Plant for producing bituminous conglomerate in continuous work cycle

Abstract: The invention refers to a closed operative plant consists of a cylindrical rotary kiln (6-7) with upper filtering unit (34) for the smokes to be used for producing bituminous conglomerate. Said cylindrical kiln with initial part of smaller diameter (6), forming the drying chamber (16), and subsequent part of larger diameter (7), forming the combustion chamber (17), foresees in its inner a cylindrical structure (21) with fixed duct, brought on header (22), which lets in the heat flow from the burner (32) to the combustion chamber (17) countercurrent compared to the direction of advancement of the inert product. Inside the cylindrical kiln is then foreseen a mixing chamber (23) formed by a closed unit lying behind the wall where is placed the inlet of the heat flow. Moreover it is foreseen the unloading of the product ready to be used from the mixing chamber (23) by means of three hydraulic cylinder (28) which open a set of equidistant portholes (29). The filtering unit consists of a closed cycle realizing the blasting of the smokes purified by means of fabric filters (37). The purifies air is then unloaded outdoor passing through a stack 40 using an intake manifolt (38) with air propeller (39). Moreover it is foreseen the coming into che mixing chamber (23) of the recovery fine dust of cement together with nonasphaltic road oil at 140°, coming from a feeder by means of a duct (25), and with other material made by fine dust of cement acting as binder coming from a screw conveyor (26) coaxially placed around the duct (25).

Description: The invention refers to a plant consists of a cylindrical rotary furnace and of a filter for the smokes to be used for producing bituminous conglomerate in continuous cycle. Said cylindrical furnace consists of an initial part of smaller diameter, forming the drying chamber, and of an other part of larger diameter and it provides in its inner a cylindrical structure with fixed duct, brought on head, which lets in the heat flow from the burner to the combustion chamber countercurrent compared to the way of advancement of the inert product. Inside the cylindrical furnace a mixing chamber is then provided. It consists of a closed unit lying behind the wall where is placed the inlet of the heat flow. Moreover the unloading of the product ready to be used from the mixing chamber of the furnace to a programmed time is provided. The filter realizes the blasting of the smokes with continuous unloading towards outside of the purified air. Said filter makes the total recovery and dosing of the fine dust of the cement suspended in the air flow for its prompt use into the mixing chamber. Moreover the filter permits the complete use of the heat flow acting into a closed cycle. According to the prior art is know the plant described and shown in the Italian Patent Application BO91A 000487. In comparison with said plant the invented plant providing the heat flow countercurrent compared to the direction of advancement of the inert product into the drying and and combustion chmbers permits, for contact, to increase the heat exchan ge effect so assuring a better yield of the furnace. Being the combustion chamber provides in a closed unit, thanks to the different placing of the unit generating the heat flow, it is avoided the product volatization in particular of the fine dust of the cement and it is permitted to keep the product mixing to a right dosing. The invented cylindrical furnace with its inital part of smaller diameter, contrary to the furnace described in the italian document BO91A 000487 with an unchanged diameter, permits to actuate the widths of the drying and combustion chambers related to the use necessities; this considering that into the drying chamber is prevalent necessary to move the product onto the wall to increase the licking up effect while into the combustion chamber is prevalent the necessity to bring the product onto the heat source. In the plant described in the Italian document BO91A 000487 the unloading of the product ready to be used from the mixing chamber is actuated in continuous way according to the casuality so determining heterogeneous product. The invented plant is provided with programmed times for the unloading to avoiding heterogeneous product. Moreover the invented plant permits the complete recovery and dosing of the fine dust of cement for its prompt re-use. Providing the invented plant an isolated filter consists of a closed unit and acts following to the cylindrical rotary furnace, it is possibile to realize the blasting of the smokes present into the circulation air and also to realize the complete use of the plant heat. Moreover being actuated the feeding of the bitumen in the mixing chamber, where there is not a circulation flow, is avoided the dispersion of the same bitumen and consequently it is avoided the air pollution. Other apparatuses are known, as for instance the apparatuses described and shown in the documents US-A-4 211 490 and US-A-54 054 931. The invented plant consists of a cylindrical rotary furnace in continuous cyle with upper filter. Said plant brought on a frame with three bridges 1 completed with a bearing structure 2. Said structure 2 provides beams 3, slanting towards the unloading, which bring on couple of rotaring bearings 4 with rollers 5 a cylindrical furnace with initial part of smaller diameter 6 and other part of larger diameter 7. Said furnace having emerging on its outside rims 8 for the contact of the rollers 5 with motion given by a motor 9 which trasmits on the gear 10 of the rotary support 11 to the rack 12. The inert product, after to have being dosed, from the elevator 13, through the inlet 14 present on the transversal fixed wall 15, coming into the drying chamber 16 formed by the inital part of smaller diameter 6 of the furnace. In said drying chamber the product, in continuous movement by means of the vanes, goes on gradually by gravity effect and it arrives into the combustion chamber 17 formed by the other part of larger diameter 7 of the cylindrical furnace. At the end of said combustion chamber the product climbs on a rotary elevator equipped with vanes 18 radially placed on the circular crown 19 emerging from the cylindrical furnace 6-7. Said crown 19 rotates together with the furnace and it forms, with the inner circular fixed part 20 centrally brought by a cylindrical structure 21 housing into the fixed frame 22 sets out on the bearing structure 2, an orifice plate which devides the combustion chamber from the mixing chamber 23. The inert product, after to have being dryed into the drying chamber 16 and to have being baked into the combustion chamber 17, climbs by means of the vanes 18 and it is unloaded in continuous cycle by means of the chute 24 into the mixing chamber 23. In said mixing chamber, through a duct 25, is let in nonasphaltic road oil at 140° coming from a feeder. Contemporary through a screw conveyor 26, coaxially placed around the duct 25, is unloaded into the mixing chamber 23 other material made by fine dust of cement coming from an other feeder and acting as binder. The mixing is facilitated by vanes 27 placed in parallel on the wall mixing chamber 23. To better mix the product it is provided its intermittent unloading. The intermitted unloading actuated by three hydraulic cylinders 28 equipped with timers to regulate the operating times. The hydraulic cylinders 28 open equidistant portholes 29 for the unloading of the product ready to be used which goes on in continuous and is unloaded through the opening 30 of the hopper 31. The product going out from the hopper 31 is then loaded on transport means or used for the different necessities. The cylindrical rotary fornace 6-7 uses a burner 32 which, through a duct provided into the cylindrical structure 21, lets in the flame into the cylindrical furnace through the mouth 33 creating a heat flow countercurrent compared to the material advancing into the drying chamber 16 and into the combustion chamber 17. Upper to the cylindrical furnace, always supported by the bearing structure 2, a parallelepipedal filter 34 is provided with separators 35 which divide the inside space in sectors 36 equipped with fiber filters 37. An intake manifold 38 with air propeller 39 is used for the getting out of the air purified by smokes through the stack 40. With the inert product into the combustion chamber 17 run into the heat jet coming out from the mouth 33, through the collector 41 housing into the head 42, the smokes sucked up by the air propeller 39 pass into an upper duct 43 and coming into a pre-separator 44. Said smokes then arrive into the chamber 45 where, going through the fiber filters 37, are purified. The purified air goes out from the duct 46 and through the intake manifold 38 by the air propeller 39 goes out from the stack 40. The dusts which have being kept into the fiber filters 37 fall into the cone-shaped duct 47 with at its end the Archimedes'screw 48. Said Archimedes' screw 48 unloads the dusts into a duct 49 with a Archimedes' screw 50 where the load cells 51 of fine recovery product are weighed. The Archimedes' screw 50 then unload the fine recovery product into the mixing chamber 23 through the screw conveyor 26. In this way is realized the prompt re-use of the fine dust of cement dispelled into the plant. The invented plant is illustrated in schematic view in the drawings of sheets 1, 2, 3 and 4. Fig. 1 is longitudinal section view of the plant in its initial part with view of the cylindrical furnace 6-7 and of the upper filter 34. Fig. 2 is longitudinal section view of the plant in its end part with view of the mixing chamber 23. Fig. 3 is back view of the plant. Fig. 4 is side view of the plant with view of the frame with three bridges 1.

Claims: Plant for producing bituminous conglomerate in continuous work cycle, comprising a closed operative plant supported on a frame with three aligned bridges (1) completed with a bearing network structure (2) with beams (3), slanting towards the unloading side, which structure supports, on couple with rotary bearings (4) with rollers (5), a cylindrical rotary furnace (6-7), into which inert product coming from an elevator (13) is fed, and above the cylindrical furnace, always supported by the network structure (2), a parallelepipedal filtering unit (34); the cylindrical furnace (6-7) consisting of an initial part of smaller diameter (6) forming a drying chamber (16) and of a subsequent part of larger diameter (7) forming a combustion chamber (17); in said drying chamber (16) the product, moved by sets of vanes, proceeds due to gravity effect to come into the combustion chamber (17), at the end of which the product climbs on a rotary elevator equipped with a set of vanes (18) and is unloaded in continuous work cycle by means of a chute (24) into a mixing chamber (23), where nonasphaltic road oil at 140° is let in through a duct (25) and where other material made of fine dust of cement is let in through a screw conveyor (26), and from which the product ready to be used is unloaded by means of a hopper (31); the cylindrical furnace (6-7) using a burner (32), which, through a duct provided in a cylindrical structure (21), lets in a flame through a mouth (33), thereby creating a heat flow countercurrent compared to the material advancing into the drying chamber (16) and into the combustion chamber (17); to better mixthe product its intermittent unloading being actuated by three hydraulic cylinders (28) equipped with timers for regulating the operative times, said cylinders (28) open a set of equidistant portholes (29) for the unloading of the product ready to be used which proceeds in continuous way; the filtering unit (34) providing separators (35) which divide inside sectors (36) equipped with sets of fabric filters (37), and providing an intake manifold (38) with an air propeller (39) for getting out the purified air through a stack (40); a prompt re-employment of the fine dust of cement kept by the fabric filters (37) being realized in that the dust falls into a cone-shaped duct (47) having at its end an Archimedean screw (48), which screw (48) loads said dust into a duct with an Archimedean screw (50), which re-puts the dust into the mixing chamber (23) through a screw conveyor (26). Plant according to claim 1, characterized in that the cylindrical furnace (6-7) is provided on its outside with rims (8) for contact with the rollers (5), the motion being given by a motor (9) and being transmitted via a gear (10) on a support (11) to a rack (12). Plant according to claim 1, characterized in that the set of vanes (18) is radially placed on a circular crown (19) emerging from the cylindrical furnace (6-7), and in that said crown (19) rotates together with the furnace to form, with the inner circular fixed part (20) brought centrally by a cylindrical structure (21), an orifice plate which divides the combustion chamber (17) from the subsequent mixing chamber (23). Plant according to claim 1, characterized in that the mixing in the mixing chamber (23) is facilitated by sets of vanes (27) placed in parallel on the wall of the mixing chamber (23). Plant according to claim 1, characterized in that the product going out from the hopper (31) is then loaded on transport means or used for different necessities. Plant according to claim 1, characterized in that the smokes of the inert product in the combustion chamber (17) run into the heat jet coming out from the mouth (33), then through a collector housing (41) into the header (42), the smokes then being sucked up by the air propeller (39) and pass an upper duct (43), then come into a pre-separator (44) and then arrive in a chamber (45), where they, while going through the fabric filters (37), are purified. Plant according to claim 1, characterized in that the last Archimedean screw (48) unloads the dusts into a duct (49) with an Archimedean screw (50), where the load cells (51) of fine recovery product are weighed.

Inventors: GHIRARDELLI GIORGIO, GHIRARDELLI, GIORGIO
Applicants: GHIRARDELLI GIORGIO, GHIRARDELLI, GIORGIO
Application year: 1993
Main classification: E01C19
IPC codes: E01C19