DEVICE AND METHOD FOR THE PYROLYSIS OF FUEL

Description

FIELD OF THE INVENTION

[0001] The invention relates to a device and a method for the pyrolysis of fuel for heating a burner, in particular a burner of a rotary kiln for the cement industry.

[0002] Furthermore, the device according to the invention can comprise a controller which is configured to carry out the method according to the invention. STATE OF THE ART

[0003] The term "pyrolysis" or "pyrolytic decomposition" generally refers to various thermochemical conversion processes in which organic compounds as starting materials are broken down at high temperatures, typically around 500°C, and largely in the absence of oxygen. Due to the high temperatures, chemical bonds in the starting materials can be broken under these conditions, with a deliberate lack of oxygen preventing complete combustion. The term "pyrolysis" therefore refers to technical processes that aim for an incomplete thermochemical conversion of organic compounds as starting materials, whereby the conversion usually does not go beyond pyrolytic decomposition of the organic compounds.

[0004] Pyrolysis is an important precursor to incineration for the recycling of waste materials such as old tires, scrap wood, or plastic. Pyrolytic pretreatment of waste materials can be particularly useful under certain circumstances. In a pyrolysis process for waste recycling, the usually still moist waste materials are first heated inertly and then dried before the actual pyrolysis of the dried waste materials takes place. Pyrolysis coke and ash generally remain as solid pyrolysis residues.

[0005] Gasification must be distinguished from pyrolysis. This also involves a thermo-chemical conversion of organic compounds as starting materials, but the gasification usually goes beyond pyrolysis. In a gasification process for waste recycling, the usually moist waste materials are also first heated to an inert state and then dried before the actual gasification of the dried waste materials takes place. However, the solid gasification residues in the form of coke are at least partially combusted in a gasification process.

[0006] During the gasification of solid gasification residues in the form of coke or solid carbon C(s) with oxygen and / or steam as gasification agent, the following chemical reactions can usually take place, with the gasification products obtained including carbon monoxide CO, carbon dioxide CO 2 , methane gas CH 4 and hydrogen gas H 2 : Reactions during the actual gasification: (1) C(s)+CO 2 = 2 CO (2) C(s)+H 2 O = CO+H 2 (3) C(s)+2 H 2 = CH 4 Reaction due to the high CO content in the gas phase: (4) CO + H 2 O = CO 2 + H 2

[0007] In contrast to pyrolysis, gasification uses a gasification agent containing oxygen, which further oxidizes the starting materials, causing them to burn and produce primarily gaseous gasification products. While pyrolysis also produces gases, pyrolysis is usually aimed primarily at obtaining liquid or solid pyrolysis products, with a typically smaller proportion of gaseous products or pyrolysis gas.

[0008] By means of gasification, a solid fuel, for example in the form of biomass, can be converted into a gaseous secondary fuel, whereby the exhaust gas from the gasification can be further used for various applications such as as fuel gas or as synthesis gas.

[0009] The production of mineral building materials, especially cement clinker, is very energy-intensive. The raw materials used to produce cement include limestone and clay, which often occur as a natural mixture and are then referred to as marl. If necessary, quartz sand and substances containing iron oxide can be added to the initial mixture for cement production to improve sintering. These raw materials are first ground into raw meal and must then be heated to very high temperatures of around 1,450°C until the ground particles partially fuse together at their grain boundaries and what is known as cement clinker is formed during the sintering process. The cement industry has long used rotary kilns for this purpose, which are usually directly heated. With direct heating, the heat is supplied from within the rotary kiln, for example, from a burner.A product located in the rotary kiln is in direct contact with the resulting flue gas.

[0010] In the Austrian cement industry, alternative secondary fuels, so-called substitute fuels, have been used to heat such rotary kilns for some time now. Substitute fuels, or secondary fuels, are fuels obtained from waste, which can be solid, liquid, or gaseous. The share of alternative substitute fuels, for example in the form of non-recyclable plastic waste, scrap tires, and paper fiber residues, also referred to as the "substitute fuel rate," currently amounts to approximately 75% to 85% of the total firing output in the domestic cement industry. However, to operate such rotary kilns, it is currently still necessary to provide the remaining 15% to 25% of the required firing output from fossil primary fuels in the form of coal, heating oil, and / or natural gas. This share of primary fuels is used for auxiliary firing orrequired for flame shaping of the kiln burner of such rotary kilns.

[0011] Currently known gasification systems, such as air-driven, autothermal fluidized-bed gasifiers, must be operated at very high temperatures, typically around 850°C, to gasify, in particular, the solid residues produced during gasification in the form of coke or residues containing solid carbon. The disadvantage is that the entire fuel quantity must be heated to a temperature of approximately 850°C, which leads to an increased air requirement or increased demand for internal fuel for the additional heating of the resulting gasification product in autothermal, air-driven gasification systems.

[0012] For example, DE 693 02 379 T2 discloses a reactor with a circulating fluidized bed, wherein the reactor is operated at a combustion chamber temperature in the range of 800 to 950°C. The circulating fluidized bed reactor is used for the combustion of coal or biofuel and comprises a single combustion chamber, a particle separator downstream of the combustion chamber for separating circulating material from the flue gas extracted from the combustion chamber, and a return duct for returning the separated circulating solid material to the lower region of the combustion chamber. A gas seal is provided in the center of the return duct, between the particle separator and the confluence of the return duct with the lower region of the combustion chamber, to prevent recirculation of gases rising from the combustion chamber to the particle separator located above.The gas seal is formed by several blocking elements arranged one behind the other or one above the other in the return channel, each with offset openings. The blocking elements are arranged in such a way that the circulating mass of solid material separated by the particle separator that accumulates on the blocking elements blocks the blocking elements and forms a gas seal that prevents an upward flow of gas from the lower section of the return channel through the gas seal into the upper section of the return channel toward the particle separator.

[0013] Injection air is injected from outside into the return channel through nozzles arranged between the multiple barrier elements in the return channel. This loosens and moves the blocked solid material accumulated on and between the barrier elements, allowing it to flow in a controlled manner through the openings in the barrier elements into the lower section of the return channel and further into the combustion chamber. By appropriately adjusting the injection air supply between the barrier elements of the gas seal, a controlled flow of the solid material to be returned can be maintained through the gas seal and downwards into the combustion chamber. At the same time, it is ensured that the gas seal remains sufficiently filled with solid material to prevent unwanted recirculation of rising gases from the combustion chamber.The fuel is supplied to the combustion chamber through a single fuel supply line, which flows into the return channel below, i.e. downstream, of the gas seal.

[0014] Furthermore, the calorific value of the resulting fuel gas as a gasification product is comparatively low, which is why, when operating gas-fired rotary kiln burners, a comparatively high overpressure of usually over 1.5 bar must be set in the fuel gas supply to provide the amount of fuel gas required for kiln operation. However, the combination of these pressures and high temperatures of around 850°C is also problematic from an equipment perspective, as simple boiler steels, which are typically used for the manufacture of pressure vessels, lose their strength at these high temperatures. Pressure- and heat-resistant stainless steels are therefore required for the manufacture of pressurized gasification reactors.

[0015] The term "autothermal reaction" or "autothermal process control" refers to those chemical reactions or processes in which at least one exothermic and one endothermic reaction occur in parallel, so that the overall process is independent of external heat input. An important example is coal gasification in the production of syngas, where glowing coal provides the energy for gasification.

[0016] Due to the aforementioned high exhaust gas temperatures of around 850°C and the associated large exhaust gas volumes, the equipment required to use fuel gasification in combination with the primary firing of rotary kilns is, on the one hand, very high and therefore uneconomical. On the other hand, the calorific value of fuel gas obtained as a gasification product from currently known gasification systems, for example, from an air-driven, autothermal fluidized bed gasifier, is too low to be able to substitute the proportion of the required firing thermal output currently supplied in the form of primary fuels for the operation of rotary kilns. Due to the aforementioned disadvantages, currently available fuel gasification systems have not yet succeeded in completely converting the primary firing of rotary kiln burners to the use of substitute fuels alone, if possible without any primary fuel content.

[0017] In contrast to autothermal fluidized-bed gasifiers, a high-pressure reformer reactor is known from DE 2009 032 524 B3, in which product gas can be generated through allothermal gasification of carbon-containing fuels. In such a reformer reactor, the drying, pyrolysis, and steam reforming of the fuel take place simultaneously in a reactor vessel. Fuel enters the reformer reactor via a single feed line, which is located within the reactor vessel above a combustion chamber.Based on the heat pipe reactor known from EP 1 187 892 B1, DE 2009 032 524 B3 proposes implementing a gas filter and a pressure lock as two separate components in a return line intended for the return of particulate gasification residues from the reformer reactor to the combustion chamber of the reformer reactor. These components can be adjusted separately during operation of the heat pipe reformer. The outlet of the gas filter for separated solid particles is connected to the high-pressure side of the pressure lock arranged downstream of the gas filter. The product gas from the reformer reactor is purified in a gas filter.A portion of the recycled solid particles separated from the reformer reactor, together with solid particles that are conveyed from the reformer reactor into the gas filter in a pneumatic conveying line, passes through the gas filter and the pressure lock via the return line running outside the reactor vessel into the combustion chamber, where they are burned to heat the reformer reactor.

[0018] The publication JP H09 59653 A relates to a device and a method for gasifying fuel in the form of car tires. Car tires pass through a lock onto a combustion grate of a fixed-bed furnace located in an upper section of the gasification reactor. Particles that pass through slots in the combustion grate during the combustion of the car tires and downward into a gasification zone below the fixed bed are gasified in the gasification zone with the addition of combustion gas. A perforated plate at the bottom of the gasification zone serves to form the gas supply to the gasification zone as a fluidized bed. The volatile components from the waste or car tires are thermally decomposed and gasified above the combustion grate. A cyclone separator is provided in the product gas line to purify the exhaust gas.The residue from the gas separator, which consists mainly of bound carbon, is fed into the gasification zone via a return line.

[0019] DE 32 28 532 A1 describes an indirectly heated fluidized bed reactor for the gasification and carbonization of carbon-containing solids with the addition of oxygen-containing compounds of alkali and alkaline earth metals as additives. A fluidized bed gasification zone is located above a sieve plate, and above it, separated by another sieve plate, a fluidized bed carbonization zone is located. To gasify solids in this gasification reactor, steam is fed into the fluidized bed, with an overpressure of up to 5 bar being maintained in the gasification zone. A hearth furnace, which is fed with the solid as fuel, is located upstream of the fluidized bed reactor. The solids dried in the hearth furnace pass through a first material line with a material lock into the fluidized bed carbonization zone below, where they are carbonized.Coke from the carbonisation zone is transported into the lower gasification zone of the fluidised bed reactor by means of conveyor systems and a material lock in a second material line, which is also located outside the fluidised bed reactor. OBJECT OF THE INVENTION

[0020] The object of the invention is therefore to overcome the disadvantages of the prior art and to propose a pyrolysis device with which it is possible to replace the currently required proportion of fossil primary fuels for heating a burner, in particular a burner of a rotary kiln for the cement industry, with non-fossil substitute fuels containing the highest possible proportion of biogenic carbon. The purpose of the device according to the invention is therefore to provide product gas that is obtained with a substitute fuel rate of up to 100%, preferably exclusively from secondary fuels and thus without the use of primary fuels, and that can be fed directly to the burner as a gaseous fuel.

[0021] Further objects of the invention are to provide a pyrolysis device wherein the product gas produced also has a comparatively higher calorific value with a reduced fuel requirement than is typically the case with fuel gas from conventional gasification systems. Furthermore, the equipment required to manufacture a pyrolysis device according to the invention is to be reduced compared to known gasification systems such as air-driven, autothermal fluidized-bed gasifiers, in order to be able to provide product gas with high fuel efficiency as economically and environmentally as possible, particularly for firing a rotary kiln.

[0022] Furthermore, one of the objects of the invention is to provide a control system for the operation of a corresponding pyrolysis device and a method for the pyrolysis of fuel for heating a burner. PRESENTATION OF THE INVENTION

[0023] These objects are achieved with a device according to the invention for the pyrolysis of fuel for heating a burner, in particular a burner of a rotary kiln plant, wherein the device for pyrolysis comprises a pyrolysis reactor, a gasification reactor, an air separator arranged between the pyrolysis reactor and the gasification reactor, and a solids separator arranged downstream of the pyrolysis reactor, preferably a centrifugal separator, particularly preferably a cyclone separator, wherein the pyrolysis reactor has a pyrolysis interior with a first fuel supply device into the pyrolysis interior, wherein the gasification reactor has a gasifier interior with a second fuel supply device and with at least one air supply device into the gasifier interior, wherein the gasification reactor is arranged below the pyrolysis reactor in a height direction,and wherein the pyrolysis interior of the pyrolysis reactor is communicatively connected to the gasification interior of the underlying gasification reactor by means of the air classifier arranged between the pyrolysis reactor and the gasification reactor, wherein an outlet of the pyrolysis reactor is provided for pyrolysis gas from the pyrolysis interior, wherein the outlet for pyrolysis gas is fluidically connected to the downstream solids separator, and wherein the solids separator is configured to purify the pyrolysis gas in an operating state of the device and thus generate a purified product gas that can be fed to the burner, wherein the solids separator has a supply line for pyrolysis gas, a product gas line for supplying purified product gas to the burner, and a return line for solid particles separated from the pyrolysis gas, in particular for fine particles,and wherein the supply line for pyrolysis gas is fluidically connected to the outlet of the pyrolysis reactor, wherein the outlet is preferably arranged in an upper interior zone of the pyrolysis reactor, and wherein the return line for fuel return is fluidically connected to the gasifier interior and preferably opens into it.

[0024] Further advantageous embodiments and developments of the invention can be found in the dependent claims and the description. According to the invention, the pyrolysis device comprises a combination of a gasification reactor and a pyrolysis reactor, wherein the gasification reactor is arranged below the pyrolysis reactor. The pyrolysis interior of the pyrolysis reactor is connected to the gasification interior of the gasification reactor below by means of the air classifier arranged between the pyrolysis reactor and the gasification reactor.

[0025] During operation of the pyrolysis device according to the invention, the lower gasification reactor serves to combust and gasify the solid fuel contained therein or supplied thereto at the temperatures of around 850°C, which are usually typical for gasifiers. The operation of the gasification reactor ensures that the temperature is maintained and the pyrolysis device is heated. The resulting gasification product is led upwards as hot exhaust gas through the air classifier into the pyrolysis reactor, where it meets the fuel present in the interior of the pyrolysis reactor. The hot exhaust gas from the gasification reactor cools upon contact with the solid fuel present at ambient temperature in the pyrolysis interior, and heat is transferred between the solid fuel to be pyrolyzed in the pyrolysis interior of the pyrolysis reactor and the exhaust gas rising from the gasification reactor through the air classifier.

[0026] The actual pyrolysis of the supplied solid fuel takes place in the pyrolysis reactor positioned above the gasification reactor. For this purpose, the gasification reactor and the pyrolysis reactor can be fed separately with solid fuel. A high proportion of lightweight plastic films, also known as "fluff," in the supplied fuel can be particularly advantageous for the operation of the pyrolysis reactor.

[0027] The pyrolysis reactor has an outlet for pyrolysis gas from the pyrolysis chamber, which is fluidically connected to the downstream solids separator. The solids separator is designed to remove solid particles from the pyrolysis gas extracted from the pyrolysis reactor during operation of the device, thus producing a purified product gas that can be fed to the burner.

[0028] The positional information used below for parts or components of the pyrolysis device, such as the terms "top," "bottom," "above," "below," "front," "rear," "side," "inside," "outside," and the like, essentially serve to better understand the invention, in particular to indicate the position and arrangement of the corresponding parts or components in conjunction with the following drawings. In any case, such positional information is familiar to the person skilled in the art and does not limit the present invention.

[0029] In a particularly expedient embodiment of the invention, the first fuel supply device and the second fuel supply device in the device can each be configured to convey solid fuels, preferably solid secondary fuels containing solid waste materials, in the operating state of the device, wherein the first fuel supply device is configured to meter a first solid fuel for the pyrolysis reactor into the pyrolysis interior space in the operating state of the device, and the second fuel supply device is configured to meter a second solid fuel for the gasification reactor into the gasifier interior space in the operating state of the device.

[0030] Advantageously, according to this embodiment, fuels, preferably non-fossil secondary fuels, can be individually metered into the pyrolysis reactor and the gasification reactor independently of each other. This allows both the reaction temperatures in the device—i.e., the pyrolysis temperature in the pyrolysis chamber and the gasification temperature in the gasification chamber—as well as the gas quantity and composition of the product gas to be influenced.

[0031] The fuel supply is not limited to a single feed option into the pyrolysis reactor and / or the gasification reactor. Depending on the design of the device, it may also be expedient, for example, to provide two or more first fuel supply devices to meter a first solid fuel for the pyrolysis reactor into the pyrolysis chamber at different locations. In addition or alternatively, it may be expedient, for example, to provide two or more second fuel supply devices to meter a second solid fuel for the gasification reactor into the gasification chamber at different locations.

[0032] A device according to the invention can be used particularly flexibly if at least one air supply device is configured to meter combustion air into the gasifier interior, preferably into a lower interior zone of the gasifier interior as viewed in the vertical direction, when the device is in operation. The metered amount of combustion air can influence the pyrolysis temperature in the pyrolysis interior or the gasification temperature in the gasifier interior, the gas quantity and gas composition of the product gas, as well as the flow velocity in the free cross-section of the air classifier.

[0033] In order to be able to burn and / or gasify solid residues that form during the gasification of the solid waste materials, it can be advantageous if the gasification reactor in the device according to the invention is designed to be pressurized in the operating state of the device and to autothermally gasify the fuel located in its gasifier interior with the supply of combustion air at a gasification temperature of 700°C to 950°C, preferably 750°C to 900°C, wherein the gasification reactor is preferably a fluidized bed gasifier.

[0034] In this embodiment, a device according to the invention can be used in a particularly versatile manner, since, depending on the application, the gasification reactor can be operated at ambient pressure, slightly underpressure, or under pressure during operation. For use as a device for heating a burner, in particular a burner of a rotary kiln for the cement industry, it may be expedient for the gasification reactor of the device to be pressurized during operation in order to obtain a product gas from the device that also already has an overpressure and can thus be fed directly to the burner, ideally without the need for an additional fan.

[0035] In a preferred embodiment of the invention, the gasification reactor can be a fluidized-bed gasifier. Advantageously, in this design, the solid fuels initially lie on a distribution grate, as in a conventional furnace, which serves to distribute the supplied combustion air into the fixed bed of metered-in solid fuel particles within the gasification reactor.

[0036] During operation, a fluidized bed can assume various states. If one starts with a fixed bed through which a fluid or gas flow flows, and then continuously increases this flow, the solid fuel particles are carried by the supplied combustion air flow from the so-called loosening point, the point of minimum fluidization. The corresponding gas velocity at the beginning of fluidization of the fixed bed is referred to as the fluidization velocity.

[0037] If the gas flow is further increased, bubble formation occurs in the fluidized bed; this operating state is also referred to as a steady-state fluidized bed. This state does not change significantly over a relatively wide range of gas velocities. Depending on the particle shape and size of the solid particles, the fluidized bed can retain its bubble-forming character during operation, for example, up to five times the fluidization velocity. Typically, bubble-forming fluidized beds have solids volume fractions of around 20% to 40%.

[0038] However, the gas velocity in this state is usually lower than the individual particle settling velocity. Figuratively, the particles can be described as swarming. The bubbling, or stationary, fluidized bed is characterized by intensive mixing in the vertical direction. Depending on the cross-sectional area of ​​the bed, large-scale circulation flows can develop, with solids usually rising in the center of the fluidized bed and sinking again at the edges. With very large cross-sectional areas, multiple rising and falling zones form. This effect can be further enhanced by specially arranged gas distribution plates to improve fuel mixing into the bottom zone in fluidized bed combustion systems.

[0039] If the fluidization speed is increased, in some processes there is an increasing discharge of fine material, which in the device according to the invention enters the air classifier and optionally further into the downstream pyrolysis reactor.

[0040] A further increase in fluid flow leads to an increased discharge of initially finer particles from the fluidized bed. To recirculate these particles, the invention provides a solids separator, such as an aerocyclone, for solids separation. This solids separator is arranged downstream of the pyrolysis gas outlet of the pyrolysis reactor and is preferably connected to the gasifier interior via a return line for fuel return. This solids separator separates the discharged solids from the gas stream, which are then transported back to the bottom zone of the developing, circulating fluidized bed via the return line during operation.

[0041] The advantage in the technical application of a circulating fluidized bed compared to a bubbling fluidized bed is the comparatively higher gas velocities in the case of operation with a circulating fluidized bed, which allows larger fuel additions during combustion processes.

[0042] The disadvantages of operating a circulating fluidized bed compared to a bubbling fluidized bed are higher equipment costs and higher energy consumption, and thus higher operating costs for the larger blower required in the case of a circulating fluidized bed to blow in the combustion supply air.

[0043] In a further embodiment of the invention, it may also be expedient if, in the device according to the invention, the gasification reactor is configured to be pressurized with an overpressure of 0.5 bar to 20 bar, preferably 0.8 bar to 10 bar, when the device is in operation. As already mentioned, this embodiment can offer the advantage that the product gas generated by the device already has sufficient overpressure upon leaving the device to be fed directly to the burner as fuel without the need for an additional blower that would have to be interposed in the product gas line.

[0044] In order to achieve the most efficient utilization of the fuels used, it can be advantageous in a further embodiment of the invention if, in a device according to the invention, the pyrolysis reactor is designed to pyrolyze the fuel located in its pyrolysis interior together with hot exhaust gas, which can be fed to the pyrolysis reactor from the gasification reactor through the air classifier, at a pyrolysis temperature of at most 600°C, preferably of at most 500°C, particularly preferably of at most 450°C, in the operating state of the device, wherein the pyrolysis reactor is preferably an entrained flow reactor.

[0045] Typical synthesis gas temperatures in currently known gasification systems are usually above 850°C. However, a disadvantage of such temperature control is that at such high gasification temperatures of over 850°C, the resulting exhaust gas must also be heated to the same high gas outlet temperature of over 850°C due to the increased air requirement in autothermal, air-driven gasification systems, which drastically reduces the calorific value of the hot exhaust gas.

[0046] Furthermore, the equipment required to construct and operate a conventional gasification device operating at synthesis gas temperatures above 850°C is higher than that required for a device according to the invention, since simple boiler steels commonly used for the manufacture of pressure vessels lose their strength at these high temperatures. Pressure- and heat-resistant stainless steels are therefore required for the manufacture of pressurized gasification reactors.

[0047] In contrast, the device according to the invention, in which two reactors, namely a gasification reactor and a pyrolysis reactor, are suitably combined with one another, offers the advantage that the combined pyrolysis and drying of the added fuel in the pyrolysis reactor takes place at comparatively moderate pyrolysis temperatures of at most 600°C, preferably of at most 500°C, particularly preferably of at most 450°C.

[0048] This selection of the pyrolysis temperature in the pyrolysis reactor offers the advantage that the product gas from the device according to the invention can be guided such that the purified product gas leaves the device with a gas outlet temperature of no more than 450°C. Thus, significantly higher calorific values ​​can be achieved in the product gas than is the case with conventional gasification devices with synthesis gas exhaust temperatures of over 850°C. From an equipment perspective, this selection of the pyrolysis temperature in the pyrolysis reactor also offers the advantage that, particularly at pyrolysis temperatures of no more than 450°C, simple boiler steels have sufficient strength for the manufacture of the pyrolysis reactor.

[0049] In a preferred embodiment, the pyrolysis reactor can be an entrained-flow reactor. In an entrained-flow gasifier, the fuel can be introduced into the reaction chamber or pyrolysis chamber as dust or paste, for example, via a dedicated burner, allowing the pyrolysis processes to proceed very quickly. This form of fuel supply usually requires appropriate pretreatment of the secondary fuel or the supplied biomass, for example, via a pneumatic fuel supply device, in order to be introduced into the pyrolysis reactor and pyrolyzed there in a very short time.

[0050] In a preferred embodiment of the device according to the invention, the air classifier can have at least one classifier aperture, preferably at least one adjustable classifier aperture, wherein the air classifier is designed to classify, in the operating state of the device, solid particles of the fuel into coarse particles which can pass from the pyrolysis reactor downwards into the gasification reactor against the height direction, and into fine particles which are lighter than coarse particles and which can pass into the pyrolysis reactor upwards in the height direction, wherein in the operating state of the device, a gas velocity in the region of the at least one classifier aperture can preferably be set from 10 m / s to 40 m / s, particularly preferably from 15 m / s to 30 m / s.

[0051] The design of the air classifier with at least one adjustable or adjustable classifier screen offers the advantage that the separation efficiency of the air classifier can be individually adjusted for the respective system output of the device.

[0052] When operating the device, particularly with high fuel throughputs, it can be problematic at high flow velocities within a single separator screen because the upwardly transported bed material of the fluidized bed can no longer fall downwards into the gasifier interior against the flow direction of the rising exhaust gas from the gasification reactor, but is discharged upwards into the pyrolysis interior. With two or more separator screens, fine particles can still fall back into the fluidized bed even at higher flow velocities in the screen cross-sections due to slight pressure fluctuations between the two or more separator screens, which is advantageous. However, in air classifier designs with multiple separator screens, depending on the operating mode, individual separator screens can also become blocked during operation.

[0053] High flow velocities within the at least one separator screen can occur in the operating state of the device, in particular when, for example, a volumetric compressor such as a screw compressor or a rotary blower is provided for supplying the combustion air into the gasification reactor.

[0054] In the device according to the invention, the solids separator has a supply line for pyrolysis gas, a product gas line for supplying purified product gas to the burner, and a return line for solid particles separated from the pyrolysis gas, in particular for fine particles. The supply line for pyrolysis gas is fluidically connected to the outlet of the pyrolysis reactor, the outlet preferably being arranged in an upper interior zone of the pyrolysis reactor, and the return line for fuel return is fluidically connected to the gasifier interior and preferably opens into it. Non-pyrolyzed, light fuel fractions orIn this particularly effective embodiment of the invention, fine particles that are discharged from the pyrolysis chamber of the pyrolysis reactor with the pyrolysis gas during the device's operating state are separated from the pyrolysis gas by the solids separator and recirculated to the gasifier chamber via the return line as recycled fuel. This further increases the fuel yield and the energy efficiency of the device according to the invention.

[0055] The objects mentioned at the outset are also achieved by a method for the pyrolysis of fuel for heating a burner, in particular a burner of a rotary kiln, having the features of claim 8.

[0056] According to the invention, a method for the pyrolysis of fuel for heating a burner, in particular a burner of a rotary kiln, comprises the following steps: Providing a device according to the invention; providing and metering a first solid fuel, preferably a first solid secondary fuel containing solid waste materials, with the first fuel supply device into the pyrolysis interior of the pyrolysis reactor; providing and metering a second solid fuel, preferably a second solid secondary fuel containing solid waste materials, with the second fuel supply device into the gasifier interior of the gasification reactor; providing and metering combustion air with at least one air supply device into the gasifier interior; optionally igniting the solid fuel located in the gasifier interior while simultaneously supplying combustion air to the gasifier interior; setting a gasification temperature in the gasifier interior of 700°C to 950°C, preferably of 750°C to 900°C;Setting an overpressure in the gasifier interior of 0.5 bar to 20 bar, preferably 0.8 bar to 10 bar; guiding hot exhaust gas, which exhaust gas is produced during the gasification of the fuel located in the gasifier interior, from the gasifier interior through the air classifier into the pyrolysis interior of the pyrolysis reactor arranged above the air classifier; heating the solid fuel located in the pyrolysis interior of the pyrolysis reactor by heat transfer as a result of direct contact with the rising hot exhaust gas while simultaneously cooling the hot exhaust gas; setting a pyrolysis temperature in the pyrolysis interior of at most 600°C, preferably at most 500°C, particularly preferably at most 450°C; discharging pyrolysis gas from the pyrolysis interior and separating solid particles from the pyrolysis gas, whereby a purified product gas is obtained which can be fed to the burner;Separating solid particles from the pyrolysis gas in a solids separator, preferably in a centrifugal separator, particularly preferably in a cyclone separator, wherein solid particles separated from the pyrolysis gas, in particular fine particles, are returned to the gasifier interior.

[0057] With regard to the advantages and beneficial effects of the method according to the invention, reference is made to the aforementioned advantages with regard to the device according to the invention. These advantages and effects apply equally to the device according to the invention and to the implementation of the method according to the invention.

[0058] Depending on the application, in a method according to the invention, an identical fuel composition can be selected for the first solid fuel and the second solid fuel, or alternatively, a fuel composition can be selected for the first solid fuel with a larger proportion of plastic, preferably plastic films, than for the second solid fuel.

[0059] Particularly advantageously, in a process according to the invention, a gas velocity can be set in the range of at least one, preferably adjustable, sifter aperture of the air classifier between 10 m / s and 40 m / s, particularly preferably between 15 m / s and 30 m / s, during operation of the device in the air classifier. Depending on the fuel composition and particle size distribution of the supplied solid fuels, stable continuous operation of the process using the device according to the invention can be enabled at these gas velocities in the air classifier.

[0060] At lower gas velocities, for example, less than 10 m / s, which are measured in the air classifier during operation, the gas flow of the rising exhaust gas from the gasification reactor is too low to entrain small or light fine particles from the gasifier interior through the air classifier into the pyrolysis chamber. Even small or light fine particles remain in the gasifier interior. However, under these conditions, the fixed bed of the supplied fuel in the gasifier interior is comparatively compact and is not sufficiently loosened or fluidized, which is why gasification functions inadequately.

[0061] Conversely, at higher gas velocities, for example, greater than 40 m / s, which are measured in the air classifier during operation, the entire fixed bed contents of the solid fuel introduced into the gasifier interior may be undesirably discharged through the air classifier into the downstream pyrolysis chamber. In this case, satisfactory operation of the device according to the method according to the invention is also not possible.

[0062] A process according to the invention can be carried out particularly advantageously if the purified product gas is obtained on leaving the solids separator with an outlet temperature of at most 450°C, preferably of at most 420°C, particularly preferably of at most 400°C, with an overpressure of at least 1.5 bar and preferably with a calorific value of the purified product gas of at least 11 MJ / Nm 3< , preferably at least 13 MJ / Nm 3< , particularly preferably at least 15 MJ / Nm 3< .

[0063] As already stated above, the process according to the invention can achieve higher calorific values ​​of the product gas with lower gas outlet temperatures of at most 450°C than is the case with conventional gasification processes at significantly higher synthesis gas temperatures of over 850°C. According to the invention, a product gas can therefore be obtained particularly advantageously due to the comparatively lower gas outlet temperature of the purified product gas of at most 450°C with comparatively higher calorific values ​​of at least 11 MJ / Nm 3<.

[0064] An overpressure of at least 1.5 bar of the purified product gas provided according to the process has the advantage that the product gas produced can be fed directly to a downstream burner, in particular a burner of a rotary kiln plant.

[0065] Within the scope of the invention, a device according to the invention comprising a controller is also specified, wherein the controller is set up to carry out the following method steps: Dosing a provided first solid fuel, preferably a first solid secondary fuel containing solid waste materials, with the first fuel supply device into the pyrolysis interior of the pyrolysis reactor; Dosing a provided second solid fuel, preferably a second solid secondary fuel containing solid waste materials, with the second fuel supply device into the gasifier interior of the gasification reactor; Dosing provided combustion air with the at least one air supply device into the gasifier interior; Optionally, igniting the solid fuel located in the gasifier interior while simultaneously supplying combustion air to the gasifier interior;Setting a gasification temperature in the carburetor interior from 700°C to 950°C, preferably from 750°C to 900°C, wherein temperature control of the gasification temperature is dependent on a metered quantity of the supplied second solid fuel and a metered quantity of the supplied combustion air into the carburetor interior; Setting an overpressure in the carburetor interior from 0.5 bar to 20 bar, preferably from 0.8 bar to 10 bar, wherein pressure adjustment is dependent on the metered quantity of the supplied combustion air;Leading hot exhaust gas from the gasifier interior through the air classifier into the pyrolysis interior of the pyrolysis reactor arranged above the air classifier, wherein the metered quantity of the supplied second solid fuel and the metered quantity of the supplied combustion air are regulated depending on a temperature of the hot exhaust gas in the air classifier, preferably in the region of at least one classifier aperture of the air classifier;Heating the solid fuel located in the pyrolysis interior of the pyrolysis reactor by heat transfer as a result of direct contact with the rising hot exhaust gas while simultaneously cooling the hot exhaust gas until a pyrolysis temperature in the pyrolysis interior of at most 600°C, preferably of at most 500°C, particularly preferably of at most 450°C, is set, wherein the pyrolysis temperature is regulated as a function of the metered quantity of combustion air supplied to the gasifier interior and as a function of the metered quantity of the first solid fuel supplied;Removing pyrolysis gas from the pyrolysis interior and separating solid particles from the pyrolysis gas by means of a solids separator, whereby a purified product gas with an outlet temperature of at most 450°C, preferably of at most 420°C, particularly preferably of at most 400°C, is obtained at an overpressure of at least 1.5 bar, whereby the outlet temperature of the purified product gas from the solids separator is regulated as a function of the metered quantity of combustion air supplied to the gasifier interior and as a function of the metered quantity of the first solid fuel supplied to the pyrolysis interior, and the pressure is set as a function of the metered quantity of combustion air supplied.

[0066] With this control system, a device according to the invention can be controlled particularly flexibly to convert solid fuels, preferably solid secondary fuels containing solid waste materials, into purified product gas with the highest possible calorific value in the most energy-efficient manner. The gas outlet temperature of the purified product gas can advantageously be controlled by adjusting the amount of combustion air supplied to the gasification reactor's interior.

[0067] In an advantageous development of the device, it can be provided that the control is designed to set a gas velocity in the range of at least one, preferably adjustable, sifter aperture of the air classifier from 10 m / s to 40 m / s, particularly preferably from 15 m / s to 30 m / s, in the operating state of the device in the air classifier, wherein the setting of the gas velocity in the air classifier is dependent on the metered quantity of the supplied combustion air.

[0068] The gas velocity in the area of ​​at least one separator aperture of the air classifier is regulated during operation of the device in such a way that non-pyrolyzed, light fuel components or fine particles return to the pyrolysis interior of the upper pyrolysis reactor, while heavy fuel components or coarse particles pass through the air classifier into the gasifier interior against the flow direction of the gasifier exhaust gas rising in the air classifier, to be burned or gasified again there. SHORT DESCRIPTION OF THE FIGURE

[0069] The invention will now be explained in more detail using exemplary embodiments. The drawings are exemplary and are intended to illustrate the inventive concept, but in no way restrict it or represent it exhaustively.

[0070] It shows: Fig. 1 is a schematic representation of a first embodiment of a pyrolysis device according to the invention. WAYS OF IMPLEMENTING THE INVENTION

[0071] Fig. 1 shows a schematic representation in partial sectional side view of a first embodiment of a pyrolysis device 1 according to the invention, which comprises a pyrolysis reactor 2, an air classifier 3, a gasification reactor 4, and a solids separator 5. The air classifier 3 is arranged between the pyrolysis reactor 2, which here is designed, for example, in the form of an entrained-flow reactor, and the gasification reactor 4, which here is designed, for example, as a fluidized-bed gasifier. The solids separator 5, which here is designed as a centrifugal separator, for example, a cyclone separator, is arranged downstream of the pyrolysis reactor 2.

[0072] The pyrolysis reactor 2 has a pyrolysis interior 21 with a first fuel supply device 20 into the pyrolysis interior 21, wherein the first fuel supply device 20 is symbolized by an arrow 20. Viewed in a height direction H, which corresponds to a positive z-axis direction in a Cartesian coordinate system, the pyrolysis interior 21 can be divided from bottom to top into a lower interior zone 22 and an adjoining upper interior zone 23 of the pyrolysis reactor 2, wherein an outlet opening 28 for pyrolysis gas 29 is provided in the vessel wall of the pyrolysis reactor 2 in the region of the upper interior zone 23. The flow direction of the pyrolysis gas 29 exiting the outlet opening 28 of the pyrolysis reactor 2 during the ongoing operating state of the device 1 is symbolized by an arrow 29.

[0073] The Fig. 1 The wind classifier 3 illustrated here, for example, has two classifying baffles, namely a first classifying baffle 31, which forms a first classifying chamber, and a second classifying baffle 32, which forms a second classifying chamber of the wind classifier 3.

[0074] The gasification reactor 4 has a gasifier interior 41 with a second fuel supply device 40 into the gasifier interior 41, wherein the second fuel supply device 40 is symbolized by an arrow 40. Viewed in the vertical direction H, the gasifier interior 41 can be divided from bottom to top into a lower interior zone 42 and an adjoining upper interior zone 43 of the gasification reactor 4. In the region of the lower interior zone 42 of the gasification reactor 4, i.e., in a lower section of the gasification reactor 4, there are several inlet openings 45 for supplying air from outside into the gasifier interior 41, wherein the direction of the air supply L is symbolized by arrows L. Furthermore, an ash discharge 48 is provided in the lower interior zone 42 for discharging non-combustible ash portion A from the device 1.The ash discharge 48 is symbolized by an arrow 48 in the direction of a schematic collection container for receiving the ash A.

[0075] The upper interior zone 43 of the gasification reactor 4 is open upwards toward the air separator 3. Viewed in the vertical direction H, the gasification interior 41 of the gasification reactor 4 arranged below the air separator 3 is connected in a communicating manner to the pyrolysis interior 21 of the pyrolysis reactor 2, which is arranged above the air separator 3, by means of the air separator 3 arranged between the pyrolysis reactor 2 and the gasification reactor 4.

[0076] During operation of the device 1, exhaust gas 49 from the gasifier interior 41 of the gasification reactor 4 can rise upwards through the air classifier 3 in the vertical direction H according to the direction of arrow 49 and thus reach the pyrolysis interior 21 of the pyrolysis reactor 2.

[0077] The solids separator 5 shown here in the form of a cyclone separator has an interior 51, a supply line 52 for pyrolysis gas 29, a product gas line 53 for purified product gas P, which is as free as possible from solid particles B, and a return line 54 for solid particles B separated from the pyrolysis gas 29, in particular for fine particles F. The supply line 52 for pyrolysis gas 29 is fluidically or flow-wise connected to the outlet 28 of the pyrolysis reactor 2. The return line 54 for fuel return 55, which is symbolized by an arrow 55 in the conveying direction of the returned, separated solid particles B, is fluidically or flow-wise connected to the gasifier interior 41 and also opens into this gasifier interior 41.

[0078] The solids separator 5 is designed to clean the pyrolysis gas 29 of solid particles B in an operating state of the device 1 and thus to produce a cleaned product gas P, which can be fed to an external burner 200, in particular a burner 200 of a rotary kiln plant.

[0079] In Fig.1Reference symbol A denotes the separated ash A, and reference symbol B denotes the solid fuel B or solid particles B of the fuel fed to the device 1. Preferably, secondary fuels containing solid waste materials are used as the solid fuel B. Depending on the individual requirements and availability of fuels, the same fuels B can, for example, be fed to the pyrolysis reactor 2 and the gasification reactor 4. Alternatively, different fuels B or fuels B with a different composition of waste materials can also be added to the pyrolysis reactor 2 and the gasification reactor 4, wherein a first fuel B2 can be provided for feeding into the pyrolysis reactor 2 and a second fuel B4 can be provided for feeding into the gasification reactor 4.

[0080] To illustrate the flow conditions of the gas flow in the ongoing operating state of the device 1, an exemplary flow path 100 of the ascending exhaust gas 49 in the carburetor interior 41 or of the pyrolysis gas 29 in the pyrolysis interior 21 is indicated as a dotted line with arrows 100.

[0081] In addition, in the area of ​​the air classifier 3, exemplary flow paths of solid fuel particles in the ongoing operating state of the device 1 are sketched with dash-dotted lines, wherein the arrow 101 symbolizes a flow path 101 of a coarse particle G, and the arrow 102 symbolizes a flow path 102 of a fine particle F. Coarse particles G refer to comparatively heavier or larger solid particles B, i.e. those solid fuel particles B with a larger equivalent particle diameter or with a larger mass, which sink downwards in the ongoing operating state of the device 1 against the direction of the arrow 101 of the flow path 101 of the ascending exhaust gas 49 or pyrolysis gas 29.

[0082] On the other hand, those comparatively light or small solid fuel particles B are referred to as fine particles F which, during the ongoing operating state of the device 1, are carried upwards in the direction 101 of the flow path 101 with the ascending exhaust gas 49 and pass through the air classifier 3 into the pyrolysis interior 21 or, if necessary, are further discharged from the pyrolysis interior 21 with the pyrolysis gas 29 and must be separated by the solids separator 5 in order to be returned to the gasifier interior 41 via the fuel return 55. LIST OF REFERENCE SYMBOLS

[0083] 1Pyrolysis device 2Pyrolysis reactor; entrained-flow reactor 20(first) fuel supply for the pyrolysis reactor (arrow) 21Pyrolysis interior of the pyrolysis reactor 22Lower interior zone of the pyrolysis reactor 23Upper interior zone of the pyrolysis reactor 28Outlet opening for pyrolysis gas 29Pyrolysis gas (arrow) 3Air classifier 31(first) classifier aperture; classifier chamber 32(second) classifier aperture; classifier chamber 4Gasification reactor; Fluidized bed gasifier 40 (second) Fuel supply for the gasification reactor (arrow) 41 Gasifier interior of the gasification reactor 42 Lower interior zone of the gasification reactor 43 Upper interior zone of the gasification reactor 45 Inlet opening for air supply 48 Ash discharge (arrow) 49 Exhaust gas from the gasification reactor (arrow) 5 Solids separator; centrifugal separator;Cyclone separator 51Interior of the cyclone separator 52Supply line for pyrolysis gas 53Product gas line 54Return line for solid particles 55Fuel return (arrow) 100Flow direction of the pyrolysis gas (arrow) 101Flow direction of coarse particles (arrow) 102Flow direction of fine particles (arrow) 200Kiln burner of a rotary kiln A Ashes B Solid fuel, solid particles B2 (first) Fuel for pyrolysis reactor B4 (second) Fuel for gasification reactor G Coarse particles F Fine particles H Height (arrow) L Combustion air (arrow) P Purified product gas (arrow) x, y, z Axis directions;

Claims

1. Device (1) for the pyrolysis of fuel (B, B2, B4) for heating a burner (200), in particular a burner of a rotary kiln plant, comprising a pyrolysis reactor (2), a gasification reactor (4), an air classifier (3) arranged between the pyrolysis reactor (2) and the gasification reactor (4), and a solids separator (5) arranged downstream of the pyrolysis reactor (2), preferably a centrifugal separator, particularly preferably a cyclone separator, wherein the pyrolysis reactor (2) has a pyrolysis interior (21) with a first fuel feed device (20) into the pyrolysis interior (21), wherein the gasification reactor (4) has a gasifier interior (41) with a second fuel feed device (40) and with at least one air feed device (45) into the gasifier interior (41), wherein the gasification reactor (4) is arranged below the pyrolysis reactor (2) as viewed in a height direction (H), and wherein the pyrolysis interior (21) of the pyrolysis reactor (2) is communicatively connected to the gasifier interior (41) of the gasification reactor (4) below by means of the air classifier (3) arranged between the pyrolysis reactor (2) and the gasification reactor (4), wherein an outlet (28) of the pyrolysis reactor (2) is provided for pyrolysis gas (29) from the pyrolysis interior (21), wherein the outlet (28) is fluidically connected (52) to the downstream solids separator (5), and wherein the solids separator (5) is set up to purify the pyrolysis gas (29) in an operating state of the device (1) and thus to produce a purified product gas (P) which can be fed to the burner (200), wherein the solids separator (5) has a feed line (52) for pyrolysis gas (29), a product gas line (53) for the supply of purified product gas (P) to the burner (200) and a return line (54) for solid particles (B) separated from the pyrolysis gas (29), in particular for fine material particles (F), and wherein the feed line (52) for pyrolysis gas (29) is fluidically connected to the outlet (28) of the pyrolysis reactor (2), wherein the outlet (28) is preferably arranged in an upper interior zone (23) of the pyrolysis reactor (2), and wherein the return line (54) for fuel return (55) is fluidically connected to the gasifier interior (41) and preferably opens into the latter (41).

2. Device (1) according to claim 1, characterized in that the first fuel feed device (20) and the second fuel feed device (40) are each set up to convey solid fuels (B, B2, B4), preferably solid secondary fuels (B, B2, B4) containing solid waste materials, in the operating state of the device (1), wherein the first fuel feed device (20) is set up to meter a first solid fuel (B, B2) for the pyrolysis reactor (2) into the pyrolysis interior (21) in the operating state of the device (1), and the second fuel feed device (40) is set up to meter a second solid fuel (B, B4) for the gasification reactor (4) into the gasifier interior (41) in the operating state of the device (1).

3. Device (1) according to claim 1 or 2, characterized in that the at least one air feed device (45) is set up to meter combustion air (L) into the gasifier interior (41) in the operating state of the device (1), preferably into a lower interior zone (42) of the gasifier interior (41) as viewed in the height direction (H).

4. Device (1) according to one of claims 1 to 3, characterized in that the gasification reactor (4) is set up to be pressurized in the operating state of the device (1) and to autothermally gasify the fuel (B, B4) located in its gasifier interior (41) with a supply (45) of combustion air (L) at a gasification temperature of 700°C to 950°C, preferably from 750°C to 900°C, wherein the gasification reactor (4) is preferably a fluidized bed gasifier.

5. Device (1) according to one of claims 1 to 4, characterized in that the gasification reactor (4) is set up to be subjected to an overpressure of 0.5 bar to 20 bar, preferably from 0.8 bar to 10 bar, in the operating state of the device (1).

6. Device (1) according to one of claims 1 to 5, characterized in that the pyrolysis reactor (2) is set up, in the operating state of the device (1), to feed the fuel (B, B2) located in its pyrolysis interior (21) together with hot flue gas (49), which can be fed to the pyrolysis reactor (2) from the gasification reactor (4) through the air classifier (3), at a pyrolysis temperature of at most 600°C, preferably of at most 500°C, particularly preferably of at most 450°C, wherein the pyrolysis reactor (2) is preferably an entrained-flow reactor.

7. Device (1) according to one of claims 1 to 6, characterized in that the air classifier (3) has at least one classifier aperture (31, 32), preferably at least one adjustable classifier aperture (31, 32), and wherein the air classifier (3) is set up, in the operating state of the device (1), to classify solid particles (B) of the fuel into coarse material particles (G) which can pass from the pyrolysis reactor (2) downwards into the gasification reactor (4) against the height direction (H), and into fine material particles (F) which are lighter than coarse material particles (G) and which can pass upwards in the height direction (H) into the pyrolysis reactor (2), wherein a gas velocity of 10 m / s to 40 m / s, particularly preferably from 15 m / s to 30 m / s, can preferably be set in the region of the at least one classifier aperture (31, 32) in the operating state of the device (1).

8. Method for the pyrolysis of fuel (B) for heating a burner (200), in particular a burner of a rotary kiln plant, the method comprising the following steps of: - providing a device (1) according to one of claims 1 to 7; - providing and metered feeding of a first solid fuel (B, B2), preferably a first solid secondary fuel (B, B2) containing solid waste materials, with the first fuel feed device (20) into the pyrolysis interior (21) of the pyrolysis reactor (2); - providing and metered feeding of a second solid fuel (B, B4), preferably a second solid secondary fuel (B, B2) containing solid waste materials, with the second fuel feed device (40) into the gasifier interior (41) of the gasification reactor (4); - providing and metered feeding of combustion air (L) with at least one air feed device (45) into the gasifier interior (41); - optionally, ignition of the solid fuel (B, B4) in the gasifier interior (41) with simultaneous supply of combustion air (L) into the gasifier interior (41); - setting a gasification temperature in the gasifier interior (41) of 700°C to 950°C, preferably from 750°C to 900°C; - setting an overpressure in the gasifier interior (41) of 0.5 bar to 20 bar, preferably from 0.8 bar to 10 bar; - conducting hot flue gas (49), which flue gas (49) is produced during the gasification of the fuel (B, B4) located in the gasifier interior (41), from the gasifier interior (41) through the air classifier (3) into the pyrolysis interior (21) of the pyrolysis reactor (2) arranged above the air classifier (3); - heating of the solid fuel (B, B2) located in the pyrolysis interior (21) of the pyrolysis reactor (2) by heat transfer as a result of direct contact with the rising hot flue gas (49) and simultaneous cooling of the hot flue gas (49); - setting a pyrolysis temperature in the pyrolysis interior (21) of at most 600°C, preferably of at most 500°C, particularly preferably of at most 450°C; - removal of pyrolysis gas (29) from the pyrolysis interior (21) and separation of solid particles (B, F) from the pyrolysis gas (29), wherein a purified product gas (P) is obtained which can be fed (53) to the burner (200); - separation of solid particles (B, F) from the pyrolysis gas (29) in a solids separator (5), preferably in a centrifugal separator, particularly preferably in a cyclone separator, wherein solid particles (B) separated from the pyrolysis gas (29), in particular fine material particles (F), are returned (55) to the gasifier interior (41).

9. Method according to claim 8, characterized in that an identical fuel composition is selected for the first solid fuel (B, B2) and the second solid fuel (B, B4), or in that a fuel composition is selected for the first solid fuel (B, B2) with a greater proportion of plastic, preferably plastic films, than for the second solid fuel (B, B4).

10. Method according to claim 8 or 9, characterized in that, during operation of the device (1) in the air classifier (3), a gas velocity in the region of at least one, preferably adjustable, classifier aperture (31, 32) of the air classifier (3) of 10 m / s to 40 m / s, particularly preferably from 15 m / s to 30 m / s, is set.

11. Method according to one of claims 8 to 10, characterized in that the purified product gas (P) is obtained at an outlet temperature of at most 450°C, preferably of at most 420°C, particularly preferably of at most 400°C, with an overpressure of at least 1.5 bar and with a calorific value of the purified product gas (P) of at least 11 MJ / Nm3, preferably at least 13 MJ / Nm3, particularly preferably at least 15 MJ / Nm3, when it emerges from the solids separator (5).

12. Device (1) according to one of claims 1 to 7, comprising a control system, characterized in that the control system is set up to carry out the following method steps of: - metering a provided first solid fuel (B, B2), preferably a first solid secondary fuel (B, B2) containing solid waste materials, with the first fuel feed device (20) into the pyrolysis interior (21) of the pyrolysis reactor (2); - metering a provided second solid fuel (B, B4), preferably a second solid secondary fuel (B, B2) containing solid waste materials, with the second fuel feed device (40) into the gasifier interior (41) of the gasification reactor (4); - metering of provided combustion air (L) with the at least one air feed device (45) into the gasifier interior (41); - optionally, ignition of the solid fuel (B, B4) located in the gasifier interior (41) with simultaneous supply of combustion air (L) into the gasifier interior (41); - setting a gasification temperature in the gasifier interior (41) of 700°C to 950°C, preferably from 750°C to 900°C, wherein the gasification temperature is controlled as a function of a metered quantity of the second solid fuel (B, B4) supplied and as a function of a metered quantity of the combustion air (L) supplied into the gasifier interior (41); - setting an overpressure in the gasifier interior (41) of 0.5 bar to 20 bar, preferably from 0.8 bar to 10 bar, wherein the pressure is set depending on the metered quantity of combustion air (L) supplied; - conducting hot flue gas (49) from the gasifier interior (41) through the air classifier (3) into the pyrolysis interior (21) of the pyrolysis reactor (2) arranged above the air classifier (3), wherein a control of the metered quantity of the second solid fuel (B,B4) supplied and a control of the metered quantity of the combustion air (L) supplied are carried out as a function of a temperature of the hot flue gas (49) in the air classifier (3), preferably in the region of at least one classifier aperture (31, 32) of the air classifier (3); - heating of the solid fuel (B, B2) located in the pyrolysis interior (21) of the pyrolysis reactor (2) by heat transfer as a result of direct contact with the rising hot flue gas (49) with simultaneous cooling of the hot flue gas (49) until a pyrolysis temperature in the pyrolysis interior (21) of at most 600°C, preferably of at most 500°C, particularly preferably of at most 450°C, is set, wherein the pyrolysis temperature is controlled as a function of the metered quantity of the combustion air (L) supplied to the gasifier interior (41) and as a function of the metered quantity of the first solid fuel (B, B2) supplied; - discharge of pyrolysis gas (29) from the pyrolysis interior (21) and separation of solid particles (B, F) from the pyrolysis gas (29) by means of a solids separator (5), wherein a purified product gas (P) with an outlet temperature of at most 450°C, preferably of at most 420°C, particularly preferably of at most 400°C, is obtained at an overpressure of at least 1.5 bar, wherein a control of the outlet temperature of the purified product gas (P) from the solids separator (5) is carried out as a function of the metered quantity of combustion air (L) supplied to the gasifier interior (41) and as a function of the metered quantity of the first solid fuel (B, B2) supplied to the pyrolysis interior (21) and the pressure setting is carried out as a function of the metered quantity of combustion air (L) supplied.

13. Device (1) according to claim 12, characterized in that the control system is set up to adjust a gas velocity in the range of at least one, preferably adjustable, classifier aperture (31, 32) of the air classifier (3) of 10 m / s to 40 m / s, particularly preferably from 15 m / s to 30 m / s, in the operating state of the device (1), wherein the gas velocity in the air classifier (3) is set as a function of the metered quantity of combustion air (L) supplied.