DE3907248C2 - Tray dryer for bulk goods, especially asphalt granulate - Google Patents

Description

The invention relates to a trough dryer for bulk goods, in particular asphalt granulate, with a tubular, with Inlet and outlet for the well-equipped body, in which a rotating mixing conveyor with parallel to Longitudinal axis of the trough body lying on the drive shaft is ordered and where the heating above the drive shaft aggregates for the material to be mixed and dried are seen.

A trough dryer of this type has become known in the reuse of asphalt for preheating of asphalt granulate DE-Z: building materials, recycling and landfill technology 3/88 p 22-25. In this known dryer ner, the free-flowing asphalt granulate is constantly circulated by a transport screw and at the same time conveyed to the trough outlet, the material being heated by infrared heaters located immediately above the transport screw. In addition to this infrared heating, heating with thermal oil is provided from below the screw conveyor. With this known trough dryer, however, the asphalt granulate could not be heated to mixing and processing temperatures; this tray dryer also has a comparatively low efficiency.

The invention is based on this prior art based on the task of a trough dryer for bulk goods, especially for asphalt granulate to be reprocessed create, on the one hand, the material to be dried intensively mixed and at the same time heated so gently, that especially when heating asphalt granulate there are no harmful emissions and that Well not changed in its molecular composition becomes. Accordingly, a trough dryer should be created be determined by the type of heating and the degree of Reactivation of the binder of reusable Asphalt granulate producing a high quality allows valuable mixed goods.

According to the invention, this object is a trough dryer of the generic type by the features of Claim 1 solved. More essential Features of the invention and further developments of the same are contained in the subclaims.

With the invention, a tray dryer is created that by means of microwaves that is constantly in circulation Well intense, yet gentle on one for the further processing desired temperature heated, in particular especially when using this tray dryer for the Er asphalt granulate is heated so gently, that the bitumen in the asphalt granulate is not be is damaged and harmful emissions ver are avoided and the heated asphalt granulate on mixed  and processing temperature immediately after this on heating a further processing, for example in a Compulsory mixer, can be supplied, in which the so reactivated construction asphalt the required Additives are added. The troughs according to the invention dryer is also characterized by a simple structure, ins special with regard to the arrangement of the microwave transmitter device and through an optimally effective coupling the microwaves into the actual body of the well, in which the material to be dried is intensive and yet gentle is constantly circulated. The tray dryer is also in constructively simple and full with simple means constantly shielded against the escape of microwaves.

In the drawings, an embodiment of the inventions inventive tray dryer shown schematically. It demonstrate

Fig. 1 is a longitudinal cross section through the tray dryer;

FIG. 2 shows a cross section perpendicular to the longitudinal axis of the bowl dryer with several domes according to FIG. 1;

Fig. 3 is a top view of the trough of the trough dryer in such a double dome according to Figure 2 with a view from above of the coupling window of the UHF boxes.

Fig. 4 is a tray dryer according to the basic union structure of FIGS . 1 to 3, but with a microwave-permeable drum for receiving the goods to be dried.

The trough dryer provided for drying bulk material, in particular asphalt granulate obtained from removed asphalt, has a tubular trough body 1 which has an inlet 2 for the material to be dried and an outlet 2 'for the dried material. In the trough body 1 there is a slowly rotating mixing and conveying tool 3 with a drive shaft 4 , which is also referred to as a mixer shaft and on which the mixer arranged, which have mixing blades 5 projecting from the mixer shaft 4 . The mixing blades 5 preferably have arms 6 which sit radially on the shaft 4 and which carry mixer fingers 7 at their free ends. The mixer fingers 7 and / or the mixer arms 6 can consist of highly wear-resistant metal or ceramic and are preferably detachable, for example by screw or plug connections, so that they can be replaced when worn. In the execution example, the mixer shaft 4 is mounted centrally in the tubular body 1 ; but it can also be arranged eccentrically, preferably below the axis of the trough body. The shaft 4 is driven by the schematically represented drive 4 A.

In the embodiment of FIGS . 1 and 2, a shaft-like dome 8 is arranged in the upper region of the tubular body 1 , on which UHF boxes 26 are mounted. Above these UHF boxes 26 are arranged in the longitudinal direction of the dryer one behind the other microwave send devices 9 (magnetrons, klystrons), each magnetron being assigned a waveguide 10 . The waveguides 10 are connected via the UHF boxes 26 with the dome 8 or in the arrangement of a double dome 8 a, 8 b via Mikrowelleneinkoppelfenster 11 flow-connected such that the 9 outgoing microwave from the magnetrons on the waveguide 10, coupling window 11 and the UHF -Boxes 26 can enter the dome 8 or the two dome sections 8 a, 8 b without loss. Between the UHF boxes 26 and the dome 8 or the dome parts 8 a, 8 b in a double dome, a dielectric end, for example in the form of at least one insulating material plate 12 , which can be made of glass or ceramic, is provided. Several such insulating material plates can be provided; the one or more of these plates are thus located in the area of the opening cross-section from the dome 8 to the upper part of the trough body 1 . The micro waves can enter the trough body unhindered. The dome 8 or, in the case of a plurality of domes, such as a double dome design, the dome sections 8 a and 8 b are advantageously welded to the trough body, while the UHF boxes 26 are arranged on the dome 8 and on the domes 8 a, 8 b in a detachable manner ,

In order to prevent microwaves from escaping from the trough body to the outside, in particular via the product inlet openings 2 or product outlet openings 2 ', the product inlet 2 and the product outlet 2 ' are honeycomb-shaped. This can be done preferably in that above or below the Guteinschlußquerschnitte in the actual trough body 1 several parallel to each other, cross-sectional square or rectangular, on the high frequency waves matched honeycomb 13 are formed. Corresponding honeycombs 14 are located at the outlet 2 'of the dried good material. As can be seen from FIG. 2, the honeycombs 13 are provided, in particular for the entry of material, also in the extension of the actual inlet 2 , namely within the upper part of the trough body 1 . In the embodiment shown in FIGS . 1 and 2 are above the dome 8 seated on the trough body 1 , which is composed of the two domes 8 a, 8 b (see FIG. 2), along its length, that is to say in the longitudinal direction Mul seen the body, several microwaves 9 arranged one behind the other. These transmission devices 9 , magnetrons 9 , are each assigned the waveguides 10 mentioned. This waveguide 10 and the magnetrons 9 can be seen in the direction transverse, preferably perpendicular, to the longitudinal axis of the trough body, the cross section of the dome or that of a double dome and / or that of the trough body since Lich ( Fig. 2).

A simple design results if the magnetrons 9 are placed on the waveguide 10 and the associated coupling-in windows 11 together with UHF boxes 26 are symmetrical to the vertical right central plane of the trough body (cf. FIGS . 1 and 3). The microwaves generated by the magnetrons 9 can thus penetrate into the interior of the hollow body in a short way and without loss of energy via the coupling window 11 , the UHF boxes 26 and the interior of the dome 8 or the double domes 8 a, 8 b and there Apply circulating material and heat. The arrangement is advantageously chosen such that the waveguides 10 are coupled in with different field directions in order to obtain maximum energy utilization, as is shown schematically in FIG. 3.

From Fig. 1 it can be seen that in the illustrated embodiment in the longitudinal direction of the trough body 1 seen several consecutive magnetrons 9 are seen before, so that over the length of the dome 8 or the dome parts 8 a, 8 b in a double dome a whole series of consecutive Magnetrons 9 with their waveguides 10 and coupling windows 11 are provided and thus the dome or the adjacent doma 8 a, 8 b in a double dome over the entire length and thus also the hollow body and the material to be dried in it, preferably different from microwaves Field direction are applied. Figs. 2 and 3 show the arrangement of the standing wave guide 10 with windows 11 corresponding to Fig. 2 from the top at a Doppeldom with the domes 8 a and 8 b which are parallel to each other. The arrows drawn in FIG. 3 into the waveguide cross sections indicate the direction of the field strength on each of the individual waveguides 10 . Ten waveguides are provided in each row, the individual rows lying next to one another and the waveguides themselves being staggered. A total of forty magnetrons 9 with associated waveguides 10 are thus seen in the exemplary embodiment in FIG. 3. The arrows show that the field strength direction in the adjacent hollow conductors 10 and the UHF boxes 26 is rotated alternately by 90 °.

In conjunction with the one or more insulating plates 12 and in the area of the inlet 2 and outlet 2 'arranged honeycombs 13 and 14 , maximum utilization of the microwave energy is achieved, since neither from the waveguides nor from the actual body of the microwave radiation can escape to the outside and the entire transmission energy is available for drying the constantly circulating good. The trough body can, for example, be made of 5 to 10 mm thick VA steel. It can also be provided that the trough body is double-walled, such that an intermediate space 17 A is formed between the wall of the trough body 1 and an outer wall 16 lying at a distance from this wall, which is caused by a flowing external heat, for example hot air or hot gases, is flowed through and thereby additionally heats the space 17 of the trough body 1 . It may be expedient to provide the outer wall 16 with an insulating material 16 'in order to avoid heat losses.

In order to prevent harmful accumulations of escaping gases or chemical substances from occurring during the heating of the material to be dried, in particular when heating asphalt granules, in particular to prevent plasma formation, the interior of the invention is, according to a further feature of the invention Trough body 1 be ventilated. For this purpose, air inlet and outlet openings 17 , 18 are preferably seen on the end faces of the body (see FIG. 1) and in the upper region of the body. In the region of the end faces and in the upper region of the trough body, viewing windows 19 are also formed, which are also covered by a shielding grid, for example a perforated plate 20 , for protection against microwave leakage. In the tray dryer according to the invention shown as an example, the actual tray body 1 is provided with a substructure, for example in the form of two supports 21 , 22 , on which the dryer rests. The necessary power supplies for the transmission devices can be accommodated in the area of this substructure 21 , 22 . In Fig. 2, these power supplies are designated with Ne 1-20 and Ne 21-40 . They are carried by a suitable frame 24 .

In the event of unfavorable structural conditions, the network parts can also be accommodated in control cabinets (not shown) which are separate from the tray dryer. It is expedient to attach the necessary high-voltage heating transformers of the magnetrons 9 preferably directly to the associated waveguides in order to form heating transformers and magnetrons together with the waveguide as compactly as possible.

To cool the magnetrons and / or heating transformers, it may be expedient to provide appropriate air ducts with forced cooling air guidance and to supply the heated air via the air inlet openings 17 , 18 to the interior of the mixing body, in order to improve the thermal efficiency of the dryer.

The tray dryer described can also be used for vacuum drying; in this case, the honeycomb channels 13 , 14 are to be provided with a vacuum lock known per se and the coupling-in window 11 is to be designed to be vacuum-tight in a likewise known manner.

The UHF boxes 26 can be air-cooled if necessary, for example by 26 air inlet and air outlet openings 25 are seen in front of two opposite longitudinal sides of these boxes, so that an intensive cross-flushing of the UHF boxes 26 by means of air and thus sufficient cooling is effected.

As can be seen from the schematic representation in FIG. 2, each waveguide 10 is assigned an adapter 27 , preferably in the form of an adjustable blade, which serves to achieve a maximum ultra-high frequency transformation in the trough body 1 .

In the also schematically illustrated alternative embodiment of FIG. 4, the basic structure of the tray dryer according to the invention corresponding to FIGS. 1 to 3 maintained. However, a drum is provided as the mixing conveyor tool, which, driven by the shaft 4 , rotates within the drum-shaped trough 1 . The material to be dried is in this drum; the drum runs in the direction of the arrows and has an inclination in the direction of its longitudinal axis, that is, in the direction of the axis of the shaft 4 , from the material inlet to the material outlet, so that the material to be dried contained therein is dried from the material inlet 13 to during the rotation of the drum Good outlet 14 located at the other end of the drum is conveyed. The drum 28 provided in the trough body is designed in such a way that it allows the microwaves that heat the material to pass through unhindered. As a result of the rotation of the drum and the associated intensive mixing of the goods, a particularly effective exposure and heating of the goods by the microwaves is therefore achieved. This version is also suitable for vacuum drying.

The embodiment shown in the drawings (cf. in particular Fig. 3) is particularly intended for drying asphalt granulate. Since this drying requires a great deal of energy, a maximum of magnetrons 9 , waveguides 10 and coupling windows 11 are provided in a very close proximity to one another in a relatively small area, their field direction, as indicated by the arrows in FIG. 3, in each case rotated by 90 ° is. As a result, the required high performance for an optimal heating of the material to be dried is achieved in a relatively small space. The standing waveguides are expediently designed as rectangular waveguides with an H ₁₀ module and a VSWR (voltage standing wave refluction) adaptation. With the trough dryer according to the invention with a half-open trough at the top and the dome or domes arranged in this area, on which in turn the UHF windows and waveguides with the magnetrons are arranged, apart from a good distribution of the microwaves, above all it is sufficient, that the coupling window are wear-free, because between the actual drying room, in which the material to be dried is circulated and in which high temperatures prevail, and the high-frequency part there is sufficient separation so that premature wear in the high-frequency part due to excessive heat is not too high fear. In addition, the field strength direction, which is rotated through 90 °, ensures that the mutual influence is reduced. As a result of the wear-free arrangement of the UHF windows, a trough dryer has been created for robust, permanent operation.

Claims (25)

1. Dump dryer for bulk goods, in particular asphalt granulate, with a tubular trough body provided with an inlet and outlet for the goods, in which a rotating mixing-conveying tool with a drive shaft lying parallel to the longitudinal axis of the trough body and above this drive shaft heating units are provided, characterized by at least a on the trough body ( 1 ), extending approximately over its length, dome ( 8 ) with in the longitudinal direction one behind the other arranged microwave transmission devices ( 9 ) (magnetrons, klystrons) and associated with these magnetrons, the microwave-directing waveguides ( 10 ) with coupling windows ( 11 ) for coupling the microwaves into the dome ( 8 ) and a dielectric closure ( 12 ) covering the opening cross section to the dome ( 8 ) and trough body ( 1 ). 2. Tray dryer according to claim 1, characterized in that a plurality of domes ( 8 a, 8 b) with a plurality of them assigned, one behind the other transmitting devices ( 9 ) and waveguides ( 10 ) are provided, the domes being arranged parallel to each other. 3. tray dryer according to claim 1 or 2, characterized in that each transmitting device ( 9 ) consists of two transverse, preferably perpendicular to the longitudinal axis of the trough body ( 1 ) lying magnetrons and their associated waveguides ( 10 ). 4. Tray dryer according to one of claims 1 to 3, characterized in that the paired magnetrons (9, Fig. 1) and the waveguides assigned to them ( 10 ) including a coupling window ( 11 ) to the ultra-high frequency (UHF) boxes ( 26 ) and the dome ( 8 ) or a double dome consisting of two parallel sections ( 8 a, 8 b) are arranged symmetrically to the vertical central plane of the trough body ( 1 ). 5. tray dryer according to one of claims 1 to 4, characterized in that, seen in cross section perpendicular to the longitudinal axis of the trough body ( 1 ), each Weil a dome ( 8 ) assigned two magnetrons ( 9 ) with waveguides ( 10 ) the cross section of Domes tower above on both sides. 6. Tray dryer according to one of claims 1 to 5, characterized in that the magnetrons ( 9 ) on the waveguide ( 10 ) are placed. 7. Tray dryer according to one of claims 1 to 6, characterized in that, seen in vertical cross section, the coupling window ( 11 ) of the associated waveguide ( 10 ) towards the dome ( 8 ) symmetrically to one another, preferably in the middle of the dome ( 8 ), are arranged. 8. tray dryer according to one of claims 1 to 7, characterized in that the dielectric closure ( 12 ) between UHF boxes ( 26 ) and dome ( 8 ) by at least one dielectric plate ( 12 ), for example an insulating plate, preferably made of glass or ceramic. 9. Tray dryer according to one of claims 1 to 8, characterized in that at least one UHF box ( 26 ) is detachably attached to the dome ( 8 ) or to the double dome ( 8 a, 8 b), for example by screw connection, and the Dom (8) or the Doppeldom (8 a, 8 b) is welded to the Mul denkörper (1). 10. tray dryer according to one of claims 1 to 9, in order to cool the UHF-boxes (26) in the dome (8) or in Doppeldom (8 a, 8 b) air inlet openings (25) and associated with these outlet openings (25) provided , 11. Tray dryer according to one of claims 1 to 10, characterized in that the inlet openings ( 2 ) for the material to be dried and the outlet openings ( 2 ') for the dried material for the purpose of shielding against microwave leakage by honeycombs ( 13 and 14) lying parallel to one another ) are formed. 12. Tray dryer according to one of claims 1 to 11, characterized in that the waveguide ( 10 ) are coupled with different field directions of the microwaves, such that the trough body in the Hori zontal section is fully acted upon by microwaves of both field directions. 13. Tray dryer according to claim 1, characterized in that the mixing conveyor ( 3 ) consists of a mixer shaft ( 4 ) with projecting mixing blades ( 5 ). 14. Tray dryer according to claim 13, characterized in that the mixing blades ( 5 ) have arms ( 6 ) with mixing fingers ( 7 ) located at their free ends. 15. Tray dryer according to claim 13 or 14, characterized in that the preferably made of metal and / or ceramic mixer fingers ( 7 ) and / or mixer arms ( 6 ) are designed to be replaceable. 16. Tray dryer according to claim 1, characterized in that the mixer shaft ( 4 ) is arranged ex-centrically, preferably below the axis of the Mul denkörpers ( 1 ). 17. Tray dryer according to one of claims 1 to 16, characterized in that above the mixer shaft ( 4 ) in the input and output area of the trough body, preferably on its end faces, air inlet and air outlet openings ( 17 , 18 ) are provided for ventilation of the trough body interior , 18. Tray dryer according to claim 1, characterized in that the trough body ( 1 ) for the purpose of forming a heating jacket ( 17 A) is provided with a double wall ( 16 ). 19. Tray dryer according to claim 1 or 2, characterized in that the power supplies (Ne 1-20 ; Ne 21-40 ) are provided for the associated magnetrons in the lower part of the tray dryer. 20. Tray dryer according to claim 1 or 2, characterized in that the power supplies (Ne 1-20 ; Ne 21-40 ) are provided in separate cabinets from the tray dryer and the heating transformers for the magnetrons are arranged on waveguides. 21. Tumble dryer according to one of claims 1 or 2, characterized in that on the trough body ( 1 ) viewing window ( 19 ) are provided, which are provided with protection against microwave leakage, for example a perforated aperture ( 20 ). 22 tray dryer according to one of claims 1 to 21, characterized in that in the Mul dent dryer training for vacuum drying the honeycomb channels ( 13 , 14 ) in the Gutein and Gutaus each provided with a vacuum lock and the coupling window ( 11 ) also in known per se Are vacuum-proof formed. 23 tray dryer according to claim 1 to 22, characterized in that in the region of the waveguide ( 10 ), an adapter ( 27 ), preferably in the form of an adjustable wing or the like. For maximum UHF transformation in the trough body ( 1 ) is provided. 24. Trough dryer according to one of claims 1 to 12 and 17 to 23, characterized in that as a rotating mixing and conveying tool, the microwave-permitting drum ( 28 ), for example made of ceramic, glass or the like, as a receptacle for the material to be dried is provided, which is driven by the drive shaft ( 4 ) rotating. 25. Tray dryer according to claim 24, characterized in that the drum ( 28 ) has a box-shaped cross-section and is provided with a material inlet ( 2 ) at one end and a material outlet ( 2 ') at the other end and towards the material outlet towards the horizontal is inclined.