Installation and method for drying material for producing asphalt

Abstract

The invention relates to an installation (1) for drying material for producing asphalt, comprising a drying unit (2) for drying mineral and / or recycling asphalt, b. a heating unit which is connected to the drying unit (2) and has a hydrogen burner (4), a hydrogen source (13, 20, 21, 22) for providing hydrogen gas, and a controlled pressure system (14) connecting the hydrogen source (13, 20, 21, 22) and the hydrogen burner (4), wherein the controlled pressure system (14) has a processing pressure reducer (34), which is connected to the hydrogen burner (4) and comprises a low-pressure reducer (28) and / or a high-pressure reducer (26) for providing the hydrogen gas with processing pressure (pv) and for the multi-stage pressure relief of the hydrogen gas.

Description

[0001] Plant and process for material drying for the production of asphalt

[0002] The content of the German patent application DE 10 2024 202 664.6 is incorporated herein by reference.

[0003] The invention relates to a plant and a method for drying material for the production of asphalt.

[0004] DE 10 2021 210 662 A1 discloses an apparatus and method for drying material. A rotary kiln is supplied with heat from a heating unit. The heat is generated by a burner in which hydrogen gas is combusted. A gas control system supplies the hydrogen gas to the burner.

[0005] It is the object of the present invention to improve the provision of hydrogen gas for the production of asphalt and, in particular, to enable reliable and flexible coupling with a hydrogen source.

[0006] This object is achieved according to the invention by a system having the features specified in claim 1 and by a method having the features specified in claim 15.

[0007] According to the invention, it was recognized that hydrogen gas is provided by a hydrogen source under a pressure that is unsuitable for direct processing in a hydrogen burner. A system according to the invention comprises at least one hydrogen source and can in particular have a plurality of hydrogen sources, which can in particular be of the same type, in particular of the same construction, and in particular identical. The hydrogen sources can also be of different types. In order to provide the hydrogen gas for the hydrogen burner at a processing pressure, the hydrogen gas is depressurized in several stages. For this purpose, a high-pressure reducer and / or a low-pressure reducer as well as a processing pressure reducer are provided along a pressure control line. The processing pressure reducer is in particular arranged downstream of the low-pressure reducer.The high-pressure reducer is used to reduce the pressure of the hydrogen gas from a storage pressure at which the hydrogen gas is stored in the hydrogen gas pressure vessel to the intermediate pressure, also referred to as the pre-pressure, at which the hydrogen gas is made available at the low-pressure reducer. The hydrogen gas made available from the hydrogen gas pressure vessel is depressurized along the pressure control line, in particular in three stages, namely by means of the high-pressure reducer, the low-pressure reducer and the processing pressure reducer. The low-pressure reducer enables a pressure reduction from intermediate pressure to low pressure. The intermediate pressure is an overpressure compared to atmospheric pressure and amounts to at least 25 barg, in particular at least 30 barg, in particular at least 35 barg and in particular at least 40 barg.The low pressure is an overpressure relative to atmospheric pressure and amounts to at least 2.5 barg, in particular at least 3 barg, and in particular at least 4 barg. The processing pressure reducer enables a pressure reduction from the low pressure to the processing pressure. The processing pressure is an overpressure relative to atmospheric pressure and amounts to at least 0.2 barg, in particular at least 0.25 barg, and in particular at least 0.3 barg. The high-pressure reducer is arranged in particular upstream of the processing pressure reducer and in particular upstream of the low-pressure reducer.

[0008] It is also possible for the system to be designed without a high-pressure reducer, especially if the system is designed without a hydrogen gas pressure vessel. The hydrogen gas can be supplied using other hydrogen sources that provide the hydrogen gas at medium pressure, which can be reduced to low pressure using the medium-pressure reducer.

[0009] Alternatively, it is conceivable to design the system without a low-pressure reducer, especially if the hydrogen sources are provided exclusively by hydrogen gas pressure vessels. In this case, the high-pressure reducer is designed in such a way that the hydrogen gas supplied by the hydrogen gas pressure vessels at storage pressure is reduced to low pressure.

[0010] The plant according to the invention enables the reliable provision of hydrogen gas with a mass flow of at least 400 kg / h, in particular at least 500 kg / h and in particular at least 600 kg / h. Such large mass flows are particularly necessary when the plant is operated primarily, in particular mainly and in particular exclusively, with hydrogen gas as fuel gas. Such a large mass flow is additionally or alternatively required when the plant is operated at full load. This is the case when the current output of the plant is at least 80% of the nominal output of the plant, in particular at least 85%, in particular at least 90%, in particular at least 95%, in particular 100% or more. In particular, short-term operation of the plant under overload is also possible.

[0011] However, the system according to the invention can also provide smaller mass flows, in particular within a control range of 1:10. Smaller mass flows are particularly relevant when the system is operated at partial load and / or with mixed firing, i.e., hydrogen gas is only used partially as fuel gas. In such cases, the mass flow of hydrogen gas can be at least 40 kg / h, in particular at least 60 kg / h.

[0012] The system according to the invention provides hydrogen gas with a sufficiently large mass flow, which is advantageous for the economical and reliable continuous operation of the hydrogen burner. Because the pressure relief takes place in several stages according to the invention, large pressure jumps for the hydrogen gas can be avoided. In particular, this minimizes the pressure effect of a hydrogen gas supplier, which can occur particularly with variable inlet pressures when providing hydrogen gas from mobile storage containers. The risk of an interruption in the hydrogen gas supply is minimized. Continuous operation of the hydrogen burner, which is advantageous for continuous material drying, is ensured.

[0013] The system according to the invention makes it possible to provide large mass flows of hydrogen gas from, in particular, mobile pressure vessels, in a constant and reliable manner. In particular, it was recognized that the cooling of the hydrogen gas during expansion within the mobile pressure vessels and strongly varying inlet pressures and the resulting supply pressure effect, i.e. an increase in the downstream pressure with a falling inlet pressure, can be controlled. This allows the capacity of a mobile pressure reservoir to be better utilized. The efficiency of hydrogen gas utilization is increased. In particular, hydrogen gas from the mobile pressure reservoir can be used starting with an inlet pressure of, for example, 380 barg up to a residual pressure of at least 20 barg, in particular at least 30 barg and in particular at least 40 barg.In particular, this is made possible by designing and / or monitoring the relevant pressures and / or temperatures along the gas control line. In particular, the system according to the invention enables flexible connection and / or disconnection of individual hydrogen sources and, in particular, multi-stage pressure reduction.

[0014] The hydrogen burner is particularly suitable for being operated exclusively with hydrogen gas as the fuel gas. In particular, hydrogen gas is the primary fuel for the hydrogen burner. The hydrogen burner is suitable for burning up to 100% hydrogen gas. The hydrogen burner can in particular also be designed as a multi-fuel burner. If a secondary fuel is used in addition to hydrogen gas, the stoichiometric proportion of hydrogen gas in the fuel mixture is at least 10%, in particular at least 25%, in particular at least 30%, in particular at least 40%, in particular at least 50%, in particular at least 60%, in particular at least 70%, in particular at least 80%, in particular at least 90%, in particular at least 95% and in particular 100%. The hydrogen slurry burner is part of a heating unit that is connected to a drying unit.The heating unit can, in particular, be connected directly to the drying unit. In this case, the burner flame generated by the hydrogen burner is located directly in the drying unit. Alternatively, the heating unit can be designed such that the hydrogen burner is indirectly connected to the drying unit. For example, the hydrogen burner can be connected, in particular directly, to a hot gas generator, which generates hot gas that is fed to the drying unit via a hot gas line. In this case, indirect drying of material in the drying unit is possible. Indirect drying is particularly gentle on the material.

[0015] The drying unit is, in particular, a drying drum. The drying drum has, in particular, a cylindrical inner contour with a rotational axis and opposing end faces. The material to be dried is conveyed through the drying unit essentially along a material conveying direction that runs, in particular, parallel to the rotational axis. Heat is supplied, in particular, at one of the end faces of the drying drum. The heat propagation direction extends, in particular, along the rotational axis. Depending on the orientation of the material conveying direction and the heat propagation direction, the drying unit is operated in countercurrent or cocurrent flow. The drying unit is used, in particular, for drying minerals, i.e., rock, and / or recycled asphalt. Recycled asphalt is old asphalt that has been removed and reclaimed, for example, during road renovation.The use of reclaimed asphalt is economically and ecologically advantageous. To facilitate material transport through the drying drum, its rotational axis is inclined relative to a horizontal plane. The angle of inclination is, in particular, no more than 8°, in particular no more than 5°, in particular no more than 3°, and in particular no less than 1°.

[0016] A system according to claim 2 ensures reliable and, in particular, self-sufficient operation of the material drying system. It has been shown that hydrogen gas can be stored reliably and safely, at least temporarily, in a pressure vessel. Hydrogen gas is stored in the hydrogen gas pressure vessel under storage pressure. The storage pressure is an excess pressure relative to atmospheric pressure of at least 200 barg, in particular at least 350 barg, in particular at least 380 barg, and in particular at least 500 barg. The storage pressure is also referred to as high pressure. A hydrogen gas pressure vessel enables the storage of up to 1200 kg of hydrogen gas. In particular, several hydrogen gas pressure vessels can be connected to the pressure control line in parallel.Taking into account the residual pressure required in the hydrogen gas pressure vessel, for example, up to 4000 kg of hydrogen gas or more can be stored and made available directly at the plant.

[0017] In particular, several connections, in particular at least three, in particular at least four, are provided for the parallel connection of hydrogen gas pressure vessels to the pressure control line. The hydrogen gas pressure vessels are of the same type and in particular of identical construction. In particular, the hydrogen gas pressure vessels are identical. With several hydrogen gas pressure vessels, a redundant supply of hydrogen gas is possible. It is in particular possible for hydrogen gas to be supplied from a first hydrogen gas pressure vessel while a second hydrogen gas pressure vessel is being refilled with hydrogen gas. The redundant arrangement enables repair, maintenance and / or cleaning work to be carried out on one of the hydrogen gas pressure vessels without having to interrupt the operation of the system. The redundant arrangement of the hydrogen gas pressure vessels ensures uninterrupted operation of the material drying process.

[0018] A shut-off valve according to claim 3 increases the overall safety of the system. The shut-off valve allows the hydrogen gas pressure vessel to be fluidically separated from the pressure control line, particularly directly and reliably. In particular, each hydrogen gas pressure vessel is assigned a separate shut-off valve.

[0019] The arrangement of the high pressure reducer according to claim 4 improves the utilization of hydrogen gas from the hydrogen gas pressure vessel.

[0020] The design of the hydrogen source according to claim 5 opens up additional hydrogen supply possibilities. In particular, the hydrogen source is different from a hydrogen gas pressure vessel. The hydrogen source provides the hydrogen gas under medium pressure, which is in particular lower and in particular significantly lower than the storage pressure of the hydrogen gas pressure vessel. The hydrogen gas provided by the hydrogen source under medium pressure is pressure-reduced in two stages along the pressure control line, namely by means of a low-pressure reducer and the processing pressure reducer. The hydrogen source can, for example, be designed as a hydrogen gas supply line, which is in particular directly connected to the pressure control line. The hydrogen gas supply line can be part of a hydrogen gas pipeline network. The hydrogen gas pipeline network can, for example, be a public hydrogen gas pipeline network.Alternatively, it can be a private, particularly company-owned, hydrogen gas pipeline network, especially at a larger production facility. A hydrogen gas supply line is also understood to mean a hydrogen gas pipeline interface to which, for example, a hydrogen transport vehicle, in particular a transport truck and / or transport train, can be connected for the delivery of hydrogen gas.

[0021] Additionally or alternatively, the hydrogen source can also comprise a hydrogen gas generation device, in particular at least one electrolyzer. The electrolyzer can generate hydrogen gas and oxygen from water using electrical current. The electrolyzer can be operated, in particular, using renewable electricity, in particular from wind power and / or solar power. Hydrogen gas generated in this way is referred to as "green hydrogen." For redundancy purposes, it is advantageous if several electrolyzers are arranged in parallel.

[0022] Additionally or alternatively, the hydrogen source may also comprise a hydrogen gas buffer tank in which hydrogen gas can be at least temporarily stored. In particular, the hydrogen gas buffer tank may also be arranged in combination with the hydrogen gas supply line and / or with the hydrogen gas generation device. In particular, the hydrogen gas buffer tank may be fed by the hydrogen gas supply line and / or the hydrogen generation device.

[0023] The connection of the hydrogen source according to claim 6 ensures reliable pressure reduction to low pressure.

[0024] A gas control line according to claim 7 enables particularly reliable operation of the system. The gas control line is particularly designed to be controllable. Along the gas line, the gas control line is arranged between the processing pressure reducer and the hydrogen burner. In particular, the gas control line is arranged directly upstream of the hydrogen burner.

[0025] The gas control line is used to regulate the burner inlet pressure and the amount of hydrogen gas supplied. Furthermore, the gas control line fulfills safety functions. The gas control line comprises, in particular, a filter, a pressure regulator, a safety shut-off valve, a safety relief valve, two main valves for safely isolating the fuel supply, and a flow control flap. The main valves are pneumatically operated. All other components are, in particular, electrically operated. The pressure control line is used, in particular, to regulate the pressure and / or to safely supply hydrogen gas. In particular, the gas control line is part of the pressure control line. In particular, the gas control line is integrated into the pressure control line.

[0026] A fuel main valve according to claim 8 enables reliable separation of the fuel supply downstream of the pressure control line. The fuel main valve is arranged, in particular, upstream of the processing pressure reducer and, in particular, downstream of the low-pressure reducer. The fuel main valve is designed, in particular, to be pneumatically actuated.

[0027] The fuel main valve reliably shuts off the fuel supply at the outlet of the pressure control line. The fuel main valve has a safety function. The fuel main valve is only open when the system is in a safe condition. A safe condition is determined, in particular, by monitoring pressures and / or temperatures. As soon as pressures and / or temperatures deviate from setpoints and / or value intervals, the fuel supply can be shut off using the fuel main valve. In particular, the fuel main valve is also signal-linked to an emergency shut-off and / or emergency stop in the burner control system.

[0028] An exhaust gas recirculation line according to claim 9 enables the recirculation of exhaust gases from the drying unit to the hydrogen burner. The exhaust gases can advantageously be used as secondary gas in the hydrogen burner to specifically influence and, in particular, slow down hydrogen combustion in order to avoid excessively high flame temperatures. The exhaust gas recirculation line is a fluidic connection from the drying unit, in particular from the outlet of the drying unit, to the hydrogen burner. In particular, the exhaust gas recirculation line is connected directly to the hydrogen burner. The exhaust gas recirculation line is, in particular, indirectly connected to the drying unit. In particular, the exhaust gases from the drying unit are first passed through a filter and an exhauster. In particular, the exhaust gas recirculation line is connected downstream of the exhauster in order to recirculate at least a portion of the purified exhaust gases to the hydrogen burner.

[0029] A burner control unit according to claim 10 simplifies automatic and in particular automated operation of the system. In particular, fully automated and controlled operation of the system is possible. In particular, the burner control unit can be integrated into a system control system of the system and in particular is integrated therein. In any case, the burner control unit is in a signal connection, in particular a bidirectional connection, with the system control system. The burner control unit enables the acquisition of input data for the control system. For this purpose, the burner control unit is in signal connection, in particular, with at least one pressure sensor, with at least one temperature sensor and / or with at least one hydrogen sensor. The at least one hydrogen sensor serves to detect the hydrogen concentration. For example, leaks and / or incomplete combustion can lead to hydrogen gas being released, in particular unintentionally.This allows a critical ignition limit to be reached, which is highly relevant to safety. The burner control unit ensures that the system is shut down reliably and safely before the ignition limit is reached. In particular, two hydrogen sensors are provided, which are connected, in particular directly, upstream and downstream of the drying unit. In order to transmit the control signals required for control, the burner control unit is in signal communication, in particular, with the shut-off valve, the main fuel valve, the valve train and / or the recirculation fan. A heat exchanger according to claim 11 promotes pressure relief along the gas control section. In particular, the heat exchanger is arranged downstream of the main fuel valve. In particular, several heat exchangers are provided, which are arranged, in particular, parallel to one another.The at least one heat exchanger serves to condition the hydrogen gas, particularly before it is introduced into the gas control system. Particularly low temperatures of the hydrogen gas during its introduction into the gas control system can be avoided. The heat exchanger is supplied with exhaust gas from an exhauster and / or a stack, which has a temperature of approximately 100 °C. The exhaust gas serves as a heat transfer medium. The exhaust gas is generated anyway. Preheating the expanded hydrogen gas is efficient, thus eliminating the need for additional energy consumption.

[0030] A gas meter according to claim 12 simplifies the direct monitoring of the mass flow of the hydrogen gas conveyed along the gas control line. The gas meter is arranged, in particular, downstream of the heat exchanger. Alternatively, the gas meter can also be arranged upstream of the heat exchanger. In particular, the gas meter can be arranged upstream, in particular directly upstream, of the low-pressure reducer.

[0031] A pressure relief valve according to claim 13 enables direct venting of the pressure control line. This increases the safety of the system. Unintentional pressure increases can be prevented. In particular, several pressure relief valves are provided, which are connected to the pressure control line in particular downstream of the processing pressure reducer, in particular downstream of the low-pressure reducer, and downstream of the high-pressure reducer. In particular, the pressure relief valves are each connected directly downstream of the pressure reducers. Additionally or alternatively, a pressure relief valve can also be connected directly to the hydrogen gas pressure vessel, in particular upstream of the respective shut-off valve. A pressure relief line is connected to the pressure relief valves, which enables venting to the environment, in particular in a safe area.

[0032] A secondary fuel source according to claim 14 enables reliable and, in particular, uninterrupted operation of the heating unit. The hydrogen burner is designed as a multi-fuel burner. The secondary fuels used are, in particular, oil, gas, especially natural gas, wood, and / or coal dust. The secondary fuels are each stored in a secondary fuel source and connected to the hydrogen burner via a suitable line.

[0033] A method according to claim 15 essentially has the advantages of the corresponding system, to which reference is hereby expressly made.

[0034] Both the features specified in the patent claims and the features specified in the following embodiment of a system according to the invention are suitable, either individually or in combination, for further developing the subject matter of the invention. The respective combinations of features do not represent any restrictions with regard to further developments of the subject matter of the invention, but are essentially merely exemplary in nature. Additional features, advantageous embodiments, and details of the invention will become apparent from the following description of an embodiment with reference to the drawing. These show:

[0035] Fig. 1 is a schematic view of a plant according to the invention for drying material for the production of asphalt.

[0036] A plant, shown purely schematically in Fig. 1 and designated as a whole by 1, is used for drying material for the production of asphalt. The plant 1 comprises a drying unit 2 in which the material, in particular mineral and / or recycled asphalt, is dried. The drying unit 2 is designed in particular as a drying drum. The drying drum is hollow-cylindrical and has a rotation axis 3 and oppositely arranged end faces.

[0037] A heating unit with a hydrogen burner 4 is directly connected to the drying unit 2. The hydrogen burner 4 supplies heat to one of the ends of the drying unit 2. The heat spreads through the drying unit 2 along the rotational axis 3. According to Fig. 1, the heat propagation direction is oriented from left to right. The material to be dried in the drying unit 2 passes through the drying unit 2 along a material conveying direction, which can be oriented either parallel to or opposite to the heat propagation direction. Accordingly, the drying unit 2 is operated in cocurrent or countercurrent flow.

[0038] The hydrogen burner 4 is designed as a multi-fuel burner. Several hydrogen sources 13, 20, 21, 22 and at least one secondary fuel source 5 are connected to the hydrogen burner 4. The secondary fuel source 5 is, in particular, a storage container, in particular a tank for oil or gas, and / or a solid container for wood, in particular wood pellets, or coal dust.

[0039] Downstream of the drying unit 2, an exhaust filter 7 and an exhaust port 8 for exhaust gas purification are connected to an exhaust line 6. A chimney 9 is connected to the exhaust port 8, through which the purified exhaust gas can be released into the environment.

[0040] An exhaust gas recirculation line 10 is connected to the exhaust gas line 6 to return, in particular purified, exhaust gas from the drying unit 2 to the hydrogen burner 4. A recirculation fan 11 is arranged along the exhaust gas recirculation line 10.

[0041] In particular, at least two hydrogen gas sensors 12 are connected to the drying unit 2 to monitor the hydrogen gas concentration. In particular, a first hydrogen gas sensor 12 is arranged on the front side of the drying unit 2 to which the hydrogen burner 4 is connected or to which the heat of the drying unit 2 is supplied. A second hydrogen gas sensor 12 is arranged on the opposite front side of the drying unit 2, in particular connected to the exhaust line 6. The hydrogen gas sensors 12 serve to monitor the hydrogen gas concentration in the inflow or outflow of the drying unit 2. The hydrogen gas sensors 12 enable a safety shutdown of the system 1 before the ignition limit of a gas mixture enriched with hydrogen gas is reached. The hydrogen gas sensors 12 enable an additional safety function. The system 1 comprises several, in particular four, hydrogen gas pressure vessels 13.The hydrogen gas pressure vessels 13 are hydrogen sources used to store hydrogen gas in system 1. Hydrogen gas is stored in the hydrogen gas pressure vessels 13 at storage pressure ps. According to the illustrated embodiment, the storage pressure is 380 barg. The hydrogen gas pressure vessels 13 are arranged parallel to one another and connected to a pressure control line designated as a whole by 14. The pressure control line connects the hydrogen gas pressure vessels 13 to the hydrogen burner 4.

[0042] In particular, each hydrogen gas pressure vessel 13 is assigned a shut-off valve 15, which is arranged along a fluid line 16 between the respective hydrogen gas pressure vessel 13 and the pressure control line 14. The shut-off valves 15 can be used to fluidically isolate the individual hydrogen gas pressure vessels 13 from the pressure control line 14.

[0043] A purge valve 17 is arranged on each hydrogen gas pressure vessel 13 and connected to a vent line 18. A pressure relief element 19 is connected to the vent line 18 to release hydrogen gas into the environment without risk.

[0044] As further hydrogen sources, the system 1 comprises, in particular, at least one hydrogen gas buffer tank 20, a hydrogen gas supply line 21, and / or a hydrogen gas generation device 22, in particular in the form of an electrolyzer. The hydrogen gas supply line 21 can comprise a public and / or private pipeline network. Additionally or alternatively, the hydrogen gas supply line 21 can have a line interface to which hydrogen gas storage containers, in particular mobile ones, can be connected. The hydrogen gas generation device 22 is operated, in particular, by means of electrical power, which has been generated, in particular, regeneratively. It is particularly conceivable for fluid lines to be led from the hydrogen gas supply line 21 and / or the hydrogen gas generation device 22 to the hydrogen gas buffer tank 20 in order to temporarily store hydrogen gas in the hydrogen gas buffer tank 20.

[0045] The hydrogen sources 20, 21, and 22 provide hydrogen gas at medium pressure PM. According to the illustrated embodiment, the medium pressure PM is 35 barg. The hydrogen sources 20, 21, and 22 are connected to the pressure control line 14 via a high-pressure line 23. The pressure control line 14 also connects the hydrogen sources 20, 21, and 22 to the hydrogen burner 4.

[0046] The pressure control line 14 specifies a gas conveying direction 24 which is directed from the hydrogen sources 13, 20, 21, 22 to the hydrogen burner 4.

[0047] The pressure control section 14 comprises a hydrogen gas line 25, to which the following components are connected along the gas conveying direction 24. The hydrogen gas pressure vessels 13 are connected to a high-pressure reducer 26 via the fluid lines 16. The high-pressure reducer 26 reduces the storage pressure ps to the intermediate pressure PM. Downstream of the high-pressure reducer 26 and in particular downstream of the connection of the high-pressure line 23 to the hydrogen gas line 25, a high-pressure relief valve 27 is arranged, which vents into the vent line 18, in particular at an overpressure of 50 barg. Downstream of the high-pressure reducer 26, a low-pressure reducer 28 is arranged, with which the intermediate pressure PM of the hydrogen gas is reduced to a low pressure PN. According to the exemplary embodiment shown, the low pressure PN is an overpressure of 3 barg.Downstream of the low-pressure reducer 28, a low-pressure relief valve 29 is arranged and connected to the hydrogen gas line 25. The low-pressure relief valve 29 vents into the vent line 18 at an overpressure of at least 5 barg.

[0048] Downstream of the low pressure reducer 28, a pneumatically actuated fuel main valve 30 is arranged.

[0049] At least one heat exchanger 31 is arranged downstream of the main fuel valve 30. According to the illustrated embodiment, two heat exchangers are provided, which are connected in parallel to the hydrogen gas line 25. The heat exchangers 31 are designed, in particular, as optional components. The heat exchanger 31 is designed, in particular, as a shell-and-tube heat exchanger, with exhaust gas at a temperature of approximately 100°C serving as the heat transfer medium, which is recirculated, in particular, from the dust removal system and / or the stack into the heat exchanger.

[0050] A gas meter 32 and a hydrogen gas filter 33 are arranged downstream of the heat exchanger 31. The hydrogen gas filter 33 is designed, in particular, as a cellular gas filter. The gas meter 32 is optional.

[0051] A processing pressure reducer 34 is arranged downstream of the hydrogen gas filter 33. The processing pressure reducer 34 reduces the hydrogen gas from the low pressure PN to a processing pressure pv. According to the illustrated embodiment, the processing pressure pv has an overpressure of 0.3 barg. At the processing pressure pv, the hydrogen gas can be fed to the hydrogen burner 4 and combusted there.

[0052] A gas control line 35 is arranged between the processing pressure reducer 34 and the hydrogen burner 4. The gas control line 35 is particularly designed to be controllable and is connected to a burner control unit 37 via a signal connection line 36. The signal connection line 36 is represented in Fig. 1 by a dashed-dotted line.

[0053] The burner control unit 37 is particularly integrated and has a signal connection to a higher-level system control system 38. The burner control unit 37 is also connected by signal to the hydrogen gas sensors 12, to temperature sensors 39, and to pressure sensors 40, which are arranged along the gas control section 14, in particular upstream of the low-pressure reducer 28, the main fuel valve 30, and the gas meter 32, and / or along the fluid line 16, in particular upstream of the respective shut-off valves 15. It is understood that additional temperature and / or pressure sensors (not shown in Fig. 1) may be present in order to be able to determine additional input data for the burner control unit 37.

[0054] To transmit control signals, the burner control unit 37 is in signal communication with the shut-off valves 15, the main fuel valve 30, the valve train 35, and / or the recirculation blower 11. System 1 can be divided into different pressure zones based on its pressure levels for the hydrogen gas. The hydrogen gas is present in a storage pressure zone 41 at the storage pressure ps. The storage pressure zone extends from the hydrogen gas pressure vessels 13 to the high-pressure reducer 26.

[0055] High-pressure zone 42 adjoins storage pressure zone 41. In high-pressure zone 42, the hydrogen gas is present at medium pressure PM. High-pressure zone 42 is defined on the inlet side by high-pressure reducer 26 and on the outlet side by low-pressure reducer 28.

[0056] The high-pressure zone 42 is followed by the low-pressure zone 43. In the low-pressure zone 43, the hydrogen gas is present at the low pressure PN. The low-pressure zone 43 extends from the inlet side of the low-pressure reducer 28 to the outlet side of the processing pressure reducer 34.

[0057] The low-pressure zone 43 is followed by the processing pressure zone 44. In the processing pressure zone 44, the hydrogen gas is present at the processing pressure pv. The processing pressure zone 44 extends on the inlet side from the processing pressure reducer 34 to the hydrogen burner 4.

[0058] The operation of Plant 1, a process for drying material for the production of asphalt, is explained in more detail below.

[0059] Hydrogen gas is made available from one of the hydrogen gas pressure vessels 13 at storage pressure ps. The hydrogen gas is fed to the high-pressure reducer 26 via the fluid line 16, where its pressure is reduced to medium pressure pM. Additionally or alternatively, hydrogen gas can also be made available from the hydrogen sources 20, 21, and / or 22 at medium pressure pM. In the low-pressure reducer 28, the medium pressure pM is then reduced to low pressure PN. The hydrogen gas is then fed to the processing pressure reducer 34 via the main fuel valve 30, the heat exchanger 31, the gas meter 32, and the hydrogen gas filter 33. The processing pressure reducer 34 reduces the pressure of the hydrogen gas to the processing pressure pv. At the processing pressure pv, the hydrogen gas is fed to the hydrogen burner 4 via the gas control line 35.

[0060] Heat is generated in the hydrogen burner 4 by at least partially combusting hydrogen gas. In addition, secondary fuels from one of the secondary fuel sources 5 can be combusted. The heat generated in the hydrogen burner 4 is either released directly into the drying unit 2 or indirectly via a hot gas generator (not shown). Exhaust gas generated in the drying unit 2 is conducted via the exhaust line 6 through the exhaust filter 7 and the exhaust port 8. The purified exhaust gas can be released into the environment via the chimney 9 and / or recirculated to the hydrogen burner 4 via the exhaust recirculation line 10.

[0061] Advantageous control of system 1 is achieved by means of the burner control unit 37.

Claims

Patent claims 1. Plant for material drying for the production of asphalt, comprising a. a drying unit (2) for drying mineral and / or recycled asphalt, b. a heating unit connected to the drying unit (2) and comprising a hydrogen slurry tank (4), c. a hydrogen source (13, 20, 21, 22) for providing hydrogen gas, d. a pressure control line (14) connecting the hydrogen source (13, 20, 21, 22) and the hydrogen slurry tank (4), characterized in that the pressure control line (14) e. has a processing pressure reducer (34) which is connected to the hydrogen burner (4) for providing the hydrogen gas at processing pressure (pv), f. has a low-pressure reducer (28) and / or a high-pressure reducer (26) for multi-stage pressure relief of the hydrogen gas.

2. Plant according to claim 1, characterized in that the hydrogen source comprises at least one hydrogen gas pressure vessel (13) in which hydrogen gas is stored under storage pressure (ps).

3. Plant according to claim 2, characterized by a shut-off valve (15) arranged along a fluid line (16) between the at least one hydrogen gas pressure vessel (13) and the pressure control line (14).

4. Plant according to one of the preceding claims, characterized in that the high-pressure reducer (26) is arranged along the pressure control section (14) upstream of the low-pressure reducer (28).

5. Plant according to one of the preceding claims, characterized in that the hydrogen source comprises at least one hydrogen gas buffer tank (20), a hydrogen gas supply line (21) and / or a hydrogen gas generating device (22), in particular an electrolyzer, wherein the hydrogen source (20, 21, 22) provides hydrogen gas under medium pressure (PM).

6. Plant according to claim 5, characterized in that the hydrogen source (20, 21, 22) is connected to the pressure control line (14) upstream of the low-pressure reducer (28).

7. Plant according to one of the preceding claims, characterized in that a, in particular controllable, gas control section (35) is arranged along the pressure control section (14) between the processing pressure reducer (34) and the hydrogen burner (4).

8. Plant according to one of the preceding claims, characterized in that a fuel main valve (30), in particular a pneumatically actuated and / or controllable one, is arranged along the pressure control section (14), in particular upstream of the processing pressure reducer (34).

9. Plant according to one of the preceding claims, characterized by an exhaust gas recirculation line (10) for recirculating exhaust gases from the drying unit (2) to the hydrogen burner (4), wherein a recirculation fan (11) is arranged along the exhaust gas recirculation line (10).

10. Plant according to one of the preceding claims, characterized by a burner control unit (37) for controlling the operation of the hydrogen burner (4), wherein the burner control unit (37) is in signal connection in particular with at least one pressure sensor (39), with at least one temperature sensor (40) and / or with at least one hydrogen gas sensor (12) for detecting input data and / or in particular with the shut-off valve (15), with the main fuel valve (30), with the gas control section (35) and / or with the recirculation blower (11) for transmitting control signals.

11. Plant according to one of the preceding claims, characterized by a heat exchanger (31) arranged along the pressure control section (14) between the low-pressure reducer (28) and the processing pressure reducer (34).

12. Plant according to one of the preceding claims, characterized by a gas meter (32) arranged upstream of the processing pressure reducer (34).

13. System according to one of the preceding claims, characterized in that a pressure relief valve (27, 29) is connected, in particular directly, downstream of the low-pressure reducer (28) and / or downstream of the high-pressure reducer (26).

14. Plant according to one of the preceding claims, characterized in that at least one secondary fuel source (5) is connected to the hydrogen burner (4).

15. Process for drying material for the production of asphalt, comprising the process steps Providing hydrogen gas from a hydrogen source (13, 20, 21, 22), Generating heat by means of a heating unit comprising a hydrogen burner (4) which is connected to the hydrogen source (13, 20, 21, 22) by means of a pressure control line (14), drying mineral and / or recycled asphalt in a drying unit (2) connected to the heating unit, characterized in that the hydrogen gas is pressure-reduced along the pressure control line (14) by means of a low-pressure reducer (28) from medium pressure (PM) to low pressure (PN) and / or by means of a high-pressure reducer (26) from storage pressure (ps) to medium pressure (PM) and by means of a processing pressure reducer (34) to processing pressure (pv) in order to provide the hydrogen gas at processing pressure (pv).

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