LU82376A1 - DEVICE FOR DRYING AND WARMING TAR OR BITUMEN-COVERED MINERAL MIXTURES - Google Patents

Description

* «« · * ». · «

The invention relates to a device for drying and heating tar or bitumen-coated mineral scraps, with a treatment chamber with heating gas pipes, in which the bituminous mixture is moved and heated by heat transfer.

The increasing scarcity of crude oil and the impending depletion of natural asphalt stocks make it necessary to break up the old, destroyed or damaged bituminous coverings for the repair of roads or other bituminous traffic areas and to rebuild the demolition material and to use it again for repair or new construction . In order to bring the demolition material back into a processable state, it is necessary to crush large pieces of material and then to dry and heat them in order to remove the bituminous binder such as *

P

Sa 620 - 2 - to liquefy and obtain a workable, bituminous mineral mixture.

However, the softening of the initially lumpy demolition material presents considerable difficulties, since the heat supplied penetrates only slowly into the mostly relatively coarse material and because the material for liquefying the bitumen must be heated to a temperature at which volatile bitumen gases escape can catch fire. There is also the danger that the bitumen will start to burn when heated 2U and develop here- *, »with a foul-smelling, gray smoke that pollutes and annoys the environment to a high degree.

In order to avoid this disadvantage, devices for reprocessing bituminous paving materials are known, in which the mineral mixtures already coated with bitumen are indirectly, i.e. without direct exposure to the flame. For example, a device is known (magazine "Bitumen" 3/1978, pp. 94-96) which has a double-walled mixing drum, in the interior of which pure mineral substances, i.e. Rocks not covered by bitumen, such as when preparing a new asphalt mix, are heated to the required installation temperature by a burner flame and then sprayed with separately preheated bitumen, while asphalt paving is introduced into the outer drum surrounding the inner drum * This asphalt paving is in the annulus heated, where it falls ia- * aer again on the hot jacket of the inner drum when rotating the drum and is heated and melted in the process. The melted demolition material is then mixed with the newly prepared road construction material and installed.

This known device has the disadvantage that even a slight overheating of the inner drum leads to a considerable * Sa 620 - 3 - * · »« *

Smoke formation in the outer drum leads, so that the inner drum must always be run at full load. This in turn means that only a certain percentage of the total asphalt mixture produced can be obtained from demolition material. It is therefore only possible to reuse a certain part of the demolition material obtained in the construction of a new road.

In another known device (magazine "Bitumen» 1/1978, S · 22 and 23) the demolition material is heated in a rotating drum, in which heating gases are passed through pipes arranged in the drum, which pass through the old asphalt material running in counterflow Heat heat transfer In order to supply a sufficient amount of heat, it is necessary to arrange a large number of heating pipes inside the drum, so that the remaining between the heating gas pipes is relatively small in cross-section. The lumpy asphalt material filled into the drum therefore remains at the end of the task between the two Heating gas pipes hang slightly and clogs the passage cross section · In addition, over time, more and more asphalt material settles on the heating gas pipes, which acts as an insulation and severely affects the heat transfer · In addition, it occurs particularly at the discharge end of the drum, where it is particularly hot Heating gases enter, easy to separate the expired real bituminous material

The object of the invention is to avoid these disadvantages and to provide a device for drying and heating tar or bitumen-coated mineral mixtures, in particular for reprocessing bituminous road construction material, with which such mineral mixtures are brought to such a high temperature without smoke and odor nuisance can be processed and reinstalled like a newly produced bituminous mix *. Sa 620 - 4 -

This object is achieved with the invention in that the heating gas pipes are located on the underside of a plurality of transport surfaces arranged one above the other, each of which has at least one discharge point and on which the bituminous mixture is conveyed along to a discharge opening.

This configuration has the advantage that the bituminous mineral mixture to be dried and warmed is heated by direct convection and radiation without direct contact with the flame and is inevitably transported through the treatment room. On the one hand, it is heated directly from below by the transport surfaces and is heat-treated from above, but at the same time is forcibly pushed over the transport surfaces so that it cannot bake on them.

Since several transport surfaces are arranged one above the other in the treatment chamber, the residence time of the material to be heated in the treatment chamber is so long that sufficient liquefaction of the bitumen can also be achieved with lower heating gas temperatures than are required in the known methods and devices. Therefore, hardly any vapors develop in the treatment chamber and coking of the bitumen and the associated smoke development is avoided with certainty.

According to a further feature of the invention, the heating gas tubes can be designed as flat hollow bodies and attached to the long

Transport areas are in contact or limited by them. The heating gas pipes are expediently only a short distance from the surface of the bituminous mixture lying on the next lower transport surface. With this training, an excellent heat transfer from the heating gases to the mineral mixture is achieved.

Sa 620 - 5 - ♦%

In order to supply the mineral mixture with even more heat, heating pipes can also be arranged above the upper transport surface and / or to the side of the transport surfaces, which are located at a short distance from the bituminous mixture to be heated.

According to a further feature of the invention, the heating tubes arranged below two transport surfaces arranged one above the other are connected to one another and the heating gases flow through them in succession.The heating gas tubes thereby form, as it were, heating coils which each flow on the material material moving on the transport surfaces Flow around the top, the bottom and a long side · Here, the heating pipes run crossways to the conveying direction of the transport surfaces and form two pipe systems, both of which are connected to a common heating gas chamber in the middle of the treatment chamber and one of which is the upper half of the treatment chamber in countercurrent to the bituminous mixture to be dried and from which the other pipe system runs through the lower half of the treatment chamber in cocurrent with the mixture to be dried. This arrangement has the advantage that the mineral mixture to be heated is neither at its entry point in the treatment chamber is still exposed to very hot gases at its exit point. Nevertheless, the best possible heat transfer is achieved by the heating gas flow in the upper part of the treatment chamber, which takes place in counterflow to the material movement, in order to bring the material to a higher temperature as quickly as possible. In the lower part of the treatment chamber, on the other hand, the flowing material flow no longer meets gases that are getting hotter and hotter, but is heated until it is discharged at an approximately constant temperature, since it is important to expose the mixture to be heated to the heat for a longer period, so that the heat can penetrate into the interior of any material that may still be present.

* b

Sa 620 - 6 -

The heating gas source can expediently be a gas or oil burner arranged outside the treatment chamber "whose combustion chamber is at a distance from the treatment chamber and which is provided with a cooling jacket" through which a part of the heating gases leaving the treatment chamber flows "which then flows to the fuel gas admixed and together with this are returned to the dealers. This configuration has the advantage that on the one hand the thermal energy generated by the burner is fully utilized, but on the other hand the temperature of the heating gases introduced into the treatment chamber can be controlled and reduced to such an extent that the bituminous material to be heated cannot overheat.

«

To ensure that no vapors or bitumen gases get into the atmosphere, the treatment chamber expediently has a fume extraction line leading to the combustion chamber, which feeds any gases and vapors that arise during the drying and heating of the mineral mixture to the combustion. These vapors are expediently drawn off from the treatment room with a suction fan and blown directly into the flame of the burner.

The transport surfaces used in the device according to the invention can, for example, be vibratory conveyors. Loading. However, it is particularly expedient if the transport surfaces are conveyor troughs of scraper chain conveyors which are covered on the top side by the heating gas pipes and whose endless scraper pads run successively over several of the transport surfaces arranged one above the other. With such a design, it is ensured that the bituminous mix to be heated does not bake or get stuck on the transport surfaces heated from below, since it is removed from the scrapers or bars of the scrapers. Sa 620 - 7 - »chains are constantly scraped off and transported on. Furthermore, there is a particularly good heat transfer, since the mix to be heated is constantly circulated and loosened up when it falls on the next lower transport surface and is transported further in the opposite direction.

It is particularly expedient if the scraper chain of each scraper conveyor runs over a set of at least four transport surfaces arranged one above the other and if the strands of the scraper chain are guided over drive and Umfcehrroller so that the scraper chain after painting the top transport surface first to the lowest transport surface and then Runs across the middle transport surfaces of the set before returning to the top transport surface. This configuration has the advantage that the scraper chain always alternately passes through hot and cold zones when sweeping over the transport surfaces, takes up and carries small amounts of molten bitumen with it during transport, which acts as a lubricant for the chains of the scraper chain and special maintenance of the conveyors Makes redundant «

In order to compensate for the different elongation of the scratch chains due to the uneven heating, tensioning devices can be provided for the scratch chains.

Further features and advantages of the invention result from »the following description and the drawings, by which a particularly advantageous embodiment of the invention is explained in more detail using an example. It shows!

1 shows a device for drying and heating bituminous mineral mixtures according to the invention in longitudinal section and ·% .......

Sa 620 - 8 - ««

Fig. 2 shows the subject of Fig. 1 in cross section.

The device for drying and heating b itun en mined mineral genes shown in the drawings, in particular for the reprocessing of a broken, bituminous, road surface, is designated in its entirety by 10 and consists essentially of a treatment chamber 11 and a heating gas source 12, which is outside the Treatment chamber 11 is arranged and connected to it by a conical heating gas nozzle 13. The treatment can 11 has a substantially rectangular shape and is lined with a heat-insulating material 14. Instead, the floor 15, the ceiling 16, the longitudinal walls 17 and 18 and the end walls 19 and, 20 themselves can consist of a heat-insulating and / or refractory material.

In the interior of the treatment chamber 11, eight transport surfaces 21, 22, 23, 24, 25, 26, 27 and 28 are provided, which are arranged at a vertical distance from one another and extend approximately horizontally in the longitudinal direction of the treatment chamber 11. Here, the top transport surface 21 is at a distance from the ceiling 16 and the bottom transport surface 28 is at a distance from the floor 15 of the treatment chamber 11. The transport surfaces 21 to 28 consist of thick, wear-resistant steel plates, under which heating gas pipes 29, 30, 31 »32, 33, 34, 35 and 36 are arranged. This Hoizgasrohre consist of flat hollow bodies which extend over almost the entire length of the transport surfaces 21 to 28 and the top of which is formed by the thick steel plates which represent the transport surfaces. The lower floor 37 and the end walls 38 and 39 of the heating gas channels consist of a thin, heat-conducting material, for example of steel or copper sheet, *

Sa 620 - 9 - ♦

As can be seen from FIG. 2, upstanding side winches 40 and 41 are arranged on the longitudinal sides of the transport surfaces 21, 23, of which the side winches 40 abut or are formed by the longitudinal walls 17 and 18 of the treatment chambers 11 and of which the side walls 41 at the same time limit the heating gas connecting lines 42 to the treatment room 11, which are arranged in the longitudinal sides 17 and 18 of the treatment room 11 and two superposed heating gas pipes 29 and 30 or 30 and 31 or 31 and 32 or 32 and 33 and 33 and Connect 34 or 34 and 35 or 35 and 33 with each other. As a result, the transport surfaces 21 to 28 together with the side walls 40 and 41 and the urinary floors 37 of the heating gas tubes 29 to 33 form closed conveying troughs 43 which are only open on their end faces.

It can be seen from FIG. 2 that 11 heating gas tubes 44 are also arranged under the ceiling 16 of the treatment chamber and that the heating gas tubes 44 and 29 to 33 run transversely to the conveying directions 45 and 46 of the transport surfaces 21 to 28. Here, the heating gas pipes 44, 29, 30 and 31 in the upper part 47 of the treatment chamber and the heating gas pipes 33 »34,% - 35 and 36 in the lower part 48 of the treatment chamber de form a coherent pipe system A and B, both of which are combined by the in the center of the treatment chamber 11 arranged heating gas pipe 32 are connected to the heating gas nozzle 13 of the heating gas source 12. The heating gases entering the heating gas pipe 32 thus flow successively through the heating gas pipes 31, 30, 29 and 44 of the upper pipe system and then exit through an outlet opening 49 in the upper part 47 of the treatment room into a flue gas discharge line 50. Another part of the heating gases entering the hot gas pipe 32 flows down through the heating gas pipes 33, 34, 35, 33 of the lower pipe system B and leaves the lower part 48 of the treatment chamber 11 through a lower outlet opening 51 into the flue gas discharge line 50, * r

Sa 620 - 10 -

As can be seen from FIG. 1, a material feed hopper 52 is arranged near the end wall 19 in the ceiling 16 of the treatment canister 11 and opens out above one end of the uppermost transport surface 21. A material discharge opening 53 is provided in the bottom 15 of the treatment scanner 11 approximately vertically below this material feed hopper 52 and contains a chute 54 which adjoins the end of the undisturbed transport surface 28. The lumpy demolition material poured through the material feed hopper 52 onto the uppermost transport port curses 21 is pushed by two scraper chain conveyors 55 and 56 over the transport surfaces 21 to 28 to the discharge opening 53 and is heated to approximately 180 ° C. during this process through the treatment can . It can be seen from Fig. 1 that the transport surfaces or conveyor troughs 21 to 28, in which the scraper chain conveyors 55 and 56 operate, are offset in the longitudinal direction in such a way that the next lower transport surface projects in relation to the transport surface above it in the longitudinal transport direction. For example, the transport surface 22 protrudes over the transport surface 21 in its conveying direction 45 over its end face 39 by the dimension 1 ^, while the transport surface 23 projects over the transport surface 22 in the transport direction 46 by the same dimension lg. As a result, each transport surface has a discharge point 57 at the front end, where the mixture moved along the trancport surface by the Ketton scraper conveyor 55 or 56 is thrown onto the next lower transport surface and transported there in the opposite direction.

In the illustrated embodiment, each of the two scraper chain conveyors 55 and 56 consists of two link chains 58 running along the side walls 40 and 41 of the conveying troughs 43, which are connected to one another by scraper irons 59, which are arranged at a longitudinal distance from the chain and via the transport surfaces 21 to 28 Strip and take the mix lying directly on the heated channel floor and push it along the transport surfaces. Instead of a chain scraper conveyor, a movable steel mesh belt of a different design can also be used.

The scraper chain 58, 59 is guided in each scraper chain conveyor 55 or 56 over drive rollers 60 and deflection rollers 61, 62, 63, 64 and 65 in such a way that, after covering the hottest transport area, it reaches the coldest transport surface of the tranport surface set which it has coated the dreams 66 of the scraper chain 58 »59 de3 upper scraper chain conveyor 55, which sweeps over the set X consisting of the transport surfaces 21, 22, 23 and 24, from the uppermost, coldest transport surface 21 of the set via the reversing rollers 61 and 62 and the drive roller 60 immediately to the lowest, warmest transport surface 24 of the set · Here, the scraper chain 58 changes its direction of rotation and is then again guided over the middle transport surfaces 23 and 22 of the upper transport surface set, reversing the direction of travel, until it returns to the uppermost transport surface o 21 Transport chain which is in contact with the one just filled n, has cooled the still relatively cold mix relatively far, is warmed up again in the area of the lowest transport surface and there already absorbs melted bitumen components, which act as a lubricant and ensure the easy mobility of the chain links as the scraper chain continues to pass through the treatment room

Similarly, the strands 66 of the scraper chain 58, 59 of the lower scraper chain conveyor 56 are guided around the deflection rollers 61, 62, 63, 64 and 65 and around the drive roller 60 such that the chain from the top, hottest transport surface 25 to the coldest transport surface 28 of the lower Trar.sportflâchonsatz consisting of the transport areas 25 »26, 27 and 28 is guided, from where they then over the middle Trans-

Sa 620 - 12 - m * * port surfaces 27 and 26 return to the top transport surface 25 of sentence Y ·

In the embodiment 3b shown here, the hoizgas source 12 consists of a gas or oil burner 67, the combustion chamber 68 of which is arranged at a distance from the echanification chamber 11 and is connected to it by the hot gas nozzle 13 (FIG. 2) · Dio walls 69 des Brcnnraunes 63 are lined with refractory material 70 and surrounded by a cooling jacket 71 at a distance, which is flowed through by a portion of the heating gases 72, which leave the treatment canals 11 through the Keizgasrohre 44 and 36. For this purpose, the annular space 73 formed by the cooling jacket 71, which surrounds the combustion chamber 68, is connected to the flue gas discharge line 50 via a branch line 74 and is equipped with a suction fan 75. By means of this suction fan, part of the heating gas © is withdrawn from the flue gas outlet 50 and passed into the annular space 43, where the flue gases, which have meanwhile cooled, cool the detection space 68. Then they are passed into the heating gas nozzle 13, where they mix with the hot fuel gases 76 of the burner and lower their temperature, so that the temperature of the nozzle 13 coming from the heating gas into the treatment chamber does not substantially exceed 250 ° C.

In the upper part 47 of the treatment chamber 11, an extractor line 80 is connected, into which a suction fan 81 is installed and which opens into the combustion chamber 68 in such a way that the vapors and volatile bitumen constituents drawn off from the treatment chamber 11 directly into the flame 82 of the burner 67 are blown and burn there.

The device works as follows: Sa 620 - 13 - »· 4 * ·.

9

The like by fretting or breaking up a road or the like. Bituminous mineral conglomerate obtained is first broken down to a grain size and filled into the material hopper 52 such that there is always material in the hopper. The bituminous mixture 100 sliding onto the top transport surface 21 is carried along by the scraper bars 59 of the scraper chain 53 of the upper scraper chain conveyor 55 in the direction of the arrow 45 and pushed over the transport surface 21. Here, the mixture is heated over a wide area from below by direct contact with the trancport surface heated from below and from above by radiant heat which generates the heating gases flowing through the uppermost heating tubes 44.

At the end of the transport surface 21, the bituminous mixture 100 falls at the discharge point 57 onto the next lower transport surface 22, where it is again picked up by the scraper chain 53 of the scraper chain conveyor 55 and pushed in the direction of arrow 46 over this transport surface until it is at the discharge point 57 falls again on the next lower transport surface 23. Here it is then transported again in the direction of arrow 45 “from the trancport chain to Aowurfctelle 57, where it falls on the fourth transport surface 24. The process is then repeated in the area of the lower transport surface set Y, where the lower scraper conveyor 56 takes over the transport of the bituminous mixture 100 via the lower transport surfaces 25, 26, 27 and 23 until the bituminous mixture at the discharge point 57 of the lowest transport surface 28 via the Slide 54 is discharged from the device *

All the way through the treatment chamber 11, the bituminous mixture is heated from below and above and from the sides by the heating gases flowing in the heating gas tubes 44, 29 to 36 and 42 to a final temperature of 185 ° C., with which it is at the Discharge opening 53 emerges. The r • i · ». ÿ. * Sa 620 - 14 - 4 4

Heating gases are generated in the combustion chamber 68 and mixed with cooler heating gases, which are removed from the flue gas discharge line 50, into which the heating gases emerging from the treatment chamber 11 escape. The slightly volatile bitumen gases and vapors generated when the mixed material is heated are passed through the extractor line 80 to the combustion chamber added and burned in flame 82

The transport speed of the scraper chain conveyor and the burner output are controlled depending on the moisture and the temperature of the bituminous mineral mixtures to be heated. As a rule, the transpreging surfaces should have a temperature of 250 ° C. and the layer thickness of the material transported over the transport surfaces should not significantly exceed 50 mm. The length of the entire path that the material travels in the device according to the invention is then chosen such that the mineral to be heated reaches a temperature of 180 ° to 185 ° C at the discharge point

In Fig. 1 there are 83 tensioning devices which hold the scraper chains 58 of the scraper conveyors 55 and 56 under tension when they change their length during operation when heated.

The invention is not limited to the exemplary embodiment. For example, it is also possible to provide other continuous conveyors for conveying the bituminous mineral mixture through the treatment heads, which ensures that heat can reach the material to be dried as freely as possible. For example, baffle plate conveyors, screw conveyors or vibratory conveyors could also be used. Of course, it is also possible to generate the heating gases required for heating in a different way or to use other heat generators to heat the transport surfaces and to generate the radiant heat that acts on the surface of the mineral mixture, if this is the case is possible with economically justifiable effort.

% «4 *. · X '» »*

Claims (7)

2. Apparatus according to claim 1, characterized in that the heating gas tubes (44, 29 to 36) are designed as flat hollow bodies and on the transport surfaces (21 to 28) or are limited by these and that the heating gas tube · (29 to 36, 44) have a small distance from the surface of the bituminous mixture (100) lying on the 'Sa 620 - II - * »* next lower transport surface. 3, Device according to claim 1 or 2, characterized gekennzeich- * net that also above the top transport surface (21) and / or laterally next to the transport surfaces (21 to 28) heating pipes (44) are arranged, which are at a short distance from the bituminous mixture (100) to be heated. 4 · Device according to one of claims 1 to 3 # characterized by • J indicates that the heating pipes (29 to 36) arranged under two superimposed transport surfaces (21 to 28) are connected to one another and successively by the heating gases (76) Flows through the device according to one of claims 1 to 4, characterized in that the heating pipes (29 to 36, 44) run transversely to the conveying direction (45 or, 46) of the transport surfaces (21 to 28) and two pipe systems (A and B) form, both of which are connected in the middle of the treatment chamber (11) to a common heating gas source (12) and of which the one pipe system (A) feeds the upper half (47) of the treatment chamber (11) in countercurrent the bituminous mixture to be dried and of which the other pipe system (B) runs through the lower half (48) of the treatment chamber (11) in «direct current with the mixture (100) to be dried« * 6 · device according to one of claims 1 to 5, characterized, that the heating gas source (12) is a gas or oil burner (67) arranged outside the treatment chamber (11), the combustion chamber (68) of which is at a distance from the treatment chamber (11) and which is provided with a cooling jacket (71) which is flowed through by part of the heating gases leaving the treatment chamber (11), which is then mixed with the fuel gases (76) '4L ...... "- St 620 - III -. and together with these are passed back into the treatment chamber (11). 7. Device according to one of claims 1 to 6, characterized in that the treatment chamber (11) has a leading to the combustion chamber (68) Dunstabzug3leitung (80), which during the drying and heating of the mineral mixture feeds any gases and vapors to the combustion. 8. Device according to one of claims 1 to 7, characterized. characterized in that the transport surfaces (21 to 28) are vibratory conveyors. 9. Device according to one of claims 1 to 7, characterized in that the transport surfaces (21 to 28) of the heating gas pipes' (44, 29 to 36) top covered conveyor troughs (43) of scraper chain conveyors (55, 56), the endless Scraper chains (58) run successively over several of the transport surfaces (21 to 28) arranged one above the other. 10. Device according to one of claims 1 to 9 », characterized in that the scraper chain (58) of each scraper-O conveyor (55, 56) via a set (X or Y) of at least four superposed transport surfaces (21 to 24 or 25 bi3 28) runs and that the strands (66) of the scraper chain (58) are guided over drive and reversing rollers (60 to 65) in such a way that the scraper chain (58) sweeps over the top transport surface (21 or 25) runs first to the lowest transport surface (24 or 28) and then over the middle transport surfaces (22, 23 or 26, 27) of the set before it returns to the uppermost transport surface (21 or 25).