The present invention relates to a plant for transforming into secondary raw material, or for disposing of used tyres, in particular a continuous cycle plant for transforming into secondary raw material, or for disposing of, by means of pyrolysis, used tyres made of rubber or other carbon matrices.

In the prior art continuous cycle plants are known for disposal by means of pyrolysis of organic or carboniferous materials.

FR2877427 discloses a plant for treating organic materials operating on a continuous cycle. The plant further comprises a kiln provided with a body inside witch a temperature is maintained that is able to ensure pyrolysis and conveying means that describe a closed circuit and that ensure conveying of the organic solid material to be treated by containers inside which the previously shredded solid organic material arrives by the force of gravity from distributing means. The plant further comprises, in addition to the hydraulic seals located respectively in the entrance zone to the kiln of the material to be treated and in the exit zone from the kiln of the treated material.

FR2877427 has the drawback that the organic material to be treated has to be previously shredded, which entails, in particular in the case of tyres, a considerable expenditure of energy for the shredding operation. Further, the fact that the material to be treated is delivered to the pyrolysis kiln inside suitable containers means that also the latter are heated during the pyrolysis process, which entails a further expenditure of energy, in addition to the expenditure due to the cost of the containers, which have to be of refractory material that is able to withstand the high temperatures found inside the pyrolysis kiln. Further, a system with containers, like the one disclosed in FR2877427, although it appears easy to make is not in reality, in fact the working conditions of continuous cooling-heating and transition through the hydraulic seals entail great limitations to the material that is usable to make the containers. Further, the continuous passage through the hydraulic seals with the carriages entails, on the one side, a significant expenditure and on the other side a significant removal of fluids from and to the system, greatly decreasing efficiency or making the efficacy of the seals poor. Further, the carriages, at the exit from the reactor, contain not only rejects but also the seal liquid from which the rejects have to then be separated.

One object of the invention is to provide a plant for continuous-cycle treatment of used tyres by pyrolysis, that does not require costly tyre-shredding operations or require the use of suitable containers for conveying the tyres to the kiln in which treatment by pyrolysis occurs.

The object of the invention is achieved by a plant according to claim 1. Owing to the invention it is possible to treat with a continuous cycle by means of pyrolysis who tyres or tyres cut into a most two parts without it being necessary to use suitable containers to convey the tyres inside the treatment chamber. This enables considerable energy saving to be obtained and a secure maintenance of the seals and thus of the pyrolysis compared with known prior-art plants.

Some methods of carrying out the invention are disclosed below with reference to the attached drawings, in which:

Figure 1 is a schematic view of a first embodiment of a plant according to the invention; Figure la is an enlarged detail of Figure 1;

Figure 2 is an enlarged detail of Figure 1;

Figure 3 is further enlarged detail of Figure 1;

Figure 4 illustrates a detail of a version of the plant in Figure 1, in a first operating situation; Figure 5 illustrates the same detail as Figure 4, in a second operating situation;

Figure 6 is a schematic view of a second embodiment of a plant according to the invention; Figure 7 is a top view in a longitudinal section of the plant in Figure 6;

Figure 8 is an enlarged detail of Figure 6;

Figures 8a and 8b are further enlarged details of Figure 6;

Figure 9 is a further enlarged detail of Figure 6;

Figure 10 is a schematic view of a third embodiment of a plant according to the invention; Figure 11 is a top view in a longitudinal section of the plant in Figure 10;

Figure 12 is an enlarged detail of Figure 10;

Figure 13 is the section XIII-XIII of Figure 12;

Figure 14 illustrates a first heating system of the pyrolysis chamber of the plant according to the invention;

Figure 15 illustrates a second heating system of the pyrolysis chamber;

Figure 16 illustrates a version of the first heating system of the pyrolysis chamber;

Figure 17 is a schematic view of a fourth embodiment of a plant according to the invention; Figure 18 is the section A- A of Figure 17.

In Figures 1 to 3 there is illustrated a first embodiment of a plant 1 according to the invention.

The plant 1 comprises a first section 2 preparing and supplying the used tyres P to be treated and a second section 3 in which the tyres are treated.

The first section 2 comprises a first conveying device 4, for example a belt conveyor, by means of which the tyres P to be treated are conveyed to a cutting device 5, for example to a cutting device by shearing, or circumferal cutting, in which each of the tyres P is divided into two halves M, with a cut made along a diametral plane of the tyre P, or along the circumference, i.e. along a plane that is perpendicular to an axis A of the tyre P, in such a manner that each half M' has the form of a "C", or of a "doughnut". Below, said halves M, M' will be called semi-tyres M, M'.

At the outlet of the cutting or punching device 5, if along the diameter the semi-tyres M are cut, the semi-tyres M that are obtained from each tyre P are oriented in opposite directions and are conveyed from the first conveying device 4 to an orienting device 6, which orients all the semi-tyres M in the same direction .

From the orienting device 6, the semi-tyres M move to a second conveying device 7, which is for example also a belt conveyor, which conveys the semi-tyres M to a transferring device 8, for example a strap transferring device, that transfers groups G of semi-tyres to a compacting and binding device 9, in which the group G of semi-tyres M is compacted by a compacting element 10 and the semi-tyres M of the group G are bound together so as to constitute a compact assembly. The groups G of compacted and bound semi-tyres can be superimposed and fixed together, for example by binding, so as to form units U consisting of two or more groups G, that enable space to be save in the pyrolysis chamber 11.

The tyres P, or the semi-tyres M, M', or the units U are conveyed, by a third conveying device 12, to a delivery device that comprises a chute 13 tilted downwards, that delivers the tyres P, the semi-tyres M, M', or the units U to a tank 14 containing a liquid L, for example water or oil, and by a conveying device 15 that transfers the tyres P, the semi-tyres M, M', or the units U from the tank 14 to the pyrolysis chamber 11. The tank 14 constitutes a hydraulic seal to the entrance of the pyrolysis chamber 11 , to prevent the heat generated inside the pyrolysis chamber 11 being dispersed outside and to prevent polluting gases and solid particles moving in an uncontrolled manner from the pyrolysis chamber 11 to the external environment.

In the tank 14 an end of the conveying device 15 is arranged, for example a belt conveyor, that conveys the tyres P, the semi-tyres M, M', or the units U outside the tank 14, inside the pyrolysis chamber 11. The conveying device 15 comprises a tilted portion 15a along which the tyres P, the semi-tyres M, M', or the units U are conveyed from the tank 14 to the pyrolysis chamber 11. The angle of tilt of the tilted portion 15a is chosen in such a manner that the tyres P, the semi-tyres M, M', or the units U can slide downwards.

If in the pyrolysis chamber 11 whole tyres P are conveyed, it is advantageous that a hole 81 is made in the tyres P by the cutting or punching device 5 before the tyres P are delivered to the tank 14. The hole 81 is used to evacuate the air from the tyres P, when they are delivered to the tank 14 and to evacuate therefrom the liquid L when the tyres are extracted from the tank 14 and sent to the pyrolysis chamber 11.

The speed of the conveying device 15 is adjusted in such a manner that the pyrolysis treatment is completed before the material to be treated has reached the end of the conveying device 15 located on the opposite side to the entrance of the pyrolysis chamber 11. At the end of the pyrolysis treatment the residual material 51 consists of carbon particles 18 and of metal filaments 17, which are normally found in the tyre carcasses. Said residual material can be conveyed by the conveying device 15 to a further tank 20 containing a liquid L, for example water or oil, which constitutes a further hydraulic seal at the exit of the pyrolysis chamber 11 to prevent the heat generated inside the pyrolysis chamber 11 being dispersed outside and to prevent polluting gases and solid particles moving in an uncontrolled manner from the pyrolysis chamber 11 to the external environment.

The fragments 17, in the further tank 20, are collected by an evacuating device 21, for example a belt conveyor device, which conveys the fragments 17 outside the tank 20.

The pyrolysis chamber 11 is provided with an evacuating conduit 50, through which the gases produced during pyrolysis are evacuated.

The first tank 14 is connected, via a first conduit 37 to a filtering tank 36, in which particles of material of the tyres P released in the liquid L are filtered together with the carbon particles 18 discharged into the tank 20 via the conveying device 15. Also the further tank 20 is connected to the filtering tank 36 by a second conduit 38. The filtering tank 36 is provided above with a filter 43 that is suitable for retaining in the upper part 36a of the filtering tank 36 the solid particles found in the liquid L coming from the tank 14 and from the further tank 20.

The filtered liquid L is collected in the lower part 36b of the filtering tank 36 and is recirculated in the tank 14 by means of a third conduit 39 and a first recirculating pump 40 and in the further tank 20 by means of a fourth conduit 41 and a second recirculating pump 42.

In Figures 4 and 5 a version of the plant of Figures 1 and 3 is illustrated in which with the tilted portion 15a of the conveying device 15 a first heat barrier 32 and a second thermal barrier 35 are associated, the function of which is to minimise the quantity of heat that is transmitted by the pyrolysis chamber 11 to the liquid L, thus permitting a significant energy saving and considerably reducing the quantity of steam that forms because of the evaporation of the heated liquid L.

The first heat barrier 32 comprises a tilting element 32a, having, for example, a semi-lunar cross section and a width that is at least as great as the width of the conveying device 15. The tilting element 32a is made of a thermally insulating material. The tilting element 32a can rotate freely around a rotation axis 33, between a first operating position, shown in Figure 4, in which the tilting element 32a covers almost completely the free surface of the liquid L, isolating the liquid L from the heat coming from the pyrolysis chamber 11, and a second operating position shown in Figure 5. When the tyres P, the semi-tyres M, M\ or the units U conveyed by the conveying device 15 come into contact with the tilting element 32a they push the tilting element 32a upwards, rotating the tilting element 32a around the rotation axis 33 in said second operating position, so as to be able to pass beyond the tilting element 32a, continuing along said tilted portion 15a.

The tilting element 32a is associated with a stop element 34 that defines the first operating position of said tilting element 32a.

The second thermal barrier 35 consists of a plurality of elements 35a in the shape of strips that are parallel to one another, which are placed at the entrance to the pyrolysis chamber 11 and are arranged perpendicularly to the advance direction of the conveying device 15. The elements 35a are fixed above to the ceiling 1 la of the pyrolysis chamber 11, are at least as wide as the conveying device 15 and are made of a flexible material that is resistant to heat, for example a heat-resistant fabric.

The first heat barrier 32 and the second thermal barrier 35 can also be used in isolation. It is further advantageous to provide a further thermal barrier made with a layer 19 (Figure 10) of refractory material in granular form with a low specific weight below the specific weight of the liquid L, for example expanded clay, distributed over the free surface of the liquid L. This further thermal barrier can also be used in isolation.

In Figures 6 to 9 a second embodiment of a plant 1 a according to the invention is illustrated. Parts of the plant 1 a corresponding to parts of the plant 1 illustrated in Figures 1 to 3 are indicated by the same reference numbers.

In this second embodiment the tyres P, conveyed by a first conveying device 4, for example a belt conveyor, are first conveyed to a bead breaker 24, i.e. a device in which the beads T of the tyres are removed to facilitate subsequent cutting of the tyres. The tyres P, devoid of the bead, are then conveyed by the first conveying device 4 to the cutting or punching device 5, in which in each of the tyres P a transverse cut TA along a diametral plane, and a plurality of incisions I along further diametral planes are made, as illustrated in Figure 8a, so as to be able to extend each tyre P on a plane, as illustrated in Figure 8b. At the exit of the cutting device 5, the tyres P are oriented correctly for entry into the loading system. Alternatively, the tyres P can be cut along the circumference, so as to obtain two halves, or semi-tyres, M' in the form of a "doughnut" or two halves, or semi-tyres M in the form of a "C".

The tyres P, or the semi-tyres M, M' are conveyed to the pyrolysis chamber 11 by a conveying device 26 that extends through a channel 25, partially full of a liquid L, for example water or oil, that flows in a pyrolysis chamber 11. The channel 25, that constitutes a hydraulic seal at the entrance to the pyrolysis chamber 11 , is defined between an upper wall 27 and a lower wall 28 and is filled with the liquid L up to a level that is sufficient for preventing the heat generated inside the pyrolysis chamber 11 being dispersed outside and preventing polluting gases and solid particles moving in an uncontrolled manner from the pyrolysis chamber 11 to the external environment. The conveying device 26 comprises a first series of upper motor-driven rollers 29, or a first upper motor-driven belt, and a second series of lower motor-driven rollers 30, or a second lower motor-driven belt, arranged inside the channel 25, between which the tyres are conveyed P, or the semi-tyres M, M', which transit in a space S, dragged by friction by said upper rollers, 29 and said lower rollers 30, or by said upper motor-driven belt and said lower motor-driven belt. In an initial portion 26a of the conveying device 26, the first and second series of motor-driven rollers, or the first or the second conveyor belt, can be arranged along convergent directions, for facilitating the entry of the tyres P, or of the semi-tyres M, M', into the conveying device 26, as shown in Figure 8.

At the exit of the channel 25, inside the pyrolysis chamber 11, the conveying device 26 deposits the tyres P, or the semi -tyres M, M', onto a further conveying device 31, for example a belt conveyor, that conveys the tyres P, or the semi-tyres M, M' through the pyrolysis chamber 11. The speed of the further conveying device 31 is adjusted so that the pyrolysis treatment is completed before the material to be treated has reached the end of the further conveying device 31 placed on an opposite side with respect to the exit of the channel 25. At the end of the pyrolysis treatment the residual solid material 51 consists of carbon particles 18 and of metal filaments 17, which are normally found in the tyre carcasses.

The carbon particles 18 and the metal filaments 17 are discharged into a collecting area 45 of the pyrolysis chamber 11, which communicates with a removable collecting receptacle 44. Between the collecting area 45 and collecting receptacle 44 there are interposed a first valve 46, for example a first gate valve, and a second valve 47, for example a second gate valve, between which a space 48 is defined that is used for transferring to the collecting receptacle 44 the residual solid material 51 that is collected in the collecting area 45. The space 48 communicates with a conduit 49 to which nitrogen can be delivered to prevent gases produced by the pyrolysis process penetrating the collecting receptacle 44 during the transfer of the residual material 51 from the collecting area 45 to the collecting receptacle 44, as will be explained below, or for preventing air being able to penetrate from the external environment to the pyrolysis chamber 11. Instead of the collecting receptacle 45 a conveyor belt can be provided onto which to discharge said residual solid material.

To transfer the residual solid material 51 from the collecting area 45 to the collecting receptacle 44, or to the conveyor belt, the first valve 46 opens, keeping the second valve 47 closed, so that the residual solid material 51 can enter the space 48. The first valve 46 then closed, simultaneously injecting nitrogen into the space 48, by means of the conduit 49, to prevent the gases in the atmosphere being able to enter the space 48, and the second valve 47 opens so that the residual material 51 that had filled the space 48 can drop by the force of gravity into the collecting receptacle 44, or onto the conveyor belt. Lastly, the second valve 47 closes again and the cycle can be repeated. In Figures 10 to 13 there is illustrated a third embodiment of a plant lb according to the invention.

Parts of the plant lb corresponding to parts of the plant 1 illustrated in Figures 1 to 5, or to parts of the plant la illustrated in Figures 6 to 9, are indicated by the same reference numbers.

In this third embodiment the tyres P can be placed on a first conveying device 52, for example a belt conveyor that may be provided with baffles 53 between which the tyres P are arranged. The first conveying device 52 conveys the tyres P to a cutting device 54, in which each of the tyres P is divided into two semi-tyres M' with a cut made along a plane that is perpendicular to an axis A of the tyre P.

At the exit of the cutting device 54, the semi-tyres M' are conveyed by the first conveying device 52 to a further conveying device 55, for example an overhead conveying device, that comprises a closed-loop conveying cable or chain 58, to which are fixed, for example at constant intervals, the supporting elements 59 to which the semi-tyres M' are suspended. The further conveying device 55 conveys the semi-tyres M' through a tank 56 containing a liquid L, for example water or oil, that constitutes a hydraulic seal at the entrance to the pyrolysis chamber 11, to prevent the heat generated inside the pyrolysis chamber 11 being dispersed outside and to prevent polluting gases and solid particles moving in an uncontrolled manner from the pyrolysis chamber 11 to the external environment.

Exiting the tank 56, the semi-tyres M' are delivered to the pyrolysis chamber 11, inside which they are delivered by the further conveying device 55 to a still further conveying device 57, for example a belt conveyor, which may be provided with baffles 53 between which the semi-tyres M' are arranged.

The still further conveying device 57 conveys the semi-tyres M' through the pyrolysis chamber 11. The speed of the still further conveying device 57 is adjusted in such a manner that the pyrolysis treatment is completed before the material to be treated has reached the end of the further conveying device 57 placed on an opposite side with respect to the tank 56. At the end of the pyrolysis treatment the residual solid material 51 consists of carbon particles 18 and of metal filaments 17, which are normally found in the tyre carcasses. As in the second embodiment of the plant according to the invention, disclosed previously, the carbon particles 18 and the metal filaments 17 are discharged into a collecting area 45, which communicates with a collecting receptacle 44, or discharged from the collecting area 45 on a conveyor belt, which is not shown.

In Figure 14 a first heating system of the pyrolysis chamber 11 is illustrated schematically that uses the gases produced in the pyrolysis process to heat the pyrolysis chamber 11.

The gases produced in the pyrolysis chamber 11 are sent, through the evacuating conduit 50, to a first conduit 63, that conveys the gases to the combustion chamber 67 in which said gases, which contain a significant quantity of combustible substances, are burnt. The fumes produced by the combustion of said gases are sent, by a second conduit 61, to a gap 60 of the pyrolysis chamber 11, to heat, by radiation, the inside of the pyrolysis chamber 11. The fumes, which are still at high temperature, near the temperature inside the pyrolysis chamber, i.e. hundreds of degrees, are evacuated from the gap 60 through an evacuating conduit 62, provided with a pump 66, that extracts the fumes from the gap 62 and sends them to a heat exchanger 64, in which a liquid or gas fluid, sent to the exchanger by a further pump 65, is heated to be then sent via a third conduit 69 to a user 70.

In Figure 15 a second heating system of the pyrolysis chamber 11 is illustrated schematically that uses the gases produced in the pyrolysis process to heat the pyrolysis chamber 11.

The gases produced in the pyrolysis chamber 11 are extracted through the evacuating conduit 50, by a pump 75 that sends them to a three-way valve 65, by means of which they can be delivered to a second conduit 73 and to a third conduit 66. The second conduit 73 conveys the gas through a heat exchanger 64, in which the gases are heated by fumes coming from a combustion chamber 67. The aforesaid gases, after traversing the heat exchanger 64, are sent, via the second conduit 73 to an inlet 72 of the pyrolysis chamber 11, to heat the inside of the latter by convection. The third conduit 66 conveys the gas to the combustion chamber 67 in which said gases, which contain a significant quantity of combustible substances, are burnt. The fumes produced by the combustion of said gases are sent, by means of a fourth conduit 69 to the heat exchanger 64 in which they are used to heat the gases that transit in the second conduit 73. Exiting the heat exchanger 64, the still hot fumes produced by the combustion of said gases in the combustion chamber 67, are sent to a possible user 70 who uses the residual heat of the fumes.

The combustion chamber 67 is supplied with comburent gas, for example air, through a supply conduit 68.

This second heating system of the pyrolysis chamber 11 is more efficient than the first system disclosed previously because the heat required to conduct the pyrolysis process is transmitted by convection rather than radiation, inside the pyrolysis chamber.

In Figure 16 there is illustrated a version of the first heating system of the pyrolysis chamber 11, that arranges, in the gap 60 of the pyrolysis chamber 11, a plurality of electrical resistances 73, by means of further heat is supplied, by radiation, to the pyrolysis chamber 11.

In said first heating system illustrated in Figures 14 and 16, it is advantageous that the pyrolysis chamber 11 has a shape such as to optimise the transmission of heat by radiation to the material to be treated. For example, the pyrolysis chamber can have a semicylindrical shape. In Figures 17 and 18 a fourth embodiment of a plant according to the invention is illustrated. Parts of the plant corresponding to those illustrated with reference to the preceding versions are indicated by the same reference numbers.

In this fourth embodiment, at the exit of the pyrolysis chamber 11 the carbon particles 18 and the metal filaments 17 are discharged into a collecting area 80, that can be closed below by a first movable baffle 74 which is rotatable, by driving means that are not shown, around a rotation axis 75. The first movable baffle 74 can be rotated around a rotation axis 75, between a closed position, shown as a continuous line in Figure 17 and indicated by the reference number 74a, and an open position shown by a dashed line and indicated by the reference number 74b. In the closed position 74a, the first movable baffle 74 constitutes the bottom of the collecting area 80, on which is deposited the residual material 51 resulting from the pyrolysis treatment, consisting of the carbon particles 18 and of the metal residues 17.

At preset intervals of time, the first movable baffle 74 is rotated from the closed position 74a to the open position 74b. When the first movable baffle 74 is rotated to the open position 74b the residual material 51 falls into the further tank 20 and is collected by a second movable baffle 76, which can rotate around a rotation axis 77, between a non-operating position 76a, indicated by a dashed line in Figure 17, a first operating position 76b, indicated by a continuous line, and a second operating position 76c, indicated by dashed line.

When the first movable baffle 74 is rotated in the open position 74b, the second movable baffle 76 is rotated from the non-operating position 76a to the first position 76b, to collect the residual material 51 coming from the collecting area 80. After collecting the residual material 51 , the second movable baffle is rotated to the third operating position 76c, so as to drop the metal residues 17 onto the evacuating device 21 , which conveys them outside the further tank 20. Simultaneously, the rotation movement of the second movable baffle 76 to the third operating position 76c pushes the carbon particles to the free surface of the liquid L contained in the further tank 20.

The further tank 20 is further provided with a third movable baffle 78, provided with a raised edge 82, which is rotatable around a rotation axis 79. During rotation thereof around the rotation axis 79, the third movable baffle collects, acting like a blade, the carbon particles 18 emerging on the free surface of the liquid L and conveys the carbon particles 18 outside the further tank 20, for example to a collecting container that is not shown.

In the practical embodiment the features of the invention can be different from those illustrated previously but be technically equivalent thereto without falling outside the scope of the present invention.