REACTOR ARRANGEMENT AND METHOD FOR DECOMPOSING OBJECTS CONSISTING OF PLASTIC-BASED COMPOSITE MATERIALS

Abstract

The invention relates to a reactor arrangement and to a method for decomposing objects of plastic-based composite materials into their individual constituents by way of a solvolysis using at least one reactor chamber in which the objects as exposed to a solvent in the supercritical state. The invention is characterized in that at least three pressure chambers located in series, a first load lock chamber, a reactor chamber adjoining the same, and a second load lock chamber adjoining the latter, which are each connected to each other via an actuatable partition which can be moved from an open position, in which two of the mutually adjacent pressure chambers are connected to each other, to a closed position, in which two of the mutually adjacent pressure chambers are fluidically, thermally and pressure-specifically isolated from each other. The reactor chamber is thermally coupled to a heating system and can be directly or indirectly fluidically connected via at least one first line to the first load lock chamber and can be connected to a first pressurizable feed line, via which solvent can be fed the reactor chamber.

Claims

1-18. (canceled)

19. A reactor arrangement for decomposing objects comprising plastic-based composite materials into individual constituents by performing solvolysis in at least one reactor chamber in which the objects are exposed to a solvent heated to a supercritical state, comprising: at least three pressure chambers positioned in series comprising a first load lock chamber, a reactor chamber adjoining the first load lock chamber, a second load lock chamber adjoining the reactor chamber which are connected together by actuatable partitions which are movable from an open position, in which two of the three adjacent pressure chambers are connected to each other, to a closed position, in which the two connected pressure chambers are fluidically, thermally and pressure isolatable from each other; the reactor chamber being thermally coupled to a heating system which is fluidically connectable by at least one first line to the first load lock chamber and is connected to a first pressurizable feed line through which solvent is fed into the reactor chamber; the second load lock chamber includes a second line which is connectable to the first load lock chamber; and means for transferring objects and a carrier for holding objects and objects being forced to transfer from one of the pressure chambers to an adjacent pressure chamber when one of the actuatable partitions is in an open position.

20. The reactor arrangement according to claim 19, wherein: the pressure chambers are each tubular, have an identical cross-sectional shape and size and each have a chamber longitudinal axes positioned coaxially to each other.

21. The reactor arrangement according to claim 19, wherein: the partitions include a slide valve.

22. The reactor arrangement according to claim 19, comprising: a check valve positioned in the first line.

23. The reactor arrangement according to claim 22, wherein: the check valve comprises an overpressure valve.

24. The reactor arrangement according to claim 19, comprising: a container positioned in the first line.

25. The reactor arrangement according to claim 19, wherein: the first load lock chamber is connectable to a second pressurizable feed line through which the solvent is fed into the first load lock chamber.

26. The reactor arrangement according to claim 19, comprising: a third feed line for feeding the solvent which opens into the second load lock chamber.

27. The reactor arrangement according to claim 26, comprising: at least one of a controllable feed pump and at least one flow valve are positioned in the first, second and third feed lines.

28. The reactor arrangement according to claim 19, comprising: a line connected to a collection container containing a check valve that opens into the second load lock chamber.

29. The reactor arrangement according to claim 19, comprising: means for a tilting the at least three pressure chambers from a horizontal position to a tilted position relative to the horizontal position so that the objects in the chamber slide under an effect of gravity out of one pressure chamber into a connected pressure chamber.

30. The reactor arrangement according to claim 19, comprising: an electromotively, hydraulically, pneumatically or magnetically assisted conveying mechanism for conveying the carrier along a longitudinal axis of the pressure chambers to two open pressure chambers.

31. The reactor arrangement according to claim 19, wherein: the first and second load lock chambers are closable to form a controllable fluid-tight and temperature controlled interior which is loadable and pressurizable at an end including an openable reactor cover.

32. A method for decomposing objects including plastic-based composite materials into individual constituents using a reactor arrangement according to claim 19, comprising steps of: a) charging the reactor chamber with a first carrier holding the objects and closing the reactor chamber; b) charging the first load lock chamber with a second carrier holding the objects and closing the first load lock chamber; c) feeding solvent into the reactor chamber and heating the reactor chamber to a temperature T1; d) limiting pressure in the reactor chamber to a first pressure by overpressure-regulated discharge of heated solvent from the reactor chamber to maintain the solvent in a subcritical state at the temperature T1 and a pressure P1; e) feeding the solvent discharged from the reactor chamber which is in the subcritical state into the first load lock chamber; f) increasing the pressure and temperature inside the reactor chamber to a temperature T2 and pressure P2, to cause the solvent to be at a supercritical state for a predefined process time t; g) transferring the first carrier holding the objects and the solvent out of the reactor chamber into the second load lock chamber after a processing time t is completed and discharging the solvent out of the second load lock chamber; h) transferring the second carrier holding the objects out of the first load lock chamber into the reactor chamber; i) charging the first load lock chamber using the first carrier holding the objects; j) removing the first carrier holding the objects from the second load lock chamber; and k) continuously carrying out method steps c) to j) so that further carriers holding objects are thermally treated to perform solvolysis in all of the pressure chambers.

33. The method according to claim 32, comprising: discharging the solvent in a subcritical state from the reactor chamber into a buffer storage; and feeding the subcritical solvent from the buffer storage into the first load lock chamber.

34. The method according to claim 32, wherein: in conjunction with step e), feeding solvent under pressure into the first load lock chamber.

35. The method according to claim 33, wherein: after the solvent has been discharged from the second load lock chamber after method step g) is performed, rinsing the second load lock chamber together with the carrier holding the objects present in the second load lock chamber with fresh solvent, and after the second load lock chamber has been rinsed, transferring the heated solvent from the buffer storage.

36. The method according to claim 32, wherein solvolysis is performed with water as a solvent which is used with process parameters of: T1=max. 320° C.; p1=max. 250 bar; T2=374° C. to 500° C.; and p2=230 bar to 250 bar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention is described below by way of example using exemplary embodiments and with reference to the drawings, without any limitation of the general inventive concept. In the figures:

[0035] FIG. 1 shows a p/T graph to explain a cyclic process for the solvolysis;

[0036] FIG. 2 shows an exemplary embodiment of a reactor arrangement formed according to the invention;

[0037] FIG. 3 shows a carrier with objects to be treated reactively arranged therein;

[0038] FIG. 4 shows an overview diagram; and

[0039] FIG. 5a-d show the individual process steps.

DETAILED DESCRIPTION OF THE INVENTION

[0040] FIG. 1 shows a thermodynamic pressure-temperature graph in which the phase transitions of water are shown as a function of pressure and temperature. In addition to the phase transitions which are known per se, the critical point for water should be noted. Upwards of a temperature of 374.12° C. and a pressure of 221.2 bar, there is no longer a defined state of matter for water, especially since the densities of the liquid and gas phases converge. It is precisely this critical point which must be reached and exceeded in order to achieve the desired effect of dissolving plastic-based fiber-reinforced composite materials.

[0041] The reactor arrangement according to the invention is assembled such that the thermodynamic cyclic process K shown in FIG. 1 can be implemented in the order of the cycle phases K1, K2, K3, K4 and K5 shown, with minimum energy input. Reference is made below to the cycle phases K1 to K5 shown in FIG. 1 in conjunction with the explanation of the method steps illustrated below.

[0042] FIG. 2 shows a preferred embodiment of the reactor arrangement according to the invention, which is formed by three pressure chambers connected to each other in series, to form a first load lock chamber 1, a reactor chamber 2 and a second load lock chamber 3. All three pressure chambers 1, 2, 3 function as hollow tubes each having the same inner diameter with the tube lengths of which being preferably selected to be equal. A first partition 4′ is introduced between the first load lock chamber 1 and the reactor chamber 2, and a second partition means 4″ is located between the reactor chamber 2 and the second load lock chamber 3. Each partition has a slide valve, which ensures free passage between the two mutually adjacent pressure chambers when in an open state and separates the mutually adjacent pressure chambers in a fluid-tight, thermally stable and pressure-stable manner from each other when in a closed state, at temperatures up to at most 650° and pressures or pressure differences up to 400 bar. The first and second load lock chambers 1, 3 can each be closed at the end with a reactor cover 5′, 5″, so that the first and second load lock chambers 1, 3 can be closed off in a fluid-tight manner from the environment.

[0043] The reactor chamber 2 is also equipped with a heating system H, with which it is possible to heat the reactor chamber 2 to a process temperature of up to 500° C.

[0044] Correspondingly adapted to the inner diameter of the otherwise equally dimensioned pressure chambers 1, 2, 3, a carrier 6 is provided (See FIG. 3), which is suitably designed to receive objects 7 to be chemically dissolved, which preferably are fiber-reinforced composite materials in the form of fragments or segments. To this end, the carrier preferably has grid-like holders 8, which allow flow and temperature distribution around the objects 7 on all sides as far as possible inside the carrier 6. Sliding elements 9 are attached to the outside of the carrier 6 to allow the carrier 6 to be slid or pushed easily through the tubular inner contour of the individual pressure chambers 1, 2, 3, which each have an identical cross-sectional shape and size and pressure chamber longitudinal axes which are oriented coaxially with each other. This ensures that a carrier 6 introduced into the reactor chamber 2 via the first load lock chamber 1 can easily pass into the reactor chamber 2 and from there into the second load lock chamber 3, from which the carrier 6 can be removed again from the reactor arrangement.

[0045] FIG. 4 shows a schematic overview of all the components necessary for operating the reactor arrangement according to the invention. The first load lock chamber 1 is closably openly connected via a first partition 4′ to the reactor chamber 2. The reactor chamber 2 is in turn closably openly connected to the second load lock chamber 3 with a second partition 4″ which is otherwise identical to the first partition 4′. The first and second load lock chambers 1, 3 can each be closed in a fluid-tight manner at the end with a reactor cover 5′, 5″. The reactor chamber 2 is thermally coupled to a heating system H, which is provided as the sole heat source inside the entire reactor arrangement according to the invention. A feed line Z1 opens into the first load lock chamber 1, via which feed line solvent, preferably in the form of water, can be fed by a feed pump F, preferably in a pressure-regulated and in a controlled manner and as required into the first load lock chamber 1.

[0046] Similarly, feed lines Z2, Z3 open into the reactor chamber 2 and the second load lock chamber 3, respectively, via which the feed lines are provided solvent in the form of water, can be fed by respective feed pumps F, preferably in a pressure-regulated manner, as required into the reactor chamber 2 and the second load lock chamber 3, respectively.

[0047] In addition, a first line A1 exits from the reactor chamber 2, along which is attached a controllable check valve SP. The first line A1 opens into a buffer store ZW, which is preferably thermally insulated, in order to store hot solvent discharged from the reactor chamber 2 in a controlled manner by use of the check valve SP temporarily for further use without the discharged solvent undergoing significant cooling. The buffer store ZW is connected to the first load lock chamber 1 via a feed line Z4 along which a check valve SP is likewise positioned. In addition, a second line A2, which is connected to the second load lock chamber 3 includes a controllable check valve SP opening into the buffer store ZW.

[0048] In addition, the reactor chamber 2 is fluidically connected to the first load lock chamber 1 via a third line A3. A controllable check valve SP is likewise positioned along the third line A3. Solvent passes via the third line A3 as required out of the reactor chamber 2 directly into the first load lock chamber 1 in order in this way to limit an overpressure building up in the reactor chamber 2 without at least one delay and assisting the preheating of the solvent in the first load lock chamber. In addition, the third line A3 allows controlled transfer of the solvent preheated in the first load lock chamber 1 into the emptied reactor chamber 2, as is explained in more detail below.

[0049] In the same way, a fourth line A4, along which a controllable check valve SP is likewise arranged, is attached between the reactor chamber 2 and the second load lock chamber 3. The fourth line A4 is used to control transfer the supercritical solvent out of the reactor chamber into the second load lock chamber 2, as is likewise explained in more detail below.

[0050] Finally, a fifth line A5, which is connected to a collection container AB which includes a check valve SP, exits from the second load lock chamber 3.

[0051] The above explained components interact to implement a process of decomposing objects of plastic-based composite materials in the following way:

[0052] Starting from a completely empty reactor arrangement as shown in FIG. 5a, a first carrier 61 is charged with objects to be treated reactively that are placed into the reactor chamber 2 via the first load lock chamber 1, which is open due to the open reactor cover 5′ and the partition means 4′, which has been positioned in the open position, between the first load lock chamber 1 and the reactor chamber 2. The partition 4′ between the first load lock chamber 1 and the reactor chamber 2 is then closed. A second carrier 62 provided with corresponding objects is introduced into the first load lock chamber 1 with the reactor cover 5′ open, and then the reactor cover 5′ is connected in a fluid-tight manner to the first load lock chamber 1. This situation is illustrated in FIG. 5a.

[0053] Water acting as a solvent passes via the feed line Z2 shown in FIG. 4 into the reactor chamber 2, wherein the feed pump F provided along the feed line Z2 can implement a water pressure of approximately 150 bar inside the reactor chamber 2. While the water solvent is being fed into the reactor chamber 2, the heating process with the heating system H begins. As a result, the temperature inside the reactor chamber rises to approximately 300° C.

[0054] The internal pressure inside the reactor chamber 2 is limited to at most 250 bar, for example in a pressure-regulated manner, by reducing the water quantity via the first line A1 and the controllable check valve SP provided along the first line A1. The heated solvent flowing out of the reactor chamber 2 via the first line A1 is collected in a buffer container ZW and temporarily stored as heated solvent. By further heating and pressure regulation inside the reactor chamber 2, the solvent is brought into the supercritical state, that is with temperatures of 380° C. to 400° C. and process pressures between 230 and 250 bar inside the reactor chamber 2. In this state, the objects are decomposed into their constituents by solvolysis. With reference to the thermodynamic cyclic process according to FIG. 1, this section of the process corresponds to cycle phase K3, which lasts until all the fiber constituents are separated out of the plastic-based matrix surrounding them. The cycle phase K3 of the solvolysis is typically approximately two hours.

[0055] In parallel with this, the thermally preheated and temporarily stored solvent is let out of the buffer store ZW and into the first load lock chamber 1. The first load lock chamber 1 is additionally filled with solvent by the feed unit F in order to reach a pressure of approximately 150 bar. The temperature inside the first load lock chamber is preheated by the solvent temporarily stored in the buffer store ZW and optionally via the third line A3 with the solvent originating from the reactor chamber 2 to a temperature of 300° C. and an internal pressure of at most 250 bar. The cycle phases K1 and K2 are thus implemented inside the first load lock chamber 1 while the cycle phase K3, in which the objects to be purified are decomposed into their constituents, is taking place in the reactor chamber 2. See FIG. 5b.

[0056] After the chemical decomposition process taking place in the reactor chamber 2 is complete, the solvent, which is in the supercritical state and contains the dissolved polymer portions, is discharged in a controlled manner into the second load lock chamber 3 via the fourth line A4. To this end, the check valve SP along the fourth line A4 is opened in a controlled manner. Owing to the expansion and pressure reduction which take place as the supercritical solvent passes into the second load lock chamber 3, the solvent immediately assumes a subcritical state. Then, the second partition means 4″ to the second load lock chamber 3 is opened, and the first carrier 61, charged with the chemically treated object residues, is transferred into the second load lock chamber 3.

[0057] To transfer the carrier 61 from the reactor chamber 2 into the second load lock chamber 3, a mechanism is provided which can transfer the carrier 61 in a force-assisted manner from the reactor chamber 2 into the second load lock chamber 3. The mechanism provided for this function can comprise an electromotive, hydraulic, pneumatic or magnetically assisted conveying mechanism, which conveys the carrier 61 in the longitudinal direction of the reactor chamber 2 and the second load lock chamber 3 connected openly to each other.

[0058] Alternatively, it is possible to tilt the entire reactor arrangement about the horizontal Ho, as illustrated in FIG. 5c, or even transfer it into the vertical. In this way, the carrier 61 situated in the reactor chamber 2 slides under the force of gravity into the second load lock chamber 3 when the second partition means 4″ is open. Using this gravity-driven conveying technology, the objects could also be introduced inside the pressure chambers without carriers, for example in the form of loose bulk material. In this case, the bulk material falls right into the following pressure chamber. The solvent flows in front in a controlled manner via the fourth, open line A4 out of the reactor chamber 2 into the second load lock chamber 3 and expands in the process. Then, the second partition 4″, closing the second load lock chamber 3, is transferred into the closed position, and the reactor chamber 2 is filled in a controlled manner with the preheated solvent from the first load lock chamber 1 via the open third line A3. The first partition 4′ between the first load lock chamber 1 and the reactor chamber 2 is then opened. In this way, the second carrier 62 situated in the first load lock chamber passes into the reactor chamber 2 into the first load lock chamber 1. After corresponding closing of the first partition means 4′ between the first load lock chamber 1 and the reactor chamber 2, the reactor arrangement is brought back into the original horizontal position Ho.

[0059] As a result of the rapid displacement of the first carrier 61 and the solvent out of the reactor chamber 2 into the right-hand load lock chamber 3 and as a result of the discharge of this solvent via the fifth line A5 into the collection container AB (See FIG. 4), a sudden drop in pressure and temperature takes place inside the second load lock chamber 3. This corresponds to the cycle phase K4 in the thermodynamic cyclic process K illustrated in FIG. 1. Then, the first carrier 61 introduced in the second load lock chamber 3 together with the fibrous object residual constituents are cooled by a fresh water rinse, which is implemented with the aid of the third feed line Z3 into the second load lock chamber 3. This cooling corresponds to the fifth cycle phase K5. The solvent introduced into the second load lock chamber 2 as a result of the fresh water rinse is preheated by thermal contact with the second load lock chamber 2 and the first carrier 61. As a result of which this solvent is transferred via the second line A2 into the buffer store ZW to fill the first load lock chamber 1, which is again charged with a third carrier 63 as shown in FIG. 5d with objects to be chemically treated.

[0060] After corresponding cooling and rinsing of the first carrier 61 situated in the second load lock chamber 3, the carrier can be removed from the second load lock chamber 3 after the reactor cover 5 has been opened. In this way, the insoluble object residues situated in the first carrier have undergone all the cycles of the solvolysis cycle shown in FIG. 1. At the same time, the subsequent solvolysis process corresponding to the third cycle phase K3 is already taking place inside the reactor chamber 2, the duration of the process of up to two hours corresponding to the time frames both for the dwell time of the objects inside the first load lock chamber 1, in which the cycle phases K1 and K2 take place, and the second load lock chamber 3, in which the cycle phases K4 and K5 take place as shown in FIG. 5d.

[0061] Thus, the reactor arrangement according to the invention can carry out the thermodynamic cyclic process K illustrated in FIG. 1 simultaneously, distributed between the first load lock chamber 1, the reactor chamber 2 and the second load lock chamber 3. In full-load operation, the process phases taking place in the individual pressure chambers change in a 2-hour rhythm.

[0062] In contrast to the three-chamber division illustrated, a first load lock chamber, reactor chamber, second load lock chamber, the reactor arrangement according to the invention can also be supplemented by further load lock chambers, in order to be able to implement the thermodynamic transitions with smaller differences in pressure and temperature. For example, two load lock chambers could be arranged in series upstream of the reactor chamber. Alternatively or in combination, two load lock chambers could also be arranged in series downstream of the reactor chamber.

LIST OF REFERENCE SIGNS

[0063] 1 First load lock chamber [0064] 2 Reactor chamber [0065] 3 Second load lock chamber [0066] 4′ First partition [0067] 4″ Second partition [0068] 5′, 5″ Reactor cover [0069] 6, 61, 62, 63 Carrier [0070] 7 Objects [0071] 8 Holder [0072] 9 Sliding element [0073] H Heating system [0074] K Thermodynamic cyclic process [0075] K1, K2, K3, K4, K5 Cycle phases [0076] A1, A2, A3, A4, A5 Line [0077] F Feed pump [0078] SP Check valve [0079] AB Collection container [0080] Z1, Z2, Z3, Z4 Feed line [0081] Ho Horizontal [0082] ZW Buffer container