System for producing recycled polyurethane foam

Abstract

System for the production of recycled polyurethane foam (100), which contains: a miller (1), which has an input (2a) and an output (2b) and in the space of the miller there are one or more elements arranged for chopping, which are optionally tempered rotating blades located on a rotor and fixed counter-blades; a rotating drum powder separator (3) is positioned compared to the outlet (2b) of the miller in such a way that its inlet hopper (4a) is positioned so that the PU foam chips are fed into the rotating drum powder separator (3) by gravity; two or more conveyor belts (10, 11, 12) that link said rotating drum powder separator (3) with a press collection crate ( 13 ); one or more magnets that are positioned after the first conveyor belt (10) between the rotating drum powder separator (3) and the press collection crate (13); a press collection crate (13) that is located under the two or more conveyor belts (10, 11, 12); and a hydraulic press (14) beside the press collection crate ( 13 ).

Description

[0001] System for producing recycled polyurethane foam

[0002] The field of the invention

[0003] The object of the invention relates to a system for the production of recycled polyurethane foam containing polyurethane (PU) foam.

[0004] The state of the art

[0005] The scope of the present invention deals with a system for the production of recycled hard polyurethane foam.

[0006] Every year several millions of tonnes of polyurethane are produced, nearly a third of which is polyurethane hard foam. The latter is mainly used by the construction industry, but, in addition to this, significant users of polyurethane foam include the branch of industry dealing with the manufacture of refrigerators and the auto industry. The issue of handling these foams as waste arises, with which we have dealt in detail in our priority patent applications with numbers HU2400334 and PCT / HU2024 / 050085 .

[0007] There is a great demand for the recycling of PU foams, as every year a significant amount of PU foam waste is created. This amount is expected to increase exponentially in the following decades, as much hard PU-based insulation material produced in the past will reach the end of its lifecycle [Shangwen Zhu et al, 2023, J. Phys. : Conf. Ser. 2553 012001 and Gama, N.V.; Ferreira, A.; Barros-15 Timmons, A.; Polyurethane Foams: Past, Present, and Future; Materials, 2018, 11, 1841] . At present two main solutions are known of for the recycling of PU waste: chemical recycling and mechanical recycling. According to the state of the art several solutions dealing with the recycling of PU foams and production lines derived from these are known of .

[0008] The invention according to patent number EP2052827B1 discloses a method for the production of a plastic granulate , where the initial material is high-load capacity sound insulating film . In the first step of the method the film is chopped in the prechopper, then it is trans ferred to the post-chopper, where a granulate with a maximum diameter of 10 mm is created . Due to the composition of the film the composition of the granulate is heterogenous , therefore it is separated in an air-operated grader according to density . In other words , the light fraction is separated from the granulate , then the other undesirable substances , such as metal and the powder fraction are removed from the granulate via a filter system . At the end of the method, the remaining granulate is shaped using heat .

[0009] The method according to patent number EP0397971B1 relates to the environmentally friendly recycling of refrigeration apparatuses containing fluorinated hydrocarbons , particularly polyurethane foam components . First of all , the oil and the fluorinated hydrocarbon are drained from the motor of the refrigeration apparatus , following this the refrigeration apparatus is transported to the disassembly station, where the various components of the refrigeration apparatus , e . g . motor, refrigeration unit , mercury switch, nonferrous metals , heavy metals and aluminium, are removed . From here the refrigeration apparatus is transported on a conveyor belt to a closed processing chamber, where a first coarse chopping device is used to chop up the apparatus into fi st-si zed pieces . The coarsely chopped pieces are chopped further into smaller pieces in a subsequent fine chopping apparatus , after this , the magnetic metal components are separated in a first separator . After this the fluorinated hydrocarbons are removed from the pores of the remaining foam components in a so-called draining station by compressing the foam . Following this , the components , including the foam components , are subj ected to additional treatment , for example they are shaped into briquettes .

[0010] In the course of the method according to patent application number W02004022237A1 , first the materials containing PU are chopped into smaller pieces , creating so-called polyurethane flakes . The si ze of the flakes is reduced even more during a process including at least two steps . According to one of the embodiments , hydrosilicate is used as an additive . The PU powder obtained in this way may be reused in various industrial applications , such as in the production of new polyurethane products or it may be used as a filler material .

[0011] Patent number EP0433638B1 also deals with the disposal of old refrigerators and the utilisation of the materials that may be extracted from them . Part of the method is the chopping of the apparatuses , the separation of the PU in them, the grinding of this into a powder and it is this that facilitates the release of the residual CFG . The released gas mixture is collected, filtered and liqui fied .

[0012] Patent application number CN116653170A relates to the recycling of polyurethane foam, within this to the optimisation of the chopping process , where the obj ective is the breakdown of the foam and the separation of its components . By adj usting the position and angle of the cutting blades on the basis of realtime feedback from the processed material , the system ensures that the foam waste is broken down more thoroughly and more ef ficiently . A part of the system is a main unit , into which the foam is fed via a feed opening, inside it there is a sliding chamber with a crushing roller that chops up the foam, additionally that system also includes a separator .

[0013] In patent application number CN102516593A the PU foam waste is first chopped up into pieces 1- 10 mm in si ze . The undesired materials are removed from it , and so pure polyurethane foam particles remain . After this , a chemical reaction performed with special chemicals is carried out in a heated vessel , as a result of which polyol is obtained .

[0014] Patent application number JP2001349664A relates to vacuum insulation material that is made from waste hard polyurethane foam, and is mainly used for refrigerators , freezers and other low-temperature systems . During production the waste hard PU foam is chopped, then using air- flow grinding it is trans formed into a powder . The powder obtained in this way has an open-cell structure ( as opposed to the original closed cell foam) . The powder is mixed with a binder material , the mixture is pressed while hot , and so the core material of the insulation material is made .

[0015] In patent application number JP2001349492A foamed polyurethane powder obtained through the pulverisation of recycled rigid polyurethane foam is bound to a sheet-like foam using a binder, and a carrier chosen from plastic, rubber, metal or wood is laminated to at least one of the surfaces of the sheet-like foam . In this way, for example , a pulverising / mixing apparatus and also a unit is used for the casting step are applied in the method . Patent number CN106269803B discloses an apparatus for the safe disassembly of household refrigerators and the method relating to this . The main parts of the apparatus are the following : disassembly unit for the removal of the external elements ; cooling medium reclaiming unit ; chopper, which is for chopping the body of the refrigerator into larger pieces ; a secondary chopping machine is used for fine chopping; magnetic separator for selecting the magnetisable metals ; eddy current separator, which is used for separating the other metals ; airflow-based separation unit , with which the materials to be separated according to density may be separated; conveyor belts ; a unit for extracting the powder and its collection unit ; sensors for detecting temperature and other parameters ; a control unit for controlling the method .

[0016] Patent application number IN202311074886A discloses an automated device that is used for the recycling of waste polyurethane foam . After being chopped the polyurethane foam is trans formed into polyol with heat treatment , then isocyanate is added to it and in this way new polyurethane foam is created, which is then pressed .

[0017] Patent number EP0624444B1 deals with the reprocessing of polyurethane foam waste with a particle si ze of a maximum of 10 mm . During production the foam particles soaked in glue are forced from a closed space through shaped openings , in this way uni form, compact new foam products are obtained .

[0018] In patent application number EP0586644B1 the used polyurethane foam is recycled using inj ection moulding, the essence of which method is to achieve the product with as few method steps as possible . Patent application number W02023078802A1 discloses a method for the breaking down of polyurethane materials , particularly polyurethane foam, in other words this case deals with chemical recycling .

[0019] Patent application number US5534077A describes an apparatus that is for the extraction of polyurethane foam materials from refrigeration apparatuses containing polyurethane foam, which is performed without the chopping up of the apparatus .

[0020] In general , the systems related to solutions dealing with the recycling of PU foam according to the state of the art contain a unit suitable for thermoforming, which is used, for example , for extrusion, inj ection moulding , inj ection blow moulding or rotation moulding, furthermore during processing separate emphasis is placed on the processing of PU foam chopped to a particle si ze of under 10 mm, frequently more than one chopping unit is used in the interest of achieving this .

[0021] The obj ective of the present invention is to provide a system that is suitable for the production of recycled polyurethane foam from waste polyurethane foam, and which does not contain a unit suitable for thermoforming nor a secondary chopping unit either, and furthermore that is free of the disadvantages of the solutions according to the state of the art .

[0022] It was recognised that i f the known systems suitable for recycling PU are trans formed so that they do not contain more than one chopping unit and, also , do not contain a unit suitable for thermoforming, then with this system high-porosity, recycled polyurethane foam blocks with a high PU content and lower binder content and with an open-cell structure may be produced in an energy-ef ficient and cost-ef fective way that have good insulation properties , mechanical strength, elevated fire resistance and that are structurally stable .

[0023] A brief presentation of the figures

[0024] Figure 1 shows an axonometric view of the structure of the system according to the invention for the production of recycled polyurethane foam .

[0025] Figure 2 shows a side view of the rotating drum powder separator of the system according to the invention .

[0026] Figure 3 shows a front view of the rotating drum powder separator of the system according to the invention .

[0027] Figure 4 shows the automatic feeder according to an embodiment of the system according to the invention .

[0028] Figure 5 shows the rotating disc mixing spray head depicted above a conveyor belt according to an embodiment of the system according to the invention .

[0029] Figure 6 shows the water atomising unit according to an embodiment of the system according to the invention .

[0030] Figure 7 shows the crate moving unit according to an embodiment of the system according to the invention .

[0031] A brief description of the invention On the basis of the above recognitions the set obj ective was solved as planned with the design of the components of the system, primarily implemented for use for the production of recycled polyurethane foam containing hard or soft polyurethane foam .

[0032] The obj ect of the present invention relates to a system for the production of recycled polyurethane foam, which contains the following :

[0033] - a miller, which has an input and an output and in the space of the miller there are one or more elements arranged adapted for chopping, the latter i s particularly understood to mean tempered rotating blades located on a rotor and fixed counter-blades ;

[0034] - a rotating drum powder separator is positioned compared to the outlet of the miller in such a way that its inlet hopper is positioned so that the PU foam chips are fed into the rotating drum powder separator by gravity;

[0035] - two or more conveyor belts that link the rotating drum powder separator wit

[0036] - h the press collection crate ;

[0037] - one or more magnets that are positioned after the first conveyor belt between the rotating drum powder separator and the press collection crate ;

[0038] - a press collection crate that is located under the two or more conveyor belts ;

[0039] - and a hydraulic press beside the press collection crate .

[0040] According to a preferable embodiment the system for producing recycled polyurethane foam contains , apart from the above , an automatic feeder that is located between the first conveyor belt and the second conveyor belt and which contains a buf fer hopper, a belt , a driven roller by the second conveyor belt that guides the belt back towards the hopper, an electrical control cabinet , an adj ustable guide shutter .

[0041] According to another preferable embodiment , the system for producing recycled polyurethane foam contains a rotating disc mixing spray head that is located above the third conveyor belt , and which contains a vertical-shaft electric motor, a drilled disc with an external shell that sits on the shaft of the electric motor, at least two liquid tanks are connected to the drilled disc via at least two pipeline pairs , at least two pneumatic membrane pumps that are located outside the liquid tanks , at least two pneumatic feed heads , these are located at the end of the pipelines and at least two flow meter instruments are connected to these , and a frequency converter that is connected to the electric motor .

[0042] According to a further preferable embodiment , the system for producing recycled polyurethane foam contains a water atomising unit that is located under the second conveyor belt and which contains a spray head, a pneumatic pressure-resistant valve , a manometer, a water amount adj ustment valve , a support bracket and a manual switch valve .

[0043] According to yet another preferable embodiment the system for producing recycled polyurethane foam contains a crate-moving unit that is positioned in the same plane and axial direction according to the press collection crate . According to a further embodiment of the system for producing recycled polyurethane foam, the rotating drum powder separator contains an inlet hopper, an outlet hopper, a perforated rotating drum with a bore diameter of a maximum of 10 mm, a motor, a frequency converter, a li ft device , an extraction funnel , a drum cleaning brush and an electrical cabinet .

[0044] According to a further embodiment of the system for producing recycled polyurethane foam, the external diameter of the drilled disc of the rotating disc mixing spray head is between 80 and 150 mm, the height of the shell o f the drilled disc is between 10 and 40 mm, the distance between the drilled disc and the second conveyor belt is between 200 and 500 mm .

[0045] According to a more preferable embodiment of the system for producing recycled polyurethane foam, the drilled disc of the rotating disc mixing spray head contains evenly arranged 6 to 12 mm diameter bores in the lower 5 to 20% of the height of the disc, where the height of the shell of the disc is 100% .

[0046] According to another more preferable embodiment of the system for producing recycled polyurethane foam, the material of the drilled disc is stainless steel or aluminium .

[0047] A detailed description of the invention

[0048] In figure 1 an axonometric view of the system for the production of recycled polyurethane foam 100 may be seen, which serves for the recycling of hard or soft polyurethane foams . The said system for the production of recycled polyurethane foam 100 contains the following components :

[0049] - The miller 1 , which accordingly has an input 2a and an output 2b, and in the internal space of the miller 1 there are one or more elements arranged adapted for chopping, the latter is particularly understood to mean tempered rotating blades located on a rotor and fixed counter-blades . Using the miller 1 , the milling takes place mechanically, based on the shear principle , however, impact systems performing a similar purpose also exist . The obj ective with miller 1 is the milling ( chopping) of the PU hard or soft foam raw material , to a particle si ze of up to 30 mm .

[0050] - The rotating drum powder separator 3 is positioned compared to the output 2b of the miller 1 ( see figures 2 and 3 ) so that its inlet hopper 4a is positioned in the way easily visible in figure 1 so that the PU foam chips are fed into the rotating drum powder separator 3 by gravity . The rotating drum powder separator 3 contains a cylindrical external 5 and a stainless steel perforated internal rotating drum, the centri fugal force is exploited in the separation of the PU foam chips according to si ze , the separated (not used) powder fractions are collected in the central collector with the help of the separate extraction unit ( the latter is not a part o f the system marked with reference sign 100 ) . The rotation of the drum is driven by the motor 6 regulated by a frequency converter, the angle of inclination of the drums may be mechanically adj usted between 5 and 20 ° as a consequence of the li ft device 7 , in this way the speed of progress of the material and the ef ficiency of separation may be harmonised . The fine PU powder ( PU foam particles under 10 mm) passes to a separate extraction unit via the extraction funnel 8 , which extraction unit , as mentioned above , is not a part of the system for the production of recycled polyurethane foam 100 , while the useful PU fraction of 10 mm in si ze or greater passes further along in the system marked with reference sign 100 . The rotating drum powder separator 3 is fitted with an electrical control cabinet 9 , a safety housing and indicator signals , therefore it may be used as an independent and automated unit in the system for the production of recycled PU foam 100 . The proportion of the fine PU powder separated by the rotating drum powder separator 3 is 5 to 25 mass% , depending on the quality of the incoming PU foam .

[0051] - The rotating drum powder separator 3 is linked to the press collection crate 13 by two or more conveyor belts ( 10 , 11 , 12 ) .

[0052] - Part of the system for the production of recycled PU foam 100 includes one or more magnets , which may be electromagnets or ferromagnets as well , which are located after the first conveyor belt between the rotating drum powder separator 3 and the press collection crate ( the magnets is not separately indicated in figure 1 ) . In the solutions according to the state of the art conveyor belts are usually made from PVC or PU, and the guiding of the materials transported by them is not solved . A speci ficity of the collected PU foam is that metal swarf gets into the foam waste during cutting and chopping . Therefore , the insertion of magnets for selecting metals at one or more points in the production line becomes necessary, with which the undesirable magnetisable metal elements may be selected out .

[0053] - A part of the system also includes the press collection crate 13 , which is positioned under the two or more conveyor belts 10- 12 .

[0054] - A hydraulic press 14 is also located beside the press collection crate 13 . I f the press collection crate 13 becomes full , it is pushed over to under the hydraulic press 14 , in other words the press collection crate 13 does not only serve for collecting the PU foam chips , but also for resting the PU foam in the press collection crate 13 closed with pressing force , during which time the foam block is formed . The amount of pressing force used is between 1 and 15 MPa .

[0055] In addition to the above , the system for the production of recycled polyurethane foam 100 may also contain an automatic feeder 15 ( see figure 4 ) , which is located between the first conveyor belt 10 and the second conveyor belt 11 . The automatic feeder 15 contains a buf fer hopper 16 , belt 17 , a driven roller by the second conveyor belt 11 that guides the belt 17 back towards the buf fer hopper 16 ( in other words the belt is a closed loop ) , the electric control cabinet 19 and adj ustable guide shutter 20 , which may be positioned with securing bolts . The frame structure of the automatic feeder 15 is a welded steel frame , with a painted surface , and it is necessary to adapt the dimensions of the structure to the production line . The function of the automatic feeder 15 is the temporary storage of the polyurethane foam with a particle si ze of between 10 and 30 mm that has had the powder separated from it in the buf fer hopper 16 , then its even, regulated feeding onto the second conveyor belt 11 . The precise feeding ensures that miller PU foam raw material of the same si ze is avai lable in every cycle for the later binder spraying, and this contributes to the homogeneity of the recycled PU foam blocks . It should be noted that within the scope of the present speci fication i f we define a range between 10 and 30 mm, then the concrete numerical values indicated as the limit values of the range are also viewed as being a part of the range ( in other words the range also includes the si zes of 10 mm and 30 mm) .

[0056] The speed of rotation of the driven roller 18 may be adj usted to between 50 and 200 rpm using the frequency converter, furthermore its height may be adj usted in the range of 0- 140 mm compared to the belt height using a manual wheel and Vernier scale , and in this way the fed material flow rate (up to 5 . 0 kg / minute ) may be easily controlled . The adj ustment of the appropriate height of the driven roller 18 is important in order to avoid faulty behaviour, such as feed blockages or belt mistracking, additionally the ability to adj ust both the speed of revolution and the roller height makes it possible to quickly change the recipe , all without any greater modi fication the production line . Using the 0- 10 scale potentiometer located on the electrical control cabinet 19 the operator adj usts the roller speed, additionally the driven roller 18 may also be adj usted to go forwards or backwards , and i f necessary there is also an emergency stop button available that completely cuts of f the power to the automatic feeder 15 . It is necessary to clean the automatic feeder 15 every day with the power switched of f , which is performed with a cleaning agent and compressed air . During operation it is forbidden to approach the zone above the buf fer hopper 16 and the belt 17 .

[0057] The system for the production of recycled polyurethane foam 100 may also contain a rotating disc mixing spray head 21 ( see figure 5 ) , which is located above the third conveyor belt 12 , and to which a vertical-shaft electric motor 22 is connected, a part of the rotating disc mixing spray head 21 is the drilled disc 23 with an external shell 24 , which sits on the shaft of the electric motor 22 . At least two liquid tanks ( their position is not visible in the figures ) are connected to the drilled disc 23 via at least two pipeline pairs 25a and 25b, which are positioned as required next to the system for the production of recycled polyurethane foam 100 . A pneumatic membrane pump is located outside of each of the two liquid tanks , as a result of which the maximum achievable liquid transportation rate is 2000 g / minute . The pneumatic feed heads 26a and 26b are located at the ends of the pipelines 25a and 25b, a flow meter is connected to each of these . The electric motor is regulated by a frequency converter . The precise amount of the liquid to be fed may be controlled with the pneumatic feed heads 26a and 26b . The rotating disc mixing spray head 21 simultaneously ensures the radial , turbulent mixing together of the two liquids ( diphenylmethane diisocyanate prepolymer or abbreviated as MDI- prepolymer and lignin solution) and their atomisation caused by the centri fugal force , and so the binder material is dispersed onto the PU foam chips passing on the third conveyor belt 12 in fine , homogenous droplets , thereby premixing in a separate liquid tank and the phase separation of the liquid components may be avoided as may the loss derived from the li fetime limitation of the mixture .

[0058] The external diameter of the drilled disc 23 of the rotating disc mixing spray head 21 is between 80 and 150 mm, the height of the external shell 24 of the drilled disc 23 is between 10 and 40 mm, the distance between the drilled disc 23 and the second conveyor belt 11 is between 200 and 500 mm . The external shell 24 prevents the fed-in liquid from flowing out in an uncontrolled way onto the third conveyor belt 12 moving under it , in other words the liquid must pass through the perforated bores .

[0059] The drilled disc 23 of the rotating disc mixing spray head 21 contains evenly distributed bores with a diameter of 6 to 12 mm in the lower 5 to 20% of the height of the disc, where the height of the shell of the disc is viewed as 100% , and it is through which bores the binder mixture covers the PU foam chips passing underneath it on the second conveyor belt 12 in fine droplets as a consequence of the centrifugal force , it is also a consequence of the even distribution of the bores that the distribution of the binder displays no banding . For a person skilled in the art it is obvious that with the same diameter of disc smaller diameter bores would result in a finer spray mist and a lower flow rate , a larger bore diameter would result in a coarser droplet si ze and a greater yield, in other words the bandwidth of the spray pattern varies in proportion with the diameter of the bores . It is also obvious for a person skilled in the art that by increasing the rate of rotation of the drilled disc 23 the tangential speed of the spray edge will increase proportionately, and so the average droplet si ze will decrease , the covered spatial width will increase , while the same about of fed liquid will be sprayed onto the PU foam chips in a thinner, more even film . To summarise , the spray pattern of the rotating disc mixing spray head 21 may be fine-tuned with the four independent parameters : disc diameter, bore diameter, rate of rotation, supply mass flow rates . A quick change of recipe may be implemented by merely replacing the drilled disc 23 , or by readj usting the frequency converter and the pneumatic feed heads .

[0060] The drilled disc 23 is preferably from stainless steel or aluminium, as these are resistant to weak acids and weak alkaline solutions . It is obvious for a person skilled in the art that the disc may be made from any material that is resistant to the mixture of the lignin solution and the MDI-prepolymer . Another advantage of the rotating disc mixing spray head 21 is that its cleaning may be performed in j ust a few minutes using steam, as there are no blind spots in the structure and the steam also prevents the blocking of the bores .

[0061] The system for the production of recycled polyurethane foam 100 preferably also contains a water atomising unit 27 operating on the pneumatic principle , which is located under the second conveyor belt but above the press collection crate 13 ( see figure 6 ) , accordingly its task is to moisten the PU foam chips coated with the MDI-prepolymer and the lignin solution with a water mist . The addition of water initiates the reaction for the binder to actually create the bonds . On the other hand, as a result of its evaporation, the water cools and so delays the exothermic reaction, and so the large-volume recycled PU foam block may be shaped for a suf ficient amount of time (by pressing in this case ) , which is also an energy-e f ficient solution . A reaction between the MDI-prepolymer and the PU foam chips lasting j ust moments is problematic because the lower part of the formed foam block quickly sets through, even before all of the mixture is placed into the press mould, which would result in an inhomogeneous structure . This process di f fers from the so-called heated processes known of from the literature in which the binder is heated . In those cases where heating is used instead of cooling the cycle duration is signi ficantly shorter, the scope of products is limited, and are mainly suitable for the production of panels . However, the water mist sprayed by the water atomising unit 27 results in a delayed chemical reaction, and an extended cycle duration, which make a broader range of products possible , and all this in a cost-ef fective way ( there is no need for external cooling or heating either ) . The PU foam chips coated with the mixture of MDI-prepolymer and lignin solution passes using gravity through a water mist zone in which the si ze of the water droplets may be adj usted . The water mist thoroughly moistens then entire particle surface , while due to the evaporation of the water, it cools the material down by 3-5 ° C before being pressed . Due to this the reaction only starts after the material has reached the press collection crate 13 , i . e . it starts during pressing, which makes the formation of homogenous , large recycled PU blocks possible .

[0062] The water atomising unit 27 contains a 3D-adj ustable spray head ( for example , the angle of inclination may be adj usted by ± 30 ° ) , which by mixing the water and air flows creates a fine water mist ; a pneumatic pressure-resistant valve , which controls the air pressure required for the atomisation in the range of 1 . 5 to 6 bar ; a manometer, which is fitted to the pneumatic pressure- resistant valve , this displays the set pressure value ( scale of 0 to 6 bar ) ; a water amount adj ustment valve , which restricts or increases the water flow in the range of 0 - « 450 ml (minutebased) , the value of this may be read from the flow meter ; a support bracket 29 with adj ustable height and which may be rotated, the spray head 28 and the manual switch valve are secured to this . As it may be easily seen from the above , in the case of the water atomising unit 27 , all the structural elements are exclusively pneumatic or mechanical , they do not contain electrical components , which is s igni ficant because it is not recommended to use a source of ignition in an isocyanate vapour environment . Depending on the composition of the PU foam chips and the desired cycle duration the operator performs the adj ustment of the pressure and water flow rate , the recommended initial values are air pressure o f 3 bar and a water flow rate of 250 ml / minute . Before maintenance the pneumatic pressure resistant valve must be closed, then the residual pressure in the water atomising unit 27 must be released . The spray head 28 must be cleaned every day, and during operation, i f the spray pattern becomes distorted then it must be cleaned externally with water, i f necessary an ultrasound cleaner must be used . As a result of the structure of the water atomising unit 27 it is also suitable for implementing a quick switch over in product , as the pressure and water amount may be modi fied almost immediately, in addition the angle of inclination of the spray head 28 may be adj usted in j ust a few minutes . In general , high- pressure mixing heads are used in the PU industry, however these do not have the advantages explained in detail above .

[0063] The system for the production of recycled polyurethane foam 100 preferably contains a crate moving unit 30 ( see figure 7 for a close-up view) , which is in the same plane and axial direction as the press collection crate 13 , thereby minimising mechanical stress resulting from centre of mas s shi fts . The press collection crate 13 may be connected to the crate moving unit 30 in one motion via a mechanical rapid coupl ing towing eye , thereby simple connection and stable power trans fer may be ensured . The cyclic, hori zontal motion ( crate swinging) performed during press collection crate 13 layering results in a homogenous recycled PU foam block . In the case of the solutions according to the state of the art , the crates are usually in a fixed position, and homogeneity is attempted to be achieved rather by mixing (using a drum or blade mixer ) . The crate moving unit 30 of fers a solution to the problems of particle accumulation and density gradient caused by gravitational feeding, thereby supplementing the ef ficiency of the powder separation technology . The dynamic movement of the crate moving unit 30 prevents local accumulation of the foam chips , in this way sorting according to particle si ze and feed concentration may be avoided .

[0064] The PU foam chips coated in binder passes into the press collection crate 13 by gravity, typically after freefall of 1 . 5 to 2 metres . While falling the particles frequently accumulate in an irregular way, which signi ficantly damages the homogeneity of the PU foam block being created . In order to prevent particle accumulation, the crate moving unit 30 moves the press collection crate 13 during the feeding cyclically, to and fro along an axis using a linear drive system operating with a chain drive , thereby ensuring the even distribution of the PU foam chips layer by layer . The frequency and speed of the movement may be continuously regulated from the operation interface . The control of the crate moving unit 30 takes place through a control unit integrated in the control panel , it is here that the speed and cyclicity ( the duration of the to and fro movement ) may be set . The local operation controls located in the crate moving unit 30 enable the manual control of the moving unit for the purpose of maintenance or troubleshooting, in addition it has a signalling column ( light signal ) which provides visual indication of the operation state . Emergency stop buttons have also been built into the control panel and also into the machine unit , at the terminal positions there are safety terminal position switches to facilitate the electronic monitoring of the limits of position . In summary, the crate moving unit 30 overcomes the disadvantages occurring during mechanical or pneumatic mixing (breakage , powder separation, drying out ) , and so is a signi ficant step to more even, structured recycling of recycled PU foam blocks .

[0065] The system for the production of recycled polyurethane foam 100 may optionally contain a cutting and / or coating unit immediately beside the press collection crate 13 , with which the finished PU foam block may be cut to shape , the cut-to-shape foam blocks may be optionally laminated, or provided with a coating corresponding to the purpose .

[0066] The rotating drum powder separator 3 already mentioned above contains the following : an external drum 5 placed on the li ft device 7 ; an inlet hopper 4a and an outlet hopper 4b are positioned at the ends of the external drum 5 , on opposite sides ; a perforated internal rotating drum with bores of a diameter of up to 10 mm is contained in the inside of the external drum, a drum cleaning brush may be found between the two ; the motor 6 and the frequency converter may be found at the end of the external drum 5 towards the outlet hopper 4b ; the extraction funnel 8 is located on the base of the external drum 5 ; apart from the above the rotating drum powder separator 3 also contains an electrical cabinet 9 .

[0067] The reason it is important to separate the particles smaller than 10 mm from the milled PU foam is that these drastically increase the method' s demand for binder (MDI-prepolymer ) , what is more , the hard PU powder damages the integrity of the panels as a rigid inclusion . The rotating drum powder separator 3 separates the undesirable PU fractions using centri fugal force . The PU foam chips between 10 and 30 mm may be bounding a homogenous way, due to the preferable selection of si ze range binder material use is reduced by as much as 15 to 30% compared to the case when the initial material also contains particles under 10 mm in si ze . The rotating drum powder separator 3 functions with all PU foams with a density of 5 to 200 kg / m3, its capacity per hour is between 0 and 120 kg (using standard 40 kg / m3density foam as a basis ) , depending on the foam density and the settings , the mass flow rate is 200-400 kg / h, or an average of 300 kg / h in continuous operation .

[0068] Soft PU foams (with a density of 15- 60 kg / m3) are mainly furniture and mattress foams . As a result of their flexibility, the particles under 10 mm leave the perforated internal rotating drum of the rotating drum powder separator 3 easily .

[0069] More fine fractions are created from hard PU foams (with a density of 30-200 kg / m3) during milling due to their high speci fic mass that are unable to leave immediately through the perforations , and for this it is necessary to adj ust the angle of inclination and speed of rotation of the rotating drum powder separator 3 , which may be performed using the li ft device 7 , an embodiment of which is a powder-coated steel structure , so it may be used both in a covered production hall and in a semiexterior environment .

[0070] Within the scope of the present invention fine powder is defined as the PU granulate with a particle si ze of under 1 mm . Within the scope of the present invention small particles are understood to mean chips of a si ze of between 1 and 10 mm (not including the chips of precisely 10 mm, see the text above in connection with the range 10 to 30 mm) , which as a consequence of its si ze leaves the perforated internal drum with the airflow, this fraction can optionally be recycled or pressed as a filler material .

[0071] The useful fraction is the powder- free foam chips with a si ze of between 10 and 30 mm, it is this fraction that is processed in the system . It is obvious for a person skilled in the art that the stainless steel performed internal rotating drum may even be replaced, as so the si ze of the perforations may be selected according to the qual ity of the material to be processed, i . e . the perforations may be selected for the desired cutting limit . Furthermore , the internal cleaning of the perforated internal drum is facilitated by an adj ustable brush . The daily cleaning of the rotating drum powder separator 3 is performed at the end of the shi ft after it has been disconnected from the power supply, the internal surface of the drum maybe blown clean with compressed air .

[0072] The drive chain of the rotating drum powder separator 3 may be , for example , a 0 . 55 kW lEC-motor ( 6 ) with a W 63 worm gearbox, rpm regulation may be ensured by a Siemens V20 frequency converter, but it is obvious for a person s killed in the art that these functions may also be performed by other suitable devices . The extraction funnel 8 is located on the side of the external drum 5 and ensures the immediate extraction of the fine powder fraction with the help of an extraction system . The electrical cabinet 9 contains the main switch, reset button, start / stop button, potentiometer rotational speed regulator with scale of 0-10 , emergency stop switch easily accessible from any direction . Furthermore , the rotating drum powder separator 3 has a safety housing, a grid preventing operators from reaching inside the inlet 4a and outlet 4b hoppers , a closed frame under the external drum 5 .

[0073] The rotating drum powder separator 3 , which is an apparatus with adj ustable angle of inclination and regulated speed of rotation, and which enables the implementation of a compact separation method step, combines three di f ferent physical ef fects ( centri fugal force , gravitational fall time , airflow extraction) in a single step, with its exchangeable perforated internal rotating drum it may be adapted for the milling fineness of any PU foam, it is integrated with an independent extraction system, therefore it does not require central extraction dependent on the air-status of the miller machine , and because of the ability to tune the parameters it is suitable for the separation of flexible and rigid foam fractions with a density of 5-200 kg / m3. In addition to this , the advantage of the rotating drum powder separator 3 is that it signi ficantly reduces the amount of binder material used, and, thereby, the costs spent on this , furthermore it also improves the homogeneity of the recycled PU foam .

[0074] The operation of the system 100 for the production of recycled polyurethane foam is presented via an example .

[0075] Example : starting with PU foam with a density of 40 kg / m3

[0076] - The collected PU foam ( 60 mass% ) is milled using the miller 1 to a maximum si ze of 30 mm . The milled PU foam falls by gravity through the output 2b of the miller 1 into the inlet hopper 4a of the rotating drum powder separator 3 .

[0077] - The rotating drum powder separator 3 is started using the start / stop button after switching on the main switch . The PU foam chips pass out of the inlet hopper 4a and into the perforated internal rotating drum . The speed of rotation is set using the potentiometer to 50 min- 1, the angle of inclination of the rotating drum powder separator 3 is set to 10 degrees using the manual lever, which is related to the so-called fall time . Due to the ef fect of centri fugal force the larger si zed foam pieces are swept to the shell while the fine PU powder (under 1 mm) and the PU foam chips of between 1 and 10 mm (not including the precisely 10 mm pieces) exit through the bores out into the external drum. From here the fine PU powder and the PU foam chips between 1 and 10 mm is sucked out by the separate extraction unit, all this is collected in a collection vessel, which in the present case is a 0.5 m3plastic sack.

[0078] The bore diameter of the bores in the perforated internal rotating drum of the rotating drum powder separator 3 is: 9.9 mm.

[0079] The separation rate of the fine PU powder is: 90-95%.

[0080] The removal rate of the PU foam chips between 1 and 10mm is: over 80%.

[0081] The mass flow rate of the rotating drum powder separator 3 is an average of 300 kg / h in continuous operation.

[0082] The drive chain of the rotating drum powder separator 3 is a 0.55 kW TEC-motor with a W 63 worm gearbox, the rpm regulation is ensured by a Siemens V20 frequency converter (operating at 230V AC, max. 750VA load) . The PU foam chips of a size between 10 and 30 mm, i.e. the preferable PU fraction, leaves the rotating drum powder separator 3 through the outlet hopper 4b directly onto the first conveyor belt 10, from here it progresses in the direction of the automatic feeder 15.

[0083] - The magnetisable metal swarf to be found in the preferable PU fraction is selected out by the ferromagnet located after the first conveyor belt 10.

[0084] - The PU foam chips now free of magnetisable metals is taken evenly by the automatic feeder 15 from the first conveyor belt 10 onto the second conveyor belt 11.

[0085] The speed of rotation of the driven roller 18 is: 50 rpm, its height is 40 mm, the material flow rate of the automatic feeder 15 was 1.5 kg / minute. - The PU foam chips pass from the second conveyor belt 11 to the third conveyor belt 12. Above the latter, the rotating disc mixing spray head 21 mixes and atomises the MDI- prepolymer (25 mass!) and the lignin solution (8 mass%) , in this way the binder material is dispensed onto the PU foam chips travelling on the third conveyor belt 12 in fine, homogenous droplets.

[0086] The diameter of the drilled disc 23: 100 mm.

[0087] The height of the shell 24 of the drilled disc 23: 40 mm.

[0088] The distance between the drilled disc 23 and the third conveyor belt 12 is 350 mm.

[0089] Bore diameter (in the case of evenly distributed bores) : 3.5 mm.

[0090] The material of the drilled disc 23: stainless steel.

[0091] The dispensing rate of the binder material: 200 - 1400 g / minute .

[0092] - The PU foam chips coated in MDI-prepolymer and lignin solution (together: binder material) is moistened by the water mist (7 mass!) created by the water atomising unit 27 located in the space under the second conveyor belt. The PU foam chips pass through the water mist zone by gravity.

[0093] The pressure of the air required for atomising the water: 3 bar .

[0094] The pressure value set in the water atomising unit 27: 1.5 - 6 bar.

[0095] The water amount adjustment valve, kept in the 250 ml (minute-based) range.

[0096] - Following this the PU foam chips coated with binder material and moistened passes by gravity into the press collection crate 13, where the cyclical, horizontal motion (crate swinging) of the crate moving unit 30 during layering prevents particle accumulation. - The press collection crate 13 is moved to under the hydraulic press 14, where the delayed chemical reaction takes place, and the recycled PU foam block is formed. The recycled PU foam block remained in the press crate for 12 hours .

[0097] Compressive force applied: 150 bar.

[0098] - The finished recycled PU foam block is cut to shape with a cutting and coating unit, the foam blocks cut to shape are laminated, provided with a coating.

[0099] The adhesive testing of the powder-free PU fraction showed 18% less binder material use and a more even insulating strength. Taking 40 kg / m3incoming material density value into consideration, the characteristics of the resultant product are: Material density: 90 kg / m3;

[0100] Compressive strength in the case of 10% deformation (kPa) : 150 ( kPa) ;

[0101] Flexural modulus (E) : 2000 (kPa) .

[0102] Energy used during production: 4 KWh / block. Energy saved due to leaving out the steaming process: 7 KWh / block.

[0103] The exothermal reaction of the MDI-prepolymer and the lignin raises the temperature of the foam block to about 70 °C, therefore it was not necessary to use external steam for the crosslinking .

[0104] The about 10 kg of 120 °C saturated steam that was not used would have required 22 MJ condensation heat, and an additional ~ 4 MJ of heat for heating the water from 20 °C to 120 °C, which is a saving of a total of ~ 26 MJ, i.e. ~ 7.3 kWh. This profit corresponds to an energy-equivalent of about 0.8 m3of natural gas or 0.6 litres of heating oil in every production cycle. 1

[0105] Finally, the invention is not limited to the embodiment of the system for the production of recycled polyurethane foam 100 disclosed above , instead it may be implemented in multiple ways within the scope of protection defined by the claims .

[0106] Reference signs :

[0107] 100 - system for the production of recycled polyurethane foam

[0108] I - miller

[0109] 2a - miller input

[0110] 2b - miller output

[0111] 3 - rotating drum powder separator

[0112] 4a - rotating drum powder separator inlet hopper

[0113] 4b - rotating drum powder separator outlet hopper

[0114] 5 - rotating drum powder separator external drum

[0115] 6 - rotating drum powder separator motor

[0116] 7 - rotating drum powder separator li ft device

[0117] 8 - rotating drum powder separator extraction funnel

[0118] 9 - rotating drum powder separator electrical control cabinet

[0119] 10 - first conveyor belt

[0120] I I - second conveyor belt

[0121] 12 - third conveyor belt

[0122] 13 - press collection create

[0123] 14 - hydraulic press

[0124] 15 - automatic feeder

[0125] 16 - automatic feeder buf fer hopper

[0126] 17 - automatic feeder belt

[0127] 18 - automatic feeder driven roller

[0128] 19 - automatic feeder electrical control cabinet

[0129] 20 - automatic feeder guide shutter

[0130] 21 - rotating disc mixing spray head

[0131] 22 - rotating disc mixing spray head electric motor

[0132] 23 - rotating disc mixing spray head drilled disc

[0133] 24 - drilled disc external shell

[0134] 25a - liquid tank pipeline

[0135] 25b - liquid tank pipeline

[0136] 26a - first pneumatic feed head 26b - second pneumatic feed head

[0137] 27 - water atomising unit

[0138] 28 - water atomising unit spray head

[0139] 29 - water atomising unit support bracket 30 - crate moving unit

Claims

Claims1. System for the production of recycled polyurethane foam (100) , which contains:- a miller (1) , which has an input (2a) and an output (2b) and in the space of the miller there are one or more elements arranged for chopping, which are tempered rotating blades located on a rotor and fixed counter-blades;- two or more conveyor belts (10, 11, 12) that link said rotating drum powder separator (3) with a press collection crate ( 13 ) ;- one or more magnets that are positioned after the first conveyor belt (10) between the rotating drum powder separator (3) and the press collection crate (13) ;- a press collection crate (13) that is located under the two or more conveyor belts (10, 11, 12) ; and a hydraulic press (14) beside the press collection crate (13) , characterised by that the system for producing recycled polyurethane foam contains (100) , apart from the above- a rotating drum powder separator (3) located in such a way compared to the miller output (2b) that an inlet hopper (4a) of which is positioned so that the PU foam chips pass by gravity from the miller (1) into the rotating drum powder separator (3) .

2. The system for the production of recycled polyurethane foam(100) according to claim 1, characterised by that it contains an automatic feeder (15) that is located between the first conveyor belt (10) and the second conveyor belt (11) and which contains a buffer hopper (16) , a belt (17) ,a driven roller (18) by the second conveyor belt (11) that guides the belt (17) back towards the buffer hopper (16) , an electrical control cabinet (19) , an adjustable guide shutter (20) .

3. The system for the production of recycled polyurethane foam (100) according to any of claims 1 to 2, characterised by that it contains: a rotating disc mixing spray head (21) that is located above the third conveyor belt (12) ; a vertical-shaft electric motor (22) , a drilled disc (23) with an external shell (24) that sits on the shaft of the electric motor (22) ; at least two liquid tanks are connected to the drilled disc (23) via at least two pipeline pairs (25a, 25b) ; at least two pneumatic membrane pumps that are located outside the liquid tanks; at least two pneumatic feed heads (26a, 26b) that are located at the end of the pipelines (25a, 25b) ; at least two flow meter instruments are connected to the said at least two pneumatic feed heads (26a, 26b) , and a frequency converter that is connected to the electric motor (22) .

4. The system for the production of recycled polyurethane foam (100) according to any of claims 1 to 3, characterised by that it contains a water atomising unit (27) that is located under the second conveyor belt (11) and which contains a spray head (28) , a pneumatic pressure-resistant valve, a manometer, a water amount adjustment valve, a support bracket (29) and a manual switch valve.

5. The system for the production of recycled polyurethane foam (100) according to any of claims 1 to 4, characterised bythat it contains a crate-moving unit (30) that is positioned in the same plane and axial direction as the press collection crate (13) .

6. The system for the production of recycled polyurethane foam (100) according to any of claims 1 to 5, characterised by that the said rotating drum powder separator (3) contains an inlet hopper (4a) , an outlet hopper (4b) , a perforated rotating drum with a bore diameter of a maximum of 10 mm, a motor (6) , a frequency converter, a lift device (7) , an extraction funnel (8) , a drum cleaning brush and an electrical cabinet (9) .

7. The system for the production of recycled polyurethane foam (100) according to any of claims 3 to 6, characterised by that the external diameter of the drilled disc (23) of the rotating disc mixing spray head (21) is between 80 and 150 mm, the height of the shell (24) of the drilled disc (23) is between 10 and 40 mm, the distance between the drilled disc (23) and the second conveyor belt (11) is between 200 and 500 mm.

8. The system for the production of recycled polyurethane foam (100) according to any of claims 3 to 7, characterised by that the drilled disc (23) of said rotating disc mixing spray head (21) contains evenly arranged 6 to 12 mm diameter bores in the lower 5 to 20% of the height of the drilled disc (23) , where the height of the shell (24) of the disc is 100%.

9. The system for the production of recycled polyurethane foam(100) according to any of claims 3 to 8, characterised bythat the material of the drilled disc (23) is stainless steel or aluminium.

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