AU2252300A

AU2252300A - Installation for processing waste by means of thermolysis with transport means in an inert atmosphere

Info

Publication number: AU2252300A
Application number: AU22523/00A
Authority: AU
Inventors: Patrick Lefevre; Philippe Milles
Original assignee: Francaise de Thermolyse Ste
Current assignee: Nexus Technologies SAS
Priority date: 1999-02-25
Filing date: 1999-02-25
Publication date: 2000-09-14
Also published as: KR20010042975A; WO2000050536A1; EP1078024A1; CA2326234A1; CN1298436A; JP2002542133A; BR9909884A

Description

1 Installation for the treatment of waste by thermolysis with transport means under an inert atmosphere 5 The present invention relates to an installation for the treatment of waste by thermolysis. There is already known, according to document EP-A-0 505 278, a system for the treatment of solid products the discarding of which may damage the environment, comprising a reactor incorporating, in order, a dehydration 10 chamber, a thermolysis chamber and a cooling chamber downstream from the thermolysis chamber. The chambers are isolated from one another in a substantially tight manner, by guillotine doors operated by jacks; the door between the dehydration and thermolysis chambers and the door between the thermolysis and cooling 15 chambers are mobile vertically in tight housings, the crossing of the lifting jacks being carried out by stuffing-box. In addition, tight doors are provided at the entrance to the dehydration chamber and at the exit from the cooling chamber, thanks to which the dehydration and cooling chambers are, at will, isolated vis-6 vis the outside and/or the thermolysis chamber. A limit is thus set to the entries of 20 air into the thermolysis zone during the introduction of the products and during the extraction of the residues. Thus there is alternately, as required, an isolation of the dehydration chamber from the thermolysis chamber when the products are introduced into the dehydration chamber, and of the thermolysis chamber from the cooling chamber when the residues are extracted from this third chamber. 25 The products to be treated are placed in carriages which pass from one chamber into the other by means of a rack-and-pinion mechanism. Such a system gives satisfaction overall. However, it is difficult to maintain and repair the technical means pertaining to the doors separating the thermolysis chamber from the dehydration 30 chamber and from the cooling chamber. The result is high maintenance and repair costs. Moreover, the presence of doors inside the reactor necessitates the use of complicated systems for moving the carriages.

2 The present invention aims in particular to overcome these disadvantages. It proposes, to this end, an installation for the thermolytic treatment of waste, comprising: 5 - a thermolysis oven, substantially horizontal and intended to receive at least one carriage receiving waste intended to be treated by thermolysis; characterized by - transport means for carriages, in order to bring each carriage loaded with waste, under an inert atmosphere, to a tight access door of the oven and 10 recover them, under an inert atmosphere, after thermolysis treatment, at this door or at a tight exit door of the oven; - means of transferring each carriage from the means of transport to the thermolysis oven and vice-versa; and - means of establishing a tight connection between the transport means and 15 the thermolysis oven during the transfer of each carriage from the transport means to the thermolysis oven and vice-versa. It is thus possible to gain direct access to the access door(s) at the thermolysis oven, without having to pass through any chamber. Moreover, there is no door obstructing the inside of the thermolysis 20 oven. The means of transport under an inert atmosphere actually serve here as a screen isolating the thermolysis oven vis-A-vis the outside, both when a carriage loaded with waste is introduced into the oven and when a carriage loaded with residues is recovered from it. In a preferred embodiment, the oven comprises means of 25 conveying several carriages in the thermolysis oven, between a tight entry door and a tight exit door. As a variant, the installation can comprise a plurality of independent chambers, each forming a thermolysis oven for a single carriage loaded with waste and each having a tight access door for the passage of the carriage, each 30 of these chambers being served by the transport means. The installation preferably also comprises a cooling zone for each of the carriages loaded with residues, fitted with a tight access door and served by the transport means.

3 The cooling of the carriages can be carried out by means of a cold gaseous fluid, nitrogen, or water. As can be seen, thanks to the present invention, it is possible to realize the installation for the thermolytic treatment of waste in the form of a 5 plurality of autonomous modules served by the transport means. The person skilled in the art thus has more freedom of design and lay-out. According to preferred provisions, the means of transport comprise at least one loader travelling on rails and defining a reception chamber, closed tight by a door, for a carriage. 10 Other characteristics and advantages of the present invention emerge from the following description, which is provided by way of a non limitative example, with reference to the attached drawings in which: - figure 1 is a very schematic plan view of an installation according to the invention; 15 - figure 2 is a very schematic plan view of a variant of the installation according to the invention; and - figure 3 is a very schematic plan view of another variant of the installation according to the invention. There is represented in figure 1 an installation for the thermolytic 20 treatment of waste, such as urban and/or industrial waste, in accordance with the present invention. It comprises in particular a zone or unit 10 for loading carriages, a thermolysis oven 20, a unit 30 for cooling residues and means 40 of transporting the carriages. The loading unit 10 is fitted with a hopper 11 for loading carriages 25 12 with waste intended to be treated in the thermolysis oven 20. The carriage 12 loaded with waste is then brought to an exit door 13 of the unit 10 or placed in a waiting position before being presented at this door 13. The waiting position is represented by the carriage 12 placed at the extreme right-hand end of the unit 10 in figure 1. 30 The carriages 12 used in the present installation can be for example of the type described in international patent application WO-98/16594, which comprise two parallel joists resting while rolling on two sets of travelling wheels.

4 These carriages 12 are then transferred, one by one, to the transport means 40 in order to be brought to the thermolysis oven 20. To this end, the transport means 40 comprise a loader 41 mounted mobile on rails 42, in such a way that the loader 41 can serve the loading unit 10, 5 the thermolysis oven 20 and the cooling zone 30. The loader 41 defines a chamber for receiving a carriage 12, closed tight by a door 43. To bring a carriage 12 to the thermolysis oven, this loader 41 presents itself before the door 13 of the loading unit 10. The doors 13 and 43 are 10 then opened and the carriage loaded with waste to be treated is transferred to the loader 41. The means permitting the transfer of the carriage from the unit 10 to the loader 41, but also from the loader 41 to the thermolysis oven 20 or vice versa and to the cooling unit 30 consist of a traction- or push-jack-operated 15 handling arm 45. The door 43 allows the loader 41 to be closed tight. It consists for example of a door transversely mobile in tight housings (register). The door 13 can also be of this type. In order to prevent air from entering the thermolysis oven 20 and 20 causing the combustion of the waste which is present there, during the transfer of a carriage from the loader 41 to this oven 20, the loader 41 is, after recovery of a carriage 12 loaded with waste to be treated, emptied of air and placed under an inert atmosphere. To do this, pumping means (not visible in figure 1) are connected to the loader 41, via a connection. The loader 41 having been emptied 25 of air with the help of these pumping means, an inert gas, such as nitrogen, is injected into the inside of the loader from a source of inert gas. As such means of creating a vacuum and injecting inert gas are well known to the person skilled in the art, they will not be described in more detail here. It will simply be noted that these means can, as a variant, be mounted directly on the loader 41. 30 Once the loader 41 is under an inert atmosphere, it is brought up opposite a tight entrance 21 of the thermolysis oven 20. Means of establishing a tight connection between the loader 41 and the thermolysis oven 20 are then deployed. In this case, these are a bellows 22 5 mounted around the door 21. These bellows 22 are in the folded state in figure 1, as the loader is situated, in this figure, opposite a tight exit door 23 of the oven 20. As can be seen in this figure 1, bellows 24, identical to bellows 22, are also mounted around the door 23 and are represented in the deployed state. 5 As a variant, inflatable elements can be used instead and in place of the bellows 22 and 24. These means of establishing a tight connection can also be mounted, if desired, on the loader 41. As needed, during the transfer of a carriage 12 from the loader 41 to the oven 20 or vice-versa, the interface between the loader 41 and the oven 10 20 can be flushed with inert gas during the transfer period. Sensors (not shown), such as load sensors making it possible to ensure that the doors 21 and 23 are well plated on the respective frames, are also provided to prohibit any opening of the doors 21 and 23, as long as a tight connection is not established between the loader 41 and the oven 20. 15 The bellows 22 are thus deployed and fit against the loader 41 to obtain a tight connection, which is then placed under an inert atmosphere. The doors 21 and 43 are then opened and the carriage 12 loaded with waste to be treated is introduced into the oven 20. In this respect, it will be noted that the doors 21 and 23 are also 20 tight doors, such as for example doors operated by jacks and transversely mobile in tight housings (registers). These doors can be horizontally or vertically mobile. Several carriages 12 travel inside the thermolysis oven between the entrance door 21 and the exit door 23. The carriages 12 are conveyed here by a push-jack chain or ratchet system. These carriages are guided by means of 25 travelling wheels and handling rollers. As far as the thermolytic treatment itself is concerned, reference may be made to the aforementioned international patent application WO-98/16 594 for more details. It will simply be noted that the thermolysis oven 20 comprises a line 30 (not visible in figure 1) supplying hot gaseous fluid, opening out into the oven 20, a line (not visible in figure 1) extracting the gases from the thermolysis oven and means of fluidic connection (not visible in figure 1) in order to establish a temporary fluidic connection between the supply line and a connection zone 6 provided on the carriage 12 and communicating with a zone receiving waste from this carriage 12. It is thus possible to inject the hot gaseous fluid directly into the load in order to carry out the thermolysis. A boiler (not shown in figure 1) is fluidically connected to the 5 extraction line and suitable for burning at least a portion of the gases which have come from the thermolysis oven and means (not shown in figure 1) of recycling the combustion gases of the boiler are provided to produce the hot gaseous fluid. This hot gaseous fluid can comprise: (i) thermolysis gases formed in the thermolysis oven 20 and previously 10 extracted from the latter by the extraction line, (ii) combustion gases of the boiler, or (iii) thermolysis gases resulting from treatment of the thermolysis gases formed in the oven 20 and previously extracted by the extraction line. For this treatment, the installation can comprise a heat exchanger 15 positioned downstream from the extraction line, into which the gases extracted from the thermolysis chamber by the extraction line are passed, as a hot fluid, a fractionation train positioned downstream from the heat exchanger into which the gases cooled by the exchanger are passed in order to obtain separate fractions containing, respectively, heavy hydrocarbons, light hydrocarbons, water and 20 gases not condensed at low temperature, a recycling line connected to the heat exchanger, downstream from the fractionation train, so as to bring a portion of the gases not condensed at low temperature into the heat exchanger, as a cold liquid, in order to raise the temperature thereof, this recycling line being connected to the supply line and passing through the boiler in order to reheat the 25 gases circulating in this recycling line by combustion of another portion of the gases not condensed at low temperature in the boiler. It will also be noted that the carriage comprises a vessel with a grille or nozzles (not visible in figure 1) opening out into the bottom of the vessel and fluidically connected by a tube or distribution system to the aforementioned 30 connection zone. The aforementioned means of fluidic connection (not shown in figure 1) comprise a telescopic device mobile between a position providing fluidic connection to the connection zone of a pipe surmounted by bellows and the 7 other end of which is connected to the supply line, and a position away from the carriage 12. The hot gaseous liquid is injected at a temperature of the order of 650 0 C into the thermolysis oven which is kept at a constant pressure of between 5 100 mbars and 1200 mbars absolute, depending on the product to be treated. Thus, the waste is first of all dehydrated, then raised to its thermolysis temperature as the carriage 12 advances in the thermolysis oven 20. After the treatment, the carriage 12 is recovered by the loader 41 at the site of the exit door 23. The bellows 24 are deployed during the transfer, in 10 order to establish a tight connection between the door 23 and the loader 41. The recovery of the carriage 12 thus takes place anew under an inert atmosphere, that is to say in the absence of free oxygen. In practice, this inert atmosphere is, during the transfer, composed of a mixture of thermolysis gases and nitrogen. 15 Here again, the loader 41 forms a screen isolating the thermolysis oven 20 from the external environment when a carriage 12 loaded with residues is extracted from it. After the transfer of the carriage 12, the doors 23 and 43 are closed again. 20 The loader 41 then conducts the carriage 12 loaded with residues to the cooling unit 30. There, the residues are emptied into a pool where they are then extracted, then graded in order to be recycled. Before this, the carriage 12 which is situated there is cooled with the help of a cold gaseous fluid, water or nitrogen. 25 The access door 31 of the cooling unit 30 is likewise a tight door of the aforementioned type, around which bellows 32 are mounted in order to establish a tight connection with the loader 41 during the transfer of a carriage between the latter and the cooling unit 30. This allows the same atmosphere to be maintained between the loader 41 and the cooling unit 30 and to prevent the 30 escape of contaminated gases into the site environment. This cooling unit is also provided with an extractor screw 33. The loader 41 can then proceed with the recovery of a fresh carriage 12 loaded with waste at the site of the door 13 of the loading unit 10.

8 Figure 2 represents an embodiment where the elements similar to those of figure 1 have been given the same reference numbers. The main differences between this installation and that of figure 1 are the result of the lay-out of the loading unit 10. The zone for presenting the 5 carriages 12 at the exit door has been replaced by two independent cells or chambers 14, 14'. Consequently, as figure 2 also shows, the routing of the carriages 12 has been substantially amended compared with figure 1, so as to be able to serve each of the cells 14, 14' with carriages 12 loaded with waste. Each of these cells 14, 14' is fitted with an entry door 15,15', 10 through which the carriage 12 loaded with waste enters, and an exit door 16, 16', at which the loader 41 recovers a carriage 12 loaded with waste. In the case of this embodiment, the vacuum and inert atmosphere can be created within these cells 14,14', in which case the cells 14, 14' will have to be fitted with tight doors of the aforementioned type and bellows in order to 15 effect a tight connection with the loader 41, if the latter is not so equipped. The structure and operation of this installation are otherwise substantially similar to those described with reference to figure 1. Figure 3 represents another variant embodiment of the installation according to the present invention, where the elements similar to those of figure 20 1 have been given the same reference numbers. The main differences between this installation and that of figure 1 are the following: The installation comprises a plurality of independent chambers 20a 20j, each forming a thermolysis oven for a single carriage 12 loaded with waste 25 and each having a tight access door 21a-21j for the passage of the carriage 12. In the case of the embodiment of figure 3, these chambers 20a-20j are grouped in order to receive two carriages. In other embodiments, the chambers can be grouped in order to receive three carriages, for example, or be independent (reception of one 30 carriage per independent chamber). In order to satisfy the cycle time in this embodiment, the chambers 20a-20j are served by two loaders 41, 41', which are fitted with two bellows 44, 9 44' identical to the bellows 22 and 24 mounted on the doors 21 and 23 of the installation of figure 1. These loaders 41, 41' recover the chariots 12 between the chambers 20b and 20i. 5 The loading unit 10 comprises two tracks 17, 18 on which carriages 12 can be positioned while awaiting loading at the hopper 11. Handling wheels, of the type mentioned above in connection with the installation of figure 1, are also visible in figure 3. Only two of them have been given a reference number, namely the number 25. 10 It goes without saying that the above description has been proposed only by way of a non-limitative example and that numerous variants can be proposed by the person skilled in the art without exceeding the scope of the invention. Thus, in particular, it is possible to use ovens comprising several 15 rows of carriages 12 loaded with waste. The chambers, such as those bearing the reference numbers 20a 20j of figure 3, can be fitted with a tight front door and rear door if it is desired, for example, to use another traffic scheme. The chambers 20i and 20j can, for example, be used to cool 20 carriages 12 loaded with residues with the help of a cold gaseous fluid, before their transfer to the unit 30 cooling by immersion of the residues in a pool. In this case, these chambers 20i and 20j are obviously no longer used for thermolysis.

Claims

1. Installation for the thermal treatment of waste, comprising: - a thermolysis oven (20; 20a-20j), substantially horizontal and intended to 5 receive at least one carriage (12) receiving waste intended to be treated by thermolysis; characterized by - transport means (40) for carriages, in order to bring each carriage loaded with waste, under an inert atmosphere, to a tight access door (21; 21a-21j) 10 at the oven and recover them, under an inert atmosphere, after thermolysis treatment, at this door (21a-21j) or at a tight exit door (23) of the oven; - means (45) of transferring each carriage (12) from the transport means (40) to the thermolysis oven (20; 20a-20j) and vice-versa; and - means (22,24; 44,44')of establishing a tight connection between the 15 transport means (40) and the thermolysis oven (20; 20a-20j) during the transfer of each carriage from the transport means (40) to the thermolysis oven (20; 20a-20j)and vice-versa.

2. Installation according to claim 1, characterized in that it comprises means (25) of conveying several carriages (12) in the thermolysis 20 oven (20; 20a-20j), between a tight entry door (21) and a tight exit door (23).

3. Installation according to claim 1 or 2, characterized in that it comprises a plurality of independent chambers (20a-20j), each forming a thermolysis oven, for a single carriage loaded with waste and each having a tight access door (21a-21j)for the passage of the carriage (12), each of these 25 chambers (20a-20j) being served by the transport means (41,41').

4. Installation according to one of claims 1 to 3, characterized in that it also comprises a cooling zone (30) for each of the carriages (12) loaded with residues, fitted with a tight access door (31) and served by the transport means (40). 30

5. Installation according to claim 4, characterized in that the cooling of the carriages (12) is effected by means of a cold gaseous fluid, nitrogen or water. 11

6. Installation according to one of claims 1 to 5, characterized in that the transport means (40) comprise at least one loader (41,41') travelling on rails (42) and defining a chamber (43), sealed tight by a door, for receiving a carriage.