Device for drying material and asphalt mixing plant with such a device

Abstract

Device for drying material for an asphalt mixing plant, the device (2, 3) comprising a rotary kiln (9) which can be driven to rotate about a rotational axis (19) and in which the material is dried, the rotary kiln (9) having a material inlet (10) and a material outlet (11), b. a heating unit coupled to the rotary kiln (9) for supplying heat to the rotary kiln (9), the heating unit being designed with a burner (12) having i. a burner housing (27) having a longitudinal axis (26), ii. an air line (16) arranged on the burner housing (27) for supplying air, iii. a swirling element (35) for swirling the air in the burner (12) relative to the longitudinal axis (26), iv. a hydrogen gas line (14) connected to the burner (12) for supplying hydrogen gas into the burner (12), wherein a hydrogen gas nozzle (31) for discharging the hydrogen gas is connected to the hydrogen gas line (14), v. a burner head (41) arranged on the burner housing (27) for generating a burner flame (13), wherein the burner (12) can be operated exclusively by means of hydrogen gas.

Description

[0001] The content of the German patent application DE 10 2021 210 662.5 is incorporated herein by reference.

[0002] The invention relates to a device for drying material and to an asphalt mixing plant with such a device.

[0003] In an asphalt mixing plant, various materials are processed, particularly dried and mixed together. A large portion of the energy required for the subsequent asphalt mixing process occurs when the material for asphalt mixing plants is dried. The material is therefore also heated during drying. Depending on the type of asphalt being mixed and the respective rate of addition of the recyclable material, the temperature level is usually up to 450°C. Drying takes place in a rotary kiln, also known as a drying drum. Heat is fed to the rotary kiln, which has previously been generated by a separate heating unit. Heat generation is usually based on the combustion of fossil fuels, such as natural gas, liquefied petroleum gas, heating oil, and / or coal dust. The combustion of fossil fuels produces carbon dioxide, which is problematic from a climate perspective.

[0004] It is the object of the present invention to make the drying of material for an asphalt mixing plant ecologically advantageous and, in particular, climate-friendly.

[0005] This object is achieved according to the invention by a device having the features specified in claim 1 and by an asphalt mixing plant having the features specified in claim 11.

[0006] According to the invention, it was recognized that material can be dried in an ecologically advantageous manner if heat, which is used in a rotary kiln to dry the material, is generated by means of a hydrogen gas burner. The hydrogen gas burner is a burner in which hydrogen gas is burned to generate heat. The device can also comprise a plurality of burners, which are in particular identical. The burners can also be designed differently, with at least one burner, in particular a plurality of burners and in particular all burners being designed as hydrogen gas burners. Hydrogen gas therefore serves as fuel. According to the invention, the heat is generated at least partially and in particular exclusively by the combustion of hydrogen gas. The combustion of hydrogen gas is carbon dioxide-free, i.e. no carbon dioxide is generated. The combustion of hydrogen gas is climate-friendly. Exhaust gases and emissions are reduced.It is particularly advantageous if the hydrogen gas has been produced from renewable energies, i.e. it is so-called green hydrogen.

[0007] In the rotary kiln, materials that can be used for an asphalt mixture are dried, such as old asphalt material, which is also referred to as recycled material or RC material, and / or mineral rock, in particular white mineral. The rotary kiln is designed to be driven in rotation about a rotation axis and is in particular cylindrical in shape. The rotary kiln has a material inlet, at which the material to be dried is fed to the rotary kiln, and a material outlet, at which the dried material is discharged from the rotary kiln. The material inlet and the material outlet are arranged at a distance from one another with respect to the rotation axis. In particular, the material inlet and the material outlet are each arranged in the region of the end faces of the rotary kiln and are in particular designed opposite one another on the end face of the rotary kiln.

[0008] The material inlet can have a material chute, a conveyor belt, a feed belt or other conveying techniques.

[0009] The material outlet may include a material chute and / or a circular elevator or other conveying technology.

[0010] To facilitate material transport in the rotary kiln, the rotary kiln is arranged with its axis of rotation inclined relative to a horizontal direction, in particular toward the material outlet. The angle of inclination is in particular at most 8°, in particular at most 5°, in particular at most 4°, in particular at most 3°, and in particular at least 1°. The residence time of the material within the rotary kiln is in particular at least one minute and in particular at most 10 minutes.

[0011] The burner, which combusts the hydrogen gas to generate heat, is part of a heating unit coupled to the rotary kiln for heat transfer. "Coupled" in the context of the invention means that the burner and rotary kiln are technically coupled. A burner flame generated by the burner can burn directly in the rotary kiln. In this application example, the burner and rotary kiln are also physically coupled. The burner is located directly next to the rotary kiln.

[0012] The burner flame can also burn in a hot gas generator, which transfers the heat to the rotary kiln via an air stream. The heat generated by the burner is fed from the heating unit into the rotary kiln. The heat supply to the rotary kiln includes the generation of heat by the burner flame directly in the rotary kiln.

[0013] The burner has a burner housing with a longitudinal axis and an air duct. In the context of this invention, air duct describes the supply of combustion air. In particular, this can be provided by a fan arranged in the burner housing, a fan connected via an air duct, or another air supply. In particular, a flange is arranged on the burner housing, in particular on the front side, with which a silencer can be connected to the burner housing. Air, in particular ambient air, is supplied to the burner housing by means of the air duct. In particular, the air duct is connected to the burner housing axially with respect to the longitudinal axis. The supply of air to the burner housing is thereby simplified.

[0014] A hydrogen gas line is connected to the burner, in particular to the burner housing, in order to supply hydrogen gas to the burner. A hydrogen gas nozzle is connected to the hydrogen gas line in order to release the hydrogen gas in a targeted manner in the burner housing. For the purposes of this invention, a hydrogen gas nozzle can be designed as an annular nozzle, annular gap, gas lance, needle nozzle or as an outlet in any other form. This promotes the generation of an air-hydrogen gas mixture and / or the generation of a burner flame. The hydrogen gas nozzle is arranged in particular within the burner housing and is designed in particular as an annular nozzle with radial openings. There can also be several hydrogen gas nozzles which are identical or different from one another. The hydrogen gas nozzles can be arranged at different positions relative to the longitudinal axis, in particular in the radial, tangential and / or axial direction.

[0015] The burner additionally has a swirling element, which serves to swirl the combustion air, to mix fuel and combustion air, as a flame holder, as a mount for fuel nozzles, for pilot burners or other burner components and / or for similar purposes. In particular, in the variant designed, a swirling element is introduced to swirl the air in the burner housing relative to the longitudinal axis, in particular tangentially, radially and / or axially. The mixing of the air with the hydrogen gas is thereby improved, in particular the homogeneity of the air-hydrogen gas mixture. In particular, the hydrogen gas nozzle is arranged adjacent to the swirling element and opens out in particular immediately upstream of the swirling element. The swirling element serves to define the shape of the burner flame generated by the burner.In particular, the flame, especially if it is located inside the rotary kiln, should not exceed a maximum length along the rotary kiln's axis of rotation to prevent direct contact of the flame with the material in the rotary kiln. Furthermore, the maximum diameter of the flame should not exceed an upper limit; in other words, the flame must not be too wide, as this would expose the rotary kiln to excessive heat stress. This protects the drying drum.

[0016] The burner housing has a burner head that serves to generate the burner flame. For the purposes of this invention, the burner head is understood as an opening located on the front side of the burner housing, where the flame develops. The burner head can, in particular, be designed to widen conically at least in sections along its longitudinal axis.

[0017] In particular, a hydrogen reservoir can be provided in which hydrogen, in particular hydrogen gas, is stored. The hydrogen reservoir is connected to the burner housing in particular by means of the hydrogen gas line. In particular, a gas safety and / or gas control line is provided along the hydrogen gas line in order to ensure a reliable and safe supply of the hydrogen gas from the hydrogen reservoir to the burner housing. The gas safety and / or gas control line comprises, in particular along the gas flow direction, a shut-off valve, a gas filter, a gas pressure regulator, in particular with impulse lines, a pressure relief valve, in particular at least one pressure switch, in particular at least one safety shut-off valve, in particular further pressure switches, a gas control flap and / or an additional shut-off flap, and in particular at least one pressure gauge.The hydrogen reservoir and / or the hydrogen gas line, and in particular the hydrogen gas nozzle, are each made of a material that is suitable for storing, conveying, and / or dispensing hydrogen gas and is specifically approved for this purpose. The components of the gas control system are specifically approved for use with hydrogen.

[0018] A swirling element according to claim 2 ensures efficient air swirling. A flow guide element is arranged in the burner housing, in particular concentrically to the longitudinal axis. The flow guide element is arranged stationary, i.e., immobile, in the burner housing. In particular, the flow guide element has no moving parts. The flow guide element is low-maintenance and, in particular, maintenance-free. The flow guide element is robust and reliable.

[0019] In addition to or as an alternative to the stationary flow guide element, it is possible to supply the air line tangentially and / or radially relative to the longitudinal axis of the burner housing, i.e., to connect the air line tangentially and / or radially to the burner housing. In this case, the swirl element is formed by a tangential air supply.

[0020] A baffle plate according to claim 3 enables advantageous swirling of the air and advantageous generation of the air-hydrogen gas mixture. A plurality of blades arranged in a circle with respect to the longitudinal axis and oriented at an angle enable targeted deflection of the axial air flow radially and / or tangentially outwards towards the inner wall of the burner housing. In particular, the baffle plate has a section at which the hydrogen gas nozzle opens and a further area to which the air is supplied. In particular, the area for supplying the hydrogen gas is annular and oriented concentrically to the longitudinal axis. The area for supplying the air at the baffle plate is arranged centrally, i.e., concentrically. In particular, the two areas for supplying the hydrogen gas and air are designed to be separate from one another on the baffle plate.At least one additional area for the supply of a secondary fuel can be provided on the baffle plate. This at least one additional area can be separate from the other areas or connected to them. This additional area can be arranged centrally or eccentrically on the baffle plate.

[0021] The swirling element, particularly in the form of a baffle plate, makes it easier to adjust the shape of the burner flame regardless of the fuel used, and in particular regardless of whether secondary fuel is used in addition to hydrogen gas. In particular, it is possible to adjust the shape of the burner flame depending on the fuel used, in particular the fuels used, so that the burner flame is suitable for drying the material in the rotary kiln, i.e., provides sufficient heat, and, moreover, damage to the rotary kiln and / or the material to be heated is excluded. The shape of the burner flame is influenced in particular by the number, design, and arrangement of the nozzles for supplying the hydrogen gas and the at least one secondary fuel. The flame shape also depends in particular on the air curve.

[0022] The arrangement and / or size of the various areas of the baffle plate depends primarily on the fuels to be burned. Additionally or alternatively, it is possible to modify the geometry of the blades, change the arrangement of the blades within the baffle plate, and / or provide additional guide elements, such as cones and / or facing plates.

[0023] A cooling cone according to claim 4 enables air staging within the burner housing. With air staging, several combustion zones are created around the burner flame, which have different oxygen concentrations and increase in particular from the inside out, i.e. in a radial direction. This increases the combustion area and thus also the residence time of the components in the burner flame. By means of air staging, the formation of thermal nitrogen oxides (NO x) is reduced and in particular complete combustion of the fuel, in particular hydrogen gas, can be achieved. The cooling cone has a widening conical section. The cooling cone is arranged in the burner housing at the transition to the burner head. An annular gap is created between the outside of the cooling cone and the inside of the burner housing, in particular with a gap width that remains constant along the longitudinal axis. In addition, the cooling cone ensures an air flow through said annular gap, whereby the axially flowing air is kept away from the burner flame, i.e. is guided around the burner flame and supplied to the flame in the area of the burner head. This secondary air, which has been guided around the burner flame, cools the burner head, in particular in the area of the cooling cone. In particular, the flame temperature can also be reduced as a result in order to reduce the formation of nitrogen oxides.

[0024] Additionally or alternatively, air staging can also be ensured by means of an additional air connection, for example, a secondary air connection. Secondary air can also be ambient air. In particular, a secondary air line can be a return line to recirculate emission-laden air from the rotary kiln for post-combustion and co-combustion.

[0025] Additionally or alternatively, measures for nitrogen oxide reduction are possible, in particular local combustion at different air / fuel ratios (λ), which defines the mass ratio of air to fuel in the combustion chamber. In particular, combustion at λ >> 1 or at λ << 1 is possible. Additionally or alternatively, it is conceivable to add urea in a targeted manner in order to reduce nitrogen oxide formation. It is advantageous if the flame temperature is less than 1400°C, in particular less than 1350°C, in particular less than 1300°C, in particular less than 1250°C and in particular less than 1200°C. It has been found that the formation of thermal NO x is reduced if the flame temperature does not exceed a specified maximum value.

[0026] A secondary fuel line according to claim 5 increases the application variability of the burner. Several secondary fuel lines can also be connected to the burner, in particular to supply different types of secondary fuels. Examples of secondary fuels that can serve as secondary fuels include natural gas, liquefied petroleum gas, heating oil, wood dust, coal dust, and / or synthetic fuels. Such synthetic fuels are typically produced from biomass by thermochemical conversion and are referred to as biomass to liquid (BtL). The secondary fuels can be fed to the burner in addition to the hydrogen gas, especially when the hydrogen gas supply is limited and / or interrupted. It is also conceivable in principle to control the secondary fuel supply such that the burner is operated exclusively with secondary fuel, i.e., without hydrogen.However, it is essential that at least the hydrogen gas line and the hydrogen gas nozzle are provided.

[0027] A secondary fuel nozzle is connected to the secondary fuel line to discharge the secondary fuel. Multiple secondary fuel nozzles can also be connected to the secondary fuel line. The secondary fuel nozzle is located inside the burner housing. The secondary fuel nozzle opens, in particular, at the baffle plate, particularly centrally.

[0028] The axial arrangement of the air according to claim 6 enables a simple and robust design. A fan for generating the air flow in the air line can, in particular, be designed as an axial fan and arranged integrated into the air line. It is also possible to design the fan as a radial fan. A silencer is, in particular, connected to the air line. The fan can also be arranged outside the burner housing, in particular upstream of the air line.

[0029] An exhaust line according to claim 7 enables the co-combustion of exhaust gases, in particular in the burner. For the purposes of this invention, both exhaust gases from combustion processes and, in particular, exhaust gases from asphalt production, in particular through extraction during the mixing process and the further handling of the asphalt, are referred to. These exhaust gases are fed to the burner, in particular as emission-laden air. This allows emissions to be further reduced, in particular odor emissions, carbon monoxide (CO), carbon dioxide (CO2), and, in particular, hydrocarbons (C ges ) in total. The exhaust gas line can additionally or alternatively supply exhaust gases to the heating unit as a whole and / or into the rotary kiln.

[0030] A heating unit with a hot gas generator according to claim 8 enables indirect heating of the rotary kiln and thus indirect drying of the material in the rotary kiln. The hot gas generator is connected to the rotary kiln, in particular via a hot gas line. The hydrogen burner serves to generate process heat in the hot gas generator.

[0031] Alternatively, the burner can be directly connected to the rotary kiln and, in particular, directly integrated into the rotary kiln. In particular, the burner is attached to the front of the rotary kiln, particularly in the area of the material outlet. The burner head is arranged, in particular, within the rotary kiln. Such a rotary kiln operates in countercurrent. This means that the material conveying direction and the direction of heat supply are opposite to one another. In this case, the hydrogen burner burns directly within the rotary kiln. The hydrogen burner operates in a dusty environment.

[0032] A rotary kiln, which has, in particular, closed fire protection fittings arranged on an inner wall of the rotary kiln and in particular fastened thereto, ensures that the material in the rotary kiln is protected in the area of the burner flame. Direct material contact with the burner flame is avoided. Fire protection fittings, which are in particular designed to be closed so that the material is arranged all around in these closed fire protection fittings, are arranged on an inner side of the rotary kiln and fastened thereto. This ensures that the material remains in these closed fittings. Undesired contact of the fittings with the burner flame is avoided. The heat emitted by the burner flame is dissipated into the interior of the material via the fire protection fittings. The fire protection fittings are made in particular of heat-resistant and / or wear-resistant material.In particular, steel alloyed in such a way that it has high temperature resistance is used for this purpose, in particular heat-resistant steel, in particular heat-resistant pressure vessel steel, in particular a pressure vessel steel with the material number 1.5415, which is also known by the abbreviation 16Mo3. Such a material can be used in continuous operation up to a wall temperature of approximately 530°C.

[0033] The fire protection fittings are arranged particularly in the area of a burnout zone of the rotary kiln.

[0034] The fire protection inserts form closed pockets on the inner surface of the rotary kiln. The material is conveyed and dried in these closed pockets until it is discharged at the material outlet along the material conveying direction of the rotary kiln.

[0035] A rotary kiln, which in particular has open throwing plates that are arranged on an inner wall of the rotary kiln and in particular are fastened thereto in order to create a, in particular closed, material curtain in the rotary kiln, ensures the creation of a material curtain in the rotary kiln. Because the rotary kiln is arranged in particular at an incline with respect to the horizontal direction, the throwing plates ensure material conveyance along the material conveying direction. The material curtain is formed in particular in a heat transfer region that is arranged upstream of the burnout zone in the rotary kiln with respect to the material conveying direction. In the heat transfer region, the rotary kiln has throwing plates that are arranged on the inner wall of the rotary kiln and in particular are fastened thereto. The throwing plates are open, i.e. they are open internals.

[0036] The throwing plates are, in particular, edged multiple times. Material picked up in the lower area during rotation of the rotary kiln rains down via the rotary kiln's circulation system. A curtain is formed across the cross-sectional area of the rotary kiln, and thus, in particular, a closed curtain. The throwing plates are made of a heat-resistant and / or wear-resistant material. In particular, the same material is used for the throwing plates as for the fire protection fittings.

[0037] The internals in the rotary kiln, particularly the throwing plates in the heat transfer zone, are designed such that the material curtain ensures heat transfer such that the volume flow of the exhaust gas from the rotary kiln meets the conditions for subsequent filter dedusting, i.e., in particular, that the exhaust gas has a temperature above its dew point and below the flash point of the filter pockets. In particular, the temperature of the exhaust gas upon leaving the rotary kiln is up to 160°C, particularly between 90°C and 110°C.

[0038] A rotary kiln according to claim 10 enables reliable material conveyance in the rotary kiln, in particular starting at the material inlet. For this purpose, at least one and in particular several conveying elements are provided in the rotary kiln, which are arranged on an inner wall of the rotary kiln and in particular are fastened thereto. The conveying elements are designed in particular as inlet screw segments that extend along a helical line in the rotary kiln. In particular, eleven inlet screw segments are arranged.

[0039] An asphalt mixing plant according to claim 11 essentially has the advantages of the device according to claim 1, to which reference is hereby made. The asphalt mixing plant can have a filter dedusting system and / or a condensate separator. In the filter dedusting system, dust particles are filtered out of the exhaust gas from the rotary kiln.

[0040] In the condensate separator, water contained in the exhaust stream can condense. This releases additional energy in the form of heat. This use of calorific value in the condensate separation system enables the separation of undesirable components, particularly acids, from the exhaust gas. The exhaust gas is additionally cleaned by the condensate separator. The condensate separator is located downstream of the filter dust collection system.

[0041] The asphalt mixing plant also has, in particular, a blower and / or a chimney, which are arranged downstream of the filter dust removal and / or the condensate separator.

[0042] The asphalt mixing plant can additionally have at least one mixing unit in which various materials required for an asphalt mixture are mixed together. These materials can, for example, originate from the rotary kiln. It is also conceivable for materials to be fed directly into a mixing unit, particularly via a dosing device.

[0043] A method for drying material for the asphalt mixing plant comprises the process steps of feeding the material into a rotary kiln that can be rotated about the axis of rotation, generating heat with a burner of a heating unit by burning hydrogen gas, feeding the heat into the rotary kiln and drying the material.

[0044] A method in which exhaust gases are fed to the heating unit, in particular to the burner, and / or to the rotary kiln by means of an exhaust gas line enables particularly efficient co-combustion of exhaust gases, so that the overall emissions are reduced.

[0045] A method in which heat is supplied by a burner flame within the rotary kiln, such that the burner flame is located, in particular, in a dust-laden environment, wherein, in particular, the burner flame in the rotary kiln has a length oriented along the axis of rotation that is less than or equal to a length oriented along the axis of rotation of a burnout zone of the rotary kiln, enables heat to be supplied directly to the rotary kiln. The burner flame is located, at least partially and in particular entirely, within the rotary kiln, i.e., in a dust-laden environment.

[0046] A method in which the burner flame has a diameter oriented perpendicular to the rotational axis that is smaller than the inner diameter of the burnout zone of the rotary kiln, which is reduced by fire protection fittings, ensures that the burner flame is reliably positioned within the burnout zone of the rotary kiln and, in particular, that fire protection fittings of the rotary kiln are arranged at a distance, particularly radially, from the burner flame. Direct contact of the burner flame with the fire protection fittings is prevented.

[0047] Both the features specified in the claims and the features specified in the following embodiment of the device according to the invention are suitable, either individually or in combination with one another, for further developing the subject matter of the invention. The respective combinations of features do not represent any limitation with regard to further developments of the subject matter of the invention, but are essentially merely exemplary in nature.

[0048] Additional features, advantageous embodiments, and details of the invention will become apparent from the following description of an embodiment with reference to the drawings. Fig. 1 a schematic sketch of an asphalt mixing plant with a device according to the invention, Fig. 2 a schematic sectional view of a rotary kiln with burner according to Fig. 1, Fig. 3 an enlarged sectional view according to section line III-III in Fig. 2, Fig. 4 an enlarged sectional view according to section line IV-IV in Fig. 2, Fig. 5 an enlarged detailed view of detail V in Fig. 2, Fig. 6 a perspective view of the baffle plate in Fig. 5, and Fig. 7 a rear view of the baffle plate according to Fig. 5.

[0049] One in Fig. The asphalt mixing plant shown as a whole at 1 is used to produce asphalt. The asphalt mixing plant 1 comprises a first device 2 and a second device 3, each of which is connected to a filter dedusting system 5 via an emission line 4.

[0050] The asphalt mixing plant 1 may also have only one device 2, 3 or more than two devices 2, 3. It is conceivable that the one or more devices 2, 3 are connected to the filter dedusting system 5 via a common emission line 4. In particular, the filter dedusting system 5 is a central filter dedusting system in the asphalt mixing plant, to which several, and in particular all, devices 2, 3 of the asphalt mixing plant 1 are connected. It is also conceivable that each device 2, 3 is assigned to and connected to a separate filter dedusting system 5.

[0051] A condensate separator 6 is optionally connected to the filter dust collector 5 and is connected to a chimney 8 via a fan 7. The condensate separator 6 can, as shown in Fig. 1, are arranged behind the filter dedusting system 5 and additionally or alternatively also upstream of the filter dedusting system 5. In particular, in addition to the condensate separator, a recuperation unit is provided which serves to recover process heat, in particular process heat that arises in the condensate separator 6. It has been found that the condensate separator 6 can be advantageously used in the asphalt mixing plant 1 if the exhaust air from the devices 2, 3 is comparatively clean, i.e., has a reduced emission load and, in particular, is less polluted with emissions than the exhaust air from a burner that burns fossil fuels.

[0052] It is also possible for the asphalt mixing plant 1 not to have a filter dedusting system 5. In this case, the devices 2, 3 are directly connected to the condensate separator 6. It is also conceivable that several condensate separators 6 are provided, in particular one condensate separator 6 per device 2, 3.

[0053] The first device 2 comprises a rotary kiln 9 in which material is dried. The rotary kiln 9 has a material inlet 10 and a material outlet 11. According to the illustrated embodiment, the material inlet 10 and the material outlet 11 are each arranged at the end, i.e., opposite each other, of the rotary kiln 9.

[0054] A heating unit having a burner 12 is coupled to the rotary kiln 9. The burner 12 is designed to combust hydrogen gas and generate a burner flame 13, which is arranged at least partially in the rotary kiln 9. The burner 12 is a hydrogen burner. A hydrogen gas line 14 is connected to the burner 12 and is connected in particular to a hydrogen reservoir 15. The hydrogen reservoir 15 is in particular a storage container, in particular a storage tank, in which hydrogen, in particular in gaseous form, is stored. The hydrogen reservoir 15 can also be designed as a connection to a hydrogen supply network. The connection to the gas control line in the hydrogen gas line 14 is made at a hydrogen gas distribution chamber 30 by means of a compensator 62. The compensator 62 is a flexible compensating element.The compensator 62 serves to compensate for movements of the hydrogen line 14, particularly due to thermal length changes, vibrations, wall penetrations, and / or settlement phenomena. The compensator 62 is arranged at a flange connection 63 between the hydrogen distribution chamber 30 and the hydrogen gas line 14.

[0055] An air line 16 is connected to the burner 12 to supply air, in particular ambient air.

[0056] A material conveying direction 22 through the rotary kiln 9 is directed from the material inlet 10 to the material outlet 11 and according to Fig. 1 from right to left. A gas conveying direction 23 through the rotary kiln 9 is directed from the burner 12 to the emission line 4, i.e. according to Fig. 1 from left to right. The material conveying direction 22 and the gas conveying direction 23 are oriented opposite to each other. The rotary kiln 9 is operated in a countercurrent process. The rotary kiln 9 can also be operated in a cocurrent process.

[0057] Furthermore, a first secondary fuel line 17 is connected to the burner to supply a first secondary fuel. Fossil fuels, such as natural gas, liquefied petroleum gas, heating oil, coal, particularly coal dust, synthetic fuels (BtL), and / or wood dust, serve as secondary fuels. In the illustrated embodiment, natural gas is used as the first secondary fuel. The first secondary fuel line 17 is fed from a secondary fuel reservoir (not shown). The secondary fuel reservoir can be designed as a storage container and / or a supply network, similar to the hydrogen reservoir 15.

[0058] The connection to the first secondary fuel line 17 and the gas control line there is made at a secondary fuel distribution chamber 32 by means of a compensator 66. The compensator 66 is essentially identical to the compensator 62 and is arranged at a corresponding location between the first secondary fuel line 17 and the secondary fuel distribution chamber 32.

[0059] It is understood that when using a different first secondary fuel, for example a liquid secondary fuel such as liquefied petroleum gas and / or oil, the burner may have a different geometry, this particularly applying to the burner head, the baffle plate, the combustion chamber, the arrangement, number and attachment of the nozzles used and the peripherals such as an oil control line and / or a liquefied petroleum gas control line.

[0060] The first device 2 further comprises an exhaust line 18, which is connected to the heating unit, in particular the burner 12, and / or to the rotary kiln 9. By means of the exhaust line 18, exhaust gases and / or emissions can be fed to the heating unit and / or the rotary kiln 9. The exhaust line 18 basically serves as a supply line for secondary air, which can in particular be exhaust air from other emission sources, such as in particular the extraction of a bucket conveyor and / or a loading area. The secondary air is in particular emission-laden air. The exhaust line 18 can, for example, be connected to the emission line 4 of the first device 2 and / or to the emission line 4 of the second device 3 in order to recirculate exhaust gases. Additionally or alternatively, other exhaust gas sources of the asphalt mixing plant 1 can be connected to the exhaust line 18.A separate fan 48 is arranged in the exhaust line 18, which can supply additional combustion air. One or more dampers 49 can be arranged along the exhaust line 18 to specifically control the air flow and, in particular, to specifically adjust the amount of air supplied. Additionally or alternatively, air flow control can also be achieved with the fan 48 and, in particular, by means of a frequency converter connected to it.

[0061] According to the illustrated embodiment, the exhaust line 18 is branched, with a first branch opening directly into the rotary kiln 9, in particular adjacent to the burner head 41. Another part of the exhaust line 18 opens directly into the burner housing 27, in particular in the region of an annular gap 50 and / or in the region of the burner head 41.

[0062] The rotary kiln 9 is designed to be driven in rotation about a rotational axis 19. The drives required for this, in particular rotary drives, are known per se and are not shown in the figures for reasons of clarity. Along the rotational axis 19, the rotary kiln 9 has a burnout zone 20, which extends along the rotational axis 19 in the region of the burner flame 13.

[0063] The rotary kiln 9 further comprises a heat transfer region 21 in which heat is transferred to the material by convection.

[0064] The second device 3 is constructed essentially identically to the first device 2, to which reference is hereby made. One difference is that the heating unit of the second device 3 comprises a hot gas generator 24 in addition to the burner 12. The hot gas generator 24 is connected to the rotary kiln 9 by means of a hot gas line 25. The hot gas generator 24 is arranged between the burner 12 and the rotary kiln 9. In the second device 3, the burner 12 is designed separately from the rotary kiln 9. In particular, the burner 12 is arranged completely outside the rotary kiln 9. Accordingly, the burner flame 13 is arranged in the hot gas generator 24. No burner flame is arranged in the rotary kiln 9 of the second device 3. In the second device 3, recirculation fans and / or exhaust air fans (not shown in detail) can be used to guide the air, in particular in the rotary kiln 9 and / or in the hot gas generator 24.The fans are arranged, in particular, outside the rotary kiln 9 and / or outside the hot gas generator 24, in particular along connecting lines. Accordingly, a burnout zone 20 is not required in this rotary kiln 9. The rotary kiln 9 of the second device 3 essentially comprises only a heat transfer area 21.

[0065] In the illustrated embodiment, each device 2, 3 has its own separate hydrogen reservoir 15. It is also conceivable that a common, centrally located hydrogen reservoir 15 is available in an asphalt mixing plant 1, which is in fluid communication with several and at least with all burners 12 of the asphalt mixing plant 1.

[0066] The following are based on Fig. 2 The structure and function of the first device 2, in particular the burner 12, are explained in more detail.

[0067] The burner 12 has a burner housing 27 having a longitudinal axis 26. The burner housing 27 has an intake chamber 28 at an end facing away from the rotary kiln 9, through which air, in particular ambient air, is sucked into the burner housing 27. For this purpose, the air line 16 and / or a silencer can be connected to the intake chamber 28. An air blower 29 is arranged along the burner housing 27, which, according to the exemplary embodiment shown, is designed as an axial blower. It is understood that the air blower 29 can also be designed as a different type of blower, in particular as a radial blower.

[0068] The burner 12 has, in particular, a flame sensor 64, which serves to monitor the burner flame 13. In particular, several flame sensors 64 can be implemented on the burner 12 and arranged spaced apart from one another, in particular in the burner housing 27, in particular along the longitudinal axis 26. Furthermore, an ignition burner 65 is provided in the burner housing 27, which serves to ignite the burner flame 13.

[0069] The hydrogen line 14 is connected to the burner housing 27 via a hydrogen gas distribution chamber 30 arranged annularly around the burner housing 27. At least one hydrogen gas nozzle 31 is connected to the hydrogen gas distribution chamber 30 in order to supply the hydrogen gas in a targeted manner into the burner housing 27. It is conceivable that no hydrogen gas distribution chamber 30 is provided. In this case, the hydrogen line 14 is directly connected to the hydrogen nozzle 31.

[0070] The hydrogen gas nozzle 31 is designed, in particular, as an annular nozzle. It is also conceivable for the hydrogen gas nozzle 31 to have a different geometry and, in particular, to be designed as a gas lance. It is also conceivable for a plurality of, in particular differently designed, hydrogen gas nozzles 31 to be provided, which are arranged at different positions, in particular along the longitudinal axis 26 and / or at different positions in the circumferential direction and / or at different radial distances relative to the longitudinal axis 26 in the burner housing 27.

[0071] A secondary fuel distribution chamber 32 is connected to the first secondary fuel line 17, the function of which corresponds to the hydrogen gas distribution chamber 30, to which reference is hereby made. According to the exemplary embodiment shown, a plurality of secondary fuel nozzles 33 are arranged in the burner housing 27 and connected to the secondary fuel distribution chamber 32. The secondary fuel nozzles 33 are each designed as gas lances and are arranged adjacent to the hydrogen nozzle 31 in the burner housing 27. The first secondary fuel nozzles 33 are arranged in the burner housing at a distance from each other in the radial direction relative to the longitudinal axis 26.

[0072] As in Fig. 2, a second secondary fuel nozzle 34 is arranged in the burner housing 27, which serves to supply liquid fuels. The second secondary fuel nozzle 34 is arranged centrally, i.e., centrically relative to the longitudinal axis 26, in the burner housing 27. A second secondary fuel line is connected to the second secondary fuel nozzle 34, which for illustration purposes is Fig. 2 is not shown. The second secondary fuel nozzle 34 serves in particular for supplying oil, in particular light oil and / or heavy oil. The second secondary fuel nozzle 34 is designed, for example, as a compressed air or return nozzle. The second secondary fuel nozzle 34 can also be designed as an annular nozzle with multiple liquid gas nozzles.

[0073] The burner 12 is a combination burner, in particular a three-fuel burner, which can combust hydrogen gas, a first, in particular gaseous, secondary fuel, in particular natural gas, and a second, in particular liquid, secondary fuel, in particular light oil. The various fuels can be supplied to the burner 12 independently by means of its suitable control system, in particular such that either only one of the three fuels, in particular hydrogen, two of the three fuels, or all three fuels are supplied to the burner 12 and combusted there.

[0074] A swirl element 35 is arranged in the burner housing 27 in the area of the nozzles 31, 33, and 34. The swirl element 35 serves to tangentially swirl the air. The swirl element 35 is designed, in particular, as a baffle plate, which in particular has a guide vane. Depending on the fuel combination used, the baffle plate 35 can be designed differently in terms of diameter, shape, and structural details.

[0075] In the illustrated embodiment, the nozzles 31, 33, 34 are each arranged upstream of the swirling element 35. It is possible for individual nozzles 31, 33, 34, several of the nozzles, or all of the nozzles to be arranged downstream of the swirling element 35 in the burner housing 27. The geometry of the burner flame 13 also depends on the number and / or position of the nozzles 31, 33, and 34.

[0076] The use of the various nozzles 31, 33, and 34 enables separate addition of the various fuels. In particular, time-controlled addition of the various fuels and, in particular, spatially separate addition of the fuels is possible. The amount of fuel added and / or the time of addition are controlled by a burner control system (not shown in detail). The burner control system can be controlled by temperature monitoring using temperature sensors (not shown in detail) and / or as a function of a signal generated by the flame sensor 64.

[0077] In particular, it is possible to apply a stepped addition of the hydrogen gas, for example by designing the hydrogen gas nozzles as gas lances of different lengths and / or with a radially arranged gas outlet.

[0078] The swirling element 35 is arranged in a cooling cone 36. According to the exemplary embodiment shown, the cooling cone 36 has a cylindrical section whose outer diameter is at least 80% of the inner diameter of the burner housing 27 at this point. In particular, the outer diameter of the cooling cone 36 is at least 85%, in particular at least 90%, in particular at least 95%, and in particular at most 99% of the inner diameter of the burner housing 27 at this point. The cooling cone 36 is arranged in particular in a region of the burner housing 27 in which the burner housing widens conically. The burner housing 27 has an expanding section 39 which merges into a closing section 40. The closing section 40 and the expanding section 39 form a burner head 41. A circumferential annular gap 50 is formed between an outer wall of the cooling cone 36 and an inner wall of the burner head 41.The air flowing through this annular gap is referred to as secondary air. The secondary air flows past the cooling cone 36. The air flowing through the cooling cone 36 is referred to as primary air. Because at least a portion of the air is directed past the cooling cone 36 as secondary air, air staging is possible.

[0079] In the illustrated embodiment, the burner head 41 improves the mixing of the fuels, particularly hydrogen with air. The burner flame 13 forms downstream of the burner head 41, with the shape of the burner flame 13 being influenced by the geometry of the burner head 41. This means that by appropriately selecting the burner head geometry, the shape of the burner flame 13 can be specifically adjusted. In particular, the diameter D F the burner flame 13 is greater, the larger the diameter at the outlet of the burner head 41 is.

[0080] The burner 12 is attached to an end wall 42 of the rotary kiln 9. The end wall 42 is referred to as the outlet end wall because the material outlet 11 is located in this area. The burner 12, in particular the burner housing 27, is attached to the end wall 42 by means of fastening elements not shown in detail.

[0081] As in Fig. As indicated in Figure 2, the end wall 42 is arranged on the rotary kiln 9, particularly in the axial direction and / or in the radial direction relative to the rotation axis 19, overlapping it. In particular, the rotary kiln 9 is not hermetically sealed by the end wall 22. A circumferential gap 46 remains between the end wall 42 and the rotary kiln 9. The circumferential gap 46 allows for an additional supply of air, particularly ambient air.

[0082] The burner 12 is arranged on the rotary kiln 9 in particular such that the longitudinal axis 26 of the burner housing 27 and the rotational axis 19 of the rotary kiln 9 coincide, i.e., are identical. The burner 12 is arranged concentrically to the rotary kiln 9.

[0083] The burner 12 is attached directly to the rotary kiln 9 and is at least partially integrated therein. In particular, the burner head 41 and the burner flame 13 generated by the burner 12 are arranged entirely within the rotary kiln 9.

[0084] The burner 12 has a burner frame 47, with which the burner 12 is placed on a base. According to the illustrated embodiment, the burner frame 47 is static, i.e., immobile, in particular fixed. It is also conceivable for the burner frame to have rollers on its underside, which can roll, in particular, on suitable rails. In particular, it is conceivable for an axial displacement of the burner 12 along the rails to occur by means of an axial drive, in particular by means of a pneumatic drive.

[0085] Along the longitudinal axis 26 or the rotational axis 19, the burner flame 13 has a length L F and a diameter D oriented perpendicular to it F on.

[0086] The rotary kiln 9 has an inner diameter D iIn the burnout zone 20, fire protection fittings 43 are provided, which are attached to the inner wall of the rotary kiln 9. As a result of the fire protection fittings 43, a reduced inner diameter D results in the burnout zone 20. red In the axial direction, the fire protection fittings 43 extend along a length L A , which corresponds to the length of the burnout zone 20. It is essential that the length L A the burnout zone 20 is greater than the length L F the burner flame 13, and that the burner 12 is arranged on the rotary kiln 9 such that the burner flame 13 is arranged entirely within the burnout zone 20, in particular in the axial direction relative to the rotation axis 19. Furthermore, it is essential that the diameter D F the burner flame 13 is smaller than the reduced diameter D red Direct flame contact with the fire protection fittings 43 is avoided.

[0087] In the heat transfer area 21, throwing plates 44 are arranged and fastened in particular to the inside of the rotary kiln 9. The throwing plates 44 are open and serve to create a material curtain 45. It is particularly advantageous if the material curtain is as dense as possible. It is possible to quantify the density of the material curtain 45 indirectly, in particular by measuring the exhaust gas temperature. The lower the exhaust gas temperature, the greater the previous heat transfer to the material. This means that the material curtain 45 is denser the lower the exhaust gas temperature, and vice versa. The exhaust gas temperature results from the burner output, the pre-metering output, i.e. the mass flow of the material fed into the rotary kiln 9, and the material temperature. The material temperature serves in particular as an input variable for controlling the burner output.It has been found that it is advantageous if the exhaust gas temperature in the embodiment shown is at least 100°C. It is understood that depending on the material used, the burner 12 used, or the fuels used, the exhaust gas temperature for monitoring the material curtain 45 can assume other values.

[0088] The following is based on Fig. 3 the geometry of the throwing plates 44 is explained in more detail. It is possible that different geometries of throwing plates are used. According to the illustration shown, two different throwing plate geometries are arranged alternately and spaced apart from one another along the circumferential direction. The individual throwing plates 44 are fastened to the inside of the rotary kiln 9 by means of a holding element, in particular a holding angle. The throwing plates 44 are so-called open internals and are in particular designed like scoops. The throwing plates 44 are folded several times, i.e. have at least two edges 51. During operation of the rotary kiln 9, the throwing plates 44 pick up the material to be dried and release it again in an upper area as the rotary kiln 9 rotates. The throwing plates 44 are designed in such a way that the densest, most continuous and homogeneous material curtain 45 is formed.The material veil 45 has a particularly large surface area, which improves heat transfer by convection.

[0089] The specific geometry of the throwing plates 44, and in particular their arrangement on the inside of the rotary kiln 9, can vary for different materials, different material moisture contents, and / or drying capacities in order to create the densest possible material curtain 45. For example, when drying recycled asphalt, rake-like fixtures, radially aligned half-shells, or other geometries can be advantageous for creating the material curtain. The reason for this is that the discharge characteristics from the throwing plates 44 can vary depending on the material used, its moisture content, and / or the drying capacity of the rotary kiln 9.

[0090] The following are based on Fig. 4 Geometry and function of the fire protection installations 43 are explained in more detail. The fire protection installations 43 are closed installations, thus forming Fig. 4, a substantially C-shaped frame, which is arranged with its open side on the rotary kiln 9 and is thereby closed. Each fire protection installation 43 and the corresponding section of the rotary kiln 9 form a closed chamber 67, which can only be opened in the axial direction, i.e. perpendicular to the plane of the drawing of the Fig. 4 is open.

[0091] The fire protection fittings 43 are each held by means of a retaining clip 52.

[0092] The material arranged in chamber 67 is protected. Direct contact with the burner flame 13 in the burnout zone is thus avoided. The material is transferred indirectly by heat radiation from the surface of the fire protection internals 43 into the material. The fire protection internals 43, the throwing plates 44, and the rotary kiln 9 as a whole are made of heat-resistant and wear-resistant material.

[0093] The following is Fig. 5 to 7, the structure and function of the swirling element 35 are explained in more detail. The swirling element 35 is designed as a baffle plate. The essential function of the baffle plate 35 is to tangentially swirl the air arriving along the longitudinal axis 26, i.e. the primary air. The baffle plate 35 is arranged concentrically to the longitudinal axis 26 in the burner housing 27. The baffle plate 35 has a plurality of blades 53, 54. The inner blades 53 are arranged in a circular manner in the circumferential direction around the longitudinal axis 26, overlapping one another. According to the exemplary embodiment shown, sixteen blades 53 are arranged. In a central region, which is surrounded by the inner blades 53, a central through-opening 55 remains. The inner blades 53 have a transverse web 56 that is oriented perpendicular to the longitudinal axis 26. The transverse web 56 is connected in one piece to a diagonal web 58 via the edge 57.The transverse web 56 and the diagonal web 58 enclose an opening angle which is greater than 90° and less than 180°, in particular between 120° and 150°.

[0094] The inner blades 53 are held in an inner ring 59. The inner ring 59 is enclosed by outer blades 54, which are held on their outside by an outer ring 60. The outer ring 60 protrudes in both directions in the axial direction relative to the longitudinal axis 26 on the inner ring 59. The outer blades 54 are designed, in particular, without any edging, thus having a flat, planar geometry. A central ring 61 is axially mounted on the outer blades 54, relative to the radical direction between the inner ring 59 and the outer ring 60. In the direction of the longitudinal axis 26, the baffle plate 35 has an inflow surface that is divided into three parts. The inflow surface comprises the inner central region, which is formed by the passage 55 and the inner blades 53 and is closed off by the inner ring 59. In this region, in particular, the second secondary fuel nozzle 34 for oil is arranged.A second section is formed in the radial direction between the inner ring 59 and the middle ring 61. In this area, the first secondary fuel nozzles 33 for gas, in particular natural gas, are arranged.

[0095] The outer blades 54 are oriented inclined relative to the longitudinal axis 26 and in particular are arranged in a plane which essentially corresponds to the plane of the corresponding diagonal webs 58 of the inner blades 53.

[0096] An outer, in particular annular section between the middle ring 61 and the outer ring 60 can be flowed against by the hydrogen nozzle 31 designed as an annular nozzle.

[0097] The following is based on Fig. 1 to 7, a method for drying material in the asphalt mixing plant 1 is explained in more detail.

[0098] In the first device 2, material can be fed to the rotary kiln 9 via the material inlet 10. The material is conveyed at the material inlet 10 along the material conveying direction 22 by means of conveying elements (not shown in detail), which are designed in particular as inlet screw segments and are attached to the inner wall of the rotary kiln. Due to the special design of the throwing plates 44, a dense, continuous, and homogeneous material veil 45 is created in the heat transfer area 21, so that the material is arranged with a very large surface area within the rotary kiln 9. The material can be heated by convection using the burner flame 13, which is arranged directly in the rotary kiln 9.

[0099] The burner flame 13 is generated by the burner 12, which is designed as a combination burner and burns hydrogen gas as its primary fuel. Natural gas and light oil are used in particular as secondary fuels. It is understood that other secondary fuels can also be used, in particular just one secondary fuel or more than two secondary fuels. The burner 12 can also be operated without secondary fuels and / or exclusively using secondary fuels. By using hydrogen gas as the primary fuel, exhaust gases and / or emissions are reduced and, in particular, avoided. By feeding exhaust gases and / or emission-laden air via the exhaust line 18 and co-combusting, an overall reduction in exhaust gases is achieved.

[0100] By arranging closed fire protection internals 43 in the burnout zone 20 in the rotary kiln 9, in which the burner flame 13 is located, direct material contact with the burner flame 13 is avoided. It is essential that the burner flame 13 can be precisely adjusted due to the geometry of the burner head 41 and / or the baffle plate 35, the number, arrangement, and design of the fuel nozzles 31, 33, and / or 34, so that it is located entirely within the burnout zone 20 in the rotary kiln 9. In particular, the cooling cone 36 and the annular gap 50 formed between the cooling cone 36 and the burner housing 27 create the prerequisite for air staging. Secondary air is guided past the baffle plate 35 and around the burner flame 13.

[0101] In particular, it is possible to keep the flame temperature as low as possible, especially at less than 1400°C, so that the formation of nitrogen oxides (NO x) is minimized and, in particular, avoided.

[0102] In order to be able to adjust the desired shape of the burner flame 13 depending on the fuels used, it may be advantageous to change the number, design, and / or position of the fuel nozzles 31, 33, and / or 34 relative to the baffle plate 35. In particular, it is possible to arrange individual and / or all nozzles 31, 33, and 34 behind the baffle plate 35 with respect to the gas conveying direction 23. The inner diameter D Iof the rotary kiln 9 is, in particular, selected such that the flow velocity of the resulting exhaust gas volume flows of the various fuels is so low that only filler, i.e., rock dust with a particle size of 200 µm or less, is discharged from the rotary kiln 9. In particular, the flow velocity is less than 20 m / s and, in particular, between 15 m / s and 20 m / s. It is advantageous if the flow velocity and / or the volume flow of the exhaust gas is kept low. This can reduce and, in particular, minimize wear in raw gas ducts and / or in an exhaust pipe. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 210 662.5

[0001]

Claims

[1] Device for drying material for an asphalt mixing plant, the device (2, 3) comprising a rotary kiln (9) which can be driven to rotate about a rotational axis (19) and in which the material is dried, the rotary kiln (9) having a material inlet (10) and a material outlet (11), b. a heating unit coupled to the rotary kiln (9) for supplying heat to the rotary kiln (9), the heating unit being designed with a burner (12) having i. a burner housing (27) having a longitudinal axis (26), ii. an air line (16) arranged on the burner housing (27) for supplying air, iii. a swirling element (35) for swirling the air in the burner (12) relative to the longitudinal axis (26), iv. a hydrogen gas line (14) connected to the burner (12) for supplying hydrogen gas into the burner (12), wherein a hydrogen gas nozzle (31) for discharging the hydrogen gas is connected to the hydrogen gas line (14), v. a burner head (41) arranged on the burner housing (27) for generating a burner flame (13), wherein the burner (12) can be operated exclusively by means of hydrogen gas. [2] Device according to claim 1, characterized by that the swirling element (35) comprises a flow guide element in the burner housing (27), wherein the flow element is arranged in particular stationary and in particular concentrically to the longitudinal axis (26). [3] Device according to claim 2, characterized by that the flow guide element is designed as a baffle plate which has a plurality of blades (53, 54) arranged in a circle with respect to the longitudinal axis (26) and oriented at an inclination. [4] Device according to one of the preceding claims, characterized by a cooling cone (36) arranged in the burner housing (27) and arranged along the longitudinal axis (26), in particular between the swirling element (35) and the burner head (41). [5] Device according to one of the preceding claims, characterized by a secondary fuel line (17) connected to the burner (12) for supplying secondary fuel, wherein in particular a secondary fuel nozzle (33, 34) for dispensing the secondary fuel is connected to the secondary fuel line (17). [6] Device according to one of the preceding claims, characterized by that the air line (16) is arranged axially to the longitudinal axis (26) on the burner housing (27), wherein in particular an air blower (29) is arranged in the air line (16, 28). [7] Device according to one of the preceding claims, characterized byan exhaust gas line (18) for supplying exhaust gases to the heating unit, in particular to the burner (12), and / or to the rotary kiln (9). [8] Device according to one of the preceding claims, characterized by that the heating unit comprises a hot gas generator (24) connected to the burner (12), wherein the hot gas generator (24) is connected to the rotary kiln (9) in particular by means of a hot gas line (25). [9] Device according to one of claims 1 to 7, characterized byin that the burner (12) is attached to the end face of the rotary kiln (9), in particular in the region of the material outlet (11), in particular is integrated directly into the rotary kiln (9), in particular such that the burner head (41) is arranged inside the rotary kiln (9), wherein in particular the rotary kiln (9) has, in particular, closed, fire protection fittings (43) which are arranged on an inner wall of the rotary kiln (9) and in particular are fastened thereto, and / or wherein in particular the rotary kiln (9) has, in particular, open throwing plates (44) which are arranged on an inner wall of the rotary kiln (9) and in particular are fastened thereto in order to produce a, in particular closed, material curtain (45) in the rotary kiln (9). [10] Device according to claim 9, characterized bythat the rotary kiln (9), in particular in the region of the material inlet (10), has at least one conveying element which is arranged on an inner wall of the rotary kiln (9) and in particular is fastened thereto in order to effect material transport along the axis of rotation (26). [11] Asphalt mixing plant with a device (2, 3) according to one of the preceding claims and in particular with a filter dedusting device (5) and / or in particular with a condensate separator (6), which are fluidically connected to the rotary kiln (9).

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