Reaction of Polyurethane in a Reactant with a Tapered Shape

Abstract

The present invention relates to a continuous process for reacting a plastic material containing polyurethane, comprising the following steps, namely a reaction mixture comprising - a plastic material present as a solid and containing polyurethane, and further - an aqueous medium optionally containing reaction additives, providing a reaction mixture, in which the mass ratio of water of the aqueous medium to polyurethane in the reaction mixture is 0.6 to 1 or less; conveying the reaction mixture by means of a first screw conveyor arranged in a first line to a filling opening designed as a pressure lock of a reactor which tapers in the conveying direction at at least one end region; conveying the reaction mixture by means of a reactor screw conveyor arranged in the reaction vessel to the end region of the reactor at a temperature of 180 °C to 270 °C and a pressure of > 1 bar to 60 bar; transferring, in the end region of the reactor, the reaction mixture thus pressure- and heat-treated via a discharge opening designed as a pressure lock to a second line; conveying the pressure- and heat-treated reaction mixture by means of a second screw conveyor arranged in the second line; providing an evaporation zone in the second line at a temperature higher than the temperature in the reactor; removing gaseous components in the evaporation zone via at least one degassing point and obtaining, in the evaporation zone or downstream of the evaporation zone, a reaction mixture which has been pressure- and heat-treated and from which the gaseous components have been removed; a method comprising the above steps.

Description

Technical Field

[0001] The present invention relates to a method for reacting a plastic material containing polyurethane and a corresponding apparatus.

Background Art

[0002] Due to its many adjustable properties, polyurethane is widely used in industrial and household products. Examples of such products are foams, paints, adhesives, casting materials, hoses, seals, floor coverings, mattresses, automotive parts, parts of sports equipment, parts of shoes, etc.

[0003] Therefore, when the corresponding products are damaged or reach their service life, a large amount of polyurethane waste is generated.

[0004] Therefore, attempts have been made in the past to recycle polyurethane. For example, European Patent No. 01976719 describes a method of hydrolyzing a polyurethane resin by contacting it only with water at a high temperature.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem of the present invention is to provide an improved method.

Means for Solving the Problems

[0007] The present invention becomes apparent from the features of the independent claims. Advantageous developments and embodiments are the subject matter of the dependent claims.

[0008] Within the scope of the present invention, the plastic material is understood to be a material containing plastic, ranging from pure plastic to a mixture containing plastic. The term "plastic" is used in its general sense and refers to substances produced synthetically, for example, substances produced within the scope of organic synthesis, such as polymers produced by polymerization, polyaddition, and / or polycondensation from one or more different monomers. Plastics are generally classified into thermosetting resins, thermoplastic resins, elastomers, and thermoplastic elastomers. Well-known examples of plastics are polyethylene, polycarbonate, polyacrylic, polymethacrylic, polyacrylamide, polystyrene, acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, butadiene rubber, ethylene-propylene-diene rubber, and polyurethane. In a particular embodiment, the plastic material is intended to contain only hydrolyzable plastics such as polyester, polyamide, and / or polycarbonate, in addition to plastics such as polyurethane. Materials that have been used in previous technical tasks, for example, those occurring within the scope of mattress manufacturing or chemically treated, such as vulcanized natural rubber, are also considered plastics within the scope of the present invention, but lignin, i.e., wood, is not. Plastics can, in some cases, contain other substances depending on their original intended use, such as plasticizers, bactericidal substances, antioxidants, such as stabilizers against ultraviolet light, flame retardants, dyes, or residues of polymerization initiators. Plastics include those made not only from petroleum-based starting products but also within the scope of the concepts of sustainability and renewability, within the scope of chemical synthesis from next-generation raw materials, or within the scope of microbiological processes by appropriately engineered enzymes or production organisms. The mixture containing plastic mentioned at the beginning can be either a mixture of pure plastics or a mixture containing one or more non-plastics such as metals, ceramics, glass, etc.Preferably, one or more plastics, including non-plastics in such a mixture, account for a relatively large proportion, e.g., at least 67%, at least 75%, at least 80%, at least 90%, at least 95%, at least 98%, or at least 99% with respect to mass or volume. It is preferred that there are no non-plastics in the plastic material, and methods for reducing non-plastics are known to those skilled in the art, e.g., manual removal of non-plastics, magnetic removal of magnetic metals or metal alloys, or separation of plastics from other materials of similar density, in some cases, by density difference of materials of different densities, e.g., by means of a wind sieve or a rocking device or a vibrating device. Within the plastic material, polyurethane accounts for the largest mass proportion, preferably more than 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95%, and is thus the overwhelming main component. For example, discarded polyurethane mattresses often contain a correspondingly small proportion of polyethylene or polypropylene derived from the skin material.

[0009] The plastic material used in this method comprises polyurethane and, optionally, further one or more hydrolyzable plastics selected from polyester, polyamide or polycarbonate, or consists of polyurethane and, optionally, further polyester, polyamide or polycarbonate and / or mixtures thereof. According to a particular embodiment, the plastic material consists of polyurethane or a polyurethane mixture, or consists of polyurethane and a polyester or polyester mixture, such as polyethylene terephthalate or a polyethylene terephthalate mixture, or consists of a polyurethane / polyolefin composite material, the proportion of polyurethane in the composite material preferably being at least 50% by weight. Within the hydrolyzable plastic, the polyurethane occupies the largest mass proportion, preferably more than 60%, for example at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95%, and is thus the predominant main component. For example, the plastic material is a mattress or waste from mattress production, and the raw material contains polyurethane as a hydrolyzable component. In that case, the polyurethane can in particular be present as a foam, and within the scope of the present invention, there is the particular advantage that a starting material of high volume (i.e. a foam that can be compressed to a certain extent but always attempts to occupy a large volume and thus requires a correspondingly dimensioned first line and reaction vessel) is reacted in the presence of a reaction medium of relatively small volume, and the volume obtained after the corresponding pressure and heat treatment is significantly reduced. That is to say, substantially, a bulky solid, i.e. a foam, is converted into a more easily handleable form in which the liquid proportion is significantly larger and the volume is smaller, thereby solving the major problems of the polyurethane waste and recycling industries.

[0010] One aspect of the present invention relates to a continuous process for reacting a plastic material comprising at least one hydrolyzable plastic, the process comprising the following steps: a reaction mixture which is present as a solid and comprises a polyurethane, and further comprises an aqueous medium, wherein the mass ratio of water of the aqueous medium to the polyurethane in the reaction mixture is 0.6 to 1 or less; providing a reaction mixture; further, conveying the reaction mixture by means of a first screw conveyor arranged in a first line to a filling opening designed as a pressure lock of a reactor which tapers in the conveying direction at at least one end region; further, conveying the reaction mixture to an end region of the reactor by means of a reactor screw conveyor arranged in the reactor at a temperature of 180 °C to 270 °C and a pressure of > 1 bar to 60 bar; further, transferring the reaction mixture thus pressure- and heat-treated in the end region of the reactor to a second line via a discharge opening designed as a pressure lock; further, conveying the pressure- and heat-treated reaction mixture by means of a second screw conveyor arranged in the second line; further, providing an evaporation zone in the second line at a temperature higher than the temperature in the reactor; further, removing gaseous components via at least one degassing point in the evaporation zone and obtaining a reaction mixture which has been pressure- and heat-treated and from which the gaseous components have been removed, either in the evaporation zone or downstream of the evaporation zone. In that case, the reaction mixture can be in a state in which the gaseous components have been partially or completely removed.

[0011] The aqueous medium contains or consists of water and can optionally contain reaction additives.

[0012] Optionally, the obtained pressure- and heat-treated reaction mixture can be separated into a liquid phase and the solids contained therein, for example by centrifugation or filtration, and optionally the obtained solids can be dried.

[0013] The mass ratio of water in the aqueous medium to polyurethane in the plastic material is 0.6 to 1 or less, particularly 0.5 to 1 or less, for example 0.45 to 1, so that the polyurethane is present in a large excess with respect to the mass ratio. Larger amounts of the aqueous medium are possible, but surprisingly it has been confirmed that a good reaction rate can be achieved with the above mass ratio. Therefore, it is not necessary to suspend the plastic material in the relevant aqueous medium, and it is sufficient to merely moisten it. Reducing the water consumption is an important advantage in aiming for a circular economy that saves resources.

[0014] At the start of the process, the reaction mixture is conveyed by a first screw conveyor to the filling opening of a reactor designed as a pressure lock. An example of a corresponding pressure lock is a double lock known in the art. A further example is a screw conveyor that conveys while compressing the material, or a screw conveyor that even has a return conveyor element that causes local compression of the conveyed material, which itself forms a pressure barrier and thus functions as a pressure lock. The volume of the reactor can range, for example, from the liter range to the cubic meter range, and even up to the volumes of large-scale technologies of several tens of cubic meters and more.

[0015] After passing through the pressure lock, the polyurethane of the plastic material contained in the plastic material, which initially exists as a solid, and optionally other hydrolyzable plastics present therein, migrate into the liquid phase under the temperature and pressure conditions in the reactor in the presence of an aqueous medium optionally containing reaction additives as the reaction of the hydrolyzable plastics contained therein proceeds. Since the volume of the reaction mixture mainly originates from the plastic material due to the low water content, the volume of the plastic material gradually decreases as it is conveyed towards the discharge opening. Therefore, a reactor that tapers at at least one end region can be used, which advantageously requires less heating power and less space as the tapering progresses and, accordingly, as the volume of the reaction mixture decreases.

[0016] This method is carried out at pressures in the range of >1 bar to 60 bar, i.e., pressures higher than atmospheric pressure of 1 bar, for example 5 - 50 bar, 10 - 40 bar, or 20 - 30 bar, for example, i.e., about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 bar. During the execution of the method, the temperature is in the range of 180 °C to 270 °C, for example 180 °C to 250 °C, for example 190 °C to 245 °C, 200 °C to 240 °C, 210 °C to 235 °C, or 215 °C to 230 °C, for example 185, 190, 200, 210, 215, 220, 225, 230, 235, 240 or 250 °C. Preferably, target temperature and target pressure are set, but it is understandable to those skilled in the art that during the execution of the method, the actual values may deviate from the target values or may fluctuate around the target values, and in some cases, they can be correspondingly controlled or readjusted. The temperature and pressure can be actively adjusted. According to a special development form, only the temperature is actively adjusted, and the pressure occurs passively as an equilibrium pressure based on the then temperature of the aqueous reaction mixture within a predetermined reaction volume. The rate of conveyance from the filling opening to the discharge opening can be adjusted according to the achieved reduction in solids, for example, if optional sampling indicates that there is too much solid in the pressure - and heat - treated reaction mixture, it can be reduced, for example. Non - limiting examples of the duration of pressure and heat treatment are, for example, 1 - 8 hours, for example 1.5 - 6 hours, for example 2 - 4 hours, for example 1, 2, 3, 4, 5, 6, 7 or 8 hours, a time of ±0 - 59 minutes. In that case, for example, the duration of pressure and heat treatment is 45 - 250 minutes, especially 45 - 240 minutes. However, when adapting to the progression of a particular reaction, the length of time can be adjusted accordingly, and it is obvious to those skilled in the art that if the reaction is carried out very rapidly, it can be less than 1 hour, and if the reaction is carried out very slowly, it can be longer than 8 hours. This method is carried out continuously, and in some cases, samples are taken from the reactor to determine the degree of reaction, and the length of time is adjusted accordingly. The reaction is carried out with air blocked. The reaction can be carried out especially under anaerobic conditions.Appropriate measures for creating anaerobic conditions are known to those skilled in the art, for example, expelling oxygen from the aqueous reaction mixture by heating, generating steam, and / or flushing with an inert gas such as nitrogen.

[0017] The taper in the conveying direction of the reactor can be continuous, whereby the cross-section between the filling opening and the discharge opening continuously decreases, for example, linearly decreases. As another alternative, it can be contemplated that the cross-section of the reactor is initially constant downstream of the filling opening. Therefore, after the introduction of the reaction mixture into the reactor, the reaction must first start to proceed, and thus it is considered that less solid volume reduction is expected at the filling opening. In that case, the cross-section of the reactor can be reduced at a certain distance from the filling opening. In fact, surprisingly, even when the proportion of the aqueous medium is small, it has been found that the conversion from solid to liquid starts after a short conveyance in the reactor, which is accompanied by a reduction in the solid volume. Therefore, for example, it can be contemplated that the first 5 - 20%, for example, 10 - 15% of the length of the reactor has a constant cross-section, and the remaining part tapers, for example, linearly tapers. According to one embodiment, the conveying direction in the reactor follows gravity.

[0018] After passing through the reactor, the pressure and heat-treated reaction mixture are transferred to a second line through a discharge opening designed as a pressure lock. At this point, the reaction mixture has a significantly reduced volume fraction of solids, and in some cases, no solids are present, compared to the initially used reaction mixture. Instead, the pressure and heat-treated reaction mixture is a liquid, or a liquid containing solids. Advantageously, thereby, a reduction in the volume of the solids used, which consists of the plastic material present as a solid and optionally other solids, as the goal of the method is achieved. For example, a reduction of up to 95%, up to 90%, or 4 - 50%, for example, 5 - 30%, for example, 7 - 25% or 10 - 15% is possible with respect to the volume of the solids used. A significant reduction is particularly possible with foams.

[0019] Another optional goal of the method is to further use the product obtained within the scope of the reaction. Therefore, in order to provide a more uniform pressure and heat-treated reaction mixture, an evaporation zone at a temperature higher than the temperature in the reactor is provided in the second line. Therefore, the evaporation zone is suitable for removing components whose boiling temperature is higher than the temperature in the reactor but lower than the temperature in the evaporation zone. This is done via one or more degassing locations, where gaseous components having the corresponding boiling temperature are removed. At the degassing location, if necessary, cold traps, vacuum traps, and / or valves or regulating devices for maintaining a pressure gradient known in the art can be used. The removed gaseous components can be put to another use. In the evaporation zone or downstream of the evaporation zone, a pressure and heat-treated reaction mixture from which gaseous components having a boiling temperature higher than the temperature in the reactor have been removed is obtained.

[0020] For an improved reaction, the plastic material is preferably used in a pulverized state, especially if it includes plastics that do not swell in water. In that case, pulverization methods common in the art can be used. For example, in some cases, after previously lowering the temperature to increase brittleness, the plastic material can be cut, torn, shredded into fine flakes, minced, granulated, pulverized, or powdered. Non-limiting examples of the size of the plastic particles used are, especially for porous or plastics with a large surface area, about 0.5 cm 3 ~10 cm 3 (0.5 ml to 10 ml), for example about 1 cm 3 ~5 cm 3 or the plastic particles have a diameter measured at the largest point of at most about 10, 5, 2, 1, 0.5, 0.1, 0.05 or 0.01 millimeters.

[0021] According to one embodiment, it is contemplated that the temperature of the evaporation zone is equal to or higher than the boiling temperature of the nitrogen-containing component and lower than the boiling temperature of the high-boiling component. The corresponding nitrogen-containing component is generated particularly when a nitrogen-containing plastic is included in the plastic material, including the case of polyurethane. The nitrogen-containing component is usually a diamine or its decomposition product or reaction product. By removing these nitrogen-containing components, on the one hand, these can be further used separately, and on the other hand, a more uniform pressure and heat-treated reaction mixture can be provided. In particular, the reaction mixture depleted of nitrogen-containing components or from which nitrogen-containing components have been removed is more suitable for subsequent processing steps, such as pyrolysis.

[0022] In one embodiment, it is contemplated that the temperature of the evaporation zone is from 265°C to 300°C, particularly from 265°C to 280°C, for example from 270°C to 280°C. In these temperature ranges, it has been confirmed that, advantageously, a significant proportion of the nitrogen-containing components can be partially or completely removed from the pressure and heat-treated reaction mixture via at least one degassing point. In particular, it has been confirmed that at a temperature of the evaporation zone from 265°C to 280°C, diaminotoluene can be removed from the reaction mixture in gaseous form via the degassing point. Similarly advantageously, the remaining pressure and heat-treated reaction mixture from which the nitrogen-containing components have been partially or completely removed in this way contains components that boil at higher temperatures. Without intending to be bound by theory, considering the polyurethane present in the initially used reaction mixture, these are thought to be polyols and their decomposition products and / or conversion products.

[0023] In one embodiment, in the second line, a dehydration zone is arranged upstream of the evaporation zone, and it is contemplated that its temperature is higher than the boiling temperature of water and lower than the boiling temperature of the nitrogen-containing component. Thus, gaseous water vapor can be withdrawn through one or more water vapor extraction points in the dehydration zone, thereby reducing the water content of the pressure and heat-treated reaction mixture. This enables the provision of a pressure and heat-treated reaction mixture, which is additionally partially or completely dehydrated and, thus, advantageously, exists in a more easily handleable solid form. If necessary, at the water vapor extraction point, a cold trap, a vacuum trap, and / or a valve or regulating device for maintaining a pressure gradient, known in the art, can be used.

[0024] The pressure in the second line can correspond to the pressure in the reactor or atmospheric pressure. In the first case described, an additional pressure lock can be provided at the end of the second line to transition to atmospheric pressure. In the last case described, the pressure is reduced to atmospheric pressure through the extraction opening of the reactor designed as a pressure lock. As another option, one or more additional pressure locks can be used between the extraction opening, which is itself designed as a pressure lock, and the end of the second line to reduce the pressure stepwise.

[0025] According to one embodiment, in the second line where atmospheric pressure prevails, the temperature in the second line corresponds to at least the boiling point of water at the corresponding atmospheric pressure. This advantageously enables the reduction of the water content by providing a dehydration zone having at least one degassing point. In one development, it is contemplated that the temperature of the dehydration zone is lower than the boiling temperature of the nitrogen-containing component, in which case the dehydration zone is followed by an evaporation zone at a temperature higher than the boiling temperature of the nitrogen-containing component, and the nitrogen-containing component can be withdrawn from the pressure and heat-treated reaction mixture from which water has been partially or completely removed through one or more corresponding degassing points in the evaporation zone.

[0026] According to one embodiment, the volume ratio of the solid medium to the aqueous medium in the reaction mixture supplied to the first line is from 100:1 to 5:1, for example from 75:1 to 10:1, from 30:1 to 20:1, for example 25:1. In this regard, it can be seen that the plastic material is not mainly an aqueous medium in which the solid (and possibly still another solid) is suspended, but rather is composed of a plastic material that is merely wetted with a significantly smaller amount of aqueous medium for the majority of the volume. For example, it can be contemplated that 0.05 to 0.2 parts by volume of the aqueous medium are provided per volume of the polyurethane foam, or per volume of the solid. Thus, at the start of the reaction, only the plastic material wetted with the aqueous medium, i.e., substantially only the solid wetted with the reaction medium, is present in the reaction mixture, and as the conveyance in the conveyance direction proceeds, the solid with a large required volume is transferred by the reaction to the liquid phase with a small required volume.

[0027] According to a special embodiment, the ratio of the cross-sectional area of the reactor before tapering to the cross-sectional area of the largest tapering can be 10:1, in particular 5:1, in particular 2:1. Advantageously, this takes into account the expected reduction in the volume of the solid.

[0028] According to one embodiment, it is contemplated that the obtained pressure and the heat-treated reaction mixture are introduced directly or indirectly into a pyrolysis facility to perform pyrolysis. The principle of pyrolysis itself is known and is usually based on the thermochemical conversion of substances under the exclusion of external oxygen in a temperature range of 150°C to 800°C. Within the scope of the method described herein, the maximum temperature in the reactor or in a second line downstream is preferably the lower limit of the temperature range, for example, in a temperature range of 265°C to 800°C. This is, for example, a temperature range of 265°C to 500°C, or 300°C to 500°C. Another example of the temperature range is in the range of 700°C to 800°C, particularly 750°C to 800°C, which is suitable for decomposing calcium carbonate present in the plastic material into calcium oxide and carbon dioxide, and thus for providing pyrolysis coke with little or no calcium carbonate as a pyrolysis product. The pyrolysis treatment is more preferred than using the obtained pressure and the heat-treated reaction medium. Considering that it substantially contains polyol and possibly conversion products, additional washing or separation steps are required to ensure sufficient quality for further use. In contrast, in pyrolysis, monomers of polyol, which are considered to have a higher quality purity compared to polyol, can be advantageously obtained.

[0029] According to a preferred embodiment, the pressure and the heat-treated reaction mixture introduced directly or indirectly into the pyrolysis plant is a reaction mixture in which gaseous components having a boiling temperature lower than the temperature of the evaporation zone have been partially or completely removed beforehand. In particular, according to the embodiments described herein, it is possible to supply a reaction mixture having a low proportion of nitrogen-containing components or not containing such components for pyrolysis. Thereby, pyrolysis products can be provided, which can in turn advantageously be used further. In particular, liquid, gaseous, and solid pyrolysis products can be obtained during pyrolysis. With regard to the liquid product, this is pyrolysis oil, which can itself be subjected to cracking, in which case a high proportion of nitrogen-containing components is obstructive. The obtained pyrolysis gas can be used for power generation, and the problem of nitrogen oxide generation is reduced because of the low proportion of nitrogen-containing components. The solid pyrolysis product, which is a type of pyrolysis coke, can be used for various applications. For example, it can be used as a substitute for carbon black or as petroleum coke that can similarly be used for power generation. Therefore, in this case as well, it is advantageous if the nitrogen-containing components are low or not present.

[0030] According to a particularly preferred embodiment, the pressure and the heat-treated reaction mixture introduced directly or indirectly into the pyrolysis facility pass through a dehydration zone before passing through the evaporation zone, and the water content is reduced there, so that the water content is low or water-free.

[0031] According to one embodiment, the reaction additive optionally contained in the aqueous medium is selected from nitric acid, carboxylic acid, urea and / or biomaterials. Good reactions can be achieved using nitric acid. However, when a pressure and heat-treated reaction mixture with a low proportion of nitrogen-containing components is desired, other reaction additives are preferred because nitric acid introduces additional nitrogen. Generally, mineral acids such as hydrochloric acid or phosphoric acid, or mineral bases such as sodium hydroxide, are not very preferred because the chlorine component, phosphorus component, and sodium component are present in the pressure and heat-treated reaction medium, which may have an adverse effect in the case of downstream thermal decomposition or when the obtained thermal decomposition product is used later. In contrast, alternative reaction additives that can achieve good reactions are carboxylic acids, such as straight-chain saturated monocarboxylic acids particularly formic acid, acetic acid, propionic acid, butyric acid or pentanoic acid, hexanoic acid, heptanoic acid, oxalic acid (ethanedioic acid), malonic acid (propanedioic acid), succinic acid (butanedioic acid), glutaric acid (pentanedioic acid), adipic acid (hexanedioic acid), malic acid (2-hydroxybutanedioic acid), tartaric acid (2,3-dihydroxybutanedioic acid), and dicarboxylic acids such as 3-carboxy-2-oxo-pentanedicarboxylic acid (oxalosuccinic acid), propane-1,2,3-tricarboxylic acid, citric acid (2-hydroxypropane-1,2,3-tricarboxylic acid), and isocitric acid (1-hydroxypropane-1,2,3-tricarboxylic acid). Yet another reaction additive is urea. With respect to the total mass of the aqueous medium, the proportion of urea in the aqueous medium is, for example, 1 to 45 mass percent, particularly 1 to 20 mass percent, for example 1 to 10 mass percent, for example 1 to 7 mass percent, for example 1.5 to 5 mass percent, 1.5 to 4 mass percent, 2 to 4 mass percent, 2.5 to 3.5 mass percent, or 3 mass%. Examples of further ranges or further concentrations are 5 to 10 mass percent, 1 mass percent, 5 mass percent, 7.5 mass percent, and 10 mass percent. From the perspective of the ratio of the amount of urea used to the achieved degree of decomposition of the polyurethane, a range of 1 mass% to 10 mass%, for example 2.5 mass% to 10 mass%, for example 2 mass% to 7.5 mass%, for example 3 mass percent to 5 mass percent is preferred.

[0032] According to a particular embodiment, the aqueous medium contains 2.5 to 10% by weight of urea, in which case the pressure and the duration of the heat treatment are preferably 45 to 250 minutes, in particular 45 to 240 minutes. The ratio of the aqueous medium containing urea to the plastic material containing polyurethane can be, for example, 0.2 ml / g to 5 ml / g, in particular 0.4 ml / g to 5 ml / g.

[0033] Furthermore, the reaction additive can be a biomaterial. Within the scope of the present invention, the biomaterial is understood to be plant material, animal material, or microorganism material, for example a complete plant, or a part of a plant such as wood, leaves, stems, roots or seeds, for example horticultural waste or cut grass. Preferably, the biomaterial is plant material. According to a particular embodiment, the biomaterial is wood, in particular shredded wood in the form of, for example, wood chips, wood chips or shredded wood in the form of sawdust. Using plant material, such as wood, after appropriate dehydration in the dehydration zone, a well-flowable solid that is well-suited for conveying, for example by a screw conveyor, is obtained. This makes subsequent use, such as conveying and introducing into a pyrolysis facility, much easier. Thus, the presence of plant material in the reaction mixture results in a considerable improvement. The mass ratio of the plastic material to the biomaterial, in particular plant material, can be, for example, 3:1 to 1.5:1, for example 2:1. In particular, with respect to the total mass of the plastic material and the biomaterial, a mass ratio of one-third or more, for example 33 to 50% by weight, in particular 33 to 45% by weight, for example 34 to 40% by weight, a very well-flowable solid was obtained after passing through the dehydration zone in the pressure and heat-treated reaction medium.

[0034] The aforementioned reaction additives can be used individually or as an arbitrary mixture of two or more of those described above respectively.

[0035] Examples of the mixing ratio of the plastic material and the aqueous medium containing the reaction additive are 2 to 25 liters of the plastic material moistened with at least 0.08 to 1 liter of the aqueous medium. The aqueous medium can contain 3 to 50 mass percent, particularly 4 to 40 mass percent, for example 4 to 20 mass percent of nitric acid, carboxylic acid, dicarboxylic acid, tricarboxylic acid and / or urea. When mixing the biological material, it can be contemplated that the plastic material occupies 55 to 95 volume percent, particularly 67 to 95 volume percent, and correspondingly the biological material occupies 5 to 45 volume percent, particularly 5 to 33 volume percent. The biological material can be mixed with the plastic material and then the aqueous medium is added, or first mixed with the aqueous medium and then with the plastic material, or all three components can be mixed simultaneously.

[0036] As long as the plastic material and / or the hydrolyzable plastic contained therein is a compressible plastic, particularly a foam, the volumes described refer to the uncompressed plastic.

[0037] According to one embodiment, it is contemplated that one or more pressure barriers are arranged in the first line and / or the second line. When forming a pressure gradient, this is advantageously used to prevent the reaction mixture from being conveyed in a direction opposite to the desired conveyance direction.

[0038] According to one embodiment, the reactor screw conveyor in the reactor can extend only in a part of the reactor, for example, in the part of the reaction vessel where solids are still present at a high proportion, with respect to the conveyance direction.

[0039] According to another embodiment, the reactor screw conveyor extends with a corresponding taper in the tapered end region of the reactor, thereby advantageously ensuring the conveyance of the reaction medium towards the discharge opening over the entire conveyance path.

[0040] The conveying speed of the reactor screw conveyor can be controllable. Thereby, advantageously, the possibility of influencing the residence time of the reaction mixture in the reactor is opened up. If there are fewer reactions than initially assumed, for example, the conveying speed can be decreased in order to increase the reaction by increasing the residence time. If the reaction is faster than initially assumed, the conveying speed can be increased to increase the throughput of the reactor.

[0041] According to one embodiment, the water obtained after removing solids from the obtained pressure and heat-treated reaction mixture from which gaseous components have been removed, and / or the water obtained from the gaseous water taken out through the water vapor extraction location is intended to be added to the provided reaction mixture, optionally after adding a reaction additive. Thus, advantageously, a circulation process is carried out in which water from the already used aqueous medium is at least partially returned to the continuous process, thereby reducing resource consumption.

[0042] Another aspect of the present invention relates to an apparatus for carrying out the methods described herein. The apparatus comprises a first line with a first screw conveyor disposed therein, the first line leading to a reactor via a filling opening designed as a pressure lock, a reactor screw conveyor being disposed within the reactor, the reactor, tapered at least at one end region, leading via a discharge opening designed in an expression-like manner (Ausdrucksweise) to a second line with a second screw conveyor disposed therein, the second line being provided with an evaporation zone which can be set to a temperature higher than that within the reactor, the second line having a degassing location in the evaporation zone where gaseous components can be removed from the second line. Thus, such an apparatus is suitable for conveying a reaction mixture as described herein, i.e., a reaction mixture comprising a plastic material present as a solid and containing polyurethane, and further an aqueous medium containing a reaction additive for wetting the plastic material, via the first screw conveyor of the first line to a filling opening designed as a pressure lock of a reactor with at least one end region tapered. After entering the reactor for the reaction mixture via the filling opening, the reaction mixture is exposed to the pressure and temperature conditions prevailing therein and reacts, and can be transferred to the second line via a discharge opening designed as a pressure lock in the end region of the reactor. The pressure- and heat-treated reaction mixture can be conveyed by the second screw conveyor disposed in the second line to the evaporation zone, where gaseous components can be removed via at least one degassing location. The pressure- and heat-treated reaction mixture depleted of gaseous components in this way can be removed, for example, after further conveyance in the second line for pyrolysis treatment, or can be directly fed, for example, to a pyrolysis facility optionally indicating an expansion of the apparatus described herein.

[0043] In another embodiment of the apparatus, in the second line, a dehydration zone is arranged upstream of the evaporation zone, the temperature of the dehydration zone is higher than the boiling temperature of water and lower than the boiling temperature of the nitrogen-containing components, and in the dehydration zone, gaseous water can be removed through the water vapor extraction point. After the water vapor is removed, from the pressure remaining in the second line and the reaction mixture that has been heat-treated and depleted of water or had water removed, next, in the evaporation zone, the remaining gaseous components, in particular the gaseous nitrogen-containing components, are partially or completely removed. The remaining reaction mixture, which has been pressure- and heat-treated, depleted of water or had water removed, and depleted of or had other gaseous components removed, can also be taken out and, for example, directly or indirectly fed to pyrolysis.

[0044] Reference is also made to the implicit disclosure regarding the apparatus made in connection with the method and vice versa.

[0045] Further advantages, features, and details will become apparent from the following description in which at least one exemplary embodiment is described in detail, with reference to the drawings as necessary. The same, similar, and / or functionally identical parts are designated with the same reference numerals.

Brief Description of the Drawings

[0046]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0047] The drawings are schematic and not necessarily to scale, showing only the important components.

Examples

[0048] Example 1: Preparation of the reaction mixture In the pilot test, as the plastic material, a polyurethane foam mixture obtained from a mattress that had reached the end of its life cycle was used. A mattress with a unit volume weight of about 40 kg per cubic meter was shredded, and the material obtained at that time was a mixture of a standard ether foam, an HR foam, and a viscoelastic foam. 400 g of the material obtained at that time was placed in a 10-liter bucket and filled to about 85%.

[0049] To the shredded material, 100 g of sawdust and 100 g of shredded wood cutting waste were added as biological materials, starting from a density of about 700 kg per cubic meter. The plastic material was mixed with the biological materials, but the bucket was still filled to about 85%.

[0050] As the aqueous medium, plant material was added as a reaction additive, and a pressure and heat-treated 150 ml of reaction medium from a preliminary experiment assuming a pH of 4 in the conversion process was used. This aqueous medium was mixed with the mixture of the plastic material and the biological materials, thereby moistening it. The reaction mixture thus obtained, that is, the mixture of the shredded mattress material and the biological materials moistened with the reaction medium, was about 8.6 l.

[0051] Example 2: Supply to the reactor A Buchi reactor pressure vessel designed with a capacity of 10 l and a maximum pressure of 60 bar was used as the reactor. The prepared reaction mixture was placed in a stainless-steel inner bucket (liner), which was also placed in the Buchi reactor pressure vessel. Subsequently, the Buchi reactor pressure vessel was hermetically sealed with a lid.

[0052] Example 3: Conducting the reaction The purpose of this experiment was to confirm the reduction in the solid ratio by the reaction. The reactor was first heated to a jacket temperature of 260 °C, reached this temperature after about 6 - 10 minutes, then maintained at 260 °C for 1 hour, and subsequently maintained at 240 °C for 2 hours, during which the inside of the reactor reached the equilibrium pressure. Subsequently, the pressure vessel was actively and rapidly cooled to ambient temperature.

[0053] Example 4: Determination of the amount of residual solid After the reaction was completed, the liquid phase of the pressure and heat-treated reaction medium was dropped to confirm the volume of the residual solid. The original components could no longer be recognized in the residual solid. Instead, this was a brownish-black lump, and its volume was determined to be 1.2 l. Therefore, due to the conversion, the volume of the solid decreased to approximately 14% of the starting volume.

[0054] In other experiments using urea solution as the reaction additive, partial to complete liquefaction was confirmed. Therefore, a reduction of 90 - 95% ± 5% in the solid volume can be realistically achieved.

[0055] Example 5: In another experiment, 500 g of shredded mattress material was placed in a Buchi reactor pressure vessel together with 150 mm of water containing 40 g of citric acid and 50 g of 96 percent acetic acid. The mattress material used substantially contained polyurethane foam and the contents of polyethylene and polypropylene.

[0056] This reaction mixture was heated to 260 °C under equilibrium pressure for 60 minutes and then maintained at 250 °C for 120 minutes.

[0057] After cooling the reaction mixture thus pressure and heat-treated, the solid particles consisting of polyethylene / polypropylene floated in the liquid phase due to their low density and could be easily separated mechanically.

[0058] After separating the liquid phase of the pressure and heat-treated reaction mixture, a blackish material remained. When this was dried, a volume reduction of approximately 95% occurred compared to the volume of the plastic material originally used.

[0059] Description of the figures Figure 1 shows a schematic view of reactor 16. A reaction mixture containing a plastic material present as a solid and comprising at least one polyurethane, and further an aqueous medium optionally containing reaction additives, is filled into first line 10 via a filling funnel not shown in detail. In line 10, the reaction mixture is conveyed by first screw conveyor 12 to filling opening 14 of reactor 16 designed as a pressure lock, and introduced into reactor 16 through the filling opening. The pressure inside reactor 16 is >1 bar to 60 bar at a temperature of 180 °C to 270 °C. The reaction mixture is conveyed towards the end region of reactor 16 by reactor screw conveyor 18 arranged inside reactor 16. Due to the reaction in reactor 16 between the polyurethane and, optionally, other hydrolyzable plastics contained in the plastic material, the volume fraction of the solids in the reaction mixture decreases, so that reactor 16 can taper towards the end region. The reaction mixture is introduced into second line 22 through discharge opening 20 of reactor 16 designed as a pressure lock, and conveyed by second screw conveyor 24 therein. There is an evaporation zone 26 in second line 22, the temperature of which is higher than the temperature inside reactor 16. At this temperature, the gaseous components can be removed from second line 22 through degassing point 28, so that a pressure and heat-treated reaction mixture with correspondingly depleted gaseous components can be conveyed downstream of the discharge opening in second line 22 and can be obtained. Details of, for example, a motor for driving a heating device for heating first screw conveyor 12, second screw conveyor 24, or reactor screw conveyor 18, or reactor 16 or evaporation zone 26 are not shown.

[0060] Figure 2 shows another schematic view of reactor 16 corresponding to reactor 16 shown in Figure 1, additionally having a dehydration zone 30 in second line 22. Dehydration zone 30 is located in front of evaporation zone 26 in the conveying direction of the conveyed reaction mixture. Dehydration zone 30 is designed to have a temperature higher than the temperature inside reactor 16 but lower than the temperature inside the subsequent evaporation zone 26. The temperature inside dehydration zone 30 is selected such that water evaporates under the corresponding pressure and temperature conditions.

[0061] The embodiments and / or their individual elements referred to in this specification can be freely combined with each other. Although the present invention has been illustrated and described in detail by preferred examples, the present invention is not limited by the disclosed examples, and those skilled in the art can derive other variations without departing from the protection scope of the present invention. Therefore, it is obvious that there are numerous possible variations. It is also obvious that the exemplified embodiments are merely examples and should not be construed as limiting the protection scope, applicability, or configuration of the present invention in any way. Rather, the foregoing description and the description of the figures enable those skilled in the art to specifically implement the exemplary embodiments, whereby those skilled in the art can, without departing from the protection scope defined by the claims and their legal equivalents, such as the sufficient description in the specification, know the idea of the disclosed invention and make various changes regarding, for example, the functions or arrangements of the individual elements mentioned in the exemplary embodiments.

Description of Reference Numerals

[0062] 10 First line 12 First screw conveyor 14 Filling opening 16 Reactor 18 Reactor screw conveyor 20 Discharge opening 22 Second line 24 Second screw conveyor 26 Evaporation zone 28 Degassing location 30 Dehydration zone 32 Water vapor extraction location

Claims

1. A continuous process for reacting a plastic material containing polyurethane, comprising the following steps, namely A reaction mixture comprising - a plastic material present as a solid and containing polyurethane, and further - an aqueous medium, wherein in the reaction mixture, the mass ratio of water of the aqueous medium to polyurethane is 0.6 to 1 or less, providing a reaction mixture; Conveying the reaction mixture by a first screw conveyor arranged in a first line to a filling opening designed as a pressure lock of a reactor that tapers in the conveying direction at at least one end region; Conveying the reaction mixture by a reactor screw conveyor arranged in the reactor to an end region of the reactor at a temperature of 180 °C to 270 °C and a pressure of > 1 bar to 60 bar; Transferring, in the end region of the reactor, the reaction mixture thus pressure- and heat-treated through a discharge opening designed as a pressure lock to a second line; Conveying the pressure- and heat-treated reaction mixture by a second screw conveyor arranged in the second line; Providing an evaporation zone in the second line at a temperature higher than the temperature in the reactor; Removing gaseous components through at least one degassing location in the evaporation zone, and obtaining, in the evaporation zone or downstream of the evaporation zone, the reaction mixture that has been pressure- and heat-treated and from which gaseous components have been removed; A method comprising the above steps.

2. The method according to claim 1, characterized in that the temperature of the evaporation zone is equal to or higher than the boiling temperature of the nitrogen-containing component and lower than the boiling temperature of the high-boiling components.

3. The method according to claim 1 or 2, characterized in that the temperature of the evaporation zone is 265 °C to 300 °C.

4. The method according to any one of claims 1 to 3, characterized in that in the second line, a dehydration zone is arranged upstream of the evaporation zone, the temperature of the dehydration zone is higher than the boiling temperature of water and lower than the boiling temperature of the nitrogen-containing component, and gaseous water can be taken out through a water vapor extraction location in the dehydration zone.

5. The method according to any one of claims 1 to 4, characterized in that the atmospheric pressure prevails in the second line and the temperature corresponds to at least the boiling point of water at atmospheric pressure.

6. The method according to any one of claims 1 to 5, characterized in that the volume ratio of the solid to the aqueous medium is from 100:1 to 5:

1.

7. The method according to any one of claims 1 to 6, characterized in that the ratio of the cross-sectional area of the reaction vessel before tapering to the cross-sectional area of the maximum tapering is 10:1, in particular 5:1, in particular 2:

1.

8. The reaction mixture obtained with the acquired pressure and heat-treated and optionally depleted of gaseous components having a boiling temperature lower than the temperature of the evaporation zone is introduced directly or indirectly into a pyrolysis facility for performing pyrolysis, characterized in that the method according to any one of claims 1 to 7.

9. The method according to any one of claims 1 to 8, characterized in that the aqueous medium contains a reaction additive selected from nitric acid, carboxylic acid, dicarboxylic acid, in particular adipic acid, tricarboxylic acid, in particular citric acid, and / or urea and / or biomaterial.

10. The method according to claim 9, characterized in that the reaction additive is plant material.

11. The method according to any one of claims 1 to 10, characterized in that one or more pressure barriers are arranged in the first line and / or the second line.

12. The method according to any one of claims 1 to 11, characterized in that the reactor screw conveyor extends to the tapered end region of the reaction vessel by means of a corresponding taper.

13. - Water obtained after removing the solid from the reaction mixture that has been pressure and heat-treated and from which the gaseous components have been removed, and / or - Water obtained from the gaseous water taken out through the water vapor extraction location, The method according to any one of claims 1 to 12, characterized in that it is added to the reaction mixture provided, optionally after adding a reaction additive.

14. An apparatus for carrying out the method according to any one of claims 1 to 13, comprising a first line (10) with a first screw conveyor (12) arranged therein, said first line leading to a reactor (16) via a filling opening (14) designed as a pressure lock, a reactor screw conveyor (18) being arranged in the reactor (16), the reactor (16) tapering at at least one end region leading to a second line (22) with a second screw conveyor (24) arranged therein via a discharge opening (20) designed as a pressure lock, an evaporation zone (26) being provided in the second line (22) which can be set to a temperature higher than that in the reactor (16), the second line (22) having a degassing point (28) in the evaporation zone (26) where the gaseous components can be removed from the second line (22).

15. The apparatus according to claim 14, characterized in that in the second line (22), a dehydration zone (30) is arranged upstream of the evaporation zone (26), the temperature of the dehydration zone being higher than the boiling temperature of water and lower than the boiling temperature of the nitrogen-containing components, and in the dehydration zone, gaseous water can be removed via a steam extraction point (32).

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