Dryer

Abstract

The invention describes a dryer comprising: a drying cylinder (2) rotating about its own main extension axis (R2); a loading head (3) at a first end (2a) of the drying cylinder for introducing the raw inert stone material into the drying cylinder; an unloading head (4) located at a second end (2b) of the drying cylinder; a burner (8) for generating a flame (9) in the combustion chamber (7) and generating a first dry flow (F9) in the drying chamber (6); feeding means (11) downstream of the combustion chamber (7) and upstream of the unloading head (4) for introducing recycled asphalt material into the drying cartridge; the drying cartridge comprises a drying chamber (12) downstream of the feeding device (11) and upstream of the unloading head and a combustion chamber (13) downstream of the drying chamber (12) and upstream of the unloading head, and the dryer comprises a system for generating a second flow of drying gas (F15) in the second drying chamber (12).

Description

Field of the Invention

[0001] The present invention relates to a dryer for an industrial plant for producing a mixture in the form of macadam with an asphalt binder and a non-asphalt binder (also known as bituminous macadam), said mixture being in particular designed to form a road surface. Background Art

[0002] In the field of industrial plants for producing bituminous macadam, there are widespread plants that allow the use in the mixture of virgin inert stony materials (such as gravel, hereinafter also simply referred to as virgin materials) as well as recycled or reclaimed materials (Recycled Asphalt Pavement i.e. RAP), for example originating from the milling of existing road surfaces.

[0003] Both virgin materials and recycled materials must be in a predetermined physical condition for mixing (for example, hot and dry), so they are also thermally treated in the plants of interest.

[0004] All materials are then processed in a suitable dryer, for example to condition the humidity, and introduced into a hopper from which they are taken to form the desired final mixture.

[0005] The patent document EP3221517 in the name of the same applicant as the present invention shows a plant for producing and distributing bituminous macadam, which includes a countercurrent dryer (the material to be dried moves in the drum in a direction opposite to the flow of hot drying air), said countercurrent dryer being equipped with a single burner for drying the material to be processed (virgin and recycled).

[0006] The dryer schematically includes a burner and a rotating drum, and the flame generated by the burner is guided inside the rotating drum, thus determining a combustion chamber.

[0007] The drum is provided with an inlet opening for the virgin material and a feeding device, which is located downstream of the combustion chamber in the feeding direction of the virgin material, for introducing any recycled macadam.

[0008] The unloading head located at the end of the drum opposite to the feeding opening for the virgin material allows the virgin material and the recycled material to be discharged after being processed.

[0009] According to the feeding direction of the material in the dryer, it is necessary to introduce the recycled macadam into a feeding position located after the combustion chamber, in particular downstream of the burner flame, because the overheating of the recycled macadam containing asphalt by the flame would cause a large amount of pollutant emissions.

[0010] Feeding the recycled material downstream of the combustion chamber avoids exposing the recycled macadam containing asphalt to the burner flame and also prevents the occurrence of further emissions of pollutant compounds.

[0011] The main drawback of this prior art solution is that the recycled material introduced into the dryer can reach up to 35%-40% of the total amount of the processed material.

[0012] In fact, due to the above reasons, the recycled material is not heated, thus reducing the temperature of the raw material mixed with them before the unloading head, and consequently reducing the temperature of the mixture flowing out of the dryer.

[0013] Since the temperature of the mixture at the discharge section must be 160°, the feeding of an excessive amount of recycled material will not allow this condition to be met, while the main requirement in this field is to use an increasingly large ratio of recycled material while reducing the emissions of pollutant compounds.

[0014] In this context, the aim is to propose a dryer that can overcome at least some of the drawbacks of the prior art and meet the above requirements. Summary of the Invention

[0015] In particular, the aim of the present invention is to provide a dryer that allows an increase in the ratio of recycled material containing pollutant emissions in the mixture.

[0016] This aim is achieved by a dryer comprising the technical features described in one or more of the appended claims. The dependent claims correspond to possible different embodiments of the present invention.

[0017] According to a first aspect, the present invention relates to a dryer for an industrial plant for the production of asphalt macadam.

[0018] The dryer, described only to the extent necessary for understanding the present invention, comprises a drying drum that rotates about its own main extension axis.

[0019] The dryer comprises a loading head located at a first end of the drying drum for introducing a first material into the drying drum.

[0020] Preferably, the first material is a raw inert stony material.

[0021] The dryer comprises an unloading head located at a second end of the drying drum.

[0022] The dryer comprises a feeding system for feeding the first material from the loading head to the unloading head in a feeding direction.

[0023] The drying drum comprises a first drying chamber and a first combustion chamber located downstream of the first drying chamber according to the feeding direction of the first material.

[0024] The dryer comprises a first burner located at the second end for generating a first flame in the first combustion chamber and a first drying flow in the first drying chamber.

[0025] The first burner includes a feed pipe for feeding fuel into the first flame in the first combustion chamber.

[0026] Preferably, the power of the first burner is between 9 MW and 30 MW.

[0027] The first drying stream moves in a direction opposite to the feeding direction of the first material, so the dryer is a countercurrent type dryer.

[0028] The dryer includes a feeding device, which is located downstream of the first combustion chamber and upstream of the unloading head in the feeding direction, for introducing a second material into the drying cylinder; the second material is preferably a recycled asphalt material.

[0029] The feeding system is configured to feed a mixture of the first material and the second material, in particular a mixture of raw inert stony material and recycled asphalt material, downstream of the feeding device until the unloading head.

[0030] The feeding direction is the same for the first material and the second material downstream of the feeding device.

[0031] According to the feeding direction of the first material and the second material, the drying cylinder includes a second drying chamber downstream of the feeding system and upstream of the unloading head.

[0032] Preferably, the pipe for feeding the first burner passes through the second drying chamber for feeding fuel into the first flame in the first combustion chamber.

[0033] The dryer includes a system for generating a drying gas stream (such as including hot air) for generating a second drying gas stream in the second drying chamber.

[0034] The second drying gas stream moves in a direction opposite to the feeding direction of the first material and flows countercurrently with respect to the mixture of the first material and the second material.

[0035] The temperature of the second drying gas stream is lower than the temperature of the first drying gas stream.

[0036] The system for generating the second drying stream may include a second combustion chamber in the drying cylinder.

[0037] According to the feeding direction of the first material and the second material, the second combustion chamber is located downstream of the second drying chamber and upstream of the unloading head.

[0038] The dryer includes at least one second burner with a power less than that of the first burner for generating a second flame in the second combustion chamber and at least generating a second drying gas stream in the second drying chamber.

[0039] Preferably, the power of the second burner is between 0.5 MW and 4 MW.

[0040] Preferably, the second burner is located at the second end of the drying cylinder.

[0041] Preferably, the dryer includes a third burner that generates a third flame in the second combustion chamber. The combined second and third flames determine the second drying gas stream.

[0042] Preferably, the second burner and the third burner have the same power.

[0043] Preferably, the third burner is located at the second end of the drying cylinder.

[0044] Preferably, the pipe for feeding the first burner passes through the second combustion chamber and the second drying chamber for feeding fuel to the first flame in the first combustion chamber.

[0045] Preferably, the dryer includes a tubular protective member for the feed pipe.

[0046] Preferably, the feed pipe passes through the tubular protective member, that is, it is inserted into the tubular protective member.

[0047] Preferably, the tubular protective member extends through the second combustion chamber and the second drying chamber.

[0048] Preferably, the tubular protective member is fixed to the drying cylinder and rotates with the drying cylinder.

[0049] The system for generating the second drying gas stream may include a hot air generator of a substantially known type in communication with the second drying chamber, the hot air generator being for generating hot air and feeding the second drying gas stream thereto.

[0050] Preferably, the hot air generator is located outside the drying cylinder and is preferably connected to the discharge head.

[0051] Preferably, the system for feeding material into the drying cylinder includes comb-like vanes fixed to the inner surface of the drying cylinder at the second drying chamber.

[0052] Preferably, the feed system includes a plurality of refractory plates at the second combustion chamber for protecting the base of the dryer so as to protect it from wear due to friction.

[0053] Advantageously, the protective refractory plates avoid the lifting of the material (the material thus slides forward on the bottom for feeding), prevent the mixture of the first material and the second material from being affected by the second flame and / or the third flame, and prevent the recycled asphalt material from releasing pollutant emissions due to the combustion of asphalt.

[0054] Preferably, the ratio between the total length of the first drying chamber and the first combustion chamber measured along the main extension axis of the drying drum and the total length of the second drying chamber and the second combustion chamber measured along the main extension axis of the drying drum is between 1.5 and 2.5.

[0055] Preferably, the ratio between the length of the second drying chamber measured along the main extension axis of the drying drum and the length of the second combustion chamber measured along the main extension axis of the drying drum is between 1 and 4.

[0056] In fact, compared with traditional dryers, the dryer according to the present invention is elongated downstream of the feeding device, because the drum includes a second drying chamber before the unloading head and, if necessary, a second combustion chamber before the unloading head, so that the mixture of raw materials and RAP can be further dried and thus heated with a second drying stream.

[0057] According to one aspect, the present invention relates to a method for drying raw inert stony materials and recycled asphalt materials.

[0058] The method comprises: introducing the raw inert stony materials into a dryer; heating the raw inert stony materials with a first drying gas stream having a first temperature and generated by a first flame; mixing the heated raw inert stony materials with the recycled asphalt materials to obtain a mixture; heating the mixture with a second drying gas stream having a second temperature lower than the first temperature; unloading the mixture heated by the dryer.

[0059] The second drying gas stream can be generated by a second flame inside the dryer.

[0060] The second drying gas stream can be generated by a hot air generator outside the dryer and introduced into the dryer.

[0061] Preferably, the dryer is the dryer of an industrial plant for asphalt macadam according to the foregoing aspect.

[0062] The dryer according to the above aspect brings important advantages.

[0063] The second drying chamber located downstream of the device for feeding the recycled asphalt materials allows the temperature of the mixture to be increased.

[0064] Compared with traditional dryers (such as the dryer described in the patent document EP3221517), a larger amount of recycled asphalt materials can be added to the raw stony materials in the case of the same temperature of the mixture and the same temperature of the raw materials, because the mixture that has experienced a large temperature drop is subsequently heated in the second drying chamber before unloading.

[0065] The applicant has observed that with the dryer according to the present invention, the percentage of RAP can reach up to 60% of the weight of the mixture.

[0066] In the same way, due to the subsequent heating of the mixture, the heating of the raw materials can be reduced.

[0067] Compared with the first drying gas stream, the temperature of the second drying gas stream is reduced in order to limit the temperature rise of the RAP so that no pollutant compounds are produced, but is sufficient to bring the temperature of the mixture to the desired value at the discharge section, which is necessary for subsequent processing in an installation for the production of asphalt macadam.

[0068] Advantageously, when a second combustion chamber is provided, the gases produced in the second combustion chamber are conveyed to the first combustion chamber having the property of heat-treating any pollutant compounds, such as described in the patent document EP3221517. The Applicant has observed that by using the dryer according to the invention, pollutant emissions can be controlled below 50 mg / Nm3 of VOC.

[0069] Advantageously, the flue gases leaving the dryer according to the invention have a lower temperature than the prior art solutions.

[0070] Compared with the dryers of the prior art, the dryer according to the invention allows a reduction in the emissions of pollutant compounds.

[0071] Advantageously, the dryer according to the invention allows a better distribution of heat inside the dryer, thus increasing the efficiency.

[0072] Advantageously, the dryer according to the invention also allows a reduction in the odours released at the outlet by heating the RAP in a more gradual manner by conduction and convection.

[0073] The additional features and advantages of the above aspects are more apparent in the following non-limiting description of a preferred non-limiting embodiment of a dryer for an industrial installation for the production of asphalt macadam. Description of the Drawings

[0074] The following description is set forth with reference to the drawings, which are provided solely for purposes of illustration and do not limit the scope of the invention, and in which:

[0075] Figure 1 is a schematic side view of a dryer according to the invention;

[0076] Figure 2 shows Figure 1 a schematic cross-sectional view of the dryer, in which some parts have been removed for greater clarity;

[0077] Figure 3 shows Figure 1 and Figure 2 a side view of the dryer, in which some parts have been cut away for greater clarity;

[0078] Figure 4 shows Figure 1 a schematic sectional perspective view of the details of a dryer;

[0079] Figure 5 shows Figure 1 of the dryer through Figure 1 a schematic sectional view of plane 5-5;

[0080] Figure 6 shows in a schematic perspective view Figure 1 the details of a dryer;

[0081] Figure 7 shows a schematic side view of a dryer according to the present invention, in which some parts are cut away for clarity. Detailed description

[0082] Referring to the drawings, the numeral 1 denotes the entire dryer according to the present invention.

[0083] The dryer 1 is designed for an industrial plant (not shown) for producing asphalt macadam.

[0084] Schematically, as described in more detail below, the dryer 1 is specifically designed to condition a mixture of virgin inert stony material (e.g., gravel) and recycled or reclaimed material (recycled asphalt pavement, RAP), said recycled or reclaimed material being, for example, derived from the milling of existing road surfaces.

[0085] Figure 1 and Figure 2 Also schematically shown is a frame 100 for supporting the dryer 1.

[0086] The dryer 1 includes a drying drum 2 that rotates about its own main extension axis R2.

[0087] The dryer includes a loading head 3 located at a first end 2a of the drying drum 2.

[0088] The loading head 3 is for introducing a first material (preferably virgin inert stony material) into the drying drum 2.

[0089] The dryer 1 includes an unloading head 4 located at a second end 2b of the drying drum 2, from which a mixture of virgin inert stony material and RAP can be unloaded.

[0090] The dryer 1 includes a feed or conveying system 5 for feeding the material from the loading head 3 to the unloading head 4 in a feed direction V.

[0091] The feed system 5 is schematically based on the rotation of the drying drum 2 and on the inclination of the drying drum 2 (at Figure 1 andFigure 2 It can be seen that there is a slope between the loading head 3 and the unloading head 4), and it is based on a specific device provided in the inner surface of the drum 2.

[0092] Schematically, the geometry of the device, the inclination and the rotational speed of the drum determine the travel time of the material from the loading head 3 to the unloading head 4.

[0093] The drying drum 2 includes a first drying chamber 6 and a first combustion chamber 7 located downstream of the first drying chamber 6 according to the feed direction V of the first material.

[0094] The dryer 1 includes a first burner 8 of a substantially known type located at the second end 2b of the drying drum 2 for generating a first flame 9 in the first combustion chamber 7 and generating a first drying gas stream F9, i.e., hot air, in the first drying chamber 6.

[0095] The first burner 8 includes a feed pipe 10 for feeding fuel to the first flame 9 in the first combustion chamber 7.

[0096] The feed pipe 10 extends from the head 4 into the first combustion chamber 7 within the drying drum 2.

[0097] Preferably, the power of the first burner 8 is between 9 MW and 30 MW.

[0098] The dryer 1 includes a feed device 11 which, along the feed direction V, is located downstream of the first combustion chamber 7 and upstream of the unloading head 4.

[0099] The feed device 11 is arranged and configured to introduce a second material (preferably a recycled asphalt material) into the drying drum 2.

[0100] The feed system 5 is configured to feed the mixture of the above-mentioned original inert stony material and RAP included within the drying drum 2 downstream of the feed device 11 until the unloading head 4.

[0101] In fact, the system and the feed direction V are common for the first material and the second material downstream of the feed device 11.

[0102] The drying drum 2 includes a second drying chamber 12 which is located downstream of the feed system 11 and upstream of the unloading head 4 in the feed direction V of the mixture of the first material and the second material.

[0103] The dryer includes a system for generating a drying gas stream of a substantially known type, which is represented as a whole by the number 25.

[0104] The system 25 is configured to generate a second drying gas stream F15, i.e., hot air, in the second drying chamber 12.

[0105] According toFigures 1 to 6 In the illustrated embodiment, the system 25 includes a second combustion chamber 13 in the drying cylinder 2.

[0106] According to the feed direction V of the mixture of the first material and the second material, the second combustion chamber 13 is located downstream of the second drying chamber 12 and upstream of the unloading head 4.

[0107] According to the illustrated embodiment, the total length L6+L7 of the first drying chamber 6 and the first combustion chamber 7 measured along the axis R2 is equal to 10 m, the length L12 of the second drying chamber 12 measured along the axis R2 is 3.5 m, and the length L13 of the second combustion chamber 13 measured along the axis R2 is equal to 2 m.

[0108] Preferably, the ratio of the total length L6+L7 of the first drying chamber 6 and the first combustion chamber 7 measured along the axis R2 to the total length L12+L13 of the second drying chamber 12 and the second combustion chamber 13 is between 1.5 and 2.5.

[0109] Preferably, the ratio of the length L12 of the second drying chamber 12 to the length L13 of the second combustion chamber 13 is between 1 and 4.

[0110] The dryer 1 includes at least one second burner 14 with a power less than that of the first burner 8, for generating a second flame 15 in the second combustion chamber 13 and at least generating a second drying gas flow F15 in the second drying chamber 12.

[0111] Preferably, the power of the second burner 14 is between 0.5 MW and 4 MW.

[0112] According to the illustrated embodiment, the second burner is substantially located at the second end 2b of the drying cylinder 2.

[0113] Preferably, the dryer includes a third burner 16 for generating a third flame 17 in the second combustion chamber. The combined second flame 15 and third flame 17 determine the second drying gas flow F15.

[0114] Generally, the dryer according to the present invention may include any number of burners in the second combustion chamber 13 based on design requirements, especially according to the expected second drying gas flow F15.

[0115] Preferably, the third burner 16 has the same power as the second burner 14.

[0116] Preferably, the third burner 16 is located at the second end 2b of the drying cylinder.

[0117] According to Figure 5In the exemplary embodiment shown, the second burner 14 and the third burner 16 are arranged symmetrically with respect to a vertical plane (with reference to the attached drawings, this vertical plane passes through the axis R2) to obtain as uniform a drying flow F15 as possible in the second drying chamber 12.

[0118] Generally speaking, the second burner 14 and the third burner 16 are preferably positioned so as not to interact with the material in the cylinder 2.

[0119] According to a preferred embodiment not shown, the second burner 14 and the third burner 16 are located on a plane inclined with respect to the vertical plane.

[0120] According to a preferred embodiment not shown, the second burner 14 and the third burner 16 are asymmetrically located in the drying cylinder 2. The second burner 14 and the third burner 16 are located in the dryer 1 according to the available installation space.

[0121] According to Figure 7 the embodiment schematically shown in, the system 25 for generating the second drying gas flow F15 includes a hot air generator 26 of a generally known type.

[0122] The hot air generator 26 communicates with the second drying chamber 12 for feeding the second drying gas flow F15 therein.

[0123] The hot air generator 26 is located outside the drying cylinder 2 and is connected to the unloading head 4.

[0124] According to an alternative embodiment not shown, the hot air generator 26 can be separated from the drying cylinder 2.

[0125] The dryer 1 includes a ventilation system for introducing air from a mixing device, which is usually provided in an industrial plant for producing bituminous macadam, into the dryer 1, particularly into the drying cylinder 2. The dryer 1 is maintained under negative pressure by a dust separation filter in a known manner, and this dust separation filter is usually also provided in an industrial plant for producing bituminous macadam.

[0126] The ventilation system includes a fan for generating the flow F30, which is schematically represented as a box 30 in Figure 3 the figure.

[0127] According to the preferred embodiment shown, the flow F30 is between 2000 m3 / h and 6000 m3 / h.

[0128] The dryer 1 includes a system for discharging flue gas, labeled 18, of a generally known type, and this system also includes at least one filter and a flue (not shown). The drying gas flows F15 and F9 are combined in chambers 6 and 7 and reach the discharge system 18.

[0129] As shown, the pipe 10 for feeding the first burner 8 passes through the second drying chamber 12 and, if present, through the second combustion chamber 13.

[0130] The dryer 1 includes a tubular protection member 19 for the feed pipe 10. Preferably, the tubular protection member 19 is coaxial with the drying cylinder 2.

[0131] According to the illustrated embodiment, the tubular protection member 19 is fixed to the drying cylinder 2, for example, by an arm 20 and rotates therewith.

[0132] The tubular protection member 19 is inserted into and passes through the second drying chamber 12 and the second combustion chamber 13.

[0133] The feed pipe 10 is inserted into and passes through the tubular protection member 19.

[0134] The tubular protection member 19 protects the feed pipe 10 from the mixture of virgin material and RAP material that can move within the drying cylinder 2, at least in the second drying chamber 12.

[0135] According to Figures 1 to 6 the illustrated embodiment, the tubular protection member 19 in the second combustion chamber 13 protects the feed pipe 10 from the mixture of virgin material and RAP material that can move within the drying cylinder 2, as well as from the second flame 15 and the third flame 17.

[0136] The above-described material feeding system 5 is described in more detail below only with respect to the parts related to the second drying chamber 12 and the second combustion chamber 13 (i.e., the part for feeding the mixture of virgin material and RAP material).

[0137] The feeding system 5 includes a comb-shaped blade unit 21 fixed to the inner surface of the drying cylinder 2 at the second drying chamber 12.

[0138] The blade unit 21 causes the mixture to fall through the drying stream F15, corresponding to the heat exchange between the flue gas / material, due to which the temperature of the mixture increases before unloading.

[0139] In the presence of the second combustion chamber 13, the feeding system 5 includes a plurality of refractory plates 22 at the second combustion chamber 13 for protecting the base of the dryer 1.

[0140] The refractory plates 22 are configured to prevent the lifting of the material, so that the material slides forward on the bottom of the drying cylinder 2, for example, with reference to Figure 2 .

[0141] In this way, the mixture of the first material and the second material avoids the second flame 15 and / or the third flame 17, so that the recycled asphalt material does not release pollutant emissions due to the combustion of asphalt.

[0142] The present invention relates to a method for drying virgin inert stony materials and recycled bituminous materials.

[0143] The drying method is preferably carried out in a dryer of the dryer 1 type described above, with reference to dryer 1 below, without thereby limiting the scope of the present invention.

[0144] The method comprises introducing the virgin inert stony materials into dryer 1 and heating the virgin inert stony materials at least by means of a first drying gas stream F9 generated by a first flame 9.

[0145] The method comprises mixing the heated virgin inert stony materials with the recycled bituminous materials to obtain a mixture and heating the mixture with a second drying gas stream F15.

[0146] The first drying gas stream F9 and the second drying gas stream F15 impinge on the virgin inert stony materials.

[0147] The method comprises generating a second drying gas stream in a second drying chamber.

[0148] The second drying gas stream can be generated by a second flame 15 and a third flame 17 or by a hot air generator 26.

[0149] Advantageously, a second temperature of the second drying gas stream F15 is lower than a first temperature of the first drying gas stream F9.

[0150] The method comprises unloading the heated and dried mixture from the first drying gas stream F9 and the second drying gas stream F15 into dryer 1.

Claims

1. A dryer for an industrial plant for producing asphalt macadam, the dryer comprising: A drying cylinder (2) which rotates around its own main axis of extension (R2); a loading head (3) at the first end (2a) of the drying cylinder for introducing raw inert stone material into the drying cylinder; a discharge head (4) located at the second end (2b) of the drying cylinder; a feeding system (5) for feeding raw inert stone material from said loading head (3) to said unloading head (4) in a feeding direction (V); The drying cylinder (2) comprises a first drying chamber (6) and a first combustion chamber (7) located downstream of the first drying chamber (6) according to the feeding direction (V), The dryer comprises a first burner (8) located at the second end (2b) for generating a first flame (9) in the first combustion chamber (7) and a first drying flow (F9) in the first drying chamber (6); a feeding device (11) located downstream of the first combustion chamber (7) and upstream of the unloading head (4) in the feeding direction (V) for introducing recycled bituminous material into the drying drum (2), the feeding system (5) being configured for feeding a mixture of the original inert stone material and the recycled bituminous material downstream of the feeding device (11); The drying cylinder (2) comprises a second drying chamber (12) located downstream of the feed device (11) and upstream of the unloading head (4) in the feed direction (V), and the dryer comprises a system (25) for generating a drying gas flow, for generating a second drying gas flow (F15) at least in the second drying chamber (12).

2. The dryer according to claim 1, wherein: The system (25) for generating a drying gas flow comprises a second combustion chamber (13) in the drying cylinder (2), the second combustion chamber (13) being downstream of the second drying chamber (12) and upstream of the unloading head (4), the system (25) for generating a drying gas flow comprises at least one second burner (14, 16) having a power less than that of the first burner (8), for generating a second flame (15) in the second combustion chamber (13) and generating the second drying gas flow (F15) at least in the second drying chamber (12).

3. A dryer according to claim 2, comprising a third burner (16) for generating a third flame (17) in the second combustion chamber (13), the second burner (14) and the third burner (16) preferably having the same power, the second drying gas flow (F15) being determined by the second flame (15) and the third flame (17).

4. The dryer according to claim 3, wherein: The second burner (14) and / or the third burner (16) are located at the second end (2b) of the drying cylinder (2).

5. The dryer according to any one of claims 2 to 4, wherein: The ratio between the total length (L6+L7) of the first drying chamber (6) and the first combustion chamber (7) measured along the main extension axis (R2) and the total length (L12+L13) of the second drying chamber (12) and the second combustion chamber (13) measured along the main extension axis (R2) is between 1.5 and 2.

5.

6. The dryer according to any one of claims 2 to 5, wherein: The ratio between the length (L12) of the second drying chamber (12) measured along the main extension axis (R2) and the length (L13) of the second combustion chamber (13) measured along the main extension axis (R2) is between 1 and 4.

7. The dryer according to any one of claims 2 to 6, wherein: The power of the second burner (14) is between 0.5 MW and 4 MW.

8. A dryer according to any one of the preceding claims, wherein: The system (25) for generating a drying gas flow comprises a hot air generator (26) in communication with the second drying chamber (12) for feeding the second drying gas flow (F15) in the second drying chamber (12).

9. A dryer according to any one of the preceding claims, wherein: The first burner (8) comprises a feed duct (10) extending from the unloading head (4) to the first combustion chamber (7) in the drying cylinder (2), for feeding fuel to the first flame (9) in the first combustion chamber (7), the dryer comprising a tubular protector (19) for the feed duct (10), the feed duct (10) being inserted in the tubular protector (19).

10. The dryer according to claim 9, wherein: The tubular protective member (19) is fixed on the drying cylinder (2).

11. A dryer according to any one of the preceding claims, wherein: The feeding system (5) comprises a comb-shaped blade unit (21) supported on the inner surface of the drying cylinder (2) at the second drying chamber (12).

12. The dryer according to any one of claims 2 to 7, wherein: The feed system (5) comprises a blade unit (22) at the second combustion chamber (13) for maintaining the mixture supported by the inner surface of the drying cylinder (2).

13. A dryer according to any one of the preceding claims, wherein: The power of the first burner (8) is between 9 MW and 30 MW.

14. A method for drying raw inert stone material and recycled bituminous material, the method comprising: introducing the raw inert stone material into a dryer comprising a drying cylinder (2); heating the raw inert stone material with a first drying gas stream (F9) having a first temperature and generated by a first flame (9); mixing the heated original inert stone material with the recycled asphalt material to obtain a mixture; heating the mixture with a second drying gas stream (F15) having a second temperature lower than the first temperature; The mixture heated by the drying cylinder (2) is unloaded.

15. Drying method according to claim 14, comprising generating the second drying gas flow (F15) by means of at least a second flame (15, 17) in a second combustion chamber (13) in the drying cylinder (2).

16. The drying method according to claim 14, comprising generating the second drying gas flow (F15) by means of a hot air generator (26) and introducing the second drying gas flow (F15) into the drying cylinder (2).

17. The drying method according to any one of claims 14 to 16, wherein: The dryer is a dryer for an asphalt macadam industrial plant according to any one of claims 1 to 13.

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