SE509095C2 - Methods and apparatus for preparing asphalt - Google Patents

Abstract

The invention relates to a device for preparing asphalt, comprising a cylindrical drum (3). The drum is rotatable about its longitudinal axis which is inclined downwards the horizontal plane. The drum has a feeding means (9) arranged at the intake end of the drum and adapted to feed material, in the form of suitable fractions of stone material and/or used asphalt, to the drum; feeding means (15, 17) for supplying a binder; a discharge means (13) arranged at the discharge end of the drum and adapted to discharge prepared asphalt paving material from the drum; a drive means (19) for rotating the drum; a burner (11) arranged at the intake end; and a plurality of carrying means (33) arranged in the drum. The carrying means which extend from the intake end of the drum to the discharge end thereof, receive the material from the feeding means and convey it through the drum. Each carrying means comprises a wall portion (35) which is connected to the wall (41) of the drum and which extends inwards from the wall of the drum, and a groove-shaped portion (37) which is connected to the wall portion and which is terminated with a longitudinal free edge (55), which is arranged at a distance from the wall and in front of the wall portion seen in the direction of rotation of the drum. The carrying means are so designed and mutually arranged that the material in a carrying means (57) during one revolution falls over the edge, is caught by the anteriorly situated carrying means (59), seen in the direction of rotation, and is returned to the carrying means which the material initially left via the drum wall portion (61) of the two neighbouring means. The invention also concerns a corresponding method.

Description

509 095 10 15 20 25 30 35 which consists of crushed stone with a certain average coarse size, there are also fine fractions, such as stone flour and gravel. Due to the high velocity of the gases, the fine fractions are blown through the drum and out through the outlet. There they must be taken care of by filtration, which leads to extra costs, extra handling and reduced gas flow through the drum. Furthermore, the device is not usable for asphalt recycling, because the supply of materials containing binders leads to unwanted emissions of toxic gases. The toxic gases are created by the binder's contact with the hot combustion gases when the material falls through the drum, above all in the second section but also in the third section. Immediately after the flame, the gases have too high a temperature. In the third section, especially at the beginning of it, there is also a risk that toxic gases are formed during new production of asphalt, for the hot combustion gases when the material falls down because binders are added and then exposed through them.

U.S. Pat. No. 4,738,539 discloses another known device which is constructed in substantially the same manner as the device in CH-628 381. with the jet of hot combustion gases after the binder has been added. The two known devices have an inefficient effect. however, the material does not come into direct contact, which happens towards the end of the drum. building that makes them unnecessarily long.

SUMMARY OF THE INVENTION An object of the invention is to provide a method and an apparatus for preparing asphalt, which are as applicable to asphalt recycling as to new production.

Another object of the invention is to provide a method and device for preparing asphalt, in which the material is heated faster and more efficiently than is the case in the prior art without risk of emission of dangerous gases caused by too high a temperature of the bin. 15 20 25 30 35 509 095 demedent and without problems having to take care of fine particles that otherwise pollute the environment. The objects are achieved with a device and a method according to the invention as defined in claim 1 and 8, respectively. The preambles of claims 1 and 8 are based on CH-628 381.

Brief Description of the Drawings The invention and further advantages thereof will be described in more detail below by way of example with reference to the accompanying drawings, in which: Fig. 1 is a schematic side view of an asphalt preparation apparatus, according to an embodiment of the invention; Fig. 2 is a schematic sectional view of a drum included in the device of Fig. 1; and Fig. 3 is a schematic enlargement of a detail in Fig. 2 and shows an alternative embodiment.

Description of embodiments As shown in Fig. 1, the device 1, according to an embodiment of the invention, comprises a cylindrical drum 3, which has an input end 5 and an output end 7; a first input means 9; a burner 11; an output means 13; a second input means 15; a third input means 17, a drive means 19 and a frame 21.

The drum 3 has a front end 29 and a rear end 30.

The ends 29, 30 are attached to the frame 21.

The support 63 is adjusted so that the drum 3 is inclined relative to the frame 21 and comprises an adjustable support 63. the horizontal plane.

The first input means 9, hereinafter referred to as meter 9, comprises a material container 23 and a conveyor 25, which is preferably a belt conveyor.

The feeder 9 supplies material which either constitutes one or more fractions of crushed stone such as macadam and / or stone flour or wholly or partly constitutes old asphalt to be reused, to the drum 3 at its feed end 5 through a hole in the front end 29 of the drum 3.

The material is heated in the drum. This process will be described in more detail below.

The second feed means 15, referred to below and the third feed means 17, supply binder sub-injectors 15, hereinafter referred to as end injectors 17, to the material at the feed end 5 and at the discharge end 7, respectively. that dust in the material is bound. The end injector 17 fills a suitable amount of binder in the discharge means 13 so that an asphalt with desired properties is produced.

When recycling used asphalt, any supply of stone material or binder depends on the age of the asphalt with several properties and on which properties you want the finished asphalt to have.

The burner 11, which is a burner conventional for the purpose, is arranged in the feed end 5 of the drum 3 so that the mouth of the burner 11 is placed in a conventional manner inside the end 29 of the drum 3 or approximately in the plane of the end 29, as shown in the above mentioned scriptures. The burner 11 comprises a fan which drives a controllable flow of combustion gases through the drum 3.

The drum 3 is supported by four support wheels 19 included in the drive means 19, two on each side of the drum 3. The drive means drives two of the support wheels for rotation of the drum 3 about its longitudinal axis. The ends 5, 7 of the drum 3 are rotatably fitted in the ends 29, 30, which thereby help to hold the drum 3 in place. Each support wheel 19 has a friction lining which abuts the outside of the drum.

At the discharge end 7 of the drum 3, the discharge means 13, which in this embodiment consists of a substantially conventional mixer feeder, is arranged for discharging the material with the added binder during mixing. The mixer feeder 13 inserts a piece into the drum 3 through the rear end 30 and catches the material. The mixer feeder 13 has a semi-cylindrical lower part and a discharge member in the form of a longitudinal shaft with inclined blades attached thereto which, when the shaft rotates, protrude and at the same time remix the material. The finished asphalt is discharged by the mixer feeder 13 to a waiting besides a truck bed 31. advantageous in this context because its open cone holder, the mixer feeder 13 is a structure which means that it also acts as an outlet for the gases, mainly water vapor and hot air. , which is driven through the drum 3. It has the advantage that the mixer feeder 13 and the material in it are kept warm by means of the energy in the gases. This avoids unnecessary cooling of the material and you can even achieve additional heating. However, an additional chimney opening in the end 30 may be required to achieve sufficient flow through the drum 3.

The parts of the device described above are arranged on a frame transportable by truck, such as the frame 21 which is a demountable frame. As a result, the device becomes mobile and easily transportable by truck to any manufacturing site. An essential factor for enabling such a compact device to fit on, for example, such a demountable frame 21 is the internal construction of the drum 3, which will now be described in more detail.

As shown in Fig. 2, carrier means, or gutters, 33 are arranged inside the drum 3. The gutters 33 are elongate and run like internal flanges along the inside of the drum 3, substantially all the way from the feed end 5 of the drum 3 to its discharge end 7. Each gutter 33 comprises a radial wall portion 35 and one connected to the wall portion 35, is substantially flat and is in a longitudinal attachment portion The attachment portion 39 elongate supports 45 has a V-shaped cross-section and merges into the V-shaped tip in the rest of the wall-gutter-shaped, or curved, portion 37. The wall portion 39 thereof connected to the wall 41. of the drum comprises two interconnected portions 43, 45. The support portions 43, 509 095 10 15 20 25 30 the portion 35, while the leg ends of the V-shape, i.e. the support portions 43, 45 long side edges 47, 49 abut against the inside of the drum wall 41. The fastening portion 39 also comprises fastening means 51, such as threaded pins, which are fixed at the bottom of the gutter which the support parts 43, 45 can be said to form and which are arranged at suitable distances from each other along the support portions 43, 45. The fastening means 51 extend through holes in the drum. 3 wall 41 and are releasably anchored, as with nuts 53, on the outside of the drum 3. As a result, the gutters 33 are releasably connected to the drum 3. The V-set support portions 43, 45 of the fastening member distribute the forces to which the fastening portion is subjected by material present in the gutters 33. This construction differs from the construction in the known devices.

The gutter-shaped portion 37 forms a curved extension on the wall portion 35 and terminates with a free longitudinal side edge 55 at a distance from the wall 41. The sectional view in Fig. 2 shows the interior of the drum 3 seen from its feed end 5. The cross-section of the gutters 33 is hook-shaped. The drum 3 rotates clockwise in Fig. 2, ie the free edges of the gutters 33 lie in front of the wall portions 35 seen in the direction of rotation.

The belt conveyor 25 is arranged near the periphery of the drum 3 and throws the material into the grooves 33 through the hole in the front end 29. The grooves 33 are so designed and placed relative to each other that the material, which is shown as shaded areas in the grooves 33, during rotation, it moves around in a space delimited by two adjacent grooves, for example the grooves 57 and 59, the portion 61 of the wall 3 of the drum 3 which is located between the two grooves 57, 59 and an opening 60 which is formed between the grooves. 57, 59 in that they are arranged at a distance from each other, calculated in the circumferential direction of the drum 3.

During a rotation, starting when the groove 57 is at the top, the material in the groove 57 first falls out of it, past the opening between the grooves 57 and 59 and down on it, seen in the direction of rotation, in front of the groove 59, or more precisely on the back of the groove 59 wall portion 10 15 20 25 30 35 509 095 35. Then the material is dropped / rolled down on the wall portion 61 of the drum and spread over it. Gutter 57 has now reached its lowest position. On the way up, the material is thrown / rolled back down into the gutter 57. During this process, material moves due to the drum at the same time towards the discharge end 7, one 3 tilts in relation to the horizontal plane. In the end portion at the discharge end 7, the grooves 33 are slotted in the groove-shaped portion 37. Thereby the material falls out of the grooves 33 and down into the mixer feeder 13.

There are several variables which affect the possibility of providing a device which, in accordance with the invention, holds the material in the space so that it does not fall out through the opening 60. The variables are: the rotational speed of the drum 3; the design and placement of the gutters 33 in relation to each other and the amount of material in the gutters 33.

A relatively low rotational speed is desirable, so the main force effect on the material is gravity. This is in order to get a good mix of the material. An excessively high rotational speed causes the material to be pressed against the wall 41 and held in approximately the same position during a rotational revolution. This also prevents the transport of material through the drum 3.

The design of the gutters 57, 59 and the placement of them in relation to each other are made such that the gutters can support a considerable amount of material without the material falling out through the opening 60. The gutters should therefore be arranged more densely than in the known devices described above. and the free edge 55 should be extended so far that the gutter-shaped portion 37 can receive a suitably large amount of material. In the embodiment shown, the gutter portion 37 has a radius of curvature which is 0.1 m; is 2.2m and the number of gutters 33 is 12. the height of the wall portion 35 is 0.3m; The diameter of the drum 3 It can be noted in this context that the length of the drum in this pocket 37 in this embodiment constitutes a half cylinder. drawn embodiment is 4m. These dimensions are to be considered only as an example which satisfies the condition that the material does not fall through the interior of the drum 3 but essentially rotates in the space between two adjacent grooves 33 in the manner as described above.

It should be noted that the amount of material obviously has an impact. If an extremely large amount of material is fed into the gutters 33, it will fall over the edge 55 even if the space between the edge 55 and the wall 41 is small. However, conversely in the known devices it applies that the material will fall out between the gutters regardless of how little material is fed. The design and mutual placement of the gutters 33 are thus decisive for achieving the object of the invention. Thus, if the gutters are suitably designed and arranged in relation to each other and the amount of material is suitably adapted thereto, the rotational speed has no effect on the retention of the material in the space. Even at the lowest possible rotational speed, the material is retained in the said space. At the same time, it is still possible to keep the distance between two adjacent gutters 33 large enough for hot gases to enter the space and heat the material.

If you want to be able to supply more material without it falling out through the opening 60, you can achieve this by increasing the rotational speed. An upper limit for compensating for a larger amount of material by means of the rotational speed is reached when the rotational speed has a detrimental effect on the material's travel in space.

There are, of course, many combinations of the above-mentioned variables which provide a device according to the invention.

However, it is within the scope of a professional's ability to try out a suitable combination in a certain situation on the basis of the above description.

An advantage of the material traveling in a delimited space is that the problems with the prior art described above are avoided. This means that the material never falls down through the drum and comes into direct contact with the hottest combustion gases. At the same time, the confined space is not closed, as in the case of closed ducts, but hot gases have access to the space via the openings between the gutters 33. This eliminates the problem of toxic gases from recycled asphalt or from the smaller amount of binder added by means of sub-injector 15, while still providing efficient heating. Furthermore, the fine fractions are not blown out through the discharge end 7. Due to the constant movement of the material, an efficient mixing of hot air in the space for efficient heating of the material is achieved. a thin layer over a large surface, which gives a good expo- In the lower half of the drum 3, the material is dispersed in nering for the hot gases. In addition, since the jet of hot gases is not braked by material falling through it, a much more even temperature is achieved in the entire drum 3 than in the known devices, which further streamlines the process.

The device according to the invention has a significantly higher efficiency due to the improvements reported above in relation to the known devices. This means, among other things, that it can be made considerably shorter than the known devices at the same production capacity.

How much material is supplied, ie how much material per unit length each gutter 33 carries, is controlled not only by the appropriate degree of filling in the gutters 33 so that the material does not fall out through the opening 60 but also by, among other things, the type of material.

In the embodiment shown, both the feed speed and the rotation speed are adjustable so that the best results can be achieved in each case.

The above-described embodiment is only an unlimited example of how the device according to the invention can be embodied. As one skilled in the art will appreciate, numerous modifications are possible within the scope of the invention, which are defined in the appended claims. Below are some examples of modifications. 10 509 D95 10 15 20 25 30 35 The shape of the gutters 33 is variable. An example of a variant is shown in Fig. 3 with dash-dot-dotted lines starting from the fastening portion 39 and converging with the gutter-shaped portions 37. In this variant, the wall portion 35 does not constitute a continuation of the gutter-shaped portion 37 in its key direction, as in the embodiment described above, but forms an angle to this key direction. This means that the portion of the gutter-shaped portion 37 located closest to the wall portion 35 forms a wall which effectively prevents the material from falling off the wall portion of a gutter 33 when it falls down from the gutter located immediately above. There is a small risk of this in the embodiment described above, which, however, is more cost-effective to manufacture.

The gutter-shaped portion can, for example, be designed with a cross-sectional shape other than a half-cylinder shape, such as a polygonal or some asymmetrical shape.

The fastening portion can be made in any manner, although in the embodiment shown the angled support portions 43, 45 of the fastening portion 39 facilitate the movement of the material past the transition between the wall 41 of the drum 3 and the support members 33 and the construction of the fastening portion provides easily removable support means.

The size of the device depends on the desired capacity. As has been described above, the device, due to its unique construction, can be designed as a mobile, which is an advantage as those initially described. However, it is possible that the device does not possess known devices. also design the device as a stationary unit, whereby it can be made significantly larger than the mobile variants.

For mobile versions, the above-mentioned demountable frame is only one of many useful frames. A variant is also to build the device as a unit permanently anchored to a vehicle, such as a towing vehicle or a trailer.

Claims (10)

A device for preparing asphalt comprising a (3), the longitudinal axis inclined towards a horizontal cylindrical drum arranged for rotation about its longitudinal axis, and a pronation plane, and which has an feed end (5) feed end (7): an feed means (9) arranged at the feed end of the drum for feeding material, in the form of suitable fractions of stone material and / or used (15, a wide (13) discharge of finished asphalt mass from the drum; a burner asphalt (19) arranged in the drum; in the drum; a further feed means 17) for supplying binder to the material; the discharge end of the drum provided with discharge means for rotating the drum; one at the feed end (II) whose combustion gases are supplied to the interior of the drum; and a plurality of internal drums disposed (33), along the drum, carrying means connected to and extending for receiving the material from the feed means and transporting the material through the drum, each support means comprising one with the Wall (41) of the drum ) (35), from the wall of the drum, and a wall portion connected to the wall portion, (37), (55), which edge is spaced from the wall portion extending inwardly into a gutter-shaped portion terminating with a free, longitudinal edge and in front the wall portion seen in the direction of rotation of the drum, characterized in that the carrier means extend from the feed end of the drum to its discharge end and that the carrier means are so designed and mutually arranged that the material in a carrier member (57) falls over during a rotational revolution said free edge, is caught by the nearest front, seen in the direction of rotation and via it between the wall of the two (61) men is returned to the carrier member as the material inside, located carrier means (59) no. The adjacent carrier means located the portion of the trumpetally left. 12 509 095 10 15 20 25 30 35 Device according to claim 1, characterized in that each carrier member has a hook-shaped cross-section, the wall portion being substantially flat. Device according to claim 1 or 2, characterized in that said further input means (15) are arranged at the input end of the drum. The supply of binder to the material is known - (17) the supply of binder to the material is arranged at 4. Device according to claim 3, characterized in that a third input means for the output end of the drum and that the output means is arranged for output during mixing. Device according to any one of the preceding claims, characterized in that the wall portion comprises one (39) with two interconnected, (43, 45), and in the tip of the V-shape merges into the rest of the wall portion (35), (47, 49). ) towards the mounting portion of the drum wall elongate support portions which have a V-shaped cross section while those in the leg ends of the V-shape (41) Device according to claim 5, (39) extending through the wall of the drum until it abuts the inside. k n n e e - t e c k n a d that the fastening portion comprises the fastening organ side and is detachably fastened to the outside. Device according to one of the preceding claims, characterized in that it comprises a gear changer frame (21), which constitutes a frame on which the other constituent parts are arranged, in order to provide mobility of the device. A method of preparing asphalt by means of a device comprising a cylindrical drum (3), which is arranged for rotation about its longitudinal axis and which has an input end (5) and an output end (7), the longitudinal axis inclined in relation to the horizontal plane; the method comprising the steps of driving the drum to feed material, tera; in the form of suitable fractions of rock material and / or used asphalt, in the drum at its feed end to a plurality of carrier members (33) arranged inside the drum 10, which are connected to and extend along the drum and which contribute to remixing the material and transporting it through the drum; supplying hot combustion gases to the interior of the drum to add binder to the material; to discharge at the discharge end of the drum ready to heat the material; asphalt mass from the drum; and designing each carrier member to include a front portion (35) connected to the wall (41) of the drum (41) and a wall portion connected to the wall portion extending inwardly from the wall of the drum, (37), (55), which edge is spaced from the wall and a gutter-shaped portion terminating with a free, longitudinal edge of the wall portion seen in the direction of rotation of the drum, characterized by the steps of forming the carrier means so as to extend from the feed end of the drum to its discharge end; designing the support means and arranging them relative to each other so that the material in a predetermined loop (57), the material falling over during a rotational revolution, is caused to move around in said free edge, is caught by the carrier means located closest to the front, seen in the direction of rotation (59) and via the portion (61) located between the two adjacent carrier means initially left the material. of the wall of the drum is returned to the carrier means as 9. A method according to claim 8, characterized by the step of adjusting the feed of material into the drum so that the amount of material in the support means is maximized under the condition that it should be retained in said loop. 10. A method according to claim 8 or 9, characterized by the step of setting the rotational speed so that the rotation of the drum helps to retain the material in the loop.