Retrofit system for providing heated reclaimed asphalt granulate, and plant for producing asphalt using such a retrofit system

Abstract

The invention relates to a retrofit system for providing heated reclaimed asphalt granulate, said system comprising: a reclaimed asphalt drying drum (16) having a reclaimed asphalt feed opening (18), a reclaimed asphalt discharge opening (19), a hot gas feed opening (21) for feeding hot gas into the reclaimed asphalt drying drum (16), and an exhaust gas discharge opening (22) for discharging exhaust gas from the reclaimed asphalt drying drum (16); a hot gas generator (27) having a cold gas feed opening (29), a hot gas discharge opening (30), and a heat source (32), the hot gas generator (27) being connected to the hot gas feed opening (21) by a hot gas line (31); an exhaust gas extraction unit (23), connected to the reclaimed asphalt drying drum (16), for extracting exhaust gas, the exhaust gas extraction unit (23) having a housing (24), a return line (26) which is connected to the housing (24) and is connected to the cold gas feed opening (29) of the hot gas generator (27) in order to return exhaust gas, a fan (28) arranged along the return line (26), and an exhaust air line (25) which is connected to the housing (24) and can be connected to a filter system (12); and a control unit (33) which is designed to discharge reclaimed asphalt granulate at a variably definable target temperature at the reclaimed asphalt discharge opening (19), the control unit (33) having a signal connection to the reclaimed asphalt drying drum (16), to the hot gas generator (27), and to the exhaust gas extraction unit (23).

Description

[0001] Retrofit system for providing heated old asphalt granulate and plant for producing asphalt with such a retrofit system

[0002] The content of the German patent application DE 10 2023 202 715.1 is incorporated herein by reference.

[0003] The invention relates to a retrofit system for providing heated old asphalt granulate and to a plant for producing asphalt with such a retrofit system.

[0004] Asphalt production plants, especially continuous mixing plants, have been around for a long time. In such plants, white mineral is mixed with other components to create an asphalt formulation. For ecological and economic reasons, it is desirable to use reclaimed asphalt, particularly to increase the proportion of reclaimed asphalt, which is also known as recycled asphalt or reclaimed asphalt. Existing asphalt production plants are often unsuitable for this purpose. Building a new, suitable plant is very complex and not cost-effective.

[0005] The invention is based on the object of enabling the use of old asphalt granulate in the production of asphalt in an asphalt production plant in a cost-effective manner.

[0006] This object is achieved according to the invention by a retrofit system having the features of claim 1 and by a plant having the features of claim 8. The core of the invention is that a retrofit system is suitable, on the one hand, for providing heated old asphalt granulate for further processing, and, on the other hand, can be easily and inexpensively integrated into an existing asphalt production plant. The retrofit system can directly enhance the functionality of the asphalt production plant.

[0007] A key finding of the invention is that the retrofit system itself comprises its own control unit, which is designed to provide old asphalt granulate with a variably definable target temperature. The target temperature is in particular between 120°C and 200°C, in particular between 130°C and 180°C and in particular between 160°C and 180°C. The control unit is designed separately from a system control of the system. The control unit of the retrofit system is in particular designed independently of the system control of the system. In particular, there is no signal connection between the control unit of the retrofit system and the system control. The control unit of the retrofit system and the system control are in particular logically separated from one another. Control-related obstacles regarding the integration of the retrofit system into the system are avoided from the outset.In particular, it was recognized that the inherently uncomplicated control system of the asphalt production plant can remain unchanged. Intervention in the existing and functioning control system is unnecessary. The comparatively more complex control of the retrofit system is solved by the control unit. External influences, which could arise in particular from the plant control system, are avoided when designing and programming the complex control system. Integration of the control unit into the plant control system is unnecessary. The effort required to integrate the control unit of the retrofit system into the plant control system is avoided.It may nevertheless be advantageous to establish a signal connection between the control unit of the retrofit system and the system control system, for example, to exchange operating parameters during system operation and, for example, to provide measured values ​​from the retrofit system as input variables for controlling and / or regulating the system in the system control system. Accordingly, measured parameters from the system control system could be incorporated into the control unit of the retrofit system. In particular, the signal transmission between the system control system and the control unit of the retrofit system is bidirectional.

[0008] The integration of the retrofit system into the asphalt production plant is straightforward and straightforward. The connection of the retrofit system according to the invention to the plant is essentially "plug-and-play."

[0009] The retrofit system features a reclaimed asphalt drying drum in which reclaimed asphalt granules are dried. The reclaimed asphalt granules are conveyed through the reclaimed asphalt drying drum along a reclaimed asphalt conveying direction. The reclaimed asphalt granules are gently heated and dried using hot gas generated in a hot gas generator. The hot gas is passed through the reclaimed asphalt drying drum, in particular in countercurrent to the conveying direction of the reclaimed asphalt. The hot gas can also be passed through the reclaimed asphalt drying drum in cocurrent. In particular, a hot gas supply opening is arranged on the end face of the reclaimed asphalt drying drum. In the hot gas generator, cold gas is heated by a heat source, which is designed in particular as a burner, in particular in countercurrent, and is discharged to the reclaimed asphalt drying drum via a hot gas line.The cold gas used is, in particular, cold or only slightly heated gas with a temperature between 80°C and 120°C, especially between 90°C and 110°C, and especially at 100°C, particularly exhaust gas from the old asphalt drying drum, which is recirculated to the hot gas generator via a return line. At least one fuel, in particular a gaseous, liquid, and / or solid fuel, is combusted in the burner. The heat source is arranged, in particular, at the front of the hot gas generator.

[0010] Because the reclaimed asphalt granules are indirectly heated using hot gas in the reclaimed asphalt drying drum, the heating process is particularly gentle. The resulting reclaimed asphalt granules are robust. The reject rate is low. In particular, the gentle heating process reduces total carbon (VOC) emissions. In particular, it has been recognized that peak temperatures that affect the bitumen components in the reclaimed asphalt granules can be avoided.

[0011] The retrofit system features an exhaust extraction unit for extracting exhaust gas from the old asphalt drying drum. At least a portion of the extracted exhaust gas is recirculated to the hot gas generator via a return line, where it is burned. The proportion of harmful exhaust gases, particularly carbon monoxide and / or total organic carbon (VOC), is reduced. The retrofit system is environmentally friendly. The exhaust extraction unit features an exhaust air line that can be connected to a filter unit. In particular, the exhaust extraction unit ensures that the exhaust gas discharged via the exhaust air line can be provided with a constant negative pressure and a moderate exhaust gas temperature. A constant negative pressure can be generated, in particular, by an exhauster connected to a filter system. The magnitude of the negative pressure can be varied depending on the system's operating point.The negative pressure is regulated in particular by means of a throttle, which is arranged in particular in an exhaust air duct connected to the filter system. Additionally or alternatively, an exhaust air fan can be present, which is connected in particular to the exhaust air duct. If the exhaust fan output is too low, the exhaust air fan can generate a required constant negative pressure. A moderate exhaust gas temperature is set as low as possible and can be varied, but in any case higher than the respective dew point. The exhaust gas temperature is influenced by the heat transfer in the drying drum. The heat transfer depends on the drum internals, the mass flow through the drying drum and / or the speed of the drying drum. The exhaust gas temperature is in particular at least 90°C, in particular at least 100°C and in particular at least 130°C.In particular, the exhaust gas temperature can be adjusted depending on the fuel used and / or the material to be dried. It has been found, in particular, that sulfur content in the exhaust gas can influence the dew point.

[0012] The retrofit system can be directly connected to a filter system in the asphalt production plant. The retrofit system features a straightforward exhaust interface.

[0013] The retrofit system's control unit is connected by signal to the old asphalt drying drum, the hot gas generator, and the exhaust gas extraction unit. The signal connections to the control unit are bidirectional. The signal connections can be wired or wireless, particularly via radio.

[0014] A signal connection is particularly advantageous for the pre-metering system for feeding the old asphalt granulate, in particular for feed units such as discharge belts or collecting belts. Furthermore, signal connections are advantageous for the exhaust air fan on the exhaust air line, for a recirculation fan, which is particularly mounted as a blower on a return line, for a white mineral heat source or for a heat source for the hot gas generator, in particular for corresponding burner actuators, burner blowers and / or air control dampers. Signal connections are also advantageous for various sensors, in particular for a material shortage switch, particularly in the material feed unit and / or the material discharge unit, as well as for vacuum sensors and / or temperature sensors in the drum outlet, on an exhaust air duct, a recirculation duct and / or a hot gas duct.

[0015] A material feed unit according to claim 2 simplifies the automated operation of the retrofit system.

[0016] An elevator according to claim 3 enables the material to be fed into the old asphalt drying drum from above.

[0017] Alternatively, the material can also be fed using a scraper belt.

[0018] It is essential that the reclaimed asphalt material is conveyed with as few deflections as possible once the reclaimed asphalt granulate has been heated. In particular, conveying is primarily gravimetric, and especially exclusively gravimetric. Therefore, it is advantageous if the reclaimed asphalt granulate is added to the reclaimed asphalt drying drum starting from a certain initial height. The material can be fed through a housing of an exhaust extraction unit. Alternatively, the material can also be fed past the housing of the exhaust extraction unit.

[0019] A dosing element according to claim 4 enables material flow control, in particular a variably determined mass flow of the old asphalt granulate. The dosing element is designed, in particular, as a conveyor belt, which can be designed, in particular, to be speed-controlled. In particular, the dosing element is in signal communication with the control unit.

[0020] A retrofit system according to claim 5 simplifies the automated and, in particular, controlled addition of quantities.

[0021] A retrofit system according to claim 6 simplifies the discharge of the heated old asphalt granulate into the asphalt production plant. A chute is designed in a simple manner and enables the old asphalt granulate to be discharged directly, in particular by gravity. The chute is arranged at an angle of inclination relative to the horizontal. The angle of inclination is in particular at least 50°, in particular at least 60°, and in particular 90°. The material discharge unit enables the material to be discharged in a straightforward manner, in particular to a mixing unit. The mixing unit is designed in particular as a double drying drum and / or as a forced-action mixer. The material discharge unit additionally or alternatively enables the material to be discharged, for example, onto a scraper belt and / or directly into a storage container, for example a loading silo.

[0022] A retrofit system according to claim 7 enables its autonomous operation. In particular, the retrofit system can be operated independently of the asphalt production plant. Exhaust gases are discharged via the exhaust air duct to a separate filter unit of the retrofit system, where they are cleaned. An external filter is unnecessary. The retrofit system can be used for heating old asphalt granulate without the asphalt production plant.

[0023] A system according to claim 8 is designed in a straightforward manner and, in particular, can be directly retrofitted with the retrofit system. The system essentially exhibits the advantages of the retrofit system, to which reference is hereby made.

[0024] A plant according to claim 9 enables the uncomplicated delivery of produced asphalt.

[0025] A system according to claim 10 enables at least temporary storage of finished asphalt at the plant. This is achieved, in particular, by a storage tank, which can be arranged stationary at the plant. Alternatively, a storage tank can also be mobile and transported by a transport vehicle, in particular a transport truck. A system according to claim 11 is compact and efficient. Exhaust gases from the retrofit system can be efficiently cleaned in the existing filter system. This does not result in any additional expenditure.

[0026] Both the features specified in the patent claims and the features specified in the exemplary embodiment of a retrofit system 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 the further development of the subject matter of the invention, but are essentially merely exemplary in nature.

[0027] Further features, advantages, and details of the invention will become apparent from the following description of an embodiment with reference to the drawings. They show:

[0028] Fig. 1 is a perspective view of an asphalt production plant with a retrofitting system according to the invention,

[0029] Fig. 2 is a plan view of the system according to Fig. 1.

[0030] A plant, designated overall by 1 in Fig. 1, is used to produce asphalt. Plant 1 is a continuous plant in which a continuous mass flow of manufactured asphalt is produced. Plant 1 could also be a discontinuous plant in which asphalt is produced in batches, in what is known as a batch operation. The plant has a white mineral drying drum 2 in which white mineral is heated and thereby dried. The white mineral drying drum 2 is essentially cylindrical with respect to a white mineral drying drum rotation axis 3. The white mineral drying drum 2 is designed to be rotatable about the white mineral drying drum rotation axis 3.

[0031] At a first end, shown on the left in Fig. 2, the white mineral drying drum 2 has a white mineral feed opening 4 through which white mineral can be fed into the white mineral drying drum 2. For this purpose, a white mineral feed device 5, shown purely schematically in Fig. 2, can be provided. In Fig. 2, the white mineral feed opening 4 is arranged at the end of the white mineral drying drum 2. A white mineral discharge opening 6 is arranged along the white mineral drying drum rotation axis 3 at a distance from the white mineral feed opening 4, through which the heated white mineral is discharged from the white mineral drying drum 2. The white mineral feed opening 4 and the white mineral discharge opening 6 define a white mineral conveying direction 7 that is oriented along the white mineral drying drum rotation axis 3.

[0032] A white mineral heat source 8 is arranged on the white mineral drying drum 2, in particular attached to the front of the white mineral drying drum 2. In particular, the burner is arranged adjacent to the white mineral feed opening 4 on the white mineral drying drum 2. The white mineral heat source 8 is a burner with which gaseous fuel, liquid fuel, and / or solid fuel can be combusted. The burner is arranged in particular concentrically with respect to the white mineral drying drum's rotational axis 3 and is attached to the front of the white mineral drying drum 2. The white mineral is heated in the white mineral drying drum 2 in cocurrent flow. Heating can also occur in countercurrent flow or crosscurrent flow.

[0033] The white mineral discharge opening 6 opens into a mixing unit 9, in which the heated white mineral is mixed with at least one other component and processed into asphalt. The mixing unit 9 is, in particular, a continuous mixing unit. The mixing unit 9 is, in particular, designed as a double drying drum, in which aggregates are fed to the double drying drum and mixed in an outer annular channel that is annular in a plane perpendicular to the drying drum's rotation axis 3. Alternatively, the mixing unit can be designed as a forced-action mixer, in particular with a movable drum and stationary mixing tools, or as a double-shaft forced-action mixer with fixed troughs and movable mixing tools.

[0034] An asphalt delivery unit 10 in the form of a conveyor belt, in particular a scraper belt, is connected to the mixing unit 9. The asphalt delivery unit 10 serves for the, in particular continuous, delivery of the asphalt, in particular for conveying the delivered asphalt from the mixing unit 9. The asphalt delivery unit 10 opens into a connected storage container 11 in order to at least temporarily store the produced asphalt. According to the exemplary embodiment shown, the storage container 11 is designed as a loading silo. The storage container 11 can also be mobile, in particular for transport on a transport truck. A filter system 12 is connected to the white mineral drying drum 2 via an exhaust air line 13. In the filter system 12, dust particles are filtered out of the exhaust air from the white mineral drying drum 2.The purified air can be released into the environment via an exhauster and / or chimney (not shown).

[0035] Plant 1 has a purely schematically illustrated plant control system 14. The plant control system 14 is in signal communication, particularly bidirectional, with the essential components of plant 1, particularly with the white mineral drying drum 2, the white mineral feed device 5, the white mineral heat source 8, and / or the mixing unit 9. The plant control system 14 enables the production of a continuous mass flow of asphalt with specified properties. The signal connections from the plant control system 14 to the aforementioned components are primarily wired, but can also be wireless, for example, via radio. The plant control system 14 is designed to be straightforward.

[0036] A retrofit system, designated overall by 15, is integrated into system 1. The retrofit system 15 comprises a reclaimed asphalt drying drum 16 in which reclaimed asphalt granulate is heated and thereby dried. The reclaimed asphalt drying drum 16 is essentially cylindrical with respect to a reclaimed asphalt drying drum longitudinal axis 17 and has a reclaimed asphalt feed opening 18 and a reclaimed asphalt discharge opening 19 arranged at a distance therefrom along the reclaimed asphalt drying drum longitudinal axis 17. The reclaimed asphalt feed opening 18 and the reclaimed asphalt discharge opening 19 define a reclaimed asphalt conveying direction 20 along the reclaimed asphalt drying drum longitudinal axis 17.The old asphalt drying drum 16 has a hot gas feed opening 21 and an exhaust gas discharge opening 22 on each of the opposite end faces. Hot gas is fed into the old asphalt drying drum 16 via the hot gas feed opening 21 and the old asphalt granulate is heated in countercurrent to the old asphalt conveying direction 20.

[0037] An exhaust gas extraction unit 23 with a housing 24 is connected to the exhaust gas discharge opening 22, which is formed in particular by the open end of the old asphalt drying drum 16. Exhaust gas from the old asphalt drying drum 16 is extracted by the exhaust gas extraction unit 23 and discharged to the filter system 12 via an additional exhaust air line 25. The exhaust air line 25 is connected to the filter system 12. It is essential that the exhaust air line 25 can be connected to the filter system 12 and / or to a separate filter unit.

[0038] Additionally or alternatively, the exhaust gas extracted from the old asphalt drying drum 16 by the exhaust gas extraction unit 23 is returned to a hot gas generator 27 via a return line 26. A fan 28 is arranged along the return line 26 to ensure a constant exhaust gas flow via the return line 26 into the hot gas generator 27.

[0039] Regarding the design and function of the exhaust gas extraction unit, explicit reference is made to DE 10 2015 217 845 Al.

[0040] The hot gas generator 27 has a cold gas supply opening 29, to which the return line 26 is connected. Furthermore, the hot gas generator 27 has a hot gas discharge opening 30, to which a hot gas line 31 is connected, in order to transfer hot gas generated in the hot gas generator 27 to the old asphalt drying drum 16. The cold gas supply opening 29 and the hot gas discharge opening 30 are each arranged in a region of the cylinder jacket surface, in particular at a distance from the oppositely arranged end faces of the cylindrical hot gas generator 27. A heat source 32 is connected to the hot gas generator 27 on the end face of the hot gas generator 27 adjacent to the hot gas discharge opening 30. The heat source 32 is designed, in particular, as a burner, which is designed to burn gaseous, liquid and / or solid fuel. In the hot gas generator 27, hot gas is generated in countercurrent.

[0041] With regard to the structure and function of the hot gas generator 27, explicit reference is made to DE 10 2015 217 845 A1.

[0042] The retrofit system 15 has a control unit 33, shown purely schematically in Fig. 2, which serves to control and / or regulate the operation of the retrofit system 15. It is important that the control unit 33 is designed exclusively for the control and / or regulation of the retrofit system 15 and in particular cannot be used to control and / or regulate the system 1. In particular, the control unit 33 is designed to be separate from the system control 14 in terms of control technology. In particular, there is no signal connection between the control unit 33 and the system control 14. For the integration of the retrofit system 15 into the system 1, it is therefore not necessary to modify and / or expand the system control 14. This results in significant control advantages for the retrofit system 15 and thus for the system 1 as a whole.The control unit 33 is in signal communication, in particular bidirectional, with the old asphalt drying drum 16, the exhaust gas extraction unit 23, and / or with the hot gas generator 27. A material feed unit 34, which in particular has an elevator 35 that opens into the old asphalt feed opening 18, is used to feed the old asphalt granulate into the old asphalt drying drum 16. In particular, the material feed unit 34 is in signal communication with the control unit 33.

[0043] The old asphalt drying drum 16 has a material discharge unit 36 ​​connected to the old asphalt discharge opening 19. The material discharge unit 36 ​​enables uncomplicated and direct discharge of the heated asphalt granulate into the mixing unit 9. The material discharge unit 36 ​​opens, in particular, into the mixing unit 9. The material discharge unit 36 ​​has, in particular, a chute arranged with respect to a horizontal plane at an angle of inclination of at least 50° and, in particular, at least 90°.

[0044] Because the retrofit system 15 can be separately controlled or regulated by means of the control unit 33, the retrofit system 15 enables the uncomplicated provision of heated old asphalt granulate, which can be delivered to the mixing unit 9 at a variably preset target temperature of, for example, 160°C, in particular with a variably definable mass flow. The system control system 14, which is already present, does not need to be modified by integrating the retrofit system 15. Retrofitting is thus significantly simplified. System 1 can be easily retrofitted with the retrofit system 15. The functionality of system 1 with the retrofit system 15 is fundamentally expanded.

Claims

Patent claims 1. Retrofit system for providing heated old asphalt granulate, comprising a. a old asphalt drying drum (16) with i. a old asphalt feed opening (18) and a old asphalt discharge opening (19), ii. a hot gas feed opening (21) for feeding hot gas into the old asphalt drying drum (16), iii. an exhaust gas discharge opening (22) for discharging exhaust gas from the old asphalt drying drum (16), b. a hot gas generator (27) with a cold gas feed opening (29), a hot gas discharge opening (30), and a heat source (32), wherein the hot gas generator (27) is connected to the hot gas feed opening (21) by a hot gas line (31), c. an exhaust gas extraction unit (23) connected to the old asphalt drying drum (16) for extracting exhaust gas, the exhaust gas extraction unit (23) comprising i. a housing (24), ii. a return line (26) connected to the housing (24), which is connected to the cold gas supply opening (29) of the hot gas generator (27) for returning exhaust gas, iii.a blower (28) arranged along the return line (26), iv. an exhaust air line (25) connected to the housing (24), which can be connected to a filter system (12), d. a control unit (33) which is designed to supply old asphalt granulate with a variably definable target temperature to the. Old asphalt discharge opening (19), wherein the control unit (33) is in signal connection with the old asphalt drying drum (16), with the hot gas generator (27) and with the exhaust gas extraction unit (23).

2. Retrofit system according to claim 1, characterized by a material feed unit (34) for automatically conveying old asphalt granulate to the old asphalt feed opening (18).

3. Retrofit system according to claim 2, characterized in that the material feed unit (34) has an elevator (35) which opens into the old asphalt feed opening (18).

4. Retrofit system according to claim 2 or 3, characterized in that the material feed unit (34) has a dosing element for the variable quantity addition of the old asphalt granulate into the old asphalt drying drum (16).

5. Retrofit system according to one of claims 2 to 4, characterized in that the material feed unit (34) is in signal connection with the control unit (33).

6. Retrofit system according to one of the preceding claims, characterized by a material discharge unit (36), in particular a chute, connected to the old asphalt discharge opening (19), wherein the material discharge unit (36) is connectable in particular to a mixing unit (9).

7. Retrofit system according to one of the preceding claims, characterized in that a filter unit is connected to the exhaust air line (25).

8. Plant for producing asphalt, comprising a. a white mineral drying drum (2) with a white mineral feed opening (4) and a white mineral discharge opening (6), b. a white mineral heat source (8) arranged on the white mineral drying drum (2), c. a mixing unit (9) connected to the white mineral discharge opening (6) for mixing the heated white mineral with at least one other material, d. a filter system (12) connected to the white mineral drying drum (2), e. a plant control system (14) for controlling asphalt production, f. a retrofit system (15) according to one of the preceding claims, wherein the control unit (33) is designed separately from the plant control system (14).

9. Plant according to claim 8, characterized by an asphalt dispensing unit (10) connected to the mixing unit (9) for dispensing the asphalt.

10. Plant according to claim 8 or 9, characterized by a storage container (11) connected to the asphalt delivery unit (10) for storing the asphalt.

11. System according to one of the preceding claims, characterized in that the exhaust air line (25) is connected to the filter system (12).

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