Tandem batch feed and tandem batch collection apparatus for continuous pyrolysis of rubber and/or other hydrocarbon-based material

Abstract

An apparatus for vacuum pyrolysis of rubber and/or other hydrocarbon material is provided. The apparatus includes tandem batch feed hoppers operated sequentially under vacuum to continuously feed the pyrolysis reactor, and tandem batch collection bins operated in sequence under vacuum to collect the reaction product from the reactor. A process for vacuum pyrolysis is also provided.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 U.S.C. §119(e) to U.S. provisional application Serial No. 60/238,455, filed Oct. 10, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates to a continuous feed/collection apparatus for the vacuum pyrolysis of cuttings of rubber and/or hydrocarbon-based material, including hydrocarbon-contaminated soil, to yield a non-condensable fraction of combustible vapor; oil; and a carbonaceous solid residue.

BACKGROUND OF THE INVENTION

[0003] The treatment of rubber and plastics such as vehicle tires plastic and rubber residues from shredded automobiles and RDF (Refuse Derived Fuel) is a major environmental problem. Economical vacuum pyrolysis of rubber and plastics cuttings has been attempted for the past several decades. However, rubber becomes sticky and causes clogging of conventional transport systems. Some systems attempt to overcome this problem by using high temperature reactors or by recycling a portion of product residue to coat the sticky material.

[0004] U.S. Pat. No. 4,740,270 describes a process for the vacuum pyrolysis of scrap tires in which fire cuttings are moved in a multi-tray reactor with a conventional transportation system from an upper tray to a lower tray. The tire cuttings are shifted from the top tray to the bottom tray along a temperature gradient from 392° F. and peaking at 932° F. Thus, the tire cuttings are heated up while continuously moving down. Other patented processes, which utilize high temperatures, are described in U.S. Pat. Nos. 6,046,370 and 4,740,270.

[0005] U.S. Pat. No. 4,084,521 to Herbold et al. discloses a method and apparatus for pyrolysis of waste products such as tires. The apparatus includes a charging hopper that has two airtight chambers connected one after another to form an airlock. Also, a door or delivery flap is biased by counter-weight in order to crush practically all of the residual material before it can drop past a delivery flap U.S. Pat. No. 6,046,370 to Affolter et al. describes a process for vacuum pyrolysis of rubber and plastic cuttings in which a portion of the produced carbonaceous residue is added back to eliminate sticking of the hot product during processing. The process is run at a reactor temperature of 842° F. to 1022° F. Lack of commercial success of many prior art methods has led to the continued need for new methods and apparatus for vacuum pyrolysis of rubber and other hydrocarbon materials.

SUMMARY OF THE INVENTION

[0006] The present invention relates to a continuous feed/continuous collection apparatus for the treatment of rubber and/or other hydrocarbon-based material by vacuum pyrolysis of cuttings of the material to yield fractions of combustible vapor, oil, wire, and carbonaceous solid residue. The system includes a plurality of tandem feed and tandem collection bins that are designed to maintain the reaction under vacuum, while allowing a continuous flow of reactants and products to and from the reactor.

[0007] It is an object of the present invention to provide method and apparatus for vacuum pyrolysis of rubber and other hydrocarbon materials.

[0008] It is a further object of the present invention to provide an apparatus for vacuum pyrolysis of rubber and hydrocarbon materials having inlet and outlet bins maintained at vacuum pressure.

[0009] It is an additional object of the present invention to provide an apparatus for vacuum pyrolysis of rubber and hydrocarbon materials having inlet and outlet bins maintained at a vacuum that allows for continuous feed and operation while maintaining vacuum conditions.

[0010] These and other objects of the invention will become readily apparent from the following drawings, detailed description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The invention is further illustrated by the following non-limited drawings in which:

[0012] FIG. 1 schematically shows a vacuum pyrolysis apparatus having continuous feed/continuous collection apparatus according to the present invention; and

[0013] FIGS. 2(a)-(b) schematically show tandem feed and tandem collection bins according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention provides for an apparatus and process for the treatment of rubber and plastics by vacuum pyrolysis of cuttings of rubber and plastics to yield a non-condensable fraction of combustible vapor; oil; and a carbonaceous solid residue.

[0015] In one aspect of the present invention, the invention provides an apparatus for the treatment of rubber, plastics, and/or other hydrocarbon-based material comprising tandem feed bins alternating between vacuum and atmospheric pressure to load the reactor in a continuous fashion. Likewise, the apparatus may also utilize tandem collection bins alternating between vacuum and atmospheric pressure to collect the product in a continuous fashion.

[0016] In an additional aspect of the invention, the present invention provides an apparatus for reclamation and recovery of constituents of discarded vehicle tires and other rubber-based materials, including organic and inorganic materials, for reuse or environmentally-safe disposal. This apparatus comprises a feed system for transferring rubber-based material to an inlet of a low temperature reactor chamber having activation, decomposition, and completion zones, and having a helicoid auger for transferring pieces of the rubber or hydrocarbon-based material from the reactor inlet and solid product from a reactor outlet. The inlet and outlet bins are positioned at each end of the low temperature reactor chamber. The apparatus further comprises a solid material recovery system, and a vapor recovery system for recovering vapor from the decomposition zone of reactor chamber.

[0017] The vapor recovery system comprises a heat exchanger for condensing vapor from the low temperature reactor chamber, a liquid/vapor separator for separating liquids condensed in the heat exchanger, and a vacuum pump for removing vapor from the decomposition zone of the reactor chamber.

[0018] A catalyst may be used to provide a non-sticking product and allows a helical auger reactor to be used to transport the reactants. At least a portion of the carbonaceous solid residue may be mechanically mixed with the rubber and plastic cuttings before and during pyrolysis. The mechanical mixing facilitates achieving 1) a homogeneous solid mass; (2) a high transfer of heat from a reactor shell into the solid product; and (3) a reduction of the reaction time.

[0019] As shown in FIG. 2(a), the reactor is fed under vacuum in a continuous manner from one hopper while a second hopper is filled at atmospheric pressure. Just before the first hopper is empty, the second hopper is sealed and put under vacuum. The full, second hopper is then put into operation as the first hopper is opened and filled. This tandem fill and vacuum operation allows the reactor to be fed in a continuous manner. At the reactor output, a similar system is set up to empty the reactor in a continuous manner as shown in FIG. 2(b).

[0020] In a preferred embodiment, pre-dried rubber enters feeder bins and a catalytic compound is added to intensify the rubber liquefaction process. The rubber is transferred, by helicoid augers, from the feeder bins through a controlled temperature reactor chamber and into output bins. The reactor chamber is maintained under moderate vacuum and is heated to maintain temperatures which are varied spatially over the length of the reactor chamber, varying between ambient temperature and a temperature required for the process. A primary economic benefit is that the spatially-varying temperature profile reactor is designed to take advantage of the exothermic properties of the pyrolysis reaction to improve the efficiency of the process.

[0021] A feeder and recovery system removes the vapor from the reactor chamber while maintaining the system operation under vacuum. The vapor passes through a heat exchanger and separator where the liquid hydrocarbon product is removed and stored. The vapor is compressed and stored or recycled to augment the fuel used to heat the reactor. The solid residue is separated by an electromagnetic process into carbon black/carbonaceous residue and wire. The carbon is further processed through granulating equipment.

[0022] An example of a continuous feed system is shown in FIG. 1. Shredded rubber 30 or other hydrocarbon material and a catalyst 35 are moved into inlet bins or feed hoppers 40 by means of a conveyor belt 45 or other loading apparatus. The elongated reaction chamber 50 is heated at both ends by gas burner 55 and gas burner 60. The hydrocarbon material is heated in the activation zone 65, and then moves by means of a helicoid auger 70 to the decomposition zone 73, where the exothermic portion of the reaction occurs. As the reaction slows, the hydrocarbon material is moved by means of the auger to the completion zone 75, after which solid residue moves into the outlet bins 80 to a solid material recovery system 85 to yield carbon black and steel, if initially present. Vapors 90 are continuously drawn off and condensed into oil 95 by a heat exchanger or oil condensers 100 or burned as fuel during the reaction. A vacuum pump 105 draws off the vapors and maintains a vacuum during the course of the reaction.

[0023] In yet another aspect of the present invention, the invention provides a process for treating rubber and/or hydrocarbon-based material by vacuum pyrolysis. The process comprises transferring rubber and/or hydrocarbon-based material to the inlet of a low-temperature reactor chamber by a plurality of hoppers operated sequentially in vacuum and at atmospheric pressure. The rubber and/or hydrocarbon-based material is then vacuum pyrolyzed, thereby yielding a carbon black/carbonaceous solid residue, a liquid hydrocarbon product, wire, and a non-condensable combustible vapor. The rubber and/or hydrocarbon-based material can be fragmented to approximately 10×10 inch or smaller cuttings; previous separation of cords and steel threads is not required. The reactor is heated to control the pyrolysis temperature, and spatial control of the desired reaction temperature is maintained throughout the activation, decomposition and completion zones of the reactor chamber.

[0024] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

Claims

1. A continuous feed/continuous collection apparatus for pyrolysis of rubber and/or hydrocarbon-based material, comprising:

a feed system for transferring rubber and/or hydrocarbon-based material cuttings to an inlet of a low temperature reactor chamber, wherein said feed system comprises a plurality of hoppers operated in sequence, each hopper having a vacuum-sealable slide valve adjacent a top and a bottom of the hopper.

2. A continuous feed/continuous collection apparatus according to claim 1, further comprising a continuous transport system within the reactor chamber that moves a reaction product through spatially varying temperature zones.

3. A continuous feed/continuous collection apparatus according to claim 1, further comprising a collection system for collecting a solid reaction product from a reactor chamber outlet.

4. An apparatus for reclamation and recovery of constituents of discarded vehicle tires and other rubber-based materials including organic and inorganic materials for reuse or environmentally-safe disposal, comprising:

a feed system for transferring rubber-based material to an inlet of a low temperature reactor chamber, said low temperature reactor chamber having activation, decomposition, and completion zones and having a helicoid auger for transferring pieces of the rubber-based material from the reactor inlet and solid product from a reactor outlet;

inlet and outlet bins positioned at each end of the low temperature reactor chamber;

a solid material recovery system; and

a vapor recovery system for recovering vapor from the decomposition zone of said low temperature reactor chamber.

5. An apparatus according to claim 4, wherein said vapor recovery system comprises:

a heat exchanger for condensing vapor from said low temperature reactor chamber;

a liquid/vapor separator for separating liquids condensed in said heat exchanger; and

a vacuum pump for removing vapor from the decomposition zone of said low temperature reactor chamber through said heat exchanger and said liquid/vapor separator and maintaining a vacuum in said low temperature reactor chamber.

6. A continuous feed/continuous collection apparatus according to claim 2, wherein said continuous transport system comprises a helicoid auger.

7. A process for treating rubber and/or hydrocarbon-based material by vacuum pyrolysis, comprising:

transferring rubber and/or hydrocarbon-based material to an inlet of a low-temperature reactor chamber by a plurality of hoppers operated sequentially in vacuum and at atmospheric pressure;

vacuum pyrolyzing the rubber and/or hydrocarbon-based material, thereby yielding a carbon black/carbonaceous solid residue, a liquid hydrocarbon product, wire, and a non-condensable combustible vapor.

8. A process according to claim 7, further comprising fragmenting the rubber and/or hydrocarbon-based material to approximately 10×10 inch or smaller cuttings.

9. A process according to claim 7, further comprising fragmenting the rubber and/or hydrocarbon-based material without previous separation of cords and steel threads.

10. A process according to claim 7, further comprising heating the reactor to control a pyrolysis temperature.

11. A process according to claim 10, further comprising maintaining the pyrolysis temperature through controlled spatially heating of the reactor to maintain a reaction temperature.

12. A process according to claim 7, wherein the rubber or hydrocarbon-based material comprises discarded vehicle tires.