EP0391768B1 - Drying and mixing drum with a burner for the preparation of bitumen coated products - Google Patents

Drying and mixing drum with a burner for the preparation of bitumen coated products Download PDF

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Publication number
EP0391768B1
EP0391768B1 EP90400821A EP90400821A EP0391768B1 EP 0391768 B1 EP0391768 B1 EP 0391768B1 EP 90400821 A EP90400821 A EP 90400821A EP 90400821 A EP90400821 A EP 90400821A EP 0391768 B1 EP0391768 B1 EP 0391768B1
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EP
European Patent Office
Prior art keywords
drum
burner
flame
blades
casing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP90400821A
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German (de)
French (fr)
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EP0391768A1 (en
Inventor
Guy Marconnet
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Ermont CM
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Ermont CM
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Publication date
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Priority to AT90400821T priority Critical patent/ATE79141T1/en
Publication of EP0391768A1 publication Critical patent/EP0391768A1/en
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Publication of EP0391768B1 publication Critical patent/EP0391768B1/en
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Classifications

    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
    • E01C19/02—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for preparing the materials
    • E01C19/10—Apparatus or plants for premixing or precoating aggregate or fillers with non-hydraulic binders, e.g. with bitumen, with resins, i.e. producing mixtures or coating aggregates otherwise than by penetrating or surface dressing; Apparatus for premixing non-hydraulic mixtures prior to placing or for reconditioning salvaged non-hydraulic compositions
    • E01C19/1013—Plant characterised by the mode of operation or the construction of the mixing apparatus; Mixing apparatus
    • E01C19/1027—Mixing in a rotary receptacle
    • E01C19/1031—Mixing in a rotary receptacle the mixture being discharged continuously
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
    • E01C19/02—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for preparing the materials
    • E01C19/10—Apparatus or plants for premixing or precoating aggregate or fillers with non-hydraulic binders, e.g. with bitumen, with resins, i.e. producing mixtures or coating aggregates otherwise than by penetrating or surface dressing; Apparatus for premixing non-hydraulic mixtures prior to placing or for reconditioning salvaged non-hydraulic compositions
    • E01C19/1013—Plant characterised by the mode of operation or the construction of the mixing apparatus; Mixing apparatus
    • E01C19/1027—Mixing in a rotary receptacle
    • E01C19/1036—Mixing in a rotary receptacle for in-plant recycling or for reprocessing, e.g. adapted to receive and reprocess an addition of salvaged material, adapted to reheat and remix cooled-down batches
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
    • E01C19/02—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for preparing the materials
    • E01C19/10—Apparatus or plants for premixing or precoating aggregate or fillers with non-hydraulic binders, e.g. with bitumen, with resins, i.e. producing mixtures or coating aggregates otherwise than by penetrating or surface dressing; Apparatus for premixing non-hydraulic mixtures prior to placing or for reconditioning salvaged non-hydraulic compositions
    • E01C2019/1081—Details not otherwise provided for
    • E01C2019/1086—Mixing containers having concentric drums
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
    • E01C19/02—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for preparing the materials
    • E01C19/10—Apparatus or plants for premixing or precoating aggregate or fillers with non-hydraulic binders, e.g. with bitumen, with resins, i.e. producing mixtures or coating aggregates otherwise than by penetrating or surface dressing; Apparatus for premixing non-hydraulic mixtures prior to placing or for reconditioning salvaged non-hydraulic compositions
    • E01C2019/1081—Details not otherwise provided for
    • E01C2019/109—Mixing containers having a counter flow drum, i.e. the flow of material is opposite to the gas flow

Definitions

  • the invention relates to a drying and coating drum for the preparation of bituminous coated products comprising an improved burner.
  • Devices for the preparation of bituminous coated products from aggregates and bitumen which are constituted by a drum comprising a cylindrical envelope in which the drying and heating of the aggregates introduced by one end of the drum and the coating are carried out. aggregates dried and heated with bitumen generally introduced in liquid form.
  • drum-dryers-wrappers are internally lined with lifting or agitating fins for the materials and the drum whose axis is slightly inclined in the direction going from its inlet end to its outlet end ensures the transport of solid materials, when it is rotated about its longitudinal axis.
  • the solid materials mainly constituted by the aggregates are therefore circulated in the longitudinal direction of the drum and are successively dried and heated then coated with bitumen.
  • the heat necessary to carry out the drying and heating of the aggregates and / or the reflow of the recycled coated materials is supplied to the drum by a burner penetrating axially through one of the ends of the envelope.
  • the burner can be introduced into the casing by its end receiving the virgin aggregates, generally designated as the inlet end.
  • the hot gases from the burner and the aggregates circulate in the same direction inside the drum.
  • the drum is thus generally separated into two zones, namely a first zone located between the inlet end of the drum and the end of the burner, in which the burner flame develops and in which the hot gases circulate and a second area around the burner body between the end of the burner and the outlet end of the drum, this second area not being subject to the circulation of hot gases from the burner.
  • This arrangement makes it possible to carry out the drying and heating of the aggregates in the first zone and the coating of the dried and heated aggregates in the second zone, by reducing the risks of degradation and ignition of the bitumen.
  • bitumen vapor and pellets constituted by a mixture of pulverulent and bitumen are thus favored, which is very harmful for the quality of the mixes produced.
  • the mixing is carried out in contact with the bottom of the drum, which affects the quality of the coated product.
  • the extraction fan ensures the transport of all the water vapor contained in the recycled material and passes it over the new bitumen, which promotes the distillation and vaporization of the bitumen by the "steam cracking" phenomenon. .
  • the object of the invention is therefore to propose a drying and coating drum for the preparation of bituminous coated products, from aggregates and bitumen, the drum having a cylindrical casing having a first end, or inlet end. by which at least part of the aggregates are introduced and a second end, or outlet end, through which the body of a burner enters the drum in its axial direction to an area remote from the outlet end, so as to develop a flame and ensure the circulation of hot gases along the length of the drum, in the direction opposite to the direction of circulation of the aggregates, from the end of the body of the burner, a means for injecting bitumen disposed in a drum coating zone situated around the body of the burner and means for rotating the drum around its axis, this drying and coating drum eur having a mixing zone around the burner body perfectly isolated from the flame zone when the drum is in service and ensuring the elimination of volatile products released by the bitumen in the mixing zone.
  • the part of the burner body located inside the drum is arranged coaxially inside a peripheral external sheath, free to rotate around the burner body and connected to the casing of the drum, one end corresponding to the end of the burner from which the flame develops carries a plurality of blades of radial direction with respect to the casing of the drum having faces inclined with respect to the longitudinal direction of the drum and constituting a gas suction turbine in the direction going from the second to the first end, during the rotation of the drum , and a screen against the radiation from the burner flame.
  • Figure 1 is an axial sectional view of the entire coating dryer drum.
  • FIG. 2 is a partial cross-sectional view along 2-2 of FIG. 1.
  • Figure 3 is a partial cross-sectional view along 3-3 of Figure 1.
  • FIG. 4 is a partial cross-sectional view along 4-4 of FIG. 1.
  • FIG. 5 is a partial cross-sectional view along 5-5 of FIG. 1.
  • Figure 6 is a cross-sectional view along 6-6 of Figure 1.
  • Figure 7 is a cross-sectional view along 7-7 of Figure 1.
  • Figure 8 is a cross-sectional view along 8-8 of Figure 1.
  • the coating dryer drum shown in FIG. 1 comprises a casing 1 of generally cylindrical shape comprising a first end 2 constituting its inlet end and a second end 3 constituting its outlet end.
  • the casing 1, in the operating position of the drum, is mounted on a platform so that its longitudinal axis 5 is inclined relative to the horizontal, the inlet end 2 being at a level higher than the level of the outlet end 3.
  • the casing 1 is also rotatably mounted on the platform, around its longitudinal axis 5.
  • vanes 7 ′ arranged along helices make it possible to very quickly introduce the aggregates into the second zone 8 of the drum.
  • the envelope 1 carries on its internal surface flat vanes 10 making it possible to ensure a certain agitation of the aggregates, without lifting these aggregates inside the drum.
  • the drum-dryer-coater comprises a zone 9 in which the internal surface of the casing 1 is filled with vanes 11 in shape of hooks to ensure a certain lifting of the aggregates inside the drum during its rotation.
  • This zone 9 constitutes a drying and heating zone, the aggregates being exposed to radiation of the flame and brought into contact with the hot gases circulating in the drum.
  • the drying and heating zone 9 occupies a substantial length of the drum and ends at an annular diaphragm 17 delimiting the zone in which the flame 14 of the burner develops. Downstream of the diaphragm 17, in the first part of the flame zone, a recycling ring 12 is arranged around the drum so as to allow the introduction of recycled materials into the drum.
  • the internal surface of the casing 1 of the drum comprises, in the zone situated between the diaphragm 17 and the recycling ring 12, anti-radiation vanes 13 whose shape makes it possible to protect the materials introduced into the drum against the radiation of the flame.
  • the blades 13 delimit, with the inner surface of the casing 1, successive pockets, the wall of which faces towards the interior of the drum, that is to say towards the flame 14 of the burner, avoids direct exposure of the materials.
  • Part 1a of the envelope 1 disposed in the vicinity of the outlet end 3 has a diameter greater than the diameter of the other parts of the envelope.
  • This part 1a is engaged by its end close to the outlet section 3 in a facade element 15 comprising an outlet opening 16 of the mixes produced in the drum.
  • the body 19 of the burner 20 which is fixed in rotation relative to the casing 1 of the drum penetrates inside the casing 1 in its axial direction.
  • the part of the body 19 located inside the drum is disposed axially inside a peripheral external sheath 22, free to rotate around the body 19.
  • the sheath 22 is rotatably mounted inside the support 18 by means of rollers 23 and around the body 19 of the burner, by means of rollers 24.
  • the fuel and the combustion air are supplied to the burner through the interior of the body 19 which has an outlet end 19a from which the flame 14 develops.
  • blades such as the blades 25 and 26 are fixed, in positions close to the end of the sleeve 22 corresponding to the end 19a of the body of the burner.
  • the sheath 22 is on the other hand fixed on the casing 1 of the drum-dryer-coater, by means of lugs 27 welded to the end of the blades such as 25 and to the interior surface of the casing 1.
  • the blades 25 and 26 are inclined with respect to the longitudinal axis 5 of the drum, at an angle other than 90 °, so that these blades, during the rotation of the drum, constitute a turbine allowing the gases to be sucked out. located in the part of the drum situated between the outlet end 3 of this drum and the end of the burner around which the blades 25, 26 are fixed.
  • the projected surfaces of the blades 25, 26 cover the whole of the straight section of the drum in its central zone corresponding to the flame development zone.
  • the blades 25, 26 thus constitute an anti-radiation screen separating the flame zone from the zone located downstream, around the advanced body 19 of the burner 20.
  • Propeller-shaped vanes 28 are fixed on the internal surface of the casing 1 of the drum, immediately upstream of the blades 25, 26 secured to the sheath 22. These helical vanes 28 ensure the passage of materials from upstream to the downstream side of the turbine constituted by the blades 25, 26.
  • the body 21 of the burner 20 has a relatively large length, so that the end of the burner from which the flame 14 develops is in a position remote from the outlet end 3 of the drum.
  • the zone of the drum into which the burner body penetrates constitutes, in its peripheral part, that is to say between the external sheath 22 and the casing 1, 1a of the drum, the coating zone 30 of the drum in which opens the head 31 of the bitumen injection device.
  • This injection head 31 is located downstream of the end part 19a of the body of the burner 19, that is to say downstream of the blades 25 and 26.
  • the internal surface of the casing 1 of the drum-dryer-coater carries hook blades 32 ensuring a lifting of the materials throughout the section of the drum to produce a efficient mixing of aggregates and bitumen and the production of homogeneous and malleable mixes.
  • a curtain of materials falling over the entire section of the drum is formed immediately downstream of the blades 25, 26 and upstream of the nozzle 31.
  • a nozzle 33 for injecting pulverulent material constituted by an endless screw is also disposed inside the zone 30 and opens into this zone, downstream of the nozzle 31 for injecting bitumen.
  • the pulverulent materials thus come into contact with solid materials covered with bitumen.
  • the pulverulent materials are thus retained by bonding on the aggregates and cannot fly inside the drum. There is therefore a double coating; firstly, the aggregates with a large particle size are coated with bitumen by the nozzle 31. These aggregates contain very few fines since these have been separated and entrained by the gases circulating in the drum, in the drying zone ( 8, 9).
  • the aggregates with a large particle size are coated effectively and the addition of bitumen is carried out in an area which is perfectly isolated from the flame area and in which neither air stream nor water value stream circulates. This prevents oxidation and "steam-cracking" of the bitumen.
  • the fine-grained elements are introduced by the nozzle 33 constituted by an endless screw. These fine elements are poured onto the elements with a large particle size which have been coated in the first part of the zone 30. This prevents any formation of pellets formed by fine elements and bitumen. In addition, the aggregates with large particle sizes coated with bitumen which rain in the first part of the zone 30 make it possible to retain by bonding the fines which would tend to propagate upstream in the drum.
  • an atomizer 35 performing a fractionation of the fuel introduced into the central part of the burner body and an intimate mixture with the combustion air.
  • the casing 1 When the drum-dryer-coater is in service, the casing 1 is rotated about its longitudinal axis 5, which also causes the outer sheath 22 to rotate around the burner 20 and the blades 25 and 26 fixed to the sheath external.
  • These blades constitute blades of a turbine ensuring a certain suction of the gases located in the zone 30 in the direction of the flame zone (arrow 37).
  • the hot gases passing through the drum exit through the inlet end 2 of the casing 1 of the drum and are evacuated by a recovery device 38.
  • the aggregates are raised inside the drum and fall in rain over a large part of the internal cross section of the envelope 1.
  • the cold and wet aggregates are thus exposed to hot gases circulating in the drum, in the extension of the flame 14. This produces an intense drying and heating of the aggregates which is further increased, when the aggregates reach the flame zone 14.
  • the aggregates are taken care of, in this zone , by the anti-radiation vanes 13. (see figure 4).
  • the recycling ring 12 is placed around the casing 1 of the drum which includes chutes 41 for introducing the recycled materials poured into the hopper 42 of the recycling ring 12, in openings passing through the casing 1 of the drum.
  • a second smaller diameter drum 40 is disposed inside the casing 1 of the drum, in the recycling zone.
  • Helical blades 43 are fixed on the second drum 40 for the introduction of recycled materials downstream of the recycling ring behind the anti-radiation vanes 13.
  • the virgin aggregates are also transported downstream of the recycling ring and mixed with recycled asphalt.
  • the flame 14 of the burner is pear-shaped, its diameter gradually increasing from the atomizer 35 to the vicinity of its terminal part. At the recycling ring, the flame therefore occupies only a central part of the drum section. Recycled materials are therefore not exposed directly to the flame when they enter the drum.
  • the coated materials recycled at the recycling ring 12 are incorporated into virgin aggregates which are perfectly dry and brought to a high temperature. A rapid reflow of the bitumen of the recycled materials is thus obtained in the last part of the flame zone 14.
  • the vapors released possibly by the recycled materials are incinerated by means of the annular diaphragm 17 which concentrates the hot gases at the outlet of the combustion zone.
  • the heating of the aggregates is accompanied by intensive drying and the water vapor formed escapes through the openings of the anti-radiation vanes 13. This water vapor is evacuated by the gas stream without coming into contact with the bitumen. new. The mixture is therefore practically dry when it enters zone 30.
  • the virgin aggregates mixed with the reclaimed recycled asphalt are introduced into the zone 30 where liquid bitumen is incorporated into them by the injection nozzle 31.
  • the fins 32 lining the casing of the drum in the zone 30 make it possible to lift the aggregates throughout the section of the drum and to carry out effective kneading and coating of the aggregates brought into contact with the bitumen.
  • the blades 25 and 26 secured to the outer casing movable in rotation around the burner provide effective protection of the materials containing bitumen.
  • the screen effect of the blades 25 and 26 of the burner is increased by the presence of a curtain of materials falling throughout the section of the drum, inside the zone 30.
  • Pulverulent material is incorporated by the nozzle 33 into the aggregates covered with bitumen. This pulverulent material is thus retained by the aggregates thanks to the adhesive power of the bitumen.
  • the coated materials are recovered at the outlet of the drum, at the opening 16.
  • the drying and coating drum according to the invention therefore makes it possible to ensure a good quality coating in a zone perfectly separated from the flame zone of the drum, thanks to a burner of improved design.
  • blades having a shape other than the blades 25, 26 which have been described and that these blades can be arranged in any number around the external sleeve surrounding the burner 20.
  • the blades fixed on the internal surface of the drum may have a shape different from that which has been described and shown.
  • the device according to the invention can be used both for the preparation of bituminous mixes from virgin materials and recycled materials as for the preparation of mixes from virgin materials only.

Abstract

The drying/coating drum comprising a burner (20) whose body (19) penetrates via the discharge end (3) of the drum into a zone which is distant from this end. The gases and the solid materials circulate countercurrent-wise in the drum. The body (19) of the burner (20), fixed relative to the drum (1), is disposed inside an outer peripheral sleeve (22) which is free in rotation about the body (19) of the burner (20). The outer sleeve (22) is connected to the casing (1) of the drum. The end of the outer sleeve (22) corresponding to the end (19a) of the burner from which the flame (14) develops carries a plurality of radially directed blades (25, 26) forming a turbine for sucking gas into the mixing zone (30) and a screen against radiation from the flame (14) of the burner (20) during rotation of the drum.

Description

L'invention concerne un tambour sécheur et enrobeur pour la préparation de produits enrobés bitumineux comportant un brûleur perfectionné.The invention relates to a drying and coating drum for the preparation of bituminous coated products comprising an improved burner.

On connaît des dispositifs pour la préparation de produits enrobés bitumineux à partir d'agrégats et de bitume qui sont constitués par un tambour comportant une enveloppe cylindrique dans laquelle sont effectués le séchage et le chauffage des agrégats introduits par une extrémité du tambour et l'enrobage des agrégats séchés et chauffés par du bitume généralement introduit sous forme liquide.Devices are known for the preparation of bituminous coated products from aggregates and bitumen which are constituted by a drum comprising a cylindrical envelope in which the drying and heating of the aggregates introduced by one end of the drum and the coating are carried out. aggregates dried and heated with bitumen generally introduced in liquid form.

Il est également possible d'introduire une certaine quantité de produits enrobés usagés sous forme concassée dans le tambour, de manière à les incorporer aux agrégats vierges introduits par une extrémité du tambour.It is also possible to introduce a certain quantity of used coated products in crushed form into the drum, so as to incorporate them into the virgin aggregates introduced by one end of the drum.

De manière générale, les tambours-sécheurs-enrobeurs sont garnis intérieurement d'ailettes de relevage ou d'agitation des matériaux et le tambour dont l'axe est légèrement incliné dans le sens allant de son extrémité d'entrée vers son extrémité de sortie assure le transport des matériaux solides, lorsqu'il est mis en rotation autour de son axe longitudinal.In general, the drum-dryers-wrappers are internally lined with lifting or agitating fins for the materials and the drum whose axis is slightly inclined in the direction going from its inlet end to its outlet end ensures the transport of solid materials, when it is rotated about its longitudinal axis.

Les matières solides constituées principalement par les agrégats sont donc mises en circulation suivant la direction longitudinale du tambour et sont successivement séchées et chauffées puis enrobées de bitume.The solid materials mainly constituted by the aggregates are therefore circulated in the longitudinal direction of the drum and are successively dried and heated then coated with bitumen.

La chaleur nécessaire pour effectuer le séchage et le chauffage des agrégats et/ou la refusion des enrobés recyclés est fournie au tambour par un brûleur pénétrant axialement par l'une des extrémités de l'enveloppe.The heat necessary to carry out the drying and heating of the aggregates and / or the reflow of the recycled coated materials is supplied to the drum by a burner penetrating axially through one of the ends of the envelope.

Le brûleur peut être introduit dans l'enveloppe par son extrémité recevant les agrégats vierges, généralement désignée comme extrémité d'entrée. Dans ce cas, les gaz chauds provenant du brûleur et les agrégats circulent dans le même sens à l'intérieur du tambour.The burner can be introduced into the casing by its end receiving the virgin aggregates, generally designated as the inlet end. In this case, the hot gases from the burner and the aggregates circulate in the same direction inside the drum.

Il est également possible d'introduire le brûleur par l'extrémité longitudinale de l'enveloppe du tambour opposée à son extrémité d'entrée et, dans ce cas, les gaz chauds circulent à contre-courant par rapport aux agrégats à l'intérieur de l'enveloppe du tambour (US-A-4 787 938). Cette disposition du brûleur avec circulation à contre-courant des gaz chauds présente des avantages dans le cas où le brûleur comporte un corps de grande longueur disposé axialement dans le tambour, dans la mesure où l'extrémité du corps à partir de laquelle se développe la flamme se trouve dans une zone éloignée de l'extrémité de sortie du tambour.It is also possible to introduce the burner through the longitudinal end of the drum casing opposite its inlet end and, in this case, the hot gases circulate against the current with respect to the aggregates inside the drum shell (US-A-4,787,938). This arrangement of the burner with counter-current circulation of hot gases has advantages in the case where the burner has a very long body disposed axially in the drum, insofar as the end of the body from which the flame is in an area away from the outlet end of the drum.

Le tambour est ainsi globalement séparé en deux zones, à savoir une première zone située entre l'extrémité d'entrée du tambour et l'extrémité du brûleur, dans laquelle se développe la flamme du brûleur et dans laquelle circulent les gaz chauds et une seconde zone située autour du corps du brûleur entre l'extrémité du brûleur et l'extrémité de sortie du tambour, cette seconde zone n'étant pas soumise à la circulation des gaz chauds provenant du brûleur. Cette disposition permet de réaliser le séchage et le chauffage des agrégats dans la première zone et l'enrobage des agrégats séchés et chauffés dans la seconde zone, en diminuant les risques de dégradation et d'inflammation du bitume.The drum is thus generally separated into two zones, namely a first zone located between the inlet end of the drum and the end of the burner, in which the burner flame develops and in which the hot gases circulate and a second area around the burner body between the end of the burner and the outlet end of the drum, this second area not being subject to the circulation of hot gases from the burner. This arrangement makes it possible to carry out the drying and heating of the aggregates in the first zone and the coating of the dried and heated aggregates in the second zone, by reducing the risks of degradation and ignition of the bitumen.

Ces risques sont encore diminués si on dispose un diaphragme dans la section transversale du tambour, pour séparer la zone de flamme de la zone d'enrobage (WO-A-8 802 052). De tels diaphragmes ont cependant l'inconvénient de réduire la section de passage des agrégats dans le tambour ; de plus, ces diaphragmes subissent en service des contraintes et des chocs qui conduisent à leur destruction plus ou moins rapide.These risks are further reduced if there is a diaphragm in the cross section of the drum, to separate the flame zone from the coating zone (WO-A-8 802 052). However, such diaphragms have the drawback of reducing the cross-section of the aggregates in the drum; moreover, these diaphragms undergo stresses and shocks in service which lead to their more or less rapid destruction.

On connaît également un tambour sécheur enrobeur à circulation des gaz à contre-courant des matières solides comportant un ventilateur annexe à fort débit destiné à aspirer les vapeurs de bitume dans la zone d'enrobage. Cette aspiration à grand débit a tendance à favoriser la formation de vapeur et à entraîner des matières pulvérulentes introduites dans le tambour de manière pneumatique vers le brûleur. Celui- ci a donc tendance à s'encrasser.There is also known a coating dryer drum with circulation of gases against the current of solid materials comprising a high-speed auxiliary fan intended to suck the bitumen vapors into the coating zone. This high-flow suction tends to favor the formation of vapor and to entrain pulverulent materials introduced into the drum pneumatically towards the burner. It therefore tends to clog.

Pour éviter d'aspirer de trop grandes quantités de poussière, on utilise une chambre dans laquelle on mélange les matières pulvérulentes avec du bitume. Cependant, on favorise ainsi la formation de vapeur de bitume et de boulettes constituées par un mélange de pulvérulent et de bitume ce qui est très néfaste pour la qualité des enrobés produits. De plus, dans un tel tambour sécheur enrobeur, le malaxage est réalisé en contact avec le fond du tambour, ce qui nuit à la qualité de l'enrobé produit.To avoid sucking too large amounts of dust, a chamber is used in which the pulverulent materials are mixed with bitumen. However, the formation of bitumen vapor and pellets constituted by a mixture of pulverulent and bitumen is thus favored, which is very harmful for the quality of the mixes produced. In addition, in such a coating dryer drum, the mixing is carried out in contact with the bottom of the drum, which affects the quality of the coated product.

Enfin, le ventilateur d'extraction assure le transport de toute la vapeur d'eau contenue dans les recyclés et la fait passer au-dessus du bitume neuf, ce qui favorise la distillation et la vaporisation du bitume par le phénomène de "steam cracking".Finally, the extraction fan ensures the transport of all the water vapor contained in the recycled material and passes it over the new bitumen, which promotes the distillation and vaporization of the bitumen by the "steam cracking" phenomenon. .

Dans le cas de tambours à circulation des gaz à contre-courant par rapport aux matières solides et avec brûleur avancé, on ne connaissait pas jusqu'ici de dispositif efficace, résistant et peu encombrant permettant d'isoler la zone de flamme de la zone d'enrobage et d'évacuer les matières volatiles provenant de l'échauffement du bitume dans la zone d'enrobage.In the case of drums with gas flow against the current with respect to solids and with an advanced burner, an efficient, resistant and space-saving device has not hitherto been known. making it possible to isolate the flame zone from the coating zone and to evacuate the volatile matter originating from the heating of the bitumen in the coating zone.

Le but de l'invention est donc de proposer un tambour sécheur et enrobeur pour la préparation de produits enrobés bitumineux, à partir d'agrégats et de bitume, le tambour ayant une enveloppe de forme cylindrique comportant une première extrémité, ou extrémité d'entrée par laquelle on introduit une partie au moins des agrégats et une seconde extrémité, ou extrémité de sortie, par laquelle le corps d'un brûleur pénètre dans le tambour suivant sa direction axiale jusqu'à une zone éloignée de l'extrémité de sortie, de manière à développer une flamme et à assurer la mise en circulation de gaz chauds suivant la longueur du tambour, dans le sens opposé au sens de circulation des agrégats, à partir de l'extrémité du corps du brûleur, un moyen d'injection de bitume disposé de manière à déboucher dans une zone d'enrobage du tambour située autour du corps du brûleur et des moyens de mise en rotation du tambour autour de son axe, ce tambour sécheur et enrobeur comportant une zone de malaxage autour du corps du brûleur parfaitement isolée de la zone de flamme lorsque le tambour est en service et assurant l'élimination des produits volatils dégagés par le bitume dans la zone de malaxage.The object of the invention is therefore to propose a drying and coating drum for the preparation of bituminous coated products, from aggregates and bitumen, the drum having a cylindrical casing having a first end, or inlet end. by which at least part of the aggregates are introduced and a second end, or outlet end, through which the body of a burner enters the drum in its axial direction to an area remote from the outlet end, so as to develop a flame and ensure the circulation of hot gases along the length of the drum, in the direction opposite to the direction of circulation of the aggregates, from the end of the body of the burner, a means for injecting bitumen disposed in a drum coating zone situated around the body of the burner and means for rotating the drum around its axis, this drying and coating drum eur having a mixing zone around the burner body perfectly isolated from the flame zone when the drum is in service and ensuring the elimination of volatile products released by the bitumen in the mixing zone.

Dans ce but, la partie du corps du brûleur située à l'intérieur du tambour est disposée de manière coaxiale à l'intérieur d'un fourreau externe périphérique, libre en rotation autour du corps du brûleur et relié à l'enveloppe du tambour dont une extrémité correspondant à l'extrémité du brûleur à partir de laquelle se développe la flamme porte une pluralité de pales de direction radiale par rapport à l'enveloppe du tambour ayant des faces inclinées par rapport à la direction longitudinale du tambour et constituant une turbine d'aspiration de gaz dans le sens allant de la seconde vers la première extrémité, pendant la rotation du tambour, et un écran contre le rayonnement de la flamme du brûleur.For this purpose, the part of the burner body located inside the drum is arranged coaxially inside a peripheral external sheath, free to rotate around the burner body and connected to the casing of the drum, one end corresponding to the end of the burner from which the flame develops carries a plurality of blades of radial direction with respect to the casing of the drum having faces inclined with respect to the longitudinal direction of the drum and constituting a gas suction turbine in the direction going from the second to the first end, during the rotation of the drum , and a screen against the radiation from the burner flame.

Afin de bien faire comprendre l'invention, on va maintenant décrire, à titre d'exemple non limitatif, en se référant aux figures jointes en annexe, un mode de réalisation d'un tambour sécheur enrobeur suivant l'invention.In order to clearly understand the invention, a description will now be given, by way of nonlimiting example, with reference to the appended figures, an embodiment of a coating dryer drum according to the invention.

La figure 1 est une vue en coupe axiale de l'ensemble du tambour sécheur enrobeur.Figure 1 is an axial sectional view of the entire coating dryer drum.

La figure 2 est une vue en coupe transversale partielle suivant 2-2 de la figure 1.FIG. 2 is a partial cross-sectional view along 2-2 of FIG. 1.

La figure 3 est une vue en coupe transversale partielle suivant 3-3 de la figure 1.Figure 3 is a partial cross-sectional view along 3-3 of Figure 1.

La figure 4 est une vue en coupe transversale partielle suivant 4-4 de la figure 1.FIG. 4 is a partial cross-sectional view along 4-4 of FIG. 1.

La figure 5 est une vue en coupe transversale partielle suivant 5-5 de la figure 1.FIG. 5 is a partial cross-sectional view along 5-5 of FIG. 1.

La figure 6 est une vue en coupe transversale suivant 6-6 de la figure 1.Figure 6 is a cross-sectional view along 6-6 of Figure 1.

La figure 7 est une vue en coupe transversale suivant 7-7 de la figure 1.Figure 7 is a cross-sectional view along 7-7 of Figure 1.

La figure 8 est une vue en coupe transversale suivant 8-8 de la figure 1.Figure 8 is a cross-sectional view along 8-8 of Figure 1.

Le tambour sécheur enrobeur représenté sur la figure 1 comporte une enveloppe 1 de forme globalement cylindrique comportant une première extrémité 2 constituant son extrémité d'entrée et une seconde extrémité 3 constituant son extrémité de sortie.The coating dryer drum shown in FIG. 1 comprises a casing 1 of generally cylindrical shape comprising a first end 2 constituting its inlet end and a second end 3 constituting its outlet end.

L'enveloppe 1, dans la position de service du tambour, est montée sur une plateforme de manière que son axe longitudinal 5 soit incliné par rapport à l'horizontale, l'extrémité d'entrée 2 étant à un niveau supérieur au niveau de l'extrémité de sortie 3. L'enveloppe 1 est également montée rotative sur la plateforme, autour de son axe longitudinal 5.The casing 1, in the operating position of the drum, is mounted on a platform so that its longitudinal axis 5 is inclined relative to the horizontal, the inlet end 2 being at a level higher than the level of the outlet end 3. The casing 1 is also rotatably mounted on the platform, around its longitudinal axis 5.

La plateforme et les éléments permettant un montage rotatif et un entraînement en rotation de l'enveloppe 1 n'ont pas été représentés, ces éléments étant habituels dans la technique de construction des tambours-sécheurs-enrobeurs.The platform and the elements allowing a rotary mounting and a rotary drive of the casing 1 have not been shown, these elements being usual in the technique of construction of the drum-dryers-coaters.

Par l'extrémité d'entrée 2 du tambour pénètre un dispositif 6 de transport et de déversement d'agrégats qui sont ainsi déversés dans une zone d'introduction 7 dans laquelle la surface intérieure du tambour est garnie par des aubes 7′ en saillie radiale vers l'intérieur et enroulées en hélice sur la surface du tambour.Through the inlet end 2 of the drum penetrates a device 6 for transporting and discharging aggregates which are thus discharged into an introduction zone 7 in which the internal surface of the drum is furnished by vanes 7 'projecting radially inward and helically wound on the surface of the drum.

Les aubes 7′ disposées suivant des hélices permettent d'introduire très rapidement les agrégats dans la seconde zone 8 du tambour.The vanes 7 ′ arranged along helices make it possible to very quickly introduce the aggregates into the second zone 8 of the drum.

Dans cette zone 8, comme il est visible sur la figure 2, l'enveloppe 1 porte sur sa surface interne des aubes plates 10 permettant d'assurer une certaine agitation des agrégats, sans soulèvement de ces agrégats à l'intérieur du tambour.In this zone 8, as can be seen in FIG. 2, the envelope 1 carries on its internal surface flat vanes 10 making it possible to ensure a certain agitation of the aggregates, without lifting these aggregates inside the drum.

A la suite des zones 7 et 8, dans lesquelles les agrégats restent en contact avec la surface interne du tambour, le tambour-sécheur-enrobeur comporte une zone 9 dans laquelle la surface intérieure de l'enveloppe 1 est garnie par des aubes 11 en forme de crochets permettant d'assurer un certain relevage des agrégats à l'intérieur du tambour pendant sa rotation. Cette zone 9 constitue une zone de séchage et de chauffage, les agrégats étant exposés au rayonnement de la flamme et mis en contact avec les gaz chauds en circulation dans le tambour.Following zones 7 and 8, in which the aggregates remain in contact with the internal surface of the drum, the drum-dryer-coater comprises a zone 9 in which the internal surface of the casing 1 is filled with vanes 11 in shape of hooks to ensure a certain lifting of the aggregates inside the drum during its rotation. This zone 9 constitutes a drying and heating zone, the aggregates being exposed to radiation of the flame and brought into contact with the hot gases circulating in the drum.

La zone de séchage et de chauffage 9 occupe une longueur substantielle du tambour et se termine au niveau d'un diaphragme annulaire 17 délimitant la zone dans laquelle se développe la flamme 14 du brûleur. En aval du diaphragme 17, dans la première partie de la zone de flamme, un anneau de recyclage 12 est disposé autour du tambour de manière à permettre l'introduction de matériaux recyclés dans le tambour.The drying and heating zone 9 occupies a substantial length of the drum and ends at an annular diaphragm 17 delimiting the zone in which the flame 14 of the burner develops. Downstream of the diaphragm 17, in the first part of the flame zone, a recycling ring 12 is arranged around the drum so as to allow the introduction of recycled materials into the drum.

Comme il est visible sur la figure 4, la surface interne de l'enveloppe 1 du tambour comporte, dans la zone située entre le diaphragme 17 et l'anneau 12 de recyclage, des aubes anti-rayonnement 13 dont la forme permet de protéger les matériaux introduits dans le tambour contre le rayonnement de la flamme. Les aubes 13 délimitent, avec la surface intérieure de l'enveloppe 1, des poches successives dont la paroi dirigée vers l'intérieur du tambour, c'est-à-dire vers la flamme 14 du brûleur évite une exposition directe des matériaux.As can be seen in FIG. 4, the internal surface of the casing 1 of the drum comprises, in the zone situated between the diaphragm 17 and the recycling ring 12, anti-radiation vanes 13 whose shape makes it possible to protect the materials introduced into the drum against the radiation of the flame. The blades 13 delimit, with the inner surface of the casing 1, successive pockets, the wall of which faces towards the interior of the drum, that is to say towards the flame 14 of the burner, avoids direct exposure of the materials.

La partie 1a de l'enveloppe 1 disposée au voisinage de l'extrémité de sortie 3 présente un diamètre supérieur au diamètre des autres parties de l'enveloppe.Part 1a of the envelope 1 disposed in the vicinity of the outlet end 3 has a diameter greater than the diameter of the other parts of the envelope.

Cette partie 1a est engagée par son extrémité voisine de la section de sortie 3 dans un élément de façade 15 comportant une ouverture de sortie 16 des enrobés élaborés dans le tambour.This part 1a is engaged by its end close to the outlet section 3 in a facade element 15 comprising an outlet opening 16 of the mixes produced in the drum.

Sur la façade 15 est également fixé, dans une position centrale, un support 18 dans lequel est engagé le corps fixe 19 du brûleur 20 pénétrant par l'extrémité du tambour-sécheur-enrobeur.On the front 15 is also fixed, in a central position, a support 18 in which is engaged the fixed body 19 of the burner 20 penetrating through the end of the drum-dryer-coater.

Le corps 19 du brûleur 20 qui est fixe en rotation par rapport à l'enveloppe 1 du tambour pénètre à l'intérieur de l'enveloppe 1 suivant sa direction axiale. La partie du corps 19 située à l'intérieur du tambour est disposée de manière axiale à l'intérieur d'un fourreau externe périphérique 22, libre en rotation autour du corps 19. Le fourreau 22 est monté rotatif à l'intérieur du support 18 par l'intermédiaire de galets 23 et autour du corps 19 du brûleur, par l'intermédiaire de galets 24.The body 19 of the burner 20 which is fixed in rotation relative to the casing 1 of the drum penetrates inside the casing 1 in its axial direction. The part of the body 19 located inside the drum is disposed axially inside a peripheral external sheath 22, free to rotate around the body 19. The sheath 22 is rotatably mounted inside the support 18 by means of rollers 23 and around the body 19 of the burner, by means of rollers 24.

Le combustible et l'air de combustion sont amenés au brûleur par l'intérieur du corps 19 qui comporte une extrémité de sortie 19a à partir de laquelle se développe la flamme 14.The fuel and the combustion air are supplied to the burner through the interior of the body 19 which has an outlet end 19a from which the flame 14 develops.

Sur la surface extérieure du fourreau 22, et dans des directions radiales sont fixées des pales telles que les pales 25 et 26, dans des positions voisines de l'extrémité du fourreau 22 correspondant à l'extrémité 19a du corps du brûleur.On the outer surface of the sleeve 22, and in radial directions, blades such as the blades 25 and 26 are fixed, in positions close to the end of the sleeve 22 corresponding to the end 19a of the body of the burner.

Le fourreau 22 est d'autre part fixé sur l'enveloppe 1 du tambour-sécheur-enrobeur, par l'intermédiaire de pattes 27 soudées à l'extrémité des pales telles que 25 et sur la surface intérieure de l'enveloppe 1.The sheath 22 is on the other hand fixed on the casing 1 of the drum-dryer-coater, by means of lugs 27 welded to the end of the blades such as 25 and to the interior surface of the casing 1.

Les pales 25 et 26 sont inclinées par rapport à l'axe longitudinal 5 du tambour, d'un angle différent de 90°, si bien que ces pales, lors de la rotation du tambour, constituent une turbine permettant d'aspirer les gaz se trouvant dans la partie du tambour située entre l'extrémité de sortie 3 de ce tambour et l'extrémité du brûleur autour de laquelle sont fixées les pales 25, 26.The blades 25 and 26 are inclined with respect to the longitudinal axis 5 of the drum, at an angle other than 90 °, so that these blades, during the rotation of the drum, constitute a turbine allowing the gases to be sucked out. located in the part of the drum situated between the outlet end 3 of this drum and the end of the burner around which the blades 25, 26 are fixed.

Sur la figure 7, on voit que les surfaces projetées des pales 25, 26 couvrent la totalité de la section droite du tambour dans sa zone centrale correspondant à la zone de développement de la flamme. Les pales 25, 26 constituent ainsi un écran anti-rayonnement séparant la zone de flamme de la zone située en aval, autour du corps avancé 19 du brûleur 20.In FIG. 7, it can be seen that the projected surfaces of the blades 25, 26 cover the whole of the straight section of the drum in its central zone corresponding to the flame development zone. The blades 25, 26 thus constitute an anti-radiation screen separating the flame zone from the zone located downstream, around the advanced body 19 of the burner 20.

Des aubes en forme d'hélices 28 sont fixées sur la surface interne de l'enveloppe 1 du tambour, immédiatement en amont des pales 25, 26 solidaires du fourreau 22. Ces aubes en hélice 28 assurent le passage des matériaux de l'amont à l'aval de la turbine constituée par les pales 25, 26.Propeller-shaped vanes 28 are fixed on the internal surface of the casing 1 of the drum, immediately upstream of the blades 25, 26 secured to the sheath 22. These helical vanes 28 ensure the passage of materials from upstream to the downstream side of the turbine constituted by the blades 25, 26.

Le corps 21 du brûleur 20 présente une longueur relativement importante, si bien que l'extrémité du brûleur à partir de laquelle se développe la flamme 14 est dans une position éloignée par rapport à l'extrémité de sortie 3 du tambour. La zone du tambour dans laquelle pénètre le corps du brûleur constitue, dans sa partie périphérique, c'est-à-dire entre le fourreau externe 22 et l'enveloppe 1, 1a du tambour, la zone d'enrobage 30 du tambour dans laquelle débouche la tête 31 du dispositif d'injection de bitume. Cette tête d'injection 31 se trouve située en aval de la partie d'extrémité 19a du corps du brûleur 19, c'est-à-dire en aval des pales 25 et 26.The body 21 of the burner 20 has a relatively large length, so that the end of the burner from which the flame 14 develops is in a position remote from the outlet end 3 of the drum. The zone of the drum into which the burner body penetrates constitutes, in its peripheral part, that is to say between the external sheath 22 and the casing 1, 1a of the drum, the coating zone 30 of the drum in which opens the head 31 of the bitumen injection device. This injection head 31 is located downstream of the end part 19a of the body of the burner 19, that is to say downstream of the blades 25 and 26.

Comme il est visible sur les figures 5 et 8, dans la zone 30, la surface interne de l'enveloppe 1 du tambour-sécheur-enrobeur porte des aubes-crochets 32 assurant un relevage des matériaux dans toute la section du tambour pour réaliser un malaxage efficace des agrégats et du bitume et la production d'enrobés homogènes et malléables. Un rideau de matériaux retombant dans toute la section du tambour est constitué immédiatement en aval des pales 25, 26 et en amont de la buse 31.As can be seen in FIGS. 5 and 8, in zone 30, the internal surface of the casing 1 of the drum-dryer-coater carries hook blades 32 ensuring a lifting of the materials throughout the section of the drum to produce a efficient mixing of aggregates and bitumen and the production of homogeneous and malleable mixes. A curtain of materials falling over the entire section of the drum is formed immediately downstream of the blades 25, 26 and upstream of the nozzle 31.

Une buse 33 d'injection de pulvérulents constituée par une vis sans fin est également disposée à l'intérieur de la zone 30 et débouche dans cette zone, en aval de la buse 31 d'injection de bitume. Les matériaux pulvérulents viennent ainsi en contact avec des matériaux solides recouverts de bitume. Les matériaux pulvérulents sont ainsi retenus par collage sur les agrégats et ne peuvent s'envoler à l'intérieur du tambour. On réalise donc un double enrobage ; dans un premier temps, les agrégats à forte granulométrie sont enrobés de bitume par la buse 31. Ces agrégats renferment très peu de fines puisque celles-ci ont été séparées et entraînées par les gaz en circulation dans le tambour, dans la zone de séchage (8, 9). Les agrégats à forte granulométrie sont enrobés de manière efficace et l'addition de bitume est effectuée dans une zone parfaitement isolée de la zone de flamme et dans laquelle ne circulent ni courant d'air, ni courant de valeur d'eau. On évite ainsi l'oxydation et le "steam-cracking" du bitume.A nozzle 33 for injecting pulverulent material constituted by an endless screw is also disposed inside the zone 30 and opens into this zone, downstream of the nozzle 31 for injecting bitumen. The pulverulent materials thus come into contact with solid materials covered with bitumen. The pulverulent materials are thus retained by bonding on the aggregates and cannot fly inside the drum. There is therefore a double coating; firstly, the aggregates with a large particle size are coated with bitumen by the nozzle 31. These aggregates contain very few fines since these have been separated and entrained by the gases circulating in the drum, in the drying zone ( 8, 9). The aggregates with a large particle size are coated effectively and the addition of bitumen is carried out in an area which is perfectly isolated from the flame area and in which neither air stream nor water value stream circulates. This prevents oxidation and "steam-cracking" of the bitumen.

Les éléments à fine granulométrie sont introduits par la buse 33 constituée par une vis sans fin. Ces éléments fins sont déversés sur les éléments à forte granulométrie qui ont été enrobés dans la première partie de la zone 30. On évite ainsi toute formation de boulettes constituées par des éléments fins et du bitume. De plus, les agrégats à forte granulométrie enrobés de bitume qui tombent en pluie dans la première partie de la zone 30 permettent de retenir par collage les fines qui auraient tendance à se propager vers l'amont, dans le tambour.The fine-grained elements are introduced by the nozzle 33 constituted by an endless screw. These fine elements are poured onto the elements with a large particle size which have been coated in the first part of the zone 30. This prevents any formation of pellets formed by fine elements and bitumen. In addition, the aggregates with large particle sizes coated with bitumen which rain in the first part of the zone 30 make it possible to retain by bonding the fines which would tend to propagate upstream in the drum.

A l'extrémité 19a du corps 19 du brûleur, à partir de laquelle se forme la flamme 14, est disposé un atomiseur 35 réalisant un fractionnement du combustible introduit dans la partie centrale du corps du brûleur et un mélange intime avec l'air de combustion. On obtient ainsi, à la sortie 19a du brûleur, une flamme 14 qui s'étend à l'intérieur du tambour, sur une certaine longueur correspondant à la zone d'introduction des recyclés et à une zone intermédiaire 36 entre la zone de séchage et de chauffage et la zone de malaxage 30.At the end 19a of the body 19 of the burner, from which the flame 14 is formed, is arranged an atomizer 35 performing a fractionation of the fuel introduced into the central part of the burner body and an intimate mixture with the combustion air. There is thus obtained, at the outlet 19a of the burner, a flame 14 which extends inside the drum, over a certain length corresponding to the zone for introducing recycled materials and to an intermediate zone 36 between the drying zone and and the mixing zone 30.

Lorsque le tambour-sécheur-enrobeur est en service, l'enveloppe 1 est mise en rotation autour de son axe longitudinal 5, ce qui entraîne également en rotation le fourreau externe 22 autour du brûleur 20 et les pales 25 et 26 fixées sur le fourreau externe.When the drum-dryer-coater is in service, the casing 1 is rotated about its longitudinal axis 5, which also causes the outer sheath 22 to rotate around the burner 20 and the blades 25 and 26 fixed to the sheath external.

Ces pales constituent des pales d'une turbine assurant une certaine aspiration des gaz situés dans la zone 30 en direction de la zone de flamme (flèche 37).These blades constitute blades of a turbine ensuring a certain suction of the gases located in the zone 30 in the direction of the flame zone (arrow 37).

Les parties volatiles des matières bitumineuses introduites dans la zone 30 et séparées sous l'effet de la chaleur des agrégats pénétrant dans cette zone sont ainsi aspirées par les pales de la turbine 25, 26, mises en circulation et mélangées à la flamme 14 du brûleur et ainsi éliminées par combustion.The volatile parts of the bituminous materials introduced into the zone 30 and separated under the effect of the heat from the aggregates entering this zone are thus sucked by the blades of the turbine 25, 26, put into circulation and mixed with the flame 14 of the burner and thus eliminated by combustion.

Les gaz chauds traversant le tambour sortent par l'extrémité d'entrée 2 de l'enveloppe 1 du tambour et sont évacués par un dispositif de récupération 38.The hot gases passing through the drum exit through the inlet end 2 of the casing 1 of the drum and are evacuated by a recovery device 38.

Le fonctionnement du tambour sécheur et enrobeur suivant l'invention sera décrit ci-après.The operation of the drying and coating drum according to the invention will be described below.

Des agrégats vierges froids et humides sont introduits dans le tambour par le dispositif 6. Ces agrégats déversés dans la zone 7 sont transportés rapidement par les hélices 7′ dans la zone 8 comportant des aubes plates. Les agrégats sont alors ralentis et transportés à vitesse plus lente en direction de la zone de séchage 9.Cold and wet virgin aggregates are introduced into the drum by the device 6. These aggregates poured into zone 7 are transported rapidly by the propellers 7 ′ in zone 8 comprising flat blades. The aggregates are then slowed down and transported at a slower speed towards the drying zone 9.

Dans la zone de séchage et de chauffage 9, les agrégats sont soulevés à l'intérieur du tambour et retombent en pluie sur une grande partie de la section transversale interne de l'enveloppe 1. Les agrégats froids et humides sont ainsi exposés aux gaz chauds circulant dans le tambour, dans le prolongement de la flamme 14. On effectue ainsi un séchage et un chauffage intense des agrégats qui est encore accru, lorsque les agrégats parviennent dans la zone de flamme 14. Les agrégats sont pris en charge, dans cette zone, par les aubes anti-rayonnement 13. (voir figure 4).In the drying and heating zone 9, the aggregates are raised inside the drum and fall in rain over a large part of the internal cross section of the envelope 1. The cold and wet aggregates are thus exposed to hot gases circulating in the drum, in the extension of the flame 14. This produces an intense drying and heating of the aggregates which is further increased, when the aggregates reach the flame zone 14. The aggregates are taken care of, in this zone , by the anti-radiation vanes 13. (see figure 4).

Comme il est visible sur la figure 6, l'anneau de recyclage 12 est placé autour de l'enveloppe 1 du tambour qui comporte des goulottes 41 d'introduction des matériaux recyclés déversés dans la trémie 42 de l'anneau de recyclage 12, dans des ouvertures traversant l'enveloppe 1 du tambour. Un second tambour 40 à plus faible diamètre est disposé à l'intérieur de l'enveloppe 1 du tambour, dans la zone de recyclage. Des aubes en hélice 43 sont fixées sur le second tambour 40 pour l'introduction des matériaux recyclés à l'aval de l'anneau de recyclage derrière les aubes anti-rayonnement 13. Les agrégats vierges sont également transportés à l'aval de l'anneau de recyclage et mélangés aux enrobés recyclés.As it can be seen in FIG. 6, the recycling ring 12 is placed around the casing 1 of the drum which includes chutes 41 for introducing the recycled materials poured into the hopper 42 of the recycling ring 12, in openings passing through the casing 1 of the drum. A second smaller diameter drum 40 is disposed inside the casing 1 of the drum, in the recycling zone. Helical blades 43 are fixed on the second drum 40 for the introduction of recycled materials downstream of the recycling ring behind the anti-radiation vanes 13. The virgin aggregates are also transported downstream of the recycling ring and mixed with recycled asphalt.

La flamme 14 du brûleur est en forme de poire, son diamètre augmentant progressivement depuis l'atomiseur 35 jusqu'au voisinage de sa partie terminale. Au niveau de l'anneau de recyclage, la flamme n'occupe donc qu'une partie centrale de la section du tambour. Les matériaux recyclés ne sont donc pas exposés directement à la flamme, à leur entrée dans le tambour.The flame 14 of the burner is pear-shaped, its diameter gradually increasing from the atomizer 35 to the vicinity of its terminal part. At the recycling ring, the flame therefore occupies only a central part of the drum section. Recycled materials are therefore not exposed directly to the flame when they enter the drum.

Les matériaux enrobés recyclés au niveau de l'anneau de recyclage 12 sont incorporés à des agrégats vierges parfaitement secs et portés à une température élevée. On obtient ainsi une refusion rapide du bitume des matériaux recyclés dans la dernière partie de la zone de flamme 14. De plus, les vapeurs dégagées éventuellement par les matériaux recyclés sont incinérées grâce au diaphragme annulaire 17 qui concentre les gaz chauds à la sortie de la zone de combustion.The coated materials recycled at the recycling ring 12 are incorporated into virgin aggregates which are perfectly dry and brought to a high temperature. A rapid reflow of the bitumen of the recycled materials is thus obtained in the last part of the flame zone 14. In addition, the vapors released possibly by the recycled materials are incinerated by means of the annular diaphragm 17 which concentrates the hot gases at the outlet of the combustion zone.

Le chauffage des agrégats s'accompagne d'un séchage intensif et la vapeur d'eau formée s'échappe par les ouvertures des aubes anti-rayonnement 13. Cette vapeur d'eau est évacuée par le courant gazeux sans entrer en contact avec le bitume neuf. Le mélange est donc pratiquement sec, lorsqu'il pénètre dans la zone 30.The heating of the aggregates is accompanied by intensive drying and the water vapor formed escapes through the openings of the anti-radiation vanes 13. This water vapor is evacuated by the gas stream without coming into contact with the bitumen. new. The mixture is therefore practically dry when it enters zone 30.

Les agrégats vierges mélangés aux enrobés recyclés refondus sont introduits dans la zone 30 où du bitume liquide leur est incorporé par la buse d'injection 31.The virgin aggregates mixed with the reclaimed recycled asphalt are introduced into the zone 30 where liquid bitumen is incorporated into them by the injection nozzle 31.

Les ailettes 32 garnissant l'enveloppe du tambour dans la zone 30 permettent de soulever les agrégats dans toute la section du tambour et de réaliser un malaxage et un enrobage efficace des agrégats mis en contact avec le bitume.The fins 32 lining the casing of the drum in the zone 30 make it possible to lift the aggregates throughout the section of the drum and to carry out effective kneading and coating of the aggregates brought into contact with the bitumen.

En outre, lors de la rotation du tambour, les pales 25 et 26 solidaires du fourreau externe mobile en rotation autour du brûleur assurent une protection efficace des matériaux renfermant du bitume.In addition, during the rotation of the drum, the blades 25 and 26 secured to the outer casing movable in rotation around the burner provide effective protection of the materials containing bitumen.

Les fractions volatiles séparées du bitume sous l'effet de la chaleur des agrégats sont aspirées au niveau des pales 25 et 26 inclinées par rapport à l'axe du tambour et renvoyées dans la zone de flamme.The volatile fractions separated from the bitumen under the effect of the heat of the aggregates are sucked at the blades 25 and 26 inclined with respect to the axis of the drum and returned to the flame zone.

L'effet d'écran des pales 25 et 26 du brûleur est accru par la présence d'un rideau de matériaux tombant dans toute la section du tambour, à l'intérieur de la zone 30.The screen effect of the blades 25 and 26 of the burner is increased by the presence of a curtain of materials falling throughout the section of the drum, inside the zone 30.

Du matériau pulvérulent est incorporé par la buse 33 aux agrégats recouverts de bitume. Ce matériau pulvérulent est ainsi retenu par les agrégats grâce au pouvoir adhésif du bitume.Pulverulent material is incorporated by the nozzle 33 into the aggregates covered with bitumen. This pulverulent material is thus retained by the aggregates thanks to the adhesive power of the bitumen.

Le malaxage et l'enrobage se poursuivent tout au long de la zone 30 parfaitement séparée de la zone de flamme. Il ne se produit donc pas de dégradation du bitume et l'enrobage se produit en conséquence dans des conditions satisfaisantes.Mixing and coating continues throughout the zone 30 perfectly separated from the flame zone. There is therefore no degradation of the bitumen and the coating takes place accordingly under satisfactory conditions.

Les enrobés sont récupérés à la sortie du tambour, au niveau de l'ouverture 16.The coated materials are recovered at the outlet of the drum, at the opening 16.

Le tambour sécheur et enrobeur suivant l'invention permet donc d'assurer un enrobage de bonne qualité dans une zone parfaitement séparée de la zone de flamme du tambour, grâce à un brûleur de conception perfectionnée.The drying and coating drum according to the invention therefore makes it possible to ensure a good quality coating in a zone perfectly separated from the flame zone of the drum, thanks to a burner of improved design.

L'invention ne se limite pas au mode de réalisation qui a été décrit.The invention is not limited to the embodiment which has been described.

C'est ainsi qu'on peut imaginer des pales ayant une autre forme que les pales 25, 26 qui ont été décrites et que ces pales peuvent être disposées en un nombre quelconque autour du fourreau externe entourant le brûleur 20. Les aubes fixées sur la surface interne du tambour peuvent avoir une forme différente de celle qui a été décrite et représentée.It is thus possible to imagine blades having a shape other than the blades 25, 26 which have been described and that these blades can be arranged in any number around the external sleeve surrounding the burner 20. The blades fixed on the internal surface of the drum may have a shape different from that which has been described and shown.

Le dispositif suivant l'invention peut être utilisé aussi bien pour la préparation d'enrobés bitumineux à partir de matériaux vierges et de matériaux recyclés que pour la préparation d'enrobés à partir de matériaux vierges uniquement.The device according to the invention can be used both for the preparation of bituminous mixes from virgin materials and recycled materials as for the preparation of mixes from virgin materials only.

Claims (9)

1. Drying and coating drum for the preparation of coated bituminous products from aggregates and bitumen, the drum exhibiting a cylindrical casing (1) provided with a first end (2) or inlet end, through which at least some of the aggregates are introduced, and a second end (3) or outlet end, through which the body (19) of a burner (20) penetrates the drum, in its axial direction, as far as an area separate from the outlet end (3), so that a flame (14) is developed, thereby ensuring that hot gases are put into circulation along the length of the drum, in the opposite direction to the direction of circulation of the aggregates, from the end (19a) of the body (19) of the bu9rner, a means of injecting bitumen (31), arranged so that it opens into a coating area (30) of the drum located around the body (19) of the burner (20), and means of rotating the drum about its axis (5), characterised in that the section of the body (19) of the burner (20) located inside the drum is arranged coaxially inside an outer peripheral lining (22) which is free to rotate about the body (19) of the burner, and connected to the casing (1) of the drum, one end of which, corresponding to the end (19a) of the burner (20), from which the flame (14) develops, supports a plurality of blades (25, 26) extending in the radial direction in relation to the casing (1) of the drum, having faces inclined in relation to the longitudinal direction (5) of the drum, and consituting a gas inlet turbine in the direction running from the second to the firet end of the drum during the rotation of the drum, and a screen protecting against radiation from the flame (14) of the burner (20).
2. Drum according to claim 1, characterised in that the projected surface of the blades (25, 26), in a cross-sectional plane of the drum, is essentially identical to the cross-section of the flame (14) of the burner in its area of largest section.
3. Drum according to claim 1, characterised in that the outer lining (22) surrounding the burner (20) is secured to the casing (1) of the drum by means of at least one blade (25).
4. Drum according to either of claims 1 and 2, characterised in that the outer ring (22) of the burner (20) is rotarily secured to the inside of a fixed element (15) by means of rollers (23) and around the body (19) of the burner by means of rollers (24).
5. Drum according to any of claims 1 to 4, characterised in that it is provided with blades (32) secured to the inner surface of casing (1a), in the coating area (30) located around the burner, ereby guarantesing the removal of solid materials in circulation throughout the cross-section of the drum.
6. Drum according to any of claims 1 to 5, characterised in that it is provided with a drying area (8, 9) between its inlet end (2) and the area in which the flame (14) develops, this drying area being separated from the flame area by an annular diaphragm (17).
7. Drum according to claim 6, characterised in that it is provided with ha ring (12) for introducing recycled materials, located between the drying area (8, 9) and the end (19a) of the burner (20) from which the flame (14) is formed.
8. Drum according to claim 7, characterised in that it comprises anti-radiation blades secured to the inner surface of its casing (1), in the flame area, between the diaphragm (17) and the end of the burner (20) around which are arranged the blades (25, 26) of the turbine, which anti-radiation blades enable the solid materials circulating in the drum to be conveyed and protects these materials against the radiation from the flame.
9. Drum according to any of claims 1 to 8, characterised in that it comprises a device (33) for the introduction of powdery materials present inside the area located around the body (19) of the burner (20), downstream from the means of bitumen injection (31).
EP90400821A 1989-04-05 1990-03-26 Drying and mixing drum with a burner for the preparation of bitumen coated products Expired - Lifetime EP0391768B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT90400821T ATE79141T1 (en) 1989-04-05 1990-03-26 DRUM DRYER AND MIXER WITH BURNER FOR PROCESSING BITUMEN-COATED MATERIALS.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8904475 1989-04-05
FR8904475A FR2645556B1 (en) 1989-04-05 1989-04-05 DRYER AND DRYER FOR THE PREPARATION OF BITUMINOUS COATED PRODUCTS COMPRISING AN IMPROVED BURNER

Publications (2)

Publication Number Publication Date
EP0391768A1 EP0391768A1 (en) 1990-10-10
EP0391768B1 true EP0391768B1 (en) 1992-08-05

Family

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EP90400821A Expired - Lifetime EP0391768B1 (en) 1989-04-05 1990-03-26 Drying and mixing drum with a burner for the preparation of bitumen coated products

Country Status (8)

Country Link
US (1) US4988207A (en)
EP (1) EP0391768B1 (en)
JP (1) JPH0363302A (en)
AT (1) ATE79141T1 (en)
CA (1) CA2013267A1 (en)
DE (1) DE69000242T2 (en)
ES (1) ES2034827T3 (en)
FR (1) FR2645556B1 (en)

Cited By (1)

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Publication number Priority date Publication date Assignee Title
US5538340A (en) 1993-12-14 1996-07-23 Gencor Industries, Inc. Counterflow drum mixer for making asphaltic concrete and methods of operation

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US5203693A (en) * 1991-10-01 1993-04-20 Astec Industries, Inc. Rotary drum dryer having internal flights
US5664881A (en) * 1993-11-16 1997-09-09 Maxam Equipment, Inc. Counter-flow asphalt plant with multi-stage combustion zone overlapping the mixing zone
US5364182A (en) * 1993-11-16 1994-11-15 Michael Hawkins Counter-flow asphalt plant with multi-stage combustion zone overlapping the mixing zone
DE69314647T2 (en) * 1993-11-17 1998-02-12 Giorgio Ghirardelli Plant for the preparation of a bitumen conglomerate in a continuous process
US5772317A (en) * 1996-08-27 1998-06-30 Gencor Industries, Inc. Counterflow drum mixer for making asphaltic concrete and methods of operation
US6267493B1 (en) 1999-06-02 2001-07-31 Cmi Corporation Drum mixer having a plurality of isolated aggregate transport channels
US6672751B2 (en) 2001-01-18 2004-01-06 Michael R. Hawkins Counter-flow asphalt plant with combustion zone feed and exhaust gas heater
US7357562B2 (en) * 2003-03-11 2008-04-15 Hawkins Michael R Counter-flow drum mixer asphalt plant with two stage mixing zone
KR100624345B1 (en) * 2004-07-20 2006-09-19 태성개발(주) Reproduction method of waste asphalt concrete and it's apparatus
JP4859475B2 (en) * 2006-02-15 2012-01-25 株式会社安田製作所 Asphalt waste material recycling equipment
FR2956125B1 (en) * 2010-02-11 2012-03-16 Famaro INSTALLATION FOR THE PRODUCTION OF BITUMINOUS COATED PRODUCTS.
IT1399864B1 (en) * 2010-05-07 2013-05-09 Visani DRYER CYLINDER FOR INCOMBUSIOUS SMOKE REDUCTION
WO2013064851A1 (en) * 2011-11-03 2013-05-10 Visani Roberto Drying cylinder for blasting of the unburnt smokes

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US2421345A (en) * 1944-11-04 1947-05-27 Kenneth E Mcconnaughay Mixer
US3329131A (en) * 1964-12-14 1967-07-04 Space Conditioning Inc Fuel burner and combination thereof with a fire tube boiler
FR2327048A1 (en) * 1975-10-08 1977-05-06 Creusot Loire DEVICE FOR THE PREPARATION OF PRODUCTS MAINLY USED FOR THE CONSTRUCTION AND MAINTENANCE OF ROADS
US4787938B3 (en) * 1986-06-30 1999-11-30 Standard Havens Countercurrent drum mixer asphalt plant
WO1988008052A1 (en) * 1987-04-16 1988-10-20 Marini S.P.A. Asphaltic concrete production apparatus

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5538340A (en) 1993-12-14 1996-07-23 Gencor Industries, Inc. Counterflow drum mixer for making asphaltic concrete and methods of operation

Also Published As

Publication number Publication date
JPH0363302A (en) 1991-03-19
ES2034827T3 (en) 1993-04-01
DE69000242T2 (en) 1993-04-01
DE69000242D1 (en) 1992-09-10
US4988207A (en) 1991-01-29
ATE79141T1 (en) 1992-08-15
EP0391768A1 (en) 1990-10-10
FR2645556A1 (en) 1990-10-12
CA2013267A1 (en) 1990-10-05
FR2645556B1 (en) 1991-07-19

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