EP3221517B1

EP3221517B1 - Dryer for a plant for the production and distribution of bituminous conglomerates

Info

Publication number: EP3221517B1
Application number: EP15798326.3A
Authority: EP
Inventors: Enrico BERTONI; Francesco BIGNARDI; Andrea Pirazzini; Nereo Portello
Original assignee: Marini SpA
Current assignee: Marini SpA
Priority date: 2014-11-18
Filing date: 2015-11-16
Publication date: 2019-01-09
Anticipated expiration: 2035-11-16
Also published as: WO2016078755A1; EP3221517A1; ES2718553T3

Description

Technical field

The present invention relates to a method, apparatus and plant for damping polluting compounds produced during the production of mixtures in the form of conglomerates with bituminous and non-bituminous binders by means of a dryer provided with at least one burner. The invention is usefully, although not exclusively, applied 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.
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 advancement direction 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 several chambers communicating with each other. The burner is provided with a respective nozzle which 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.

Problems of the prior art

The prior art solutions are not effective in the reduction of polluting emissions in the external environment. In particular, they are ineffective in ensuring a correct elimination of polluting compounds such as fugitive emissions containing organic compounds, polycyclic aromatic hydrocarbons and other polluting compounds during the phases of generation and storage of the bituminous mixture and during the phases of delivery of the bituminous mixture towards the truck or transport means which are loaded with the bituminous mixture to carry it where it must be used.
Some prior art solutions are conceived in such a way that the polluting compounds are sucked from some zones where they are originated and are sent to filtering means, which, however, it being a process in which there are clogging oily components, are subject to frequent clogs which may jeopardize functionality reducing the effectiveness of suction of the polluting compounds. Furthermore, it is also necessary to provide periodic inspections of the filters and their replacement.
Furthermore, the prior art solutions are highly ineffective in the prevention of the emissions of polluting compounds during the phases of loading of the mixtures in the form of conglomerates with binders on the transport means which have to carry them to the place in which the mixtures have to be used.

Aim of the invention

The aim of the present invention is to provide a dryer and a plant which ensure an effective damping of polluting compounds produced during the production of mixtures in the form of conglomerates with bituminous and non-bituminous binders.

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, presents various advantages.
The solution according to the present invention allows to significantly reduce the release into the environment of polluting compounds during the production of mixtures in the form of conglomerates with bituminous and non-bituminous binders.
Furthermore, the solution according to the present invention allows to significantly reduce the release into the environment of polluting compounds also during the phases of loading and generation of the mixtures in the form of conglomerates with binders on the transport means.
The solution according to the present invention allows to reduce the problems of clogging of the filtering means used in the plant.

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 shows a first possible embodiment of a plant according to the present invention in which the storage silos for storing the produced mixture are located laterally with respect to the mixing tower.
Fig. 2 shows a detail of a part of the plant of Fig. 1.
Fig. 3 shows a possible second embodiment of a plant according to the present invention in which the storage silos for storing the produced mixture are located below with respect to the mixing tower.
Fig. 4 shows a detail of a part of the plant of Fig. 3.
Fig. 5 schematically shows the devices present in the plant of Fig. 3.
Fig. 6 schematically shows the devices present in the plant of Fig. 1.
Fig. 7 schematically shows in greater detail the devices present in the plant of Fig. 1.
Fig. 8 shows an enlargement of the section indicated with "A" in Fig. 7.
Fig. 9 shows an enlargement of the section indicated with "B" in Fig. 7.
Fig. 10 shows an enlargement of the section indicated with "C" in Fig. 7.
Fig. 11 schematically shows in greater detail a section of the dryer used in the present invention.
Fig. 12 shows an enlargement of the section indicated with "D" in Fig. 11.
Fig. 13 shows an enlargement of the section indicated with "E" in Fig. 11.
Fig. 14 shows an enlargement of the section indicated with "F" in Fig. 11.

Description of the invention

With reference to the figures (Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9), the present invention is generally applied to a plant (21) 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.

The invention is usefully, although not exclusively, applied in the production of bituminous conglomerate, in particular for road paving.
The plant (21) operates according to a production cycle which starts with a phase of selection and feeding of the inert lithic materials from suitable first storage means (1) and ends with the loading of the conglomerate (Fig. 7, Fig. 8) towards transport trucks (22), the loading being able to occur in correspondence of a first loading station (45) from one or more storage silos (17) for storing the bituminous conglomerates or in a second loading station (46) obtained in correspondence of first transport means (3') of the bituminous conglomerates towards the one or more silos (17) in order to allow for the loading of the transport truck (22) also during the phases of production and filling of the one or more silos (17). The production cycle occurs by means of the synchronization of a series of phases and intermediate operations. A mechanical means, generally a mechanical blade, takes (Fig. 1) the inert lithic materials from heaps (47) and loads them in different first storage means (1) depending on the different granulometry. For example there can be (Fig. 1, Fig. 3, Fig. 5, Fig. 6) distinct first storage means (1) for inert lithic materials having small granulometry, for inert lithic materials having medium-sized granulometry, for inert lithic materials having large-sized granulometry. In this way one can carry out a selective feeding on the basis of the granulometry of the inert lithic materials, which can thus be sent selectively, by second transport means (3"), towards the devices which are located downstream with respect to the advancement direction of the material to be subjected to the following operating phases of the process, in particular a first operating phase of drying which occurs in a dryer (4). The first storage means (1) can be provided with suitable pre-proportioning devices for sending directly the inert lithic materials of different granulometries in the correct quantities towards the devices which are located downstream with respect to the advancement direction of the material. The first storage means (1) are preferably made in form of hoppers open on their upper part to enable loading and closed with closing means which are openable in correspondence of the bottom which is intended to allow the release of the inert lithic materials on second transport means (3"), preferably in the form of a conveyor belt, even more preferably according to a configuration in which the second transport means (3") are an extractor belt, which is moved by a controlled variable-speed motor, thus directly obtaining a precise delivery of the inert lithic materials according to the quantities and the proportions required by the production formulation. The rate per hour of each of the first storage means (1) is proportional to the speed of the extractor belt.
For the production 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 (Fig. 1, Fig. 3, Fig. 5, Fig. 6) within second storage means (2), provided with a specific pre-proportioning device for this type of material. The recycled conglomerate can be for example made up of asphalt products from recycling. The recycled conglomerate coming from the second storage means (2), once supplied by the pre-proportioning device, can be sent to the dryer (4) by means of third transport means (3'") to be used as hot-recycled material, or can be sent directly downstream with respect to the dryer (4) to be used as cold-recycled material. In the case in which the recycled conglomerate is not preliminarily divided on the basis of granulometry, the plant (21) must also include (Fig. 1) a specific sieve (48) and a mill for reducing its size before the introduction into the plant. As an alternative (Fig. 3) the recycled conglomerates can be preliminarily divided on the basis of granulometry and stored in different second storage means (2) each of which is intended for a different granulometry.
A control unit (18) of the production cycle automatically performs the adjustment of the rate of each of the first storage means (1) and of any possible one or more second storage means (2).
The inert lithic materials and the recycled conglomerates, if present, are sent, by means of the second transport means (3") and the third transport means (3"') respectively, towards (Fig. 1, Fig. 3) the dryer (4) where they are heated to eliminate their humidity in an operating phase of drying. The removal of humidity facilitates the coating of inert lithic materials and recycled conglomerates, if present, with the binder, that is to say, the bitumen. To this purpose the dryer (4) is provided (Fig. 11, Fig. 12) with a burner (5), whose operation will be shown in the following of the present description. For a regular operation of the burner (5) it is necessary to suitably set the suction system (49) of the gases produced in the dryer (4) following the combustion performed by the burner (5).
During the drying phase the fine dusts are sucked (Fig. 1, Fig. 3, Fig. 5, Fig. 6, Fig. 7) from the dryer (4) by means of the suction system (49). The fine dusts are sent (Fig. 5, Fig. 6, Fig. 7, Fig. 10) to a first filter (6) by means of a second connection (27") and are damped in the dust exhaust first filter (6) in a filtering phase before the sucked and filtered air is released by means of fume exhaust means (29). The fine dusts are recovered in a hopper (19) which is located under the first filter (6). Some formulations of mixtures in the form of bituminous conglomerates are conceived in such a way that the mixture also contains, in addition to the previously described inert lithic materials and any possible recycled conglomerates, a certain amount of fine filling material (filler). Its function is to fill the spaces remaining between the various granulometries of inert lithic materials and any possible recycled conglomerates. The added or additional fine filling material is stored (Fig. 3, Fig. 5, Fig. 6) in suitable containers (7) in a storage phase of the fine materials produced during the drying phase. The fine materials are moved by means (Fig. 5) of a lifting device (59) for lifting the fine dusts.
After crossing the dryer (4) the inert lithic materials and any possible recycled conglomerates are sent to a mixing tower (28) where the process for obtaining the bituminous conglomerates continues. On exiting the dryer (4) the granulometries of inert lithic materials and any introduced recycled conglomerates are mixed witch each other. Sometimes it is appropriate, in order to improve their proportioning, to carry out a phase of additional selection of the materials with a separation on the basis of the respective granulometries. A first elevator (8), preferably a bucket elevator, introduces them (Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 9) into a screen (9) which divides the inert lithic materials and any recycled conglomerates according to the required sizes in a re-selection phase. The re-selected inert lithic materials and any recycled conglomerates are then stored in buffer means (10), preferably in the form of buffer hoppers. The buffer means, preferably a series of buffer hoppers made up of different buffer hoppers each of which is associated with a different granulometry range, interrupt the material flow, which until then preferably occurs without interruptions. By means of a proportioning phase, the various granulometries are proportioned by first weighing means (11). For example the various granulometries can be introduced in sequence one after the other into a weighing hopper suspended over loading cells carrying out a proportioning phase by the sum of the weights. The feeding of the various granulometries is carried out depending on the different production formulations, which it is possible to implement.
In the meanwhile the fine dusts, previously separated by means of the dust exhaust first filter (6) and accumulated in the hopper (19), are sent (Fig. 2) to a screw device (20) which is provided with a respective weighing system or, depending on the type of plant, are lifted by a fine dust lifting device (59), preferably in the form of a bucket elevator, and weighed by means of second weighing means (13), preferably in the form of a weighing hopper.
Afterwards a mixer (14) carries out (Fig. 2, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 9) 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 which facilitates its pumping. The binder is supplied towards the mixer (14), at a temperature which provides the best results during the phase of mixing with the conglomerate. The heating occurs by means of a thermal unit made up of one or more boilers (15) and tanks (16) which can be horizontal (Fig. 1) or vertical (Fig. 3). The inert lithic materials plus any recycled conglomerates, the binder and the filler are introduced in sequence into the mixer (14) which physically makes the mixture obtaining the mixture in the form of bituminous conglomerates. In order to optimize production time, the components which will have to be introduced later into the mixer (14) are weighed while a mixing of the previously introduced components is already taking place.
The so produced conglomerate can be stored (Fig. 1, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8) directly or by means of conveying buckets or shuttles in the storage silo (17) in a phase of storage of the mixture in the form of bituminous conglomerates. The trucks (22), that is to say, the vehicles intended for the transport of the conglomerate, are supplied directly from the storage silo (17) under the control of the control unit (18) with the supervision of the operator who adjusts or sets the amount of mixture in the form of bituminous conglomerates which is released from the storage silos (17).
The control unit (18) preferably allows to control 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 phases of loading on the trucks (22) in the first loading station (45) or in the second loading station (46) it is possible to have (Fig. 8) fugitive emissions containing polluting compounds, such as organic compounds, normally defined as volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), etc.
Advantageously, the present invention is conceived in such a way 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 the invention is conceived in such a way that such polluting compounds are burnt by means of the exposure to suitable temperatures higher than 400°C, preferably higher than 600C°. In fact, it was discovered that at temperatures higher than those indicated the polluting compounds are easily combustible by thermal oxidation if exposed to such temperatures for a sufficient period of time, of the order of some 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, the method can also comprise one of or both the following phases:

an adjusting phase of the combustion temperature of the polluting compounds by means of the at least one flame (50), said combustion temperature being higher than 400°C, preferably higher than 600C°;
a slowdown phase of the speed of the air flow (51), said slowdown of the speed of the air flow (51) causing an increase in the permanence time of the polluting compounds inside the dryer (4), the permanence time of the polluting compounds inside 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 according to the invention is conceived in such a way that the polluting compounds are sucked (Fig. 1, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9) along with the air by the drawing or suction means (23', 23", 23"') from one or more zones which are subject to the presence of such polluting compounds. For example one can provide (Fig. 1, Fig. 3, Fig. 7) first drawing or suction means (23') in correspondence of at least one loading station (45, 46) of the trucks (22), preferably in correspondence of a first loading station (45) from one or more storage silos (17) for storing the bituminous conglomerates or in correspondence of a second loading station (46) obtained in correspondence of first transport means (3') of the bituminous conglomerates towards the one or more silos (17) in such a way as to allow for the suction of the polluting compounds also during the phases of loading of the transport trucks (22) which occur during the phases of production and filling of the one or more silos (17). In order to efficiently prevent the release of the polluting compounds into the environment, it can be provided that the first drawing or suction means (23') are installed according to such a configuration as to suck (Fig. 3) the air from a room (24) into which the truck (22) can enter during the loading phases. The room (24) will preferably be essentially air-tight in such a way that the room (24) is kept in depression by means of the first drawing or suction means (23'), thus efficiently preventing the emissions into the environment. This solution may be adopted both with reference to the first loading station (45) and with reference to the second loading station (46) which have been previously described. Furthermore, for example, one can provide (Fig. 1, Fig. 6, Fig. 7) second drawing or suction means (23") in correspondence of the first transport means (3') which carry out the transport of the bituminous conglomerates towards the one or more storage silos (17). Furthermore, for example, one can provide (Fig. 4, Fig. 5, Fig. 6, Fig. 7) third drawing or suction means (23'") in correspondence of the mixing tower (28), preferably in correspondence of the devices used for the production of the bituminous conglomerates, such as in correspondence of the mixer (14).
The dryer (4) according to the invention for a plant (21) for the production and distribution of bituminous conglomerates comprises at least one inlet mouth (37) of inert materials (53), preferably inert lithic materials, at least one burner (5) which generates drying heat for the materials (53), at least one discharge head (42) for the extraction of the materials (53) from the dryer (4), a suction system (49) of air from the dryer (4) and further comprises a damping system (58) of polluting compounds which are generated in the plant (21), said damping system (58) of polluting compounds comprising:

generation means (23', 23", 23'", 26) of an air flow (51) containing the polluting compounds which are drawn from the plant (21);
introduction means (27', 43) of the air flow (51) containing the polluting compounds inside the dryer (4);
deviation means (30, 54) of the air flow (51) containing the polluting compounds towards a perimetrically external surface or shell of the dryer (4) which are configured and structured to spread apart the air flow (51) at least from the formation zone of at least one flame (50) generated by the at least one burner (5) and to generate a turbulence in the air flow (51) increasing the permanence time of the polluting compounds inside the dryer (4);

The generation means (23', 23", 23"', 26) of the air flow (51) containing the polluting compounds comprise drawing means or suction means (23', 23", 23"') of the polluting compounds. The introduction means (27', 43) of the air flow (51) containing the polluting compounds inside the dryer (4) comprise at least one first connection (27') connecting the drawing means or suction means (23', 23", 23'") to the dryer (4).
As a consequence, the plant (21) will be provided with a damping system (58) of the polluting compounds comprising collection means of the polluting compounds at least from the points where there can be emissions of polluting compounds possibly also directly from the points where the polluting compounds themselves develop. The drawing or suction means (23', 23", 23"') are connected (Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9) by means of the first connection (27') to the dryer (4) in order to send the sucked polluting compounds towards the burner (5). The suction by the drawing or suction means (23', 23", 23'") occurs by means of a fan (26) provided with a second filter (25) which is located upstream with respect to it and with respect to the air flow containing the polluting gases with sucked polluting compounds. The second filter (25) is a separating filter having sectors of pre-treatment of the sucked air which has the purpose of capturing the larger-sized particles contained in the flow, such as dusts, oils, etc.
The first connection (27') is connected (Fig. 5, Fig. 6, Fig. 7, Fig. 8) to the dryer (4) in a connecting position which is located upstream with respect to the position of the burner (5) and with respect to the direction of the air flow (51) inside the dryer (4). More precisely (Fig. 5, Fig. 6, Fig. 7, Fig. 9, Fig.11, Fig. 12) the air flow (51) containing the polluting compounds flows into the dryer from an entry (43) and is addressed towards the burner (5) in such a way that the flame (50) can carry out the combustion of the polluting compounds. After the combustion of the polluting compounds, the air flow (51) is addressed towards an exit (44) from which the air is recovered to be sent to the first filter (6). Preferably the air flow (51) occurs according to a flow direction which is essentially concordant with respect to the direction according to which the flame (50) of the burner (5) is oriented and occurs according to a flow direction which is essentially opposite with respect to the direction according to which the advancement of the material (53) occurs, which advances, therefore, according to a direction of the material flow (52) which is opposite with respect to the direction according to which the flame (50) of the burner (5) is oriented. In practice, therefore, the air flow (51) through the dryer (4) occurs in such a way as to ensure a suitably long contact time between the flame (50) and the polluting compounds and at a sufficiently high temperature with the consequent oxidation or combustion of the polluting compounds. To this purpose it was necessary to design a modified dryer (4) to be able to ensure the previously described conditions. The dryer (4) comprises at least one first chamber (31) in which the burner (5) introduces the flame (50) which is intended to generate the drying heat for the material (53) consisting of the inert lithic materials plus any recycled conglomerates. Preferably the air flow (51) containing the polluting compounds flows into the dryer from an entry (43) which is in communication with a second chamber (32) which constitutes a pre-introduction chamber or calming chamber which has the function of ensuring a suitable speed reduction of the air flow (51) before the introduction of the air flow (51) in the first chamber (31) in which the burner (5) introduces the flame (50).
The second chamber (32) is in flow communication with the first chamber (31) by means of openings (55) allowing the material (53) to exit the first chamber (31) and enter the second chamber (32) and then exit the dryer (4) to be sent to the following stations of processing of the material (53) to obtain the bituminous conglomerates.
The entry (43), which is connected to the first connection (27') of the damping system (58) is preferably in flow communication with said second chamber (32), so that the introduction of the air flow (51) in the dryer (4) occurs in correspondence of said second chamber (32). In this way, besides ensuring that the polluting compounds are exposed for a sufficient time to the high temperatures generated by the burner (5), the air flow (51) containing the polluting compounds is also prevented from significantly perturbing the flame (50) of the burner (5). In fact, it is necessary to remember that the main aim of the dryer (4) is to eliminate humidity from the material (53) and heat it to the desired temperature and, as a consequence, the use of the burner (5) to also perform the function of combustion of the polluting compounds must occur in such a way as to not interfere with the production process of the bituminous conglomerate. To this purpose, in order to ensure an effective conveying of the air flow (51) one preferably resorts to a shield (30) optionally in combination with or as an alternative to a deflector or section reducer (54) of the passage of the air flow (51) which allows to create a suitable turbulence of the polluting air flow inside the flame.
Therefore, to ensure a suitable permanence time of the polluting compounds in the first chamber (31) one preferably applies (Fig. 11) at least one of or both deviation means (30, 54) of the air flow (51) consisting of:

a deflector or section reducer (54) preferably made of refractory steel which facilitates the restraint of the air flow (51) with the polluting compounds in the first chamber (31) or combustion chamber, at the same time giving the air flow (51) a turbulent motion for the purpose of favouring the complete combustion of particles of the polluting compounds, said deflector or section reducer (54) being configured to slow down the exit of the air flow (51) from the first chamber (31);
a shield (30) of the air flow (51) which deviates the air flow (51) with the polluting compounds in such a way that the air flow (51) is directed according to an advancement direction which is essentially oriented towards the zone of the flame (50) in which the temperature of the flame itself is greater and the air flow (51) with lower temperature, because it comes from the drawing or suction means, is prevented from interfering with the initial part of the flame creating problems to the combustion.

Therefore, the deviation means (30, 54) of the air flow (51) containing the polluting compounds deviate the air flow (51) towards a perimetrically external surface or shell of the dryer (4) and they are configured and structured to spread apart the air flow (51) at least from the formation zone of at least one flame (50) generated by the at least one burner (5) and to generate a turbulence in the air flow (51) increasing the permanence time of the polluting compounds inside the dryer (4). The deviation means (30, 54) of the air flow (51) containing the polluting compounds are configured and structured to convey the air flow (51) and the polluting compounds according to a conveying direction which is oriented in a way concordant with a direction according to which the at least one flame (50) is oriented, thus preventing the air flow from excessively perturbing the flame whose main aim is to obtain the drying and the heating of the materials introduced into the dryer.
The shield (30) can be shaped according to a preferably frustoconical shape, wherein the frustoconical shape is arranged essentially around the end of the burner (5) where the flame is generated or arranged in such a way as to surround at least one initial part of the flame (50). The orientation of the frustoconical shape is arranged with an enlargement direction of the frustoconical shape oriented in a concordant way with respect to the advancement direction of the air flow (51) inside the dryer (4), that is to say, opposite to the direction (52) of the flow of material (53). Although reference is made to a frustoconical shape, it will be clear that one can also resort to other shapes which are suitable to obtain the same effect. Said shape contributes to preventing the air, having a low temperature with respect to the internal temperature of the dryer and of the flame, from coming into contact with and perturbing the flame in the initial part. In fact, in this way the shield deviates the air and is interposed between the air flow and at least the initial part of the flame, contributing to ensuring the operating conditions in which the air flow is oriented in such a way to come into contact with the flame in the zone in which the flame is at a greater temperature, favouring a complete combustion of the pollutants.
At least one part of the deviation means (30, 54) of the air flow (51) can be located between the first chamber (31) and the second chamber (32) of the dryer (4) and at least one part of the deviation means (30, 54) of the air flow (51) can be located between the first chamber (31) and the third chamber (33) of the dryer (4). In particular the deflector or section reducer (54) can be located between the first chamber (31) and the third chamber (33) of the dryer (4). In particular the shield (30) can be located between the first chamber (31) and the second chamber (32) of the dryer (4).
The method may also comprise an adjusting phase of the air flow (51) containing the polluting compounds and the plant (21) or the dryer (4) may be provided with generation means (23', 23", 23"', 26) of the air flow (51) which are configured and structured to adjust the air flow (51) obtaining an air flow (51) in a range from a minimum of about 1000 to a maximum of about 20000 Nm3/h air with a constant flow rate depending on the quantity of storage silos in the plant, wherein Nm3/h refers to a measurement of the flow rate in m3/h under normal conditions of pressure and temperature equal to 1 atmosphere and 20°C respectively. For plants provided with few storage silos (17) and, therefore, with a low storage capacity in which there are few loading stations (45, 46) of the product towards the trucks or road transport means (22), one can provide an adjustment of the air flow (51) in such a way as to obtain a smaller air flow (51) with respect to the case of plants having a great storage capacity. The installed burner (5) can be selected from:

a single burner having a variable power, in which case the operating method includes an adjusting phase of the operating power of said single burner having a variable power between the different power levels defined in the present description;
a multi-stage burner;
a burner consisting of at least two distinct burners.

That is to say, one can provide a configuration in which the at least one burner (5) consists of at least two distinct burners or of two distinct power stages of which:

a first burner or a first stage constitutes an auxiliary burner generating a first flame or auxiliary flame;
a second burner or a second stage constitutes a main burner generating a second flame or main flame.

In general, for all the previously listed kinds of burners, the characteristic which must be guaranteed is the burner (5) to be provided with adjusting or switching means to be able to operate at at least two different power levels, a first power level of which having a lower operating power with respect to the operating power of the second power level.
For example according to a power ratio in which the first power level is between about 1/6 and 1/3 of the second power level, preferably wherein the first power level is between about 1/5 and 1/4 of the second power level, even more preferably being about 1/5 of the second power level, independently of the embodiment of the burner which can be for example one of the previously listed types of burner (a single burner having a variable power, a multi-stage burner, at least two distinct burners). In fact, it is necessary to consider that the plant (21), and in particular the dryer (4) and the related burner (5), must be able to work in two distinct operating conditions which require operating powers of the burner (5) at at least two distinct power levels.
In the first case, that is to say, that in which the burner operates at the lower first power level, the plant (21) and the dryer (4) work in a first type of operating phase in which there is no material (53) inside the first chamber (31) of the dryer (4), said first type of operating phase corresponding to a first condition in which at least one truck (22) is loaded (Fig. 1, Fig. 3, Fig. 7) in at least one first loading station (45) which is located in correspondence of the storage silo (17) for storing the bituminous conglomerates while the production of additional bituminous conglomerate has stopped. That is to say, in said first condition the plant (21) has stopped relative to the production of new bituminous conglomerate but it works only as a loading system of the truck (22) with the previously produced bituminous conglomerate and stored in one or more storage silos (17) for storing the bituminous conglomerates and simultaneously the suction of the polluting compounds is active. In this case, that is to say, during the loading of at least one truck (22) with the production of bituminous conglomerate that has stopped, the system of collection of the polluting compounds is on and takes into the dryer (4) the air collected by means of the drawing or suction means (23', 23", 23'").
In the dryer (4) there is no material (53) to be processed and it is only used for the heating and the treatment of the air coming from the system of collection of the polluting compounds which sucks air at least from the first drawing or suction means (23') which are located in correspondence of a first loading station (45) from a silo (17) while a truck (22) is loaded.
In the second case, that is to say, that in which the burner operates at the greater second power level, the plant (21) and the dryer (4) work in a second type of operating phase in which there is material (53) inside the first chamber (31) of the dryer (4), said second type of operating phase corresponding to a second condition in which at least one truck (22) is loaded in at least one first loading station (45) or in at least one second loading station (46) or to a first condition in which at least one first truck (22) is loaded (Fig. 1, Fig. 3, Fig. 7) in at least one first loading station (45) and at least one second truck (22) is loaded in at least one second loading station (46), the first loading station (45) being that which is located in correspondence of the storage silo (17) for storing the bituminous conglomerates and the second loading station (46) being that which is obtained in correspondence of first transport means (3') of the bituminous conglomerates towards the one or more silos (17) in order to allow for the loading of the transport truck (22) also during the phases of production and filling of the one or more silos (17). In the second case, that is to say, that in which the burner operates at the greater second power level, the plant (21) and the dryer (4) work in a second type of operating phase in which the production of additional bituminous conglomerate occurs. That is to say, in said first condition the plant (21) works at full capacity and produces new bituminous conglomerate and simultaneously the suction of the polluting compounds is active. In this case, that is to say, during the production of bituminous conglomerate with the simultaneous loading of at least one truck (22), the system of collection of the polluting compounds is on and takes into the dryer (4) the air collected by means of the drawing or suction means (23', 23", 23"'). The burner (5) is adjusted to adsorb the constant air excess deriving from said collection of the polluting compounds and the first filter (6) will be automatically adjusted to keep the correct depression for the operation of the burner (5). The adjustment will occur for example by means of a blade damper or by means of inverter control.
One can also provide an additional third case corresponding to an operating condition in which the plant (21) and the dryer (4) work in a third type of operating phase in which there is material (53) inside the first chamber (31) of the dryer (4), said third type of operating phase corresponding to a third condition in which there are no trucks (22) to be loaded with bituminous conglomerate. In the third case the plant (21) works at full capacity and produces new bituminous conglomerate to be sent to the storage silos (17) without there being the delivery of bituminous conglomerate on the truck (22). In this case at least the suction of the polluting compounds from the first loading station (45) and second loading station (46) can be not active. However, the suction of the polluting compounds by the third drawing or suction means (23"') can be active in correspondence of the devices used for the production of the bituminous conglomerates of the plant (21). In said third case the burner can operate at a third power level equal to that of the third power level or included between the previously defined lower first power level and greater second power level, such as a third power level included between 2/3 and 3/3 of the second power level.
For example in the first described case, that is to say, that in which the burner operates at the lower first power level and the plant (21) and the dryer (4) work in a first type of operating phase in which there is no material (53) inside the first chamber (31) of the dryer (4) and the suction of the polluting compounds is active, one can operate at a power level between 1.5 and 8.5 MW, preferably between 2 and 7 MW, even more preferably between about 2.5 and about 3.5 MW.
For example in the second described case, that is to say, that in which the burner operates at the greater second power level and the plant (21) and the dryer (4) work in a second type of operating phase in which there is material (53) inside the first chamber (31) of the dryer (4) and simultaneously the suction of the polluting compounds is active, one can operate at a power level included between 9 and 25 MW, preferably between 12 and 22 MW, even more preferably between about 14 and about 18 MW for an indicative production rate of 200 tons/hour of conglomerate. Such values are to be considered dependent on the production capacity per hour of the plant (21). For example for a plant with output production volumes of bituminous conglomerate of 200 tons/hour one can provide values approximately of 14-16 MW. Furthermore, such values are to be considered dependent on the humidity of the inert material (53) introduced into the dryer (4) and on the final output temperature which is set according to production requirements, the provided values referring to a typical case of inert material (53) with 3% humidity and for a final output temperature of the material of about 160 centigrade degrees.
For example in the third described case, that is to say, that in which the burner operates at the third power level and the plant (21) and the dryer (4) work in a third type of operating phase in which there is material (53) inside the first chamber (31) of the dryer (4) and simultaneously the suction of the polluting compounds is not active at least for some of the drawing or suction means (23', 23", 23"'), one can operate at a power level included between 6 and 22 MW, preferably between 8 and 20 MW, even more preferably between about 10 and about 18 MW for an indicative production rate of 200 tons/hour of conglomerate. Such values are to be considered dependent on the production capacity per hour of the plant (21). For example for a plant with output production volumes of bituminous conglomerate of 200 tons/hour one can provide values approximately of 12-14 MW. Furthermore, such values are to be considered dependent on the humidity of the inert material (53) introduced into the dryer (4) and on the final output temperature which is set according to production requirements, the provided values referring to a typical case of inert material (53) with 3% humidity and for a final output temperature of the material of about 160 centigrade degrees.
The control unit (18) will be configured and structured to manage, in addition to the plant (21) as a whole, the damping system (58) of the polluting compounds as well. Once the operation of the damping system of the polluting compounds has been enabled, the flame (50) is not immediately started but its ignition occurs when the conditions required for its operation have been checked. Therefore, the damping system of the polluting compounds, once it has been enabled, remains on stand-by waiting for the required operating conditions to occur and, when such conditions occur, the damping system of the polluting compounds will be automatically started by the control unit (18). The start of the fan (26) of the polluting compounds and also the change in the power level of the burner (5) may lead to a lowering of the temperature at the entry of the first filter (6) and to an instability condition in the suction of the first filter (6).
In order to solve this drawback, the operation at the greater second power level must be suitably adjusted.
For example in the case of start of the plant (21) from an operating condition in which the plant (21) has completely stopped, it will be appropriate that the start of the damping system (58) of the polluting compounds occurs in advance with respect to the start of the production and late with respect to a stable flame signal, that is to say, when the burner is at full capacity. Therefore, it is necessary to first start the plant at the third power level, that is to say, that related to the condition in which the suction of the polluting compounds from the first loading station (45) and second loading station (46) is not active. In the case of a plant (21) with a dryer (4) provided with a single burner (5) having a variable power, for example, the plant (21) is initially started at a lower power level. Once production has been started, the burner (5) will be made to operate at the greater power level to also carry out the combustion of the polluting compounds.
In the case of a plant (21) with a dryer (4) provided with at least two distinct burners it can be provided that it is started initially with one single main flame of the burner (5) active and in the absence of another additional auxiliary flame of combustion of the polluting compounds. Once production has been started, the additional auxiliary flame of combustion of the polluting compounds will also be started.
The burner (5) can be provided with setting means of the main flame and, as a consequence, the operating method can include a setting phase of the main flame or of the power of the burner according to process parameters for example selected from temperature inside the dryer (4), air flow inside the dryer (4), quantity of material (53) to be treated, recipe for preparing the mixture, humidity of the material (53) to be treated, etc. Optionally, one can provide suitable sensors which measure one or more of the indicated values or one can provide modulations based on the specific recipe for preparing the mixture being worked.
The dryer can comprise adjusting means of the internal pressure, said adjusting means adjusting the pressure inside the dryer in such a way as to keep a condition of depression on an essentially constant value determined according to process parameters for example selected from temperature inside the dryer (4), air flow inside the dryer (4), quantity of material (53) to be treated, recipe for preparing the mixture, humidity of the material (53) to be treated, etc.
When the damping system (58) of the polluting compounds is started one activates the fan (26) which, through the first connection (27') causes the establishment of an air flow (51) in the dryer (4), said air flow (51) coming from the drawing or suction means (23', 23", 23"') and containing the polluting compounds.
Preferably the start of the damping system (58) of the volatile organic compounds will be affected by the presence of one or more operating conditions selected from:

lifting device (59) of the fine dusts activated;
first elevator (8) activated;
screw devices (20) activated;
suction system (49) activated;
movement means (35) for the rotation of the dryer (4) activated;
main flame or additional auxiliary flame present.

The damping system (58) of the polluting compounds always needs the presence of at least one flame (50) inside the dryer in order to have the combustion of the polluting compounds. The flame (50) can be:

the main flame provided for the real drying of the material (53) in the dryer (4), optionally powered to cause the combustion of the polluting compounds as well;
or
the additional auxiliary flame especially provided for the combustion of the polluting compounds;
or
an overall flame obtained by means of the simultaneous delivery of the main flame provided for the real drying of the material (53) in the dryer (4) and the additional auxiliary flame especially provided for the combustion of the polluting compounds.

Preferably, in the case in which the main flame is not present but its ignition phase is taking place (pre-ventilation cycle and safety controls of the burner) the fan (26) and the auxiliary flame will be turned off and will be kept off until the main flame has been started.
One can therefore provide a solution in which the burner is configured and structured to generate both a main flame for the drying of the material (53) and to generate an additional auxiliary flame for the combustion of the polluting compounds. Obviously completely similar considerations are valid in the case in which an additional auxiliary flame is not actually present but the combustion of the polluting compounds is essentially obtained by adjusting the power of the main flame to different power levels as previously explained.
In the case in which the main flame is not present and its ignition is not required, one can only ignite the additional auxiliary flame for the combustion of the polluting compounds. This situation is for example that corresponding to the previously described first case, that is to say, that in which the burner operates at the lower first power level, the plant (21) and the dryer (4) work in a first type of operating phase in which there is no material (53) inside the first chamber (31) of the dryer (4), said first type of operating phase corresponding to a first condition in which at least one truck (22) is loaded (Fig. 1, Fig. 3, Fig. 7) in at least one first loading station (45) which is located in correspondence of the storage silo (17) for storing the bituminous conglomerates while the production of additional bituminous conglomerate has stopped.
One can also provide configurations in which the main flame and the auxiliary flame are never ignited simultaneously. In that case, if the production of bituminous conglomerates is in progress, it will be only the main flame to also cause the combustion of the polluting compounds, optionally adjusting the power of the main flame to also take into account the presence of the air flow (51) containing the polluting compounds. In that case, if the production of bituminous conglomerates is not in progress, it will be only the additional auxiliary flame to also cause the combustion of the polluting compounds. In the phases of switching between the condition in which the main flame is in use and the condition in which the additional auxiliary flame is in use, the fan (26) will be preferably off.
In general one can therefore provide an operating method of a plant (21) for the production and distribution of bituminous conglomerates, wherein the plant (21) for the production and distribution of bituminous conglomerates operates according to at least one operating cycle selected from:

(A) operating cycle of production of bituminous conglomerates, said operating cycle of production of bituminous conglomerates comprising at least the following phases:
- (A1) feeding of at least inert materials (53), preferably inert lithic materials in correspondence of an inlet mouth (37) of a dryer (4) in the form of one or more rotating drums (34);
- (A2) ignition of at least one burner (5) generating drying heat for the inert materials (53) and turning on of at least one suction system (49) of air from the dryer (4);
- (A3) drying of the materials (53) with the activation of movement means (35) of the one or more rotating drums (34), said activation of the movement means (35) corresponding to a rotational phase of at least one of the rotating drums (34) causing the advancement of the materials (53) inside the rotating drums (34) in a condition of exposure to the drying heat according to an advancement direction of the flow of material (52);
- (A4) possible introduction of recycled conglomerates in the dryer (4);
- (A5) possible introduction of filling bituminous substances and binders in the dryer (4) by means of feeding means (41);
- (A6) extraction of the materials (53) in correspondence of a discharge head (42) of the dryer (4);
- (A7) mixing of the materials (53) with binders obtaining bituminous conglomerates by means of a mixing section (28);
- (A8) movement of the bituminous conglomerates and storage in one or more storage silos (17) by means of first transport means (3');
(B) operating cycle of distribution of bituminous conglomerates to one or more road transport machines (22) in the absence of production of bituminous conglomerates, said operating cycle of distribution of bituminous conglomerates comprising at least the following phases:
- (B1) turning on of mechanical devices of feeding of the bituminous conglomerates from the one or more storage silos (17);
- (B2) distribution of the bituminous conglomerates to one or more road transport machines (22);
(C) operating cycle of production of bituminous conglomerates with the simultaneous distribution of bituminous conglomerates to one or more road transport machines (22), said operating cycle of production of bituminous conglomerates with the simultaneous distribution of bituminous conglomerates to one or more road transport machines (22) comprising at least the previously described phases of the operating cycle of distribution (B) of bituminous conglomerates alternated with one or more of said phases of the operating cycle of production (A) of bituminous conglomerates.

The plant (21) comprises a damping system (58) of the polluting compounds and the operating method of the plant (21) for the production and distribution of bituminous conglomerates also comprises the following damping phases of polluting compounds which are generated in the plant (21):

(D1) suction of the polluting compounds by means of drawing means or suction means (23', 23", 23"') which are located in correspondence of at least one emission position of the polluting compounds;
(D2) transport of the sucked polluting compounds towards the dryer (4) by means of at least one first connection (27');
(D3) introduction of the sucked polluting compounds in the dryer (4) by means of an air flow (51);
(D4) conveying of the sucked polluting compounds towards at least one flame (50) generated by the at least one burner (5)
(D5) combustion of the polluting compounds by means of the at least one flame (50).

Similarly, one can also provide an operating method of a dryer (4) of a plant (21) for the production and distribution of bituminous conglomerates, wherein the dryer (4) operates according to at least one operating cycle (i) which is an operating cycle of drying of bituminous conglomerates, said operating cycle of drying of bituminous conglomerates comprising at least the previously described phases (A1), (A2), (A3), (A4), (A5), (A6). The operating method of the dryer (4) will further comprise a damping phase of polluting compounds which are generated in the plant (21), said damping phase comprising the previously described sub-phases (D1), (D2), (D3), (D4), (D5).
As previously explained, the at least one burner (5) can be configured and structured to operate at least at two distinct power levels and, as a consequence, the operating method can therefore include an adjusting or switching phase of the operating power of the at least one burner (5) between at least two distinct power levels, a first power level of which having a lower operating power with respect to the operating power of the second power level, wherein:

the first power level is adjusted in such a way as to cause the combustion of the polluting compounds in the phase (D5) in a first type of operating phase which occurs in the absence of materials (53) inside the dryer (4);
the second power level is adjusted in such a way as to cause the combustion of the polluting compounds in the phase (D5) in a second type of operating phase which occurs in the presence of the materials (53) inside the dryer (4) and in the presence of the conveying of the sucked polluting compounds towards the at least one flame (50).

In the previously described case of a burner (5) consisting of at least two distinct burners or of two distinct stages, the phase (A2) is an ignition phase of the main burner, said main burner generating drying heat for the inert materials (53) and the combustion phase (D5) of the polluting compounds occurs by means of the second flame generated by the main burner.
In the operating cycle (B) of distribution of bituminous conglomerates from the silo (17) in the absence of production of bituminous conglomerates, the cycle (B) can further comprise an ignition phase of the auxiliary burner generating the first flame, the combustion phase (D5) of the polluting compounds occurring by means of said first flame generated by the auxiliary burner.
The operating method can also include an adjusting or switching phase of the operating power of the at least one burner (5) between at least three distinct power levels, of which the previously described first power level and second power level and an additional third power level between the first power level and the second power level, said third power level being adjusted in such a way as to cause in a third type of operating phase only the drying of the materials (53) in the absence of the conveying of the sucked polluting compounds.
The activation of the fan (26) preferably occurs gradually by means of a starting ramp, the fan (26) being controlled by means of an inverter or a soft-starter.
The starting ramp is preferably soft or not too inclined to prevent excessive pressure changes in the management of the depression of the first filter (6).
For example a cycle (M) of use of the plant (21) with the production of bituminous conglomerates and the simultaneous activation of the damping system (58) of the polluting compounds with the main flame and auxiliary flame which are never active simultaneously can be the following:

M1. Plant (21) and dryer (4) stopped;
M2. Starting of the engines of the transport means (3', 3", 3"') and of the other mechanical transport members such as the elevators or lifting devices (8, 12, 59), that is to say, in general, starting of engines of mechanical transport members (3', 3", 3"', 8, 12, 59) of the plant (21);
M3. Starting of the dryer (4) with the ignition of the at least one burner (5) with the main flame or according to an operating mode in which the burner (5) operates at the third power level;
M4. Enabling the damping system (58) of the polluting compounds;
M5. Activation of the drawing or suction means (23', 23", 23'") of the damping system (58) of the polluting compounds and possible adjustment of the power of the main flame of the at least one burner (5) of the dryer (4), or adjustment of the main flame to operate according to an operating mode in which the burner (5) operates at the greater second power level, carrying out the phases (D1), (D2), (D3), (D4), (D5);
M6. Start of the production of conglomerates;
M7. End of the production of conglomerates;
M8. Waiting for a stop time of the main flame of the burner (5) of the dryer (4);
M9. Main flame of the burner (5) off;
M10. Possible deactivation of the drawing or suction means (23', 23", 23'") of the damping system (58) of the polluting compounds;
M11. Ignition of the additional auxiliary flame of the at least one burner (5) of the dryer (4) for the combustion of the polluting compounds;
M12. Possible re-activation of the drawing or suction means (23', 23", 23"') of the damping system (58) of the polluting compounds in the presence of the additional auxiliary flame for the combustion of the polluting compounds, with the carrying out of the phases (D1), (D2), (D3), (D4), (D5);
M13. Stopping of the plant (21), stopping of the dryer (4) and stopping of the additional auxiliary flame and deactivation of the drawing or suction means (23', 23", 23'") of the damping system (58) of the polluting compounds.

For example a cycle (N) of use of the plant (21) with the production of bituminous conglomerates and the simultaneous activation of the damping system (58) of the polluting compounds with the main flame and auxiliary flame which may be active simultaneously can be the following:

N1. Plant (21) and dryer (4) stopped;
N2. Starting of the engines of the transport means (3', 3", 3"') and of the other mechanical transport members such as the elevators or lifting devices (8, 12, 59), that is to say, in general, starting of engines of mechanical transport members (3', 3", 3"', 8, 12, 59) of the plant (21);
N3. Starting of the dryer (4) with the ignition of the at least one burner (5) with the main flame or according to an operating mode in which the burner (5) operates at the third power level;
N4. Enabling the damping system (58) of the polluting compounds;
N5. Activation of the damping system (58) of the polluting compounds and ignition of the additional auxiliary flame for the combustion of the polluting compounds with the possible adjustment of the main flame;
N6. Start of the production of conglomerates;
N7. Activation of the drawing or suction means (23', 23", 23"') of the damping system (58) of the polluting compounds with the carrying out of the phases (D1), (D2), (D3), (D4), (D5) and with the possible adjustment of the power of said main flame and of said additional auxiliary flame of said at least one burner (5) of said dryer (4);
N8. End of the production of conglomerates;
N9. Waiting for a stop time of the main flame of the at least one burner (5) of the dryer (4);
N10. Main flame of the burner (5) off;
N11. Possible adjustment of the additional auxiliary flame of the at least one burner (5) of the dryer (4) for the combustion of the polluting compounds with the carrying out of the phases (D1), (D2), (D3), (D4), (D5);
N12. Stopping of the plant (21), stopping of the dryer (4) and stopping of the additional auxiliary flame and deactivation of the drawing or suction means (23', 23", 23"') of the damping system (58) of the polluting compounds.

For example a cycle (O) of use of the plant (21) in the absence of production of bituminous conglomerates and with a loading phase of one or more trucks from silos (17) with the only activation of the damping system (58) of the polluting compounds can be the following:

O1. Plant (21) and dryer (4) stopped;
O2. Starting of the mechanical members of feeding of the bituminous conglomerate from one or more storage silos (17);
O3. Enabling the damping system (58) of the polluting compounds and starting of the dryer (4) with ignition of the additional auxiliary flame for the combustion of the polluting compounds;
O4. Activation of the drawing or suction means (23', 23", 23"') of the damping system (58) of the polluting compounds with the carrying out of the phases (D1), (D2), (D3), (D4), (D5) and with the possible adjustment of the power of the additional auxiliary flame of the at least one burner (5) of the dryer (4);
O5. Start of the feeding of bituminous conglomerate from one or more storage silos (17);
O6. End of the feeding of bituminous conglomerate from one or more storage silos (17);
O7. Turning off of the mechanical members of feeding of the bituminous conglomerate from one or more storage silos (17);
O8. Stopping of the dryer (4) and turning off of the additional auxiliary flame for the combustion of the polluting compounds and deactivation of the drawing or suction means (23', 23", 23"') of the damping system (58) of the polluting compounds.

Obviously the cycle (O) of use of the plant in the absence of production of bituminous conglomerates and with a loading phase of one or more trucks from the silos (17) can be integrated in the previously described cycles (M) and (N) because the plant is configured to operate simultaneously the production of new conglomerate to be sent to the silos (17) while one or more loading phases of trucks from the silos (17) occur in the first loading positions (45) or in the second loading positions (46) which are obtained in correspondence of the first transport means (3') of the bituminous conglomerates towards the one or more silos (17) in such a way as to allow for the loading of the transport trucks (22) also during the phases of production and filling of the one or more silos (17).
The suction system (49) of the gases produced in the dryer (4) will have an increased capacity in order to be able to operate an effective suction from the dryer (4) both of the combustion fumes of the burner (5) and of the combustion products due to the combustion of the polluting compounds. The first filter (6) can be a fabric filter, preferably a bag filter.
The adjusting means of the air flow (51), more precisely the deflector or section reducer (54) and the shield (30), which may be present independently of each other or in combination, cause in the air flow (51) which transports the polluting compounds a turbulence and a slowdown, in addition to the previously described deviation of the air flow with respect to the flame and increasing the permanence time in the first chamber (31) or combustion chamber. These combined actions have the purpose of damping the polluting compounds and also any unburnt materials and oils present in the air. In output from the dryer (4) one will ensure an output flow at a temperature compatible with the filter, optionally introducing cooling air to be mixed with that coming out of the dryer (4) or adjusting the power of the burner (5). In this mode the combination of the burner (5) and adjusting means of the air flow (51) eliminates oils and polluting substances from the collected air. The management of a possible excessive temperature at the output of the dryer (4) is preferably entrusted to one or more adjustable cold air intakes, which are installed in the second connection (27") between the dryer (4) and the first filter (6).
With particular reference (Fig. 11, Fig. 12, Fig. 13, Fig. 14) to the structure of the dryer (4) it is preferably made up of a drum (34) which can be made in form of one single rotating drum put in rotation by means of movement means (35) or in the form of a pair of rotating drums comprising a first rotating drum put in rotation by means of first movement means and a second rotating drum put in rotation by means of second movement means. The first rotating drum and the second rotating drum are independently rotating coaxial drums which are arranged one after the other and the first movement means and the second movement means are independent from each other meaning that they can control the rotation of the respective drum at a rotational speed controllable independently with respect to the rotational speed of the other drum. The movement means (35) can be a movement system by friction by means of rollers, for example four rollers, actuated by respective motors or a movement system with a pinion and crown reciprocally engaging for the transmission of the rotational movement. The drum (34), the first drum and the second rotating drum are supported by rollers (36) which contribute to releasing the weight of the respective drum and of its content. The drum (34) is provided with an inlet mouth of the material (37) into which the material (53) to be treated is introduced, which consists of inert materials, preferably inert lithic materials, generally gravel, of varied granulometry and optionally also of recycled material. The material (53) to be treated comes from the first storage means (1) containing the inert materials, preferably inert lithic materials and optionally also from the second storage means (2) containing the recycled conglomerates, according to the operating modes and by means of the previously described devices. Preferably the inlet mouth (37) of the material is provided with first blades or openings (39) which constitute a feeding zone of the material (53), the first blades or openings (39) allowing the material (53) to penetrate the dryer (4) and not allowing it to come out once it has been introduced into the dryer (4). Preferably the inlet mouth (37) of the material is in communication with a third chamber (33) of the dryer (4) which is distinct with respect to the previously described first chamber (31) in which the generation of the flame (50) by the burner (5) occurs. The third chamber (33) is separate with respect to the first chamber (31) by means of second blades or openings (38) having a function similar to the first blades or openings, that is to say, of favouring the entry of the material in the zone where there is the flame (50) and not allowing its return towards the inlet mouth (37) of the material. The material (53) is made to advance thanks (Fig. 11) to fins (40) which can be made in the form of lifting fins, lifting cups or other configurations. The fins (40), which are fixed inside the rotating body of the drum (34) lift the material (53) which is located in the dryer itself and cause its advancement due to the continuous fall of the material (53). One can use fins (40) of different shape along the direction of the flow of material (52) such as larger fins or shaped as a more closed cup in the sections of the drum (34) which are more advanced with respect to the direction of the flow of material (52), that is to say, in the sections of the drum (34) which are further from the inlet mouth (37) of the material. In the sections of the drum (34) which are more advanced there will preferably be fins (40) having such a shape as to lift the material (53) making it advance and preventing the material (53) from falling through the hot combustion gases when the drum is rotated, to obtain a combustion without drawbacks, leaving a free central axial space which is affected by the flame (50).
Any recycled conglomerates, which can be recyclable asphalt products stored in the second storage means (2), are sent to the dryer (4) by means of the third transport means (3"'). Any recycled conglomerates are introduced into the dryer (4) in correspondence of a feeding position which is preferably but not necessarily after the burner with respect to the advancement direction of the material in the dryer, for example by means (Fig. 11) of a feeding device (56) which allows for the feeding of the recyclable asphalt products through circumferential introduction openings (57) which extend annularly to the rotating drum (34) which convey any recycled conglomerates into the rotating drum (34). The introduction of any recycled conglomerates in a feeding position which is located after the burner with respect to the advancement direction of the material in the dryer is advantageous with respect to other positions as the heating of recycled conglomerates containing bitumen would imply further polluting emissions and, therefore, by providing the feeding in this position, one prevents the exposure of the recycled conglomerates containing bitumen to the flame (50), thus preventing the occurrence of further emissions of polluting compounds.
In the second chamber (32) the material (53) which was dried by means of the burner (5) can be optionally impregnated and mixed with bituminous filling substances and binders introduced by means of a lower feeding nozzle (41) which is located behind of the feeding mouth of the flame of the burner (5) in order to prevent the danger of combustion of these substances, the term "behind" referring to the advancement direction of the material inside the dryer (4). The treated material (53) will be discharged downstream by means of a discharge head (42) which is located in correspondence of an opposite end of the dryer (4) with respect to the end of the dryer (4) in correspondence of which there is the inlet mouth (37) of the material to be treated.
As previously explained, the plant (1) and, in general, the damping system (58) can provide different suction positions. As a consequence, the operating method can comprise a suction phase (D1) of the polluting compounds by means of drawing means or suction means (23', 23", 23"') which is a suction phase carried out in correspondence of one or more suction positions selected from:

suction position in correspondence of a loading station (45, 46) of a road transport machine (22). The loading station (45, 46) is provided with first suction means (23') and can be a first loading station (45) or a second loading station (46). The first loading station (45) is a loading station (45) from one or more storage silos (17) for storing the conglomerates. The second loading station (46) is obtained in the first transport means (3') of the bituminous conglomerates towards the one or more silos (17), in said second loading station (46) occurring a sending phase of a part of the bituminous conglomerates which advance on the transport means (3') towards the second loading station (46) of the road transport machines (22);
suction position in correspondence a cover hood of the first transport means (3') which perform the transport of the bituminous conglomerates towards the one or more storage silos (17), said cover hood being provided with second suction means (23");
suction position in correspondence of one or more devices for the production of the bituminous conglomerates of the mixing section (28), said mixing section (28) being provided with third suction means (23'").

With particular reference to the suction position in correspondence of the loading station (45, 46) of the road transport machines (22), which is provided with the first suction means (23'), said suction position can be made in form of a room (24) into which the road transport machines (22) can enter to be loaded, said room (24) preferably being essentially air-tight in such a way that the room (24) is kept in depression by means of the first suction means (23'). In general the eco-friendly plant for the production and distribution of bituminous conglomerates comprises:

at least one dryer (4) of inert materials (53), preferably inert lithic materials;
a mixing section (28) for mixing with a binder, preferably bitumen, obtaining said bituminous conglomerates;
first transport means (3') of the bituminous conglomerates from the mixing section (28) to at least one storage silo (17) for storing the bituminous conglomerates;
at least one loading station (45, 46) of a road transport machine (22), said loading station (45, 46) being a loading station with the bituminous conglomerates coming from the plant (21) or from the silos (17).

The dryer (4) is provided with at least one burner (5) generating drying heat for the materials (53) and is provided with a suction system (49) of air from the dryer (4).
The plant (21) or the dryer (4) can be configured and structured to operate in accordance with the previously described operating method.
The plant (21) or the dryer (4) further comprise a damping system (58) of polluting compounds which are generated in the plant (21), said damping system (58) of polluting compounds comprising:

drawing means or suction means (23', 23", 23'") of the polluting compounds, said drawing means or suction means (23', 23", 23"') being located in correspondence of at least one emission position of the polluting compounds;
at least one first connection (27') connecting the drawing means or suction means (23', 23", 23'") to the dryer (4), said at least one first connection (27') conveying the polluting compounds towards the dryer (4).

The dryer (4) is further provided with:

an entry (43) connected to the first connection (27'), said entry (43) introducing the polluting compounds into the dryer (4);
deviation means (30, 54) of the air flow (51) containing the polluting compounds towards the at least one flame (50) generated by the at least one burner (5), said at least one flame (50) causing a combustion of the polluting compounds.

The arrangements of the plants shown in the figures are purely indicative and are provided as an illustrative and non-exhaustive example for the purposes of the present invention.
The description of the present invention has been made with reference to the enclosed figures in a preferred embodiment, but it is evident that many possible changes, modifications and variations will be immediately clear to those skilled in the art in the light of the previous description. Thus, it must be underlined that the invention is not limited to the previous description, but it includes all the changes, modifications and variations in accordance with the appended claims.

Nomenclature used

With reference to the identification numbers in the enclosed figures, the following nomenclature has been used:

1'. First storage means
2. Second storage means
3'. First transport means
3". Second transport means
3"'. Third transport means
4. Dryer
5. Burner
6. First filter
7. Container
8. First elevator or elevator of inert materials
9. Screen
10. Buffer means or hoppers under the screen
11. First weighing means
12. Second elevator or elevator of the filler
13. Second weighing means
14. Mixer
15. Boiler
16. Tank
17. Silo
18. Control unit
19. Hopper under the filter
20. Screw device
21. Plant
22. Truck or road transport machine
23'. First drawing or suction means
23". Second drawing or suction means
23"'. Third drawing or suction means
24. Room
25. Second filter
26. Fan
27'. First connection
27". Second connection
28. Mixing tower or section
29. Fume exhaust means
30. Shield
31. First chamber
32. Second chamber
33. Third chamber
34. Drum
35. Movement means
36. Roller
37. Inlet mouth of the material
38. Second blade or opening
39. First blade or opening
40. Fin or advancing means
41. Nozzle or feeding means
42. Discharge head
43. Entry
44. Exit
45. First loading station
46. Second loading station
47. Heap
48. Sieve
49. Suction system
50. Flame
51. Air flow
52. Flow of material
53. Material
54. Deflector or section reducer
55. Opening
56. Feeding device
57. Circumferential opening
58. Damping system
59. Fine dust lifting device

Claims

Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates comprising:
- at least one inlet mouth (37) for inert materials (53), preferably inert lithic materials;

- at least one burner (5) generating at least one flame (50) which generates drying heat for said materials (53);

- at least one discharge head (42) for the extraction of said materials (53) from said dryer (4);

- attachment means in the form of an exit (44) from which the air is recovered suitable for connection to a suction system (49) of air adapted to suck air from said dryer (4);
characterised in that
said dryer (4) is provided with connecting means for the connection to a damping system (58) of polluting compounds which are generated in said plant (21), said damping system (58) of polluting compounds comprising:
- generation means (23', 23", 23"', 26) of an air flow (51) containing said polluting compounds which are drawn from said plant (21);

- introduction means (27', 43) of said air flow (51) containing the polluting compounds inside said dryer (4); said dryer (4) comprising:

- deviation means (30, 54) of said air flow (51) containing the polluting compounds which are configured to deviate said air flow (51) towards a perimetrically external surface or shell of said dryer (4), said deviation means (30, 54) being configured and structured to spread apart said air flow (51) at least from a generation zone of the at least one flame (50) and said deviation means (30, 54) being configured and structured to generate a turbulence in said air flow (51) increasing the permanence time of said polluting compounds inside said dryer (4);
wherein said at least one flame (50) causes a combustion of said polluting compounds.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim, characterised in that said generation means (23', 23", 23"', 26) of said air flow (51) containing said polluting compounds include drawing means or suction means (23', 23", 23"') of said polluting compounds, said drawing means or suction means (23', 23", 23"') being located in correspondence of at least one emission position of said polluting compounds of said plant (21).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim, characterised in that said introduction means (27', 43) of said air flow (51) containing the polluting compounds inside said dryer (4) include at least one first connection (27') connecting said drawing means or suction means (23', 23", 23"') to said dryer (4) in correspondence of an entry (43) of said dryer (4), said entry (43) introducing said polluting compounds into said dryer (4) by means of said air flow (51).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that said deviation means (30, 54) of said air flow (51) containing the polluting compounds towards said at least one flame (50) are configured and structured to convey said polluting compounds according to a conveying direction which is oriented in a way concordant with a direction according to which said at least one flame (50) is oriented.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that it comprises adjusting means for adjusting the combustion temperature of said polluting compounds by means of said at least one flame (50), said combustion temperature being higher than 400°C, preferably higher than 600° C.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that said deviation means (30, 54) are selected from one or more of the following:
- a deflector or section reducer (54) preferably made of refractory steel, which facilitates the restraint of the air flow (51) with the polluting compounds in a first chamber (31) or combustion chamber of said dryer (4) and which also facilitates the establishment of a turbulent motion, said deflector or section reducer (54) being configured to encumber the exit of said air flow (51) from said first chamber (31);

- a shield (30) of the air flow (51) which is configured and structured to deviate the air flow (51) with the polluting compounds in such a way that the air flow (51) is directed according to an advancement direction which is essentially oriented towards the zone of the at least one flame (50) in which the temperature of the flame itself is greater, that is to say, essentially in such a way that the air flow (51) is directed towards the external part of the at least one flame (50).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim, characterised in that it comprises both said deflector or section reducer (54) and said shield (30) which are spaced from each other and face each other, said shield (30) being essentially located around said burner (5) in such a way as to surround at least one initial part of said flame (50) and said deflector or section reducer (54) being located in an advanced position with respect to said shield (30), the term advanced position referring to the advancement direction of the air flow (51), said deflector or section reducer (54) being located near a zone of said dryer (4) essentially corresponding to an end zone of the development of said flame (50).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 6 to 7, characterised in that said deflector or section reducer (54) has an essentially frustoconical shape, said frustoconical shape being arranged with an enlargement direction of the frustoconical shape oriented according to a concordant orientation with respect to the advancement direction of said air flow (51) inside said dryer (4).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 6 to 8, characterised in that said shield (30) has an essentially frustoconical shape, said frustoconical shape being arranged with an enlargement direction of the frustoconical shape oriented according to a concordant orientation with respect to the advancement direction of said air flow (51) inside said dryer (4).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that said generation means (23', 23", 23"', 26) of said air flow (51) are configured and structured to adjust said air flow (51) obtaining an air flow (51) in a range from about 1000 to about 20000 Nm3/h 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 equal to 1 atmosphere and 20°C respectively.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that it comprises adjusting means for adjusting the internal pressure of said dryer (4), said adjusting means adjusting the pressure inside said dryer in such a way as to keep a depression condition on an essentially constant value which is determined depending on process parameters selected from temperature inside said dryer (4), air flow inside said dryer (4), quantity of said material (53) inside said dryer (4), recipe for preparing said bituminous conglomerates, humidity of said material (53).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that it comprises adjusting or switching means of the operating power of said at least one burner (5) between at least two different power levels, a first power level of which having a lower operating power with respect to the operating power of a second power level, wherein:
- said first power level is such as to cause said combustion of said polluting compounds in the absence of said materials (53) inside said dryer (4);

- said second power level is such as to cause said combustion of said polluting compounds in the presence of said materials (53) inside said dryer (4).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim, characterised in that the power of said first power level is between about 1/6 and 1/3 of the power of the second power level, preferably the power of said first power level being between about 1/5 and 1/4 of the power of the second power level.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 12 to 13, characterised in that the power of said first power level is between 1.5 and 8.5 MW, preferably between 2 and 7 MW, even more preferably between about 2.5 and about 3.5 MW or characterised in that the power of said second power level is between 9 and 25 MW, preferably between 12 and 22 MW, even more preferably between about 14 and about 18 MW, for a production rate of about 200 tons/hour of conglomerate.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 12 to 14, characterised in that it comprises adjusting or switching means of the operating power of said at least one burner (5) between at least three different power levels, of which said first power level having a lower operating power with respect to the operating power of said second power level, and furthermore a third power level between said first power level and said second power level, said third power level being such as to cause only said drying of said materials (53) in a disabled condition of said damping system (58) of polluting compounds.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim, characterised in that the power of said third power level is between about 2/3 and 3/3 of the power of the second power level.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 15 to 16, characterised in that the power of said third power level is between 6 and 22 MW, preferably between 8 and 20 MW, even more preferably between about 10 and about 18 MW, for a production rate of about 200 tons/hour of conglomerate.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that said at least one burner (5) is a single burner having a variable power.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim and according to any of the previous claims 12 to 17, characterised in that it comprises adjusting means for adjusting the operating power of said single burner having a variable power between said different power levels.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 1 to 17, characterised in that said at least one burner (5) consists of at least two different burners or of two different stages of which:
- a first burner or a first stage constitutes an auxiliary burner generating a first flame or auxiliary flame;

- a second burner or a second stage constitutes a main burner generating a second flame or main flame.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim and according to any of the previous claims 12 to 17, characterised in that said auxiliary burner is configured and structured to operate at said first power level or characterised in that said main burner is configured and structured to operate at said second power level.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 20 to 21, characterised in that said main burner and said auxiliary burner are configured to operate alternatively with respect to each other.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 20 to 21, characterised in that said main burner and said auxiliary burner are configured to operate simultaneously or autonomously with respect to each other.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that said drawing means or suction means (23', 23", 23'") are located in correspondence of one or more suction positions selected from:
- suction position in correspondence of a loading station (45, 46) of one or more road transport machines (22) provided with first drawing or suction means (23'), said loading station (45, 46) being a first loading station (45) or a second loading station (46), wherein said first loading station (45) is a loading station (45) from one or more storage silos (17) for storing the conglomerates, wherein said second loading station (46) is obtained in correspondence of first transport means (3') of the bituminous conglomerates from a mixing section (28) connected to said dryer (4) towards the one or more silos (17), said second loading station (46) comprising means for sending a part of bituminous conglomerates which advance on said transport means (3') towards said second loading station (46) of one of said road transport machines (22);

- suction position in correspondence of a cover hood of said first transport means (3') which perform the transport of the bituminous conglomerates towards the one or more storage silos (17), said cover hood being provided with second drawing or suction means (23");

- suction position in correspondence of one or more devices for the production of the bituminous conglomerates of said mixing section (28), said mixing section (28) being provided with third drawing or suction means (23"').
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim, characterised in that said suction position in correspondence of said loading station (45, 46) of one of said road transport machines (22), which is provided with first drawing or suction means (23'), is made in the form of a room (24) into which one of said road transport machines (22) can enter to be loaded, said room (24) preferably being an essentially air-tight room in such a way that said room (24) is kept in depression by means of said first drawing or suction means (23').
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that it comprises a first filter (6) connected to said dryer (4) by means of a second connection (27"), said first filter (6) being preferably a dust exhaust first filter (6) which is provided with a hopper (19) for recovering the filtered dusts.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 2 to 26, characterised in that said generation means (23', 23", 23"', 26) of said air flow (51) containing said polluting compounds comprise at least one fan (26) connected to said drawing means or suction means (23', 23", 23'"), said fan (26) being coupled with a second filter (25) which is located upstream with respect to it and with respect to the air flow containing the drawn or sucked polluting compounds, said second filter being preferably a separating filter having sectors of pre-treatment of the sucked air containing the polluting compounds, said second filter (25) filtering particles or oils contained in the air flow.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that said dryer (4) comprises a second chamber (32), said entry (43) connected to said first connection (27') being in flow communication with said second chamber (32), said second chamber (32) constituting a pre-introduction chamber for said air flow (51).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims 6 to 28, characterised in that said dryer (4) also comprises a third chamber (33) which is provided with an inlet mouth (37) of the material, said third chamber (33) being in communication with said first chamber (31) in which said flame (50) is generated by the burner (5), said inlet mouth (37) of the material being preferably provided with first blades or openings (39) which constitute a feeding zone of the material (53), said first blades or openings (39) allowing the material (53) to enter the dryer (4) and not allowing it to come out once it has been introduced into the dryer (4), said third chamber (33) being preferably separate from said first chamber (31) by means of second blades or openings (38) which are shaped and structured to facilitate the entry of the material in the first chamber (31) and encumber its return towards the inlet mouth (37) of the material.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim, characterised in that said deflector or section reducer (54) is located between said first chamber (31) and said third chamber (33) of the dryer (4).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, characterised in that said dryer (4) is made up of:
- a rotating drum (34) which is put in rotation by means of movement means (35);
or

- a pair of rotating drums comprising a first rotating drum which is put in rotation by means of first movement means and a second rotating drum which is put in rotation by means of second movement means, preferably in the form of a pair of independently rotating coaxial drums which are controllable in an independent way with respect to each other by means of said first movement means and said second movement means.
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to any of the previous claims, said dryer (4) being configured and structured to operate according to an operating method, wherein said operating method of said dryer (4) operates according to at least the following operating cycle:
(i) operating cycle of drying of bituminous conglomerates, said operating cycle of drying of bituminous conglomerates comprising at least the following phases:
(A1) feeding of at least inert materials (53), preferably inert lithic materials, in correspondence of said inlet mouth (37) of said dryer (4);

(A2) ignition of said at least one burner (5) generating drying heat for said inert materials (53) and turning on of said at least one suction system (49) of air from said dryer (4);

(A3) drying of said materials (53) inside said dryer (4) in a condition in which said materials (53) are exposed to said drying heat and advancement of said materials (53) inside said dryer (4) according to an advancement direction of the flow (52) of material;

(A4) possible introduction of recycled conglomerates in said dryer (4);

(A5) possible introduction of filling bituminous substances and binders in said dryer (4) by means of feeding means (41);

(A6) extraction of said materials (53) in correspondence of a discharge head (42) of said dryer (4);
characterised in that said operating method of said dryer (4) also comprises a damping phase of polluting compounds which are generated in said plant (21), said damping phase comprising the following sub-phases:
(D1) suction or drawing of said polluting compounds by means of said drawing means or suction means (23, 23", 23"') which are located in correspondence of at least one emission position of said polluting compounds;

(D2) transport of said drawn or sucked polluting compounds towards said dryer (4) by means of said at least one first connection (27');

(D3) introduction of said drawn or sucked polluting compounds in said dryer (4) by means of said air flow (51);

(D4) conveying of said drawn or sucked polluting compounds towards said at least one flame (50) generated by said at least one burner (5);

(D5) combustion of said polluting compounds by means of said at least one flame (50).
Dryer (4) for a plant (21) for the production and distribution of bituminous conglomerates according to the previous claim, characterised in that said operating method of said dryer (4) also comprises a slowdown phase of the speed of said air flow (51), said slowdown of the speed of said air flow (51) causing an increase in the permanence time of said volatile organic compounds inside said dryer (4), said permanence time of said volatile organic compounds inside said dryer (4) being preferably in a range between 1 and 5 seconds, even more preferably in a range between 1.5 and 2 seconds.
Eco-friendly plant (21) for the production and distribution of bituminous conglomerates comprising:
- at least one dryer (4) of inert materials (53), preferably inert lithic materials;

- a mixing section (28) for mixing with a binder obtaining said bituminous conglomerates;

- first transport means (3') of said bituminous conglomerates from said mixing section (28) to at least one storage silo (17) for storing said bituminous conglomerates;

- at least one loading station (45, 46) of a road transport machine (22), said loading station (45, 46) being a loading station of said bituminous conglomerates from said plant (21) or from said at least one storage silo (17);
characterised in that said dryer (4) is made according to any of the previous claims.