DE3911425A1 - METHOD AND DEVICE FOR THE ENVIRONMENTALLY FRIENDLY PREPARATION OF ASPHALTIC MATERIAL WITH REUSED OLD ASPHALT - Google Patents

Abstract

A process and an apparatus are provided for environmentally safe preparation of an asphaltic mixture using recycled asphalt and the addition of fresh material such as gravel, chips or sand, the recycled asphalt portion M A being prepared in a first drum device 1 and the fresh material portion being prepared in a second drum device 2, and the exhaust gases, laden with harmful substances, from the first drum device 1 being passed into the burner area of the second drum device 2. Here, the second drum device 2, which is operated in counterflow, is split up into two sections 13 and 14, in which arrangement the fresh material M N is prepared in the first section 13, and the harmful substances (CH x, CO) contained in the exhaust gases from the first drum device 1 are burnt out in the second section by intensive mixing with the burner flame, and the hot gases arising here are then passed into the first section 13 of the second drum device 2 in order to prepare the fresh material M N. <IMAGE>

Description

The invention relates to a method and an apparatus for environmentally friendly preparation of asphalt mix with reuse used old asphalt and addition of new material such as  Gravel, grit or sand, with the old asphalt portion in one Most drum device and the new material share in two reprocessed drum device and the polluted waste gases from the first drum device into the burner area of the second drum device can be initiated.

Such a method and a corresponding device for this are known from DE-OS 34 41 382. There, the old asphalt part is heated in the first rotating drum device in a cocurrent process under the conditions of largely avoiding damage to the old bitumen, in a second rotating drum device the new material becomes higher than the old asphalt part in the countercurrent process heated, and the separately and heated to different temperatures old asphalt and new material parts after leaving the respective drum devices in at least one further mixer and there if necessary with renewed heat supply and addition of fresh bitumen and filler material to the end product set. The exhaust gases from the first drum device containing C H _x and CO and containing the finest bitumen particles are introduced directly into the second drum device and heated to such an extent under the influence of the burner acting in the second drum device that the pollutants are burned or decomposed, the exhaust gases further heated in the second drum device are used together with the burner gases to heat the new material to temperatures above those of the old asphalt. It is also seen before that the gas pipe leading from the first drum device opens into the second drum device immediately adjacent to the burner, ie the pollutant-laden exhaust gases from the first drum device are transported as close as possible to or into the burner flame.

The operation of such a system described above, which has been carried out in the past years, has shown that the CH _x and CO contents in the exhaust gases of the first drum device through the introduction into the second drum device, which is driven at a higher temperature, by combustion, however, have not yet been completely reduced be eliminated.

This would require the second drum device with an even higher tempera ture between about 800 to 1000 ° C, and the exhaust gas from the first drum device as evenly as possible with the hot combustion gases of the burner of the second drum device tion can be mixed. The high temperature causes disadvantageous Way that the new material is heated too high and therefore not immediately after leaving the second drum device of the first drum device released old asphalt portion in A compulsory mixer can be added because this old asphalt portion is heated to a maximum of only 220 °, advantageously to 180 °.

It is therefore an object of the present invention to provide a method and also a device which, on the one hand, significantly improve the known environmentally friendly method, in particular, completely remove CH _x and CO components from the exhaust gases to be released to the environment, and on the other hand Please ensure that the Neuma material processed in the second drum device is processed to a maximum of 300 ° C, but advantageously only up to the optimal temperature of approx. 200 ° C.

This object is achieved for the above-mentioned method by the fact that the second drum device works in countercurrent and is essentially divided into two sections, in which he processed the first section of the new material portion and before reaching the second section, in which the burner is arranged with its burner flame, is led out of the second drum device, the polluted exhaust gases from the first drum device in the second section of the second drum device are intensively mixed with the combustion gases of the burner flame and the pollutants such as CH _x , CO and finest bitumen particles burned out and then the entire exhaust gases as hot gas for processing the new material portion through the first section and then led out.

In contrast to the known methods described above, it can be achieved on the basis of this proposed solution that the pollutants in the exhaust gases from the first drum device in the burner area of the second drum device are completely burned out, ie the CH _x and CO components are destroyed, on the other hand but the new material with the desired optimal temperature processed and can be removed from the drum device.

The intensive mixing of the exhaust gases advantageously takes place from the first drum device with the combustion gases of the burner the second drum device in that the exhaust gases with swirl in initiated the second portion of the second drum device will.

Here the swirl of the exhaust gases is caused by a tangential introduction same in the second section.

This above-described introduction of the exhaust gases into the second Ab ensures a particularly intensive mixing with the Combustion gases.

The burner flame is advantageous by appropriate introduction the primary air also swirls into the burner.

The swirl of the exhaust gases can match the swirl of the burner flame or the combustion gases either rectified or opposite be.

The formation of a special one, only the burnout of the pollutants reserved section of the drum device allows a precisely defined flame or gas flow, which burns out the Promotes pollutants to train. In particular, by the be  special swirling of the exhaust gases and possibly also the primary air for the burner intensive mixing of the burner flame achieved on the one hand with the exhaust gases to be burned out on the other hand will.

In a slightly different embodiment of the invention, the exhaust gases from the first drum device already the primary air of the burner second drum device mixed in an adjustable ratio will.

Those emerging from the second section are advantageous Exhaust gases cooled down, so that in the first section of the second New material processed when the drum exits the drum device Drum device immediately before the start of the second section the second drum device through the exhaust gases to a maximum of 300 ° C is heated. This cooling of the exhaust gases takes place, for. B. by a spray water at the transition area from the first to the second cut the drum device.

This cooling process with regard to the exhaust gases at the predefined point le inside the drum device allows a process on the one hand appropriate temperature determination for that for further processing intended new material and on the other hand already an er ste cooling of the exhaust gases, so that they may already be without further cooling down through the downstream filter systems can be carried out without destroying them.  

The old asphalt portion is advantageous in a cocurrent processed drum device processed.

This mode of operation of the first drum device ensures one gentle treatment of the old asphalt part.

The object of the invention, a device for To carry out the method according to the invention solved in that the second drum device one in the counter current-working drum and essentially divided into two Lich trained sections is divided, with the first from cut, starting from the first bulkhead, conveyors intended for the new material to be processed in this section are in the second section, which is from the first section an outlet device for the new material is delimited the burner is arranged and immediately adjacent to or in the burner ner a supply line for that from the first drum device touching pollutant-laden exhaust gas is provided.

This design of the second drum device ensures that there are two procedurally defined areas, the an area exclusively for the pollutant burnout and the other area exclusively for the thermal treatment of the New material share is provided.

The second section of the second drum device is advantageous stationary compared to the first section, i.e. not turning out educated.  

This design of the second section allows a constructive simpler design of the burner arrangement and the feed lines for the exhaust gas to be introduced in this section from the first Drum device.

The one that closes the second section to the outside is advantageous second end wall as a feed line for the exhaust gases from the first stream training device.

Since the burner is also arranged in this second end wall, can one in the Burner integrated design can be achieved.

The feed line is advantageously designed in a spiral shape and takes place the introduction of the exhaust gases in this supply line tangentially into the second section.

This training allows a special twist control of the incoming exhaust gases.

Further advantages of the device result from the subclaims Chen 15.) to 20.).

An embodiment of the device is based on the attached Drawings explained.  

It shows

Fig. 1 is a system diagram of an asphalt Aufbereitungsan location,

Fig. 2 is a view of the second drum device in the plant according to Fig. 1,

Fig. 3 is a partial view with respect to the second Abschnit tes of the second drum device according to Fig. 2,

Fig. 4 is a partial view of a different imple mentation form according to FIG. 3 and

Fig. 5 is an axial plan view of the burner side of the second drum device, and FIG. 3.

The device proposed for carrying out the method according to the invention forms part of an asphalt preparation plant, as is shown schematically in FIG. 1.

The asphalt processing plant essentially works with two drum devices 1 and 2 working in parallel, of which the drum device 1 for the processing of the old asphalt portion M _A in cocurrent and the second drum device 2 for the processing of the new material. Share M _{N works} in countercurrent. Both drum devices 1 and 2 are arranged according to mixer 3 and 4 , in which the old asphalt portion M _A and the new material portion M _N are merged and merged into the asphalt mix M _G to be processed.

Bitumen B and filler material F are added to the asphalt material.

The old asphalt portion M _A is deducted from a storage device 5 via a wall scale 6 and passed into the drum device 1 , whereby it is passed through the interior of the drum device 1 heated by the burner 7 in direct current.

This drum device 1 is provided at its end opposite the burner 7 with a schematically indicated exhaust pipe 8 and connected via this to the second drum device 2 , the exhaust pipe 8 adjacent to the burner 9 or possibly directly opening into it.

In this second drum device 2 , the new material portion M _N to be processed therein is withdrawn via a belt scale 10 from a storage device 11 and on which the burner 9 is opposite the end wall 12 and cut in countercurrent through the first section 13 until shortly before Start of the second section 14 transported through, heated and then deployed from the second drum device 2 .

Adjacent to the end wall 12 , the second drum device 2 has an exhaust gas disposal line 15 , which is connected to a filter dust system 16 . From this filter dedusting system 16 , the exhaust gases are released into the environment by means of a ventilation device 17 .

The heated asphalt mixture contents M _A and M _N in the drum devices 1 and 2 are taken up by a first mixer 3 , which can be designed, for example, as a double-shaft, forced and continuous mixer. In this mixer 3 fresh bitumen B from a bitumen storage container 18 and filler material F from a filler storage container 19 are withdrawn and added, mixed together and heated so that the desired final temperature is maintained in certain proportions .

The mixer 3 can be followed by a structurally corresponding second mixer 4 . Finally, the completely prepared asphalt mix M _{G is drawn off} from the second mixer 4 and made available in a loading device 20 for removal.

In FIGS. 2 to 5 is then the real object of the invention He, namely the special design of the second Trommelvor device 2 shown in more detail.

The second drum device 2 is essentially divided into two sections 13 and 14 , which have different lengths.

The first section 13 is closed at one end by a first end wall 12 , which end wall can contain both the total gas discharge 15 and an addition device (not shown in the figures) for the new material M _N to be prepared in the second drum device 2 .

The other end of the first section of the second drum device 2 is adjacent to the second section 14 of the second drum device 2 and at this point a cooling device 21 is provided, which is designed, for example, as water injection. Here, the evaporation energy of the water is used in particular for cooling the hot gases. The Wassereindüsungsvorrich device consists, for example, of an annular, water-carrying distributor pipe with several nozzles distributed over the pipe length. The purpose of this arrangement is to cool the hot gases as evenly as possible over the entire drum cross section.

The second section 14 of the drum device 2 is closed to the outside by the second end wall 22 , which is designed as a line 23 for the approached by the first drum device and polluted exhaust gas. In this end wall 22 , the burner 9, which is only indicated schematically in FIG. 1, is provided as a burner 24 arranged centrally to the longitudinal axis 25 of the second section 14 .

In the embodiment described here, the diameter of the second section 14 is made smaller compared to the diameter of the first section 13 of the drum device 2 , further the longitudinal axis 25 of the second section 14 is offset upwards relative to the longitudinal axis 26 of the first section 13 , so that at the transition point between the first section 13 and two tem section 14 of the drum device 2 below the second section 14 there is a distance which contains the outlet device 27 for the new material M _N.

On the inner wall of the first portion 13 of the drum device, not shown in the figures, known conveying devices are provided which move the new material M _N introduced into the first end wall 12 by the rotation of the drum device 2 , in the described embodiment rotates only the first section 13 is transported to the outlet device 27 .

The feed line 23 for the exhaust gas from the first drum device 1 is, seen in the axial direction, formed spirally, so that the exhaust gases introduced there are introduced tangentially into the interior of the two-th section 14 of the drum device 2 , namely annularly along the walls of the second Section 14 and concentric to the burner flame of the burner 24th This burner 24 receives the necessary for the combustion of the fuel primary air through the supply line 28 , which may optionally also be formed from that it introduces the primary air tangentially into the burner 24 and thus the burner flame experiences a swirl. The swirl of the burner flame in turn and the swirl of the exhaust gas supplied through the feed line 23 can be of the same or opposite.

In another, shown in Fig. 4, supply line 23 for the exhaust gases and supply line 28 for the primary air of the burner 24 are connected to one another by the line 29 , that is, part of the exhaust gases from the first drum device 1 and the necessary primary air are already mixed in a certain ratio before being fed to the burner 18 . The exhaust gases, which are not supplied via the burner of the drum device, are fed tangentially to the section 14 of the drum device 2 via the feed line 23 . Corresponding devices for setting this mixing ratio are not shown in the drawings.

Also not shown in the drawings are structural details relating to the mounting of the second drum device 2 and other measures known to the person skilled in the art.

The compared to known devices and thus performed drive differently with respect to the second drum device trained asphalt preparation plant works as described below.  

The introduced at the end wall 12 and for the preparation before seen virgin material M _N is by the rotation of the first section from the second drum device 2 and the conveyor devices provided therein at a certain speed, which can be changed, through this first section 13 Exit device 27 transported. The new material M _N should not have a temperature higher than 300 ° C at its outlet, namely then together with the old asphalt portion M _A prepared in the first drum device 1 in the downstream mixers 3 and 4 and with addition of fresh bitumen B and filling material F can be brought together without further storage and further processed, namely to the final asphalt mixture M _G to be used for installation in roads etc.

If the new material M _N reaches too high a temperature when the exit device 27 is reached, it is necessary to cool the very high-temperature heating gases from the second section 14 of the drum device 2 , this is done by a cooling device 21 , which is designed, for example, as water injection . The energy required to evaporate the water droplets is extracted from the hot gases, which results in a very effective cooling effect.

These heating gases have a temperature of up to approx. 1000 ° C. when they enter the first section 13 of the drum device 2 , since this is necessary for the combustion of the pollutants (CH _x , CO and the finest bitumen particles). These pollutants are contained in the exhaust gas of the first drum device 1 . The burner 24 in the two th section 14 of the drum device 2 must therefore develop much hotter hot gases, which are required for the combustion of pollutants, than would be necessary solely for the preparation of the new material.

In summary, the above-described design of the second drum device 2 within the overall asphalt preparation plant ensures that fresh asphalt mix M _G can be produced, whereby on the one hand a not inconsiderable proportion of old asphalt from broken roads etc. can be used, on the other hand the The processing of the old asphalt contaminants arising from the afterburning can be removed from the total exhaust gases of the two drum devices, so that the cleaned total exhaust gases after they have flowed through filter systems etc. can be easily discharged into the free atmosphere.

Claims (20)

1. A process for the environmentally friendly processing of asphalt mix using reused broken asphalt and addition of new material such as gravel, grit or sand, the old asphalt portion processed in a first drum device and the new material portion in a second drum device and the pollutant-laden exhaust gases from the first drum device are introduced into the burner area of the second drum device, characterized in that the second drum device works in countercurrent and is essentially divided into two sections, where in the first section the new material Proportion prepared and before reaching the second section, in which the burner is arranged with its burner flame, is led out of the second drum device, the pollutant-laden exhaust gases from the first drum device in the second section of the second drum device with the combustion gases from the burner flame mixed intensively and the pollutants such as CH _x , CO and the finest bitumen particles burned out and then all the exhaust gases as hot gas for the preparation of the new material portion are passed through the first section and then out. 2. The method according to claim 1, characterized is characterized by the intensive mixing of the exhaust gases the first drum device with the combustion gases of the Burner of the second drum device takes place in that the exhaust gases with swirl in the second section of the second Be initiated drum device. 3. The method according to claim 2, characterized records that the swirl of the exhaust gases by tangential Introduction of the same in the second section is effected. 4. The method according to claim 2, characterized records that the burner flame by appropriate Introduction of the primary air is swirled into the burner. 5. The method according to claim 4, characterized records that the swirl of the exhaust gases the swirl of the bren nerflamme or the combustion gases is rectified. 6. The method according to claim 4, characterized records that the swirl of the exhaust gases the swirl of the bren nerflamme or the combustion gases is opposed. 7. The method according to claim 1, characterized records that the exhaust gases from the first drum device  already the primary air of the burner of the second drum device can be added in an adjustable ratio. 8. The method according to claim 1, characterized notes that the out of the second section tendency hot gases are cooled down, so that in the first Ab cut new material from the second drum device when leaving the drum device immediately before the start of the second section of the second drum device the hot gases are heated to a maximum of 300 ° C. 9. The method according to claim 5, characterized records that the cooling of the hot gases by injection hen water at the transition area from the first to the second Ab cut the drum device takes place. 10. The method according to claim 1, characterized shows that the old asphalt portion in a DC working drum device is processed. 11. Device for carrying out the method according to claims 1 to 10, characterized in that the second drum device ( 2 ) is a counter-current working drum and essentially divided into two differently shaped sections ( 13 and 14 ), respectively in the first section ( 13 ), starting from the first end wall ( 12 ), conveying devices for the new material ( M _N ) to be processed in this section ( 13 ) are provided, in the second section ( 14 ), which is separated from the first section ( 13 ) is separated by an outlet device ( 27 ) for the new material ( M _N ), the burner ( 24 ) is arranged and directly adjacent to or in the burner ( 24 ) is a feed line ( 23 ) for the pollutant-laden material originating from the first drum device ( 1 ) Exhaust gas is provided. 12. The apparatus according to claim 11, characterized in that the second section ( 14 ) of the second drum device ( 2 ) with respect to the first section ( 13 ) is stationary. 13. The apparatus according to claim 11, characterized in that the second section ( 14 ) outwardly closing second end wall ( 22 ) is designed as a feed line ( 23 ) for the exhaust gases from the first drum device ( 1 ). 14. The apparatus according to claim 13, characterized in that the feed line ( 23 ) is formed spirally, and the introduction of the exhaust gases in this feed line ( 23 ) takes place tangentially in the second section ( 14 ). 15. The apparatus according to claim 11, characterized in that the second section ( 14 ) has a smaller diameter than the first section ( 13 ). 16. The apparatus according to claim 15, characterized in that the second section ( 14 ) with its longitudinal axis ( 25 ) with respect to the longitudinal axis ( 26 ) of the first section ( 13 ) is offset upwards. 17. The apparatus according to claim 16, characterized in that the outlet device ( 27 ) for the new material ( M _N ) is provided in the transition region of the first section ( 13 ) to the second section ( 14 ). 18. The apparatus according to claim 11, characterized in that the feed line ( 23 ) for the exhaust gases from the first drum device ( 1 ) is connected to the feed line ( 23 ) for the desire to burn (primary air) of the burner. 19. The apparatus according to claim 11, characterized in that a feed device ( 15 ) for a coolant is provided in the transition region of the first section ( 13 ) to the second section ( 14 ). 20. The apparatus according to claim 19, characterized records that the coolant is water.