The present invention relates to a plant for the production of mixtures in the form of conglomerates with bituminous and non-bituminous binders provided with a dryer. The invention finds useful although not exclusive application in the production of bituminous conglomerates, in particular for road paving.

Prior art

In the field of the production of mixtures in the form of conglomerates with bituminous and non-bituminous binders it is known to use a dryer for eliminating humidity from the conglomerates before their mixing with the binders to obtain the mixture in the form of conglomerates with binders, for example to obtain bituminous conglomerate, that is to say, a ready-to-use bituminous mixture, in particular for road paving.

It is also known to use reclaimed asphalt pavement, or RAP, which consists of bituminous conglomerate deriving from the milling of road pavements to be renovated and that is mixed in the plant for the production of new asphalt or bituminous conglomerate for the purpose of allowing the recycling of the reclaimed material.

The solution that represents the state of the art in the use of reclaimed material consists of a plant with a first drum on the ground for virgin aggregates or conglomerates combined with a second drum for the recycled or reclaimed material, which is placed in a parallel position with respect to the first drum.

The first drum is provided with a respective first burner for obtaining the drying of the virgin aggregates or conglomerates which are dried by means of the exposure to the flame of the first burner. The first drum and respective first burner assembly constitutes a first dryer for virgin aggregates or conglomerates.

The second drum for the reclaimed or recycled material is heated with the input of hot air. By the heating with hot air one avoids the contact between the flame of the second burner and the reclaimed or recycled material, limiting the heating of the

reclaimed or recycled material to temperatures of the order of 160°C. This allows to produce asphalt at the final temperature using only recycled material. The production of hot air occurs through a second burner with a corresponding dedicated combustion chamber from which hot air at a temperature higher than 550-600°C exits in order to obtain a better control of stack emissions. The second drum and respective second burner assembly constitutes a second dryer for reclaimed or recycled material.

In this solution of a plant provided with a first dryer for virgin aggregates or conglomerates and a second dryer for recycled or reclaimed material, the dryers are placed above the mixer so as to avoid jams of heated recycled material in the feeding chutes of the material and between the dryer and the mixer there are containment hoppers. The traditional line of a plant with sieve and hoppers is placed parallel to the dryer and the material is conveyed in the sieve through specific elevators and then in the mixer through a suitable chute. In this type of plants one tries to have as few deviations of the recycled or reclaimed material as possible to avoid problems of jamming of the latter, while preferring to use deviators only for virgin aggregates or conglomerates.

In the prior art solutions the plant is thus provided with two burners that work in the two different dryers.

In the case of the first dryer for virgin aggregates or conglomerates, the first burner has a rated power of the order of 20 MW, for example between 13 and 24 MW depending on production and on the humidity present in the material to be treated.

In the case of the second dryer for recycled or reclaimed material, the second burner has a rated power of the order of 13 MW, for example between 9 and 13 MW depending on production and on the humidity present in the material to be treated. Patent EP0362199, in the name of the same applicant, describes an apparatus for the production of bituminous conglomerate using a rotatable drying and mixing drum having a flow of combustion gas in countercurrent which is generated by means of a burner placed downstream with respect to the direction of advancement of the material to be dried. The drum is provided with means for advancing, drying, impregnating and mixing the material with bituminous substances and fillers. The drum is divided into multiple chambers communicating with each other. The burner is provided with a respective nozzle that generates a flame in a combustion chamber.

Patent application US-4,522,498 describes an apparatus for recycling bituminous conglomerate comprising an elongated rotating drum in which the composition is introduced in a first end and recovered in the opposite second end, and having a burner which extends in the drum in such a way that the nozzle of the burner is located inside the drum in an intermediate position between the first and the second end and directs the hot gases towards the first end.

Patent WO 2016/078755, in the name of the same applicant and incorporated herein as reference, describes a dryer for a plant for the production and distribution of bituminous conglomerates comprising a suction system of air from the dryer and further provided with connecting means to a damping system of polluting compounds that are generated in the plant, wherein the damping system of polluting compounds comprises generation means of an airflow containing said polluting compounds which are drawn from different positions of the plant and are introduced in the airflow containing the polluting compounds in such a way that the polluting compounds are introduced into the dryer whose flame causes a combustion of the polluting compounds generated in the plant.

Application US 4,298,287 describes a plant for the production of asphalt, which is provided with a continuous drum mixer in which the dust is exhausted from an intermediate zone of the drum mixer between its drying and mixing zones. The dust is exhausted radially through openings into a collection housing, which communicates with a dust collector and exhaust blower. An end housing at the discharge end of the drum communicates with the same dust collector and blower. Dampers are provided to control the relative proportion of air exhausted from the drum through the respective housings. Aggregate deflectors on the interior wall of the drum at the intermediate zone allow air and dust to flow while inhibiting the flow of aggregate. The collection housing surrounding the intermediate zone is of a size such as to produce a reduction in the velocity of the air as it passes out of the drum. Consequently, it serves as a knock-out box for the collection of larger particles which are carried out of the drum, but which settle out of the air stream as a result of the velocity decrease. These collected particles are reintroduced into the drum by scoops on the exterior of the drum. These scoops are also used for the introduction of recycled asphaltic concrete.

Application EP0641886 describes a drum for heating rock material and granular recycled asphalt having an inlet and outlet chute for the rock material and the recycled asphalt and a burner at one drum end. A large quantity of granular recycled asphalt is to be heated and added to the new rock material. The solution provides that the inlet chute for the recycled asphalt is arranged at the other drum end remote from the burner, that the outlet chute for the heated recycled asphalt is approximately arranged in the middle of the drum, that the inlet chute for the rock material is arranged after the outlet chute for the heated recycled asphalt towards the burner end of the drum and that the outlet chute for the heated rock material is arranged at the burner end of the drum.

Problems of the prior art

The prior art solutions based on the use of two dryers, each of which is provided with a respective burner, have high operating rated powers because the presence of the two burners easily leads to the exceedance of the power limits set by the regulations above which specific authorizations for the installation of the plant are required.

With particular reference to EP0641886, despite providing a single burner, this patent application is subject to problems with reference to the fact that it does not provide or suggest the possibility to manage the temperature of the hot air flows through the two dyers.

Furthermore the use of high power plants involves greater problems as to the polluting emissions, which are high, having to provide suitable emission damping systems dimensioned on the high rated powers of operation of the plant.

Aim of the invention

The aim of the present invention is to provide a dryer and a plant that guarantee a reduction in the employed rated power and reduced maintenance.

Concept of the invention

The aim is achieved by the characteristics of the main claim. The sub-claims represent advantageous solutions.

Advantageous effects of the invention

The solution according to the present invention, by the considerable creative contribution the effect of which constitutes an immediate and important technical progress, has various advantages.

The solution according to the present invention allows to reduce the rated power of the plant, facilitating the installation of plants according to simpler and faster authorization procedures.

The solution according to the present invention also allows to save energy in the phases of production and operation of the plant.

The solution according to the present invention also allows to reduce the release of polluting compounds into the environment during the production of mixtures in the form of conglomerates with bituminous and non-bituminous binders.

The solution according to the present invention also allows to make more compact plants reducing the occupied surface.

The solution according to the present invention also allows to use recycled materials in a flexible mode with used percentages in the final mixture of the final product which can be in the range 0 to 100%.

Furthermore, with the present invention it is allowed to provide plants with a reduced nominal used power, with a hi capacity of use of recycled materials and with reduced maintenance.

The solution according to the present invention also allows to reduce the phenomena of jamming of the material, making the plant more efficient.

Furthermore the plant integrating the solution according to the invention also allows to obtain further advantages with regard to the reduced maintenance thereof, making the plant more efficient and reducing operating costs.

The solution according to the invention, moreover, is more cost-effective due to:

- the simplification of the heat generation parts;

- the simplification of the structures for supporting the various components;

- the elimination of the direct compartment under the sieve, by direct compartment meaning a hopper that collects the material coming from the dryer, normally containing recycled material, without passing for the sieve.

Description of the drawings

In the following a solution is described with reference to the enclosed drawings, which are to be considered as a non-exhaustive example of the present invention in which: Fig. 1 represents a possible embodiment of a plant in accordance with the present invention.

Fig. 2 represents a detail of an upper part of the plant of Fig. 1.

Fig. 3 represents a front view of an upper part of the plant of Fig. 1.

Fig. 4 represents a side view of an upper part of the plant of Fig. 1.

Fig. 5 represents a detail of an intermediate part of the plant of Fig. 1.

Fig. 6 schematically represents the devices present in the plant of Fig. 1.

Fig. 7 schematically represents a side view partially in section of an upper part of the plant of Fig. 1.

Fig. 8 shows one of the operating modes of a plant in accordance with the present invention.

Fig. 9 shows another of the operating modes of a plant in accordance with the present invention.

Fig. 10 shows still another of the operating modes of a plant in accordance with the present invention.

Fig. 11 shows the airflows inside a part of the dryer in accordance with the present invention.

Description of the invention

With reference to the figures (Fig. 1 , Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7), the present invention applies, in general, to a plant (1 ) for the heat preparation of mixtures in the form of conglomerates with bituminous and non-bituminous binders consisting of:

- inert materials, preferably inert lithic materials, generally gravel, of varied granulometry;

- binder, preferably bitumen, which acts as a binder of the formed mixture;

- possible recycled materials, such as reclaimed asphalt pavement, or RAP, which consists of bituminous conglomerate deriving from the milling of road pavements to be renovated.

The invention finds useful, although not exclusive, application in the production of bituminous conglomerate, in particular for road paving.

The plant (1) operates according to a production cycle that occurs by means of the synchronization of a series of phases and intermediate operations. The production cycle starts with a phase of selection and feeding of the inert lithic materials. A mechanical means, generally a mechanical shovel, collects the inert lithic materials from heaps of non-selected material. The inert lithic materials are stored in different first deposit means, not shown, according to the different granulometry. For example there can be first deposit means that are distinct for inert lithic materials of small granulometry, for inert lithic materials of medium-sized granulometry, for inert lithic materials of large-sized granulometry. In this way it is possible to perform a selective feeding on the basis of the granulometry of the inert lithic materials, which can thus be sent selectively, by means of suitable pre-proportioning devices of the inert lithic materials which then supply the plant by means of conveyor means, such as extraction belts known in the art. The inert lithic materials are then subjected in the plant (1) to the following operating phases of the process, in particular a first operating phase of drying that is carried out in a dryer (4), as explained in the following of the present description. The production cycle ends with the loading of the conglomerate (Fig. 1 , Fig. 6) on

trucks (7) for transport. The first deposit means can be provided with suitable pre-proportioning devices for sending directly the inert lithic materials of different granulometry in the provided and correct quantities towards the devices that are located downstream with respect to the direction of advancement of the material. The first deposit means are preferably made in the form of silos or hoppers open on the upper part to enable loading and closed with openable closing means in correspondence of the bottom which is intended to allow the release of the inert lithic materials on the respective conveyor means of the inert materials which, in their turn, supply a first elevator (8) or elevator of inert materials, preferably but not necessarily in the form of a bucket elevator. It will be clear to those skilled in the art that as an alternative one can use elevators in the form of conveyor belts. In order to enable a continuous supply without interruptions of the production process, the hourly capacity of each of the first deposit means is proportional to the speed of the conveyor means or extraction belts that supply the first elevator (8) or elevator of inert materials.

For the preparation of the mixtures in the form of bituminous conglomerates, in addition to the inert lithic materials, one can also use recycled conglomerates, which are contained within second deposit means, not shown, provided with a pre-proportioning device specific for this type of material. The recycled conglomerate for example may consist of recycled asphalt products. The recycled conglomerate coming from the second deposit means, once dispensed by the pre-proportioning device can be sent to the dryer (4) by means of a second elevator (12) or elevator of inert materials to be used as heat recycled material, or can be sent directly downstream with respect to the dryer (4) to be used as cold recycled material. As an alternative, in one embodiment, in the case of the production that provides the use of cold recycled material, one can also use the plant (1) passing unheated material in the dryer, inserted in a dedicated deposit hopper for the cold recycled material.

In the case in which the recycled conglomerate is not previously divided on the basis of the granulometry, the plant (1) will have to also provide a specific sieve and a mill for reducing the size before the introduction into the plant. As an alternative, the recycled conglomerates can be previously divided on the basis of the granulometry and stored in different second deposit means, each of which is intended for a different granulometry. A control unit (18) of the production cycle automatically carries out the adjustment of capacity of each of the first deposit means and of any one or more second deposit means.

The inert lithic materials and the recycled conglomerates, if present, are sent, by means of the first elevator (8) or elevator of inert materials and the second elevator (12) or elevator of inert materials respectively, towards (Fig. 1 , Fig. 6) the dryer (4) where they are heated to eliminate their humidity in a drying

operating phase. The removal of humidity facilitates the coating of inert lithic materials and recycled conglomerates, if present, with the binder, i. e. bitumen. To this purpose the dryer (4) is provided (Fig. 1 , Fig. 6) with a burner (5), whose operation will be explained in the following of the present description. For a regular operation of the burner (5) it is necessary to opportunely adjust a first suction system (16) of the gases produced in the dryer (4) following the combustion by the burner (5). During the drying phase the fine particles are sucked from the dryer (4) by means of the first suction system (16).

The gases produced in the dryer (4) that come out of the dryer (4) are initially conveyed in a pre-separation device (20) provided with a pre-separation compartment in which the largest particles fall to the base of the compartment and are reintroduced in the production cycle, through a reintroduction device, such as one or more cochlea devices (17', 17"), in correspondence of an outlet of the dryer (4) which is the outlet of the recycled materials or RAP or recycled conglomerates or towards the zone of passage of the outlet of the sifted inert lithic materials. The purpose of said pre-separation device is to reinsert in the process some materials necessary to obtain the correct granulometric curve and, in case of use of RAP, to reduce the harmful emissions. In fact, such larger particles contain bitumen and, by holding back the gases or fumes in the pre-separation device (20), they can be advantageously separated from the finer

particles and, afterwards, reintroduced in the production cycle without harmful releases into the environment.

The gases or fumes that come out of the dryer (4) and that crossed the pre-separation device (20) are then sent (Fig. 1 , Fig. 6) to a filter (6) by means of a first suction connection (30). In the dedusting filter (6) the fine dusts are damped and recovered in a filtering phase before the sucked and filtered air is released by means of fume evacuation means (15). The fine dusts are recovered in a hopper (19) positioned under the filter (6). The fine dusts recovered in the hopper (19) are weighed and proportioned prior to their use by means of (Fig. 1 , Fig. 6) second weighing means (13) of fine dusts. Some formulations of mixtures in the form of bituminous conglomerates also contain, in addition to the previously described inert lithic materials and any recycled conglomerates, a given amount of fine filling material or filler. Its function consists in filling the remaining spaces between the various granulometries of inert lithic materials and recycled conglomerates. The fine filling material to be added is stored in suitable third deposit means or deposits of the filler (29). The fine filling material is taken to the level of the weighing machines by means of a third elevator (42) for fine filling material or filler, which is then weighed and proportioned prior to its use.

After crossing the dryer (4) the inert lithic materials are sent to a mixer (14) where the process for obtaining the bituminous conglomerates continues. At the outlet the dryer (4) the granulometries of the introduced inert lithic materials are mixed with each other. Sometimes it is appropriate, in order to improve their proportion, to carry out a phase of further selection of the latter with separation on the basis of the respective granulometries. To this purpose the inert lithic materials are introduced (Fig. 1 , Fig. 6) in a sieve (9) that divides the inert lithic materials according to the provided sizes in a re-selection phase. Advantageously in the solution of a plant (1) according to the invention the sieve (9) is placed directly below the dryer (4) in such a way that the inert lithic materials are sent to the gravity sieve without the need to resort to further elevators or means of transport with the advantage of avoiding heat losses.

The re-selected inert lithic materials are then stored in optional buffer means, preferably in the form of buffer hoppers under the sieve (10). The buffer means, preferably a series of buffer hoppers under the sieve (10), consisting of different buffer hoppers each of which is associated with a different granulometry range, interrupt the material flow, that up to that point occurs preferably without

interruptions. Each of the buffer hoppers under the sieve (10) is provided with a suitable discharge opening. The discharge openings of the buffer hoppers under the sieve (10) discharge by gravity the re-selected inert lithic materials implementing a proportioning phase in which the various granulometries are proportioned by means of third weighing means (24), preferably in the form of a weighing hopper of inert lithic materials. The third weighing means (24) or weighing hopper of inert lithic materials are placed directly under the buffer hoppers under the sieve (10).

For example the various granulometries can be introduced in sequence one after the other in third weighing means (24) made in the form of a weighing hopper suspended over loading cells carrying out a phase of proportioning based on the sum of the weighs. The feeding of the various granulometries occurs depending on the different productive formulations that one can implement. The third weighing means (24) or weighing hopper of inert lithic materials are connected to the mixer (14) by means of an exhaust (31 ), preferably in the form of a chute.

Meanwhile the fine dusts, previously separated by means of the dedusting filter (6) and accumulated in the hopper (19), are sent (Fig. 1 , Fig. 6) to the mixer (14) by second weighing means (13), preferably in the form of a weighing hopper.

Afterwards a mixer (14) carries out (Fig. 1 , Fig. 5, Fig. 6) the mixing of the various components to obtain the mixture in the form of bituminous conglomerates containing inert lithic materials, binder and filler plus any recycled conglomerates.

The binder, preferably bitumen, is proportioned by weight and is stored at a temperature that facilitates its pumping. The binder is dispensed towards the mixer (14) at a temperature that provides the best results during the phase of mixing with the

conglomerate. The heating occurs by means of a thermal unit of the plant, which is separate with respect to the represented plant portion. The thermal unit consists of one or more tanks heated by corresponding one or more boilers or electrical resistors. The inert lithic materials plus any recycled conglomerates, the binder and the filler are introduced in sequence in the mixer (14) that physically makes the mixture obtaining the mixture in the form of bituminous conglomerates. In order to optimize production times, the components that will have to be introduced in the mixer (14) later are weighed while a mixing of the previously introduced components is already in progress. The so produced conglomerate can be stored directly or by means of grab buckets or transport shuttles in suitable storage and deposit means (35) in a phase of storage of the mixture in the form of bituminous conglomerates. Preferably the storage and deposit means (35) are made in the form of silos. In the described embodiment the storage and deposit means (35) are placed below the mixer (14), but in alternative embodiments the storage and deposit means (35) can also be placed laterally with respect to the main body of the schematically illustrated plant. The trucks (7), that is to say, the vehicles for the transport of the conglomerate, are refilled directly from the storage and deposit means (35) under the control of the control unit (18) under the supervision of the operator that adjusts or sets the quantity of mixture in the form of bituminous conglomerates that is released by the storage and deposit means (35). The control unit (18) preferably enables the control of the whole production cycle by means of a management, supervision and setting system.

During the production of mixtures in the form of bituminous conglomerates and also during the loading phases on the trucks (7) it is possible to have diffuse emissions containing polluting compounds, such as organic components, normally defined as volatile organic compounds (VOCs), aromatic polycyclic hydrocarbons (APHs), etc. Advantageously it is provided that the polluting compounds are sucked preventing their release into the environment and that such polluting compounds are opportunely damped and eliminated as will be explained in the following of the present description.

In particular it is provided that such polluting compounds are burnt by means of the exposure to suitable temperatures higher than 400°C, preferably higher than 600°C. In fact, it has been found that at temperatures higher than those indicated the polluting compounds are easily combustible by means of thermal oxidation if exposed to such temperatures for a sufficient period of time, of the order of a few seconds, preferably in a range between 1 and 5 seconds, even more preferably in a range between 1.5 and 2 seconds.

As a consequence in the plant one can also provide an operating method that includes one or both of the following phases:

- a phase of adjustment of the combustion temperature of the polluting compounds by means (Fig. 11) of the at least one flame (49) of the burner within the dryer (4), said combustion temperature being higher than 400°C, preferably higher than 600°C;

- a phase of slowdown of the speed of the airflow within the dryer (4), said slowdown of the speed of the airflow causing an increase in the permanence time of the polluting compounds within the dryer (4), the permanence time of the polluting compounds within the dryer (4) being preferably in a range between 1 and 5 seconds, even more preferably in a range between 1.5 and 2 seconds.

The principle of operation, in this case, provides that the polluting compounds are sucked together with the air by means of drawing or suction means from one or more zones that are subject to the presence of such polluting compounds. For example one can provide first drawing or suction means (37') in correspondence of at least one loading station of the trucks (7) in such a way as to enable the suction of the polluting compounds also during the phases of loading of the trucks (7). In order to efficiently prevent the input of the polluting compounds into the environment it can be provided that the first drawing or suction means (37') are installed according to a configuration such as to suck the air from a cabin or tunnel within which the truck (7) can enter during the loading phases. The cabin will preferably be essentially airtight in such a way that the cabin is maintained under depression by means of the first drawing or suction means themselves, thus efficiently preventing the emissions into the environment. Furthermore, for example, one can provide second drawing or suction means (37") in correspondence of the mixer (14). Furthermore, for example, one can provide third drawing or suction means in correspondence of conveyor means of the bituminous conglomerates towards the one or more storage silos as well as fourth drawing or suction means of the air with polluting compounds from the storage silos of the bituminous conglomerates.

The suction of the air with polluting compounds will preferably occur by means of a second suction system (39), distinct with respect to the first suction system (16) of air from the dryer. In practice the second suction system (39) will comprise introduction means (40) of the airflow containing the polluting compounds within the first dryer portion (4'), for example in the form of at least one second connection (38) in the form of a pipe connecting the drawing means (37', 37") or suction means to the first dryer portion (4') (4). The second suction system (39) of the air with polluting compounds comprises a respective suction fan that conveys the air with polluting compounds towards a respective filtering device (41) of the air with polluting compounds. The second suction system (39) of the air with polluting compounds is connected in such a way as to convey the air with polluting compounds towards the first dryer portion (4') of the plant (1) where there is the flame (49) of the burner (5), in particular in such a way as to convey the air in correspondence of the outlet zone of the material from the first dryer portion (4'), the airflow being oriented in countercurrent with respect to the direction of advancement (27) of the material within the first dryer portion (4').

In particular said solution, described in Patent Application UD2014A000178, in the name of the same applicant and that is incorporated as reference herein, describes, with reference to the solution as in the present application, a plant for the production and distribution of bituminous conglomerates provided with a dryer (4) wherein the first dryer portion (4') comprises (Fig. 6) at least one feeding device (25, 26) of inert lithic materials, a burner (5) generating at least one flame (49) that generates drying heat of the materials to be treated, at least one discharge head for the extraction of the treated materials from the first dryer portion (4'), a first suction system (16) of air from the dryer (4). The first dryer portion (4') is provided with connecting means to a damping system (36) of polluting compounds that are generated in the plant (1 ), the damping system (36) of polluting compounds comprising:

- generation means (37', 37", 39) of an airflow containing the polluting compounds which are drawn from the plant (1);

- introduction means (38, 40) of the airflow containing the polluting compounds within the first dryer portion (4') by means of an aspirator (39).

The first dryer portion (4') comprises deviation means of the airflow containing the polluting compounds which are configured to deviate the airflow towards a perimetrically external surface or shell of the first dryer portion (4'). The deviation means are configured and structured to move away the airflow at least from a generation zone of the at least one flame (49) and the deviation means are configured and structured to generate a turbulence in the airflow increasing the permanence time of the polluting compounds within the first dryer portion (4'). The at least one flame (49) of the burner (5) causes a combustion of the polluting compounds.

The deviation means of the airflow containing the polluting compounds towards the flame (49) of the burner (5) are configured and structured to convey the polluting compounds according to a conveying direction which is oriented concordantly with a direction according to which the flame (49) is oriented. Furthermore, there are adjustment means of the combustion temperature of the polluting compounds by means of the flame (49), the combustion temperature being higher than 400°C, preferably higher than 600°C.

The deviation means can for example be selected from one or more of the following:

- a deflector or section reducer preferably made of refractory steel, which facilitates the holding of the airflow with the polluting compounds in a first chamber or combustion chamber (45) of the first dryer portion (4') and further facilitates the

establishment of a turbulent motion, the deflector or section reducer (48) being configured to prevent the airflow from exiting the first chamber (45);

- a screen of the airflow which is configured and structured to deviate the airflow with the polluting compounds in such a way that the airflow is directed according to a direction of advancement essentially oriented towards the zone of the flame

(49) in which the temperature of the flame (49) itself is higher, that is to say, essentially in such a way that the airflow is directed towards the external part of the flame (49).

In one embodiment there can be both the deflector or section reducer and the screen according to a configuration in which they are spaced apart with respect to each other and facing each other, the screen being arranged essentially around the burner (5) in such a way as to surround at least an initial part of the flame (49) and the deflector or section reducer being arranged in an advanced position with respect to the screen, wherein the term advanced position refers to the direction of advancement of the airflow, the deflector or section reducer being placed near a zone of the first dryer portion (4') essentially corresponding to an end zone of the development of the flame (49).

The generation means of the airflow are configured and structured to adjust the airflow obtaining an airflow in a range from about 1000 to about 20000 Nm3/h of air with a constant flow rate, wherein Nm3/h refers to a measurement of the flow rate in m3/h under normal pressure and temperature conditions of 1 atmosphere and 20°C respectively.

One can also provide adjustment or switching means of the operating power of the burner (5) between at least two different power levels of which a first power level having a lower operating power with respect to the operating power of a second power level, in which:

- the first power level is such as to cause said combustion of the polluting compounds in the absence of materials to be treated within the first dryer portion (4'), for example during phases of mere loading of the trucks (7) in the absence of production;

- the second power level is such as to cause the combustion of the polluting compounds in the presence of materials to be treated within the dryer.

For example the power of the first power level can be between about 1/6 and 1/3 of the power of the second power level, preferably the power of the first power level being between about 1/5 and 1/4 of the power of the second power level.

For example the power of the first power level can be between 1.5 and 7 MW, preferably between 2 and 6 MW, even more preferably between about 2.5 and about 3.5 MW and the power of the second power level can be between 9 and 24 MW, preferably between 12 and 22 MW, even more preferably between about 15 and about 20 MW, for a production rate of about 280 tons/hour of conglomerate.

Furthermore, one can also provide a solution in which the adjustment or switching means of the operating power of the burner (5) are configured for the switching between at least three different power levels of which the previously defined first power level having a lower operating power with respect to the

operating power of the previously defined second power level, and further a third power level between the first power level and the second power level, the third power level being such as to cause mainly or only the drying of the materials to be treated within the first dryer portion (4'). For example the power of the third power level is between about 2/3 and 3/3 of the power of the second power level. For example the power of the third power level is between 7 and 15 MW, preferably between 8 and 14 MW, even more preferably between about 9 and about 12 MW, for a production rate of about 140-180 tons/hour of conglomerate.

WE Claims

1. Plant (1) for the production and distribution of bituminous conglomerates comprising:

- at least one dryer (4) for drying materials to be treated wherein the dryer (4) is provided with at least one burner (5) generating drying heat for the materials to be treated by means of at least one flame (49) of the at least one burner (5), obtaining treated materials;

- a first suction system (16) of hot air from said dryer (4);

- a mixer (14) for mixing at least the treated materials;

- a control unit (18);

wherein the plant (1 ) is adapted and intended for the treatment of the materials to be treated including inert lithic materials and materials containing bitumen, bituminous conglomerates or recycled bituminous material or mixed materials containing at least one part of materials containing bitumen, in which the dryer (4) is made up of at least one first dryer portion (4') and of a second dryer portion (4") which are arranged one after the other with the interposition of a hot air passage compartment (22) between the first dryer portion (4') and the second dryer portion (4"), in which the material advances within the first dryer portion (4') according to a direction of advancement (27) of the material in the first dryer portion (4') and in which the material advances within the second dryer portion (4") according to a direction of advancement (28) of the material in the second dryer portion (4"), and further in which the first dryer portion (4') is provided with said burner (5) generating drying heat for the materials present within the first dryer portion (4') and wherein said first suction system (16) of hot air sucks hot air from said dryer (4) with the establishment of a hot airflow oriented from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4") in which the dryer (4) comprises adjustable deviation means (32, 33) for the deviation or for the adjustment of the quantity of said hot airflow oriented from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4") characterized in that the first dryer portion (4') is divided into two zones of which a first zone constitutes a first chamber or combustion chamber (45) in which the flame (49) of the burner (5) develops and of which a second zone constitutes a second chamber or drying chamber (46) within which said materials are present, the first dryer portion (4') being provided with a passage (43) integral with the first dryer portion (4') itself, the passage (43) putting in communication the combustion chamber (45) of the first dryer portion (4') with the second dryer portion (4") generating a preferential path for a high temperature gas flow for heating the material of the second dryer portion (4"),

the first dryer portion (4') being thus intended to constitute:

- a supply conduit of the hot airflow produced by the burner (5) towards the second dryer portion (4") in a condition in which materials to be treated are not present inside the first dryer portion (4');

or

- the portion for the treatment of the materials to be treated inside the first dryer portion (4') in a condition in which materials to be treated are not present inside the second dryer portion (4");

or

- both a supply conduit of the hot airflow produced by the burner (5) towards the second dryer portion (4") and the portion for the treatment of the materials to be treated inside the first dryer portion (4') in a condition in which materials to be treated are present both inside the first dryer portion (4') and the second dryer portion (4").

2. Plant (1 ) for the production and distribution of bituminous conglomerates according to the previous claim characterised in that

the passage (43) has a diameter of about 1/3 with respect to the external

diameter of the first dryer portion (4').

3. Plant (1) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that the passage (43) has a length between 1/3 and 2/3 with respect to the length of the second drying chamber (46) of the first dryer portion (4').

4. Plant (1 ) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the passage (43) has an adjustable finning (44) for opening or closing or adjusting the high temperature gas flow.

5. Plant (1 ) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the first dryer portion (4') constitutes the drying and heating portion for the inert lithic materials and the second dryer portion (4") constitutes the drying and heating portion for the materials containing bitumen, bituminous conglomerates or recycled bituminous material or mixed materials containing at least one part of materials containing bitumen.

6. Plant (1 ) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the first dryer portion (4') provided with the burner (5) constitutes a combustion zone for the production of hot air of said hot airflow oriented from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4").

7. Plant (1 ) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the second dryer portion (4") is devoid of a respective burner intended for the generation of heat for drying the materials which are present within the second dryer portion (4"), the whole drying heat of the materials which are present within the second dryer portion (4") being generated by means of said burner (5) of the first dryer portion (4') said heat being transferred to said second dryer

portion (4") by means of said hot airflow oriented from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4").

8. Plant (1 ) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the flame (49) of the burner (5) of the first dryer portion (4') is oriented according to a direction of the flame (49) which is opposite with respect to the direction of advancement (27) of the material within the first dryer portion (4')

and further characterised in that

the hot airflow from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4") is oriented in countercurrent with respect to the direction of advancement (27) of the material within the first dryer portion (4') and within the second dryer portion (4").

9. Plant (1 ) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the dryer (4) as a whole, consisting of the first dryer portion (4') and of the second dryer portion (4"), is provided with said burner (5) which is the one and only burner of the dryer (4) as a whole.

10. Plant (1) for the production and distribution of bituminous conglomerates according to the previous claim characterised in that

said burner (5) has a rated power lower than or equal to 24MW, preferably lower than or equal to 20MW.

11. Plant (1 ) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the hot air passage compartment (22) between the first dryer portion (4') and the second dryer portion (4") consists of a deviation compartment for the hot air flow comprising:

- an inlet for hot air from the first dryer portion (4');

- a first outlet for hot air from inside the deviation compartment towards the second dryer portion (4"), the second dryer portion (4") being connected to

the first suction system (16) of hot air for the establishment of said hot airflow oriented from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4");

- a second outlet for hot air from inside the deviation compartment towards a

suction conduit (21) connected to the first suction system (16) of hot air for the establishment of a secondary airflow from the first dryer portion (4') towards the first suction system (16) without crossing the second dryer portion (4");

the adjustable deviation means (32, 33) comprising a first shutter (32) which is settable on at least three positions of which:

- a first position in which the first shutter (32) leaves completely free the hot airflow towards the second dryer portion (4"), in which all the hot air sucked from the first dryer portion (4') is conveyed towards the second dryer portion (4");

- a second position in which the first shutter (32) completely blocks the hot airflow towards the second dryer portion (4"), in which all the hot air sucked from the first dryer portion (4') is conveyed towards the suction conduit (21 ) without crossing the second dryer portion (4");

- a third position in which the first shutter (32) leaves partially free the hot airflow towards the second dryer portion (4"), with the partialization of the hot air sucked from the first dryer portion (4') between the second dryer portion (4") and the suction conduit (21).

12. Plant (1) for the production and distribution of bituminous conglomerates according to the previous claim characterised in that

the suction conduit (21) is provided with said adjustable deviation means (32, 33) in the form of a second shutter (33) for adjusting the quantity of hot air constituting said secondary airflow from the first dryer portion (4') towards the first suction system (16) without crossing the second dryer portion (4"), the

second shutter (33) being settable on at least three positions of which:

- a first position in which the second shutter (33) completely shuts the suction conduit (21);

- a second position in which the second shutter (33) leaves completely free the airflow within the suction conduit (21);

- a third position in which the second shutter (33) partially shuts the suction conduit (21).

13. Plant (1) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the first chamber or combustion chamber (45) is provided with containment blades of said materials avoiding a rain-like fall of the materials through the flame (49) produced by the burner (5).

14. Plant (1) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the first dryer portion (4') comprises a first feeding device (25) and a second feeding device (26) for the introduction of said materials into the first dryer portion (4') in which the first feeding device (25) feeds a first series of upstream circumferential openings (34) while the second feeding device (26) feeds a second series of downstream circumferential openings (34), the terms upstream and downstream being defined with respect to a direction of advancement (27) of the materials within the first dryer portion (4'), the first feeding device (25) and the first series of circumferential openings (34) being placed in correspondence of or in proximity to a head end of the first dryer portion (4'), the second feeding device (26) and the second series of circumferential openings (34) being placed spaced apart with respect to the first feeding device (25) according to the direction of advancement of the material, the second feeding device (26) being placed in correspondence of or in proximity to a position between the head end of the first dryer portion (4') and an outlet end of the materials from the first dryer portion (4').

15. Plant (1) for the production and distribution of bituminous conglomerates according to the previous claim characterised in that

the first feeding device (25) and the first series of circumferential openings (34) are placed spaced apart with respect to the second feeding device (26) and to the second series of circumferential openings (34) by a distance between 25% and 75% of the

overall length of the second drying chamber, preferably between 1 and 3 metres.

16. Plant (1) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the dryer (4), consisting of the first dryer portion (4') and of the second dryer portion (4") placed one after the other with the interposition of the hot air passage compartment (22) between the first dryer portion (4') and the second dryer portion (4"), is placed on the upper part with respect to deposit means (23) of treated materials containing bitumen, bituminous conglomerates or recycled bituminous material or mixed materials containing at least one part of materials containing bitumen, the plant (1 ) being provided with first gravity conveyor means of the treated materials containing bitumen towards the deposit means (23) of treated materials containing bitumen, in which the first conveyor means of the treated materials containing bitumen are devoid of heating means and further characterised in that

the dryer (4), consisting of the first dryer portion (4') and of the second dryer portion (4") placed one after the other with the interposition of the hot air passage compartment (22) between the first dryer portion (4') and the second dryer portion (4"), is placed on the upper part with respect to a sieve (9) for dividing the inert lithic materials according to the size of the inert lithic materials themselves, the plant (1) being provided with second gravity conveyor means of the inert lithic materials towards the sieve (9).

17. Plant (1 ) for the production and distribution of bituminous conglomerates

according to any of the previous claims characterised in that

the first suction system (16) of hot air comprises a pre-separation device (20) provided with a separation compartment for the separation and collection of polluting particles present in the hot air sucked from the dryer (4), the plant (1 ) further comprising one or more cochlea devices (17', 17") for transportation of the collected polluting particles for their reintroduction in the plant, said one or more cochlea devices (17', 17") comprising at least one cochlea device selected from:

- a first cochlea device (17') for transportation of the collected polluting particles for their feeding to the treated materials containing bitumen, bituminous conglomerates or recycled bituminous material or mixed materials containing at least one part of materials containing bitumen;

- a second cochlea device (17") for transportation of the collected polluting particles for their feeding to the treated inert lithic materials.

18. Plant (1) for the production and distribution of bituminous conglomerates according to the previous claim characterised in that

it comprises recirculation means of gases coming from the separation compartment of the pre-separation device (20) towards the first dryer portion (4') for their burning.

19. Plant (1) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the plant is provided with a damping system (36) of polluting compounds, the first dryer portion (4') being provided with connecting means to said damping system (36) of polluting compounds that are generated in the plant (1 ), the damping system (36) of polluting compounds comprising:

- generation means (37', 37", 39) of an airflow containing the polluting compounds which are drawn from the plant (1);

- introduction means (38, 40) of the airflow containing the polluting compounds within the first dryer portion (4');

the first dryer portion (4') comprising deviation means of the airflow containing the polluting compounds which are configured to deviate the airflow towards a perimetrically external surface or shell of the first dryer portion (4'), the deviation means being configured and structured to move away the airflow at least from a generation zone of the flame (49) of the burner (5) and the deviation means being configured and structured to generate a turbulence in the airflow increasing the permanence time of the polluting compounds within the first dryer portion (4'), the flame (49) of the burner (5) causing a combustion of the polluting compounds.

20. Plant (1) for the production and distribution of bituminous conglomerates according to the previous claim characterised in that

the generation means (37', 37", 39) of the airflow containing the polluting compounds comprise drawing means or suction means which are placed in correspondence of one or more suction positions selected from:

- suction position in correspondence of a loading station of one or more road transport vehicles or trucks (7) provided with first drawing or suction means (37');

- suction position in correspondence of one or more devices for the production of the bituminous conglomerates, wherein the devices for the production of the bituminous conglomerates are provided with second drawing or suction means

(37");

- suction position in correspondence of the mixer (14);

- suction position in correspondence of a cover hood of transport zones of the bituminous conglomerates, the cover hood being provided with third drawing or suction means.

21. Plant (1) for the production and distribution of bituminous conglomerates according to any of the previous claims 19 to 20 characterised in that

the deviation means of the airflow containing the polluting compounds towards the flame (49) of the burner (5) are configured and structured to convey the polluting compounds according to a conveying direction which is oriented concordantly with a direction according to which the flame (49) of the burner is oriented.

22. Plant (1) for the production and distribution of bituminous conglomerates according to any of the previous claims 19 to 21 characterised in that

the control unit (18) comprises adjustment means of the combustion temperature of the polluting compounds by means of the flame (49), the combustion temperature being higher than 400°C, preferably higher than 600°C.

23. Plant (1) for the production and distribution of bituminous conglomerates according to any of the previous claims 19 to 22 characterised in that

the control unit (18) is configured and structured to control the generation means (37', 37", 39) of the airflow in such a way as to adjust the airflow obtaining an airflow in a range from about 1000 to about 20000 Nm3/h of air with a constant flow rate, wherein Nm3/h refers to a measurement of the flow rate in m3/h under normal pressure and temperature conditions of 1 atmosphere and 20°C respectively.

24. Plant (1) for the production and distribution of bituminous conglomerates according to any of the previous claims characterised in that

the control unit (18) is configured and structured to control the plant (1) according to an operating method that comprises at least one switching phase between different operating modes of which:

- a first operating mode in which the burner (5) of the dryer (4) produces heat both for the treatment of the materials within the first dryer portion (4') and for the treatment of the materials within the second dryer portion (4"), the heat supplied to the second dryer portion (4") being supplied by means of the hot drying air extracted from the first dryer portion (4');

- a second operating mode in which the burner (5) of the dryer (4) produces heat only for the treatment of the materials within the first dryer portion (4');

- a third operating mode in which the burner (5) of the dryer (4) produces heat only for the treatment of the materials within the second dryer portion (4"), the heat supplied to the second dryer portion (4") being supplied by means of the hot drying air extracted from the first dryer portion (4') within which no material treatment occurs, the first dryer portion (4') acting as a feeding conduit of the hot air produced by the burner (5).

25. Plant (1) for the production and distribution of bituminous conglomerates according to the previous claim characterised in that

the control unit (18) is configured and structured to control the plant (1) according to an operating method in which in the first or in the third operating mode there is a phase of control of the quantity of said hot airflow oriented from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4"), the phase of control occurring by means of the adjustable deviation means (32, 33) for the deviation or for the adjustment of the quantity of said hot airflow oriented from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4"), the phase of control involving an adjustment of the hot airflow by means of the adjustable deviation means (32, 33) in such a way that the temperature of the hot airflow coming from the second dryer portion (4") is higher than 100°C.

26. Plant (1) for the production and distribution of bituminous conglomerates according to claim 27 characterised in that

the control unit (18) is configured and structured to control the plant (1) according to an operating method in which in the first or in the third operating mode there is a phase of control of the quantity of said hot airflow oriented from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4"), the phase of control occurring by means of the adjustable deviation

means (32, 33) for the deviation or for the adjustment of the quantity of said hot airflow oriented from the first dryer portion (4') provided with the burner (5) towards the second dryer portion (4"), the phase of control involving an adjustment of the hot airflow by means of the adjustable deviation means (32, 33) in such a way that the temperature of the hot airflow at the inlet of the second dryer portion (4") is of about 500 - 600°C.

27. Plant (1) for the production and distribution of bituminous conglomerates according to claim 24 and according to claim 14 characterised in that

the operating method comprises a phase of control of the process in which a feeding phase of materials within the first dryer portion (4') provides a switching phase between a feeding condition of the materials within the first dryer portion (4') by means of the first feeding device (25) and a feeding condition of the materials within the first dryer portion (4') by means of the second feeding device (26) according to the temperature detected in a phase of measurement of the temperature in the second dryer portion (4").