WO1998014531A1

WO1998014531A1 - Scrap pyrolysis system and reactor

Info

Publication number: WO1998014531A1
Application number: PCT/CA1997/000712
Authority: WO
Inventors: Martin C. Joynes
Original assignee: Carbonium Corporation
Priority date: 1996-10-03
Filing date: 1997-10-02
Publication date: 1998-04-09
Also published as: AU4374197A

Abstract

A pyrolysis system (10) has carriers (28, 32-44, 50) that convey scrap (70) along a track (20, 22, 24) from an intake chamber (12) through an evacuated pyrolysis chamber (14) to a discharge chamber (16). The intake chamber (12) has a port (26) for receiving a carrier (28) and another port (30) for transferring the received carrier (28) to the pyrolysis chamber (14). Multiple carrier (32-44) accumulate in the pyrolysis chamber (14) and move in succession toward the discharge chamber (16). Conduits (58, 60) extending through the pyrolysis chamber (14) are heated with combustible gas flows to produce radiant heat. Reflectors (66, 68) are located on opposing sides of the internal zone (76) containing the conduits (58, 60) and carriers (32-44) to focus radiant onto the scrap (70). The discharge chamber (16) has a port (46) for receiving a carrier (50) from the pyrolysis chamber (14) and another port (48) for removing the received carrier (50). The ports (26, 48) isolate the intake and discharge chambers (12, 16) from the ambient environment when a carrier is transferred to or from the pyrolysis chamber (14) and the chambers (12, 16) are evacuated before such transfers. The intake and discharge chambers (12, 16) are vented to the atmosphere before receiving or discharging a carrier.

Description

Description Scrap Pyrolysis System and Reactor Technical Field

The invention relates generally to pyrolysis of scrap, and has particular application, though not exclusive, to recycling of automotive tires.

Background Art Recycling tires by pyrolysis is well known. Tires are usually shredded, placed in a pyrolysis chamber, and decomposed with heat, producing solid, liquid and gaseous components. The pyrolysis chamber may be supplied with nitrogen or other gases at high pressure to maintain an inert reaction environment, but the pyrolysis chamber is preferably evacuated to enhance extraction of the various components. Gases are exhausted from the pyrolysis chamber, and liquids are accumulated, drained and processed to recover oils.

The solid component is a char from which components such as steel, wire or glass fiber can be removed. The char can then be ground or shattered into particulate carbon black. Examples of earlier pyrolysis processes and chambers are found in U.S. patent no. 5,395,404 to Burckhalter; U.S. patent no.

5,387,321 to Holland; U.S. patent no. 5,369,215 to Platz; U.S. patent no.

5,342,421 to Breu; U.S. patent no. 5,330,623 to Holland; U.S. patent no.

5,258,101 to Breu; U.S. patent no. 5,250,131 to Gitelman; U.S. patent no.

5,229,099 to Roy; U.S. patent no. 5,225,044 to Breu; U.S. patent no. 5,208,401 to Roy; U.S. patent no. 5,167,772 to Parker, Sr.; U.S. patent no.

5,099,086 to Roy; U.S. patent no. 5,087,436 to Roy; U.S. patent no.

5,084,141 to Holland; U.S. patent no. 5,084,140 to Holland; U.S. patent no.

5,057,189 to Apffel; U.S. patent no. 5,037,628 to Fader; U.S. patent no.

4,983,278 to Cha et al; U.S. patent no. 4,900,401 to Horton; U.S. patent no. 4,839,151 to Apffel; U.S. patent no. 4,839,082 to Marangoni; U.S. patent no. 4,787,321 to Schnellbacker et al; U.S. patent no. 4,740,270 to Roy;

U.S. patent no. 4,686,008 to Gibson; U.S. patent no. 4,648,328 to Keough;

U.S. patent no. 4,647,443 to Apffel; U.S. patent no. 4,588,477 to Habib;

U.S. patent no. 4,507,174 to Kutrieb; U.S. patent no. 4.472,245 to Halm; U.S. patent no. 4,401,513 to Brewer; U.S. patent no. 4,387,652 to Cooke et al; U.S. patent no. 4,308,103 to Rotter; U.S. patent no. 4,284,616 to

Solbakken et al; U.S. patent no. 4,250,158 to Solbakken et al; U.S. patent no. 4,240,587 to Letsch ; U.S. patent no. 4,203,804 to Janning et al; U.S. patent no. 4,123,332 to Rotter; U.S. patent no. 4,084,521 to Herbold et al; U.S. patent no. 4,038,100 to Haberman; U.S. patent no. 4,002,587 to Watanabe et al; U.S. patent no. 3,880,807 to Wakefield et al.

One problem associated with prior practices relates to heating of tire scrap. Scrap has been heated indirectly by contact with heated objects or with reactor walls or surfaces exposed to a heat source isolated from the environment within the reactor. Evacuation of the pyrolysis chamber, however, impairs conduction of heat, and radiant microwave or infrared sources have been proposed. Gas-powered radiant sources can generate considerable heat, potentially increasing throughput, but such sources have been inefficient and have seen little practical use. Another consideration is whether tire scrap should be pyrolized in batches or subjected to continuous processing. Reactors have been constructed to process tire scrap in distinct batches. Such a reactor is opened to receive a batch of scrap, and, once closed, a heated and evacuated environment is established and maintained until pyrolysis is complete. The reactor is then opened and allowed to cool sufficiently to permit removal of the pyrolyzed batch and introduction of a fresh batch. There are several advantages to such a reactor and batch process. Sealing the reactor from the environment is relatively simple. Preliminary shredding is not critical, and even whole tires can be pyrolyzed, as suggested, for example, in U.S. Patent No. 5,395,404 to Burkhalter. However, such processes are not energy efficient as an operative environment must be repeatedly re-established. The need to stop pyrolysis to load and unload the reactor also leads to lengthy cycle times and low throughput.

Many processes for continuous pyrolysis of tire scrap have been proposed. U.S. patent no. 4,686,008 to Gibson, for example, suggests a process in which shredded tire scrap is subjected to pyrolysis while conveyed through a heated screw drive. U.S. patent no. 5,330,623 to Holland, for example, proposes a pyrolysis process in which shredded tire scrap is spread onto belt-type conveyors and conveyed through a preliminary heating chamber and then a microwave pyrolysis chamber with upstream and downstream purge locks limiting entry of ambient air. Proposals have been made for continuous pyrolysis of whole tires, including dropping tires through a rotary feed mechanism into a fluidized pyrolysis bed and removing solid products through a drainage chute equipped with flow valves; dropping tires through gates and chutes onto belt-type conveyors for conveyance through preliminary and final pyrolysis chambers; and ramming tires through a pyrolysis chamber: U.S. patent No. 4,203,804 to Janning et al; U.S. patent no. 5,167,772 to Parker, Sr.; U.S. patent no. 5,057,189 to Apffel. Such prior art proposals appear potentially subject to inadequate sealing of the reaction chamber and unreliable pyrolysis. As regards processing of entire tires, it is not apparent that jamming can be avoided.

Disclosure Of The Invention In one aspect, the invention provides a scrap pyrolysis system comprising an intake chamber, a pyrolysis chamber, a discharge chamber, and a separate scrap carriers. The intake chamber comprises a port for introduction of a carrier and another port for coupling the intake chamber to the pyrolysis chamber. The discharge chamber comprising a port for removal of a carrier and another port for coupling the discharge chamber to the pyrolysis chamber. Each port of the intake and discharge chambers has an open state permitting passage of a carrier and a closed state preventing gas flow through the port, and each of the ports comprises controllable means for placing the port selectively in its open and closed states. Controllable conveying means convey the carriers in succession along a path from the intake chamber through the pyrolysis chamber into the discharge chamber, that path extending through the ports used to couple the intake and discharge chambers to the pyrolysis chamber.

In another aspect, the invention provides a method of scrap pyrolysis which involves repetition of a batch process. The batch process comprises introducing a carrier containing a batch of scrap into an intake chamber. After the carrier is introduced, the intake chamber is isolated from the ambient atmosphere and preferably evacuated of air, and then coupled to a pyrolysis chamber. The carrier is then conveyed from the intake chamber into the pyrolysis chamber, and the intake chamber is thereafter isolated from the pyrolysis chamber. The discharge chamber is coupled to the pyrolysis chamber for passage of the carrier, preferably evacuating air from the pyrolysis chamber before the coupling, and the carrier is then conveyed into the discharge chamber. The discharge chamber is then isolated from the pyrolysis chamber, and the carrier removed from the discharge chamber, preferably venting the discharge chamber through a valve to the ambient atmosphere before removing the carrier. The discharge chamber is thereafter isolated from the ambient atmosphere. Each repetition of the batch process may be timed to overlap immediately preceding repetitions so that several carriers accumulate in the pyrolysis chamber. The carriers may be conveyed in the pyrolysis chamber toward the discharge chamber so as to arrive at the discharge chamber according to their order of introduction into the pyrolysis chamber. Overlapping repetitions increases throughput. The system and method of the invention provide several technical advantages. Most significantly, scrap can be continually processed in distinct batches with no need to completely reestablish the working environment within the pyrolysis chamber as each batch is introduced and removed. The duration of pyrolysis can be better controlled, ensuring more complete pyrolysis. As regards scrap tires, the invention permits whole tires to be processed. This eliminates the need for shredding and consequently simplifies separation of metal and other debris from resulting tire char. Tires can, however, be cut to whatever degree desired to reduce their volume and increase the weight of individual batches. In either case, jamming is minimized since tire scrap is not loosely dropped or tumbled through gates and onto conveyors.

The method and system can be operated with any type of pyrolysis chamber. However, the pyrolysis chamber preferably comprises a gas-powered radiant heat source, particularly if scrap is to be pyrolized in near vacuum conditions. References to "radiant heat" in this patent specification should be understood as heat conveyed in the form of light, such as infrared light commonly used for heating purposes. The reactor may comprise an outer casing defining a chamber within which there is a predetermined zone in which scrap is pyrolized, burner means for igniting combustible gas to produce a hot gas flow, and one or more conduits extending through the predetermined zone. The conduits are coupled to the burner means to receive the gas flow and emit radiant heat in response to the hot gas flow. Reflector means are provided to reflect radiant heat toward the predetermined zone, the reflector means being located within the chamber between the outer casing and the internal region, essentially defining an outer boundary or boundaries of the zone in which pyrolysis actually occurs. The technical advantage is to permit efficient use of gas-powered radiant sources in pyrolysis reactors which operate at subatmospheric pressures.

Various aspects of the invention will be apparent from a description below of preferred embodiments and will be more specifically defined in the appended claims. Brief Description of the Drawings

The invention will be better understood with reference to drawings in which: fig. 1 is a diagrammatic vertical cross-section of a pyrolysis system; fig. 2 is a plan view of the pyrolysis system; fig. 3 is a view along lines 3-3 of fig. 2 further detailing an intake chamber associated with the system; fig. 4 is a sectional view along lines 4-4 of fig. 1 showing the interior of a pyrolysis chamber; fig. 5 is a view along lines 5-5 of fig. 3, fragmented, showing parts of a scrap carrier and a drive mechanism for propelling the carrier through the interior of the pyrolysis chamber; and, fig. 6 is a fragmented perspective view of the pyrolysis chamber. Best Mode of Carrying Out the Invention A general overview of pyrolysis system 10 adapted to process whole scrap tire will be provided with reference to figs. 1 and 2. The system 10 includes an intake chamber 12 which receives scrap tires, a pyrolysis chamber 14 in which the tires are thermally decomposed, and a discharge chamber 16 from which the pyrolized tires are removed. The tires are placed in distinct batches on wheeled carriers that roll on tracks leading from the intake chamber 12 to the discharge chamber 16. The tracks includes a track 20 located within the intake chamber 12, a track 22 within the pyrolysis chamber 14, and a track 24 within the discharge chamber 16. The intake chamber 12 has an inlet port 26 through which a single carrier 28 is introduced into the intake chamber 12 and located on the track 20. An outlet port 30 permits the intake chamber 12 to be coupled briefly to the pyrolysis chamber 14 for passage of a carrier. Several carriers 32X4 (even numbers only) accumulate in the pyrolysis chamber 14 and remain resident for a period of time sufficient to pyrolize their batches of scrap. The discharge chamber 16 has an inlet port 46 which permits the discharge chamber 16 to be coupled briefly to the pyrolysis chamber 14 to receive a carrier, and has an outlet port 48 through which a single carrier 50 within the discharge chamber 16 can be removed. Carriers are delivered to the intake chamber 12 along a supply track 52 (extensively fragmented), and carriers removed from the discharge chamber 16 are conveyed along a return track 54 (extensively fragmented).

The pyrolysis chamber 14 is shown in greater detail in figs. 4 and 6. It may have a conventional stainless steel construction adapted to withstand implosion under very low internal pressure. A pump (not illustrated) applies suction to the interior of the pyrolysis chamber 14 to reduce internal pressure to near vacuum conditions and to remove gaseous components produced by pyrolysis for further processing, all of which may be done in a conventional manner. The pyrolysis chamber 14 has burners 56 (apparent in figs. 1 and 2) which ignite natural gas to produce hot gas flows. The gas flows are directed through steel conduits aligned with the track 22 within the pyrolysis chamber 14. Four conduits 58 are located above the track 22 and four conduits 60, below, all in general alignment with the direction of the track 22, and turn-around bends 62 (apparent in fig. 6) join pairs of the conduits 58, 60. Spent gas flows are expelled through discharge ends 64 of the conduits (specifically indicated in fig. 2) and may be led through exhaust conduits (not shown) to heat recovery or other processing equipment (not shown). Liquids produced during pyrolysis are accumulated, drained and processed in a conventional manner. The pyrolysis chamber 14 is generally sealed and accessed only by the two ports 30, 46 leading to and from the intake and discharge chambers 12, 16.

Infrared reflectors 66, 68 are mounted within the pyrolysis chamber 14 as apparent in figs. 4 and 6. The reflectors 66, 68 define reflective surfaces 72, 74 on opposing sides of an elongate internal zone 76 of the chamber 14 where pyrolysis actually occurs and through which the carriers are conveyed. In fig. 4, an exemplary carrier 38 carrying whole scrap tires 70 in a single layer is shown passing through the internal zone 76. The conduits 58, 60 pass through the internal zone 76 in general alignment with the path defined by the track 22, placing the source of radiant heat close to the conveyed scrap. The reflectors 66, 68 are elongate in the direction of the path and in general alignment with the path. Since the conduits 58, 60 are positioned between the track 22 and the reflectors 66, 68, radiant heat emitted emitted away from the track 22 and the path of the scrap carriers is reflected back toward them. The reflectors 66, 68 may be stainless steel plates which are resistant to the hostile environment within the reactor. In practice, the reflectors 66, 68 may be periodically replaced or refurbished to maintain reactor efficiency.

The intake chamber 12 is further detailed in fig. 3. Its inlet port 26 consists of an opening 86 placing the intake chamber 12 in communication with the ambient environment, and a gate 88 hinged to chamber walls for movement between open and closed orientations relative to the opening 86. A pneumatic cylinder 90 is coupled with an arm 92 to the gate 88, and can be operated to swing the gate 88 selectively between its open and closed orientations. In its open state (solid outline in fig. 3), the port 26 permits passage of the carrier 28 into the intake chamber 12. In its closed state

(phantom outline in fig. 3), the gate 88 engages a seal 94 surrounding the opening 86 to prevent passage of gases. The outlet port 30 of the intake chamber 16 is substantially identical. It comprises a hinged gate 96, an opening 98 dimensioned to pass the carrier 28, and a pneumatic cylinder 100 and arm 102 which displace the gate 96. The arm 102 slides in sealed relationship through the pyrolysis chamber walls. In its open state (phantom outline in fig. 3), the outlet port 30 couples the intake chamber 12 to the pyrolysis chamber 14 for passage of the carrier 28, and in its closed state (solid outline in fig. 3), isolates the intake chamber 12 from the pyrolysis chamber 14, preventing passages of gases. An alternative to the hinged gates is to provide sliding gates suspended by wheeled carriages from overhead tracks and toggle-type mechanisms that press the gates against seals when operatively positioned over a port.

Pressure within the intake chamber 12 is controlled with several components. A pump 104 is operable to evacuate air or other gases from the intake chamber 12. This may be done before coupling the intake chamber 12 to pyrolysis chamber 14 for passage of a carrier, avoiding introduction of ambient air into the pyrolysis chamber 14. A valve 106 is installed in a conduit 108 coupling the intake and pyrolysis chambers 12, 14 and is operable to equalize pressure between the chambers 12, 14, which facilitates placing the discharge port 30 into its open state. Another valve 110 installed in vent pipe 112 is operable to vent the intake chamber 12 to the ambient atmosphere, effectively equalizing pressure between the intake chamber 12 and the ambient environment. This may be done prior to introducing a carrier with fresh scrap into the intake chamber 12, to facilitate placing the inlet port 28 in its open state. All components controlling pressure within the intake chamber 12 are of course separately controllable. The discharge chamber 16 is substantially identical to the intake chamber 12. Its inlet port 46 is constructed and operates in the same manner as the outlet port 30 of the intake chamber 12, but couples the intake chamber 12 to the pyrolysis chamber 14 to receive carriers in succession from the pyrolysis chamber 14. Its outlet port 48 has a construction similar to the inlet port 26 of the intake chamber 12, but couples the discharge chamber 16 to the ambient environment for removal of carriers. Like the intake chamber 12, the discharge chamber 16 has a valve (not illustrated) which permits venting of the chamber 16 to the atmosphere, a pump (not illustrated) for evacuating the chamber 16, and a pressure-equalizing valve (not illustrated) which can be operated to place the discharge chamber 16 in pressure communication with the pyrolysis chamber 14.

The general construction of the carrier 38 and the track 22 within the pyrolysis chamber 14 are apparent in fig. 4. The carrier 38 has a rectangular side wall 114, an open top 116, and a mesh bottom 118 permitting draining of liquids released during pyrolysis within the chamber 14. The track 22 comprises a pair of parallel, horizontal steel rails 122, 124. The carrier 38 has wheels 126, 128 extending from laterally opposing sides and fitted to the two rails 122, 124. The other carriers and other tracks 20, 24 within the intake and discharge chambers 12, 16 are similar.

How carriers are propelled along tracks and bridge gaps between tracks will be explained with reference to figs. 3 and 5 where the carrier 28 and one rail 130 of the track 20 within the intake chamber 12 are shown. The carrier 28 has identical forward, central and rear wheels 132, 134, 136 extending from one lateral side. ("Forward" should be interpreted as the direction of carrier movement through the system 10.) The rear wheel 136 apparent in fig. 5 has a circumferential V-shaped groove 138 in its periphery. The rail 130 has opposing upper and lower V-shaped, lengthwise projections 140, 142 that engage the groove 138 of the rear wheel 136. Engaging the wheels from above and below ensures proper reaction of torques arising when a forward or rear wheel of the carrier 28 is unsupported at a gap between tracks. The receiving end 144 of the rail 130 flares downward to facilitate receipt of a forward wheel, and the opposing end 146 of the rail 130 is beveled to accommodate opening of the outlet port 30, reducing overall spacing from the port 20. The opposing side of carrier 28 has three similar wheels (not shown) which are mounted to other identical rail (not shown) of the track 20.

The intake chamber 12 has a drive mechanism 148 that propels the carrier 28. The drive mechanism 148 has forward and rear gears 150, 152 which mesh with a toothed track 154 (teeth only partially illustrated) attached to the bottom 118 of the carrier 28 and extending the full length of the carrier 28. The rear gear 152 is mounted on a shaft 158 directly driven by an electric motor 160 mounted on the exterior of the intake chamber 12. The forward gear 150 is mounted on a shaft 162 coupled by a chain 164 to the other shaft 158. The two shafts 158, 162 extend to the other rail (not shown) of the track 20. There the shafts 158, 162 support forward and rear gears (not shown) that engage another toothed track (not shown) fixed along the bottom 118 of the carrier 28.

In fig. 3, an earlier carrier position 166 is shown in stippled outline on the supply track 52. During initial passage through the inlet port 26, the forward wheel 132 of the carrier 28 is unsupported at the gap 168 between the supply track 52 and the track 20 within intake chamber 12 until the receiving end 144 of the rail 130 receives the forward wheel 132. The central wheel 134 then completes its transition though the gap 168, and the carrier 28 is support momentary by both the supply track 52 and the track 20 within the intake chamber 12. When the central wheel 134 is received by the rail 130, the rear wheel 136 departs from the supply track 52, and the carrier 28 is then supported by its forward and central wheels 132, 134 from the supply track 52. The drive mechanism 148 associated with the intake chamber 12 then propels the carrier 28 to a final position (shown in solid outline in fig. 3) within the intake chamber 12.

A sensor 170 detects whether the carrier 28 is in the inlet port 26, including initial entry of the forward end of the carrier 28 and complete departure of the rear end of the carrier from the supply track 52. Another sensor 172 detects when the carrier 28 has advanced fully into the intake chamber 12 as shown in solid outline in fig. 3 and also when the carrier 28 has departed completely from the track 20 during transfer to the pyrolysis chamber 14. The sensor signals are used in a conventional manner to initiate and stop operation of the drive mechanism 148 and to control operation of the inlet and outlet ports 26, 30, to avoid interference between the carriers and the ports 26, 30. It should be understood that the other tracks 22, 24 in the reaction and discharge chambers 14, 16 are associated with similar drive mechanisms 174, 176 operated in response to comparable sensors. All sensors are mechanical switches with spring-biased deflecting arms that physically engage the carriers. Other sensors may be substituted; however, in the pyrolysis chamber 14, robust mechanical sensors are preferable because of the hostile internal environment. In the pyrolysis chamber 14, it is also desirable to ensure that the multiple carriers 32-44 are individually propelled toward the inlet port 46 of discharge chamber 16 rather than being push through by succeeding carriers. Multiple drive gears may be used, spaced according to carrier length and simultaneously driven.

In practice, a single batch of scrap tires is processed as follows. The tires are placed, without shredding, on a carrier and delivered along the supply track 52 to the intake chamber 12. The intake chamber 12 is vented to the atmosphere to ensure opening of its inlet port 26. The carrier is introduced through the open inlet port 26 into the intake chamber 12, and the inlet port 26 is then closed to isolate the intake chamber 12 from the ambient atmosphere. In preparation for transfer of the carrier to the pyrolysis chamber 14, the intake chamber 12 is evacuated and pressure between the intake and pyrolysis chambers 12, 14 is then equalized. The outlet port 30 of the intake chamber 12 is then placed in its open state to couple the intake and pyrolysis chambers 12, 14, and the carrier is then conveyed into the pyrolysis chamber 14. The outlet port 30 of the intake chamber 12 is then operated to isolate the intake chamber 12 from the pyrolysis chamber 14. Such a step is preferably taken immediately after the carrier has entered the pyrolysis chamber 12 but should be completed before the inlet port 26 is again opened to receive a carrier. The carrier is then conveyed at intervals along the pyrolysis chamber 14 toward the discharge chamber 16 until pyrolysis of its batch of tires is complete. The discharge chamber 16 is then evacuated and pressure between the discharge and pyrolysis chambers 16, 14 equalized. The inlet port 46 of the discharge chamber 16 is then opened to couple the discharge and pyrolysis chambers 16, 14, and the carrier is conveyed into the discharge chamber 16. The inlet port 46 of the discharge chamber 16 is then closed to isolate the discharge chamber 16 from the pyrolysis chamber 14. Before removing the carrier and pyrolyzed scrap, the discharge chamber 16 is vented to the atmosphere to equalize pressure with the ambient environment. The outlet port 48 of the discharge chamber 16 is then opened and the carrier is removed from the discharge chamber 16. The discharge chamber 16 is preferably isolated immediately from the ambient atmosphere by closing its outlet port 48, but should be so isolated before another carrier is conveyed from the pyrolysis chamber 14 into the discharge chamber 16.

To increase throughput, the processing of batches is overlapped. Thus, as the carrier 28 with fresh scrap is introduced into the intake chamber 12, the carrier 50 containing pyrolized scrap is introduced into the discharge chamber 16. As the carrier 28 is then introduced into the pyrolysis chamber 14, the carrier 50 is removed from the discharge chamber 16. Thus, multiple carriers accumulate in the pyrolysis chamber 14 and advance towards the discharge chamber 16 in their order of introduction into the pyrolysis chamber 14. The introduction and removal of carriers is timed so that pyrolysis of any given batch is complete by the time its carrier arrives at the inlet port 46 of the discharge chamber 16.

It will be appreciated that particular embodiments of the invention have been described and that modifications may be made therein without necessarily departing from the scope of the appended claims. Scrap can be shredded before processing although scrap tires are preferably processed whole. A major advantage to processing tires whole is that the steel and nylon beads commonly used in conventional tires tend to remain unitary and are more easily separated from the resulting char. Also, radiant heat can be distributed more evenly over the surfaces of whole tires than over shredded scrap, ensuring more even pyrolysis. In the exemplary pyrolysis chamber 14, the track 22 and carriers are adapted to convey entire tires with their general planes oriented horizontal, that is, flat against the mesh bottoms of the carriers. The reflectors 66, 68 and conduits 58, 60 are thus positioned above and below the track 22, directing light onto the larger side surfaces of the tires. Liquid products of pyrolysis thus tend to drip onto the lower reflector and to some degree vaporize and then deposit on colder reactor surfaces. To avoid dripping onto reflectors and subsequent deposition elsewhere, the carriers may be adapted to support the tires with their general planes vertical, and the reflectors 66, 68 and conduits 58, 60 may be positioned on horizontally opposing sides of the track 22. This allows liquid by-products to drop directly to the bottom of the reactor vessel where they can be immediately collected and drained. Also, the carriers carriers may then be more readily suspended from a single overhead rail rather than the pairs of horizontally spaced rails illustrated.

Claims

1. A scrap pyrolysis system (10) comprising an intake chamber (12), a pyrolysis chamber (14), and a discharge chamber (16), characterized by: a plurality of separate scrap carriers (28, 32X4, 50); the intake chamber (12) comprising a port (26) for introduction of a carrier (28) into the intake chamber (12) and another port (30) for coupling the intake chamber (12) to the pyrolysis chamber (14); the discharge chamber (16) comprising a port (48) for removal of a carrier (50) from the discharge chamber (16) and another port (46) for coupling the discharge chamber (16) to the pyrolysis chamber (14); each of the ports (26, 30, 46, 48) of each of the intake and discharge chambers (12, 16) comprising an open state permitting passage of a carrier through the port (26, 30, 46 or 48) and a closed state preventing gas flow through the port (26, 30, 46 or 48) and comprising controllable means (88, 90, 92 or 96, 100, 102) for placing the port (26, 30, 46 or 48) selectively in its open and closed states; and, controllable conveying means (20, 22, 24, 148, 174, 176) for conveying the carriers (28, 32X4, 50) in succession along a path from the intake chamber (12) through the pyrolysis chamber (14) into the discharge chamber (16), the path extending through the ports (30, 46) for coupling the intake and discharge chambers (12, 16) to the pyrolysis chamber (14).

2. The pyrolysis system ( 10) of claim 1 in which the pyrolysis chamber (14) comprises: means for maintaining a subatmospheric pressure within the pyrolysis chamber (14); burner means (56) for igniting combustible gas to produce a hot gas flow; and, conduits (58, 60) coupled to the burner means (56) to receive the hot gas flow and emitting radiant heat in response to the hot gas flow, the conduits (58, 60) extending through the interior of the pyrolysis chamber (14) proximate to the path of the carriers (28, 32X4, 50); and, reflector means (66, 68) within the pyrolysis chamber (14) for reflecting radiant heat emitted by the conduits (58, 60) toward the path of the carriers (28, 32X4, 50), the conduits (58, 60) being positioned between the reflector means (66, 68) and the path of the carriers (28, 32X4, 50).

3. The pyrolysis system ( 10) of claim 2 in which the reflector means (66, 68) comprise one reflector (66) positioned on one side of the path and another reflector (68) positioned on an opposite side of the path, each of the reflectors (66, 68) defining a reflective surface (72 or 74) facing towards path.

4. The pyrolysis system (10) of claim 1 in which each of the intake and discharge chambers (12, 16) comprises controllable exhaust means (104) for exhausting air from the chamber (12 or 16) and controllable venting means (110, 112) for introducing ambient air into the chamber (12 or 16).

5. The pyrolysis system (10) of claim 4 in which each of the intake and discharge chambers (12, 16) comprises controllable pressure equalizing means (106, 108) for placing the chamber (12 or 16) in pressure communication with the pyrolysis chamber (14).

6. The pyrolysis system (10) of claim 1 in which the conveying means (20, 22, 24, 148, 174, 176) comprise a track (20) within the intake chamber (12) extending between the ports (26, 30) of the intake chamber (12), a separate track (22) within the pyrolysis chamber (14) extending between the ports (30, 46) that couple the intake and discharge chambers (12, 16) to the pyrolysis chamber (14), and a separate track (24) within the discharge chamber (16) extending between the ports (46, 48) of the discharge chamber (16).

7. The pyrolysis system (10) of claim 6 in which each of the carriers (28, 32X4, 50) comprises wheels (126, 128, 132, 134, 136), and each of the tracks (20, 22, 24) is shaped to support the wheels (126, 128, 132, 134, 136) of the carriers (28, 32X4, 50).

8. The pyrolysis system (10) of claim 7 in which the conveying means (20, 22, 24, 148, 174, 176) comprises means (148, 174, 176) associated with each of the intake, pyrolysis and discharge chambers (12, 14. 16) for engaging and propelling a carrier along the track (20, 22 or 24) of the associated chamber (12, 14 or 16).

9. A method of pyrolizing scrap (70) in a pyrolysis chamber (14), the method comprising repetition of a batch process, the batch process being characterized by: introducing a carrier (28 or 32-44 or 50) containing a batch of scrap (70) into an intake chamber (12); isolating the intake chamber (12) from the ambient atmosphere after the introducing of the carrier (28 or 32X4 or 50) and thereafter coupling the intake chamber (12) to the pyrolysis chamber (14) for passage of the carrier (28 or 32-44 or 50) therebetween; conveying the carrier (28 or 32X4 or 50) from the intake chamber (12) into the pyrolysis chamber (14) after the coupling of the intake chamber (12) to the pyrolysis chamber (14) and thereafter subjecting the batch of scrap (70) to pyrolysis within the pyrolysis chamber (14); isolating the intake chamber (12) from the pyrolysis chamber (14) after the conveying of the carrier (28 or 32-44 or 50) into the pyrolysis chamber (14); coupling the discharge chamber ( 16) to the pyrolysis chamber

(14) for passage therebetween of the carrier (28 or 32X4 or 50); conveying the carrier (28 or 32-44 or 50) from the pyrolysis chamber (14) into the discharge chamber (16) after the coupling of the discharge chamber (16) to the pyrolysis chamber (14); isolating the discharge chamber (16) from the pyrolysis chamber

(14) after the conveying of the carrier (28 or 32X4 or 50) into the discharge chamber (16); and, removing the carrier (28 or 32X4 or 50) from the discharge chamber (16) and thereafter isolating the discharge chamber (16) from the ambient atmosphere.

10. The method of claim 9 in which: each repetition of the batch process is overlapped with immediately preceding repetitions of the batch process such that a plurality of carriers (32X4) containing batches of scrap (70) accumulate in the pyrolysis chamber ( 14) ; and, the batch process comprises conveying each of the carriers (32X4) during pyrolysis in the pyrolysis chamber (14) toward the discharge chamber (16) such that the accumulated carriers (32X4) arrive at the discharge chamber (16) in succession according to their order of introduction into the pyrolysis chamber (14).

1 1. The method of claim 10 in which the batch process comprises: evacuating air from the intake chamber (12) after the isolating of the intake chamber (12) from the ambient environment and before the coupling of the intake chamber (12) to the pyrolysis chamber (14); and, evacuating air from the discharge chamber ( 16) immediately before the coupling of the discharge chamber (16) to the pyrolysis chamber (14).

12. The method of claim 11 in which the batch process comprises: venting the intake chamber (12) through a valve to the ambient atmosphere before the introducing of the carrier (28 or 32X4 or 50); and, venting the discharge chamber (16) through a valve to the ambient atmosphere after the isolating of the discharge chamber (16) from the pyrolysis chamber (14) and before the removing of the carrier (28 or 32X4 or 50) from the discharge chamber (16).

13. The method of claim 11 in which the batch process comprises: opening a valve between the intake chamber (12) and the pyrolysis chamber (14) thereby to equalize pressure between the intake chamber (12) and the pyrolysis chamber (14) after the evacuating of the intake chamber (12) and before the coupling of the intake chamber (12) to the pyrolysis chamber (14) for passage of the carrier (28 or 32X4 or 50) therebetween; and, opening a valve between the discharge chamber (16) and the pyrolysis chamber (14), thereby to equalize pressure between the discharge chamber (16) and the pyrolysis chamber (14), after the evacuating of the discharge chamber (16) and before the coupling of the discharge chamber (16) to the pyrolysis chamber (14) for passage of the carrier (28 or 32X4 or 50) there between.

14. The method of claim 9, 10, 11, 12 or 13 in which: the scrap (70) is tires; and, the pyrolysis chamber (14) is maintained at a subatmospheric pressure.

15. A scrap pyrolysis reactor comprising a casing (78) defining a chamber (14) which has a predetermined zone (76) in which scrap (70) is subjected to pyrolysis, means for maintaining a subatmospheric pressure within the chamber (14) during pyrolysis, burner means (56) for igniting combustible gas to produce a hot gas flow, and one or more conduits (58, 60) extending through the predetermined zone (76) and coupled to the burner means (56) to receive the gas flow and emitting radiant heat in response to the hot gas flow, characterized by reflector means (66, 68) for reflecting radiant heat emitted by the conduits (58, 60) toward the predetermined zone (76), the reflector means (66, 68) being located within the chamber (14) between the casing (78) and the predetermined zone (76).

16. The scrap pyrolysis reactor of claim 15 in which the reflector means (66, 68) comprise a reflector (66) positioned on one side of the predetermined zone (76) and another reflector (68) positioned on an opposite side of the predetermined zone (76), each of the reflectors (66, 68) defining a reflective surface (72 or 74) facing toward the predetermined zone (76).