DE102012008457B4 - Reactor for gasifying and / or purifying, in particular for depolymerizing plastic material, and associated method - Google Patents

Abstract

Reactor for gasifying and / or cleaning, in particular for depolymerizing plastic material (12), with
(a) a reactor vessel (14) for receiving a starting material (12), in particular the plastic material (12),
(b) a metal bath (26)
- In the reactor vessel (14) is arranged and
Comprises a liquid metallic substance having a metal bath melting temperature (T _enamel ),
(c) a plurality of filling elements (25) in the metal bath (26),
(D) a heater (18) for heating the plastic material (12) in the reactor vessel (14) and
(e) a residue removal device for at least partially removing residues (38) which arise during the gasification and / or purification of the starting material (12),
characterized in that
(F) the residue removal device comprises a centrally arranged in the reactor vessel (14) overflow, so that on the metal bath (26) floating residues (38) are removable through the overflow.

Description

The invention relates to a reactor for gasifying and / or purifying, in particular for depolymerizing plastic material, with (a) a reactor vessel for receiving a starting material, in particular the plastic material, (b) a metal bath which is arranged in the reactor vessel and comprises a liquid metallic substance having a molten metal bath temperature, (c) a heater for heating the plastic material in the reactor vessel, and (d) a residue removal device for at least partially removing residuals resulting from gasification and / or purification of the feedstock.

Such a reactor is from the WO 2010/130 404 A1 and is used to gasify plastics, especially polymers. For this purpose, the plastic is introduced, for example, by extruder in the reactor vessel of the reactor, where it comes into contact with a metal bath. The high temperatures and the optionally present catalytic effect of the metal bath lead to the depolymerization of the plastic.

The starting material may comprise substances which are either completely inert or do not completely gas so as to leave residuals. These residues must be removed from the reactor vessel, so that it is continuously operable. It has been found that the removal of the residues is a limiting factor in terms of the economic operability of the reactor.

The DE 197 35 153 A1 describes a method and an apparatus for the gasification of waste materials. In this case, the starting material to be gasified is preferably introduced into a heated reactor already filled with liquid slag in such a way that the slag is set in rotation by a momentum transfer. The organic constituents of the starting material are gasified and the mineral constituents are melted and absorbed by the slag. This leads to an increase in volume of the slag. If the slag volume exceeds a certain limit, a portion of the slag passes through a lateral opening of a centrally mounted in the reactor tube in a water bath, where it solidifies.

The DE 196 29 544 C2 discloses a process for the preparation of polyvinylchloride. Again, the PVC is placed in a rotating slag bath in which a gaseous part is split off and the remainder of the slag is absorbed. Again, the resulting slag is passed through a central drain in a water bath.

The invention is based, to improve the removal of the residues from the reactor vessel the task.

The invention solves the problem by a generic reactor in which the residue removal device comprises a centrally disposed in the reactor overflow, so that floating on the metal bath residues are removable through the overflow. According to a second aspect, the invention solves the problem by a method of operating such a reactor, comprising the steps of: (i) raising a level of the metal bath so that residues enter the overflow, and (ii) removing the residues through the reactor overflow.

It has been found that a centrally arranged overflow is particularly suitable for effectively removing the residues from the reactor vessel. So it is an advantage that the overflow always has the same temperature as the surrounding metal bath. It is therefore impossible that the residues cool off when peeled off and thereby stick together.

It is a further advantage that the gas evolution during operation of the reactor promotes the removal of the residues. It has surprisingly been found that the gas evolution at the radially outer edge of the interior of the reactor vessel is particularly large. The rising there gas bubbles raise the level of the metal bath on average over time, so that floating on the metal bath residues undergo a force radially inward. This results in a residual flow radially inward, which can be derived by the centrally arranged overflow particularly effective.

The surprising finding that the residues have a preferred flow direction, namely radially inward, also leads to the fact that all residues reach the overflow after a relatively short time. If the overflow was arranged radially on the outside, areas can arise on the surface of the metal bath in which the residence time of the residues is so high that the residues form lumps and in the end are difficult to remove from the reactor vessel.

Although the central arrangement of the overflow has the disadvantage that a direct action from outside, for example, to remove bonded residues, is more difficult, but this disadvantage is more than offset by the described advantages.

Under the reactor vessel is understood in particular a device which in operation the Metal bath, the filling elements and the starting material absorbs.

The metal bath is understood to mean a collection of liquid metal, in particular a molten metal, which is liquid at an operating temperature of the reactor.

In particular, the metal bath consists of Wood's metal, the Lipowitz alloy, the Newton alloy, the Lichtenberg alloy and / or an alloy comprising gallium and indium. The metal bath usually has a density of more than 9 grams per cubic centimeter, so that the starting material undergoes a strong buoyancy. A melting temperature of the metallic substance is in particular at least 300 ° C. Lower melting temperatures are possible. Preferably, the melting temperature is at most 600 ° C. When operating the reactor, the metal bath has a temperature T of 300 ° C to 600 ° C.

According to a preferred embodiment, the overflow is formed by a removal tube which is in thermal contact with the metal bath. In this way, the sampling tube always has the same temperature as the metal bath, so that a clumping caused by cooling of the residues is avoided. Preferably, the sampling tube is a metal tube, in particular a ferromagnetic metal tube.

The heating is understood in particular to mean a device by means of which the plastic material can be heated directly or indirectly. In particular, the heater is an induction heater, by means of which a component of the reactor is heated. For example, the filling elements are ferromagnetic, so that they can be heated by induction. However, it is also conceivable that the overflow and / or the reactor vessel are ferromagnetic in addition or alternatively to the filling elements.

The starting material is heated in particular by heating the filling elements, which in turn heat the metal bath. The metal bath then transfers the heat to the starting material.

The residue removal device is in particular a device by means of which solid, viscous and / or pasty solids produced during gasification and / or cleaning can be withdrawn.

According to a preferred embodiment, a residue-conveying device is arranged in the removal tube, which is designed for conveying residue by mechanical action. For example, it is a screw conveyor that can scrape the inside of the sampling tube to prevent or eliminate clogging.

Preferably, the sampling tube has a tube inside diameter having at least one-tenth of a reactor vessel internal diameter of the reactor vessel. In this way, the residue can be removed efficiently.

It is advantageous if the residue removal device comprises a storage container and a gas-tight lock, so that the storage container is gas-tight from the reactor vessel can be separated. In other words, it is possible to separate the storage container from the reactor vessel, without the gas can penetrate into the reactor vessel and without the gas can escape from the storage container. In this way, the risk of fire is reduced, since otherwise flammable gases can escape.

In the following the invention will be explained in more detail with reference to the accompanying drawing. It shows

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

1 shows a reactor 10 for gasifying starting material in the form of plastic material 12 , in particular of polyolefin polymers. The reactor comprises, for example, a substantially cylindrical reactor vessel 14 for heating the plastic material 12 that's about an extruder 16 in the reactor vessel 14 is introduced.

The reactor 10 includes a heater, such as an induction heater 18 which have a plurality of coils 20.1 . 20.2 , ..., 20.4 by means of which an alternating magnetic field in an interior space 22 of the reactor vessel 14 is produced. The spools 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 f of the alternating current is for example in the range of 4 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 is a braking device 24 arranged, by means of the stream of liquefied plastic material 12 up in the reactor vessel 14 can be slowed down. The brake device 24 includes a variety of in the interior 22 movably arranged filling elements 25.1 . 25.2 , ... of ferromagnetic material, which are formed in the present case by balls with a spherical radius R. The spherical radius R can be, for example, between 0.5 and 50 millimeters.

Due to their ferromagnetic properties, the filling elements 25 through the induction heating 18 heats and warms one in the reactor vessel 14 existing molten metal 26 , Specifying that an object is like the filler elements 25 are formed of ferromagnetic material, always means that the object is ferromagnetic at room temperature of 23 ° C.

The filling elements 25 have a Curie temperature T _{C, 25} , above which the magnetic susceptibility χ abruptly decreases. The coupling to the radiated from the induction heating electromagnetic field is thus suddenly smaller and the heat output of the filling elements 25 drops sharply. The heat input by the induction heating is thus lower in the hot filling elements than in cold filling elements.

The molten metal 26 has a melting point of T _melt = 300 ° C and is up to a level H _filling in the reactor vessel 14 filled. It fills together with the plastic material, the spaces between the filling elements 25 , For example, the molten metal exists 26 made of Wood's metal, the Lipowitz alloy, the Newton alloy, the Lichtenberg alloy and / or an alloy comprising gallium and indium. The molten metal 26 usually has a density of at least 9 grams per cubic centimeter, leaving the plastic material 12 experiences a strong buoyancy. This buoyancy turns the plastic material 12 accelerated. The filling elements 25 counteract this acceleration.

In the reactor vessel 14 There is a temperature T, which is above a reaction temperature T _R , at which the plastic material 12 gradually decomposed. Gas bubbles are formed 28 that rise to the top. The molten metal 26 may have a catalytic effect on the decomposition process, so that it is in the reactor 10 may be a thermo-catalytic depolymerization reactor. That through the extruder 16 supplied plastic material 12 passes through an inlet opening 30 preferably at the bottom of the reactor vessel 14 is arranged in the interior 22 ,

The brake device 24 For example, restraint devices such as frames may include strained meshes whose meshes are so small that the filler elements 25 can not pass up. That is not necessary. For example, a ball fill as shown here is sufficient. The distribution of filling elements 25 , in the present case of bullets, is in 1 drawn purely schematically.

Due to their buoyancy, a part of the filling elements floats 25 on the molten metal 26 and another part is from higher-level filler elements 25 into the molten metal 26 pressed. The filling elements 25 are in 1 also drawn in a constant radius R. It is possible that the filling elements have variable radii, wherein the radius R decreases, for example, towards the top.

1 also shows a centric in the reactor vessel 14 arranged extraction pipe 36 , by the floating on the metal bath residues 38 are removable. The sampling tube 36 runs in the present case coaxially to a longitudinal axis L of the reactor vessel 14 , The residues 38 are for example impurities of the plastic material 12 and / or optionally added catalyst 32 that by the extruder 16 or an optionally present second extruder can be supplied.

The sampling tube 36 may consist of ferromagnetic tubing having a tubing Curie temperature T _{C, 36} . This heats the sampling tube 36 on T _{C, 36} on when the induction heating 18 operated with sufficiently high power. The tube material Curie temperature T _{C, 36} may for example correspond to the filling element Curie temperature T _{C, 25, 1} , but it may also be smaller or larger. But it is also possible that the sampling tube 36 is constructed of a non-ferromagnetic material, such as austenitic steel or titanium.

The reactor vessel 14 is at least on its interior 22 facing side constructed of a wall material. The wall material may be ferromagnetic, for example iron or magnetic steel. Alternatively, the wall material may also be non-magnetic.

If the wall material is ferromagnetic, then it has a wall material Curie temperature T _{C, 14} . This may be smaller than the filling element Curie temperature T _{C, 25} . In this case, the wall of the reactor vessel 14 colder than the filling elements during operation 25 ,

The sampling tube 36 is part of a pollution discharge 40 , Because typical impurities 38 of plastic material, for example sand, have a lower density than the metal bath 26 , they float up and can be pulled up. The pollution discharge 40 also includes a storage container, which also serves as a settling tank 48 may be referred to, in which accumulates residue. The residue 38 may not contain completely depolymerized organic material in addition to inorganic material. The organic material floats on the inorganic material and can pass through a recycling line 50 bottom side in the reactor vessel 14 to be led back.

The reactor 10 also includes a gas vent 42 into a capacitor 44 discharges and gas emerging. From the condenser 44 escaping liquid material enters a collector 46 ,

The reactor described can be operated as a starting material instead of plastic material, for example, with waste oil and then serve the treatment.

A method _{according to the} invention is carried out by first raising the level _Hfüll , for example by the fact that the reactor vessel 14 metal 26 is supplied. This can be done by solid metal balls of the metallic material in the reactor vessel 14 be introduced so that they melt. It is also possible that the influx of plastic material 12 is increased, in particular by the fact that the extruder is operated at a higher power. This increases in the reactor vessel 14 existing volume of both gasified and non-gassed plastic material, so that the level H increases _filling , for example in the form of the sampling _tube 36 , The residues 38 are then withdrawn, that is, they either flow automatically through the sampling tube or that they by a corresponding device through the sampling device, in the present case through the sampling tube 36 be conveyed through.

It may be advantageous to reduce the supply of plastic material prior to increasing the metal level to reduce the formation of gas bubbles. This has the advantage that fewer gas bubbles are formed, thereby reducing spray losses of metal bath.

Preferably, the level is lowered again after raising the level of the metal bath and removing the residues through the overflow, for example by draining metal bath.

It is favorable if a level of the metal bath is adjusted such that a layer thickness H _{38 of} the residual material layer of at least 10 cm is established, whereby this layer thickness H ₃₈ can be undershot if the level of the metal bath for removing the residues is raised by the overflow ,

In other words, the feature that the layer thickness H _{38 of} the residual material layer is at least 10 cm is understood to mean that at least 75% of the time, this layer thickness H _{38 is} reached and exceeded. The layer thickness H ₃₈ is measured from the boundary layer between metal bath and residue layer on the one hand and the top edge of the residue layer on the other. Preferably, the layer thickness is regulated. That means the reactor 10 a non-illustrated layer thickness detection device, by means of which the layer thickness H ₃₈ can be detected. If a maximum layer thickness H _{38, max is} exceeded, then the method described above for removing the residues is carried out.

LIST OF REFERENCE NUMBERS

10

reactor

12

Plastic material

14

reactor vessel

16

extruder

18

induction heating

20

Kitchen sink

22

inner space

24

braking device

25

infill

26

metal

28

gas bubble

30

inlet opening

32

catalyst

34

outer wall

36

sampling tube

38

waste material

40

pollution removal

42

gas vent

44

capacitor

46

collector

48

Absetzbehälter

50

recycle line

χ

magnetic susceptibility

f

frequency

L

longitudinal axis

R

spherical radius

H _fill

Level, level

H ₃₈

layer thickness

d ₁₄

Reactor vessel inner diameter

d ₃₆

Pipe internal diameter

T _enamel

Metal-melting temperature

T

temperature

T _R

reaction temperature

T _{C, 36}

Pipe material Curie temperature

T _{C, 25}

Filler Curie temperature

T _{C, 14}

Wall material Curie temperature

Claims (7)

Reactor for gasifying and / or purifying, in particular for depolymerizing plastic material ( 12 ), with (a) a reactor vessel ( 14 ) for receiving a starting material ( 12 ), in particular of the plastic material ( 12 ), (b) a metal bath ( 26 ), which - in the reactor vessel ( 14 ) and comprises a liquid metallic substance having a metal bath melting temperature (T _enamel ), (c) a plurality of filling elements ( 25 ) in a metal bath ( 26 ), (d) a heater ( 18 ) for heating the plastic material ( 12 ) in the reactor vessel ( 14 ) and (e) a residue removal device for the at least partial removal of residues ( 38 ) used in the gasification and / or purification of the starting material ( 12 ), characterized in that (f) the residue removal device has a centric position in the reactor vessel ( 14 ) arranged overflow, so that on the metal bath ( 26 ) floating residues ( 38 ) are removable through the overflow. Reactor according to claim 1, characterized in that the overflow through a withdrawal pipe ( 36 ) which is in thermal contact with the metal bath ( 26 ) stands. Reactor according to claim 2, characterized in that in the withdrawal tube ( 36 ) A residue-conveying device is arranged, which is designed for conveying residue by mechanical action. Reactor according to one of claims 2 or 3, characterized in that the withdrawal tube ( 36 ) has a tube internal diameter (d ₃₆ ) which is at least one tenth of a reactor vessel internal diameter (d ₁₄ ) of the reactor vessel ( 14 ) Has. Reactor according to one of the preceding claims, characterized in that the residue removal device comprises a storage container ( 48 ) and a gas-tight lock, so that the storage container ( 48 ) is removable gas-tight. Method for operating a reactor ( 10 ) for gasifying and / or purifying, in particular depolymerizing, plastic material ( 12 ) containing (a) a reactor vessel ( 14 ) for receiving the plastic material ( 12 ), (b) a metal bath ( 26 ), which - in the reactor vessel ( 14 ) and - comprises a liquid metallic substance having a metal bath melting temperature (T _enamel ), (c) a heating ( 18 ) for heating the plastic material ( 12 ) in the reactor vessel ( 14 ), and (d) a residue removal device for at least partial removal of residues ( 38 ) used during gasification and / or cleaning of the plastic material ( 12 ), which centrically in the reactor vessel ( 14 ) arranged overflow, so that on the metal bath ( 26 ) floating residues ( 38 ) are removable by the overflow, comprising the steps of: (i) raising a level of the metal bath ( 26 ), so that residues ( 38 ) in the overflow ( 36 ), and (ii) stripping off the residues ( 38 ) through the overflow ( 36 ). Method according to claim 6, characterized by the steps of: - supplying plastic material ( 12 ) to the reactor vessel ( 14 ), Wherein the feeding of the plastic material ( 12 ) to the reactor vessel ( 14 ) and / or adjusting the level of the metal bath ( 26 ) is carried out so that on the metal bath ( 26 ) a residue layer of residues ( 38 ), - wherein a layer thickness (H ₃₈ ) of the residue layer is at least 10 centimeters.

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