Method for producing fuel gas and / or synthesis gas

Abstract

The invention relates to a method for producing fuel gas and / or synthesis gas from: - one or more plastic(s) generated as waste; - one or more biopolymer(s) generated as waste; - one or more monosaccharide(s) generated as waste; or - any mixture of these wastes, the method comprising the following steps: a) forming a reaction mixture by mixing the waste or wastes with at least one basic hydrolysis agent or at least one basic hydrolysis agent dissolved in water; b) transporting the reaction mixture through a heated tube reactor (2), operated according to the counter current principle and having an inlet opening (3) and an outlet opening (4), wherein the reaction mixture is transported from the inlet opening (3) to the outlet opening (4) and, in the process, heated in the tube reactor (2) such that a gas flow, which comprises fuel gas and / or synthesis gas or which is fuel gas and / or synthesis gas, and a non-gaseous material fraction are formed from the reaction mixture; and c) drawing off the gas flow from the tube reactor (2) and removing the non-gaseous material fraction from the tube reactor (2).

Description

[0001] Denkgrün Energy and Resources GmbH

[0002] Description

[0003] Process for producing fuel gas and / or synthesis gas

[0004] The invention relates to a process for producing fuel gas and / or synthesis gas from one or more plastics generated as waste, one or more biopolymers generated as waste, one or more monosaccharides generated as waste or any mixture of these wastes.

[0005] Such a process is known, for example, from WO 2005 / 047436 A1. In a gasifier, biomass generated as waste is passed in countercurrent to a mixture of reaction gas and oxygen, wherein the reaction gas comprises, for example, steam and carbon dioxide. The gasifier comprises a drying zone, a pyrolysis zone, a gasification zone, and a combustion zone, as well as a temperature profile ranging from 426°C to 1370°C. The resulting gas mixture consists of hydrocarbons, hydrogen, carbon monoxide, carbon dioxide, steam, and water and is therefore a fuel gas and / or synthesis gas. The resulting solid fraction is discharged. The gas originating from the first gasifier is passed to another gasifier for further processing. In one embodiment, the first gasifier is a rotary kiln, and the second gasifier is an autothermal reformer.

[0006] WO 2010 / 052179 A1 discloses a process for the hydrolysis of polymers containing vinylcarboxamide units. The polymers are heated in an aqueous medium in the presence of acids or bases and thus hydrolyzed. Lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, or barium hydroxide, and preferably an aqueous solution of potassium or sodium hydroxide, is used as the base. An aqueous solution or dispersion is formed from the polymers and the respective hydrolysis agent, which is continuously introduced into a tubular reactor. The temperature in the tubular reactor is 130°C to 250°C. The process produces compounds containing vinylamine units, wherein the degree of hydrolysis is said to be reproducibly adjustable, in particular by adjusting the residence time of the reaction mixture in the tubular reactor.The hydrolyzed polymers, i.e. the compounds containing vinylamine units, serve, for example, as fixing agents, strengthening agents, flocculants or retention agents.

[0007] EP 0 054 871 A1 discloses a process for hydrolyzing cellulose from plant-based raw materials to glucose. The cellulose is impregnated with acid and continuously conveyed through a hydrolysis zone, in which the cellulose is heated to a temperature of over 250°C using high-pressure steam and a sudden increase in pressure. The process preferably takes place in a tubular reactor designed as a loop reactor, through which an endless piston chain is transported.

[0008] Processes of the type mentioned above are generally known in various forms. These processes typically produce pyrolysis gas, pyrolysis oil, and pyrolysis coke, with pyrolysis gas, pyrolysis oil, and pyrolysis coke being produced in approximately equal quantities. Pyrolysis coke is primarily used in metallurgy, and its application range is therefore quite limited. However, pyrolysis gas and pyrolysis oil have a wide range of applications, especially in the chemical industry, and represent interesting valuable materials in this respect. The processes known to date exhibit a low cold gas efficiency, which, as is known, reflects the ratio of the energy content of the resulting product gas to the energy content of the respective liquid or solid energy source before gasification.

[0009] The invention is therefore based on the object of increasing the yield of fuel gas and / or synthesis gas in an energetically favorable manner using a process of the type mentioned above. This object is achieved according to the invention by a process comprising the following sequential steps: a) Forming a reaction mixture by mixing the waste orthe waste with at least one basic hydrolysis agent or at least one basic hydrolysis agent dissolved in water, wherein the basic hydrolysis agent used is potassium hydroxide, sodium hydroxide, potassium carbonate or sodium carbonate or a mixture of at least two of these hydroxides and / or carbonates, i) wherein the waste contains one or more compounds from the group calcium carbonate, calcium hydroxide, magnesium oxide, magnesium hydroxide and magnesium carbonate and / or ii) wherein one or more compounds from the group calcium carbonate, calcium hydroxide, magnesium oxide, magnesium hydroxide and magnesium carbonate are added to the waste in step a).b) transporting the reaction mixture through a heated tubular reactor operated in countercurrent mode, having an inlet opening and an outlet opening, wherein the reaction mixture is transported from the inlet opening to the outlet opening and is heated in the tubular reactor in such a way that a gas stream comprising fuel gas and / or synthesis gas is formed from the reaction mixture.which is fuel gas and / or synthesis gas, and a non-gaseous material fraction are formed, wherein the process is carried out in such a way that, during the process in step b), a temperature of at least 700°C, in particular of at least 800°C, and preferably of at most 1000°C is established at the outlet opening of the tubular reactor, c) withdrawing the gas stream from the tubular reactor and discharging the non-gaseous material fraction from the tubular reactor, wherein the non-gaseous material fraction discharged from the tubular reactor in step c) comprises calcium oxide and / or magnesium oxide and is mixed with water for causticization, so that calcium carbonate and / or magnesium carbonate and potassium hydroxide dissolved in the water and / or sodium hydroxide dissolved in the water are formed. In the process according to the invention, hydrolysis and thermal treatment of the waste take place in a continuously operated tubular reactor under the respectively prevailing pressure.

[0010] The molecules of starting materials containing heteroatoms are broken down by the basic hydrolysis agent into smaller molecules (molecules with significantly lower molar masses). Polymers whose molecules contain heteroatoms are thus depolymerized. In most cases, organic salts (salts of organic compounds), particularly carboxylates (salts of carboxylic acids), and other organic compounds, such as alcohols, are formed. Advantageously, in molecules containing halogen atoms as heteroatoms, the formation of undesirable halogen compounds, such as gaseous hydrogen chloride or organic halogen compounds, is at least substantially prevented. The withdrawn gas stream is therefore free or essentially free of such halogen compounds. Further details on the chemical reactions taking place during hydrolysis are provided in Section 2.1.

[0011] The smaller molecules resulting from hydrolysis are decomposed at lower temperatures (usually below 300°C), primarily into gases that are part of the fuel and / or synthesis gas, and alcohols. This increases the yield of fuel and / or synthesis gas and significantly reduces the formation of organic compounds and solid by-products (e.g., carbon) that are condensable at room temperature, thus resulting in a particularly high cold gas efficiency.

[0012] The alcohols evaporate and / or condense in the tubular reactor—depending on the local temperature and local chemical equilibrium—and act as solvents for the reaction mixture, thereby improving the reaction kinetics. The alcohols thus contribute to the homogenization of the reaction mixture. Some alcohols may be discharged from the tubular reactor. If the alcohols reach a sufficiently high temperature range in the tubular reactor, they are also decomposed into further gases, which also form a component of the fuel and / or synthesis gas. The organic salts, in particular the carboxylates, are also decomposed into gases in step a), which also form components of the fuel and / or synthesis gas.

[0013] Starting materials whose molecules do not contain heteroatoms are not hydrolyzed. These include, in particular, polyolefins, which undergo thermal decomposition at temperatures above approximately 400°C. This process forms short-chain, gaseous organic compounds, particularly alkanes and alkenes. These short-chain, gaseous organic compounds include organic compounds that recondense in the tubular reactor, as well as organic compounds that do not recondense in the tubular reactor, which include, in particular, ethylene, propene, and butenes. The recondensing organic compounds become liquid again in a "colder" area of ​​the tubular reactor, contribute to improving the reaction kinetics, and - if they penetrate into "warmer" areas of the tubular reactor - are further decomposed, in particular also to organic compounds that do not recondense. The non-recondensing organic compounds are discharged as such as part of the gas stream.

[0014] The temperature profile established in the tubular reactor ensures a variety of advantageous chemical processes in the reaction mixture, as described in detail for the exemplary embodiment in Section 1.6. These chemical processes include the aforementioned hydrolysis, subsequent thermal decomposition and steam reforming, as well as combustion and gasification in the final stage. This further increases the yield of fuel gas and / or synthesis gas as well as the cold gas efficiency.

[0015] The non-gaseous fraction is a solid fraction due to the aforementioned temperatures of at least 700°C. Causticization represents a particularly advantageous addition because it allows for the simple recovery of the hydrolysis agent or the production of a hydrolysis agent suitable for the process from the corresponding compounds generated during the process. Therefore, hardly any by-products are produced. The gas stream withdrawn from the tubular reactor thus comprises fuel gas and / or synthesis gas from a manageable group of gases.

[0016] Preferred embodiments of the procedure are discussed below.

[0017] According to a preferred embodiment, the reaction mixture is formed in step a) in a tubular reactor. This allows for a more compact design of the device carrying out the process.

[0018] According to an alternative preferred embodiment, the reaction mixture is formed in step a) in a mixer. This enables the formation of a particularly homogeneous reaction mixture and—depending on the starting material—is particularly advantageous for the subsequent hydrolysis, thereby achieving particularly high yields of fuel and / or synthesis gas.

[0019] Preferably, the process is carried out such that, during the process in step b), a temperature of 130°C to 250°C, in particular 150°C to 200°C, is established at the inlet of the tubular reactor. At such temperatures at the inlet, the process is operated in a particularly energy-efficient manner.

[0020] Furthermore, it is preferred if, in step a), calcium carbonate and / or magnesium carbonate originating from the causticization and / or potassium hydroxide dissolved in water originating from the causticization and / or sodium hydroxide dissolved in water is / are added to the waste.

[0021] A further preferred embodiment is characterized in that the tubular reactor is preheated before the first transport of the reaction mixture according to step b) such that the temperature at the outlet opening is 800°C to 900°C.

[0022] A further preferred embodiment is characterized in that a burner is provided at the outlet of the tubular reactor, by means of which carbon accruing as part of the non-gaseous material fraction in step b) is ignited and combusted under the supply of air and / or oxygen, wherein the tubular reactor is preferably heated with the burner before the initial transport of the reaction mixture according to step b). As a result, the formation of carbon monoxide (a component of synthesis gas) is promoted via the Boudouard equilibrium. The non-gaseous material fraction discharged in step c) is therefore advantageously free or almost free of carbon. This is particularly favorable for the preferably provided causticization.

[0023] In the latter preferred embodiment, an advantageous variant is that the burner is shut down after the carbon has been ignited, and the resulting carbon is burned with a continuous supply of air and / or oxygen, which is provided in particular via the burner. This ensures autothermal operation of the tubular reactor, which is particularly energy-efficient. The burner is shut down in particular by cutting off the fuel supply.

[0024] A further preferred embodiment consists in adding the hydrolysis agent in step a) in the amount stoichiometrically required for a complete hydrolysis reaction or in excess, with the excess preferably being up to 120% of the stoichiometrically required amount. This promotes a high yield of fuel gas and / or synthesis gas.

[0025] Furthermore, it is advantageous if, in step b), the residence time of the reaction mixture in the tubular reactor is 15 minutes to 180 minutes, particularly preferably 30 minutes to 120 minutes. Such a residence time is advantageous for the formation of fuel and / or synthesis gas.

[0026] Preferably, the tubular reactor is a rotary kiln.

[0027] A further preferred embodiment is characterized in that the plastics used which have accrued as waste are selected from the group of polyethylene (PE-LD / PE-LLD and PE-HD), polypropylene (PP), polyvinyl chloride (PVC) and polystyrene (PS), polyethylene terephthalate (PET), polyamides (PA), polycarbonates (PC), polystyrene (PS), polyisobutylene (PIB), polytetrafluoroethylene (PTFE), polyvinyl acetate, polyvinyl alcohol, polyvinyl ether, poly(metha)acrylic acid, polyacrylic acid esters, polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyacrylamide, polyoxymethylenes (POM), polyurethanes (PUR) and other polyolefins,

[0028] - the plastics generated as waste are in particular hollow bodies, such as bottles, particularly preferably PET bottles, or canisters, films, sheets, polystyrene, foams and other plastic packaging or plastic containers.

[0029] It is particularly preferred if the waste used is made of PET flakes or contains them.

[0030] A further preferred embodiment is characterized in that the natural biopolymers used as waste are selected from the group of fatty acids, cellulose, proteins, peptides, polysaccharides, lipids, polyhydroxyalkanoates, cutin, subergin and lignin,

[0031] - the natural biopolymers generated as waste originate in particular from food scraps, paper waste, sewage sludge, slaughterhouse waste, liquid manure or animal excrement.

[0032] A further preferred embodiment is characterized in that the monosaccharides used, which are generated as waste, originate from food residues, for example from not completely emptied fruit juice packages or from fruit waste.

[0033] A further preferred embodiment is characterized in that the waste used comprises or is formed by solid components, wherein the solid components have a sieve diameter of at most 20.0 mm, in particular of at most 15.0 mm, particularly preferably of at most 10.0 mm.

[0034] Further features, advantages and details of the invention will now be described in more detail with reference to the drawing, which schematically shows an embodiment of the invention. Fig. 1 shows a schematic flow diagram of a process and

[0035] Fig. 2 shows a reaction scheme belonging to the process.

[0036] The invention relates to a process for producing fuel gas and / or synthesis gas from plastics, biopolymers or monosaccharides generated as waste or from any combination of these wastes.

[0037] 1. Example of the method

[0038] In the following description, the abbreviations for the plastics polyethylene terephthalate, polyethylene, and polypropylene are used according to the corresponding standards. Thus, polyethylene terephthalate is abbreviated as PET, polyethylene as PE, and polypropylene as PP.

[0039] 1.1 Starting material of the process

[0040] In the exemplary embodiment, fuel and synthesis gas are produced from a bulk plastic mixture consisting primarily of so-called "PET flakes" and small amounts of PE and / or PP particles. This plastic mixture was obtained from plastic waste consisting primarily of empty disposable PET bottles. The disposable PET bottles originate from recycling containers, which may contain other plastic waste in addition to disposable PET bottles, such as plastic canisters made of PE and the like, so that the disposable PET bottles are usually mixed with other plastics.

[0041] Disposable PET bottles are known to have a PET body and a PE or PP screw cap, and can be provided with labels made of paper or plastic, particularly PP. The plastics used to make disposable PET bottles (PET, PE, PP) may contain fillers, which are added, in particular, to improve mechanical properties, for stretching, or for coloring. These fillers primarily include calcium oxide (CaO), calcium carbonate (CaCO3), calcium hydroxide (Ca(OH)2), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), magnesium carbonate (MgCO3), dolomite (CaMg(CO3)2), wood flour, and rock flour.

[0042] In the exemplary embodiment, it is assumed that the materials underlying the PET disposable bottles and any other plastic waste contain at least calcium oxide (CaO) and / or calcium carbonate (CaCOs) and / or calcium hydroxide (Ca(OH)2) as fillers.

[0043] The plastic waste comprising the disposable PET bottles is shredded to produce a mixture of PET fragments ("PET flakes"), PE and / or PP particles, paper particles from labels, and plastic particles from other plastic waste. Using a sinking / floating process, the PET flakes are separated from the mixture, resulting in a suspension containing water, PET flakes, and small amounts of PE and / or PP particles. The PET flakes are dried, and the paper particles are blown out, yielding the plastic mixture of PET flakes and small amounts of PE and / or PP particles that forms the starting material.

[0044] 1.2 General remarks on the procedure

[0045] As Fig. 1 shows, the plastic mixture (in Fig. 1 PET / PE / PP) is introduced into a mixer 1, for example a screw mixer. Furthermore, potassium hydroxide dissolved in water (in Fig. 1 KOH, hereinafter referred to as potassium hydroxide solution) and, if required, as will be explained (see 1.4), calcium carbonate (in Fig. 1 CaCO3) and / or calcium oxide (in Fig. 1 CaO) and / or calcium hydroxide (in Fig. 1 Ca(OH)2) are introduced into the mixer 1. The respective ambient temperature, which is in particular 15°C and 35°C, is preferably present in the mixer 1. The mixer 1 is therefore preferably not temperature-controlled in any way. In mixer 1, a conveyable reaction mixture is formed, which is fed into a heated rotary kiln 2, in which—as will be explained later (see 1.3 and 1.6.1)—among other processes, an alkaline hydrolysis of the PET molecules of the PET flakes with potassium hydroxide takes place. Fig.Figure 2 shows a reaction scheme illustrating the calcium and potassium compounds formed during the process. The reaction scheme does not fully represent the associated chemical reactions that take place, which will be discussed in more detail (see 1.6 and 1.7). The reaction scheme is referred to several times in the following description.

[0046] 1.3 Hydrolysis

[0047] For complete alkaline hydrolysis of the PET molecules, an appropriate amount of potassium hydroxide is required in the reaction mixture. To estimate the amount of potassium hydroxide required for complete alkaline hydrolysis, the reaction occurring during the alkaline hydrolysis of PET (Reaction Equation 1) is considered. The PE and / or PP particles are not involved in the hydrolysis.

[0048] Reaction equation 1 (in Fig. 2 RG1):

[0049] Potassium hydroxide is added as a potassium hydroxide solution, either in the stoichiometrically required amount (the amount required for complete hydrolysis) or in excess, with the excess preferably being up to 120% of the stoichiometrically required amount. Since the potassium hydroxide solution contains water in addition to potassium hydroxide, a correspondingly larger amount of water must be added compared to the required amount of pure potassium hydroxide. The potassium hydroxide solution is preferably a saturated potassium hydroxide solution or contains at least 90% of the maximum soluble amount of potassium hydroxide in water at 20°C.

[0050] The repeating unit underlying PET, CioHsCU, has a molar mass of 192.17 g / mol, and potassium hydroxide (KOH) has a molar mass of 56.11 g / mol. According to the stoichiometric ratio of reaction equation 1, the stoichiometrically required amount of potassium hydroxide is approximately 0.6 grams per gram of PET (calculation: (56.11*2) / 192.17 ~ 0.58 ~ 0.60).

[0051] 1.4 Causticization (chemical principles)

[0052] The potassium hydroxide solution used for alkaline hydrolysis is produced by the chemical reaction known as “caustification” from potassium carbonate (K2CO3) and calcium hydroxide (Ca(OH)2) (reaction equation 2).

[0053] Reaction equation 2 (in Fig. 2: RG2): K2CO3 + Ca(OH)22K0H + CaCC

[0054] As indicated by the two coupled circuits in Fig. 2, the compounds involved in causticization (potassium carbonate (K2CO3) and calcium hydroxide (Ca(OH)2)) are formed during the process, with calcium and potassium being "circulated". Various calcium compounds and various potassium compounds occur in the process. In order to ensure that a sufficient amount of calcium hydroxide (Ca(OH)2) is present for causticization, an amount of calcium carbonate (CaCCE) and / or calcium oxide (CaO) and / or calcium hydroxide (Ca(OH)2) adjusted to the amount of potassium hydroxide contained therein must be made available in the reaction mixture emerging from mixer 1 (Fig. 1). As will be explained later (see 1.6), the calcium hydroxide (Ca(OH)2) required for causticization is provided by calcium carbonate (CaCO3) as well as by calcium oxide (CaO) and calcium hydroxide (Ca(OH)2).

[0055] 1.5 Formation of a reaction mixture

[0056] The plastic mixture introduced into mixer 1 (in Fig. 1 PET / PP / PE) may already contain such a large amount of calcium compounds (CaCO3, CaO, Ca(OH)2) as filler(s) that they provide the amount of calcium hydroxide (Ca(OH)2) required for causticization. In this case, it is not necessary to additionally introduce calcium compounds into mixer 1. If the amount of the said calcium compound(s) contained in the plastic mixture is insufficient in this respect, one or more of these calcium compounds, particularly in powder form, are additionally introduced into mixer 1. Preferably, calcium carbonate (CaCCh) originating from causticization or excess calcium hydroxide (Ca(OH)2) not consumed during causticization is used (Fig. 2: RG2, cf. reaction equation 2 above).

[0057] For initial start-up of the process, additional calcium carbonate (CaCCh) and / or calcium oxide (CaO) and / or calcium hydroxide (Ca(OH)2) originating from one or more other sources can be introduced into mixer 1 (Fig. 1: if required CaO / CaCO3 / Ca(OH)2, Fig. 2: arrow Pi). Furthermore, for initial start-up of the process, potassium hydroxide originating from one or more other sources, in particular as a potassium hydroxide solution, can be introduced into mixer 1.

[0058] Additional calcium carbonate (CaCO3) is practically insoluble in the potassium hydroxide solution and therefore exists almost entirely as a solid. Additional calcium oxide (CaO) is converted into calcium hydroxide (Ca(OH)2) in the potassium hydroxide solution, which is also poorly soluble in the potassium hydroxide solution and therefore precipitates, at least largely, in powder form. Additional calcium hydroxide (Ca(OH)2) is therefore, at least largely, in powder form.

[0059] In mixer 1, a pumpable reaction mixture (suspension) is formed from water, dissolved potassium hydroxide, PET flakes, PE and / or PP particles, and—depending on the filler and additive—calcium carbonate (CaCO3) and / or calcium hydroxide (Ca(OH)2). The reaction mixture is fed from mixer 1 into the aforementioned rotary kiln 2.

[0060] 1.6 Rotary kiln 2 (structure of the rotary kiln 2 and processes in the rotary kiln 2) The rotary kiln 2 is designed in particular in a known manner, has at least one, in particular exactly one, inlet opening 3, at least one, in particular exactly one, outlet opening 4, a burner for heating (not shown) located in the region of the outlet opening 4, in particular a gas burner or an oil burner, as well as grinding media 5 located in its interior, and is rotatable in a likewise known manner about a rotation axis ai. Before the reaction mixture is fed into the rotary kiln 2 for the first time, the rotary kiln 2 is started up. The rotary kiln 2 is preheated with the burner such that a temperature of in particular 800°C to 900°C is established at the outlet opening 4.

[0061] After start-up, the rotary kiln 2 is operated autothermally (for more detailed explanations, see Section 1.6.3), continuously, under the prevailing pressure, and according to the countercurrent principle, so that two separate phases form from the reaction mixture – namely, a gaseous phase consisting of the gases formed (hereinafter referred to as the gas stream) and a phase consisting of the liquid and / or solid components (hereinafter also referred to as the non-gaseous fraction) representing the remaining reaction mixture – and a direct transfer of heat occurs between these separate phases. The rotation axis ai of the rotary kiln 2 is inclined relative to the horizontal (not shown) such that the non-gaseous fraction is transported from the inlet opening 3 to the outlet opening 4 (transport direction according to arrow Ti) and the gas stream is transported towards the inlet opening 3 (transport direction according to arrow T2).Air is supplied via outlet opening 4.

[0062] The reaction mixture originating from mixer 1 is fed through inlet opening 3 into the already preheated rotary kiln 2. Continuous operation of rotary kiln 2 occurs such that a temperature of 130°C to 250°C, in particular 150°C to 200°C, is established at inlet opening 3. During operation of rotary kiln 2, a temperature profile automatically develops between inlet opening 3 and outlet opening 4, with the temperature rising from inlet opening 3 to outlet opening 4, and a temperature of, in particular, 800°C to 900°C being established at outlet opening 4. As will be explained in more detail below, combustion and oxidation processes occur at these temperatures (see Section 1.6.3).By means of a conventional spectroscopic monitoring system through a sight glass located in the area of ​​the outlet opening 4, it can be easily ensured that the combustion and oxidation processes are taking place and that the aforementioned temperature of 800°C to 900°C prevails. During operation, the temperature at the inlet opening 3 can be regulated, if necessary, by means of the amount of air supplied via the outlet opening 4.

[0063] The reaction mixture (non-gaseous material fraction) continuously flows through the rotary kiln 2, subjecting it to the aforementioned temperature profile and thus becoming increasingly heated as it moves through the rotary kiln 2 toward the exit opening 4. Depending on the prevailing temperature, various processes, in particular various chemical reactions, take place in the reaction mixture. To explain these processes, the rotary kiln 2 is formally divided into a drying and hydrolysis zone Zi, a reforming and thermolysis zone Z2, and a combustion and gasification zone Z3. Starting from the inlet opening 3, the reaction mixture first passes through the drying and hydrolysis zone Zi, then the reforming and thermolysis zone Z2, and finally the combustion and gasification zone Z3.The precise location and extent of the zones are automatically established during continuous operation of rotary kiln 2, with neighboring zones overlapping in sections. Since rotary kiln 2 operates continuously, the aforementioned processes occur in parallel (simultaneously) or partially in parallel (simultaneously).

[0064] 1.6.1 Drying and hydrolysis zone Zi

[0065] The drying and hydrolysis zone Zi extends over a temperature range from 130°C to 300°C. In the drying and hydrolysis zone Zi, the aforementioned alkaline hydrolysis takes place according to reaction equation 1.

[0066] Reaction equation 1 (in Fig. 2: RG1): The PET molecules of the PET flakes are subjected to alkaline hydrolysis with the potassium hydroxide from the potassium hydroxide solution. The PET molecules are depolymerized, i.e., "broken down" into molecules with smaller molar masses, forming an organic potassium salt (in Fig. 2: organic potassium salt), namely potassium terephthalate, and an alcohol, namely ethylene glycol (ethane-1,2-diol). Furthermore, water vapor is formed, which originates from the water supplied with the potassium hydroxide solution. The ethylene glycol is partially in gaseous form (boiling point 197°C) and is withdrawn from rotary kiln 2 together with the resulting water vapor as part of the gas stream. The withdrawn ethylene glycol is a product of the process. Part of the ethylene glycol remains in liquid form in the reaction mixture and acts as a solvent for PET, which further homogenizes the reaction mixture and improves the kinetics of the hydrolysis reaction.

[0067] The PE and PP present melt (Note: The melting point of PP is approximately 160°C, while the melting point of PE is approximately 45°C to 145°C, depending on the PE type) and mixes with the ethylene glycol formed and with organic compounds originating from the reforming and thermolysis zone Z2 and recondensing in the drying and hydrolysis zone Zi. Calcium carbonate (CaCCE) and / or calcium hydroxide (Ca(OH)2) remain unchanged. The reaction mixture is present as a viscous mass at the end of the drying and hydrolysis zone Zi.

[0068] The reaction mixture (non-gaseous fraction) transported from the drying and hydrolysis zone Zi to the reforming and thermolysis zone Z2 therefore comprises ethylene glycol, PE, PP, the organic potassium salt (potassium terephthalate), the recondensing organic compounds and - depending on the additive, as mentioned - calcium carbonate (CaCCE) and / or calcium hydroxide (Ca(OH)2).

[0069] 1.6.2 Reforming and thermolysis zone Z2

[0070] The reforming and thermolysis zone Z2 extends over a temperature range of 300°C to 600°C. PE and PP are thermally decomposed (depolymerized, "thermal cracking") starting at approximately 400°C, forming short-chain, gaseous organic compounds, particularly alkanes and alkenes. These short-chain, gaseous organic compounds have such different boiling points that they comprise organic compounds that can be recondensed in the drying and hydrolysis zone Z1, as well as organic compounds that cannot be recondensed in the drying and hydrolysis zone Z1 and therefore remain gaseous there, including, in particular, ethene, propene, and butenes.

[0071] The re-encodeable organic compounds condense at least largely in the drying and hydrolysis zone Zi (corresponds to the recondensing organic compounds mentioned in Section 1.6.1). Furthermore, small amounts of the re-condensable organic compounds can be discharged as part of the gas stream. Organic compounds formed in the reforming and thermolysis zone Z2 and recondensing in the drying and hydrolysis zone Zi penetrate again into the reforming and thermolysis zone Z2 and are decomposed there, particularly into further short-chain organic compounds, so that the aforementioned organic compounds that do not recondense in the drying and hydrolysis zone Zi are gradually formed.

[0072] The non-recondensing organic compounds are discharged as such as part of the gas stream from the rotary kiln 2 or are subjected to steam reforming in the rotary kiln 2, which will be discussed later.

[0073] Ethylene glycol is also thermally decomposed, forming gases, particularly hydrogen (H2), carbon monoxide (CO), ethene and ketones, which are discharged as part of the gas stream or are also subjected to steam reforming.

[0074] At temperatures above approximately 500°C, the organic potassium salt (potassium terephthalate) decomposes into potassium carbonate (K2CO3), gases such as hydrogen, carbon monoxide, and gaseous organic compounds, as well as amorphous carbon (C) (reaction equation 3). Various other, not readily definable, high-boiling organic compounds can also be formed from the organic potassium salt. The gases are discharged from rotary kiln 2 as part of the gas stream or are also subjected to steam reforming.

[0075] Reaction equation 3 (Fig. 2: RG 3):

[0076] — K2CO3 + gases + C + organic compounds

[0077] In the aforementioned steam reforming process, which takes place in the reforming and thermolysis zone Z2, portions of the gaseous organic compounds formed are converted with the available steam to form synthesis gas (= carbon monoxide (CO) and hydrogen (H2)). The synthesis gas is discharged with the gas stream and thus forms another product of the process.

[0078] Calcium carbonate (CaCOs) remains unchanged.

[0079] Calcium hydroxide (Ca(0H)2) ​​decomposes at temperatures of approximately 580°C (reaction equation 4). The resulting steam is discharged from rotary kiln 2 and / or also participates in the steam reforming process.

[0080] Reaction equation 4 (Fig. 2: RG4):

[0081] Ca(OH)2CaO + H2O

[0082] The reaction mixture (non-gaseous fraction) transported from the reforming and thermolysis zone Z2 to the combustion and gasification zone Z3 therefore comprises potassium carbonate (K2CO3), amorphous carbon (C), depending on the additives—as mentioned—calcium carbonate (CaCO3) and / or calcium oxide (CaO), as well as any high-boiling organic compounds. 1.6.3 Combustion and Gasification Zone

[0083] The combustion and gasification zone Z3 extends over a temperature range of 600°C to 900°C. In particular, the temperature is regulated by the air supply such that the potassium carbonate (K2CO3) in the combustion and gasification zone Z3 is present in solid form (Note: The melting point of potassium carbonate is approximately 891°C). In the combustion and gasification zone Z4, the potassium carbonate (K2CO3) remains unchanged, the amorphous carbon (C) is combusted with oxygen supplied from the air supplied via outlet opening 3 (reaction equation 5), any high-boiling organic compounds are combusted, and calcium carbonate (CaCCL) is decomposed into calcium oxide (CaO) and carbon dioxide (CO2) at approximately 800°C (reaction equation 6, Fig. 2: RG 6). Furthermore, the well-known Boudouard equilibrium between carbon dioxide (CO2), carbon monoxide (CO) and glowing carbon (C) is established (reaction equation 7).As is also known, at approximately 680°C carbon monoxide (CO) and carbon dioxide (CO2) are present in approximately equal amounts.

[0084] Reaction equation 5: C + O2CO2

[0085] Reaction equation 6 (Fig. 2: RG 6): CaCO3CaO + CO2

[0086] Reaction equation 7:

[0087] The initial ignition of the carbon required for the combustion reaction according to reaction equation 5 occurs using the previously mentioned burner. After the carbon has been ignited, the burner is shut off, in particular by cutting off the fuel supply. The carbon is burned with a continuous supply of air and / or oxygen. This combustion reaction is exothermic and provides the heat required for the processes in rotary kiln 2 already explained, ensuring autothermal operation after the carbon has been ignited. Carbon dioxide (CO2) and / or carbon monoxide (CO) are discharged from rotary kiln 2 as part of the gas stream. Any calcium oxide (CaO) already introduced into the combustion and gasification zone Z4 as calcium oxide (CaO), as well as any calcium oxide (CaO) formed in the combustion and gasification zone Z4, remain as calcium oxide (CaO).

[0088] 1. 7 Caustification (procedural processes)

[0089] At the end of the rotary kiln 2, i.e., at the end of the combustion and gasification zone Z3, the remaining reaction mixture (non-gaseous fraction) is a powdered, solid fraction of potassium carbonate (K2CO3) and calcium oxide (CaO), which is conveyed out of the rotary kiln 2 via the outlet opening 4 and transported via a transport pipe 8 connected at least essentially airtight to the outlet opening 4 into a water-filled vessel 6, which is open to the environment at its top. The transport pipe 8 is immersed in the water at one end, so that this end is submerged, thereby "sealing" the rotary kiln 2. A water inlet (H2O in Fig. 1) leads to the vessel 6, allowing water to be refilled at any time. In the vessel 6, the calcium oxide (CaO) reacts with the water (H2O) to form calcium hydroxide (Ca(OH)2) (reaction equation 8, Fig. 2: RG8).The resulting calcium hydroxide (Ca(OH)2) reacts further with the potassium carbonate (K2CO3) to form solid calcium carbonate (CaCO3) and potassium hydroxide (KOH), which reacts with water to form a potassium hydroxide solution (KOH) (reaction equation 2, Fig. 2: RG2). Since calcium hydroxide (Ca(OH)2) is significantly more soluble in water than calcium carbonate (CaCO3), a nearly complete precipitation reaction occurs, thus precipitating calcium carbonate (CaCO3).

[0090] Reaction equation 8:

[0091] CaO + H2O Ca(OH)2

[0092] Reaction equation 2:

[0093] K2CO3 + Ca(OH)22 : K0H + CaCO3 In vessel 6, a mixture of potassium hydroxide solution (KOH), solid calcium carbonate (CaCO3) and - depending on the amount of calcium hydroxide (Ca(OH)2) and potassium carbonate (K2CO3) present - calcium hydroxide (Ca(OH)2) or potassium carbonate (K2CO3) is obtained. According to reaction equation 2, unreacted excess calcium hydroxide (Ca(OH)2) remains as solid calcium hydroxide (Ca(OH)2). According to reaction equation 2, unreacted excess potassium carbonate (K2CO3) is dissolved in water together with the potassium hydroxide (KOH).

[0094] The mixture is passed from the vessel 6 into a filter device 7, by means of which the solid phase (calcium carbonate (CaCO3) and any calcium hydroxide (Ca(OH)2)) is separated from the liquid phase (potassium hydroxide solution (KOH) and any dissolved potassium carbonate (K2CO3)).

[0095] The solid phase (calcium carbonate (CaCO3) and any calcium hydroxide (Ca(OH)2)) is preferably washed with water, thereby removing any sulfates, chlorides, and phosphates originating from impurities. The solid phase is fed to mixer 1 and added in the required amount, as already explained (see 1.4).

[0096] The liquid phase (potassium hydroxide solution (KOH) and any dissolved potassium carbonate (K2CO3)) is concentrated if necessary, in particular by evaporating water, and fed to mixer 1 and added in the required amount, as already explained (see 1.3). The concentration is preferably carried out in such a way that a saturated potassium hydroxide solution or a potassium hydroxide solution containing at least 90% of the maximum amount of potassium hydroxide soluble in water at 20°C is formed.

[0097] Any potassium carbonate (K2CO3) introduced into mixer 1 with the potassium hydroxide solution (KOH) reacts in mixer 1 according to reaction equation 2, forming potassium hydroxide (KOH) and calcium carbonate (CaCO3), which are subject to the reactions already explained (see Fig. 2). 1.8 Products of the process

[0098] In the described embodiment, the gas stream withdrawn from the rotary kiln 2 comprises ethylene glycol, water vapor, non-recondensing, gaseous organic compounds (such as ethene, propene and butenes), other gases (for example hydrogen and gaseous organic compounds), carbon dioxide and / or carbon monoxide, ketones and optionally small amounts of the aforementioned gaseous organic compounds that can be recondensed in the rotary kiln 2, but which do not recondense and are "entrained" by the gas stream and are therefore also discharged.

[0099] Further processing of the withdrawn gas stream takes place in a conventional manner, for example, by condensing individual gases and / or by distillation. The respective gases can be utilized for energy or material recovery in a conventional manner. Any discharged, condensable gaseous organic compounds can alternatively be separated by condensation and returned to the rotary kiln 2, in particular to the reforming and thermolysis zone Z2, where they are subjected to the processes described above and are thus decomposed into gases that form further products of the process.

[0100] The entire process preferably runs continuously.

[0101] The invention is not limited to the described embodiment.

[0102] 2 Further process variants

[0103] Different variants of the procedure are discussed below.

[0104] 2.1 Starting materials of the process

[0105] Possible starting materials for the process are plastics generated as waste, natural biopolymers generated as waste (biogenic biopolymers), monosaccharides generated as waste and

[0106] - any mixtures of these wastes. The plastics generated as waste include, in particular, standard plastics (mass plastics), which are known to include polyethylene (PE-LD / PE-LLD and PE-HD), polypropylene (PP), polyvinyl chloride (PVC), and polystyrene (PS). Other plastics generated as waste include, in particular, polyethylene terephthalate (PET), polyamides (PA), polycarbonates (PC), polystyrene (PS), polyisobutylene (PIB), polyvinyl acetate, polyvinyl alcohol, polyvinyl ether, poly(metha)acrylic acid, polyacrylic acid esters, polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyacrylamide, polyoxymethylenes (POM), polyurethanes (PUR), and polyolefins not yet mentioned.

[0107] The plastics that arise as waste are in particular hollow bodies such as bottles or canisters, films, sheets, polystyrene, foams and other plastic packaging or plastic containers.

[0108] The plastics mentioned usually contain fillers, which are in particular calcium and / or magnesium compounds and which primarily include calcium carbonate (CaCOs), calcium hydroxide (Ca(OH)2), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), magnesium carbonate (MgCCh), and dolomite (CaMg(COs)2). The plastics can each contain one or more fillers. The reactions of the magnesium compounds (MgO, Mg(OH)2, MgCOs) are analogous to the reactions of the calcium compounds explained in the exemplary embodiment. In dolomite (CaMg / COs1), both the calcium and magnesium react accordingly. In this respect, dolomite can therefore be understood as a mixture comprising magnesium carbonate (MgCOs) and calcium carbonate (CaCOs).

[0109] Furthermore, the plastics may contain fillers which are not calcium or magnesium compounds, for example quartz flour, wood flour, stone flour, aluminium powder, graphite, glass fibres or glass microspheres.

[0110] Quartz flour, rock flour, and glass fibers are not chemically altered during the process and are therefore discharged with the solid fraction at the outlet opening 4 of the rotary kiln 2, which in generalized form is a tubular reactor (see below), and can be separated in a conventional manner, for example, using the filter device 7 provided in the exemplary embodiment. Wood flour and graphite are decomposed into gases and leave the rotary kiln 2 together with the gas stream. Hydrogen and solid aluminum compounds are formed from aluminum powder. The hydrogen is discharged as part of the gas stream, and the aluminum compounds are discharged as part of the solid fraction.

[0111] The plastics can be free of heteroatoms. This includes, in particular, all polyolefins.

[0112] The plastics may contain heteroatoms, especially oxygen, nitrogen, chlorine, silicon, sulfur, etc. These plastics include, for example, PET, PVC, and PUR.

[0113] Suitable natural biopolymers include fatty acids, cellulose, proteins, peptides, polysaccharides, lipids, polyhydroxyalkanoates, cutin, subergin, and lignin. These come from, for example, food waste, paper waste, sewage sludge, slaughterhouse waste, liquid manure, or animal feces. These biopolymers typically also contain heteroatoms, such as phosphorus in the form of phosphates. The biopolymers found in sewage sludge contain phosphorus as phosphates and nitrogen. Proteins, for example, can contain sulfur.

[0114] Monosaccharides that accrue as waste come from, for example, fruit juice cartons or fruit waste. Monosaccharides are known to contain oxygen atoms.

[0115] During alkaline hydrolysis, molecules of heteroatom-containing starting materials form an organic potassium salt and / or an organic sodium salt, depending on the hydrolysis agent (see below). For molecules containing oxygen atoms, such as PET, alkaline hydrolysis produces an organic potassium salt and / or an organic sodium salt, as well as an alcohol.

[0116] In the case of molecules containing chlorine atoms, such as PVC, potassium chloride and / or sodium chloride as well as the alcohol polyvinyl alcohol can be formed during alkaline hydrolysis via an SN2 reaction - depending on the hydrolysis agent (see below). An alternative reaction pathway for molecules containing chlorine atoms is an elimination reaction, in which an unsaturated organic compound and hydrogen chloride (HCl) are formed. The unsaturated organic compound is discharged with the gas stream. Depending on the hydrolysis agent (see below), hydrogen chloride reacts immediately to form potassium and / or sodium chloride. In the case of molecules containing chlorine atoms, it is thus possible to capture the hydrogen chloride (HCl) formed in the reforming and thermolysis zone Z2 and thus prevent or largely prevent the discharge of hydrogen chloride with the gas stream.The withdrawn gas stream is therefore advantageously free or at least largely free of hydrogen chloride.

[0117] The respective sodium and / or potassium salt(s) formed is / are discharged.

[0118] Molecules containing nitrogen atoms, such as polyurethane, are broken down into alcohol, diamines, and ammonia through alkaline hydrolysis. The formation of undesirable, complex organic nitrogen compounds is prevented or suppressed.

[0119] In the case of molecules containing sulfur atoms, a sulfide is formed by alkaline hydrolysis, which is oxidized to sulfate in the rotary kiln 2 (generally tubular reactor, see below) and washed out in the filter device 7.

[0120] In the case of molecules containing phosphorus atoms, phosphates or apatites are removed in filter device 7. The starting materials can sometimes contain large amounts of water. Sewage sludge, in particular, can consist largely of water. It is preferred if the starting material consists of a maximum of 50% water.

[0121] 2.2 Products of the process

[0122] The extracted gas stream comprises fuel gas and / or synthesis gas, or is fuel gas or synthesis gas. "Synthesis gas" is understood to be a gas mixture containing primarily carbon monoxide and hydrogen. "Fuel gas" is understood to be a gas mixture whose combustible components include compounds in any combination from the group consisting of hydrogen, carbon monoxide, alkenes, alkanes, and alcohols. Furthermore, fuel gas contains non-combustible components, including, in particular, carbon dioxide, nitrogen (when air is used as the gasification agent), and water vapor. The composition of the gas stream, fuel gas, or synthesis gas varies depending on the feedstock used.

[0123] 2.3 Hydrolysis agents

[0124] Suitable hydrolysis agents for alkaline hydrolysis are potassium hydroxide (KOH), sodium hydroxide (NaOH), potassium carbonate (K2CO3), sodium carbonate (Na2CO3), or mixtures thereof. If sodium hydroxide (NaOH) or sodium carbonate (Na2CO3) is used, it is preferred if the maximum temperature in the combustion and gasification zone Z3 is below the melting point of sodium carbonate (Na2CO3), 854°C. The hydrolysis agent can be supplied as an aqueous solution or, if the starting material contains sufficient water, as a solid, in particular as a powder. An example of a starting material that usually contains sufficient water in this regard is sewage sludge. If an aqueous solution is used as the hydrolysis agent, the amount of hydroxide(s) and / or carbonate(s) is preferably such that the hydroxide(s) and / or carbonate(s) are present in at least 90% of the maximum soluble amount at 20°C.In particular, the hydrolysis agent is saturated with the respective hydroxide(s) and / or carbonate(s). The hydrolysis agent is added in the stoichiometrically required amount for a complete hydrolysis reaction or in excess. The excess is preferably up to 120% of the stoichiometrically required amount. The stoichiometrically required amount of hydrolysis agent is determined empirically or analytically. In an analytical determination, the composition of the starting material is analyzed, and the stoichiometrically required amount of hydrolysis agent is subsequently calculated. Whether the hydrolysis agent is present in the stoichiometrically required amount or in excess can be monitored based on the composition of the fuel gas and / or synthesis gas.A change in the composition of the fuel gas and / or synthesis gas, as well as a lower yield of fuel gas and / or synthesis gas—in each case with the same starting material—indicates incomplete hydrolysis. The amount of hydrolysis agent can be adjusted (changed) as needed.

[0125] 2.4 Causticization

[0126] Causticization can also be performed using sodium hydroxide (NaOH), potassium carbonate (K2CO3), or sodium carbonate (Na2CO3), or the corresponding mixtures (see Section 2.3). As is well known, causticization produces the respective hydroxide, i.e., sodium hydroxide (NaOH) or potassium hydroxide (KOH). Depending on the hydrolysis agent, potassium and / or sodium are therefore "recycled."

[0127] If magnesium compounds (derived in particular from the fillers mentioned in the plastics) are present in the starting product, causticization also takes place with the magnesium compounds. Depending on the starting product, calcium and / or magnesium are therefore "circulated", whereby the corresponding calcium or magnesium compounds are formed. The magnesium hydroxide that forms (Mg(0H>2) is decomposed into magnesium oxide (MgO) and water from around 350°C, with the equilibrium being on the side of magnesium oxide (MgO) from around 600°C. In order for causticization to take place, a sufficient quantity of corresponding magnesium compounds must be made available - analogous to that explained in the example for the calcium compounds. If necessary,In addition to the compounds resulting from causticization, the above-mentioned magnesium compounds and / or calcium compounds, as well as a hydrolysis agent, are added from one or more other sources. For example, separately purchased calcium carbonate (CaCO3) can be used.

[0128] 2.5 Tubular reactor and mixer

[0129] The rotary kiln mentioned in the exemplary embodiment is a special tubular reactor. Instead of the rotary kiln, a differently designed, particularly straight, tubular reactor with an inlet and an outlet opening can be used. The tubular reactor is suitable for feeding, mixing, and transporting a reaction mixture, as well as for removing a gas stream and a non-gaseous material fraction. A reaction mixture can thus flow continuously through the tubular reactor. A "straight tubular reactor" is understood to mean a tubular reactor that is not designed as a loop reactor.

[0130] The tubular reactor does not need to be rotatable and can be equipped with suitable internals, designed in a conventional manner, for mixing and transporting the non-gaseous fraction. The grinding media mentioned in the exemplary embodiment can be omitted. However, grinding media are preferably located in the tubular reactor, as these improve the mixing process in the reaction mixture, thus contributing to homogenization, and also comminuting the solids produced at correspondingly high temperatures, thus promoting their discharge from the tubular reactor.

[0131] A mixer upstream of the tubular reactor can be omitted; in this case, the starting materials and hydrolysis agent are fed directly through the inlet of the respective tubular reactor, so that the starting materials and hydrolysis agent are only mixed in the tubular reactor. In this variant, the reaction mixture is thus formed in the tubular reactor.

[0132] 2.6 Operation of the tubular reactor The tubular reactor is operated in such a way that a temperature of 130°C to 250°C, in particular 150°C to 200°C, is established at the inlet of the tubular reactor. The tubular reactor can be operated autothermally according to the countercurrent principle, as explained in the exemplary embodiment, or allothermally according to the countercurrent principle.

[0133] In autothermal operation, exothermic and endothermic reactions occur in parallel, whereby the processes in the tubular reactor are independent of external heat supply.

[0134] In allothermal operation, external heat is supplied, for example, by means of an electric heater. In allothermal operation, in contrast to autothermal operation, no oxidizing agent (oxygen from the air) is fed into the tubular reactor, so that no combustion and gasification zone Z3 is formed in the tubular reactor. The resulting amorphous carbon therefore does not react further according to reaction equations 5 and 7 above. If nothing further is done, the non-gaseous material fraction discharged from the tubular reactor contains amorphous carbon at the appropriate temperature in the tubular reactor. In allothermal operation, water or steam is preferably introduced into the tubular reactor as an oxidizing agent at the outlet of the tubular reactor, forming a synthesis gas (reaction equation 9). Subsequently, the water gas shift reaction (reaction equation 10) takes place, forming carbon dioxide (CO2).Furthermore, the Boudouard equilibrium (reaction equation 7) is established.

[0135] Reaction equation 9: C + H2O CO + H2

[0136] Reaction equation 10: CO + H2O CO2 + H2

[0137] Reaction equation 7: Preferably, the residence time of the reaction mixture in the tubular reactor is 15 minutes to 180 minutes, particularly preferably 30 minutes to 120 minutes.

[0138] The tubular reactor is operated under the prevailing pressure (i.e. no pressurization and no pressure reduction (no vacuum)).

[0139] List of reference symbols

[0140] 1 mixer

[0141] 2 rotary kilns

[0142] 3 Entrance opening

[0143] 4 Exit opening

[0144] 5 grinding media

[0145] 6 . Vessel

[0146] 7 Filter device

[0147] 8 Transport tube ai rotation axis

[0148] Pi . Arrow

[0149] Ti arrow (transport direction)

[0150] T2 arrow (transport direction)

[0151] Zi drying and hydrolysis zone

[0152] Z2 Reforming and thermolysis zone

[0153] Z3 Combustion and gasification zone

Claims

Patent claims 1. A process for producing fuel gas and / or synthesis gas from one or more plastics generated as waste, one or more biopolymers generated as waste, one or more monosaccharides generated as waste or any mixture of these wastes, comprising the following steps: a) forming a reaction mixture by mixing the waste orthe waste with at least one basic hydrolysis agent or at least one basic hydrolysis agent dissolved in water, wherein the basic hydrolysis agent used is potassium hydroxide (KOH), sodium hydroxide (NaOH), potassium carbonate (K2CO3) or sodium carbonate (Na2COs) or a mixture of at least two of these hydroxides and / or carbonates, i) wherein the waste contains one or more compound(s) from the group calcium carbonate (CaCOs), calcium hydroxide (Ca(OH)2), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2) and magnesium carbonate (MgCOs) and / or ii) wherein one or more compound(s) from the group calcium carbonate (CaCOs), calcium hydroxide (Ca(OH)2), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2) and magnesium carbonate (MgCOs) is added to the waste in step a).b) transporting the reaction mixture through a heated tubular reactor (2) operated in countercurrent fashion and having an inlet opening (3) and an outlet opening (4), the reaction mixture being transported from the inlet opening (3) to the outlet opening (4) and being heated in the tubular reactor (2) in such a way that a gas stream comprising fuel gas and / or synthesis gas or which is fuel gas and / or synthesis gas and a non-gaseous material fraction are formed from the reaction mixture. wherein the process is carried out in such a way that, during the process in step b), a temperature of at least 700°C, in particular of at least 800°C, and preferably of at most 1000°C is established at the outlet opening (4) of the tubular reactor (2), c) withdrawing the gas stream from the tubular reactor (2) and discharging the non-gaseous material fraction from the tubular reactor (2), wherein the non-gaseous material fraction discharged from the tubular reactor (2) in step c) comprises calcium oxide (CaO) and / or magnesium oxide (MgO) and is mixed with water for causticization, so that calcium carbonate (CaCO3) and / or magnesium carbonate (MgCO3) and potassium hydroxide (KOH) dissolved in the water and / or sodium hydroxide (NaOH) dissolved in the water are formed.

2. Process according to claim 1, characterized in that the formation of the reaction mixture according to step a) takes place in the tubular reactor (2).

3. Process according to claim 1, characterized in that the formation of the reaction mixture according to step a) takes place in a mixer (1).

4. Process according to one of claims 1 to 3, characterized in that it is carried out in such a way that, during the process in step b), a temperature of 130°C to 250°C, in particular of 150°C to 200°C, is established at the inlet opening (3) of the tubular reactor (2).

5. Process according to one of claims 1 to 4, characterized in that in step a) calcium carbonate (CaCO3) and / or magnesium carbonate (MgCO3) originating from the causticization and / or potassium hydroxide (KOH) dissolved in water originating from the causticization and / or sodium hydroxide (NaOH) dissolved in water is / are added to the waste.

6. Process according to one of claims 1 to 5, characterized in that the tubular reactor (2) is heated before the first transport of the reaction mixture according to Step b) is preheated such that the temperature at the outlet opening (4) is 800°C to 900°C. Method according to one of claims 1 to 6, characterized in that a burner is provided at the outlet opening (4) of the crude reactor (2), by means of which burner, with the supply of air and / or oxygen in step b), carbon accruing as part of the non-gaseous material fraction is ignited and burned, wherein the crude reactor (2) is preferably heated with the burner before the first transport of the reaction mixture according to step b). Method according to claim 7, characterized in that the burner is switched off after igniting the carbon and the accruing carbon is burned with a continuous supply of air and / or oxygen, which in particular takes place via the burner.Process according to one of claims 1 to 8, characterized in that the hydrolysis agent is added in step a) in the amount stoichiometrically required for a complete hydrolysis reaction or in excess, wherein the excess is preferably up to 120% of the stoichiometrically required amount. Process according to one of claims 1 to 9, characterized in that in step b) the residence time of the reaction mixture in the tubular reactor (2) is 15 minutes to 180 minutes, particularly preferably 30 minutes to 120 minutes. Process according to one of claims 1 to 10, characterized in that the tubular reactor (2) is a rotary kiln (2). Process according to one of claims 1 to 11, characterized in that the plastics used which accrue as waste are selected from the group consisting of polyethylene (PE-LD / PE-LLD and PE-HD), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polyamides (PA). Polycarbonates (PC), polystyrene (PS), polyisobutylene (PIB), polyvinyl acetate, polyvinyl alcohol, polyvinyl ether, poly(metha)acrylic acid, polyacrylic acid esters, polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyacrylamide, polyoxymethylenes (POM), polyurethanes (PUR) and other polyolefins, - the plastics generated as waste are in particular hollow bodies, such as bottles, particularly preferably PET bottles, or canisters, films, sheets, polystyrene, foams and other plastic packaging or plastic containers.

13. A method according to claim 12, characterized in that the waste used is formed from or contains PET flakes.

14. A process according to any one of claims 1 to 13, characterized in that the natural biopolymers used as waste are selected from the group consisting of fatty acids, cellulose, proteins, peptides, polysaccharides, lipids, polyhydroxyalkanoates, cutin, subergin and lignin, - the natural biopolymers generated as waste originate in particular from food scraps, paper waste, sewage sludge, slaughterhouse waste, liquid manure or animal excrement.

15. A process according to any one of claims 1 to 14, characterized in that the monosaccharides used which have accrued as waste originate from food residues, for example from incompletely emptied fruit juice packages or from fruit waste.

16. Process according to one of claims 1 to 15, characterized in that the waste used comprises or is formed from solid components, the solid components having a sieve diameter of at most 20.0 mm, in particular of at most 15.0 mm, particularly preferably of at most 10.0 mm.

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