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Publication numberUS20080128259 A1
Publication typeApplication
Application numberUS 11/935,760
Publication date5 Jun 2008
Filing date6 Nov 2007
Priority date6 Nov 2006
Also published asCA2668886A1, EP2091672A2, US20110024280, WO2008058137A2, WO2008058137A3
Publication number11935760, 935760, US 2008/0128259 A1, US 2008/128259 A1, US 20080128259 A1, US 20080128259A1, US 2008128259 A1, US 2008128259A1, US-A1-20080128259, US-A1-2008128259, US2008/0128259A1, US2008/128259A1, US20080128259 A1, US20080128259A1, US2008128259 A1, US2008128259A1
InventorsStanislaw Kostek
Original AssigneeStanislaw Kostek
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Methods and apparatus for pyrolyzing material
US 20080128259 A1
Abstract
Methods and systems for substantially continuously treating comminuted material containing carbon and hydrogen, for example, used tires, are provided. The methods include the steps of introducing the tire material to an elongated chamber, transferring the tire material through the elongated chamber, heating the tire material to a temperature sufficient to pyrolyze the material to produce a gaseous stream; discharging the gaseous stream from the chamber, and cooling at least some of the gaseous stream to liquefy components of the stream. The transfer may be effected by a flexible, center-less screw conveyor to minimize material buildup in the vessel. The cooling of the gaseous stream may be practiced by reverse condensation. One or more re-usable fuel streams are provided by aspects of the invention.
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Claims(39)
1. A method of treating one or more feed materials containing carbon and hydrogen compounds in an elongated pyrolysis chamber having an inner surface, at least one material inlet, and at least one outlet, the method comprising:
(1) introducing the feed material into the material inlet of the pyrolysis chamber;
(2) continuously conveying the feed material through the pyrolysis chamber while substantially simultaneously removing build-up of feed material or the pyrolysis products thereof from the inner surface of the pyrolysis chamber;
(3) maintaining a temperature of the feed material and pryolysis products thereof within the pyrolysis chamber at a level sufficiently high to pryolyze the feed material to form gaseous hydrocarbons, and
(4) discharging the gaseous hydrocarbons from the at least one outlet of the pyrolysis chamber.
2. The method as recited in claim 1, wherein the one or more feed materials comprise comminuted tires.
3. The method as recited in claim 1, wherein the method further comprises extracting air from the feed material prior introducing the feed material to the pyrolysis chamber.
4. The method as recited in claim 1, wherein said continuously conveying the feed material comprises rotating a helical centerless screw within the pyrolysis chamber, the helical center-less screw having a plurality of screw flights sized to a provide clearance between the flights and the interior surface of the pyrolysis chamber.
5. The method as recited in claim 1, wherein the temperature comprises a temperature between about 450 degrees C. and about 475 degrees C.
6. The method as recited in claim 1, wherein the method further comprises discharging a least one liquid hydrocarbon.
7. The method as recited in claim 1, wherein the method further comprises discharging at least one of CO and H2.
8. The method as recited in claim 1, wherein the method further comprises cooling the material near the outlet of the elongated pyrolysis chamber.
9. The method as recited in claim 1, further comprising using at least some of the gaseous hydrocarbons produced in the practice of maintaining the temperature.
10. An apparatus for pryolyzing one or more feed materials containing carbon and hydrogen compounds, the apparatus comprising:
(1) an elongated pyrolysis chamber having an inner surface, one or more inlets for introducing the feed material, and one or more outlets;
(2) means for continuously conveying the feed material and pyrolysis products thereof through the pyrolysis chamber while substantially simultaneously removing any build-up of feed material and the pyrolysis products from the inner surface of the pyrolysis chamber;
(3) means for maintaining the temperature within the pyrolysis chamber at a level sufficiently high to pryolyze at least some of the feed material to gaseous hydrocarbons; and
(4) means for discharging the gaseous hydrocarbons through the one or more outlets.
11. The apparatus as recited in claim 10, wherein the pyrolysis chamber comprise a horizontally-positioned, cylindrical vessel having a diameter of about 12 inches to about 16 inches.
12. The apparatus as recited in claim 11, wherein the pyrolysis chamber comprises a length of about 30 feet to about 40 feet.
13. The apparatus as recited in claim 10, wherein the pyrolysis chamber comprises a plurality of elongated pyrolysis chambers.
14. The apparatus as recited in claim 10, wherein the means for continuously conveying the feed material comprises a rotating helical center-less screw mounted for rotation within the pyrolysis chamber, the helical center-less screw having a plurality of flights sized to a provide clearance between the flights and the interior surface of the pyrolysis chamber.
15. The apparatus as recited in claim 14, wherein the means for continuously conveying the feed material further comprises an initial portion comprising means for reducing a size of the feed material.
16. The apparatus as recited in claim 10, wherein the pyrolysis chamber further comprises means for cooling the pyrolysis products.
17. The apparatus as recited in claim 10, further comprising means for using at least some of the gaseous hydrocarbons produced in the practice of maintaining the temperature.
18. The apparatus as recited in claim 10, further comprising means for minimizing the introduction of air to the pyrolysis chamber.
19. The apparatus as recited in claim 18, wherein the means for minimizing the introduction of air comprises a double air lock.
20. A method for substantially continuously treating comminuted material containing carbon and hydrogen, the method comprising:
introducing the comminuted material to an elongated chamber having little or no oxygen;
transferring the comminuted material through the elongated chamber;
heating the comminuted material to a temperature sufficient to pyrolyze the comminuted material to produce gaseous hydrocarbons and at least some carbon-containing solids;
discharging the gaseous hydrocarbons from the chamber;
cooling at least some of the gaseous hydrocarbons to liquefy the hydrocarbons; and
discharging the carbon-containing solids from the chamber.
21. The method as recited in claim 20, wherein transferring comprises transferring while minimizing buildup of the comminuted material and the carbon-containing solids on an insider surface of the elongated chamber.
22. The method as recited in claim 21, wherein minimizing the buildup of material and solids comprises conveying a scraping device over the inside surface of the elongated cylinder.
23. The method as recited in claim 22, wherein conveying a scraping device comprises transferring the material with a center-less screw conveyor having at least one flight that bears against the inside surface of the elongated chamber.
24. The method as recited in claim 20, wherein cooling at least some of the gaseous hydrocarbons comprises passing the gaseous hydrocarbons in heat exchange relationship with a cooler fluid.
25. The method as recited in claim 24, wherein the gaseous hydrocarbons are discharged at a first temperature, and wherein passing the gaseous hydrocarbons in heat exchange relationship with a cooler fluid comprises passing the gaseous hydrocarbons at the first temperature in heat exchange relationship with a fluid having a second temperature lower than the first temperature to produce a first cooler stream of gaseous hydrocarbons at a third temperature lower than the first temperature.
26. The method as recited in claim 25, wherein passing the gaseous hydrocarbons in heat exchange relationship with a cooler fluid further comprises passing the gaseous hydrocarbons at the third temperature in heat exchange relationship with a fluid having a fourth temperature lower than the third temperature to produce a second cooler stream of gaseous hydrocarbons at a fifth temperature lower than the third temperature.
27. The method as recited in claim 20, wherein the comminuted material containing carbon and hydrogen comprises comminuted tires.
28. The method as recited in claim 20, wherein heating the comminuted material to a temperature sufficient to pyrolyze the comminuted material comprises heating the comminuted material to at least 400 degrees C.
29. A method from producing liquid hydrocarbons from comminuted carbon and hydrogen containing material, the method comprising:
introducing the comminuted material to a chamber having little or no oxygen;
heating the comminuted material to a temperature sufficient to produce gaseous hydrocarbons at a first temperature;
cooling the gaseous hydrocarbons to condense a first liquid hydrocarbon from the gaseous hydrocarbons and a first cooler stream of gaseous hydrocarbons at a second temperature lower than the first temperature; and
cooling the first cooler stream of gaseous hydrocarbons to a third temperature, lower than the second temperature, to condense a second liquid hydrocarbon from the first cooler stream of gaseous hydrocarbons and a second cooler stream of gaseous hydrocarbons.
30. The method as recited in claim 29, wherein the first liquid hydrocarbon has a greater density than the second liquid hydrocarbon.
31. The method as recited in claim 29, wherein the method further comprises cooling the second cooler stream of gaseous hydrocarbons to a fourth temperature, lower than the third temperature, to condense a third liquid hydrocarbon from the second cooler stream of gaseous hydrocarbons and a third cooler stream of gaseous hydrocarbons.
32. The method as recited in claim 29, wherein the comminuted material containing carbon and hydrogen comprises comminuted tires.
33. The method as recited in claim 29, wherein heating the comminuted material to a temperature comprises heating the comminuted material to at least 400 degrees C.
34. A treatment apparatus for comminuted material containing carbon and hydrogen, the apparatus comprising:
an elongated cylindrical chamber having a first end and a second end;
a centerless helical screw conveyor mounted for rotation in the elongated cylindrical chamber;
means for rotating the centerless helical screw conveyor to transfer the comminuted material from the first end to the second end; and
means for heating the cylindrical chamber to a temperature sufficient to produce gaseous hydrocarbons from the comminuted material.
35. The treatment apparatus as recited in claim 34, wherein the centerless helical screw conveyor comprises a helical bar.
36. The treatment apparatus as recited in claim 35, wherein the helical bar has a rectangular cross section.
37. The treatment apparatus as recited in claim 36, wherein the helical bar has a square cross section having 1-inch sides.
38. The treatment apparatus as recited in claim 34, wherein the centerless helical screw conveyor comprises a centerless helical screw conveyor having variable flight pitch.
39. A system for processing comminuted material containing carbon and hydrogen to produce liquid hydrocarbons, the system comprising:
a comminuted material feeder;
a hopper adapted to receive the comminuted material from the feeder;
at least one valve adapted to receive the comminuted material from the hopper;
an elongated cylindrical chamber having a first end adapted to receive the comminuted material from the at least one valve with little or no oxygen;
a centerless helical screw conveyor mounted for rotation in the elongated cylindrical chamber, and adapted to transfer the comminuted material from the first end of the chamber to the second end;
means for heating the cylindrical chamber to a temperature sufficient to produce gaseous hydrocarbons from the comminuted material at a first temperature and carbon-containing solids;
at least one discharge from the chamber for the gaseous hydrocarbons;
a first heat exchanger adapted to cool the gaseous hydrocarbons to a second temperature lower than the first temperature and condense a first liquid hydrocarbon from the gaseous hydrocarbons and a first cooler stream of gaseous hydrocarbons at a second temperature lower than the first temperature;
a second heat exchanger adapted to cool the first cooler stream of gaseous hydrocarbons to a third temperature, lower than the second temperature, to condense a second liquid hydrocarbon, different from the first liquid hydrocarbon, from the first cooler stream of gaseous hydrocarbons and a second cooler stream of gaseous hydrocarbons; and
a discharge at the second end of the chamber for the carbon-containing solids.
Description
    CROSS-REFERENCE TO RELATED APPLICATION
  • [0001]
    This application claims priority from pending U.S. Provisional Patent Application 60/864,529, filed on Nov. 6, 2006, the disclosure of which is included by reference herein in its entirety.
  • BACKGROUND
  • [0002]
    1. Field of the Invention
  • [0003]
    The present invention relates to the processing of materials having organic components, such as, used tires, to recover usable hydrocarbons, such as fuels, and/or metals. In particular, aspects of the present invention include processes for treating used tires to recover usable fuels.
  • [0004]
    2. Description of Related Art
  • [0005]
    Used tires can pose significant environmental problems attendant to piles of discarded tires and also can create fire hazards. In the United States, nearly 300 million tires are discarded each year in addition to the estimated one billion scrap tires that are already in some form of storage. These numbers are according to the United States Environmental Protection Agency.
  • [0006]
    Tires are highly engineered materials and are generally composed of rubber, carbon black, steel, fabric, sulfur, and additives, among other components. Styrene-butadiene rubber is most commonly used in the manufacture of automobile and truck tires. Various carbon blacks are used in tires to strengthen the rubber and improve the resistance of the rubber to abrasion. In addition to used tires, a large amount of commodity plastics or polymers are discarded each year. Although collection and recycling of common waste polymers is more prevalent today, still a large portion of these materials is still discarded because of the cost of recycling and only limited technologies are available to sustain economically viable recycling.
  • [0007]
    A substantial effort has been directed toward finding uses for used tires, including potential uses as fuel in various kilns and boilers and in rubber product applications. Techniques have also been studied to recover material values (as opposed to destructive burning), but these techniques have been largely unsuccessful for technical or economic reasons.
  • [0008]
    One known technology, pyrolysis, which as been described as suitable for addressing these discarded materials, involves the use of high-temperature, thermal degradation of the material in tires and other materials, in the absence of oxygen. This process is typically referred to as “pyrolysis.” Pyrolysis can (depending upon the technology and conditions employed) convert feed materials, such as, used tires and other materials containing carbon, hydrogen and oxygen, into liquid hydrocarbon fuels; gaseous materials, for example, mixtures of CO and H2 commonly referred to as synthesis gas or simply “syngas”; and elemental carbon (C) of varying quality. Each of these resultant materials can be valuable products. However, because pyrolysis technology and conditions prevalent heretofore, typically, instead of producing quality products, the results of prior art pyrolysis processing have commonly been the production of low value hydrocarbons, poor quality syngas, and low activity carbon black, among other things. It is not evident that any tire pryolysis has been in commercial operation for sustained periods economically producing commercial quality syngas or carbon blacks. Though some of those attempts appear to have been technically possible and/or may have been successful in pilot scale demonstrations, the technologies used did not allow for appropriate up-scaling or commercialization of the process because of the difficulty in reliably processing the material in an economical manner.
  • [0009]
    In view of the foregoing, a desirable process would be capable of processing used tires and other material containing carbon, hydrogen, and oxygen to yield commercial hydrocarbon products and other valuable materials. Such a process would also desirably recover commercial-quality steel and commercial-quality carbon, for example, as commercial-quality carbon black, from the feedstock principally comprised, for example, of used tire rubber.
  • [0010]
    Aspects of the present invention are directed to a pyrolytic conversion process and a pyrolytic conversion apparatus that address the aforementioned needs and provide a commercially viable apparatus and methods for substantially continuously converting such materials into useful hydrocarbons and other usable materials.
  • BRIEF SUMMARY OF ASPECTS OF THE INVENTION
  • [0011]
    Aspects of the present invention provide methods and apparatus for substantially continuously treating feed materials containing compounds containing to produce usable liquid hydrocarbons, such as fuel oil, and other usable products. One aspect of the invention is a method of treating one or more feed materials containing compounds containing carbon, hydrogen, and oxygen material in one or more elongated pyrolysis chambers, with inlets and outlets, the method including (1) feeding the feed material into an inlet zone of the pyrolysis chamber, (2) substantially continuously conveying the feed material through the pryolysis chamber from the inlet zone to an outlet zone while simultaneously removing build-up of feed material or the pryolysis products thereof from the inner walls of the pyrolysis chamber, (3) maintaining the temperature and residence of feed material and pyrolysis products thereof within the pyrolysis chamber at a level sufficiently high to pryolyze the feed material to at least one of liquid and gaseous hydrocarbons, yet sufficiently low to avoid unduly converting carbon compounds to elemental carbon; and (4) substantially continuously removing hydrocarbons and other products formed in the pyrolysis process from the outlet zone of the pyrolysis chamber.
  • [0012]
    The present invention also provides an apparatus for pyrolyzing feed materials containing compounds containing carbon, hydrogen, and oxygen material, the apparatus including: (1) one or more elongated pryolysis chambers each have one or more inlets and one or more outlets, and of suitable construction for the containment of the feed material and at least one of a liquid, a gaseous, and a solid pyrolysis products thereof; (2) means for continuously conveying the feed material and pyrolysis products thereof through the pyrolysis chamber while substantially simultaneously removing any build-up of feed material and the pyrolysis products thereof from the interior walls of the pyrolysis chamber; (3) means for maintaining the temperature and residence time within the pyrolysis chamber at levels sufficiently high to pyrolyze the air-extracted feedstock to hydrocarbons, yet sufficiently low to avoid unduly converting carbon compounds to elemental carbon; and (4) means for substantially continuously removing hydrocarbons formed in the pyrolysis chamber through one or more of said outlets.
  • [0013]
    Another aspect of the invention is a method of treating one or more feed materials containing carbon and hydrogen compounds in an elongated pyrolysis chamber having an inner surface, at least one material inlet, and at least one outlet, the method including: (1) introducing the feed material into the material inlet of the pyrolysis chamber; (2) continuously conveying the feed material through the pyrolysis chamber while substantially simultaneously removing build-up of feed material or the pyrolysis products thereof from the inner surface of the pyrolysis chamber; (3) maintaining a temperature of the feed material and pyrolysis products thereof within the pyrolysis chamber at a level sufficiently high to pyrolyze the feed material to form gaseous hydrocarbons; and (4) discharging the gaseous hydrocarbons from the at least one outlet of the pyrolysis chamber. In one aspect, the one or more feed materials may comprise comminuted tires, for example, comminuted used automobile or truck tires.
  • [0014]
    Another aspect of the invention is an apparatus for pyrolyzing one or more feed materials containing carbon and hydrogen compounds, the apparatus including (1) an elongated pyrolysis chamber having an inner surface, one or more inlets for introducing the feed material, and one or more outlets; (2) means for continuously conveying the feed material and pyrolysis products thereof through the pyrolysis chamber while substantially simultaneously removing any build-up of feed material and the pyrolysis products from the inner surface of the pyrolysis chamber; (3) means for maintaining the temperature within the pyrolysis chamber at a level sufficiently high to pyrolyze at least some of the feed material to gaseous hydrocarbons; and (4) means for discharging the gaseous hydrocarbons through the one or more outlets. In one aspect, the means for continuously conveying the feed material may be a rotating helical center-less screw mounted for rotation within the pyrolysis chamber. The helical center-less screw may include a plurality of flights sized to a provide clearance between the flights and the interior surface of the pyrolysis chamber. In another aspect, the means for continuously conveying the feed material may further comprise an initial portion, adjacent the material inlet, including means for reducing a size of the feed material and/or means for promoting conveyance of the material through the chamber. The pyrolysis chamber may also include means for cooling the pyrolysis products, for example, internally or externally of the chamber.
  • [0015]
    A further aspect of the invention is a method for substantially continuously treating comminuted material containing carbon and hydrogen, the method including introducing the comminuted material to an elongated chamber having little or no oxygen; transferring the comminuted material through the elongated chamber; heating the comminuted material to a temperature sufficient to pyrolyze the comminuted material to produce gaseous hydrocarbons and at least some carbon-containing solids; discharging the gaseous hydrocarbons from the chamber; cooling at least some of the gaseous hydrocarbons to liquefy the hydrocarbons; and discharging the carbon-containing solids from the chamber. In one aspect, transferring may comprise transferring while minimizing buildup of the comminuted material and the carbon-containing solids on an insider surface of the elongated chamber. For example, in one aspect, minimizing the buildup of material and solids may comprise conveying a scraping device over the inside surface of the elongated cylinder, for instance, transferring the material with a center-less screw conveyor having at least one flight that bears against the inside surface of the elongated chamber. In one aspect, the comminuted material containing carbon and hydrogen may comprise comminuted tires, for example, automobile or truck tires.
  • [0016]
    A still further aspect of the invention is a method from producing liquid hydrocarbons from comminuted carbon and hydrogen containing material, the method including introducing the comminuted material to a chamber having little or no oxygen; heating the comminuted material to a temperature sufficient to produce gaseous hydrocarbons at a first temperature; cooling the gaseous hydrocarbons to condense a first liquid hydrocarbon from the gaseous hydrocarbons and a first cooler stream of gaseous hydrocarbons at a second temperature lower than the first temperature; and cooling the first cooler stream of gaseous hydrocarbons to a third temperature, lower than the second temperature, to condense a second liquid hydrocarbon from the first cooler stream of gaseous hydrocarbons and a second cooler stream of gaseous hydrocarbons. In one aspect, the method may further comprise cooling the second cooler stream of gaseous hydrocarbons to a fourth temperature, lower than the third temperature, to condense a third liquid hydrocarbon from the second cooler stream of gaseous hydrocarbons and a third cooler stream of gaseous hydrocarbons. As above, in one aspect, the comminuted material containing carbon and hydrogen may comprise comminuted tires.
  • [0017]
    A still further aspect of the invention is a treatment apparatus for comminuted material containing carbon and hydrogen, the apparatus including an elongated cylindrical chamber having a first end and a second end; a center-less helical screw conveyor mounted for rotation in the elongated cylindrical chamber; means for rotating the center-less helical screw conveyor to transfer the comminuted material from the first end to the second end; and means for heating the cylindrical chamber to a temperature sufficient to produce gaseous hydrocarbons from the comminuted material. In one aspect, the center-less helical screw conveyor comprises a helical metal bar. In one aspect, the center-less screw conveyor is substantially supported at one end, wherein the conveyor includes a free end allowed to move within the chamber.
  • [0018]
    An even further aspect of the invention is a system for processing comminuted material containing carbon and hydrogen to produce liquid hydrocarbons, the system including a comminuted material feeder; a hopper adapted to receive the comminuted material from the feeder; at least one valve adapted to receive the comminuted material from the hopper; an elongated cylindrical chamber having a first end adapted to receive the comminuted material from the at least one valve with little or no oxygen; a center-less helical screw conveyor mounted for rotation in the elongated cylindrical chamber, and adapted to transfer the comminuted material from the first end of the chamber to the second end; means for heating the cylindrical chamber to a temperature sufficient to produce gaseous hydrocarbons from the comminuted material at a first temperature and carbon-containing solids; at least one discharge from the chamber for the gaseous hydrocarbons; a first heat exchanger adapted to cool the gaseous hydrocarbons to a second temperature lower than the first temperature and condense a first liquid hydrocarbon from the gaseous hydrocarbons and a first cooler stream of gaseous hydrocarbons at a second temperature lower than the first temperature; a second heat exchanger adapted to cool the first cooler stream of gaseous hydrocarbons to a third temperature, lower than the second temperature, to condense a second liquid hydrocarbon, different from the first liquid hydrocarbon, from the first cooler stream of gaseous hydrocarbons and a second cooler stream of gaseous hydrocarbons; and a discharge at the second end of the chamber for the carbon-containing solids.
  • [0019]
    These and other aspects, features, and advantages of this invention will become apparent from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0020]
    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention will be readily understood from the following detailed description of aspects of the invention taken in conjunction with the accompanying drawings in which:
  • [0021]
    FIG. 1 is a schematic illustration of a process and apparatus of the present invention.
  • [0022]
    FIGS. 2A, 2B, and 2C are side elevation views of rotatable helical screw conveyors that may be used in aspects of the invention.
  • [0023]
    FIG. 2D is an end view of the screw conveyors shown in FIGS. 2A, 2B, and 2C.
  • [0024]
    FIG. 3 is a schematic illustration of one aspect of the invention in which a plurality of parallel processing systems is provided.
  • [0025]
    FIG. 4 is front elevation view of a treatment system according to another aspect of the invention.
  • [0026]
    FIG. 5 is a left side elevation view of the treatment system shown in FIG. 5.
  • [0027]
    FIG. 6 is right side elevation view of the treatment system shown in FIG. 5.
  • [0028]
    FIG. 7 is a schematic cross-sectional view of a condensing device according to one aspect of the invention.
  • DETAILED DESCRIPTION OF ASPECTS OF THE INVENTION
  • [0029]
    Aspects of the present invention comprise apparatus and processes for treating feed materials, for example, feed materials containing carbon, hydrogen, and oxygen compounds to produce usable hydrocarbon materials and other substances. In one preferred aspect, the feed material may be used tires, that is, used automobile and truck tires, although a wide variety of other feed materials containing compounds containing carbon, hydrogen, and oxygen material may be used in addition to or in lieu of used tires. Used tires are preferred because of their composition (particularly the recoverable components thereof), cost (used tires are frequently obtainable at a no cost or for a nominal fee, other than costs of transportation and handling) and the environmental mandates against improper disposal. However, other material such as plastics, polymers, rubbers, and other organic/petroleum-based materials are also suitable. In some instances, even when processing the preferred feeds (that is, used tires), it may be desirable to co-feed in various materials, for example, materials higher in carbon and/or hydrogen content than tires to adjust the quality of the syngas or hydrocarbon products being produced, such as, fuel oils or petroleum coke.
  • [0030]
    The feed materials may be in various physical forms and sizes, however, when processing used tires, it is preferable that the tires have been shredded to a size of less than about 2 inch “chucks,” for example, by processing the tires with one or more commercially available shredders, prior to being fed into the pyrolysis chamber. Used tires are commonly also shredded and sized to what is known as “crumb,” from which the metal content may have been removed, and my also be used as feed material. However, “chunks” of material are equally or more suitable in the practice of aspects of the invention, since these materials are commonly less expensive and typically still contain the metal components of the tire, which can be beneficially recovered.
  • [0031]
    Preferably, in one aspect, the feed material should be free or relatively free of most inorganic materials (for example, concrete, soil, refuse, etc.) which may minimize the quality of various products produced according to aspect of the invention (for example, the quality of the recovered carbon), but the presence of metals (for example, steel, which is a common component of most tires) may be generally desirable and can be recovered as a valuable product, as discussed hereinafter. If necessary or desirable, steel or other magnetic-sensitive material may be removed by commercially available magnetic separators before, during, or after processing according to aspects of the invention.
  • [0032]
    Depending upon the degree of inclusion of material other than carbon, hydrogen, and oxygen in the specific feeds, in one aspect of the invention, it may be desirable to separate out some components (for example, inogranics, such as concrete) from the feed material prior to feeding the material into the pyrolyzer. However, as mentioned above, metals can be economically desirable, and may be removed from the chamber during or after treatment (for example, for technical and/or economic reasons).
  • [0033]
    The use of catalysts (for example, AlCl3), as described in some prior art literature as possibly assisting in the conversion of feed material, is not required for the practice of aspects of the invention, but may be introduced to the process, if desired.
  • [0034]
    In one aspect, the feed materials are fed into an elongated pyrolysis chamber in a manner designed to limit the introduction of air, since air (which is principally oxygen and nitrogen), may adversely affect the quality of the syngas or gaseous hydrocarbons produced. In one aspect, a double air lock is used at the point of feed introduction to minimize or prevent the introduction of air. An air lock may also be used at the exit of the chamber.
  • [0035]
    A schematic illustration of a process and an apparatus 10 according to one aspect of the present invention is shown in FIG. 1. Apparatus 10 includes a cylindrical treatment vessel or “pyrolyser” 12 having a first end 14 and a second end 16 containing a conveyor 18, for example, a screw conveyor, adapted to transfer comminuted material from first end 14 to second end 16. Conveyor 18 is driven by a motor 20, or other source of motive force, as is conventional, via speed reducer 21.
  • [0036]
    In the following discussion and in the subsequent claims, the material treated in aspects of the invention is referred to as “comminuted” material. The term comminuted is meant to imply any material that is provided as particles or pieces, but is not intended to limit the size or shape of the material provided. The size of the material may vary from micron scale and smaller to centimeter scale or larger. In one aspect, the size of the material treated may be limited to a size that can effectively be treated in vessel 12 while providing little or no untreated material in the resulting product. The comminuted material treated in vessel 12 may include any material containing carbon and hydrogen that when heated in an atmosphere having little or no oxygen produces gaseous hydrocarbons and carbon-containing solids. It is contemplated that the material treated in vessel 12 comprise any petroleum-based material, for example, elastomers or plastics, for example, recycled plastics and the like. One source of feed material that may be provided are rubber tires, for example, scrap tires, comminuted by conventional shredding devices or grinders to provide tire particles or “crumb” rubber tire pieces.
  • [0037]
    As discussed above, since tires are engineered materials containing an array of materials and additives, it is likely that comminuted tire material include metal and fabric belts that may also be introduced to apparatus 10. These materials may be isolated if desired. For example, the ferromagnetic content of the tires may be isolated by one or more conventional magnets. However, in aspects of the invention, apparatus 10 is tolerant of such material and no separation or isolation of material may be necessary.
  • [0038]
    Regardless of the source and size of the comminuted material, the material may typically be introduced to system 10 by a conveyor 22. Conveyor 22 may be any conventional conveyor, for example, a belt conveyor having material transferring ridges or projections. Conveyor 22 may introduce the comminuted material to an open hopper 24 as indicated by arrow 26. The comminuted material is generally indicated by comminuted material pieces 28 in FIG. 1. Hopper 24 directs the material 28 through one or more conduits 30 and 32 and introduces material 28 to first end 14 of conveyor 12. In order to minimize the air introduced to vessel 12, specifically, oxygen and nitrogen, one or more isolation devices 34 are typically provided in conduits 30 and 32. Isolation device 34 may be any device that limits the content of oxygen and nitrogen introduced to vessel 12 while permitting the passage of material 28, for example, device 34 may comprise one or more valves.
  • [0039]
    The feed mechanism that introduces material 28 to apparatus 10 may also preferably ensure that substantially all of the air contained in the waste is extracted, for example, using commercially available isolation devices, such as, auger extruder feeders or ram feeders. In addition to the above-described aspects of feed introduction, it is to be understood that other conventional aspects of feed preparation (for example, screening, sorting, or drying) may be provided before or during transferring material 28 to apparatus 10.
  • [0040]
    In one aspect, the inventors have found that isolation device 34 may comprise at least two flapper-type valves, for example, flapper valves provided by the Plattco Corporation, or their equivalent. In one aspect, at least two flapper valves are provided, one positioned above the other, and a void space is provide between the two flapper valves. This void space may be purged with a non-oxygen and non-nitrogen gas, for example, carbon dioxide or an inert gas, such as argon or helium. The timing of the opening and closing of the two flapper valves may be provided whereby the upper valve is open and the lower valve closed whereby material 28 is allowed to fill the void space between the two valves. The upper valve is then closed while the lower valve remains closed while the space is purged with the purge gas. After purging, the lower valve is opened to transfer the material with little or no oxygen or nitrogen to vessel 12.
  • [0041]
    In another aspect, the isolation device 34 may be a star-type feeder having a rotor having a plurality of pockets that receive and discharge material 28 to vessel 12. A pocket of the star-type feeder may also be purged with an inert gas to minimize the oxygen introduced to the vessel 12. In another aspect, an extrusion-type feeder may also be used where the material 28 is forced through a restriction whereby little or no air is introduced to vessel 12.
  • [0042]
    Vessel or chamber 12, which may also be referred to as a “pyrolyzer,” a “treatment vessel,” or a “reactor” 12, used in the practice of aspects of the present invention is preferably an elongated pyrolysis chamber in the form of a cylindrical reactor. Vessel 12 may be horizontally positioned or oriented or may have a slight upward pitch or downward pitch. Although a U-shaped or other shaped reactor could be used, the vessel 12 may typically be a straight, horizontally positioned cylinder, free of any significant bends or curves. The cylindrical reactor 12 may be constructed of steel, for example, stainless steel, although other materials of sufficient structural integrity and thermal properties would also be suitable. In one aspect, reactor 12 is a horizontally positioned, cylindrical reactor having an internal diameter (ID) of about 12 inches to about 16 inches that may be used for optimal heat transfer and efficiency, with the cylindrical reactor having a length of between about 30 feet and about 40 feet. If higher feed rates are desired, using two or more reactors in parallel, would be preferable (for example, to help ensure uniform heat transfer and processing) as opposed to increasing the size of a single reactor. One or more reactors may be used, for example, two reactor vessels in parallel may be used as shown in FIG. 3.
  • [0043]
    Vessel 12 may typically be a cylindrical vessel, for example, a generally circular cylindrical vessel, though vessel 12 may also comprise a unshaped trough. In one aspect, when vessel 12 is circular cylindrical, it may have an inside diameter ranging from about 6 inches to about 4 feet, but may typically be about 8 to about 18 inches inside diameter, for example about 12 inches in inside diameter. Again, vessel 12 may be made from any conventional structural material capable of handling the operating temperatures, for example, steel, aluminum, or titanium, but is typically made from stainless steel, for example, 304 or 304L stainless steel. The length of vessel 12 may vary from about 6 feet to 200 feet, but is typically about 25 to 50 feet in length, for example, about 30 feet in length. Vessel 12 may be operated under vacuum or at an overpressure, that is, a pressure above atmospheric pressure. Vessel 12 may typically be substantially horizontal or, in one aspect, may be directed at an angle to the horizontal, for example, an upward angle. In this aspect of the invention, the upward angle or inclination of vessel 12 promotes the flow of gaseous hydrocarbons produced toward the second end 16 of vessel 12.
  • [0044]
    After material 28 is introduced to vessel 12, material 28 is transferred from first end 14 to second end 16 by conveyor 18 driven by motor 20 and gear reducer 21. In one aspect, conveyor 18 may typically be supported at only a first end, that is, an end of conveyor 18 operatively driven by motor 20, and have a second free end opposite the first end. According to aspects of the invention, the second free end may be free to flex or deflect, for example, flex or deflect as the material loading on conveyor 18 varies, for example, varies along the length of chamber 12 or about the inside diameter of chamber 12. The horsepower of motor 20 may vary depending upon the size of conveyor 18 and the nature of material 28 being transferred. Typically, motor 20 may have a horsepower of at least about 5 Hp to about 50 Hp. Reducer 21 may be chosen whereby conveyor 18 is rotated from about 0.25 rpm to about 10 rpm depending upon the nature of material 28 and the desired treatment time and temperature. For example, when treating comminuted tire material, conveyor 18 may be driven at about 1 rpm. Conveyor 18 may comprise any type of conveyor adapted to transfer comminuted material, for example, a screw conveyor, a drag chain conveyor, a belt conveyor, and the like. In one aspect of the invention, conveyor 18 comprises a screw conveyor. Screw conveyors that may be used according to aspects of the invention is the screw conveyors 18A, 18B, and 18C illustrated in FIGS. 2A, 2B, and 2C, respectively, discussed below. Conveyer 18A, 18B, or 18C may have a constant or variable flight pitch. For example, the pitch of the flights of conveyor 18A, 18B, or 18C may be varied to vary the residence time in different sections of vessel 12 during treatment.
  • [0045]
    As shown in FIG. 1, reactor chamber 12 includes a rotating helical conveyor 18, for example, a center-less screw or coil conveyor extending along the chamber 12. As shown in FIGS. 2A, 2B, and 2C, the helical center-less screw or coil conveyor 18A, 18B, or 18C typically includes a helical screw 50 having multiple flights or coil loops 49, a first end 51 mounted to drive plate 54, and a second free end 53 opposite first end 51. Drive plate 54 may be operatively connected to motor 20 or gear reducer 21 via shaft 52. In one aspect, flights or loops 49 may be appropriately sized to provide a close tolerance between the flights or loops 49 and the interior surface of the walls of the chamber 12 (indicated by phantom lines 55) whereby material 28 and any pyrolysis produces are continuously conveyed through chamber 12. In one aspect, the center-less conveyor 18A having screw or coil 50 is significantly different in design and function from conventional auger-type feeders or other conveyors, which typically include a shaft around which flights, blades, or other components turn to convey material in a conduit. For example, according to aspects of the invention, since uniform heating of material is preferred to provide optimal product formation without undue charring, the present invention desirably provides a conveying means with no shaft, or other hot spots, upon which the undesirable formation and buildup of components can occur. Further, the close clearance (typically less than 1 inch) between the outermost extension of the flights or coils 49 and the interior surface of the walls 55 of chamber 12 results in removal of any build-up of feedstock and/or pyrolysis products from the interior walls 55 of the chamber 12.
  • [0046]
    The number of coils or flights 49 and the spacing thereof (which need not be uniform) can be optimally selected based upon the dimensions of the chamber 12 and other design considerations. For example, in a thirty-foot long cylindrical reactor chamber 12, a center-less screws 18A having 47 flights, that is, about 6 inches between flights, is suitable. Similarly the pitch of the flights or coils 49 can optimally selected based similar considerations and the type of feed material 28 being processed.
  • [0047]
    FIG. 2B illustrates a side elevation view of another screw conveyor 18B that may be used as conveyor 18 in apparatus 10 shown in FIG. 1. Conveyor 18B may have all the attributes of conveyor 18A, including a helical screw 50 having multiple flights or coil loops 49, a first end 51 mounted to a drive plate 54, and a second free end 53 opposite first end 51. However, conveyor 18B also may include a screw 60 having flights 64 that assist or promote the movement of material 28 along chamber 12, for example, away from the feed inlet of chamber 12. Screw 60 may be mounted to plate 54 and also be driven by motor 20. In one aspect, screw 60 may be limited in length, depending upon the size of chamber 12 and the rate of feed of material 28. For example, screw 60 may extend only between about 5 to about 15 percent of the length of chamber 12, for example, from 3 feet to 10 feet from first end 14 of vessel 12.
  • [0048]
    FIG. 2C illustrates a side elevation view of another screw conveyor 18C that may be used as conveyor 18 in apparatus 10 shown in FIG. 1. Conveyor 18C may have all the attributes of conveyor 18A or 18B, including a helical screw 50 having multiple flights or coil loops 49, a first end 51 mounted to a drive plate 54, and a second free end 53 opposite first end 51. However, conveyor 18C also may include a one or more second internal helical screws 160, similar to helical screw conveyor 50, having coils or flights 149, a first end 151 mounted to a drive plate 54, and a second free end 153 opposite first end 151, that assists or promotes the movement of material 28 along chamber 12, for example, away from the feed inlet of chamber 12. One or more screws 160 may be mounted to plate 54 and also be driven by motor 20. In one aspect, one or more screws 160 may be limited in length, depending upon the size of chamber 12 and the rate of feed of material 28. For example, one or more screws 160 may extend only between about 5 to about 15 percent of the length of chamber 12, for example, from 3 feet to 10 feet from first end 14 of vessel 12. In addition, one or more screws 160 may comprise a first screw 160 extending between about 5 percent to about 15 percent of the length of chamber 12, and a second screw 160 (not shown), extending between about 10 percent to about 40 percent of the length of chamber 12. However, in other aspects of the invention, one or more screws 160 may have any convenient length, for example, one or more screws 160 may have the same length as screw 50, for instance, extend substantially the entire length of vessel 12, or one or more screws 160 may extend only about midway along vessel 12 while screw 50 extends substantially the entire length of vessel 12. In other aspects, one or more screws 160 may be longer or shorter than screw 50. One or more screws 160 may have the same or different pitch, that is, the number coils per unit length, than screw 50. For example, one or more screws 160 may have a larger or smaller pitch or a variable pitch, compared to the pitch of screw 50. In one aspect, one or more screws 160 may comprise a first screw 160 having a first pitch mounted to plate 54 and having an outside diameter smaller than the inside diameter of screw 50, and a second screw 160 (not shown) having a second pitch, different from the first pith, mounted to plate 54 and having an outside diameter smaller than the inside diameter of first screw 160. Additional screws 160 having a smaller outside diameter of second screw 160 are also conceived in aspects of the invention.
  • [0049]
    In one aspect, the flights or coils 49 and 149 of conveyor 18A, 18B, or 18C may be constructed from bar stock, for example, from 1-inch square 304 stainless steel bar stock. The use of bar stock can facilitate construction while providing the desired conveying function; however, in other aspects, flights or coils 49 or 149 may be fabricated from elongated bar stock having a circular, a rectangular, or a triangular cross section, among other shapes. The coils or flights 49 or 149 may be made of stainless steel, for example, 304 or 340L stainless steel, thought other materials of sufficient strength/flexibility may be used. In one aspect, coils or flights 49 or 149 may effectively convey material 28 and pyrolysis produces through chamber 12 by providing at least some displacement or “scraping” of material from the insider surface of the walls 54 of chamber 12, for example, to minimize or prevent the buildup of material on the inside surface of chamber 12 that may otherwise interfere with the proper operation of apparatus 10. In one aspect, the coils or flights 49 or 149 of conveyors 18A, 18B, or 18C may convey material along the inside surface of chamber 12 by flexibly deflecting from the reactor walls in a “slinky-like” fashion or movement due to the flexibility of the center-less conveyor 50 and/or 160. In contrast, prior art conveyors supported at both ends or made from unduly rigid bars are typically more susceptible to plugging or jamming with feed material, for example, as commonly occurs when conveying comminuted tire material with rigid auger-type screw conveyors. According to aspects of the present invention, the material of construction of the coils or flights 49 and 149 have sufficient thermal and structural properties for the temperature and stress to which the coils or flights 49 and 149 will be subject, but are also flexible and can deflect. The helical center-less screw conveyor 50 and 160 are typically driven by motor 20 operatively connected to first end 51 or 151 of conveyor 18A, 18B, or 18C and unsupported at second end 53 or 153, other than by contact with the inside surface of chamber 12. Conveyors 18A, 18B, and 18C are typically rotated at a relatively slow speed, that is, at a low number of revolutions per minute (for example, about 1 RPM), to help ensure uniform mixing and heat transfer.
  • [0050]
    According to one aspect of the invention, the inclusion of a rotating helical centerless coil screw conveyor 18A, 18B, or 18C within pyrolysis chamber 12 ensures optimal movement of material 28 and pyrolysis products and uniform mixing. For example, in one aspect, conveyor 18A, 18B, or 1C provides thorough mixing (including allowing material being processed to “roll-back” over itself) as well as at least some grinding of carbon pyrolysis products and other solid material into finer form. However, depending on the diameter of the pyrolysis chamber 12 compared to the size of the material 28 being fed to chamber 12, means to assist in the reduction in the size of the feed material 28 and/or in the conveying of feed material though chamber 12 may be provided in chamber 12. For example, in one aspect, additional or modified coils 49 or 149 may be provided at the first or feed end 14 of pyrolysis chamber 12. For instance, as shown in FIG. 2A, the feed into and initial processing in the chamber 12 may be enhanced by providing a first portion (for example, having a length of about 2 to about 4 feet) of conveyor 18A be modified to have vane-like flights or projections 66 (shown in phantom in FIGS. 2A and 2D) mounted to the flights or coils 49 in this region to help break-up and/or propel feed material 28. This modified conveyor 18A with vane-like flights or projections 66 may be effective when the relative size of material 28 being introduced to chamber 12 is large (for example, 12 inches in width or diameter). As an alternative, the initial portion of the center-less coil conveyor 18A, 18B, or 18C adjacent first end 51 may be replaced with more traditional (non-centerless) conventional flights.
  • [0051]
    During transport of material 28 from first end 14 to second end 16, the material 28 is heated to a temperature at which gaseous hydrocarbons are released. This temperature is typically at least about 400 degrees C., but may range from about 450 degrees C. to about 650 degrees C. The processing temperature is dependent on the types of feed and the mix of products desired. For example, a temperature range of about 450 to about 475 degrees C. (that is, about 842 to 887 degrees F.) is typically optimal for processing a shredded tire feed, but if one wants to maximize the recovery of liquid hydrocarbon products, a somewhat lower temperature may be used; for more gaseous products, a somewhat higher temperature may be used.
  • [0052]
    This heating is typically provided by heating device 36 shown in FIG. 1. Heating device 36 may comprise any conventional heating device adapted to heat at least a portion of vessel 12 and its contents. Heating device 36 may be resistive heating device, for example, one or more electrical heating coils mounted to vessel 12. Heating device 36 may comprise an oil or gas heater having a fuel inlet and one or more fuel burners mounted to heat vessel 12. Heating device 36 may be adapted to burn one or more of the gaseous or liquid hydrocarbons produced by apparatus 10. Vessel 12 may be insulated by a suitable insulation material to minimize the loss of heat from vessel 12.
  • [0053]
    Heating device 36 may be a gas-fired heat exchanger, for example, a heat exchanger jacketing reactor chamber 12, but heating device 36 may also be one or more electrical heaters, though any other conventional heating means may be suitable for heating chamber 12 and its contents. In one aspect, a gas-fired heat exchanger may be used, since syngas or other gaseous hydrocarbons produced by the process of this invention may be recycled back to and used as all or part of the gas fed to the gas-fired heat exchanger. Since cooling and product recovery occurs at or toward the outlet or second end 16 of reactor chamber 12, the outlet or second end 16 of chamber 12 may not need to be heated.
  • [0054]
    According to aspects of the invention, the temperature and residence time within the pyrolysis chamber 12 may be maintained at levels sufficiently high to pyrolyze the feed material 28 to hydrogen and carbon containing gases, for example, to carbon monoxide (CO), hydrogen (H2) and/or hydrocarbon gases, yet be at a sufficiently low temperature to avoid unduly charring the carbon compounds. For example, when processing used tires sized to about 2 inch chucks in a 12-inch stainless steel cylindrical reactor 12 about 32 feet in length, chamber 12 may electrically heated so that material 28 is heated to about 450 degrees C. to about 475 degrees C. with a residence time of about 30 to about 45 minutes. Under these conditions, the feed material 28 may be converted into a soft, gummy mass or soft, crumbly mass at about the midway point in the pyrolysis chamber 12 and may be sufficiently fluid to facilitate further processing in the chamber 12 and the separation of “cuts” of recovered gaseous, liquid, or solid products. In other aspects, the feed material 28 may be converted into a viscous, syrupy fluid at about the midway point in the pyrolysis chamber or near the first end 14 of the chamber 12. According to aspects of the invention, by using more efficient gas-fired heaters, a shorter residence time in chamber 12 can be provided.
  • [0055]
    The gaseous hydrocarbons released by the heating of material 28 in an atmosphere having little or no oxygen, that is, by pyrolysis, will vary depending upon the nature of the material 28 being processed. The gases released during pyrolysis exit vessel 12 via one or more discharge nozzles 38, see FIG. 1, and are passed through one or more conduits 40 to a condenser system 42. Examination of the gases released during the treatment of tires in vessel 12 according to aspects of the invention shows that these gases comprise a range of non-condensable gases, gaseous hydrocarbons, and volatile sulfur compounds (VSC), among other gases. Table 1 identifies one set of typical species of gases produced during the processing of tires. It is understood that the species identified in Table 1 are one set of gas species that can be generated according to aspects of the invention, and the actual gas species generated will vary depending upon the nature of the feed material and the treatment conditions.
  • [0000]
    TABLE 1
    Typical Chemical Analysis of Gases Produced
    According to Aspects of the Invention
    Volatile Sulfur Compounds
    Non-Condensable Gases Hydrocarbons Parts per
    Gas Volume % Gas Volume % Gas mill, (ppm)
    Nitrogen 0.33 Ethylene 8.26 Hydrogen Sulfide 577
    Oxygen Non detect. Ethane 8.34 Carbonyl Sulfide 437
    CO2 10.5 Propylene 6.24 Sulfur Dioxide Non detect.
    CO 2.56 Propane 4.17 Methyl Mercaptan 217
    Hydrogen 10.1 Isobutane 9.76 Ethyl Mercaptan 192
    Argon Non detect. n-Butane 3.15 Dimethyl Sulfide 10
    Methane 22.1 Butene 2.42 Carbon Disulfide 98
    Isopentane 2.04 Isopropyl Mecapt. 14
    n-Pentane 6.33 t-Butyl Mercapt. 3.0
    Pentene 1.42 n-Propyl Mercapt. 4.4
    Hexane 2.26 Methyl Ethyl Sulf. 4.2
    Thiophene. 321
    Isobutyl Mercapt. 0.5
    Dimethyl Bisulfide 5.6
    Others 230
  • [0056]
    Condenser system 42 is adapted to cool at least some of the gaseous species released from vessel 12 to produce at least one liquid hydrocarbon, for example, one or more oils of varying weights. The cooling in condenser system 42 may be effected in one or more heat exchangers 44 adapted to receive the gaseous hydrocarbons via one or more conduits 40 and a coolant, for example, water, via conduit 45. The coolant may be used repeatedly and recirculated through the two or more heat exchangers 44. The circulation of coolant through two or more heat exchangers may be practiced in a counter-current fashion, that is, with the coolest coolant cooling the coolest gaseous hydrocarbons, or in a co-current fashion, that is, with the coolest coolant cooling the hottest gaseous hydrocarbons. The condensed liquid hydrocarbon, for example, an oil, may be discharged from outlet conduit 46 and forwarded to further processing, for example, filtering, storage, or for a source of fuel for heating device 36. The non-condensed gaseous hydrocarbon, for example, methane, ethane, or propane, may be discharged from condenser system 42 via conduit 48. In one aspect of the invention, condenser system 42 may include one or more separation devices, for example, settling tanks, cyclone separators, or baffles, designed to isolate entrained solids, for example, carbon black, tramp material, ash, and the like, prior to introducing the gaseous stream to the condenser vessels.
  • [0057]
    According to one aspect of the invention, condenser system 42 is adapted to a perform “reverse condensation” of the gaseous hydrocarbons discharged from nozzles 38. According to this aspect, the gaseous hydrocarbon stream is sequentially condensed to a first liquid hydrocarbon fraction, for example, an oil, and then a second liquid hydrocarbon fraction of lower weight than the first liquid hydrocarbon fraction. For example, the first liquid hydrocarbon fraction may be a fuel grade oil and the second liquid hydrocarbon fraction may be kerosene-grade oil or a gasoline-type liquid hydrocarbon. In one aspect, at least three or four heat exchangers 44 are provided in condenser system 42 whereby at least three or four liquid hydrocarbon fractions are provided.
  • [0058]
    Table 2 identifies the results of the chemical analysis of four liquid samples produced by means of condensing the gases discharged from vessel 12. As shown, the liquids, typically, hydrocarbons, are primarily carbon and hydrogen, but nitrogen and sulfur are also present. Though not indicated in Table 2, Gas Chromatograph/Mass spectrometer analysis of fluid samples produced by aspects of the invention reveal that a broad spectrum of hydrocarbons are produced by aspects of the invention.
  • [0000]
    TABLE 2
    Typical Chemical Analysis of Hydrocarbon Liquids Produced
    According to Aspects of the Invention, Weight Percent
    Constituent Sample #1 Sample #2 Sample #3 Sample #4
    Sulfur 0.90 0.91 0.75 0.73
    Ash 0.05 0.02 0.01 0.03
    Carbon (Total) 89.6 88.86 85.43 87.01
    Hydrogen 9.71 10.00 10.08 10.94
    Nitrogen 0.36 0.32 0.27 0.20
    Specific Gravity 0.9524 0.9265 0.8850 0.8812
    BTU Value [BTU/lb] 17868.90 17518.60 15194.60 15429.80
  • [0059]
    The non-volatile material, for example, carbon black, steel, and other inorganic material that remains in the vessel 12 after the volatile compounds have been driven off are discharged from outlet 50. These materials may be forwarded to further processing, for example, screening, metal removal, or to storage for latter use or recycling. Table 3 lists the results of chemical analysis of the typical constituents of solids removed from vessel 12 according to aspects of the invention. As indicated, the solids produced are primarily carbon.
  • [0000]
    TABLE 3
    Typical Chemical Analysis of Solids Produced
    According to One Aspect of the Invention
    Constituent Composition (%)
    Carbon 82.73
    Hydrogen 2.36
    Nitogen 0.31
    Sulfur 2.85
    Ash 11.31
    Oxygen 0.44
    Moisture 0.80
    Total ~100
    Dulong BTU Value 13,666.38 BTU-lb
  • [0060]
    According to aspects of the invention, the feed rate of material 28 through chamber 12 may be dependent upon several factors, including the diameter of reactor chamber 12 and the physical form and composition of feed material 28. In one aspect, the feed rate may be selected to optimize the uniform heating of material 28 and the uniform production of the desired pyrolysis products during processing. For example, when processing 2 inch chunks of used tires in as 12-inch diameter stainless steel cylindrical reactor chamber 12 described above, a processing rate of about one tire, for example, about 20 pounds, per minute may be provided.
  • [0061]
    The processing in chamber 12 may be practiced at various pressures. For example, maintaining a slight positive or over pressure in the reactor may be beneficial in embodiments in which production of gaseous hydrocarbons is sought to be maximized. Alternately, reactor 12 may be operated under vacuum, for example, to minimize potential safety issues.
  • [0062]
    In one aspect, reactor chamber 12 can be provided with multiple treatment zones, for example, at least three (3) treatment zones may be provided. For example, a heating zone, a cooling zone, and a recovery zone. The discussion of heating in the foregoing sections may apply to the what might be called the heating zone. However, in one aspect, the control of temperature (including by providing cooling fluid, such as, water) may be provided near or at the second end 16 or outlet of the chamber 12. Controlling the temperature of the second end 16 or outlet of chamber 12 may facilitate recovery of gaseous hydrocarbons. These gaseous hydrocarbons may be further treated as necessary or desirable. Additional processing to treat particulate and impurities in the syngas or hydrocarbon gas (for example, using plasma arc technology) may be employed as necessary or desirable depending on the desired quality of the gaseous hydrocarbons or syngas produced. In one aspect, at least some oxygen may be introduced to the process chamber 12 at one or more predetermined locations in order to promote the conversion of elemental carbon (C) to carbon monoxide (CO) or carbon dioxide (CO2), though CO generation may be undesirable due to its low heating value.
  • [0063]
    According to one aspect of the invention, when the processed feed material 28 is used tires, carbon and metal fractions may be produced by the process practiced in chamber 12. The carbon produced, for example, as characterized in Table 3 may be suitable for use as a coal substitute for heating or other processing. The metal fractions produced, for example, iron or steel, may comprise a high grade of steel that can be recycled.
  • [0064]
    FIGS. 2A, 2B, and 2C are side elevation views rotatable helical screw conveyors 18A, 18B, and 18C, respectively, that may be used in aspects of the invention. Conveyor 18A, 18B, or 18C may be mounted for rotation within vessel as illustrated by conveyor 18 in FIG. 1. Conveyors 18A, 18B, and 18C may be operatively connected and driven by motor/reducer 20/21 in FIG. 1. FIG. 2D is an end view of the screw conveyors 18A, 18B, and 18C shown in FIGS. 2A, 2B, and 2C, respectively, with certain features of conveyors 18B and 18C shown in phantom. As shown in FIG. 2A, conveyor 18A includes a helical transfer screw 50 having a first end 51 mounted to be driven by a shaft 52 operatively driven by motor 20 and a second end 53. For example, screw 50 may be driven by drive plate 54 which is mounted to shaft 52. As shown in FIG. 2A, only representative sections of screw 50 are illustrated. In one aspect, conveyor 18A may comprise a “center-less screw,” that is, a screw conveyor having no central shaft as is typically of screw conveyors. According to aspects of the invention, conveyor 18A conveys feed material 28 and any products of pyrolysis through vessel 12 from first end 14 to second end 16. For example, in one aspect, conveyor 18A may comprise a scraping device having at least one flight that bears against the inside surface of vessel 12, as shown in phantom as lines 55 in FIG. 2A. In one aspect, screw 50 of conveyor 18A is mounted at first end 51 to drive plate 54, but is unsupported at free second end 53, other than be contact with the inside surface of vessel 12, as represented by phantom lines 55. In one aspect, screw 50 is flexible and unsupported at second end 53 whereby the position of screw 50 in vessel 12 may vary depending upon the loading on screw 50. For example, in one aspect, the flexibility of center-less screw 50 permits screw 50 to flex under load and, for instance, deflect when contacting material that would obstruct or prevent the rotation of a non-flexible screw conveyor. In one aspect, the flexible, center-less screw 50 having free end 53 overcomes the disadvantages of conventional screw conveyors allowing the pyrolitic treatment disclosed herein possible. In another aspect, center-less screw 50 may be supported, for example, at end 53 or anywhere between first end 51 and second end 53, while still having sufficient flexibility to perform the desired transfer function. Conveyor screw 50 may be made from any metallic material, for example, steel, stainless steel, aluminum, or titanium, but is typically made from 304 stainless steel. In one aspect, screw 50 may be made from coiled 1-inch square 304 stainless bar.
  • [0065]
    FIG. 2B is a side elevation view of alternate screw conveyor 18B which may be used in vessel 12 in place of conveyor 18A. Conveyor 18A may have all the attributes of conveyor 18A discussed above, for example, having screw 50 driven by shaft 52 and plate 54. However, according to one aspect of the invention, conveyor 18B may include a screw conveyor 60 having a central shaft 62 and a plurality of screw flights 64. Conveyor 60 may also be driven by shaft 52, for example, conveyor 60 may be mounted and rotated with plate 54. According to this aspect of the invention, conveyor 60 may promote the movement of material 28 from first end 14 of vessel 12 (see FIG. 1) to minimize or prevent the buildup of material 28 as material 28 is introduced to vessel 12. Conveyor 60 may be sufficiently long to prevent the build up of material 28. In one aspect, conveyor 60 may only extend partially along vessel 12, for example, only from about 1 to 15% of the length of vessel 12. For example, conveyor 60 may be from about 2 feet long to about 10 feet long, depending upon the size of vessel 12 and the length of vessel 12 affected by the introduction of material 28. The diameter of flights 64 may vary and may be large enough to provide a nominal clearance between the inside diameter of screw 50 and outside diameter of flights 64.
  • [0066]
    FIG. 2C is a side elevation view of alternate screw conveyor 18C that may be used in vessel 12 in place of conveyor 18A or 18B. Conveyor 18C may have all the attributes of conveyor 18A discussed above, for example, having screw 50 driven by shaft 52 and plate 54. However, according to one aspect of the invention, conveyor 18C may include a screw conveyor 160 having a plurality of screw flights 164. Conveyor 160 may also be driven by shaft 52, for example, conveyor 160 may be mounted and rotated with plate 54. According to this aspect of the invention, conveyor 160 may promote the movement of material 28 from first end 14 of vessel 12 (see FIG. 1) to minimize or prevent the buildup of material 28 as material 28 is introduced to vessel 12. Conveyor 160 may be sufficiently long to prevent the build up of material 28. In one aspect, conveyor 160 may only extend partially along vessel 12, for example, only from about 1 to 15% of the length of vessel 12. For example, conveyor 160 may be from about 2 feet long to about 10 feet long, depending upon the size of vessel 12 and the length of vessel 12 affected by the introduction of material 28. The diameter of flights 149 may vary and may be large enough to provide a nominal clearance between the inside diameter of screw 50 and outside diameter of flights 149.
  • [0067]
    FIG. 3 is a schematic illustration of another system 210 according to an aspect of the invention in which as least two parallel processing lines each having a system 10 described above and generating gases, for example, syngas and/or gaseous hydrocarbons, which may be recirculated as a source of fuel for the heating devices 36 in the pyrolysis vessels 12.
  • [0068]
    FIG. 4 is front elevation view of a treatment system 110, similar to system 10, according to another aspect of the invention. FIG. 5 is a left side elevation view of the treatment system 110 shown in FIG. 5. FIG. 6 is right side elevation view of the treatment system 110 shown in FIG. 5. This aspect of the invention has many features in common with apparatus 10 shown in FIG. 1. System 110 includes a feed hopper 124; two isolation flapper valves 134, for example, Plattco flapper valves; a conveyor screw 118; a treatment vessel 112, one or more gas discharges 138; and a solid material discharge 150; and solid material discharge conveyor 151. Screw 118 may be a center-less screw similar to screw conveyor 18A, 18B, or 18C shown in FIGS. 2A, 2B, 2C, and 2D. Discharge system conveyor 150 may typically include be a conveyor screw, for example, a center-less conveyor screw similar to conveyor 18A, 18B, or 18C, and, though shown generally directed perpendicular to the axis of vessel 12, conveyor 150 may be oriented at any desired orientation. In one aspect, conveyor 150 may be inclined upward slightly.
  • [0069]
    FIG. 7 is a schematic cross-sectional view of a condensing device or condenser 70 according to one aspect of the invention. Condensing device 70 is adapted to receive one or more gaseous streams, for example, gaseous, hydrocarbon streams, from treatment vessel 12, 112, and condense at least some of the gaseous steams to provide a liquid hydrocarbon, for example, a fuel oil. As show in FIG. 7, condenser 70 includes a vessel 71, at least one inlet 72 for a gaseous stream, at least one outlet 74 for a gaseous stream, and one more outlets 76 for liquid streams. Vessel 71 may be circular or rectangular vessel. According to aspects of the invention, vessel 71 includes at least one, but typically, a plurality of baffles, barriers, or liquid collection trays 78 upon which liquid can collect, as indicated by liquid levels 80 in FIG. 7. In order to promote condensation, barriers or trays 78 may be cooled, for example, by means of an integral heat exchanger, for example, heat exchanges provided with coolant introduced and removed as indicated by double arrows 84. As shown, baffles or barrier 78 may be elevated at one end to promote collection of liquid at the opposite end near outlets 76. According to this aspect of the invention, a gaseous stream 73 introduced to inlet 72 passes upward through or around the series of baffles, as indicated by arrows 86, and is exposed to cooler and cooler surfaces of baffles 80. The liquid condensed from gaseous stream 73 collects on the bottom of vessel 71 or on one or more baffles or barriers 78 and is removed via outlets 76. According to one aspect, one or more, but typically a plurality of liquid streams, may be produced having varying properties, for example, varying hydrocarbon contents or varying BTU content, as indicted in Table 2.
  • EXAMPLE OF ONE ASPECT OF THE INVENTION
  • [0070]
    An example of processing of used tires in accordance with one aspect of the present invention is as follows: Used tires which have been shredded to 2 inch chunks were fed at the rate of 20 pounds per minute into a inlet of an elongated cylindrical pryolysis chamber (such as chamber 12 or 112) which is 32 feet long and 16 inches in internal diameter. The pyrolysis chamber has an electrical motor driven, rotatable helical center-less coil within it having 47 flights which have been sized so as to provide a one-inch clearance between the flights and the interior walls of the pyrolysis chamber. The coil screw conveyor continuously conveys the feed material through the pyrolysis chamber while simultaneously removing build-up of feed material or the pyrolysis products thereof from the inner walls of the pyrolysis chamber. The pyrolysis chamber is heated by a gas-fired heat exchanger and the temperature in the pyrolyzer is maintained at about 450 C. The coil is rotated at 1 RPM and provides for a residence time of 30 to 45 minutes for the material in the pyrolyzer. This temperature and residence time is sufficiently high to pryolyze the feed material to liquid and gaseous hydrocarbons, yet sufficiently low to avoid unduly converting carbon compounds to elemental carbon. The pyrolyzed material is principally made up of liquid and/or gaseous hydrocarbons, steel, carbon, and sulfur. The gaseous pyrolysis products are separated into component streams by cooling and other standard separation techniques. Approximately 504 lbs/hour of liquid hydrocarbon, 125 lb/hour of gaseous hydrocarbon were produced. The liquid-to-gas ratio of the hydrocarbon portion was about 4:1. The liquid hydrocarbon stream was further processed by distillation into gasoline, diesel, heating oil and other “cuts.” The gaseous hydrocarbon stream has a BTU value comparable to natural gas and was recycled back to the pyrolyzer as fuel for the pyrolozer gas fired heater. The steel and carbon were cooled and collected as a mixture of solids (about 570 lbs/hour were produced). The steel was separated from the mixture by use of a magnetic separator.
  • [0071]
    While several aspects of the present invention have been described and depicted herein, alternative aspects may be effected by those skilled in the art to accomplish the same objectives. Accordingly, it is intended by the appended claims to cover all such alternative aspects as fall within the true spirit and scope of the invention.
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Classifications
U.S. Classification201/4, 202/118, 202/117
International ClassificationC10J1/213, C10B7/00, C10B51/00, C10B7/10
Cooperative ClassificationY02P20/143, B01D5/009, B01D5/0057, C10B53/07, C10G1/10, B01D5/0006, C10B7/10, C10B47/44
European ClassificationC10G1/10, C10B53/07, C10B47/44, C10B7/10, B01D5/00H, B01D5/00K16, B01D5/00B10