WO2012072061A1 - Reactor and process for at least partially decomposing and/or cleaning plastic material - Google Patents

Abstract

Reactor for gasifying and/or cleaning, in particular for depolymerizing, plastic material (12), comprising a reactor tank (14) for receiving the plastic material (12), wherein the reactor tank comprises a metal melt, and a heating system (18) for heating the plastic material (12) in the reactor tank (14). According to the invention, a guide apparatus (24) which is arranged in an internal space (22) of the reactor tank (14) and is intended to guide liquefied plastic material (12) in the reactor tank (14) is provided, wherein the guide apparatus (24) is designed to guide the liquefied plastic material (12) on a helical path.

Description

 The invention relates to a reactor for gasifying and / or purifying according to the preamble of claim 1. According to a second aspect, the invention relates to a method for at least partial decomposition, in particular for depolymerization, and / or cleaning plastic material.

At present, used plastic products are usually recycled material that they are processed into products in which the plastic quality plays a minor role, for example, benches or piles. However, these applications are unable to absorb the immense amounts of plastic waste, so much of the plastic waste is used as fuel.

From US 5,436,210 A a generic device for treating waste is known in which the waste is introduced from below into a bath of liquid metal. The waste decomposes and leaves the bath liquid or in gaseous form.

From EP 1 840 191 A1 a device for gasification of biomass is known. As a rule, such a reactor is not suitable for gasifying or cleaning plastic material, since the underlying chemical processes are different.

CONFIRMATION COPY From JP 2004 256 773 A, a thermal decomposition device is known, in which the material to be pyrolyzed is guided in a horizontally extending tube, which is heated from the outside. In order to remove residues, the decomposition device has a rotating screw, by means of which the residues are conveyed to a pipe end in order to extract them there.

The invention has for its object to propose a reactor for gasification and / or cleaning of plastic material, which manages with a small space.

The invention solves the problem by a generic reactor in which the guide device is designed to conduct the liquefied plastic material on a helical path.

According to a second aspect, the invention solves the problem by a method for at least partially decomposing, in particular depolymerizing, and / or purifying plastic material, comprising the steps of: (a) introducing the plastic material into a reactor vessel extending along a longitudinal axis, (B) heating the plastic material by means of a heater and (c) by means of a arranged in the interior of the reactor vessel guide device of the plastic material on a path around the longitudinal axis of the reactor vessel around.

An advantage of the invention is that the plastic material in the reactor covers a long way, so that it reacts chemically to a large extent. By directing the plastic material on the helical path, the reactor can be made very compact, which reduces the heat losses through radiation.

In the context of the present description, the term especially a thermocatalytic depolymerization understood. This is understood to mean a reactor which is designed to thermally and / or catalytically depolymerize supplied polymers and / or to decompose them into substances having a lower melting or boiling point. However, the reactor can also be designed to clean plastic material. The temperature in the reactor is then preferably chosen so that the contaminant decomposes, but the plastic material remains unaffected. Under the heater is any device to understand that is designed to supply heat energy to the plastic material in the reactor vessel. Preferably, it is an inductive heating, which generates inductive heat at least in parts of the reactor vessel and / or arranged in the interior of the reactor vessel components. This has the advantage that even radially inner parts of the reactor vessel can be heated well.

In particular, the guiding device is understood to mean a structure which is designed in such a way that each imaginary volume element of the plastic material has to circumnavigate the longitudinal axis at least once. Of course, this only applies to the non-gas converted components of the imaginary volume element. In particular, the guide device is formed flat. For example, the guide device is made of a metal sheet. By the feature that the guide device is designed to conduct the liquefied plastic material on a helical path, it is understood, in particular, that the guide device is designed to force the liquefied plastic material onto a path that is at least twice, but more particularly around the longitudinal axis of the reactor vessel. It is possible, but not necessary, for the reactor device to be helical. It is also possible, for example, for the guide device to consist of a plurality of sheets, which are cut off in sections. se substantially horizontally and extend in sections obliquely upward. In this case, the plastic material flows on a path which only extends in sections upwards and in sections substantially horizontally.

Preferably, the reactor has a feeding device for feeding plastic material. This feed device is preferably arranged near the bottom of the reactor vessel. It may comprise an extruder by means of which plastic material can be plasticized.

According to the invention, the reactor vessel comprises a molten metal. The molten metal may comprise, for example, a Wood's alloy. In general, it is advantageous if the molten metal has a melting point of at most 300 ° C.

It is advantageous if the reactor comprises a condenser, by means of which gases are condensable, leaving the reactor vessel. Such gases are usually decomposition products of the plastic material. It is advantageous if the reactor vessel comprises plastic material in the form of polyolefin, which is introduced, for example via the metering device from below into the reactor vessel. When polyolefin decomposes, a petroleum-like liquid is formed which can be burned for heating purposes or available for synthesis. According to a preferred embodiment, the guide device extends with respect to a vertical cross section with increasing radial distance upwards. In other words, the guide device is then designed so that plastic material striking the guide device is conducted upwards and radially outwards. In this case, gas which has formed as a result of the decomposition of the plastic material accumulates, preferably at the radially outer edge of the guide device. Alternatively, it is possible that the guide device extends horizontally with respect to a vertical cross section or extends downward with increasing radial distance. In this case, it is advantageous if the reactor has a central column, so that inwardly directed plastic material can not flow over the radially inner edge of the guide and can rise directly upwards.

It is also possible for the guide device to extend horizontally in sections with respect to a vertical cross-section, to extend in sections at decreasing radial distance upwards and / or to extend in sections as the radial distance increases. In this way, the flow of the resulting gas can be influenced as desired. According to a preferred embodiment, the guide device is at least partially constructed of ferromagnetic material. This is particularly favorable when the heater is an inductive heater. The guide device is then heated by the electromagnetic alternating field emitted by the inductive heating, so that the temperature in the immediate vicinity of the guide device is particularly high. It is favorable if the thickness of the guide device amounts to at least 1 millimeter, in order to ensure on the one hand a sufficient mechanical stability and on the other hand to achieve a good coupling to the inductive alternating field.

Preferably, the guide device from bottom to top through recesses. These recesses may be holes, slots or gaps between the recess and, for example, an inner side of the reactor vessel.

It is favorable if the recesses are arranged at least marginally, in particular radially outside and / or radially inside. It is there- at low, if the recesses have a small cross-section or a small clear width. As a result, a particularly high flow resistance is opposed to liquid plastic material. According to a preferred embodiment, the guide device has a thickening adjacent to at least a part of the recesses. This is to be understood that the guide device is formed so that a surface facing the recess is greater than a thickness of the guide would be without this thickening in the same place. In particular, this thickening is constructed of ferroelectric iron material. For example, the guide device may comprise a sheet metal, in which the recesses are introduced. Adjacent to the recesses can then be welded, for example, thickening elements. To improve the coupling to a changing magnetic field, it can preferably be provided that the reactor vessel comprises or is constructed of ferroelectric material, at least on its side facing the interior. It is also beneficial if the reactor has in its interior heating elements, which may have ferroelectric material. These heating elements may, for example, be balls. In general, it is favorable if the heating elements are convex, with an imaginary envelope ball of minimum diameter surrounding the heating element, in particular a diameter of at most 50 millimeters. It is also beneficial if this envelope ball diameter is at least 3 millimeters. In the following the invention will be explained in more detail with reference to the accompanying drawings. It shows

1 shows a reactor according to the invention for carrying out a method according to the invention.

FIG. 1 shows a reactor 10 according to the invention for gasifying plastic material 12, in particular polyolefin polymers. The reactor comprises a reactor vessel 14 for heating the plastic material 12, which is introduced via an extruder 16, for example, on the bottom side into the reactor vessel 14.

The reactor 10 comprises a heater 18 in the form of an inductive heater, which has a plurality of coils 20.1, 20.2, 20.5, by means of which an alternating magnetic field is generated in an interior 22 of the reactor vessel 14. The coils 20 (reference numerals without counting suffix denote the object as such) are connected to a not shown power supply unit which applies an alternating current to the coils. The frequency of the alternating current is, for example, in the range of 25 to 50 kHz. Higher frequencies are possible, but lead to an increase in the so-called skin effect, which is undesirable.

In the interior 22 of the reactor vessel 14, a guide device 24 is arranged, by means of the plastic material 12 is guided on a helical path about a longitudinal axis L of the reactor vessel 14. The guide device is formed in the present case as a screw.

The reactor vessel 14 is filled with a molten metal 26 having a melting point of at most Ts _C hmeiz = 300 ° C. For example, the molten metal consists of Wood's metal. The molten metal usually has a density of more than 9 grams per cubic centimeter, so that the plastic material 12 experiences a buoyancy and from below to the Guide device 24 is pressed.

Due to the temperature T in the reactor vessel 14, the plastic material 12 decomposes successively, thereby forming gas bubbles 28.1, 28.2, .... The molten metal 26 may have a katalyttsche effect on the decomposition process, so that it is in the reactor 10 to a thermokata - lytic depolymerization reactor can act. In particular, the plastic material is polyolefin, which depolymerizes under the influence of temperature, so that the gas bubbles 28 may contain, inter alia, alkanes, alkenes and alkynes.

Due to the helical shape of the guide device 24, the plastic material 12 moves on its way from an inlet opening 30, which is preferably arranged at the bottom of the reactor vessel 14, on a helical path, that is on a wound around the longitudinal axis L web upwards. A flow direction of the flow of plastic material 12 is therefore upward in vectorial notation and has a strong peripheral component that is greater than a radial component. FIG. 1 shows the reactor 10 in a vertical cross section. It can be seen that the guide device 24 is directed with respect to this cross section with an increasing radial distance r from the longitudinal axis L downwards. As a result, plastic material 12 striking the guide device 24 is directed radially inward. In particular, the gas bubbles 28 move radially inward where they meet a column 32. The guide device 24 comprises a plurality of recesses 34.1, 34.2, through which gas can easily escape upwards.

As the drawing in Figure 1 shows, are just to the recesses 34, for example, the recess 34.3, thickenings 36.1, 36.2, arranged, which are realized in the present case by welded iron rods. Since iron is ferromagnetic material, the verdigris heat up. Cusions 36 and a passing through the recess 34.3 gas bubble 28.3 is heated as well as any permeating plastic material. The thickening 36 thus has the effect that one of the recess 34.3 facing surface A is greater than an area A \ the recess 34.3 would face, if the thickening 36 were not present. In other words, the thickening 36 leads to an increase in the local thickness D.

FIG. 1 schematically shows that a recess 34.4 in the form of a continuous slot can be formed on a radially inner inner edge 38 of the guide device 24. Since the highest point is in each case radially inward with respect to a screw turn, gas can be removed upwards in a particularly efficient manner through this radially inner recess.

The reactor vessel 14 is constructed on its side facing the interior 22 of a ferromagnetic material, for example of iron or magnetic steel. Furthermore, the guide device 24 is made of ferromagnetic material, so that they are heated by the induction heating 18. The induction heater 18 is designed so that a temperature gradient results, with the temperature increasing with increasing height. At the lower end of the reactor vessel 14, the temperature is usually ungührt T = 300 ° C, whereas it is at the upper region at about T = 450 ° C.

The reactor 10 has a pollutant discharge 40, which is arranged at the upper end of the reactor vessel 14. Since typical contaminants of plastic material, such as sand, are lighter than the metal bath, they float up and can be pulled off at the top. The reactor 10 also includes a gas vent 42, which opens into a condenser 44 and withdraws the gas produced. Liquid material leaving the condenser 44 enters a collector 46. An inventive method is carried out in that by means of the extruder 16, the plastic material 12 is preheated to about 250 ° C. Thereafter, the partially plasticized plastic material 12 is introduced via the inlet opening 30 into the reactor vessel 14 and heated there. The plastic material 12 runs helically in the reactor vessel 14 upwards and is gasified. As the plastic material, polyolefin is preferably used. However, other polymers can also be used. It is favorable if it concerns anthropogenic plastics, in particular substantially anhydrous plastic materials. Due to charring tendency, the reactor 10 is generally unsuitable for the conversion of organic material.

If the plastic material 12 to be cleaned, the metal bath 26 is brought to a temperature at which the plastic material 12 does not decompose, but the impurities contained.

LIST OF REFERENCE NUMBERS

0 reactor L longitudinal axis

2 plastic material T temperature

4 Reactor vessel T _Sc me mt Melting temperature6 Extruder r Radial distance8 Heating

 A area

0 coil D thickness

2 interior

4 guiding device

6 molten metal

8 gas bubbles 0 inlet

2 pillar

4 recess

6 thickening

8 inner edge 0 pollution discharge

2 gas vent

4 capacitor

6 collectors

Claims

claims: 1. reactor for gasifying and / or cleaning, in particular for depolymerizing Sieren of plastic material (12), with  (a) a reactor vessel (14) for receiving the plastic material (12),  (b) wherein the reactor vessel comprises a molten metal,  (C) a heater (18) for heating the plastic material (12) in the reactor vessel (14)  marked by  (D) a in an interior space (22) of the reactor vessel (14) arranged guide device (24) for conducting liquefied plastic materials (12) in the reactor vessel (14),  (e) wherein the guide means (24) is adapted to direct the liquefied plastic material (12) on a helical path. 2. Reactor according to claim 1, characterized in that the guide device (24) is helical. 3. Reactor according to one of the preceding claims, characterized in that the guide device (24) with respect to a vertical cross-section with increasing radial distance (r) directed upward, so that on the guide device (24) incident liquefied plastic material (12) radially is directed outside. 4. Reactor according to one of the preceding claims, characterized in that the guide device (24) is at least partially constructed of ferromagnetic material. 5. Reactor according to one of the preceding claims, characterized in that the guide device (24) from bottom to top through recesses (34). 6. Reactor according to one of the preceding claims, characterized in that the guide device (24) adjacent to at least one recess has a thickening (36). 7. Reactor according to one of the preceding claims, characterized in that the reactor vessel (14) at least on its interior (22) facing side comprises ferroelectric material. 8. Reactor according to one of the preceding claims, characterized in that it comprises in its interior (22) heating elements having ferromagnetic material. 9. A method for at least partially decomposing, in particular for depolymerizing, and / or cleaning plastic material (12), characterized by the steps:  (a) introducing the plastic material (12) into a reactor vessel (14) extending along a longitudinal axis (L) and comprising a molten metal,  (b) heating the plastic material (12) by means of a heater (18), (c) by means of a guide device (24) arranged in an interior space (22) of the reactor vessel (14) guiding the plastic material (12) on a path around the longitudinal axis (L) of the reactor vessel (14). 10. The method according to claim 9, characterized in that the plastic material (12) consists predominantly of at 23 "C solid polyolefin.