process, and at least a portion of this fluid is returned to the conveying container via a return line at a return point located between the inlet and outlet openings. The process thus serves to oil plastics. The plastics to be oiled can be meltable, for example, PE (polyethylene) and PP (polypropylene), or non-meltable. The plastic material to be oiled is introduced into the conveying container of the conveying device through the inlet opening. The inlet opening is a filling opening of the conveying container. The conveying device can be an extruder.The plastic material to be oiled, which is placed in the conveying container, is transported within the container by at least one screw conveyor to an outlet opening and compacted in the process. The plastic material exiting the outlet opening is fed to the pyrolysis unit, where it undergoes a pyrolysis process. As is known, the pyrolysis process involves breaking down the plastic material at high temperatures and largely without oxygen.

[0010] To minimize the energy required for oiling the plastics introduced into the conveying container, the pyrolysis process is designed to generate a circulating fluid containing the plastic material. At least a portion of this circulating fluid is then returned to the conveying container via a return line at a point located between the inlet and outlet openings. Since the pyrolysis process occurs at temperatures high enough to break down the plastic material, the circulating fluid produced is also at a higher temperature than the plastic material introduced into the conveying container.The plastic material received in the conveying container can thus be heated both by energy supplied via the conveying device, for example, frictional heat, and by the heat of the liquid returned to the conveying container. The pyrolysis process can be carried out very energy-efficiently, so that the circulating liquid produced by the pyrolysis process is also heated very energy-efficiently. In contrast, heating of the plastic material received in the conveying container by the conveying device, especially through friction, occurs with lower energy efficiency. Possible reasons for this include the small contact area of ​​the screw conveyor with the plastic material and a decreasing viscosity of the plastic material towards the discharge opening, whereby this decreasing viscosity reduces the energy input into the plastic material by the screw conveyor.By returning at least some of the circulating fluid generated during the pyrolysis process to the conveying vessel and mixing it with the plastic material, the plastic material in the conveying vessel is also heated energy-efficiently. Because of this heating of the plastic material by the recirculated fluid, the energy required for heating the plastic material by the conveying device, for example through friction, can be reduced. Overall, heating the plastic material by the fluid is therefore more energy-efficient than heating it by the conveying device alone. The plastic material, already preheated in the conveying vessel, can then be heated to the pyrolysis temperature in the pyrolysis unit with less energy expenditure.

[0011] The circulating liquid produced during the pyrolysis process can typically contain 5% to 100% by weight, preferably 50% to 95% by weight, and particularly 70% to 90% by weight of liquid plastic material. The circulating liquid consists of a partially pyrolyzed liquid plastic material and another liquid, in particular a solvent. The solvent, if present in the circulating liquid, can be added to the plastic material before or after melting, or before or during a cracking or pyrolysis process.

[0012] Depending on how much recycled liquid is generated by the pyrolysis process and how much of this liquid is to be recycled—for example, how much of the recycled liquid can be absorbed by the plastic material in the conveying container—only a portion of the liquid plastic material generated by the pyrolysis process can be recycled back into the conveying container. Recycling the recycled liquid, or a portion thereof, generated by the pyrolysis process refers to recycling a specific quantity of liquid per unit of time, i.e., a volumetric flow rate.

[0013] When the description refers to locations and directions such as "above", "below", "front", "back", "upstream" or "downstream", these refer to the intended state of use of the system. The term "vertical" means in the direction of gravity, from "above" to "below", or vice versa.

[0014] According to a preferred embodiment of the inventive method, it can be provided that only a portion of the circulating fluid generated by the pyrolysis process is returned to the conveying vessel as a first portion, and a second portion of the circulating fluid generated by the pyrolysis process is mixed with the plastic material exiting the discharge opening. The first and second portions are volumetric flows. Furthermore, the first and second portions can vary over time. A mixer can be provided between the discharge opening and the pyrolysis device in which the plastic material exiting the discharge opening is mixed with the second portion of the circulating fluid to reduce the viscosity of the plastic material. Alternatively, the second portion of the circulating fluid can be introduced without a mixer into a connecting line that links the discharge opening to the pyrolysis device.Adding the second portion of the recirculating fluid to the plastic material exiting the discharge opening is advantageous for the subsequent pyrolysis process and prevents unwanted backflow of the recirculating fluid through the conveying vessel to the feed opening and fluid leakage from the feed opening. Preferably, the ratio between the first and second portions is selected such that the first portion is defined by the maximum volume flow of the recirculating fluid that can be absorbed by the plastic material in the conveying vessel. The remaining volume flow of the generated recirculating fluid can constitute the second portion. If not all of the recirculating fluid generated by the pyrolysis process is to be used in the process, a third portion of the volume flow of the recirculating fluid generated by the pyrolysis process can be discharged from the system.The maximum volume flow rate of the circulating fluid that can be absorbed by the plastic material in the conveying container depends, among other things, on the plastic material itself, the density of the plastic material in the conveying container, the conveying speed of the screw conveyor, and the cross-section and pressure over which the recycled fluid is introduced into the plastic material in the conveying container.

[0015] Furthermore, it may be provided that additional liquid is taken from a liquid container and introduced into the conveying vessel at a feed point located between the filling opening and the discharge opening, and / or added to the plastic material exiting the discharge opening. In this way, a process-defined volume flow of liquid can be added to the plastic material in the conveying vessel or to the plastic material already exiting the conveying vessel, even if the pyrolysis process does not generate a sufficient quantity of recyclable circulating fluid and therefore the volume flow of the recyclable circulating fluid falls below a target value. The additional liquid can have the same composition as the recyclable liquid or be a different liquid.

[0016] Preferably, the recycled circulating fluid and / or the additional fluid has a lower viscosity than the plastic material into which the recycled circulating fluid and / or the additional fluid is introduced.

[0017] It is advantageous if the circulating fluid produced by the pyrolysis process is returned to the conveying vessel at a temperature and / or mixed with the plastic material exiting the discharge opening, and / or if the additional fluid from the liquid reservoir is introduced into the conveying vessel at a temperature and / or mixed with the plastic material exiting the discharge opening, which is lower than the pyrolysis temperature of the pyrolysis process but higher than the temperature of the plastic material at the associated feed point, return point, or discharge opening, and in particular higher than the melting point of the plastic material. By ensuring the temperature is lower than the pyrolysis temperature of the pyrolysis process, pyrolysis occurring outside the pyrolysis device is avoided.The pyrolysis temperature of the pyrolysis process is understood to be the temperature at which the pyrolysis of the circulating fluid and / or the plastic material mixed with the additional liquid is carried out. The temperature of the circulating fluid or the additional liquid is preferably higher than the temperature of the plastic material at the point where the circulating fluid and / or the additional liquid is added to the plastic material. Thus, the temperature of the recirculated liquid is preferably higher than the temperature of the plastic material at the recirculation point. The temperature of the recirculated circulating fluid can also be higher than the temperature of the plastic material between the outlet opening and the pyrolysis device if the recirculated liquid plastic material is mixed with the plastic material exiting the outlet opening.The temperature of the additional liquid can be higher than the temperature of the plastic material at the feed point when additional liquid is introduced into the conveying hopper. Furthermore, the temperature of the additional liquid can be higher than the temperature of the plastic material between the discharge opening and the pyrolysis unit when the additional liquid is mixed with the plastic material exiting the discharge opening. If the recirculated liquid and / or the additional liquid is higher than the melting point of the plastic material, the plastic material can be heated particularly efficiently by the recirculated and / or additional liquid. Upon mixing with the plastic material, the liquid can cool below the melting point of the plastic material.For example, the temperature of the liquid plastic material taken from the pyrolysis device is between 350°C and 400°C. The temperature of the liquid taken from the pyrolysis device can be reduced before it is added to the plastic material.

[0018] It can be particularly advantageous that the plastic material received in the conveying container is at least partially melted by frictional energy introduced by the conveying device and by the recirculating fluid generated by the pyrolysis process and / or by the additional fluid drawn from the liquid reservoir. This further reduces the viscosity of the plastic material, which is advantageous for transporting the plastic material to the pyrolysis device. The recirculating fluid generated and returned by the pyrolysis process and / or the additional fluid preferably has a temperature higher than the melting point of the plastic material. A higher fluid temperature reduces the comparatively inefficient energy input by the conveying device, for example, by the screw conveyor.

[0019] To prevent backflow of the circulating fluid returned to the conveying container at the return position or of the additional fluid introduced into the conveying container at the feed position towards the filling opening, it may be provided that the plastic material received in the conveying container is more compacted between the return position and the filling opening than between the return position and the discharge opening and / or that the plastic material received in the conveying container is more compacted between the feed position and the filling opening than between the feed position and the discharge opening.The comparatively higher density of the plastic material between the return position and the filling opening, or the comparatively higher density of the plastic material between the feed position and the filling opening if an additional liquid is introduced, acts as a liquid barrier, causing the liquid to spread in the area of ​​lower density and mix with the plastic material. At least one screw conveyor is suitably designed to achieve the different compactions within the conveying container.

[0020] If the feed position is located at the same distance from the filling opening as the return position, and especially if the feed position is located at the return position, the conveying container can be manufactured cost-effectively. The feed position and the return position can therefore be the same.

[0021] It is particularly preferred that oil is used as a recirculating fluid produced by the pyrolysis process and / or as additional fluid taken from the liquid container. Thus, the oil obtained from the plastic material during the pyrolysis process can be returned to the conveying container and / or added to the plastic material exiting the discharge opening. Likewise, the oil obtained from the plastic material during the pyrolysis process can be stored in the liquid container and, as needed, introduced into the conveying container and / or added to the plastic material exiting the discharge opening.

[0022] As mentioned at the beginning, the invention also relates to a system for the oiling of plastics.

[0023] The system for oiling plastics is characterized in that a return inlet of the conveying container is connected at a return position provided between the filling opening and the discharge opening to a return line leading from a liquid outlet of the pyrolysis device back to the conveying device, in which a circulating fluid containing liquid plastic material from the pyrolysis device is received. The system thus comprises a conveying device for the plastics to be oiled and a pyrolysis device following the conveying device and connected to it. The conveying device includes a conveying container with a filling opening and a discharge opening and with at least one screw conveyor arranged in the conveying container between the filling opening and the discharge opening.Preferably, the conveying device is designed to heat the plastic material contained in the conveying container, at least by friction. The friction can be caused by the screw conveyor and / or by other rotating parts, such as bolts or blades. The filling opening can be surrounded by a filling hopper designed to receive the plastic material. The pyrolysis device includes a heating element for breaking down the plastic material at high temperatures and can also include further components, such as a separation device for separating the liquid produced from the solids generated by the pyrolysis.To return the relatively warm liquid produced by the pyrolysis unit to the conveying tank and thereby preheat the plastic material in the tank, the return inlet of the conveying tank is connected at the return position to the return line leading from the liquid outlet of the pyrolysis unit back to the conveying unit. The return line is a fluid line for conveying the liquid plastic material. In an operating state of the system, at least some of the circulating fluid produced by the pyrolysis unit is contained in the return line.

[0024] Regarding the characteristics of the plant, reference is also made to the preceding description of the process, insofar as this description is helpful for understanding the plant and insofar as characteristics of the plant can be derived from this description of the process. Likewise, reference is made to the description of the plant with regard to the characteristics of the process.

[0025] According to a preferred embodiment of the inventive system, a material inlet of the pyrolysis device, connected to the output opening via a connecting line, can be connected to the return line and / or to an additional return line leading back from the liquid outlet of the pyrolysis device, in which the circulating liquid from the pyrolysis device is received. The material inlet can be connected to the return line via a section of the connecting line. The plastic material mixed with the liquid is introduced into the pyrolysis device through the material inlet. The connecting line is a fluid line for the plastic material mixed with the liquid.An additional return line may also be provided between the liquid outlet of the pyrolysis device and the material inlet in order to allow further liquid from the pyrolysis device to be returned to the pyrolysis device without mixing with the plastic material.

[0026] If an outlet of a liquid container is connected to a feed inlet of the conveying container at a feed point located between the filling opening and the discharge opening, additional liquid can be introduced from the liquid container into the conveying container as needed. This is particularly advantageous if the pyrolysis device does not provide the volume flow of liquid required for mixing with the plastic material. The liquid container is preferably located outside the pyrolysis device.

[0027] If the outlet of the liquid container is connected to the material inlet of the pyrolysis device via a liquid-conducting connection, additional liquid can be introduced from the liquid container into the pyrolysis device as needed, bypassing the conveying container. This is particularly advantageous if the viscosity of the plastic material exiting the conveying container needs to be reduced.

[0028] It is particularly preferred if the plastic material to be oiled is contained in the conveying vessel and the circulating fluid from the pyrolysis device and / or the additional fluid from the liquid container has a temperature below the pyrolysis temperature in the pyrolysis device but above the temperature of the plastic material at the associated feed point, return point, and / or connection point with the connecting line, and in particular a temperature above the melting point of the plastic material. In this way, pyrolysis outside the pyrolysis device is avoided, while the plastic material in the conveying vessel is preheated by the fluid.If the liquid temperature is above the melting point of the plastic material, preheating of the plastic material can be particularly efficient. The associated feed position refers to the feed point on the conveying tank when the outlet of the liquid tank is connected to the conveying tank. The associated return position refers to the return position on the conveying tank. The associated connection point with the connecting line refers to the connection point between the return line and the connecting line when the circulating liquid from the pyrolysis unit is introduced into the pyrolysis unit, bypassing the conveying tank.In contrast, the associated connection point with the connecting line is understood to be the connection point between a container line leading away from the outlet of the liquid container and the connecting line, when the additional liquid from the liquid container is introduced into the pyrolysis device bypassing the conveying container.

[0029] If the plastic material to be oiled is contained in the conveying container and has a higher density between the return position and the filling opening than between the return position and the discharge opening, and / or if the plastic material to be oiled is contained in the conveying container and has a higher density between the feed position and the filling opening than between the feed position and the discharge opening, backflow of the circulating fluid at the return position or of the additional fluid introduced into the conveying container at the feed position towards the filling opening can be prevented. Accordingly, the conveying device can be designed to compress the plastic material more highly between the return position and the filling opening than between the return position and the discharge opening.Additionally or alternatively, the conveying device can be designed to compress the plastic material more highly between the feed position and the filling opening than between the feed position and the dispensing opening.

[0030] For a simple and cost-effective system design, it is advantageous if the feed point and the return point are located at the same distance from the filling opening, and in particular, if the feed point is also the return point and the feed inlet is also the return inlet. Since this allows the circulating fluid from the pyrolysis unit and the additional fluid from the liquid reservoir to be introduced into the conveying tank at the same distance from the filling opening, the conveying tank can be designed more simply. If the feed inlet is also the return inlet, only one liquid inlet to the conveying tank is required.

[0031] Preferably, the circulating fluid from the pyrolysis device is an oil produced in the pyrolysis device.

[0032] Furthermore, it is advantageous if the plastic material to be treated with oil is contained in the conveying vessel and at least partially melted. This further reduces the viscosity of the plastic material, which is beneficial for transporting the plastic material to the pyrolysis unit. The circulating fluid generated and recirculated during the pyrolysis process and / or the additional fluid from the liquid reservoir preferably has a temperature higher than the melting point of the plastic material.

[0033] The invention will be further explained below with reference to preferred, non-limiting embodiments and the drawings. The drawings show:

[0034] Fig. 1 shows a system according to the invention in a simplified symbolic representation;

[0035] Fig. 2 shows a conveying container of the system from Fig. 1 with two screw conveyors in a simplified symbolic representation; and

[0036] Fig. 3 shows a flow diagram of the method according to the invention.

[0037] It should be noted that Figures 1 and 2 are not necessarily shown to scale.

[0038] Fig. 1 shows a plant 1 for the oiling of plastics and, in particular, for carrying out the previously described process. The plant 1 has a conveying device 2 for the plastics and a pyrolysis device 3 following the conveying device 2 in the direction of a flow path SK of the plastics and connected to the conveying device 2. The conveying device 2 has a conveying container 4 with a filling opening 5 and a discharge opening 6. At least one screw conveyor 7 is arranged in the conveying container 4 between the filling opening 5 and the discharge opening 6. In the example according to Fig. 2, two parallel screw conveyors 7 are shown. The conveying container 4 also has a return inlet 8 at a return position PR provided between the filling opening 5 and the discharge opening 6.The return inlet 8 is connected to a return line 10 leading from a liquid outlet 9 of the pyrolysis device 3 back to the conveying device 2. In an operating state of the system 1, the return line 10 receives a circulating fluid F containing liquid plastic material, which is discharged from the liquid outlet 9 and thus warmed compared to the solid plastic material, from the pyrolysis device 3. The circulating fluid F is generated in the pyrolysis device 3 and flows along flow paths SF. Thus, the circulating fluid F containing liquid plastic material is returned from the pyrolysis device 3 to the conveying container 4, thereby preheating the solid plastic material in the conveying container 4, for example, by at least partially melting it. The circulating fluid F from the pyrolysis device 3 can be an oil generated in the pyrolysis device.The circulating liquid F from the pyrolysis device 3 can, for example, contain 95% waxes and 5% solids.

[0039] The conveying device 2 can have a filling funnel 11 for receiving the plastic material, which surrounds the filling opening 5.

[0040] The conveying device 2, in particular the discharge opening 6 of the conveying container 4, can be connected via a connecting line 12 to a material inlet 13 of the pyrolysis device 3 in order to introduce the plastic material exiting the discharge opening 6 and mixed with the circulating fluid F into the pyrolysis device 3. In the illustrated example, the material inlet 13 is also connected via a section of the connecting line 12 to the return line 10 in order to introduce the circulating fluid F into the pyrolysis device 3, bypassing the conveying container 4. Furthermore, the material inlet 13 can be connected to an additional return line 14 leading back from the liquid outlet 9 of the pyrolysis device 3, in which the circulating fluid F from the pyrolysis device 3 is received. Finally, according to the example shown in Fig. 1, a liquid container 15 can be provided for receiving an additional liquid FZ.To introduce the additional liquid FZ into the conveying container 4, an outlet 16 of the liquid container 15 is connected via a container line 17 to a feed inlet 18 of the conveying container 4. The feed inlet 18 is located at a feed position PE between the filling opening 5 and the discharge opening 6. In the illustrated example, the feed position PE is located at the same distance from the filling opening 5 as the return position PR. In particular, the feed position PE is also the return position PR, and the feed inlet 18 is also the return inlet 8. Thus, the circulating liquid F from the pyrolysis device 3 and the additional liquid FZ from the liquid container 15 can be fed into the conveying container 4 at the same position.Furthermore, the outlet 16 of the liquid container 15 can be connected to the material inlet 13 of the pyrolysis device 3 in a liquid-conducting manner, in order to supply the additional liquid FZ to the pyrolysis device 3, bypassing the conveying container 4. For this purpose, the container line 17 leading away from the outlet 16 of the liquid container 15 can be connected to the connecting line 12 at a connection point PV. In addition, an outlet 16a of the liquid container 15 can be connected to an inlet side of the conveying device 2 in a liquid-conducting manner, so that additional liquid FZ can be supplied to the plastic material before it enters the filling opening 5. Fig. 1 shows possible flow paths SFZ of the additional liquid FZ.

[0041] Figure 1 also shows that the pyrolysis device 3 can have a heating device 19, in particular a cracking reactor 19a, in which the plastic material exiting the conveying vessel 4 and mixed with the circulating fluid F and / or the additional fluid FZ is cracked at high temperatures. The pyrolysis device 3 can also have a separation device 20 downstream of the heating device 19, for example by connecting an outlet 21 of the heating device 19 to an inlet 22 of the separation device 20. The separation device 20 is designed to separate the circulating fluid F produced during the pyrolysis from solids produced during the pyrolysis. An example of such a separation device 20 is known from publication WO 2023 / 036751 A1 by OMV DOWNSTREAM GmbH.

[0042] Figure 1 further shows, by way of example, several valves 23, 23a, 23b, 23c, 23d, 23e which are designed to be adjusted between an open state and a closed state and optionally also a partially open state. The valves 23 serve to control the flow of the circulating fluid F and / or the additional fluid FZ.

[0043] Fig. 2 shows an example of a partially depicted conveying container 4 with two screw conveyors 7. The screw conveyors 7 are arranged essentially parallel to each other and have a varying pitch. In an alternative embodiment of the conveying container 4, it can also contain only a single screw conveyor 7. In the illustrated example, the at least one screw conveyor 7 has three zones Z. A first zone ZI, in which the plastic material introduced into the conveying container 4 is transported away from the filling opening 5, extends from the filling opening 5 (not shown) a short distance towards the discharge opening 6. In the first zone ZI, the screw conveyor 7 preferably has a first pitch ST1. The pitch ST is understood to be the distance that the rotating helix of the screw conveyor 7 travels in a single revolution in the longitudinal direction of the screw conveyor 7.The first zone ZI is followed by a second zone Z2, in which the plastic material is compacted to prevent backflow of the liquid plastic material F and / or additional liquid FZ introduced into the conveying container 4 towards the filling opening 5. For this purpose, the screw conveyor 7 preferably has a second slope ST2 in the second zone Z2, which is smaller than the first slope ST1. The second zone Z2 is followed by a third zone Z3, in which the plastic material is mixed with the supplied circulating liquid F and / or additional liquid FZ. For this purpose, the return position PR and / or the feed position PE are located in the third zone Z3. Preferably, the screw conveyor 7 has a third slope ST3 in the third zone Z3, which is larger than the second slope ST2 to provide more space for the plastic material and for the circulating liquid F and / or additional liquid FZ.Thus, the plastic material in the third zone Z3 is less compacted than in the second zone Z2. In the example shown, the third zone Z3 extends to the discharge opening 6. The same effect as with changing the pitch can also be achieved by appropriately adjusting the distance between the screw flight and the inside of the conveying container (cylinder), or by a combination of these methods.

[0044] The circulating liquid F from the pyrolysis device 3 and / or the additional liquid FZ from the liquid container 15 can, for example, be pumped into the conveying container 4 at a pressure of 20 to 40 bar and a temperature between 200 and 350 °C.

[0045] The plastic material in the conveying vessel 4, viewed in the direction of flow upstream of the return position or the feed position, particularly in the second zone Z2, can, for example, have a pressure between 40 and 100 bar, a temperature between 30 and 170 °C, and a density between 0.9 and 1.1 kg / m³. Downstream of the return position or the feed position, the plastic material in the conveying vessel 4 can, for example, have a pressure between 20 and 40 bar, a temperature between 200 and 350 °C, and a density between 0.8 and 0.99 kg / m³.

[0046] Fig. 3 shows an exemplary flow diagram of the process for oiling plastics.

[0047] In step S 1, the previously described system 1 is provided.

[0048] In step S2, plastic material to be oiled is introduced through the filling opening 5 into the conveying container 4 of the conveying device 2.

[0049] In step S3, the plastic material introduced into the conveying container 4 is transported by at least one screw conveyor 7 of the conveying container 4 to the discharge opening 6 of the conveying container 4 and is compacted on the way to the discharge opening 6 at least in a section, such as the second zone Z2.

[0050] In an optional sub-step S3a, the plastic material received in the conveying container 4 is compacted more strongly between the return position PR and the filling opening 5 than between the return position PR and the discharge opening 6 and / or the plastic material received in the conveying container 4 is compacted more strongly between the feed position PE and the filling opening 5 than between the feed position PE and the discharge opening 6.

[0051] In step S4, the plastic material exiting the output opening 6 is fed to the pyrolysis device 3 and subjected to a pyrolysis process in the pyrolysis device 3. The pyrolysis process breaks down the plastic material, producing the cycle liquid F, which contains liquid plastic material and, if applicable, the additional liquid FZ.

[0052] In step S5, at least a portion of the circulating fluid F generated by the pyrolysis process is returned through the return line 10 to the conveying container 4 at the return position PR located between the filling opening 5 and the discharge opening 6. This preheats the newly introduced plastic material into the conveying container 4 with the heated circulating fluid F from the pyrolysis device 3 on its way to the discharge opening 6, preparing it for the subsequent pyrolysis process.

[0053] In an optional sub-step S5a, oil is returned to the conveying tank 4 as a recirculating liquid F produced by the pyrolysis process.

[0054] In an optional step S6, a first portion of the recirculated liquid F generated by the pyrolysis process is returned to the conveying container 4, and a second portion of the recirculated liquid F is added to the plastic material that has already emerged from the discharge opening 6. In an optional step S7, additional liquid FZ is taken from the liquid container 15 and introduced into the conveying container 4 at the feed point PE located between the filling opening 5 and the discharge opening 6, and / or added to the plastic material that has already emerged from the discharge opening 6.

[0055] In an optional sub-step S7a, oil is taken as additional fluid FZ from the fluid reservoir 15.

[0056] In an optional substep S7b, the feed-in position PE is provided at the same distance from the filling opening 5 as the return position PR, and in particular, the feed-in position PE is provided at the return position PR.

[0057] In an optional step S 8, the temperature at which the circulating liquid F generated by the pyrolysis process is returned to the conveying vessel 4 and / or the temperature at which the circulating liquid F generated by the pyrolysis process is added to the plastic material exiting the output opening 6 and / or the temperature at which the additional liquid FZ is introduced from the liquid container 15 into the conveying vessel 4 and / or the temperature at which the additional liquid FZ from the liquid container 15 is added to the plastic material exiting the output opening 6 is set such that it is lower than a pyrolysis temperature of the pyrolysis process but higher than the temperature of the plastic material at the associated feed position, return position or output opening and, in particular, higher than a melting temperature of the plastic material.

[0058] In an optional step S 9, the plastic material received in the conveying container 4 is at least partially melted by frictional energy introduced by the conveying device 2 and by the circulating liquid F generated by the pyrolysis process and / or by the additional liquid FZ taken from the liquid container 15.

Claims

Patent claims:

1. Method for oiling plastics, wherein the plastic material to be oiled is introduced through a filling opening (5) into a conveying container (4) of a conveying device (2), in the conveying container (4) by at least one conveying screw (7) is transported to a discharge opening (6) of the conveying container (4) and is thereby compressed, and the plastic material exiting the discharge opening (6) is fed to a pyrolysis device (3) in which the plastic material is subjected to a pyrolysis process, characterized in that a circulating fluid (F) containing liquid plastic material is generated by the pyrolysis process and at least a part of the circulating fluid (F) is returned to the conveying container (4) via a return line (10) at a return position (PR) provided between the filling opening (5) and the discharge opening (6).

2. Method according to claim 1, characterized in that the circulating fluid (F) comprises 5 wt% to 100 wt%, preferably 50 wt% to 95 wt%, in particular 70 wt% to 90 wt% liquid plastic material.

3. Method according to claim 1 or 2, characterized in that the circulating fluid (F) consists of liquid plastic material and an additional fluid (FZ), in particular a solvent.

4. Method according to one of claims 1 to 3, characterized in that only a part of the circulating liquid (F) produced by the pyrolysis process is returned as a first part to the conveying container (4) and a second part of the circulating liquid (F) is added to the plastic material that has emerged from the discharge opening (6).

5. Method according to any one of claims 1 to 4, characterized in that additional liquid (FZ), in particular a solvent, is taken from a liquid container (15) and applied to a surface between the filling opening (5) and the The plastic material is introduced into the conveying container (4) at the dispensing opening (6) and / or is added to the plastic material that has escaped from the dispensing opening (6).

6. Method according to any one of claims 1 to 5, characterized in that the circulating fluid (F) produced by the pyrolysis process is returned to the conveying container (4) at a temperature and / or added to the plastic material exiting the discharge opening (6) and / or the additional liquid (FZ) from the liquid container (15) is introduced into the conveying container (4) at a temperature and / or added to the plastic material exiting the discharge opening (6), which temperature is lower than a pyrolysis temperature of the pyrolysis process but higher than the temperature of the plastic material at the associated feed position (PE), return position (PR) or discharge opening (6) and in particular is higher than a melting temperature of the plastic material.

7. Method according to one of claims 1 to 6, characterized in that the plastic material received in the conveying container (4) is at least partially melted by frictional energy introduced by the conveying device (2) and by the circulating fluid (F) generated by the pyrolysis process and / or by the additional fluid (FZ) taken from the liquid container (15).

8. Method according to one of claims 1 to 7, characterized in that the plastic material received in the conveying container (4) is more densely compacted between the return position (PR) and the filling opening (5) than between the return position (PR) and the discharge opening (6) and / or the plastic material received in the conveying container (4) is more densely compacted between the feed position (PE) and the filling opening (5) than between the feed position (PE) and the discharge opening (6).

9. Method according to claim 5, 6 or 8, characterized in that the feed position (PE) is at the same distance from the filling opening (5) as the return position (PR) is provided and in particular the feed-in position (PE) is provided at the return position (PR).

10. Plant (1) for the oiling of plastics with a conveying device (2) for the plastics and a pyrolysis device (3) following the conveying device (2), wherein the conveying device (2) has a conveying container (4) with a filling opening (5) and a discharge opening (6) and with at least one conveying screw (7) arranged in the conveying container (49) between the filling opening (5) and the discharge opening (6), characterized in that a return inlet (8) of the conveying container (4) is connected at a return position (PR) provided between the filling opening (5) and the discharge opening (6) to a return line (10) leading from a liquid outlet (9) of the pyrolysis device (3) back to the conveying device (2), in which a circulating liquid (F) containing liquid plastic material from the pyrolysis device (3) is received.

11. Plant (1) according to claim 10, characterized in that a material inlet (13) of the pyrolysis device (3) connected to the dispensing opening (6) via a connecting line (12) is connected to the return line (10) and / or is connected to an additional return line (14) leading back from the liquid outlet (9) of the pyrolysis device (3), in which the circulating liquid (F) from the pyrolysis device (3) is recorded.

12. System (1) according to claim 10 or 11, characterized in that an outlet (16) of a liquid container (15) is connected to a liquid-conducting feed inlet (18) of the conveying container (4) is connected at a feed position (PE) provided between the filling opening (5) and the dispensing opening (6), wherein preferably the outlet (16) of the liquid container (15) is connected to the material inlet (13) of the pyrolysis device (3) via a liquid conductor.

13. Plant (1) according to one of claims 8 to 12, characterized in that the plastic material to be oiled is contained in the conveying container (4) and the circulating fluid (F) from the pyrolysis device (3) and / or the additional liquid (FZ) from the liquid container (15) at the associated feed position (PE), return position (PR) and / or a connection point (PV) with the connecting line (12) has a temperature below a pyrolysis temperature in the pyrolysis device (3) but above the temperature of the plastic material at the feed position (PE), return position (PR) and / or connection point (PV) with the connecting line (12) and in particular a temperature above a melting temperature of the plastic material.

14. Plant (1) according to one of claims 10 to 13, characterized in that the plastic material to be oiled is contained in the conveying container (4) and has a higher density between the return position (PR) and the filling opening (5) than between the return position (PR) and the discharge opening (6) and / or the plastic material to be oiled is contained in the conveying container (4) and has a higher density between the feed position (PE) and the filling opening (5) than between the feed position (PE) and the discharge opening (6).

15. Plant (1) according to one of claims 12 or 13, characterized in that the feed-in position (PE) is arranged at the same distance from the filling opening (5) as the return position (PR) and in particular the feed-in position (PE) is also the return position (PR) and the feed-in inlet (18) is also the return inlet (8).

Images