EP0033911B1 - Device for capacitive high-frequency heating of fragments containing bitumen or tar - Google Patents

Description

The invention relates to a device for the capacitive high-frequency heating of asphalt or tar-containing chunk material, in particular material originating from reusable road surfaces, to a final temperature of 170 to 200 ° C.

In the interest of the scarcity of raw materials, it is of interest today to reuse the chunks of road material that arise when repairing or abandoning roads. To this end, it is already known to heat the broken pieces with hot steam or in rotary furnaces with hot gases. As a result of the poor heat transfer and the heat insulation properties, it is relatively difficult to heat large pieces, which are normally produced when they are broken down, sufficiently quickly. A previous crushing requires a high electrical energy expenditure for the mechanical crusher drives, brings about a relatively large wear on mechanical parts as well as undesired sharp-edged breaking of the fillers contained in the road surfaces, e.g. the pebble.

For the application mentioned above, capacitive heating in the high-frequency field would therefore be advantageous, since here the heating does not penetrate from the outside in, but the heat is generated uniformly in the entire material. However, the problem arises here that there must be an approximately uniform bed height in the high-frequency field, since otherwise the vertically larger parts are heated much more strongly in a vertical electrode field than the smaller parts.

Based on this fact, the object of the present invention is to design a capacitive high-frequency heating device in such a way that the material can be easily and uniformly heated to the final temperature.

This object is achieved according to the invention by a first capacitive continuous furnace in which the chunk material transported between the electrodes can be heated to plastic deformability at 80 to 100 ° C, a subsequent mechanical leveling device in which the transported material can be deformed to approximately the same layer thickness and one following capacitive continuous furnace, in which the material can be heated to the final temperature with an approximately uniform distance from the upper electrode.

In this way, uniform heating of the asphalt pavement masses can be achieved, which is an extraordinary advantage for immediate further processing.

So that the system can be brought as close as possible to the place where the material is to be reused, continuous ovens including electrical devices and also the leveling device are advantageously installed in transportable containers.

In the above context, it should be noted that capacitive continuous furnaces have long been known per se for the dielectric heating of goods of all kinds.

• Die vorliegende Erwärmungseinrichtung besteht im Prinzip aus zwei kapazitiven Hochfrequenzdurchlauföfen 1 und 3 und einer zwischengeschalteten Nivelliereinrichtung 2.

The invention is explained in more detail using an exemplary embodiment:

• The present heating device basically consists of two capacitive high-frequency continuous furnaces 1 and 3 and an intermediate leveling device 2.

The continuous furnace 1 consists, in a manner known per se, of a metallic, grounded conveyor belt 13 which serves as the lower electrode and an upper electrode 12 which is height-adjustable in the direction of the double arrow 15 and which is connected to the high-frequency generator 11, e.g. operates at a frequency of 25 MHz. The furnace 3 is constructed in the same way and also consists of a conveyor belt 33, which serves as the lower electrode, an upper electrode 32, which can be adjusted in the direction of the double arrow 35, and the high-frequency generator 31. The high-frequency generators 11 and 31 can be connected to the Furnaces can be attached or combined separately into an assembly.

The leveling device 2 consists essentially of a hopper 22 and rollers 21, in which the chunks 4 are pressed to a uniform layer thickness h. Instead of rollers, scrapers or other pressing devices can also be used.

The heating process now takes place as follows: The one with e.g. Trucks of tar-containing chunks 4 of different sizes arrive via a slide 5 in the direction of arrow 51 onto the conveyor belt 13 running in the direction of arrow 14. As can be seen, the individual chunks 4 have different distances a from the upper high-frequency electrode 12, that is to say in to some extent warmed differently. The output of the furnace 1 is now such that after passing through this furnace, the chunks 4 leaving this furnace have a temperature of approximately 80 to 100 ° C., ie are plastically deformable. Because of this plastic deformability, the lumps can then be pressed relatively easily between the rollers 21 to a uniform layer height h. The chunks leaving the rollers 21 with a reasonably constant layer height h then pass a scraper 23 onto the conveyor belt 33 and are transported here in the direction of the arrow 34 on the belt 33 lying next to one another as gently as possible through the oven 3. The individual chunks 4 are now approximately the same distance b from the upper electrode 32, so that approximately uniform heating of all the pieces to the required final temperature of 170-200 ° C. is achieved. The chunks 4 leaving the furnace 3 then enter a container 6, e.g. in a truck. From here, the material - as indicated by arrow 61 - is brought to the road construction site for reuse.

Due to the two-stage heating process in the high-frequency field explained above, a relatively rapid and uniform heating of the resulting demolition material and thus an ongoing supply of new construction sites possible.

Claims (2)

1. Apparatus for the capacitive high-frequency heating of lump material containing asphalt or tar, in particular of material which comes from road surfaces and which is to be re-used, to a final temperature of 170-200°C, characterised by a first capacitive continuous furnace (1), in which the lump material (4) carried between the electrodes (12, 13) can be heated at 80-100°C until it is plastically deformed, a following mechanical levelling device (2), in which the material (4) carried can be deformed to have a substantially uniform layer thickness (h), and a following capacitive continuous furnace (3), in which the material (4) which is at a substantially uniform distance (b) from the upper electrode (32), can be heated to the final temperature.

2. Apparatus as claimed in claim 1, characterised in that the continuous furnaces (1, 3) and the levelling device (2) are installed in transportable containers.

Images