FR3062468A1 - ROTARY DRUM DRYER FOR DRYING AGGREGATES - Google Patents

Abstract

The dryer comprises a rotating drum (4) for receiving the aggregates, lifting blades (10) disposed on the inner surface (12) of the drum (4) for raising the aggregates and causing them to fall back due to rotation of the drum (4), and a deflector (30) mounted within the drum (4) to prevent aggregates raised by the tipping vanes (10) from falling into an interruption zone (32) located vertically under the baffle ( 30).

Description

Holder (s):

ERMONT Simplified joint-stock company.

O Extension request (s):

(® Agent (s): LAVOIX.

® ROTARY DRUM DRYER FOR DRYING AGGREGATES.

(57) The dryer comprises a rotary drum (4) intended to receive the aggregates, lifting vanes (10) arranged on the internal surface (12) of the drum (4) for raising the aggregates and causing them to fall due to the rotation of the drum (4), and a deflector (30) mounted inside the drum (4) to prevent the aggregates raised by the lifting vanes (10) from falling back into an interruption zone (32) located vertically below the deflector (30).

FR 3 062 468 - A1

Rotary drum dryer for aggregate drying

The present invention relates to the field of rotary drum dryers for the drying of aggregates, for example for the production of mixes, in particular mixes for road surfaces.

To produce asphalt for road surfaces, it is possible to dry and heat aggregates, then mix dry and hot aggregates with binder, in particular a bituminous binder. As an option, it is possible to mix dry and hot aggregates with aggregates from recycled asphalt, also called "asphalt aggregates".

For drying the aggregates, it is possible to use a dryer comprising a drum mounted to rotate about its axis inclined with respect to the horizontal plane, lifting vanes arranged on the internal surface of the drum to raise the aggregates due to the rotation of the drum and make them fall down, forming a curtain of aggregates inside the drum, and a burner generating hot gases circulating in the drum.

In operation, the drum is supplied with wet and cold aggregates. Due to the rotation of the drum, the aggregates are raised by the lifting vanes and fall back forming a curtain of aggregates crossed by the hot gases produced by the burner. The aggregates advance inside the drum due to the successive lifting and the inclination of the axis of the drum relative to the horizontal plane, being gradually dried and heated.

The fumes generated by the hot gas passing through the aggregate curtain and leaving the drum are recovered and filtered. In order to ensure good performance, the fumes must be neither too cold, as this involves the risk of condensation, nor too hot, as this results in overconsumption of energy.

Depending on the shape of the lifting vanes, the lifting vanes raise a more or less large amount of aggregates, the curtain of aggregates formed in the rotating drum is more or less dense, and the heat exchange between the hot gases and the aggregates is more or less intense, which influences the temperature of the fumes leaving the dryer.

It is possible to provide adjustable lifting vanes, in order to be able to adjust the dryer as a function of the production to be carried out, in particular as a function of the humidity of the aggregates used, the temperature of the asphalt asphalt desired at the outlet of the production plant '', or a recycling rate of asphalt.

FR3034786A1 discloses a rotary drum dryer comprising adjustable lifting vanes pivotally mounted on the drum. However, the blade adjustment mechanism is complex.

One of the aims of the invention is to provide a rotary drum dryer for the drying of aggregates which makes it possible to adjust the temperature of the fumes, while being of simple design and use.

To this end, the invention provides a dryer for drying aggregates, comprising a rotary drum intended to receive the aggregates, lifting vanes arranged on the internal surface of the drum to raise the aggregates and cause them to fall due to the rotation. of the drum, and a deflector mounted inside the drum to prevent the aggregates raised by the lifting vanes from falling back into an interruption zone situated vertically under the deflector.

According to particular embodiments, the dryer comprises one or more of the following optional characteristics, taken individually or in any technically possible combination:

- the deflector is adjustable so as to modify the horizontal extent and / or the vertical extent of the interruption zone in which the aggregates do not fall;

- the deflector can be oriented around an orientation axis to modify the deflector setting;

- the orientation axis is parallel to a longitudinal axis of the drum or coincides with a longitudinal axis of the drum;

- the deflector is eccentric relative to the longitudinal axis of the drum;

- It includes an adjustment mechanism configured to control the adjustment of the deflector from outside the drum, in particular from one end of the drum;

- the deflector is mounted inside the drum so that it can remain stationary during the rotation of the drum;

- The deflector is mounted inside the drum by means of at least one bearing mounted on a support which is fixed inside the drum and which rotates with the drum;

- the deflector has the shape of a plate;

- it includes a burner to generate a flow of hot gas inside the drum;

- the dryer is a simple dryer or a mixer-dryer, co-current or counter-current.

The invention and its advantages will be better understood on reading the description which follows, given solely by way of nonlimiting example, and made with reference to the appended drawings, in which:

- Figure 1 is a schematic view in axial section of a rotary drum dryer for drying aggregates;

- Figures 2 to 4 are cross-sectional views of the drum according to II-II in Figure 1, showing a deflector respectively in three different adjustment positions;

- Figures 5 to 7 are schematic views illustrating a control mechanism for adjusting the deflector; and

- Figures 8 to 10 are views similar to those of Figure 1, illustrating rotary drum dryers according to variants.

The rotary drum dryer 2 illustrated in FIG. 1 comprises a drum 4 having a longitudinal axis A-A ’. The drum 4 is tubular and extends along its longitudinal axis A-A ’. The drum 4 is rotatably mounted around its longitudinal axis A-A ’.

The longitudinal axis A-A ’of the drum 4 is oblique to a horizontal plane. The longitudinal axis A-A ’makes a non-zero angle with the horizontal plane and a non-zero angle with the vertical direction. The angle of inclination of the longitudinal axis A-A ’of the drum 4 relative to the horizontal plane is for example between 2 ° and 10 °, in particular between 3 ° and 5 °.

The drum 4 comprises an inlet 6 for wet and cold aggregates, formed by an axial end of the drum 4, and an outlet 8 for dry and hot aggregates, formed by the opposite axial end of the drum 4.

The inlet 6 is located at a height greater than that of the outlet 8, due to the inclination of the longitudinal axis A-A ’of the drum 4 relative to the horizontal plane. In operation, the aggregates circulate in the drum 4 progressively advancing from the inlet 6 towards the outlet 8.

The dryer 2 comprises lifting vanes 10 disposed on the internal surface 12 of the drum 4. The lifting vanes 10 are configured to lift the aggregates present in the drum 4 due to the rotation of the drum 4, and make them fall back forming an aggregate curtain inside the drum 4.

The lifting vanes 10 are arranged in a drying section 18 of the drum 4. The aggregate curtain is generated in the drying section 18 during the rotation of the drum 4.

The dryer 2 here comprises several rows 14 of lifting vanes 10. Each row 14 comprises several lifting vanes 10 distributed circumferentially on the internal surface 12 of the drum 4. The lifting vanes of each row 14 are located at the same axial position along the longitudinal axis A-A 'of the drum 4.

The dryer 2 is configured for a circulation of hot gas axially in the drum 4 for drying the aggregates. In operation, the hot gases pass through the aggregate curtain formed by the lifting vanes 10 and dry the aggregates.

The dryer 2 in Figure 1 is a counter-current dryer. The dryer 2 is configured for a circulation of hot gas axially in the drum 4 in the opposite direction to the aggregates. In operation, the hot gases circulate axially in the drum 4 from the outlet 8 towards the inlet 6.

In the example illustrated, the dryer 2 comprises a burner 20 configured to generate hot gases circulating axially inside the drum 4. The burner 20 is arranged to form a flame inside the drum 4. The burner 20 is at exit 8.

The flame is generated in a flame section 22 of the drum 4. The flame section 22 is distinct from the drying section 18. The drying section 18 is here located upstream of the flame section 22, considering the direction of circulation of the aggregates from entry 6 to exit 8.

The dryer 2 comprises a supply device 24 for supplying the inlet 6 with wet and cold aggregates. The feeding device 24 is for example a belt conveyor arranged to discharge the aggregates into the inlet 6.

The dryer 2 comprises a smoke collector 26 for recovering the fumes generated by the hot gases and leaving the drum 4. In the counter-current dryer 2 of FIG. 1, the smoke collector 26 is disposed at the inlet 6.

As can be seen in FIGS. 1 and 2, the dryer 2 comprises a deflector 30 arranged inside the drum 4 to prevent aggregates raised by lifting blades 10 from falling back into an interruption zone 32 situated vertically under the deflector 30.

In operation, the aggregates raised by the lifting vanes 10 do not fall back into the interruption zone 32. The aggregate curtain (reference C in FIG. 2) is therefore interrupted in the interruption zone 32. The interruption 32 forms a free passage of aggregate for the hot gases. The hot gases passing through the aggregate curtain do not exchange heat with aggregates in the interruption zone 32. The larger the interruption zone 32, the less the hot gases exchange heat with the aggregates.

The deflector 30 is located in the drying section 18. The deflector 30 extends over a fraction of the length or over the entire length of the drying section 18. The deflector 30 here extends over a fraction of the length of the section drying 18.

When the dryer 2 comprises several rows 14 of lifting vanes 10, the deflector 30 extends axially opposite a row 14 or several rows 14.

The deflector 30 has for example the shape of a plate. The deflector 30 extends parallel to the longitudinal axis A - A ’.

The deflector 30 is mounted inside the drum 4 so that it can remain stationary during the rotation of the drum 4. In operation, the deflector 30 does not rotate with the drum 4, but remains stationary.

The interruption zone 32 has a horizontal extent substantially equal to the vertical projection of the deflector 30 in a horizontal plane. The interruption zone 32 has in particular a length L (Figure 1) taken along the vertical projection of the longitudinal axis A-A 'on a horizontal plane, and a width I (Figure 2) taken perpendicular to the vertical projection of the longitudinal axis A-A 'on a horizontal plane.

The deflector 30 is adjustable so as to modify the horizontal extent of the interruption zone 32, and in particular the width I of the interruption zone 32.

The deflector 30 is here mounted inside the drum 4 so as to be orientable about an orientation axis which is preferably parallel to the longitudinal axis A - A 'of the drum 4, and which coincides here with the 'longitudinal axis A - A' of the drum 4.

As shown in FIGS. 2 to 4, a modification of the orientation of the deflector 30 modifies the horizontal extent of the interruption zone 32, and more precisely the width I of the interruption zone 32.

The deflector 30 is movable between a first position (Figure 2) in which the horizontal extent of the interruption zone 32 is maximum and a second position (Figure 4) in which the horizontal extent of the interruption zone 32 is minimal.

The plate-shaped deflector 30 has a profile in view along the longitudinal axis A-A ’(Figure 2). The profile is arched here. Other profiles are possible. In a variant, the deflector 30 is substantially planar and has a rectilinear profile.

In the first position (Figure 2), the profile of the deflector 30 extends substantially horizontally, and in the second position (Figure 4), the profile of the deflector 30 extends substantially vertically. The deflector 30 pivots about 90 ° between the first position and the second position.

The deflector 30 can take intermediate positions between the first position and the second position, as illustrated in FIG. 3.

The deflector 30 is eccentric relative to the longitudinal axis A - A ’. The rotation of the deflector 30 around the longitudinal axis A-A ’is accompanied by a displacement of the deflector 30 along a circular path around the longitudinal axis A-A’.

This causes a displacement of the interruption zone 32 inside the drum 4 and a modification of the vertical extent of the interruption zone 32 together with the modification of the horizontal extent of the interruption zone 32.

In the example illustrated, in the first position, the deflector 30 is situated vertically above the longitudinal axis A - A ’. In the second position, the deflector 30 is located substantially at the level of the longitudinal axis A - A ’. The deflector 30 moves about 90 ° around the longtudinal axis A-A ’between the first position and the second position.

In the example illustrated, the deflector 30 is here rotatably mounted inside the drum 4 by means of an internal bearing 34 mounted on the drum 4, here on an internal support 36 fixed to the drum 4 and which rotates with the drum 4, and an external bearing 38 mounted outside the drum 4. The axes of rotation of the internal bearing 34 and of the external bearing 38 coincide with the longitudinal axis A - A 'of the drum 4.

This assembly makes it possible both to keep the deflector 30 stationary in rotation about the longitudinal axis A-A 'during the rotation of the drum 4, and to modify the orientation of the deflector 30 around the longitudinal axis A-A' to adjust the extent of the interruption zone 32.

In a possible variant, the deflector 30 is rotatably mounted inside the drum 4 by means of two internal bearings 34 mounted inside the drum 4, on internal supports fixed to the drum 4 and which rotate with the drum 4. The deflector 30 is here connected to the shaft 42 by substantially radial arms 44.

The dryer 2 comprises a control mechanism 40 for controlling the adjustment of the deflector 30.

The control mechanism 40 here comprises a shaft 42 extending axially inside the drum 4. The shaft 42 is coaxial with the drum 4 and rotatably mounted relative to the drum 4, here by means of the internal bearing 34 and of the outer bearing 38. The deflector 30 is carried by the shaft 42 so that the deflector 30 is rotatable relative to the drum 4 and that the rotation of the shaft 42 modifies the orientation of the deflector 30 around the longitudinal axis A - A '.

The control mechanism 40 is configured for adjusting the deflector from the outside of the drum 4, in particular from one end of the drum 4, here the inlet 6.

The control mechanism 40 comprises an actuating device 46 for rotating one end of the shaft 42 exiting through one end of the drum 6, here by the inlet 6.

Figures 5 to 7 illustrate the actuating device 46 by illustrating different positions corresponding to the positions of the deflector 30 in Figures 2 to 4.

The actuating device 46 is here actuated by an actuator. It includes an actuator 48 connected to the end of the shaft 42 for adjusting the angular position of the shaft 42.

The actuator 48 is here a linear shareholder which has one end 48A articulated on a fixed support 49 and another opposite end 48B articulated on an arm 50 linked in rotation to the shaft 42. The extension and contraction of the jack 46 allow to adjust the angular position of the shaft 42, and therefore the orientation of the deflector 30.

The actuator 48 is for example an electric actuator, a hydraulic actuator or a pneumatic actuator.

Alternatively, the control mechanism 40 comprises a rotary actuator, for example an electric motor, coupled to the shaft 42, for example by a gear system and / or a linkage.

Alternatively, the actuator 46 is manually operated. In this case, the actuator 48 is for example replaced by a crank coupled to the shaft 42 for adjusting the angular position of the shaft 42.

In operation, the drum 4 is rotated about its longitudinal axis A-A '(arrow R in Figures 2 to 4) and supplied with aggregates (reference G in Figures 2 to 4) wet and cold through its inlet 6 The aggregates are raised by the lifting vanes 10 and fall back forming a curtain of aggregates (reference C in Figures 2 to 4) traversed by the hot gases circulating inside the drum 4. Due to successive lifting, aggregates progress gradually from inlet 6 to outlet 8, being gradually dried and heated.

The aggregate curtain is interrupted in the interruption zone 32 located under the deflector 30. The hot gases pass through the interruption zone 32 without exchanging heat with the aggregates. The larger the interruption zone 32, the less the hot gases exchange heat with the aggregates and the hotter the fumes. The smaller the interruption zone 32, the more the hot gases exchange heat with the aggregates, and the colder the fumes.

Thus, the deflector 30 makes it possible to modify the thermal efficiency of the dryer 2. This is done in a simple and inexpensive manner without having to have adjustable lifting vanes requiring a complex adjustment mechanism or complex adjustment operations. The deflector 30 and the extent of the interruption zone 32 are adjusted in a simple manner.

The dryer 2 of FIG. 1 is a simple counter-current dryer, configured to ensure only the drying of the wet and cold aggregates, which emerge dry and hot from the drum 4.

However, the invention is not limited to a simple counter-current dryer, but is generally applicable to a simple dryer or a mixer-dryer, cocurrent or counter-current.

Figure 8 illustrates a co-current dryer (or parallel streams) provided with a deflector 30. The dryer 2 of Figure 8 differs from that of Figure 1 in that the burner 20 is arranged to generate a flow of hot gas flowing in the drum 4 in the same direction as the aggregates, from the inlet 6 towards the outlet 8. The flame section 22 is upstream of the mixing section 18. The smoke collector 26 is located at the exit 8 instead of being located at entry 6. The actuating device 46 is also located at exit 8 instead of being located at entry 6.

Figure 9 illustrates a counter-current dryer-mixer 2. The dryer-mixer 2 of Figure 9 differs from the dryer of Figure 1 in that the drum 4 comprises, downstream of the flame section 22, a mixing section 52. The dryer-mixer 2 comprising a pole 54 for the introduction of a binder into the kneading section 52. The drum 4 is provided on its internal surface 12, in the kneading section 52, with mixing vanes 56 making it possible to mix the aggregates with the binder.

As an option, as illustrated in FIG. 9, the dryer-mixer 2 comprises a recycling ring 58, located axially between the drying section 18 and the mixing section 52, and making it possible to introduce into the drum 4 aggregates coming from '' recycled asphalt, and already coated with binder.

Figure 10 illustrates a co-current dryer-mixer 2. The dryer-mixer 2 of Figure 10 differs from that of Figure 9 in that the burner 20 is arranged to generate a flow of hot gas flowing in the drum 4 in the same direction as the aggregates, from the inlet 6 towards the outlet 8. The flame section 22 is upstream of the mixing section.

The invention is not limited to the illustrated exemplary embodiments. Variants are possible.

For example, the dryers 2 of Figures 1 and 8 to 10 have burners 20 configured to generate a flame inside the drum 4. Alternatively, the burner 20 can be omitted is replaced by a hot gas generator separate from the drum 4 is connected to the drum 4 to supply it with hot gases.

Claims (11)

1. -Drier for the drying of aggregates, comprising a rotary drum (4) intended to receive the aggregates, lifting vanes (10) arranged on the internal surface (12) of the drum (4) for lifting the aggregates and making them fall down due to the rotation of the drum (4), and a deflector (30) mounted inside the drum (4) to prevent the aggregates raised by the lifting vanes (10) from falling back into an interruption zone ( 32) located vertically under the deflector (30). 2. - dryer according to claim 1, wherein the deflector (30) is adjustable so as to modify the horizontal extent and / or the vertical extent of the interruption zone (32) in which the aggregates do not fall. 3. - A dryer according to claim 2, wherein the deflector (30) is orientable about an orientation axis to modify the setting of the deflector. 4. - dryer according to claim 3, wherein the axis of orientation is parallel to a longitudinal axis (A - Aj of the drum (4) or coincides (A - Aj with a longitudinal axis of the drum (4). 5. - dryer according to any one of claims 2 to 4, wherein the deflector (30) is eccentric relative to the longitudinal axis (A - Aj of the drum (4). 6. - A dryer according to any one of claims 2 to 5, comprising an adjustment mechanism (40) configured to control the adjustment of the deflector (30) from outside the drum (4), in particular from one end of the drum. 7. - A dryer according to any one of the preceding claims, wherein the deflector (30) is mounted inside the drum (4) so as to be able to remain stationary during the rotation of the drum (4). 8. - dryer according to any one of the preceding claims wherein the deflector (30) is mounted inside the drum (4) by means of at least one bearing (34) mounted on a support (36) which is fixed inside the drum (4) and which rotates with the drum (4). 9. - A dryer according to any one of the preceding claims, wherein the deflector (30) has the form of a plate. 10. - A dryer according to any one of the preceding claims, comprising a burner (20) for generating a flow of hot gas inside the drum. 11. - A dryer according to any one of the preceding claims, the dryer being a simple dryer or a mixer-dryer, co-current or counter-current. 1/4