OPTIMIZED THERMOLYSIS INSTALLATION AND METHOD FOR IMPLEMENTING SAME

Abstract

A waste thermolysis installation includes a first, drying, enclosure able to vacuum dry the incoming waste and a second, calcining, enclosure, able to perform a vacuum calcination treatment on the dried waste coming from the first enclosure, each enclosure including an external-heating system including a combustion chamber and a vacuum pump which makes it possible to maintain the vacuum in the enclosure and is connected to the enclosure by an extraction pipe, the installation being characterized in that it includes a pipe circulating gas coming from the second enclosure to the second enclosure through the system for the external heating of the second enclosure. Thermolysis method implementing the installation.

Claims

1. An installation (22) for thermolysis of waste comprising at least two vessels (2,4), that is to say a drying first vessel (2) and a calcining second vessel (4), each of these two vessels (2,4) being able to operate under a vacuum, the first vessel (2) being able to dry the incoming waste and the second vessel (4) being able to perform calcination treatment of the dried waste from the first vessel (2), each of the two vessels (2,4), for drying and calcining, comprising a system for external heating having at least one combustion chamber (3,5), and at least one vacuum pump (15,16) making it possible to maintain the vacuum in said vessel (2,4) and which is linked to said vessel (2,4) by an extraction pipe, Said installation (22) being characterized in that it comprises at least one pipe (14,12) for circulating gas from the second vessel (4) to the second vessel (4) through the system for external heating (5) of the second vessel (4).

2. The thermolysis installation (22) according to claim 1, further comprising at least one pipe (14, 30, 29, 11) for circulating gas from the second vessel (4) to the first vessel (2), preferably through the system for external heating (3) of the first vessel (2).

3. The thermolysis installation (22) according to claim 2, wherein the pipe (14,30,29,11) for circulating gas from the second vessel (4) to the first vessel (2) passes through the combustion chamber (3) of the first vessel (2).

4. The thermolysis installation (22) according to claim 1, wherein the pipe (14, 12) for circulating gas from the second vessel (4) to the second vessel (4) passes through the combustion chamber (5) of the second vessel (4).

5. The thermolysis installation (22) according to claim 4, further comprising at least one pipe (13, 11) for circulating gas from the first vessel (2) to the first vessel (2), which pipe (13, 11) preferably passes through the combustion chamber (3) of the first vessel (2).

6. The installation (22) according to claim 1, further comprising at least one supply pipe (27, 28) of at least one of the two combustion chambers (3, 5) by at least one diverting pipe (30, 31, 26) connected to the pipe (14,12) for circulating gas from the second vessel (4) to the second vessel (4).

7. The installation (22) according to claim 1, further comprising at least one communication pipe (25) between the combustion chamber (3) of the first vessel (2) and the combustion chamber (5) of the second vessel (4).

8. The thermolysis installation (22) according to claim 1, further comprising a third vessel (6) for cooling, able to operate under a vacuum and able to cool the solid residues from the second vessel (4).

9. The installation (22) according to claim 8, further comprising a lock (1) for introduction of incoming waste into the first vessel (2) and/or a lock (7) for exit of the cooled solid residues from the third vessel (6), each of the locks (1, 7) being connected to at least one vacuum pump (24).

10. A thermolysis method for implementing the installation (22) according to claim 1, said installation (22) comprising at least two successive vessels (2,4), that is to say a drying first vessel (2) and a calcining second vessel (4), each of the two vessels (2,4), for drying and calcining, comprising a system for external heating comprising at least one combustion chamber (3,5), and at least one vacuum pump (15,16) making it possible to maintain the vacuum in said vessel by extraction of gas from the vessel (2,4), Said process being such that incoming waste is introduced into the drying first vessel (2) operating under a vacuum and dried waste from the first vessel (2) is introduced into the calcining second vessel (4) operating under a vacuum, Said process being characterized in that it comprises at least one instance (14,12) of recycling gas from the second vessel (4) to the second vessel (4) after heating through the system (5) for external heating of the second vessel (4), preferably carried out by passage within the combustion chamber (5) of said second vessel (4).

11. The thermolysis method according to claim 10, wherein gas from the second vessel (4) is recycled (30, 29, 11) to the first vessel (2), possibly after heating through the system for external heating (3) of said first vessel (2).

12. The thermolysis method according to claim 10, such that said heating through the system (5) for external heating of the second vessel (4) is carried out by passage within the combustion chamber (5) of said second vessel (4).

13. The thermolysis method according to claim 10, wherein at least one of the two combustion chambers (3, 5) of the first vessel (2) and of the second vessel (4) is supplied (27, 28) by at least part of the gases from the first vessel (2) and/or from the second vessels (4).

14. The thermolysis method according to claim 13, wherein said part of the gases are pre-treated before supplying the combustion chamber or chambers (3,5).

15. The thermolysis method according to claim 10, wherein the solid residues from the second vessel (4) are cooled in a cooling third vessel (6) operating in a vacuum.

16. The thermolysis installation (22) according to claim 2, wherein the pipe (14, 12) for circulating gas from the second vessel (4) to the second vessel (4) passes through the combustion chamber (5) of the second vessel (4).

17. The installation (22) according to claim 2, further comprising at least one supply pipe (27, 28) of at least one of the two combustion chambers (3, 5) by at least one diverting pipe (30, 31, 26) connected to the pipe (14,12) for circulating gas from the second vessel (4) to the second vessel (4).

18. The installation (22) according to claim 3, further comprising at least one supply pipe (27, 28) of at least one of the two combustion chambers (3, 5) by at least one diverting pipe (30, 31, 26) connected to the pipe (14,12) for circulating gas from the second vessel (4) to the second vessel (4).

19. The installation (22) according to claim 4, further comprising at least one supply pipe (27, 28) of at least one of the two combustion chambers (3, 5) by at least one diverting pipe (30, 31, 26) connected to the pipe (14,12) for circulating gas from the second vessel (4) to the second vessel (4).

20. The installation (22) according to claim 5, further comprising at least one supply pipe (27, 28) of at least one of the two combustion chambers (3, 5) by at least one diverting pipe (30, 31, 26) connected to the pipe (14,12) for circulating gas from the second vessel (4) to the second vessel (4).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The disclosure of the invention will now be continued with the detailed description of an embodiment, given below by way of non-limiting example, with reference to the accompanying drawing. In this:

[0057] FIG. 1 is a diagrammatic cross-section view of a thermolysis installation according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] FIG. 1 illustrates an installation 22 for waste thermolysis comprising a drying first vessel 2 and a calcining second vessel 4. In this FIGURE, the directions of circulation of the fluids are indicated by arrows. Unless expressly indicated otherwise, the fact that two pipes meet in FIG. 1 means that those pipes are connected.

[0059] The first vessel 2 is able to operate under a vacuum and is able to dry the incoming waste, for its subsequent treatment by thermolysis in the calcining vessel 4. It comprises a system for external heating consisting of a combustion chamber 3, comprising a burner 9, and a vacuum pump 15 making it possible to maintain the vacuum in said vessel 2 and which is connected to said vessel 2 by an extraction pipe 13. This combustion chamber 3 comprises a wall forming a double shell surrounding the vessel 2. According to the invention, the installation 22 comprises a pipe for circulating (13; 29; 11) consisting of the extraction pipe 13 enabling the passage by the vacuum pump 15, said pipe 13 communicating with a pipe 18 enabling evacuation of the gases, a pipe 29, and a pipe 11 for circulating gas to the first vessel 2. The pipe 11 passes through the heating system of said first vessel 2, that is to say through the combustion chamber 3. The pipe 11 at that location is of coil form which is configured to increase the time of presence of the gas in the pipe 11 within the combustion chamber 3. The gases that are not recycled in the first vessel 2 may be evacuated by the evacuation pipe 18.

[0060] The second vessel 4 is able to operate under a vacuum and is able to perform calcination treatment of the dried waste from the first vessel 2. It comprises a system for external heating consisting of a combustion chamber 5, comprising a burner 10, and a vacuum pump 16 making it possible to maintain the vacuum in said vessel 4 and which is connected to said vessel 4 by an extraction pipe 14. This combustion chamber 5 comprises a wall forming a double shell surrounding the vessel 4. According to the invention, the installation 22 comprises a pipe for circulating (14,12) consisting of the extraction pipe 14 enabling the passage by the vacuum pump 16, said pipe 14 dividing into a pipe 30, and a pipe 12 for circulating gas to the second vessel 4. The pipe 12 passes through the heating system of said second vessel 4, that is to say through the combustion chamber 5. The pipe 12 at that location is of coil form which is configured to increase the time of presence of the gas in the pipe 12 within the combustion chamber 5. The gases that are not recycled in the second vessel 4 may be evacuated by a pipe 19 enabling evacuating of the gases, the pipe 19 being connected to the pipe 14 by the pipe 30 then a pipe 31.

[0061] According to a variant represented in FIG. 1, the pipe 31 divides into pipe 19 and a pipe 26. The pipe 26 divides into the pipes 27 and 28 (which is not connected to pipes 11 and 13), respectively making it possible to provide part of the evacuated gases to the respective burners 9 and 10 of the respective combustion chambers 3 and 5. These gases typically undergo pre-treatment (not shown), among which is condensation and elimination of water, before supplying the burners 9 and 10. At the time of the operation of the installation 22, it is possible that just one of the burners 9 and 10 is supplied by at least some of the gas from the second vessel 4.

[0062] According to a variant not shown, it is also possible to provide a supply line to at least one of the burners 9 and 10 from an evacuation pipe 18 linked to the first vessel.

[0063] According to another variant, not shown, it is possible for the combustion chamber 3 not to comprise a burner 9, the combustion chamber 3 being solely heated by the provision of gas from the second vessel 4.

[0064] According to the invention, the installation 22 further comprises a pipe (14, 30, 29, 11) for circulating gas from the second vessel 4 to the first vessel 2 through the heating system, that is to say the combustion chamber 3, of said first vessel 2. This pipe for circulating is formed by the pipe 14, by the pipe 30 (which divides into the pipe 31 and a pipe 29), by the pipe 29 and by the pipe 11.

[0065] It is arranged for the combustion smoke from the combustion chambers 3 and 5 to be evacuated by a chimney 8. According to a variant represented in FIG. 1, the combustion chambers 3 and 5 are linked by a communication pipe 25.

[0066] The installation 22 further comprises a third vessel 6 for cooling by scrubbing with water, able to operate under a vacuum and able to cool the solid residues from the second vessel 4.

[0067] The cooling vessel 6 is supplied by a cooling circuit 21, able to use water, which comes out from a multiplicity of jets in the vessel 6. The vacuum is maintained in the vessel 6 by a vacuum pump 17, which is able to evacuate the gases thus extracted by an evacuation pipe 20. The water vapor is condensed and evacuated by an evacuation pipe (not shown).

[0068] The installation 22 further comprises an entry lock 1, consisting of two sub-parts 1a and 1b and three valves 101, 102 and 103. The combination of movements of the valves 101, 102 and 103 enables the lock 1 to operate. In a first phase, the incoming waste (not shown) is introduced from the exterior of the installation 22 into a first sub-part 1a of the lock 1, under atmospheric pressure, by the opening of the valve 101, while the other sub-part 1b of the lock 1 is isolated from the exterior by the closing of the valve 103. The valve 102 is closed, insolating the vessel 2 from the lock 1. In a second phase, the valve 101 is closed and the waste is transferred into the second sub-part 1b of the lock 1, under reduced pressure, by opening the valve 103. Lastly, in a third phase, the opening of the valve 102 enables the entry of the waste into the vessel 2. In the case represented in FIG. 1, the valves 101 and 102 are open and the valve 103 is closed.

[0069] The installation 22 further comprises an exit lock 7, consisting of two sub-parts 7a and 7b and three valves 71, 72 and 73. The combination of movements of the valves 71, 72 and 73 enables the lock 7 to operate. In a first phase, the cooled solid residues (not shown) are taken out from the vessel 6 to a first sub-part 7a of the lock 7, under reduced pressure, by the opening of the valve 72, while the other sub-part 7b of the lock 7 is isolated from the vessel 6 by the closing of the valve 73. The valve 71 is closed, isolating the lock 7 from the exterior. In a second phase, the valve 72 is closed and the solid residues are transferred into the second sub-part 7b of the lock 7, under atmospheric pressure, by opening the valve 73. Lastly, in a third phase, the opening of the valve 71 enables the exit of the residues to the exterior of the installation 22. In the case represented in FIG. 1, the valves 71 and 72 are open and the valve 73 is closed.

[0070] A vacuum line 23 may be formed by a vacuum pump 24, linking the locks 1 and 7. The gases extracted for maintaining the vacuum are extracted by the vacuum pump 24.

[0071] The full or partial implementation of the installation 22 carries out a thermolysis method according to the invention, as used in the following two example embodiments. The installation enables implementation of different embodiments of the invention as described above. In the examples, two embodiments are used, described below. These embodiments partly use the installation 22 described above, in particular regarding the recycling of the combustible gases from the second vessel 4, and possibly regarding the cooling of the solid residues from the second vessel 4.

[0072] According to this thermolysis method, incoming waste is introduced, via the lock 1, into the drying first vessel 2, operating under a vacuum, then the dried waste from the first vessel 2 is introduced into the second vessel 4, operating under a vacuum. Next the solid residues from the second vessel 4 are possibly introduced into the third vessel 6, operating under a vacuum. Lastly, the cooled solid residues are possibly extracted from the vessel 6 via the lock 7.

[0073] Gas is recycled, via the pipes 14 then 12, from the second vessel 4 to the second vessel 4, through the combustion chamber 5 of the second vessel 4.

[0074] Gas may be recycled, via the pipes 13 then 11, from the first vessel 2 to the first vessel 2, through the combustion chamber 3 of the first vessel 2.

[0075] Gas may be recycled, via the pipes 14 then 30 then 29 then 11, from the second vessel 2 to the first vessel 2, through the combustion chamber 3 of the first vessel 2.

[0076] The two combustion chambers 3 and 5 of the first vessel 2 and second vessel 4 are supplied with at least part of the gases from the second vessel 4, via the pipes 26, 27 and 28.

[0077] According to a first example embodiment, three vessels 2, 4 and 6 each have an inside diameter of approximately 2 m and a length of approximately 6 m The installation 22 comprising the three vessels has a treatment capacity of approximately 10 000 tonnes per year according to the type of waste. The smoke 8 enables an electrical unit of approximately 5 MW to operate. From 5 to 15 of the combustibles serves for the actual calcination method.

[0078] The operating conditions of the method are as follows: [0079] the temperature in the drying vessel 2 is approximately 100 C.; [0080] the temperature in the calcining vessel 4 is approximately 180 to 400 C.; [0081] the temperature of the combustion smoke in the combustion chambers 3 and 5 is approximately 1200 C.; and [0082] the temperature of the combustion smoke in the chimney 8 is approximately 200 to 400 C.

[0083] In practice, 1000 kg of products to treat, according to two different cases, were introduced into the first vessel 2 and gave rise: [0084] either to 300 kg and 240 kg of solids (charcoals), 130 kg of oils and 100 kg of gases where the products to treat were household garbage; [0085] or to 30 kg and 280 kg of solids (charcoals), 380 kg of oils and 150 kg of gases where the products to treat were tires.

[0086] According to a second example embodiment, 500 kg of products to treat (household garbage), at 30% moisture content, were treated in two vessels, i.e. the drying vessel (first vessel) and the calcining vessel (second vessel). As a matter of fact, in this case, cooling is carried out in the calcining vessel after the calcining.

[0087] The heating on starting up was carried out with supplementary gas (mains gas). The gases extracted by a liquid-ring pump were kept at approximately 100 C. for as long as the products were not dry. After passage within the second vessel, the temperature of the gases rose, up to 250 C. on average, after a heating period of 45 minutes. The extracted gas was used as a combustible for the method. Approximately 70 kg of oil, 120 kg of charcoal and 100 kg of inert matter comprising metals and minerals was recovered. In the absence of oxygen, the metals were not corroded.