WO2015067910A1

WO2015067910A1 - Device for the hot processing of granular products and method for regulating the temperature of emanations produced by a device for the hot processing of granular products

Info

Publication number: WO2015067910A1
Application number: PCT/FR2014/052862
Authority: WO
Inventors: Antoine Carrasco
Original assignee: Argumat
Priority date: 2013-11-08
Filing date: 2014-11-07
Publication date: 2015-05-14
Also published as: FR3013108A1; EP3066405A1; ES2859558T3; EP3066405B1; FR3013108B1

Abstract

The invention relates to a device (1) for processing granular products, comprising: - a chamber (2), - a heating means (5) designed to generate a drying flow (F) passing through a drying section (6B) of the chamber (2), - a main discharger (7A) of a main flow (P) of emanations, which is connected to said chamber (2), - a tapped-off discharger (7B) of a tapped-off flow (D) which is connected to said chamber (2) at the drying section (6B) and to said main discharger (7A) in order to transmit the tapped-off flow (D) to said main discharger (7A), and being characterized in that it comprises a system for regulating the temperature of the main flow (P) which system is designed to increase or decrease the flow rate of the tapped-off flow (D) as a function of the temperature of the main flow (P). Devices for processing granular products.

Description

HOT TREATMENT DEVICE FOR GRANULAR PRODUCTS AND METHOD FOR CONTROLLING THE TEMPERATURE OF EMANATIONS PRODUCED BY A HOT TREATMENT DEVICE OF GRANULAR PRODUCTS

TECHNICAL FIELD The present invention relates to the general technical field of heat treatment, including drying, granular products such as aggregates, pebbles or aggregates, which are intended for example for the manufacture of bituminous products. The present invention relates in particular to devices designed to perform such treatment, and to methods for controlling the temperature of volatile emissions produced by such heat treatment devices.

The present invention relates more particularly to a device for the hot treatment of granular products, such as pebbles or granulates, comprising:

an enclosure of substantially cylindrical general shape defining a longitudinal axis, the enclosure being provided, in the vicinity of one of its two ends, with a main entrance allowing the introduction of granular products into the interior of the enclosure; enclosure, and being provided, in the vicinity of the other end, with an outlet for extracting the granular products from said enclosure, said granular products being intended to undergo a treatment by circulating inside said enclosure since main entrance to the exit in a direction of traffic,

a heating means which is situated inside said enclosure, and which is designed to generate a drying flow directed against the current of the flow direction, and passing through a drying section of the enclosure, the flow of drying being able to contribute to the drying of said granular products within the drying section,

a main evacuator of volatile emanations produced inside the enclosure, the main evacuator being connected to said enclosure by a first branch, and being designed to evacuate out of the enclosure a main flow of emanations, a derivative evacuator which is connected on the one hand to said enclosure by a second branch at the drying section, upstream of the first branch in consideration of the drying flow to take a stream derived from fumes within said enclosure, the derivative evacuator being connected on the other hand to said main evacuator for transmitting the derived flow to said main evacuator, said derived evacuator being provided with a means for adjusting the flow rate of the derived flow.

The present invention also relates to a method for regulating the temperature of volatile fumes produced by a device for the hot treatment of granular products, such as pebbles or granulates, comprising:

an enclosure of substantially cylindrical general shape defining a longitudinal axis, the enclosure being provided, in the vicinity of one of its two ends, with a main entrance allowing the introduction of granular products inside the enclosure and being provided, in the vicinity of the other end, with an outlet allowing granular products to be extracted from said enclosure, said granular products being intended to undergo a treatment by circulating inside said enclosure since the main entrance to exit in one direction of traffic,

a main evacuator of volatile emanations produced inside the enclosure, the main evacuator being connected to said enclosure by a first branch and being designed to evacuate out of the enclosure a main flow of emanations,

said method comprising a step during which a flux derived from fumes produced inside said enclosure is taken at the drying section, upstream of the first branch in consideration of the drying flow, and in which the flow is transferred to said main evacuator.

PRIOR ART

The devices for the hot treatment of granular products, in particular aggregates intended for the manufacture of bituminous products of the asphalt type, are known and generally consist of rotary kilns generally qualified as drying drums, and optionally as coaters. The techniques used may be continuous or discontinuous techniques and operate according to a so-called "countercurrent" technique, when the displacement of the heating flow is in opposition relative to the displacement of the aggregates.

A known treatment device uses a drying oven in the form of a cylindrical body of revolution defining an enclosure having at least one inlet at one of its ends and an outlet at the other end, the furnace drying agent being rotated by any suitable means while the mass of aggregates or pebbles to be treated is introduced through the inlet so as to progress towards the outlet to be treated. The rotation of the enclosure thus makes it possible to circulate the aggregates that enter cold and wet through the inlet, towards the other outlet end, while stirring and raising them in the enclosure with the aid of all appropriate means. The known treatment device also uses a heating flux produced by a burner providing a flame in the enclosure. The flame produces a flow of hot air which propagates counter-current to the flow direction of the aggregates inside the enclosure, and which allows said aggregates to dry. Fumes are then generated in the heart of the enclosure, and formed in particular by dust from the aggregates, by the water vapor resulting from drying, and by gases generated by the combustion of the heating means. Fumes generally flow in the direction of the hot air flow.

It is therefore necessary to evacuate and treat these fumes, which are generally polluting. For this, it is known to provide the oven, at its inlet end, a smoke exhaust duct, opening for example on a bag filter for dusting said fumes before releasing them into the atmosphere.

When the temperature of the flue gases within the exhaust duct is below a dew point temperature, condensation may form which closes the bag filter, or causes progressive corrosion of the sheath. evacuation.

To overcome this problem, it is known to provide the furnace with a derivative channel connected on the one hand by means of heating, and on the other hand to the exhaust duct, so as to transmit heat generated by the heating means to said exhaust duct, and thus to heat the fumes within said exhaust duct.

The derived channel being designed to take heat at the heating means, it can be difficult to take, insofar as the heating means radiates (for example near the burner flame) to an intensity requiring the implementation of a derived channel specifically designed to resist radiation. In a corollary manner, the maximum heating power of the device is limited by such a design. In a harmful way, the derived channel, by taking heat, is also able to take a part of the oxidizer not burned by the burner, thus altering the quality of the combustion so as to generate polluting and / or toxic substances in the fumes. . On the other hand, of course, exhaust fumes should not be heated excessively, which would lead to a substantial waste of energy due to unnecessary generation of heat dispersed unnecessarily in the atmosphere, and other there is a risk of deterioration of the filter. For this purpose, the channel derived from the known device comprises a closure means designed to limit the heat transfer to the exhaust duct. In known manner, the opening of the closure means is controlled as a function of the flue gas temperature of the exhaust duct, in order to maintain said temperature in a tolerance range between the dew point temperature and a critical temperature Max. However, in the case where a relatively large quantity of aggregates has to be dried, it is necessary to provide an intense heating which may, on the contrary, lead to an undesirable rise in the flue gas temperature in the exhaust duct, for example of a nature to deteriorate the filter. Therefore, the amount of aggregates tractable by the device is limited to preserve the integrity of the devices located downstream of the exhaust duct, in the absence of means for cooling the fumes.

Furthermore, it may be advantageous to add a predetermined proportion of bituminous products from recycling (for example recovered during maintenance operations carried out on a roadway) to the new aggregates intended to be treated, in particular to lower the costs of maintenance. production of new bituminous products. It is then necessary to provide a more intense heating, such as to overheat the new aggregates so that they themselves communicate heat to products from recycling to dry. Also, the drying ability of recycled products is more variable than that of new aggregates because of their origin. Consequently, the temperature of the exhaust fumes is then likely to vary in a large amplitude depending on the nature of the products flowing in the enclosure, and can suddenly cause, undesirably, condensation, or on the contrary overheating in the evacuation duct. The objects assigned to the invention therefore aim to remedy the various disadvantages listed above and to propose a new treatment device and a new method for regulating the temperature of emanations of the treatment device in which regulation is particularly easy and free from all constraints, especially design. Another object of the invention is to propose a new treatment device and a new method for regulating the emitting temperature of the treatment device for effectively regulating the temperature of the emanations, even in the case where the drying abilities of the products to be treated are very variable. Another object of the invention is to propose a new treatment device and a new method for regulating the temperature of fumes of the treatment device whose energy efficiency is particularly high.

Another object of the invention is to propose a new treatment device and a new process for regulating the emitting temperature of the processing device of simple, robust and inexpensive design.

Another object of the invention is to propose a new treatment device and a new method for regulating the emitting temperature of the treatment device generating emanations whose temperature is within a range that makes it possible to avoid deterioration of the equipment. located downstream of the production.

Another object of the invention is to propose a novel treatment device and a new process for regulating the temperature of emanations of the treatment device making it possible to treat granular products with eclectic, new or recycled properties.

SUMMARY OF THE INVENTION

The objects assigned to the invention are achieved by means of a device for the hot treatment of granular products, such as pebbles or granulates, comprising:

an enclosure of substantially cylindrical general shape defining a longitudinal axis, the enclosure being provided, in the vicinity of one of its two ends, with a main entrance allowing the introduction of granular products inside the enclosure; and being provided, in the vicinity of the other end, with an outlet allowing granular products to be extracted from said enclosure, said granular products being intended to undergo a treatment by circulating inside said enclosure since the main entrance to exit in one direction of traffic,

a heating means which is situated inside said enclosure, and which is designed to generate a drying flow directed against the current of the flow direction, and passing through a drying section of the enclosure, the flow of drying being fit to contribute to the drying of said granular products within the drying section,

a main evacuator of volatile emanations produced inside the enclosure, the main evacuator being connected to said enclosure by a first branch, and being designed to evacuate out of the enclosure a main flow of emanations,

a derivative evacuator which is connected on the one hand to said enclosure by a second branch at the drying section, upstream of the first branch in consideration of the drying flow to take a stream derived from fumes within said enclosure, the derived evacuator being connected on the other hand to said main evacuator for transmitting the derived flow to said main evacuator, said derived evacuator being provided with a means for adjusting the flow of the derived flow,

the treatment device being characterized in that it comprises a main flow temperature control system adapted to act on the control means to increase or decrease the flow rate of the derived flow as a function of the temperature of the main flow. .

The objects assigned to the invention are also achieved by means of a process for regulating the temperature of volatile fumes produced by a device for the hot treatment of granular products, such as pebbles or granulates, comprising:

said method comprising a step during which a flux derived from fumes produced inside said enclosure at the level of the drying section is taken upstream of the first branch in consideration of the drying flow, and in the course of which the derived flow is transmitted to said main evacuator, the method being characterized in that it comprises a step during which the flow rate of the derived flow transmitted to the main evacuator is increased or reduced as a function of the temperature of the main flow. .

SUMMARY DESCRIPTION OF THE DRAWINGS Other particularities and advantages of the invention will appear and will appear in more detail on reading the description given below, with reference to the accompanying drawings, given solely by way of illustrative and nonlimiting example, in which :

- Figure 1 illustrates, in a schematic longitudinal sectional view, a general view of a granular products processing device according to the invention. - Figure 2 shows, in a perspective view locally in section, a drying section and a combustion section of the device of Figure 1.

FIG. 3 represents, in a perspective view in sectional view, the drying section, the combustion section and a kneading section of the device of FIG. 1. FIG. 4 represents, in a perspective view in longitudinal section. , the drying section, the combustion section and a main inlet of the device of FIG. - Figure 5 shows, in a schematic longitudinal sectional view, a detail of the device of Figure 1, namely a device for sampling the device of Figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 illustrates a general view of a device 1 for treating granular products, such as pebbles or granulates, according to the invention.

Within the meaning of the invention, the "granular products" to be treated are in the form of a plurality of mineral solid elements such as pebbles, chippings, or aggregates, which may be of variable size and shape, and which are preferably intended to be part of asphalt-type bituminous products after, for example, a coating operation with bitumen. Thus, the granular products are preferably intended for use in the field of public works.

The treatment device 1 according to the invention is designed to communicate one or more transformation (s), for example of a physico-chemical type, to the granular products introduced therein, the treatment including heating allowing the partial or complete drying of said products. granular. Of course, the treatment may include additional operations, for example asphalt coating granular products, or addition of additives to said granular products. According to the invention, and as illustrated in FIGS. 1 to 4, the device 1 for treating granular products with heat comprises an enclosure 2 of substantially cylindrical general shape defining a longitudinal axis X-X '. The enclosure 2 is thus in the form of a hollow revolution solid forming a drum, the axis of revolution of which is formed by longitudinal axis X-X ', said enclosure 2 comprising an outer envelope formed in particular by a wall lateral 18 extending from one end to the other of the cylinder, enclosing an interior space in which the granular products are intended to be treated. The enclosure 2 is, because of its shape of revolution, particularly adapted to be rotated about the longitudinal axis X-X '. Of course, the chamber 2 according to the invention may be formed by a succession of cylindrical shapes of different diameters, or by another form of revolution without departing from the scope of the invention.

According to the invention, the enclosure 2 is provided, in the vicinity of one of its two ends, with a main entrance 3A allowing the introduction of granular products inside the enclosure 2, and being provided, in the vicinity of the other end, an outlet 4 for extracting the granular products from said enclosure 2, said granular products being intended to be treated by circulating inside said chamber 2 from the main entrance 3A to exit 4 in a direction of circulation C. The granular products are intended to be inserted in the chamber 2 through the main entrance 3A while they are preferably cold and / or wet, for example to using a conveyor 18 (as shown in Figure 1). The main entrance 3A is thus designed to admit most of the raw materials to be transformed into the enclosure. The outlet 4, located substantially opposite the chamber 2 vis-à-vis the entrance, allows the evacuation or extraction of finished products or not, and in particular granular products treated in the heart of said enclosure 2, towards the outside of said enclosure 2 (the products leaving the enclosure 2 through the outlet 4 can for example fall by gravity into a recovery hopper not shown). The granular products discharged through outlet 4 are treated products, preferably heated and / or dried granular products, and / or coated, and / or mixed with additives and / or mixed with products derived from the recycling of bituminous products ( for example, recovered during maintenance operations carried out on a roadway). The granular products discharged through the outlet 4 are likely to undergo subsequent treatments within devices arranged downstream of the treatment device 1 in order to form finished products. Preferably, the granular products circulate from one end to the other of the enclosure 2, from the main inlet 3A to the outlet 4, without leaving the interior of the enclosure 2 during the treatment. Thus, the treatment of the granular products is preferably carried out continuously inside the chamber 2. The design of the device 1 is thus relatively simple, and particularly fast processing. Preferably, the chamber 2 is rotated by a conventional drive means (not shown) and its longitudinal axis XX 'is inclined so that the main entrance 3A is placed at an altitude greater than the exit 4 , for promote the progression by gravity granular products in the direction of flow C. The wall 18 of the chamber 2 may be provided, near the main inlet 3A, 19A admission vanes forming for example a propeller axis the longitudinal axis X-X ', and to facilitate the introduction of granular products in the chamber 2, or to induce the direction of circulation C to them. Similarly, the wall 18 of the enclosure 2 may be provided with extraction vanes 19B designed to direct the treated products towards the outlet 4 (which is for example located in a low area of the enclosure 2) , and avoid in particular the agglutination of the latter at the end of said enclosure 2. Of the treatments that are subjected to undergo the granular products during their passage within the chamber 2, said granular products are intended to undergo a heating of nature to dry them. For this, the processing device 1 according to the invention comprises a heating means 5 which is located inside said enclosure 2. The heating means 5 according to the invention can be in the form of any known means allowing heating granular products, heating resistance type, heating by electromagnetic induction or by microwave, but is preferably in the form of a fuel burner, for example fuel oil or gas (as illustrated in FIG. 1), emitting a radiating flame and / or of a nature to generate heat by conduction and by convection. Preferably, the flame generated in the heart of the chamber 2 contributes to defining a combustion section 6C of said chamber 2 at which said flame is located. Preferably, the side wall 18 of the chamber 2 is protected from the heating means at the combustion section 6C by suitable protection plates 20. Within the combustion section 6C, the granular products may optionally be circulated between the protective plates 20 and the side wall 18 to be protected from the heating means 5.

As shown in FIG. 1, the heating means 5 formed by the burner is designed to generate heat in an oriented manner, for example creating a stream of air or hot gas channeled through the side wall 18 of said enclosure 2. According to the invention, the heating means 5 is designed to generate a drying flow F oriented countercurrent to the flow direction C, and passing through a drying section 6B of the enclosure 2, the drying flow F being able to (at least) contribute to, if not insure totally drying said granular products within the drying section 6B. The treatment device 1 according to the invention thus has a so-called "countercurrent" operation, the drying flow F being oriented in opposition to the flow direction C of the granular products in order to force all or part of the moisture of said products. granular to vaporize under the effect of dry heat, and to cause this moisture in gaseous form with said drying flow F, to contribute to form a main flow P of volatile fumes (described in more detail below) . The drying flow F is thus oriented from the outlet 4 to the main inlet 3A, and is preferably emitted from the vicinity of the outlet end 4 of the enclosure 2, or in a middle portion of the enclosure located between exit 4 and main entrance 3A, depending on the different treatments to be applied to the granular products.

The drying flow F according to the invention passes through the drying section 6B, in which it is particularly suitable for drying the granular products, for example by being neither too hot nor too cold. The drying section 6B is the main seat for drying the granular products in the heart of the chamber, especially since the radiation produced by the heating means 5 is preferably less intense than in the combustion section 6C, so that granular products are less likely to be burned by radiation or by the flame itself. Preferably, the chamber 2 comprises successively the drying section 6B, the combustion section 6C, and a mixing section 6A (as shown in Figures 1 to 4) in consideration of the direction of circulation C, the mixing section 6A being arranged downstream of the heating means 5 and making it possible to mix and mix the granular products before they exit the enclosure 2 via the outlet 4. The mixing section 6A is preferably provided for mixing and stirring the granular products (new and / or recycled) with bitumen, to form coated products such as asphalt. The kneading section 6A may also be provided, preferably, for mixing the new granular products with granular products resulting from recycling, which have for example been introduced into said chamber 2 by an auxiliary inlet 3B (which is described below). ) of said enclosure 2. Preferably, the chamber 2 is provided at the level of the drying section 6B lifting means 16 granular products circulating in said chamber 2, the lifting means 16 being designed to lift and release said granular products during their circulating in said enclosure 2 to form a curtain of granular products through which the drying flow F is intended to pass. The lifting means 16 thus make it possible, thanks to the rotation of the enclosure 2, to create a mist of granular products covering all or part of the internal cross-section of said enclosure 2, the granular products twirling from top to bottom (or in any directions) of the side wall 18 to be aerated and dried individually, such a movement of the granular products promoting in particular the chemical and thermal exchanges between the drying flow F and said granular products to allow optimal drying of said granular products by heat absorption of said drying flow F.

In addition, and particularly advantageously, the lifting means 16 of the drying section 6B preferably form a means of cooling the drying flow F, which reaches the end of the chamber 2 near the main entrance 3A with a temperature below the temperature of said drying flow F before it has passed said drying section 6B.

Preferably, said enclosure 2 is rotatable about its longitudinal axis X-X ', the raising means 16 comprising at least two rows 11 of adjoining lifting buckets, said buckets being distributed for each row 11 over at least the majority of the circumference of said enclosure 2, and being designed to lift the granular products circulating in said enclosure 2 during the rotation thereof, to form at least one curtain of granular products covering all or part of the inner cross section of the enclosure 2.

The buckets form shovels (or trays) oriented so, during the rotation of the chamber 2, fill with granular products (when the rotation brings the buckets in the lower zone of the processing device 1), and then lift said granular products (when the rotation raises the buckets to an altitude close to the longitudinal axis X-X '), and finally pouring said granular products (when the rotation brings the buckets high zone of the treatment device 1, the buckets then being reversed). Preferably, buckets are double volume lifting buckets, comprising two nested trays (in particular illustrated in Figure 4) allowing the formation of a curtain of dense granular products. Each row 11 of bucket is formed of an annular arrangement of a plurality of buckets attached to the side wall 18. Preferably, the enclosure 2 comprises at least one annular dam 12 (as illustrated in Figures 1 and 4 ) of separation of the rows of buckets 11 interposed between two rows 11 contigDes buckets, said at least one annular dam 12 being designed to limit the flow of granular products from a row 11 of buckets to the other. Said at least one annular dam 12 is preferably formed by an annular flat wall perpendicular to the longitudinal axis X-X ', and disposed concentrically with the enclosure 2 inside the latter, said at least one dike annular 12 being attached to the side wall 18 by a first edge, the second edge rising towards the longitudinal axis XX 'at a height substantially equal to that of the buckets protruding from said side wall 18 (as illustrated in FIG. Figure 4). The annular dam 12 interposes the passage of granular products from one row 11 to the other, forcing them to approach the axis XX 'to be able to circulate in the direction of circulation C. Thanks to such provision, the granular products are retained in the drying section 6B for a long time, regardless of the flow rate of said granular products, and in particular when the flow rate of said granular products is low.

Of course, the drying section 6B may include lifting devices 16 different from those mentioned without departing from the scope of the invention, since they allow to form a curtain of granular products capable of cooling the drying flow F. Furthermore, according to the invention, the device 1 for treating granular products with heat comprises a main evacuator 7 A of volatile emanations produced inside the enclosure 2, the main evacuator 7A being connected to said enclosure 2 by a first branch 8A, and being designed to evacuate from the enclosure 2 a main flow P emanations. The treatment of the granular products in the chamber 2 is capable of generating at the heart thereof volatile emanations which are entrained by the drying flow F. These volatile emanations are in the form of a fluid with gaseous behavior emerging. the processing of granular products, in particular their drying, and carrying with it particles (for example dust granular products) and / or water in gaseous form from drying. The products of the combustion of the heating means (such as, for example, carbon compounds of the carbon dioxide or carbon monoxide type, or "NOx" type nitrogen oxides) also contribute to forming the volatile emanations. The volatile fumes are in the form of charged fumes comprising both water in the form of steam, products of the combustion of the heating means 5, and suspended dust from the drying of the granular products. Other components related to other treatments carried out in the chamber 2 may also contribute to forming the volatile emanations. Of course, these volatile emanations are likely to be polluting, and / or to stifle the combustion in a way that is detrimental to the operation of the heating means 5 (which requires, for example, a fresh oxidant input of the oxygen type to function) and requires be evacuated, and / or cleaned up.

Thus, the main evacuator 7A is designed to receive, evacuate, and possibly depollute all or part of the emanations carried by the drying flow F. For this, the main evacuator preferably has the form of a discharge duct, connected at its side directly to the chamber 2 by an access opening forming the first branch 8A (as shown in Figure 1). The first branch 8A, within the meaning of the invention forms a link between the interior space of the chamber 2 and the interior of the main evacuator 7A, in order to communicate (in a controlled manner or not, and / or filtered or not) these two interior spaces to allow the circulation of fumes from one to the other of said interior spaces. Preferably, the first branch 8A is designed such that the granular products can not substantially penetrate into the main evacuator 7A (the passage being prohibited granular products for example using a grid or a path in chicane) the inlet vanes 19A can for example also contribute to such a technical effect. Thus, the main evacuator 7A is designed to admit substantially only the volatile fumes forming the main flow P (preferably carrying dust in suspension), and not to admit granular products within it.

Preferably, the first branch 8A is connected to said enclosure 2 at or upstream of the main entrance 3A in consideration of the direction of circulation C of the granular products, for example at the end of the enclosure 2, so that the drying flow F is able to drain the volatile emissions over the entire length of the chamber 2 to escape through the first branch 8A by the main evacuator 7A. Preferably, the first branch 8A is connected downstream of the drying section 6B in consideration of the drying fiow F. In this respect, FIG. 1 represents a treatment device 1 according to the invention of which the main evacuator 7A is connected. via the first branch 8A at the end of the enclosure, parallel to the main entrance 3A. Of course, the main evacuator 7A may be connected to the chamber 2 at a different location, since it allows to evacuate the main flow P of fumes outside the chamber 2.

As soon as the drying flow F, carrying the emanations, leaves the enclosure 2 by crossing the first branch 8A, it becomes, in the sense of the invention, the main flow P of fumes, no longer used for drying, but being simply intended to be evacuated, and / or depolluted. In order to depollute the main flow P, the main evacuator 7A preferably comprises a filtering device, for example of the baghouse type, through which the main flow P is intended to be filtered in order to be freed from all or part of its particles. polluting. Other depolluting treatments may be implemented within the main evacuator 7A or downstream thereof, before for example rejection of the main flow P in the atmosphere, or storage of filtered emanations.

The treatment device 1 according to the invention also comprises a derivative evacuator 7B which is connected on the one hand to said enclosure 2 by a second branch 8B upstream of the first branch 8A in consideration of the drying flow F, to take a derived stream D of fumes inside said enclosure 2, the derivative evacuator 7B being connected on the other hand to said main evacuator 7A for transmitting the derivative flow D to said main evacuator 7A.

The first branch 8A is distinct from the second branch 8B. The derivative evacuator 7B is thus designed to divert a part of the emanations flowing inside the chamber 2 from a different location of the chamber 2 from the one where the first branch 8A is located (preferably one a place where the fumes are warmer than the fumes passing through the first branch 8A), preferably from the side wall 18 at which the second branch 8B connects said branched outflow 7B. The derivative evacuator 7B thus subtracts a certain amount of the emanations carried by the drying flow F in order to form within the said derivative evacuator 7B the derived flow D of emanations. Advantageously, the temperature of the emanations of the derived stream D taken upstream of the first branch 8A in consideration of the drying flow F are at a temperature different from those taken at the first branch 8A. Preferably, all the emanations are extracted from the interior of the chamber 2 by the action, or the mere presence, joint of the main evacuator 7A and the evacuator derivative 7B.

The derivative evacuator 7B is connected to the main evacuator 7A, for example at a third branch 8C (as shown in FIG. 1), which allows the derivative stream D to flow from inside the enclosure 2 at the second branch to the interior of (main evacuator 7A, in which the emanations of said derived stream D are brought into contact and / or mixed with those of the main stream P. Alternatively, the derived stream D d ' and the main flow P may simply be subjected to a heat exchange to exchange their heat without contact, for example within a heat exchanger (not shown) of the main evacuator 7A.

Preferably, said derivative evacuator 7B comprises a duct 9 connected on the one hand to said enclosure 2 by the second branch 8B and on the other hand to said main evacuator 7A in order to connect said enclosure 2 to said main evacuator 7A (as shown in FIG. Figure 1). Preferably, the pipe extends from the first branch 8B, placed in the upper part of the enclosure 2, and forms a bend.

In the manner of the first branch 8A, the second branch 8B forms a link between the interior space of the chamber 2 and the interior space of the derived revolving member 7B, in order to communicate (in a controlled or non-controlled manner, and / or filtered or not) these two interior spaces to allow the circulation of the emanations from one to the other of said interior spaces. Preferably, the second branch 8B is designed in such a way that the granular products can not substantially penetrate into the branched evacuator 7B (the passage being prohibited to granular products, for example using a grid or a baffled path ) a device for sampling the derived stream D preferably contributing to produce such a technical effect. Thus, main evacuator 7A is designed to admit substantially only the volatile emanations forming the derivative stream D (preferably containing suspended dusts), and not to admit granular products within it. Preferably, the processing device 1 comprises a device for sampling the derived stream D (as schematically illustrated in FIG. 5, and represented in FIGS. 2 to 4), comprising:

at least one sampling aperture 13 of the derivative stream D formed at the periphery of said enclosure 2, through the side wall 18, at the level of the second branch 8B, the sampling aperture 13 forming, for example, a sufficiently tortuous path for the fumes can rush through it while substantially preventing the intrusion of granular products,

an annular skirt 14 extending between an inner edge 14A and a free portion 14B, the annular skirt 14 being attached by the inner edge 14A inside said enclosure 2 upstream of said at least one sampling aperture 13 in considering the direction of circulation C granular products, the free portion 14B covering at least the majority of said at least one sampling opening 13, so as to form a screen or shield drifting the granular products away from said at least one sampling opening, while at the same time encouraging the emanations (carried by the flow of Drying F) to rush under said annular skirt 14 in order to penetrate the sampling openings 3,

- At least one dam blade 15 attached to the inside of said chamber 2, arranged helically relative to the longitudinal axis XX \ and disposed downstream of said at least one sampling opening 13 in consideration of the direction of flow C granular products, the arrangement and the shape of said at least one dam blade 15 for repelling granular products that would be able to circulate incidentally in the opposite direction of the flow direction C, the arrangement and the shape of said at least one blade dam 15 however allowing the passage of fumes under the annular skirt 14.

The shape and the disposition of the annular skirt 14 make it possible, by taking advantage of the flow direction C of the granular products opposed to the drying flow F carrying the fumes, to create an annular opening oriented in a manner favorable to the penetration of a portion of the emanations under said annular skirt 14 while this annular opening remains inaccessible to any granular product circulating in the direction of flow C. The annular skirt 14 thus houses said at least one sampling opening 13 granular products.

Preferably, and as shown in the figures, the annular skirt 14 is provided on its free portion with a row 11 of lifting blades. Preferably, the sampling device comprises a plurality of barrier vanes 15 and a plurality of sampling openings 13 connected to an annular collector 21 (shown schematically in FIG. 1), non-rotating, encircling the enclosure 2 and conducting the emitted fumes. by the different sampling apertures 13 at the second branch 8B and then at the branched evacuator 7B. Preferably, the lifting means 16 are designed to form a curtain of granular products at the drying section 6B, the curtain of granular products being able to absorb a quantity of heat drying flow F sufficient for the temperature of the main flow P is kept below a critical temperature. The critical temperature can be defined for example by the temperature above which the main spillway 3A is deteriorated, or its impaired operation. Thus, the drying section 6B provided with the lifting means 16 forms a means of cooling the main stream P of fumes, while the derived stream D forms a means for heating the main stream P of fumes.

According to an important characteristic of the invention, the derivative evacuator 7B is connected to the enclosure 2 by the second branch 8B at the drying section 6B. Thus the derivative evacuator 7B can take a derivative stream D of emanations formed by emanations from the drying section 6B of said enclosure 2.

Thus, advantageously, the fumes forming the derived stream D taken from the drying section are hotter than those taken by the main spillway 7A to form the main flow P downstream of the second branch 8B, in consideration of the drying flow. F. The fumes forming the derivative stream D thus serve as heat transfer fluid to be mixed with the main flow P to heat the latter.

Thus, the derived evacuator 7B is connected to said enclosure 2 by the second branch 8B away from the combustion section 6B, within which the radiation and / or the heat produced by the heating means 5 would be capable of altering or damaging the second branch 8B and / or the branched outfall 7B. In addition, the derivative evacuator 7B is connected to said enclosure 2 by the second branch 8B away from the combustion section 6B to substantially avoid discharging, with the fumes, a certain proportion of unconsumed oxidant necessary for operation heating means 5, the oxidizer being formed for example by fresh air containing oxygen, admitted in the heating means 5 upstream of said heating means 5 in consideration of the drying flow F, the oxidant content of the the internal air of said chamber 2 at the drying section 6B being much lower than the oxidant content of the interior air of said chamber 2 at the combustion section 6C and kneading 6A.

The branched evacuator 7B connected to the chamber 2 at the drying section 6B thus makes it possible to collect a relatively large quantity of emanations, which are relatively dense, relative to, for example, the quantity of unpolluted air or of oxidant incidentally removed. Advantageously, a small amount of air polluted will be wasted by evacuation in the main evacuator 7A, which allows the derivative stream D to constitute in addition a high-performance coolant.

Preferably, the processing device 1 comprises an auxiliary input 3B of granular products distinct from the main entrance 3A and connected to said enclosure 2 between the main entrance 3A and the outlet 4, as represented in FIGS. 1 to 4. The auxiliary input 3B is preferably provided with a hopper 22 located on the top of the enclosure 2 and allowing the insertion of granular products in the heart of said enclosure 2. At the auxiliary input 3B, auxiliary blades intake 23 disposed within the enclosure 2 helically on the side wall 18 in consideration of the longitudinal axis XX 'preferably allows a setting in motion in the direction of circulation C substantially immediately granular products introduced by the auxiliary inlet 3B, said granular products thus introduced mixing with the granular products already present in the chamber 2 and having crossed for example the drying section 6B. The auxiliary inlet 3B advantageously allows the introduction of granular products of a different nature from those introduced by the main inlet 3A, and intended to undergo a different treatment (for example not including a passage at the drying section 6B) in the heart of the enclosure 2.

Preferably, the auxiliary input 3B is connected to said enclosure 2 between the second branch 8B and the heating means 5. Such an arrangement ensures that the derivative stream D remains hot, not being cooled by the granular products ( usually cold and wet) introduced by the auxiliary input 3B.

Preferably, the auxiliary inlet 3B is designed and adapted to allow the introduction of granular products derived from the recycling of bituminous product (and / or addition elements for the treatment), which are of size and / or composition and or more variable particle size than in the case of new granular products (of the type that can be introduced for example by the main entrance 3A), and are likely to include a variable proportion of foreign elements such as bitumen or other undesirable elements. Granular products from recycling for example, are recovered during maintenance operations carried out on a roadway.

Advantageously, the granular products introduced into the chamber 2 via the auxiliary inlet 3B circulate in the chamber 2 from said auxiliary inlet 3B to the outlet 4, in the direction of circulation C, preferably without The processing of the granular products introduced by the auxiliary inlet 3B is thus advantageously carried out continuously inside the enclosure 2.

Preferably, the derivative evacuator 7B is provided with means 10 for regulating the flow rate of the derivative stream D, formed for example by a valve 10 (as shown in FIG. 1) designed to move between an open or closed position. in order to seal or not said derivative evacuator 7B, and in particular to close or not the duct 9 of said derivative evacuator 7B, with the aim of interrupting, hindering or selectively authorizing the passage of the emanations of said derivative stream D. valve 10 may be placed for example at the third branch 8C, as shown in FIGS. The adjusting means 10 may also comprise a second valve (not shown), preferably placed within the branched evacuator 7B, for example at the second branch 8B, in order to better control the flow rate of the derivative stream D. Of course any other means making it possible to authorize, prohibit, or regulate the flow rate of the admission of the derived stream D into the derivative evacuator 7B may be implemented without departing from the scope of the invention, such that a valve, or a butterfly valve, or a combination of these elements, placed at the first, second, and / or third branch 8A, 8B, 8C, and / or within the main spinner 7A and / or derivative 7B, so as to control the flow rate of the main flow P and / or the flow derivative D.

Preferably, the processing device 1 comprises a system for regulating the temperature of the main flow P designed to act on the adjustment means 10 in order to increase or reduce the flow rate of the derived flow D as a function of the temperature of the main flow. P. The admission of a more or less significant flow of D-derivative flow in the main evacuator 7A makes it possible, by mixing said derived flow D with the main flow P within said main evacuator 7A, to vary the temperature of the flux main 7A, said main stream 7A and derivative 7B being of different temperatures, the derivative stream 7B being preferentially hotter than the main stream 7A. The temperature control system may comprise one or more temperature sensors of the main flow P and the derived flow D, and a control device of the adjustment means 10 as a function of the temperatures sensed.

Preferably, the control system is designed to increase the flow rate of the derivative flow D when the temperature of said main flow P is lower than a set temperature, and to reduce the flow rate of the derivative flow D when the temperature of said main flow P is greater than the set temperature. Preferably, the heating means formed by the derivative stream D is thus adjustable, while the cooling means formed by the drying section 6B provided with raising means 6B to form the curtain of granular products is permanently active. Activation of the derivative stream D may thus allow, for example, the main stream P to be heated to be maintained at a temperature greater than the dew point temperature, thus avoiding the formation of condensation in the main evacuator 7A, and possibly downstream of the latter. On the contrary, the weakening of the derivative flow rate D makes it possible for the main stream P to cool itself by means of the cooling means, which may for example make it possible to avoid the deterioration of pollution control installations located downstream of the reactor. main evacuator 7A. In particular, the main flow P is liable to undergo large temperature variations during the introduction, for example of granular products from the recycling of bituminous products, since their receptivity to drying by their drying flow F is likely to to be very variable. In addition, to treat both granular products introduced by the main inlet 3A and the auxiliary inlet 3B, it may be necessary to increase the amount of heat produced by the heating means 5, which may have As a consequence of varying the temperature of the main flow P. In any situation, and whatever the quantity or the quality of the granular products admitted into the enclosure 2, by any entry (3A, 3B) thereof, the temperature of the main flow P is thus kept constant, or slightly variable, within a tolerance interval, in which the main flow P is sufficiently hot for example, not to generate condensation, and is cold enough not to damage or alter the main spinner 7A.

Thus it is possible to maintain the temperature of the main flow P in this range, which is preferably between 50 ° C and 170 ° C, even more preferably between 70 ° C and 150 ° C, more preferably between 80 ° C and 130 ° C.

The invention also relates to a method for regulating the temperature of volatile fumes produced by a device 1 for treating granular products such as pebbles or granulates, comprising:

an enclosure 2 of substantially cylindrical general shape defining a longitudinal axis X-X ', the enclosure 2 being provided, in the vicinity of one of its two ends, with a main inlet 3A allowing the introduction of granular products to the inside of the chamber 2, and being provided, in the vicinity of the other end, with an outlet 4 allowing the granular products to be extracted from said enclosure 2, said granular products being intended to be treated while circulating inside said enclosure 2 from the main entrance 3A to the outlet 4 in a direction of circulation C,

a heating means 5 which is located inside said enclosure 2, and which is designed to generate a drying flow F oriented counter-current to the flow direction C, and passing through a drying section 6B of the enclosure 2, the drying flow F being able to contribute to the drying of said granular products within the drying section 6B,

a main evacuator 7A of volatile fumes produced inside the enclosure 2, the main evacuator 7A being connected to said enclosure 2 by a first branch 8A, and being designed to evacuate out of the enclosure 2 a flow main P of fumes.

said method comprising a step during which a derivative stream D of emanations produced inside said enclosure 2 upstream of the first branch 8A is taken in consideration of the drying flow F, and during which the flow is transmitted. D derivative to said main evacuator 7A, and being characterized in that the derivative stream D is taken at the drying section 6B. The derived stream D is taken at a level distinct from the main stream P, so that said derived streams D and main P have a different temperature.

Thus, to contribute to the regulation of the temperature of the main flow P of emanations within the main evacuator, we subtract a portion of the emanations circulating in the chamber 2 (carried preferably by the drying flow F) at of the drying section 6B, to form the derivative stream D of fumes, to then bring into contact and / or mix the derivative stream D with the main stream P. Instead of mixing the main stream P and derivative D, one may consider, without departing from the scope of the invention, to subject them to a simple heat exchange, without necessarily being in contact, for example within a heat exchanger (not shown) of the main evacuator 7A . The main flows P and derivative D are advantageously at a temperature different from each other, insofar as they are taken at a different location from the chamber 2.

Preferably, the method of controlling the temperature of volatile fumes is implemented using the processing device 1 described above and illustrated in FIGS. Therefore, the derivation is preferably carried out using a derivative evacuator 7B as described above.

Preferably, the regulation method comprises a step during which the flow rate of the derived flow D transmitted to the main evacuator 7 A is increased or reduced as a function of the temperature of the main flow P, the contribution of the derived flow D to main flow P for varying the temperature of said main flow P when it absorbs said flow derivative, or at least absorbs heat, within the main evacuator 7A. By controlling the flow rate of the derivative stream D, it is thus possible to control the temperature of the main flow. Preferably, the flow rate of the derived flow D transmitted to the main evacuator 7A is increased when the temperature of said main flow P is lower than a set temperature, and the flow rate of the derived flow D transmitted to the main evacuator 7A is reduced when the temperature of said main flow P is greater than the set temperature. The derivative stream D containing emanations whose temperature is advantageously greater than that of the emanations of the stream main P, it is thus possible to use the derivative flow D to heat up the main flow P. The reduction of, or the absence of, flow rate derivative D transmitted to the main evacuator 7A allows the main flow P not to be heated , so that he is able to cool down. In fact, when it is not heated with the aid of the derivative stream D, the emanations of the main stream P are relatively cold, since the drying flow F intended to form said main stream P on arrival in the main evacuator P is preferably passed through the drying section 6B, provided with means for cooling said drying flow F, such as lifting means 16, the cooling means being such as to sufficiently cool said drying flow F so that said main flow P never reaches a critical temperature (regardless of the nature or quantity of the granular products introduced into the enclosure 2), such as, for example, to damage or alter the main spillway 3A or any equipment downstream of the latter. Preferably, the control method comprises a step during which granular products from the recycling of bituminous products are introduced into said chamber 2 between the main inlet 3A and the outlet 4, preferably an auxiliary inlet 3B. Thanks to the design of the treatment device 1 described above, it is advantageous to introduce granular products whose thermal receptivity is highly variable, without risk of excessive changes in the temperature of the main flow P emanations.

Preferably, the granular products from the recycling of bituminous products in the chamber 2 are introduced between the level at which the D-flow is taken and the said heating means 5. Introduce the granular products from the recycling of bituminous products into the enclosure 2 at such a level ensures that the derivative stream D remains hot, not being cooled by said granular products (generally cold and wet) introduced by the auxiliary input 3B.

Of course, it is also possible to introduce other elements, jointly or alternatively to granular products from recycling, such as additives for the treatment (for example a coating product such as bitumen) through the auxiliary inlet 3B, or elsewhere in the enclosure 2.

POSSIBILITY OF INDUSTRIAL APPLICATION

The invention finds its industrial application in the design, production, and implementation of hot treatments of granular products such as pebbles or aggregates.

Claims

Device for treating (1) hot granular products, such as pebbles or aggregates, comprising:

an enclosure (2) of substantially cylindrical general shape defining a longitudinal axis (Χ-Χ '), the enclosure (2) being provided, in the vicinity of one of its two ends, with a main inlet (3A) allowing the introduction of granular products inside the enclosure (2), and being provided, in the vicinity of the other end, with an outlet (4) for extracting the granular products from said enclosure ( 2), said granular products being intended to be treated by circulating inside said enclosure (2) from the main inlet (3A) to the outlet (4) in a direction of circulation (C),

- heating means (5) which is located inside said enclosure (2), and which is designed to generate a drying flow (F) oriented against the flow direction (C), and through a drying section (6B) of the enclosure (2), the drying flow (F) being able to contribute to the drying of said granular products within the drying section (6B),

a main evacuator (7A) of volatile fumes produced inside the enclosure (2), the main evacuator (7A) being connected to said enclosure (2) by a first branch (8A), and being designed to evacuate from the enclosure (2) a main flow (P) of fumes,

a derivative evacuator (7B) which is connected on the one hand to said enclosure (2) by a second branch (8B) at the drying section (6B), upstream of the first branch (8A) in consideration of the flow drying device (F) for sampling a derivative flow (D) of fumes inside said enclosure (2), the derivative evacuator (7B) being connected on the other hand to said main evacuator (7A) for transmitting the flow derivative (D) to said main evacuator (7A), said derivative evacuator (7B) being provided with means (10) for adjusting the flow rate of the derivative stream (D), the treatment device (1) being characterized in that it comprises a system for regulating the temperature of the main flow (P) designed to act on the means of setting (10) to increase or decrease the flow of the derivative stream (D) as a function of the main flow temperature (P).

Treatment device (1) according to claim 1, characterized in that it comprises an auxiliary input (3B) of granular products distinct from the main entrance (3A) and connected to said enclosure (2) between the main entrance ( 3A) and the output (4).

Treatment device (1) according to claim 2, characterized in that the auxiliary input (3B) is connected to said enclosure (2) between said second branch (8B) and said heating means (5).

Treatment device (1) according to any one of the preceding claims, characterized in that said derivative evacuator (7B) comprises a duct (9) connected on the one hand to said enclosure (2) by the second branch (8B) and on the other hand to said main evacuator (7A) for connecting said enclosure (2) to said main evacuator (7A).

Treatment device (1) according to the preceding claim, characterized in that the control system is designed to increase the flow rate of the derivative flow (D) when the temperature of said main flow (P) is lower than a set temperature, and for reducing the flow rate of the derivative flow (D) when the temperature of said main flow (P) is higher than the set temperature.

Treatment device (1) according to any one of the preceding claims, characterized in that said enclosure (2) is provided at the level of the drying section (6B) lifting means (16) granular products circulating in said enclosure (2), the lifting means (16) being adapted to lift and release said granular products during their circulation in said enclosure (2) to form a curtain of granular products capable of absorbing a quantity of heat from the drying flow (F) sufficient for the main flow temperature (P) to be kept below a critical temperature. - Treatment device (1) according to the preceding claim, characterized in that said enclosure (2) is rotatable about its longitudinal axis (Χ-Χ '), the lifting means (16) comprising at least two rows (11) contiguous lifting buckets, said buckets being distributed for each row (11) over at least the majority of the circumference of said enclosure (2), and being designed to lift the granular products circulating in said enclosure (2) during the rotation of it,

- Treatment device (1) according to the preceding claim, characterized in that the enclosure (2) comprises an annular dike (12) for separating rows (1) of bucket interposed between two rows (11) of contiguous buckets said at least one annular dam (12) being designed to limit the flow of granular products from one row (11) of buckets to the other.

Treatment device (1) according to any one of the preceding claims, characterized in that it comprises a derivative flow sampling device (D) comprising:

at least one sampling aperture (13) of the derived stream (D) formed at the periphery of said enclosure (2) at the second branch (8B),

- an annular skirt (14) extending between an inner edge (14A) and a free portion (14B), the annular skirt (14) being attached by the inner edge (14A) inside said enclosure (2) upstream of said at least one sampling opening (13) in consideration of the flow direction (C) of the granular products, the free portion (14B) remotely covering at least a majority of said at least one sampling opening (13) ,

- At least one dam blade (15) attached to the interior of said enclosure (2), arranged helically with respect to the longitudinal axis (Χ-Χ '), and disposed downstream of said at least one opening of sampling (13) in consideration of the direction of circulation (C) of the granular products. - Processing device (1) according to any one of the preceding claims, characterized in that the first branch (8A) is connected to said enclosure (2) at or upstream of the main entrance (3A) in consideration of the direction of flow (C) of the granular products. - A method for controlling the temperature of volatile emissions produced by a device for treating (1) hot granular products, such as pebbles or aggregates, comprising:

- heating means (5) which is located inside said enclosure (2), and which is designed to generate a drying flow (F) oriented against the flow direction (C), and through a drying section (6B) of the enclosure (2), the drying stream (F) being able to contribute to the drying of said granular products within the drying section (6B),

a main evacuator (7A) of volatile fumes produced inside the enclosure (2), the main evacuator (7A) being connected to said enclosure (2) by a first branch (8A) and being designed to evacuate from the enclosure (2) a main flow (P) of fumes,

said method comprising a step in which a derivative stream (D) of fumes produced inside said enclosure (2) is taken at the drying section (6B), upstream of the first branch (8A) in consideration of the drying flow (F), and during which the derivative flow (D) is transmitted to said main evacuator (7A), the method being characterized in that it comprises a step during which one increases or reduces the flow rate of the derived flow (D) transmitted to the main evacuator (7A) according to the temperature of the main flow (P). - Control method according to the preceding claim, characterized in that increases the flow rate of the derivative flow (D) transmitted to the main evacuator (7A) when the temperature of said main flow (P) is less than a set temperature, and in that the flow rate of the derived flow (D) transmitted to the main evacuator (7A) is reduced when the temperature of said main flow (P) is higher than the set temperature. - Control method according to any one of claims 11 or 12, characterized in that it comprises a step during which is introduced granular products from the recycling of bituminous products in said enclosure (2) between the main entrance (3A) and the output (4). - Control method according to the preceding claim, characterized in that the granular products from the recycling of bituminous products into the enclosure (2) are introduced between the level at which the derived stream (D) is taken and said heater (5).