DK2554746T3

DK2554746T3 - A process and plant for the production of asphalt

Info

Publication number: DK2554746T3
Application number: DK12174279T
Authority: DK
Inventors: Frank Wagner; Hans Adam
Original assignee: Benninghoven Gmbh & Co Kg Muelheim
Priority date: 2011-08-05
Filing date: 2012-06-29
Publication date: 2014-03-10
Also published as: EP2554746B1; EP2554746A1; DE102011080537A1

Description

The invention relates to a method and to an installation for the production of asphalt.

When producing asphalt, it is possible to use granules recovered from recycled old asphalt. Granules of this type are also referred to old asphalt granules or recycled granules. It is however not possible to add an unlimited amount of old asphalt granules when producing asphalt. The admixture of an excessive amount of old asphalt granules impairs both the quality of the produced asphalt mass and the process safety when the method is carried out. A method and a device for the production of old asphalt concrete are known fro DE 30 34 341 C2 according to which the moisture content of additives is determined, a mixture of additives and binders is introduced into a mixing chamber where it is indirectly heated and mixed. In order to ensure that the quality of the asphalt mass thus produced is not impaired, the moisture content of the additives is reduced as soon as a critical maximum permissible amount of additives is reached. An installation for the cyclical production of asphalt is known from US 5,432,606. Methods of this type are complex.

It is an object of the present invention to improve a method for the production of asphalt in such a way as to simplify the admixture of old asphalt granules while ensuring that in particular the process safety of the production method and the quality of the produced asphalt are not impaired.

This object is achieved by the features of claim 1 in a manner that is not obvious to a person skilled in the art. A moisture content of provided old asphalt granules is measured by means of at least one moisture sensor, and then a permissible supply quantity for the old asphalt granules is determined as a function of the measured moisture content of the old asphalt granules. The moisture content of the old asphalt granules may for instance be influenced by the weather since the old asphalt granules are usually stored outside. A change of the moisture content of the old asphalt granules may for instance be due to the outside temperature and/or precipitation. The moisture content may also vary depending on the place of origin of the old asphalt granules. In this context, the term “moisture content” refers to the relative mass fraction of water in relation to the total mass of old asphalt granules. It is for instance conceivable as well for this value to be based on the relative moisture contained in the old asphalt granules. The permissible supply quantity of the old asphalt granules thus determined is then supplied to a mixing device where it is mixed with raw asphalt granules. This ensures that a supplied quantity of old asphalt granules observers, in other words does not exceed, a critical permissible upper moisture limit. This prevents water vapour, which is produced substantially explosively when supplying the old asphalt granules to the mixing device, from exceeding a permissible maximum quantity. The permissible maximum quantity of the old asphalt granules is in particular influenced by a maximum permissible temperature of white minerals, an instantaneous temperature of the product to be mixed that is present in the mixing device, the moisture content of the old asphalt granules and an amount of water vapour resulting from the moisture content of the asphalt granules which develops when the moist old asphalt granules are supplied to the mixing device. The old asphalt granules are supplied to the heated mixing device in a controlled manner, in other words in a controlled amount. This ensures that the water vapour which develops does not affect the production method. A reduced amount of water vapour develops in relation to a period of time. The pressure increase resulting from the development of water vapour in the mixing device is uncritical for the weighing devices connected to the mixing device for various components to be admixed such as bitumen, fillers or a rock mixture required for the production of asphalt, which is referred to as raw asphalt granules in the following, in the form of mineral rocks. Furthermore, pressure variations in a drying drum connected to the mixing device can be prevented as well, with the result that a combustion process carried out there is not affected so that the emission values remain stable. Furthermore, the method according to the invention allows the process safety to be improved and in particular a hazard potential to be reduced since the reduced amount of water vapour that develops precludes a potential explosion hazard of a mixing device and a dust exhausting device connected thereto. The use of old asphalt granules for the production of asphalt is hazard-free while in particular allowing the amount of raw asphalt granules to be reduced. Compared to known methods for the production of asphalt, the amount of old asphalt granules can be increased. This in particular allows both the costs and the C02 emissions to be reduced when producing asphalt. A method according to which it is provided to measure the supply quantity of the old asphalt granules, which are conveyed by a conveyor device, by means of a weighing device allows various influencing measures to be taken for the method to be performed in a controlled and in particular regulated manner. In particular, it is conceivable to monitor and adjust a mass flow rate, in other words the mass of old asphalt granules supplied per unit time, in such a way that the permissible supply quantity for old asphalt granules is observed. In addition or as an alternative, it is conceivable as well to monitor and correspondingly adjust a feed rate, in other words a supply rate, for supplying the old asphalt granules from the storage container to the mixing device. The method allows for a multi-variable admixture of old asphalt granules. A method according to claim 2 ensures that a sufficient amount of old asphalt granules is available at any point in time during production. It is possible to supply a controlled mass of old asphalt granules to a storage container. In particular it is conceivable to monitor a fill level for old asphalt granules in the storage container by means of at least one fill level sensor, and in particular to adjust an amount of old asphalt granules to be supplied to the storage container according to a current fill level. A method according to claim 3 ensures a continually updated measurement of the moisture content of the old asphalt granules. This is in particular advantageous if a high mass throughput of old asphalt granules is supplied to the storage container, which may lead to a varying moisture content of the old asphalt granules. A method according to claim 4 allows the old asphalt granules to be supplied to the mixing device in an unheated state, in other words without performing a previously required heating process, in particular at ambient temperature. As a re suit, the method becomes cheaper and easier. Moreover, C02 emissions are reduced when the preheating step is omitted. Furthermore, the old asphalt granules keep an excellent binding power since the bitumen contained in the old asphalt granules is not affected and is in particular not burned. A method according to claim 5 allows a supply rate to be changed as a function of the moisture content of the old asphalt granules. This ensures that the old asphalt granules are supplied to the mixing device in such a way as to prevent damages thereto. In particular, this allows a rapid vapour development of the water stored in the moist old asphalt granules to be prevented. A method according to claim 7 allows an up-to-date determination of the mass of the old asphalt granules supplied to the mixing device by means of the conveyor device. It is in particular conceivable to reduce the mass flow from the storage container to the conveyor device, in other words the supply rate, as a function of the measured mass of old asphalt granules. The production of asphalt is performable in an entirely automated and controlled manner. It is in particular possible to ensure a constantly high quality level of the quality of the produced asphalt.

Another object of the present invention is to improve an installation for the production of asphalt in such a way as to simplify the admixture of old asphalt granules while ensuring that in particular the process safety of the production method and the quality of the produced asphalt are not impaired.

This object is achieved by an installation having the features set out in claim 8 in a manner that is not obvious to a person skilled in the art. The installation for the production of asphalt has a supply unit which enables a permissible supply quantity of old asphalt granules to be supplied from a storage container to a mixing device. In doing so, the permissible supply quantity is determined as a function of a measured moisture content of the old asphalt granules stored in the storage container. The advantages resulting therefrom are identical to those of the inventive method according to claim 1.

The moisture content of the old asphalt granules is determined by means of at least one moisture sensor in the storage container. The storage container may in particular be a buffer silo.

An installation in which the supply unit is provided with a metering device for metering a mass flow of old asphalt granules discharged from the storage container allows for a metered supply of old asphalt granules from the storage container. The mass flow of old asphalt granules discharged from the storage container may for example be an adjustable feeder, a conveyor screw drivable at different speeds, a metering belt or a rotary feeder. In particular, a rough amount of the old asphalt granules is initially supplied to the conveyor belt at a high mass flow rate, wherein the supply unit is then switched to fine metering for supplying the old asphalt granules to the conveyor belt at a reduced mass flow rate. The conveyor belt is in particular loaded continuously during rough metering, and the mass of the old asphalt granules on the conveyor belt is measured continuously by means of the weighing device. An installation in which the conveyor device is configured as a conveyor belt, which has a weighing device for measuring the supply quantity of the conveyed old asphalt granules enables the mass of the old asphalt granules arranged on the conveyor device to be measured and in particular monitored.

An installation according to claim 9 enables the point in time for supplying the supply quantity and the supply rate of the old asphalt granules into the mixing device to be varied by changing a feed rate of a conveyor device. The conveyor device is configured as a conveyor belt which can be operated in particular at a very low feed rate such as less than 1 m/s, in particular less than 0.1 m/s and in particular less than 0.01 m/s.

An installation according to claim 11 ensures a short overall length of the conveyor belt since the old asphalt granules transported on the conveyor belt are arrangeable on top of each other by means of lateral, in particular wear-proof boundary walls. In addition to the lateral boundary walls, it is in particular conceivable to provide an upper boundary cover which interconnects the two lateral boundary walls so that the conveyor belt is substantially provided with a casing. This ensures that the old asphalt granules transported on the conveyor belt are protected from external influences. This in particular ensures that the moisture content of the old asphalt granule on the conveyor belt does not deviate from the measured moisture content of the old asphalt granules in the storage container. Negative effects on the subsequent mixing process due to a different moisture content are thus prevented. The quality of the produced asphalt is improved.

An installation according to claim 12 guarantees a sufficient amount of old asphalt granules in the storage container.

An installation according to claim 13 allows for an automated and controlled production. It is in particular conceivable to reduce personnel expenses and costs when the installation is operated.

An installation according to claim 14 allows various devices of the installation to be operated via a control device, depending on the degree of automation the installation is operated with. This in particular allows an installation to be provided that is adapted to the individual needs and knowledge of different customers.

Additional features and details of the invention will be apparent from the description of an embodiment with reference to the drawing in which

Fig. 1 shows a schematic representation of an installation according to the invention.

An installation 1 for the production of asphalt shown in Fig. 1 comprises three storage containers 2 each of which contains old asphalt granules 3. Also referred to as dosers, the three storage containers 2 may be loaded with old asphalt granules 3 independently of each other. This may for instance be carried out directly by means of a lorry. It is conceivable to provide more or less than three but at least one storage container 2. The old asphalt granules 3 are discharged by means of a conveyor system 4. According to the shown exemplary embodiment, the conveyor system is configured as a discharge conveyor 4. The discharge conveyor 4 is driven by a discharge conveyor motor 5 and allows the old asphalt granules 3 to be transported to an elevator 6 which transports the old asphalt granules 3 to a storage container 7 in the form of a buffer silo.

In the buffer silo 7, the old asphalt granules 3 are stored, in other words buffered, wherein a current fill level h of the buffer silo 7 is monitored by means of at least one fill level sensor 8. The fill level sensor 8 is configured as a rotating paddle detector in the buffer silo 7. For example, it is conceivable as well for the fill level sensor 8 inside the buffer silo 7 to detect the fill level in a capacitive manner. Other embodiments of fill level sensors 8 are conceivable as well. The current fill level h is transmitted by the fill level sensor 8 to a control device 9 which is in signal communication with the fill level sensor 8 and the discharge conveyor motor 5. As soon as the level falls below a minimum threshold value of the fill level hmin and is detected by the fill level sensor, a signal is transmitted to the control device 9 which transmits a corresponding signal to the discharge conveyor motor 5. The feed rate of the discharge conveyor 4 is increased, with the result that a larger amount of old asphalt granules 3 is transported to the buffer silo 7 via the elevator 6 per unit time. Correspondingly, the fill level sensor 8 emits a signal as soon as an upper maximum threshold value hmax is reached, causing the control device 9 to transmit a signal to the discharge conveyor motor 5 so that the feed rate of the discharge conveyor 4 is reduced. The threshold values hmin, hmax are set in such a way as to prevent a complete discharge or overflow of the buffer silo 7.

Furthermore, the buffer silo 7 is provided with a moisture sensor 10 which detects the moisture content of the old asphalt granules 3 in the buffer silo 7. The moisture sensor 10 is in signal communication with the control device 9. A lower end of the buffer silo 7 is provided with a metering device 11 for metering a mass flow of old asphalt granules 3 discharged from the buffer silo 7. In the shown exemplary embodiment, the metering device is configured as a feeder in a discharge opening. The feeder is displaceable in the discharge opening in such a way that the cross-sectional surface surrounded by the discharge opening is changeable by displacing the feeder 11. This allows the amount discharged from the buffer silo 7 per unit time, in other words the mass flow rate, of the old asphalt granules 3 to be influenced. The feeder is in signal communication with the control device 9. The metering device 11 may for instance also be configured as a conveyor screw, a metering belt or a rotary feeder. The metering device 11 is variably adjustable and in particular allows a rough metering to be performed at a high mass flow rate of old asphalt granules 3 of more than 50 t/h, in particular of more than 500 t/h, and in particular of more than 1000 t/h. Furthermore, the metering device 11 can be set to fine metering so that only a small mass flow of old asphalt granules 3 is discharged from the buffer silo 7. When set to fine metering, the mass flow rate amounts to no more than 100 kg/s, in particular to no more than 10 kg/s, and in particular to no more than 1 kg/s.

When set to rough metering, the required quantity of old asphalt granules 3 can be provided in a short time, wherein in particular no more than 80% of the required quantity, in particular no more than 90% of the required quantity and in particular no more than 95% of the required quantity are supplied by rough metering. A required remaining quantity is provided by fine metering, with the result that the required quantity is provided at a high level of accuracy. In particular, deviations of the required quantity of less than 5%, in particular of less than 2% and in particular of less than 1 % are achievable.

If the metering device 11 has an afterrunning, in other words old asphalt granules 3 are discharged from the buffer silo 7 although the metering device 11 is already completely closed, the amount of old asphalt granules 3 discharged by afterrunning can be taken into account during fine metering. The deviation of a predetermined quantity of old asphalt granules 3 discharged from the buffer silo 7 is reduced.

Via the metering device 11, the old asphalt granules 3 are transported to a conveyor device in the form of a conveyor belt 12. The conveyor belt 12 has a con veyor belt motor 13 which enables the old asphalt granules 3 arranged on the conveyor belt 12 to be transported from the buffer silo 7 to a mixing device 15 via a slide 14. The conveyor belt motor 13 is in signal communication with the control device 9. Via the slide 14, the old asphalt granules 3 are able to reach the mixing device 15 automatically due to gravity. The mixing device 15 is configured in the form of a twin-shaft compulsory mixer which is drivable for rotation about its central longitudinal axis 16. Other designs of the mixing device 15 are conceivable as well. Moreover, rock material referred to as raw asphalt granules forming the basic mass for the production of the asphalt can be supplied via a separate supply container 17 of the mixing device 15. Furthermore, it is conceivable to add various additives such as fillers, bitumen and/or other minerals to the mixing device 15, depending on the mixture of an asphalt product to be produced.

An upper side of the conveyor belt 12 is provided with lateral boundary walls 18 which are made of a particularly wear-proof material. This allows larger amounts of old asphalt granules 3 to be arranged on the conveyor belt 12 without the risk of falling over the sides of the conveyor belt 12 and getting lost. This is in particular advantageous if the conveyor belt 12 is driven by the conveyor belt motor 13 at a low feed rate v of for instance less than 1 m/s, in particular less than 0.1 m/s, and in particular less than 0.01 m/s.

The presence of the boundary walls 18, which allow the old asphalt granules 3 to be arranged in a pile on the conveyor belt 12, enables the conveyor belt 12 to carry a larger amount of old asphalt granules 3. It is conceivable for the conveyor belt 12 to be designed with a comparatively short overall length. As a result, the space requirement for the entire installation 1 and the operating costs thereof are reduced.

The conveyor belt 12 has a weighing device which enables the old asphalt granules 3 transported on the conveyor belt 12 to be weighed with an extremely high level of precision. In the shown exemplary embodiment, the weighing device comprises two weighing cells 19. The conveyor belt 12 is placed on the weighing cells 19. Alternatively, it is conceivable for the conveyor belt 12 to be suspended from the weighing cells 19. It is conceivable as well to use only one or more than two weighing cells 19. The weighing cells 19, and therefore the weighing device, are in signal communication with the control device 9.

The following is a more detailed description of a method according to the invention for the production of asphalt by means of Fig. 1. Old asphalt granules 3 are supplied from the storage containers 2 to the buffer silo 7 via the conveyor system 4 and the elevator 6. A fill level monitoring system guarantees by means of the fill level sensor 8 that a sufficient amount of old asphalt granules 3 is available in the buffer silo 7 during production.

The moisture content of the old asphalt granules 3 provided in the buffer silo 7 is measured by means of at least one moisture sensor 10. The measured moisture content of the old asphalt granules 3 is used to determine a permissible supply quantity and a permissible supply rate for the old asphalt granules 3. The permissible supply quantity is a maximum permissible quantity of old asphalt granules 3 to be admixed which can be safely supplied to the mixing device 15 on the basis of the moisture content. Correspondingly, the permissible supply rate is a maximum permissible rate at which the old asphalt granules can be safely supplied to the mixing device 15 on the basis of its moisture content. The maximum permissible supply quantity and the maximum permissible supply rate for old asphalt granules 3 are determined as a function of the moisture content measured by the moisture sensors 10. For example, at a moisture content of 3%, the permissible supply quantity for old asphalt granules 3 amounts to 8 t/min. The higher the moisture content, the lower the permissible supply quantity and the permissible supply rate.

The determination of the permissible supply quantity and the permissible supply rate may for instance occur in an automated manner by means of threshold values for particular moisture contents of old asphalt granules 3 stored in the control device 9. To this end, the moisture sensor 10 transmits the measured moisture content to the control device 9. When the permissible supply quantity and/or the permissible supply rate are observed, it is ensured that the amount of water vapour, which develops explosively when the old asphalt granules 3 are admixed, is so small that it is uncritical both for the quality of the asphalt to be produced and for the production method to be carried out. It is in particular conceivable for the permissible supply quantity of the old asphalt granules to be a function of process parameters in the mixing device 15. Parameters of this type may for instance be the temperature of a mixed total mass available in the mixing device 15, a total moisture content in the mixing device 15 or the pressure in the mixing device 15.

By means of a supply unit 20, the supply quantity of the old asphalt granules 3 is adjustably set on the basis of a currently measured moisture content of the old asphalt granules 3 in the buffer silo 7 and is then supplied to the mixing device 15. The supply unit 20 comprises the metering device 11 and the conveyor belt 12.

The permissible supply quantity of the old asphalt granules 3 determined on the basis of the moisture content is transmitted by the control device 9 to the metering device 11. The metering device 11 is then operated to supply a rough amount of old asphalt granules 3 to the conveyor belt 12 at a high mass flow rate. During rough metering, the feeder of the metering device 11 is in a first open position so that the cross-sectional surface of the discharge opening is opened, in particular to a maximum extent. During rough metering, the conveyor belt 12 is driven at a feed rate v of 0.1 m/s and in particular of 0.01 m/s. The conveyor belt 12 is continuously loaded during rough metering, and the mass of the old asphalt granules 3 on the conveyor belt 12 is continuously measured using the weighing device. As soon as a threshold value of for instance 95% of the supply quantity is reached, the metering device 11 is switched from rough metering to fine metering. This is done by displacing the feeder of the metering device 11 to a second open position in which the discharge opening is partly closed. The cross-sectional surface, and therefore a mass flow of old asphalt granules 3 discharged on the conveyor belt 12 via said cross-sectional surface, is reduced compared to the first open position. If the metering device 11 is pro- vided with a conveyor screw or a conveyor belt, the metering rate of the conveyor screw or of the conveyor belt, respectively, is reduced when switching from rough metering to fine metering. A possible afterrunning of the metering device 11 is taken into account by the fact that the metering device 11 is closed for instance as soon as a threshold value of 99%, in particular of 99.5% and in particular 99.9% of the supply quantity is reached. The respective threshold value is a function of the afterrunning of the respective metering device 11 and is stored in the control device 9. The combination of rough metering and fine metering ensures fast and precise metering, especially as far as the supply quantity is concerned.

The supply quantity of the old asphalt granules 3, which is precisely weighed on the conveyor belt 12, can be supplied to the mixing device 15 at any desired point in time. The conveyor belt 12 is operated and started by means of the control device 9 depending on process parameters in the mixing device 15 and/or the moisture content of the old asphalt granules 3. The control device 9 not only allows the supply time but also the supply rate of the supply quantity to be set. As a result, the installation 1 provides various ways of variably supplying old asphalt granules and other components. The installation ensures a so-called multi-variable admixture of old asphalt granules 3.

The following tables 1 to 6 contain maximum mixing capacities, given in t/h, wherein the old asphalt granules are supplied in a multi-variable manner as a function of an old asphalt granule content and of the temperature of the product to be mixed in the mixing device 15. The mixing device 15 is a 3t mixer. This means that the mixer has a maximum capacity of 3t. The temperature of the white minerals added amounts to 400°C. The temperature of the old asphalt granules 3 added amounts to 10°C. The tables 1 to 6 differ in that each of them is based on a different moisture content of the old asphalt granules 3. The moisture content according to table 1 amounts to 1%, the moisture content according to table 2 amounts to 2%, the moisture content according to table 3 amounts to 3%, the moisture content according to table 4 amounts to 4%, the moisture content according to table 5 amounts to 5%, and the moisture content according to table 6 amounts to 6%.

Table 1: Maximum mixing capacity of old asphalt granules having a moisture content of 1%

Table 2: Maximum mixing capacity of old asphalt granules having a moisture content of 2%

Table 3: Maximum mixing capacity of old asphalt granules having a moisture content of 3%

Table 4: Maximum mixing capacity of old asphalt granules having a moisture content of 4%

Table 5: Maximum mixing capacity of old asphalt granules having a moisture content of 5%

Table 6: Maximum mixing capacity of old asphalt granules having a moisture content of 6%

The tables show that a maximum mixing capacity limit of 240 t/h is reached when the temperature of the product to be mixed increases and when the content of old asphalt granules increases. When the moisture content of the old asphalt granules increases, this limit will shift in such a way that the temperatures of the product to be mixed as well as the contents of old asphalt granules 3 are reduced. If a moisture content of the old asphalt granules 3 in particular amounts to at least 4%, a conventional admixture of old asphalt granules 3 at a maximum mixing capacity of 240 t/h is no longer possible. The grey cells in tables 2 to 6 represent mixing conditions that are achievable using the installation 1 according to the invention, in other words by means of a multi-variable admixture of old asphalt granules 3. A mixing capacity of this type would not be possible using a prior art installation. Tables 1 to 6 show that the installation 1 according to the invention enables old asphalt granules to be admixed at a reduced supply rate, allowing the developing water vapour be discharged safely. As a result, the total supply quantities of old asphalt granules 3 during asphalt production can be increased.

The present device and the method allow old asphalt granules 3 to be supplied to the mixing device 15 in a controlled and in particular very precise manner. For instance, the higher the moisture content of the old asphalt granules, the slower the rate at which the old asphalt granules 3 are supplied to the mixing device 15 in which temperatures of several hundred degrees, in particular of up to 350° - 400°C, may occur. This prevents a potential vapour explosion when the old asphalt granules 3 are admixed. The old asphalt granules are heated carefully and evenly, allowing for a targeted discharge of the water vapour substantially without explosions. As a result, an increased admixture of old asphalt granules 3 is achievable.

Claims

1. Fremgangsmåde til fremstilling af asfalt, og som omfatter følgende fremgangsmådetrin: - at der klargøres et gammelasfalt-granulat (3) - at der måles et fugtindhold i det klargjorte gammelasfalt-granulat (3) ved hjælp af mindst en fugt-føler (10), - at der afhængigt af det målte fugtindhold i gammelasfalt-granulatet (3) bestemmes en tilladelig tilførselsmængde af gammelasfalt-granulat (3), - at den tilladelige tilførselsmængde af gammelasfalt-granulat (3) tilføres til en blandeindretning (15), - at det tilførte gammelasfalt-granulat (3) blandes med et råasfalt-granulat i blandeindretningen (15), og - at der under brug af en vejeindretning (19) foretages en måling af den tilladelige tilførselsmængde af gammelasfalt-granulat (3), idet sidstnævnte transporteres på en transportindretning (12) i form af et transportbånd (12), kendetegnet ved, - at der i et første trin - ved hjælp af en doseringsindretning (11) - foretages en grovdosering med en stor massestrøm af gammelasfalt-granulat (3) på transportbåndet (12), og derefter skiftes om til en findosering med en reduceret massestrøm af gammelasfalt-granulat (3) på transportbåndet (12), og - at transportbåndet (12) under grovdoseringen kontinuerligt fyldes, og at massen af gammelasfalt-granulat (3) på dette transportbånd (12) kontinuerligt måles ved hjælp af vejeindretningen (19).A process for preparing asphalt, comprising the following process steps: - preparing an old asphalt granulate (3) - measuring a moisture content of the prepared old asphalt granulate (3) by at least one moisture sensor (10). - depending on the measured moisture content of the old asphalt granulate (3), a permissible amount of old asphalt granulate (3) is determined, mixing the added old asphalt granulate (3) with a raw asphalt granulate in the mixer (15), and - using a weighing device (19), measuring the permissible amount of old asphalt granulate (3), the latter being conveyed on a conveying device (12) in the form of a conveyor belt (12), characterized in that - in a first step - by means of a dosing device (11) - a coarse dosing with a large mass flow of old asphalt granulate (3) on the conveyor belt (12), and then switched to a fine dosing stream with a reduced mass flow of old asphalt granulate (3) on the conveyor belt (12), and - during conveying the conveyor belt (12) continuously, and the mass of old asphalt granulate (3) on this conveyor belt (12) is continuously measured by the weighing device (19).

2. Fremgangsmåde ifølge krav 1, kendetegnet ved, at klargøringen af gammelasfalt-granulatet (3) foretages i en lagerbeholder (7), og at der især foretages en overvågning af fyldningsniveauet (h) i lagerbeholderen (7).Method according to claim 1, characterized in that the preparation of the old asphalt granulate (3) is carried out in a storage container (7) and in particular a monitoring of the filling level (h) is carried out in the storage container (7).

3. Fremgangsmåde ifølge et af de foregående krav, kendetegnet ved, at målingen af fugtindhold gentages, og især foretages kontinuerligt.Method according to one of the preceding claims, characterized in that the measurement of moisture content is repeated and in particular continuous.

4. Fremgangsmåde ifølge et af de foregående krav, kendetegnet ved, at gammelasfalt-granulatet (3) påfyldes blandeindretningen (15) i uopvarmet tilstand, især ved omgivelsernes temperatur.Process according to one of the preceding claims, characterized in that the old asphalt granulate (3) is charged to the mixing device (15) in the unheated state, especially at ambient temperature.

5. Fremgangsmåde ifølge et af de foregående krav, kendetegnet ved, at tilførslen af tilførselsmængden ved en justerbar tilførselshastighed foretages ved, at man transporterer gammelasfalt-granulatet (3) med en justerbar transporthastighed (v) - og dette især ved hjælp af transportindretningen (12), som er særlig drivbar på justerbar måde.Method according to one of the preceding claims, characterized in that the supply of the feed quantity at an adjustable feed rate is carried out by transporting the old asphalt granulate (3) with an adjustable transport rate (v) - and this in particular by means of the transport device (12). ), which is particularly drivable in an adjustable manner.

6. Fremgangsmåde ifølge et af de foregående krav, kendetegnet ved, at den anvendte vejeindretning omfatter mindst en vejecelle (19).Method according to one of the preceding claims, characterized in that the weighing device used comprises at least one weighing cell (19).

7. Fremgangsmåde ifølge et af de foregående krav, kendetegnet ved, at tilførslen af den tilladelige tilførselsmængde af gammelasfalt-granulat (3), især ved tilførselshastigheden, foretages styret, især reguleret.Process according to one of the preceding claims, characterized in that the supply of the permissible supply amount of old asphalt granulate (3), especially at the feed rate, is controlled, especially controlled.

8. Anlæg til fremstilling af asfalt, og som omfatter: a. en lagerbeholder (7) til gammelasfalt-granulat (3) og med mindst en fug-tighedsføler (10) til måling af et fugtindhold i nævnte granulat (3), b. en blandeindretning (15) til blanding af råasfalt-granulat med gammelasfalt-granulat (3), c. en tilførselsenhed (20) til tilføring af en tilladelig tilførselsmængde, som er bestemt i afhængighed af det målte fugtindhold i gammelasfalt-granulatet (3), fra lagerbeholderen (7) til blandeindretningen (15), hvilken tilførselsenhed (20) omfatter en transportørindretning i form af et transportbånd (12), kendetegnet ved, d. at transportbåndet (12) er forsynet med en vejeindretning (19) til måling af den tilladelige tilførselsmængde af transporteret gammelasfalt-granulat (3), og e. at tilførselsenheden (20) er forsynet med en doseringsindretning (11) til dosering af en fra lagerbeholderen (7) bortledt massestrøm af gammelasfalt-granulat (3) på en sådan måde, at der kan ske en grovdosering med en stor massestrøm af gammelasfalt-granulat (3) på transportbåndet (12) - og at der derefter kan omskiftes til findosering med en reduceret massestrøm af gammelasfalt-granulat (3) på transportbåndet (12), og dette medens transportbåndet (12) kontinuerligt fyldes, og massen af gammelasfalt-granulat (3) på transportbåndet (12) kontinuerligt afmåles ved hjælp af veje-indretningen (19).8. An asphalt manufacturing plant comprising: a. A storage container (7) for old asphalt granulate (3) and having at least one moisture sensor (10) for measuring a moisture content of said granulate (3), b. a mixer (15) for mixing crude asphalt granulate with old asphalt granulate (3), c. a feed unit (20) for supplying a permissible feed amount determined depending on the measured moisture content of the old asphalt granulate (3), from the storage container (7) to the mixing device (15), which supply unit (20) comprises a conveyor device in the form of a conveyor belt (12), characterized in that the conveyor belt (12) is provided with a weighing device (19) for measuring the permissible feed quantity of transported old asphalt granulate (3), and e. the feed unit (20) is provided with a metering device (11) for dispensing a mass flow of old asphalt granulate (3) so discharged from the storage container (7), that can happen a coarse dosing with a large mass flow of old asphalt granulate (3) on the conveyor belt (12) - and then can be switched to fine dosing with a reduced mass flow of old asphalt granulate (3) on the conveyor belt (12), and this while the conveyor belt (12 ) is continuously filled and the mass of old asphalt granulate (3) on the conveyor belt (12) is continuously measured by the weighing device (19).

9. Anlæg ifølge krav 8, kendetegnet ved, at transportbåndet (12) muliggør transport af gammelasfalt-granulatet (3) med foranderlig transportbånd-hastighed (v).An installation according to claim 8, characterized in that the conveyor belt (12) enables transport of the old asphalt granulate (3) at variable conveyor belt speed (v).

10. Anlæg ifølge krav 8 eller 9, kendetegnet ved, at vejeindretningen har mindst en vejecelle (19).System according to claim 8 or 9, characterized in that the weighing device has at least one weighing cell (19).

11. Anlæg ifølge et af kravene 8 til 10, kendetegnet ved, at transportbåndet (12) ved siderne har afgrænsende vægge (18), især ved at være anbragt i et hus.Installation according to one of Claims 8 to 10, characterized in that the conveyor belt (12) has side walls (18) at the sides, in particular by being arranged in a housing.

12. Anlæg ifølge et af kravene 8 til 11, kendetegnet ved, at det har mindst en fyldniveau-føler (8) til overvågning af fyldniveauet (h) for gammelasfalt-granulat (3) i lagerbeholderen (7).Plant according to one of claims 8 to 11, characterized in that it has at least one filling level sensor (8) for monitoring the filling level (h) of old asphalt granulate (3) in the storage container (7).

13. Anlæg ifølge et af kravene 8 til 12, kendetegnet ved, at det har mindst en styreindretning (9) til bestemmelse af den tilladelige tilførselsmængde af gammelasfalt-granulat (3).System according to one of claims 8 to 12, characterized in that it has at least one control device (9) for determining the permissible amount of feed of old asphalt granulate (3).

14. Anlæg ifølge krav 13, kendetegnet ved, at styreindretningen (9) - som tjener til styring og især regulering af tilførslen af den tilladelige tilførselsmængde af gammelasfalt-granulat (3) ved den tilladelige tilførselshastighed - står i signalforbindelse med mindst en fugtighedsføler (10), en doseringsindretning (11), en transportindretning (12), en vejeindretning og/eller en fyldniveau-føler (8).Installation according to claim 13, characterized in that the control device (9) - which serves to control and in particular control the supply of the allowable supply of old asphalt granulate (3) at the permissible feed rate - is in signal communication with at least one humidity sensor (10). ), a metering device (11), a transporting device (12), a weighing device and / or a fill level sensor (8).